WorldWideScience

Sample records for arid climate conditions

  1. Effects of climate on the productivity of desert truffles beneath hyper-arid conditions.

    Science.gov (United States)

    Bradai, Lyès; Bissati, Samia; Chenchouni, Haroun; Amrani, Khaled

    2015-07-01

    Desert truffles are edible hypogenous fungi that are very well adapted to conditions of aridity in arid and semi-arid regions. This study aims to highlight the influence of climatic factors on the productivity of desert truffles under hyper-arid climatic conditions of the Sahara Desert in Algeria, with assumptions that the more varying climatic factors, mainly rainfall, are more crucial for the development and production of desert truffles. At seven separate sites, desert truffles were collected by systematic sampling between 2006 and 2012. The effects of climate parameters of each site on the productivities (g/ha/year) of desert truffle species were tested using generalized linear models (GLMs). The annual mean of the total production recorded for all three harvested species (Terfezia arenaria, Terfezia claveryi, and Tirmania nivea) was 785.43 ± 743.39 g/ha. Tirmania nivea was commonly present over the sampled sites with an occurrence of 70 ± 10.1%. GLMs revealed that total and specific productivities were closely positively related to autumnal precipitations occurring during October-December, which is the critical pre-breeding period for both desert truffles and host plant species. The other climatic parameters have statistically no effect on the annual variation of desert truffle productivity. PMID:25164975

  2. Climate phase drives canopy condition in a large semi-arid floodplain forest.

    Science.gov (United States)

    Wen, Li; Saintilan, Neil

    2015-08-15

    To maintain and restore the ecological integrity of floodplains, allocating water for environmental benefits (i.e. environmental water) is widely practised globally. To efficiently manage the always limited environmental water, there is pressing need to advance our understanding of the ecological response to long-term climate cycles as evidence grows of intensification of extreme climatic events such as severe drought and heat waves. In this study, we assessed the alleviating effects of artificial flooding on drought impact using the canopy condition of the iconic river red gum forests in Australia's Murray Darling Basin (MDB). To achieve this, we jointly analysed spatial-temporal patterns of NDVI response and drought conditions for the period of 2000-2013, during which the MDB experienced an extreme dry-wet cycle. Our results indicated that while NDVI-derived canopy condition was better at the sites receiving environmental water during the dry phases, both watered and unwatered sites displayed great similarity in seasonality and trends. Furthermore, we did not find any significant difference in NDVI response of the canopy between the sites to suggest significant differences in ecosystem stability and resilience, with watered and unwatered sites showing similar responses to the extreme wet conditions as the drought broke. The highly significant relationship between long-term drought index and NDVI anomaly suggest that climate phase is the main forcing driving canopy condition in semi-arid floodplain forests. PMID:26027753

  3. Accumulation of pharmaceuticals in groundwater under arid climate conditions - Results from unsaturated column experiments.

    Science.gov (United States)

    Zemann, M; Majewsky, M; Wolf, L

    2016-07-01

    Intense reuse of treated wastewater in agriculture is practiced all over the world, especially in arid and water-scarce regions. In doing so, pharmaceutical residues in the water are irrigated to the soil and subsequently can percolate into the local aquifers. Since evaporation rates in these areas are typically high, persistent substances might enrich in the groundwater recharge of closed catchments like the Jordan Valley. Against this background, unsaturated column tests were conducted to investigate the potential for evaporative accumulation of the two pharmaceuticals bezafibrate and carbamazepine under simulated arid climate conditions. Parallel tests were conducted with inhibited microbiological activity where both substances showed an increase in the effluent concentrations proportional to the evaporation loss of the inflow solution. The mean accumulation factors of the pharmaceuticals correspond to the evaporated water loss. The experiments indicate the accumulation potential for pharmaceuticals with high persistence against biodegradation. For the first time, the overall potential for evaporative enrichment could be demonstrated for pharmaceuticals. Under the given experimental conditions, the two investigated pharmaceuticals did not enrich faster than chloride, which might result in soil salting prior to reaching harmful pharmaceutical concentrations in soil water. The findings are relevant to future assessments of environmental impacts of persistent trace substances, which need to take into account that concentrations in the aquatic cycle might increase further due to evaporative enrichment. PMID:27085060

  4. Can environmental conditions affect smallholders' climate change perception? Evidence from an aridity gradient in the Gobi desert.

    Science.gov (United States)

    Rueff, Henri

    2016-04-01

    There is a growing interest in smallholders' climate change perception (CCP). Understanding what people perceive in relation to the climate they endure supports national climate change adaptation policy especially relevant to uncertain and resource-scarce environments. Most research so far focused on the accuracy of CCP compared to observed climatic data. However, the potential effect of factors influencing peoples' perceptions remains largely unstudied. This research tests two hypotheses in a desert environment; first, that CCP varies along an aridity gradient, and, second, that respondents are more consistent (answers less far apart) in their CCP when facing more climate shocks, which supports the first hypothesis. A semi-structured survey was conducted among nomadic (Mongolia) (n=180) and semi-nomadic (Inner Mongolia-China) (n=180) herders, to analyse perception along an aridity gradient (proxied by Normalised Difference Vegetation Index) covering an array of climate change issues in the Gobi. Results suggests that environmental conditions have a significant effect on CCP but only in terms of experienced climate shocks. The CCP for other climatic variables (rain, season length) is more diffused and can poorly be predicted by the surrounding environment smallholders live in. Institutional contrasts between China and Mongolia explain marginally differences of perception. Further research is needed to validate these results among smallholders on other environmental gradient types, for examples along altitudinal biome stratification in mountain environments.

  5. CHARACTERISTICS OF ARIDITY CONDITIONS IN SOUTH DOBRUDJA

    OpenAIRE

    A. TISCOVSCHI; GABRIELA MANEA; O. COCOS; IULIANA VIJULIE; ROXANA CUCULICI

    2013-01-01

    Characteristics of Aridity Conditions in South Dobrudja. For most people, the arid and semi-arid lands are those where precipitation is low (less than 200 mm per year), and yet enough for supplying streams capable of temporarily carrying the debris resulted from weathering, but insufficient for encouraging the development of a vegetal cover meant to protect the soil blanket against eroding agents. The drought is a major and permanent climatic risk for the Dobrudja territory as a whole and for...

  6. What Climate Conditions Enhance Hillslope Erosion in Semi-Arid Regions?

    Science.gov (United States)

    Pierce, J. L.; Riley, K. E.; Kenworthy, M.; Poulos, M. J.; Weppner, K.; Nelson, N.; Svenson, L.

    2011-12-01

    Researchers have long pondered the question of how climate and climate change influence rates and processes of erosion: this question has become more relevant in the face of ongoing and future anthropogenic warming. We examine evidence of hillslope erosion and sedimentation on alluvial fans over Holocene and Quaternary timescales throughout a range of ecosystems in Idaho, USA. Records of erosion include fire-related and non-fire related deposition on alluvial fans, and landscape-scale analysis of hillslope slope angles. Over Holocene timescales, five independent records of forest-fires and fire-related erosion from sagebrush steppe, pinion-juniper, ponderosa pine, lodgepole pine and mixed conifer ecosystems indicate that sedimentation rates and processes on alluvial fans vary temporally with Holocene climate and spatially with vegetation type. Despite variations in ecosystem type and associated fire regimes, all sites show similar broad-scale temporal patterns. The mid-Holocene (~4-8 ka) is characterized by few fire-related deposits and many non-fire related sheetflooding events (vs. debris flows); this relatively fire-free interval is punctuated by fire peaks and associated sheetflooding ~7-6 ka. As regional paleoclimatic reconstructions generally indicate this time was generally warm and dry the lack of fire is somewhat counterintuitive; however, decreased fuel loads, combined with perhaps a more stable climate may reduce fire and storm intensity and frequency. Late Holocene (last ~3 ka) cooler, wetter and more variable climates (as compared to the mid-Holocene) are characterized by increased fire activity at all sites, and more large debris flows. Medieval droughts correspond with major fire and debris flow peaks ~1000-800 cal yr BP; decadal to annual droughts during the generally cooler and wetter LIA also promote fire peaks ~500-300 cal yr BP. Modern observations of hillslope erosion indicate north-facing or moister slopes are characterized by dense vegetation

  7. Aridity under conditions of increased CO2

    Science.gov (United States)

    Greve, Peter; Roderick, Micheal L.; Seneviratne, Sonia I.

    2016-04-01

    A string of recent of studies led to the wide-held assumption that aridity will increase under conditions of increasing atmospheric CO2 concentrations and associated global warming. Such results generally build upon analyses of changes in the 'aridity index' (the ratio of potential evaporation to precipitation) and can be described as a direct thermodynamic effect on atmospheric water demand due to increasing temperatures. However, there is widespread evidence that contradicts the 'warmer is more arid' interpretation, leading to the 'global aridity paradox' (Roderick et al. 2015, WRR). Here we provide a comprehensive assessment of modeled changes in a broad set of dryness metrics (primarily based on a range of measures of water availability) over a large range of realistic atmospheric CO2 concentrations. We use an ensemble of simulations from of state-of-the-art climate models to analyse both equilibrium climate experiments and transient historical simulations and future projections. Our results show that dryness is, under conditions of increasing atmospheric CO2 concentrations and related global warming, generally decreasing at global scales. At regional scales we do, however, identify areas that undergo changes towards drier conditions, located primarily in subtropical climate regions and the Amazon Basin. Nonetheless, the majority of regions, especially in tropical and mid- to northern high latitudes areas, display wetting conditions in a warming world. Our results contradict previous findings and highlight the need to comprehensively assess all aspects of changes in hydroclimatological conditions at the land surface. Roderick, M. L., P. Greve, and G. D. Farquhar (2015), On the assessment of aridity with changes in atmospheric CO2, Water Resour. Res., 51, 5450-5463

  8. Modeling the effects of climate on date palm scale ( Parlatoria blanchardi) population dynamics during different phenological stages of life history under hot arid conditions

    Science.gov (United States)

    Idder-Ighili, Hakima; Idder, Mohamed Azzedine; Doumandji-Mitiche, Bahia; Chenchouni, Haroun

    2015-10-01

    The date palm scale (DPS) Parlatoria blanchardi is a serious pest due to the damage it inflicts on its host tree ( Phoenix dactylifera). To develop an effective control against DPS in arid regions, it is essential to know its bio-ecology including population dynamics and climatic factors influencing the duration and timing of life history and also the densities of different phenological stages (crawlers, first and second instars nymphs, adult males, and adult females). Monitoring of biological cycle and population dynamics of the pest were achieved through weekly counts of DPS densities on leaflets sampled at different position of date palm trees in an oasis of Ouargla region (Algerian Sahara Desert). Within this hyper-arid region, DPS established four generations per year, the most important was the spring generation. Two overlapping generations occurred in spring-early summer and two in autumn-early winter; these two pairs of generations were interspersed by two phases of high-mortality rates, the first corresponds to winter cold and the second refers to the extreme heat of summer. Statistical analysis of the effects of the studied climatic conditions (minimum, maximum and mean temperatures, precipitation, humidity, wind, rain days, and climatic indices) on the DPS densities at different phenological stages showed great variability from one stage to another. Among these, adult females were the most affected by climate factors. For the total DPS population, high values of minimum temperatures negatively affected population density, while high maximum temperatures, hygrometry, and De Martonne aridity index showed a positive influence.

  9. Effects of climate change on agriculture particularly in semi-arid tropics of the world with some examples of Ethiopian condition

    International Nuclear Information System (INIS)

    Today climate change is a burning issue all over the world because of its global nature. Fears have arisen that, climate may be changing for the worse and its impact may be felt on agricultural production, which will reduce the supply of food to growing population, especially in developing countries. Climate change would affect various human activities. Agriculture is one of the activities, which can be seriously affected by climate change. Due to high inter-annual variability and uneven distribution of rainfall during the rainy season, recurrent droughts have been observed in semi-arid tropics of the world over the last three decades. As White (1996) pointed out rain fed agriculture in the semi-arid tropics is limited mostly by high climatic variability with principal limiting factor being rainfall. The main crops of traditional rain fed agriculture are sorghum, millet, maize, cowpea, pulses and sesame. There is a suggestion that increased CO2 will benefit temperate and humid tropical agriculture more than that in the semi-arid tropics. During the process of photosynthesis plant species with the C3 photosynthetic pathway tend to respond positively to increased CO2 while the C4 have a poor response. Since C4 plants are mostly tropical crops, the situation will be worst over the areas (Parry, 1990). Climate change will alter the nature of occurrence of agricultural pests in terms of area. Warmer temperatures shorten the generation time; increase the development rate of epidemic. For example, assessment of the effect of global warming on the distribution of livestock disease suggests that pests at present limited to tropical countries may spread into other parts of the world, which have different climatic condition (ibid).(Author)

  10. CHARACTERISTICS OF ARIDITY CONDITIONS IN SOUTH DOBRUDJA

    Directory of Open Access Journals (Sweden)

    A. TISCOVSCHI

    2013-04-01

    Full Text Available Characteristics of Aridity Conditions in South Dobrudja. For most people, the arid and semi-arid lands are those where precipitation is low (less than 200 mm per year, and yet enough for supplying streams capable of temporarily carrying the debris resulted from weathering, but insufficient for encouraging the development of a vegetal cover meant to protect the soil blanket against eroding agents. The drought is a major and permanent climatic risk for the Dobrudja territory as a whole and for South Dobrudja in particular, a territory where hydrographic network is underdeveloped, streams are ephemeral, and semi-endorheic areas are well developed. When the period of moisture deficiency lasts longer, it can bring about a significant water imbalance, which results in crop losses or restrictions in water consumption, thus leading to a number of economic problems. Under the circumstances, the risk of aridity expansion is significant, this being the reason why a better water management system in Romania is urgently needed. In the last decades, the numerous specialty studies undertaken in the area have emphasized an intensification of the process of dryness, because atmospheric and pedological droughts have become more and more serious. Romania is a member of the United Nations Convention to Combat Desertification (UNCCD and the World Meteorological Organization (WMO. It actively participates within the drought management network and the Drought Management Center for Southeastern Europe, which comprises 11 countries. The scope is to work together and exchange experience with the neighboring countries that have recorded positive results and acquired a rich experience in terms of drought management. The employment of appropriate pluvial indices in identifying the areas prone to aridity may prove to be convenient tool for finding practical solutions meant to mitigate the impact of this phenomenon on the local communities living in South Dobrudja.

  11. Shallow Horizontal GCHP Effectiveness in Arid Climate Soils

    Science.gov (United States)

    North, Timothy James

    Ground coupled heat pumps (GCHPs) have been used successfully in many environments to improve the heating and cooling efficiency of both small and large scale buildings. In arid climate regions, such as the Phoenix, Arizona metropolitan area, where the air condi-tioning load is dominated by cooling in the summer, GCHPs are difficult to install and operate. This is because the nature of soils in arid climate regions, in that they are both dry and hot, renders them particularly ineffective at dissipating heat. The first part of this thesis addresses applying the SVHeat finite element modeling soft-ware to create a model of a GCHP system. Using real-world data from a prototype solar-water heating system coupled with a ground-source heat exchanger installed in Menlo Park, California, a relatively accurate model was created to represent a novel GCHP panel system installed in a shallow vertical trench. A sensitivity analysis was performed to evaluate the accuracy of the calibrated model. The second part of the thesis involved adapting the calibrated model to represent an ap-proximation of soil conditions in arid climate regions, using a range of thermal properties for dry soils. The effectiveness of the GCHP in the arid climate region model was then evaluated by comparing the thermal flux from the panel into the subsurface profile to that of the prototype GCHP. It was shown that soils in arid climate regions are particularly inefficient at heat dissipation, but that it is highly dependent on the thermal conductivity inputted into the model. This demonstrates the importance of proper site characterization in arid climate regions. Finally, several soil improvement methods were researched to evaluate their potential for use in improving the effectiveness of shallow horizontal GCHP systems in arid climate regions.

  12. Preliminary assessment of aridity conditions in the Iberian Peninsula

    Science.gov (United States)

    Andrade, C.; Corte-Real, J. A.

    2016-06-01

    Aridity is one of the key elements characterizing the climate of a region, having a severe impact on human activities. Aiming at assessing aridity conditions in the Iberian Peninsula, the spatial distribution of the UNEP aridity index is analyzed during the period 1901-2012. Gridded precipitation and potential evapotranspiration datasets are used on a monthly basis. Results show that the southern half of Iberia is particularly vulnerable to water stress and hence to desertification processes. In particular, the UNEP aridity index reveals an increase and northward extension of the semi-arid regime in the Iberian Peninsula between 1901 and 2012. More than 50% of the north and western territory have experienced humid/sub-humid conditions, while the other regions underwent semi-arid settings. Results also reveal that climate was subjected to spatial and temporal variabilities with an overall statistically significant (at a 95% confidence level) trend to aridification in the south-easternmost and central regions. The remaining territory of the Iberian Peninsula does not reveal statistically significant trends.

  13. Climate Warming Threatens Semi-arid Forests in Inner Asia

    Science.gov (United States)

    WU, X.; Liu, H.; Qi, Z.; Li, X.

    2014-12-01

    A line of evidences reveal an increasing tree growth decline and tree mortality mainly attributable to climate warming and the warming-mediated changes in drought and other processes (such as fire and insect dynamics) in many parts of world tropical, temperate and boreal forests. However, the growth responses to climate change of the widely distributed semi-arid forests are unclear. Here, we synthetically investigate the tree growth patterns during past decades and its interannual response to climate variations in Inner Asia combining the ground truth field survey and samplings, remote sensing observations and climate data. We identified a pervasive tree growth decline since mid-1990s in semi-arid forests in Inner Asia. The widely observed tree growth decline is dominantly attributable to warming-induced water stress during pre- and early growing season. Tree growth of semi-arid forests in Inner Asia is particularly susceptible to spring warming and has been suffering a prolonged growth limitation in recent decades due to spring warming-mediated water conditions. Additionally, we identified a much slower growth rate in younger trees and a lack of tree regeneration in these semi-arid forests. The widely observed forest growth reduction and lack of tree regeneration over semi-arid forests in Inner Asia could predictably exert great effects on forest structure, regionally/globally biophysical and biochemical processes and the feedbacks between biosphere and atmosphere. Notably, further increases in forest stress and tree mortality could be reasonably expected, especially in context of the increase frequency and severity of high temperature and heat waves and changes in forest disturbances, potentially driving the eventual regional loss of current semi-arid forests. Given the potential risks of climate induced forest dieback, increased management attention to adaptation options for enhancing forest resistance and resilience to projected climate stress can be expected

  14. Effect of Harvest of Air Relative Humidity on Water and Heat Transfer in Soil With Crops Under Arid Climatic Conditions

    Directory of Open Access Journals (Sweden)

    El Khadir LAKHAL

    2015-05-01

    Full Text Available In this work, the main objective is to analyze the effect of the harvest of air relative humidity on soil temperature, soil water storage and evaporation. An experiment work was conducted in order to evaluate the quantity of soil water adsorbed by harvesting of relative air humidity. This experimental work was conducted on hilly areas with various hypsographic and microclimatic conditions greatly affecting daily fluctuations of air humidity and soil characteristics. The metrological data needed by SISPAT model were obtained by using a Campbell Scientific equipments Station recorder on data loggers every half hour. A numerical model based on SiSPAT (Système d’Interaction Sol Plante Atmosphère formulation is adopted. The general equations of the proposed model are based on heat and mass transfer in the soil, atmosphere and plant system. This study shows that Soil Water Adsorption (SWA induce an increasing in the total evaporation and in soil water storage especially on the upper layers. The effect of Soil Water Adsorption on soil temperature appears for the first layers of soil and become absent in the profound zone because the vapour condensation phenomenon is very important at night for the first layers.

  15. Dust aerosol effect on semi-arid climate over Northwest China detected from A-Train satellite measurements

    OpenAIRE

    Huang, J; Minnis, P.; Yan, H; Yi, Y.; Chen, B; Zhang, L.; J. K. Ayers

    2010-01-01

    The impact of dust aerosols on the semi-arid climate of Northwest China is analyzed by comparing aerosol and cloud properties derived over the China semi-arid region (hereafter, CSR) and the United States semi-arid region (hereafter, USR) using several years of surface and A-Train satellite observations during active dust event seasons. These regions have similar climatic conditions, but aerosol concentrations are greater over the CSR. Because the CSR is close to two major dust source regions...

  16. Climatic growing conditions of Jatropha curcas L.

    Energy Technology Data Exchange (ETDEWEB)

    Maes, W.H.; Achten, W.M.J.; Muys, B. [Katholieke Universiteit Leuven, Division Forest, Nature and Landscape, Celestijnenlaan 200 E Box 2411, BE-3001 Leuven (Belgium); Trabucco, A. [Katholieke Universiteit Leuven, Division Forest, Nature and Landscape, Celestijnenlaan 200 E Box 2411, BE-3001 Leuven (Belgium); International Water Management Institute (IWMI), P.O. Box 2075, Colombo (Sri Lanka)

    2009-10-15

    The massive investment in new jatropha plantations worldwide is not sufficiently based on a profound scientific knowledge of its ecology. In this article, we define the climatic conditions in its area of natural distribution by combining the locations of herbarium specimens with corresponding climatic information, and compare these conditions with those in 83 jatropha plantations worldwide. Most specimens (87%) were found in tropical savannah and monsoon climates (A{sub m}, A{sub w}) and in temperate climates without dry season and with hot summer (C{sub fa}), while very few were found in semi-arid (B{sub S}) and none in arid climates (B{sub W}). Ninety-five percent of the specimens grew in areas with a mean annual rainfall above 944 mm year{sup -1} and an average minimum temperature of the coldest month (T{sub min}) above 10.5 C. The mean annual temperature range was 19.3-27.2 C. The climatic conditions at the plantations were different from those of the natural distribution specimens for all studied climatic variables, except average maximum temperature in the warmest month. Roughly 40% of the plantations were situated in regions with a drier climate than in 95% of the area of the herbarium specimens, and 28% of the plantations were situated in areas with T{sub min} below 10.5 C. The observed precipitation preferences indicate that jatropha is not common in regions with arid and semi-arid climates. Plantations in arid and semi-arid areas hold the risk of low productivity or irrigation requirement. Plantations in regions with frost risk hold the risk of damage due to frost. (author)

  17. Aridity changes in the Tibetan Plateau in a warming climate

    Science.gov (United States)

    Gao, Yanhong; Li, Xia; Leung, L. Ruby; Chen, Deliang; Xu, Jianwei

    2015-03-01

    Desertification in the Tibetan Plateau (TP) has drawn increasing attention in the recent decades. It has been postulated as a consequence of increasing climate aridity due to the observed warming. This study quantifies the aridity changes in the TP and attributes the changes to different climatic factors. Using the ratio of precipitation to potential evapotranspiration (P/PET) as an aridity index, we used observed meteorological records at 83 stations in the TP to calculate PET using the Penman-Monteith algorithm and the ratio. Spatial and temporal changes of P/PET in 1979-2011 were analyzed. Results show that stations located in the arid and semi-arid northwestern TP are becoming significantly wetter, and half of the stations in the semi-humid eastern TP are becoming drier, though not significantly, in the recent three decades. The aridity change patterns are significantly correlated with the change patterns of precipitation, sunshine duration and diurnal temperature range. Temporal correlations between the annual P/PET ratio and other meteorological variables confirm the significant correlation between aridity and the three variables, with precipitation being the dominant driver of P/PET changes at the interannual time scale. Annual PET are insignificantly but negatively correlated with P/PET in the cold season. In the warm season, however, the correlation between PET and P/PET is significant at the confidence level of 99.9% when the cryosphere near the surface melts. Significant correlation between annual wind speed and aridity occurs in limited locations and months. Consistency in the climatology pattern and linear trends in surface air temperature and precipitation calculated using station data, gridded data, and nearest grid-to-stations for the TP average and across sub-basins indicate the robustness of the trends despite the large spatial heterogeneity in the TP that challenge climate monitoring.

  18. Aridity changes in the Tibetan Plateau in a warming climate

    International Nuclear Information System (INIS)

    Desertification in the Tibetan Plateau (TP) has drawn increasing attention in the recent decades. It has been postulated as a consequence of increasing climate aridity due to the observed warming. This study quantifies the aridity changes in the TP and attributes the changes to different climatic factors. Using the ratio of precipitation to potential evapotranspiration (P/PET) as an aridity index, we used observed meteorological records at 83 stations in the TP to calculate PET using the Penman–Monteith algorithm and the ratio. Spatial and temporal changes of P/PET in 1979–2011 were analyzed. Results show that stations located in the arid and semi-arid northwestern TP are becoming significantly wetter, and half of the stations in the semi-humid eastern TP are becoming drier, though not significantly, in the recent three decades. The aridity change patterns are significantly correlated with the change patterns of precipitation, sunshine duration and diurnal temperature range. Temporal correlations between the annual P/PET ratio and other meteorological variables confirm the significant correlation between aridity and the three variables, with precipitation being the dominant driver of P/PET changes at the interannual time scale. Annual PET are insignificantly but negatively correlated with P/PET in the cold season. In the warm season, however, the correlation between PET and P/PET is significant at the confidence level of 99.9% when the cryosphere near the surface melts. Significant correlation between annual wind speed and aridity occurs in limited locations and months. Consistency in the climatology pattern and linear trends in surface air temperature and precipitation calculated using station data, gridded data, and nearest grid-to-stations for the TP average and across sub-basins indicate the robustness of the trends despite the large spatial heterogeneity in the TP that challenge climate monitoring. (letter)

  19. Extreme climatic events shape arid and semiarid ecosystems

    NARCIS (Netherlands)

    Holmgren, M.; Stapp, P.; Dickman, C.; Gracia, C.; Graham, S.

    2006-01-01

    Climatic changes associated with the El Nino Southern Oscillation (ENSO) can have a dramatic impact on terrestrial ecosystems worldwide, but especially on arid and semiarid systems, where productivity is strongly limited by precipitation. Nearly two decades of research, including both short-term exp

  20. Investigation of agricultural residues gasification for electricity production in Sudan as an example for biomass energy utilization under arid climate conditions in developing countries

    Energy Technology Data Exchange (ETDEWEB)

    Bakhiet, Arig G.

    2008-05-15

    This study examines the possibility of electricity production through gasification of agricultural residues in Sudan. The study begins in Chapter 1, by providing general contextual analysis of the energy situation (production and consumption patterns) in Sudan with specific focus on electricity. It proceeded to study the potential of Petroleum, Biomass and other renewable sources for electricity production. Dramatic increase in electricity production was found to be essential especially through decentralised power plants as the current electricity production services cover {proportional_to} 13 % of the population of Sudan. Biomass potential in Sudan justifies the use of agricultural residues as energy source; its potential was estimated by {proportional_to} 350000 TJ/a. Further, the urban centres of arid regions in western Sudan were identified as the target group for this study. In chapter 2, specific investigations for selected study area through field work using statistical tools such as questionnaires, interviews and field observation show that income is highly correlated to electricity consumption. The flat rate system did not result in higher consumption thus the assumption that this consumption will not drastically change in the next 10 years could be accepted. As orientation value for BGPP, 8000 tons of GN.S are available annually, the average electricity consumption is {proportional_to} 4 kWh/day/family while acceptable price could be 40 SDD/kWh (0.15 Euro). In chapter 3, literature review was carried to spot out the comparative merits of the gasification technology and the most optimum gasifying and electricity production system. As a result downdraft gasifier and ICE were suggested as suitable systems. In chapter 4, fuel properties and fuel properties of agricultural residues were studied, different samples were tested and the results were presented. The main conclusions derived were: fuel properties of agricultural residues are modifiable properties, so

  1. Climate risk management for water in semi–arid regions

    OpenAIRE

    Robertson, Andrew W.; Baethgen, Walter; Block, Paul; Lall, Upmanu; Sankarasubramanian, Arumugam; de Assis de Souza Filho, Francisco; Verbist, Koen

    2014-01-01

    Background: New sources of hydroclimate information based on forecast models and observational data have the potential to greatly improve the management of water resources in semi-arid regions prone to drought. Better management of climate-related risks and opportunities requires both new methods to develop forecasts of drought indicators and river flow, as well as better strategies to incorporate these forecasts into drought, river or reservoir management systems. In each case the existing i...

  2. Landscaping and performance of some aesthetic plant species in hot,arid conditions of India

    Institute of Scientific and Technical Information of China (English)

    Rajesh Kumar Gupta; Pradeep Chaudhry; Rameshwar Lal Srivastava

    2012-01-01

    Abstract:Establishment of ornamental and aesthetic plants in hot,arid conditions of India is difficult due to the prevailing climatic,edaphic and biotic factors.Effect of turfgrass on the growth of ornamental plants in hot arid conditions has not been studied so far anywhere in the world.A study was conducted on the campus of Arid Forest Research Institute,Jodhpur,India to assess the performance of a few ornamental plant species in combination with turfgrass and without turfgrass with respect to different soil tilling intervals.Growth of plants was better with turfgrass than without turfgrass.We suggest adopting a soil tilling interval of 30 days to achieve optimum growth of ornamental plant species in terms of height and crown diameter.Our results can help reduce labor costs and achieving better landscapes in fewer days in hot urban conditions of Indian sub continent.

  3. Regional difference of aridity/humidity conditions changeover China during the last thirty years

    Institute of Scientific and Technical Information of China (English)

    YIN Yunhe; WU Shaohong; ZHENG Du; YANG Qingye

    2005-01-01

    The meteorological data of 616 stations in China were used to calculate the potential evapotranspiration and aridity/humidity index by applying the modified FAO-Penman-Monteith model. Regional difference of trends in precipitation, potential evapotranspiration and aridity/humidity index over China and their interdecadal variations were analyzed from 1971 to 2000. The results show that all the four climatic factors trends have obvious regional difference and interdecadal variations. Annual precipitation during the 30-year period shows an increasing trend over most regions of China, with decreasing trends in potential evapotranspiration and aridity/humidity index. Most regions in China become more humid, especially significant in northern Xinjiang, eastern Tibet, western Sichuan, and northern Yunnan. The average value over China would mask the regional difference of climate change because of the complex environmental condition in China. Therefore regional difference should be analyzed to further understand climate change and its impacts. Both water supply and demand need to be considered when attempting to study regional aridity/humidity conditions.

  4. Mitigating Climate Change in the Arid Lands of Namibia

    Science.gov (United States)

    Schneider, Martin B.; Sorensen, Marten

    2014-05-01

    Mitigating Climate Change in the Arid Lands of Namibia Namibia is the most arid country south of the Sahara, with scarce rainfall and perennial rivers only at its borders, > 80% of the area relies solely on groundwater. This has had devastating economic effects limiting opportunities for sustainable rural livelihoods that keep the population majority living below the World Bank poverty line (IFAD, 2013). A primary example of climatic variability which affects agrarian productivity is increased bush encroachment of Namibia's arid grazing land. The result has been a severe biodiversity loss, increased desertification and diminished water-use efficiency and underground water tables. Given these factors, Namibia's arid lands provide a unique opportunity to assess and test innovative / appropriate adaptation and mitigation strategies. Working toward sustainable management, restoration, and maintenance of balanced, resilient arid ecosystems in Namibia will also be a means to support and expand economic sectors incl. opportunities for job creation and potentially provide a model for similar arid regions. Main vegetation zones are: desert (46%), savannah (37%), and dry woodlands and forests (17%), i.e. dimensions of management strategies within stakeholder groups using participatory approaches. 3. Determine science-based alternatives for adaptive land management strategies and test their acceptability to local communities and within the current policy framework. 4. Integrate identified indigenous knowledge with appropriate science and new emerging technologies to develop a training toolkit of effective strategies relevant to all stakeholders. 5. Utilize training sessions, education workshops, curriculum revisions, and appropriate information and communication technologies (ICTs) including social media outlets to disseminate the toolkit strategies. 6. Apply a modified logic model approach within a value chain analysis process to evaluate program effectiveness and impacts at

  5. Lighting and Energy Performance of an Adaptive Shading and Daylighting System for Arid Climates

    OpenAIRE

    Giovannini, Luigi; Lo Verso, Valerio Roberto Maria

    2015-01-01

    Finding the proper trade-off between blocking direct sunlight, ensuring sufficient indoor daylighting and view out is a particularly delicate task especially in arid climates, due to harsh environmental conditions. As a tentative answer to this challenge, an adaptive shading and daylighting system (Shape Variable Mashrabiya - SVM) has been developed by the authors, described in an earlier paper. In this paper, we analyze how the SVM may affect annual lighting and global primary energy perform...

  6. New multi-model approach gives good estimations of wheat yield under semi-arid climate in Morocco

    OpenAIRE

    Bregaglio , S.; N. Frasso; V. Pagani; T. Stella; Francone, C.; Cappelli, G.; Acutis, M.; Balaghi, R.; Ouabbou, H.; Paleari, L.; R. Confalonieri

    2015-01-01

    Wheat production in Morocco is crucial for economy and food security. However, wheat production is difficult because the semi-arid climate causes very variable wheat yields. To solve this issue, we need better prediction of the impact of drought on wheat yields to adapt cropping management to the semi-arid climate. Here, we adapted the models WOFOST and CropSyst to agro-climatic conditions in Morocco. Six soft and durum wheat varieties were grown during the 2011–2012 and 2012–2013 growing sea...

  7. Co-inoculation with Rhizobium and plant growth promoting rhizobacteria (PGPR for inducing salinity tolerance in mung bean under field condition of semi arid climate

    Directory of Open Access Journals (Sweden)

    Muhammad Aamir

    2013-04-01

    Full Text Available Salinity stress severely affects the growth, nodulation and yield of mung bean (Vigna radiata L.. However, its growth can be improved under salinity stress by inoculation/co-inoculation with rhizobia and plant growth promoting rhizobacteria (PGPR containing 1-Aminocyclopropane-1-carboxylic acid (ACC deaminase enzyme. ACC-deaminase containing bacteria regulate the stress induced ethylene production by hydrolyzing the ACC (immediate precursor of ethylene into ammonia and ketobutyric acid, thus improve plant growth by lowering the ethylene level. A study was conducted under salt affected field conditions where pre-isolated strains of Rhizobium and PGPR were used alone as well as in combination for mitigating the salinity stress on growth, nodulation and yield of mung bean by following the randomized complete block design (RCBD. The data were recorded and analyzed statistically to see the difference among treatments.

  8. Mitigating Climate Change in the Arid Lands of Namibia

    Science.gov (United States)

    Schneider, Martin B.; Sorensen, Marten

    2014-05-01

    Mitigating Climate Change in the Arid Lands of Namibia Namibia is the most arid country south of the Sahara, with scarce rainfall and perennial rivers only at its borders, > 80% of the area relies solely on groundwater. This has had devastating economic effects limiting opportunities for sustainable rural livelihoods that keep the population majority living below the World Bank poverty line (IFAD, 2013). A primary example of climatic variability which affects agrarian productivity is increased bush encroachment of Namibia's arid grazing land. The result has been a severe biodiversity loss, increased desertification and diminished water-use efficiency and underground water tables. Given these factors, Namibia's arid lands provide a unique opportunity to assess and test innovative / appropriate adaptation and mitigation strategies. Working toward sustainable management, restoration, and maintenance of balanced, resilient arid ecosystems in Namibia will also be a means to support and expand economic sectors incl. opportunities for job creation and potentially provide a model for similar arid regions. Main vegetation zones are: desert (46%), savannah (37%), and dry woodlands and forests (17%), i.e. management strategies currently used by rural communities. 2. Capture and assess cultural and gender dimensions of management strategies within stakeholder groups using participatory approaches. 3. Determine science-based alternatives for adaptive land management strategies and test their acceptability to local communities and within the current policy framework. 4. Integrate identified indigenous knowledge with appropriate science and new emerging technologies to develop a training toolkit of effective strategies relevant to all stakeholders. 5. Utilize training sessions, education workshops, curriculum revisions, and appropriate information and communication technologies (ICTs) including social media outlets to disseminate the toolkit strategies. 6. Apply a modified logic

  9. Arid Climate Landscape Evolution and the Pediment Problem

    Science.gov (United States)

    Strudley, M. W.; Murray, A. B.; Haff, P. K.

    2003-12-01

    Although widely disseminated throughout many different climatic environments, pediments, or gently sloping, laterally extensive surfaces characterized by a thin veneer of alluvium covering bedrock, are particularly well developed in granitic desert locales such as the Mojave and Colorado Deserts in southern California and the Sonoran Desert in western Arizona. These features form a transitional zone within the piedmont of many exposed batholithic mountainous bodies, separating a zone of bare bedrock erosion in the steep mountain mass from a depositional zone in the alluvial basin. Well developed pediments in granitic environments commonly contain bedrock outcroppings (tors or inselbergs) that may remain uncovered indefinitely and sharp slope discontinuities at the piedmont junction separating the pediment surface from the mountain mass. Pediments have been the focus of debate in geomorphic circles for over half a century. While some geomorphologists have proposed that pediments and their associated tor fields represent unearthed relict landforms, others propose unique modes of sediment transport that form and maintain the beveled form of pediment surfaces. We hypothesize that a simple relationship between bedrock weathering and alluvial thickness could explain this range of enigmatic features and phenomena, a relationship that Anderson (2002) incorporates in his proposed explanation for high alpine surfaces and tors. Field observations suggest that the transformation of bedrock to regolith is most rapid with a finite covering of regolith. This weathering rule, combined with a simple set of sediment transport rules provides a mechanism through which pediment surfaces are produced. We examine the development of pediment surfaces and associated features using a 3D numerical, distributed-parameter landscape evolution model incorporating the most pertinent landscape development processes acting in arid regions. Temporally and spatially variable rainfall (storm size

  10. Impacts of climate change on nutrient cycling in semi-arid and arid ecosystems

    Energy Technology Data Exchange (ETDEWEB)

    Belnap, J. [National Biological Survey, Moab, UT (United States)

    1995-09-01

    Effective precipitation is a major factor in determining nutrient pathways in different ecosystems. Soil flora and fauna play a critical role in nutrient cycles of all ecosystems. Temperature, timing, and amounts of precipitation affect population composition, activity levels, biomass, and recovery rates from disturbance. Changes in these variables can result in very different inputs and outputs for different nutrients. As a result, areas with less effective precipitation have very different nutrient cycles than more mesic zones. Climate change, therefore, can profoundly affect the nutrient cycles of ecosystems. Nitrogen cycles may be especially sensitive to changes in temperature and to timing and amounts of precipitation. Rainfall contains varying amounts of nitrogen compounds. Changes in amounts of rainfall will change amounts of nitrogen available to these systems. Because rainfall is limited in semi-arid and regions, these systems tend to be more dependent on microbial populations for nitrogen input. Consequently, understanding the effects of climate change on these organisms is critical in understanding the overall effect on ecosystems.

  11. Wind power variations under humid and arid meteorological conditions

    International Nuclear Information System (INIS)

    Highlights: • It indicates the role of weather parameters’ roles in the wind energy calculation. • Meteorological variables are more significant in arid regions for wind power. • It provides opportunity to take into consideration air density variability. • Wind power is presented in terms of the wind speed, temperature and pressure. - Abstract: The classical wind power per rotor area per time is given as the half product of the air density by third power of the wind velocity. This approach adopts the standard air density as constant (1.23 g/cm3), which ignores the density dependence on air temperature and pressure. Weather conditions are not taken into consideration except the variations in wind velocity. In general, increase in pressure and decrease in temperature cause increase in the wind power generation. The rate of increase in the pressure has less effect on the wind power as compared with the temperature rate. This paper provides the wind power formulation based on three meteorological variables as the wind velocity, air temperature and air pressure. Furthermore, from the meteorology point of view any change in the wind power is expressed as a function of partial changes in these meteorological variables. Additionally, weather conditions in humid and arid regions differ from each other, and it is interesting to see possible differences between the two regions. The application of the methodology is presented for two meteorology stations in Istanbul, Turkey, as representative of the humid regions and Al-Madinah Al-Monawwarah, Kingdom of Saudi Arabia, for arid region, both on daily record bases for 2010. It is found that consideration of air temperature and pressure in the average wind power calculation gives about 1.3% decrease in Istanbul, whereas it is about 13.7% in Al-Madinah Al-Monawwarah. Hence, consideration of meteorological variables in wind power calculations becomes more significant in arid regions

  12. An Evaluation of Unsaturated Flow Models in an Arid Climate

    International Nuclear Information System (INIS)

    The objective of this study was to evaluate the effectiveness of two unsaturated flow models in arid regions. The area selected for the study was the Area 5 Radioactive Waste Management Site (RWMS) at the Nevada Test Site in Nye County, Nevada. The two models selected for this evaluation were HYDRUS-1D [Simunek et al., 1998] and the SHAW model [Flerchinger and Saxton, 1989]. Approximately 5 years of soil-water and atmospheric data collected from an instrumented weighing lysimeter site near the RWMS were used for building the models with actual initial and boundary conditions representative of the site. Physical processes affecting the site and model performance were explored. Model performance was based on a detailed sensitivity analysis and ultimately on storage comparisons. During the process of developing descriptive model input, procedures for converting hydraulic parameters for each model were explored. In addition, the compilation of atmospheric data collected at the site became a useful tool for developing predictive functions for future studies. The final model results were used to evaluate the capacities of the HYDRUS and SHAW models for predicting soil-moisture movement and variable surface phenomena for bare soil conditions in the arid vadose zone. The development of calibrated models along with the atmospheric and soil data collected at the site provide useful information for predicting future site performance at the RWMS

  13. An Evaluation of Unsaturated Flow Models in an Arid Climate

    Energy Technology Data Exchange (ETDEWEB)

    Dixon, J.

    1999-12-01

    The objective of this study was to evaluate the effectiveness of two unsaturated flow models in arid regions. The area selected for the study was the Area 5 Radioactive Waste Management Site (RWMS) at the Nevada Test Site in Nye County, Nevada. The two models selected for this evaluation were HYDRUS-1D [Simunek et al., 1998] and the SHAW model [Flerchinger and Saxton, 1989]. Approximately 5 years of soil-water and atmospheric data collected from an instrumented weighing lysimeter site near the RWMS were used for building the models with actual initial and boundary conditions representative of the site. Physical processes affecting the site and model performance were explored. Model performance was based on a detailed sensitivity analysis and ultimately on storage comparisons. During the process of developing descriptive model input, procedures for converting hydraulic parameters for each model were explored. In addition, the compilation of atmospheric data collected at the site became a useful tool for developing predictive functions for future studies. The final model results were used to evaluate the capacities of the HYDRUS and SHAW models for predicting soil-moisture movement and variable surface phenomena for bare soil conditions in the arid vadose zone. The development of calibrated models along with the atmospheric and soil data collected at the site provide useful information for predicting future site performance at the RWMS.

  14. Styles and rates of long-term denudation in carbonate terrains under a Mediterranean to hyper-arid climatic gradient

    Science.gov (United States)

    Ryb, U.; Matmon, A.; Erel, Y.; Haviv, I.; Benedetti, L.; Hidy, A. J.

    2014-11-01

    Carbonate minerals, unlike silicates, have the potential to dissolve almost completely and with high efficiency. Thus, in carbonate terrains denudation rate and style (the governing process of denudation, mechanical or chemical) should be more sensitive to climatic forcing. Using 36Cl measurements in 39 carbonate bedrock and sediment samples, we calculate long-term denudation rates across a sharp climatic gradient from Mediterranean to hyper-arid conditions. Our samples were collected along the Arugot watershed, which drains the eastern flank of the Judea Range (central Israel) to the Dead Sea and is characterized by a pronounced rain shadow. Denudation rates of flat-lying bedrock outcrops sampled along interfluves differ by an order of magnitude from ∼20 mm ka-1 in the Mediterranean zone to 1-3 mm ka-1 in the hyper-arid zone. These rates are strongly correlated with precipitation, and thus reflect the importance of carbonate mineral dissolution in the overall denudation process. In contrast, denudation rates of steep bedrock surfaces depend on the hillslope gradient, but only in the hyper-arid climate zone, indicating that mechanical processes dominate the overall hillslope denudation within this zone. The dominance of slope-dependent mechanical erosion in the hyper-arid zone is also reflected by an increase in spatially-average denudation rates from 17-19 mm ka-1 in the Mediterranean-semi-arid zones to 21-25 mm ka-1 in the hyper-arid zone. These higher rates are attributed to clast contribution from steep slopes under arid climate. This suggests an increased importance of mechanical processes to the overall denudation in the hyper-arid zone. We demonstrate that the transition between chemically-dominated denudation to mechanically-dominated denudation occurs between 100 and 200 mm of mean annual precipitation. Long-term denudation rates across the Judea Range indicate that between Mediterranean and hyper-arid climates, chemical weathering rates are limited by

  15. Semi-arid vegetation response to antecedent climate and water balance windows

    Science.gov (United States)

    Thoma, David P.; Munson, Seth M.; Irvine, Kathryn M.; Witwicki, Dana L.; Bunting, Erin

    2016-01-01

    Questions Can we improve understanding of vegetation response to water availability on monthly time scales in semi-arid environments using remote sensing methods? What climatic or water balance variables and antecedent windows of time associated with these variables best relate to the condition of vegetation? Can we develop credible near-term forecasts from climate data that can be used to prepare for future climate change effects on vegetation? Location Semi-arid grasslands in Capitol Reef National Park, Utah, USA. Methods We built vegetation response models by relating the normalized difference vegetation index (NDVI) from MODIS imagery in Mar–Nov 2000–2013 to antecedent climate and water balance variables preceding the monthly NDVI observations. We compared how climate and water balance variables explained vegetation greenness and then used a multi-model ensemble of climate and water balance models to forecast monthly NDVI for three holdout years. Results Water balance variables explained vegetation greenness to a greater degree than climate variables for most growing season months. Seasonally important variables included measures of antecedent water input and storage in spring, switching to indicators of drought, input or use in summer, followed by antecedent moisture availability in autumn. In spite of similar climates, there was evidence the grazed grassland showed a response to drying conditions 1 mo sooner than the ungrazed grassland. Lead times were generally short early in the growing season and antecedent window durations increased from 3 mo early in the growing season to 1 yr or more as the growing season progressed. Forecast accuracy for three holdout years using a multi-model ensemble of climate and water balance variables outperformed forecasts made with a naïve NDVI climatology. Conclusions We determined the influence of climate and water balance on vegetation at a fine temporal scale, which presents an opportunity to forecast vegetation

  16. Heterogeneous aquifer system modelisation under semi-arid climate

    Science.gov (United States)

    Drias, Tarek; Toubal, Ahmed Cherif

    2010-05-01

    The studied zone is a part of the Mellegne's (North-East of Algeria) under pound, this zone is characterised by its semi-arid climate. The water bearing system is formed by the plio-quaternairy alluviums resting on a marley substratuim of age Eocene. The geostatiscitcs approach of the hydrodynamics parameters (Hydrolic load, transmisivity) allowed the study of their spatial distrubution (casting) by the method of Krigeage by blocks and the identification of zones with water-bearing potentialities. In this respect, the zone of Ain Chabro which, is situated in the South of the plain shows the best values of the transmisivity...... The use of a bidimensinnel model in the differences ended in the permanent regime allowed us to establish the global balence sheet (overall assessment) of the tablecloth and to refine the transmisivity field. These would vary more exactley between 10-4 to 10-2 m²/s. The method associating the probability appraoch of Krigeage to that determining the model has facilited the wedging of the model and clarified the inflitration value. Keys words: hydrodynamics, geostatiscitcs, Modeling, Chabro, Tébessa.

  17. Climate change in semi-arid Malawi: Perceptions, adaptation strategies and water governance

    Directory of Open Access Journals (Sweden)

    Miriam K. Joshua

    2016-03-01

    Full Text Available Climate change and variability are a threat to sustainable agricultural production in semi-arid areas of Malawi. Overdependence on subsistence rain-fed agriculture in these areas calls for the identification of sustainable adaptation strategies. A study was therefore conducted in Chikwawa, a semi-arid district in southern Malawi, to: (1 assess community’s perception of a changing climate against empirical evidence, (2 determine their local adaptive measures, (3 evaluate the potential of irrigated agriculture as an adaptive measure in household food security and (4 challenges over access to available water resources. The study employed focus group discussions and key informant interviews to assess people’s perceptions of climate change and variability and their desired interventions. To validate the people’s perceptions, rainfall and temperature data for the period 1960–2010 were analysed. A participatory complete randomised experimental design in both rain-fed and dry season–irrigated conditions was conducted to assess a maize cropping system that would improve adaptation. The study established persistent declining yields from rain-fed production in part because of perennial rainfall failure. In response, the community has shifted its focus to irrigation as an adaptation strategy, which has in turn triggered water conflicts in the community over the control of the resource. Water legislation however fails to adequately provide for rules governing sharing of water resources between various stakeholders. This article therefore recommends development of an appropriate institutional framework that forms a strong basis for equitable distribution of water for irrigation in areas most vulnerable to extreme climate events – including droughts and floods.Keywords: Food Security; Climate Change and Variability; Rainfall Variability; Irrigation; Water Resources; Governance Crisis

  18. Modeling the Hydrological Response to Climate Change in an Arid Inland River Basin

    Science.gov (United States)

    Zheng, C.; Zhang, A.; Tian, Y.; Zheng, Y.; Liu, J.

    2014-12-01

    Located deep in the hinterlands of Eurasia, the Heihe River Basin (HRB) is an arid inland river basin in northwest China where the hydrologic regime responds sensitively to climate change. From the headwater region to terminal lakes, the HRB can be roughly divided into three sections, i.e., the upstream Qilian Mountains, the midstream oases and the downstream Gobi Desert. Runoff generated in the upstream mountainous terrains, dominated by climate variations, is the critical water resource for the whole river basin. With increasing intensification of climate change, there is an urgent need to understand future changes of water resources and water-related disasters to support regional water management. This study investigates the potential impact of climate change on hydrologic processes in the upper HRB for the future period of 2021~2150. Downscaled temperature and precipitation projections from six General Circulation Models under two emission scenarios (RCP4.5 and RCP8.5) are adopted to drive a commonly used flow model, Soil Water Assessment Tool (SWAT), for the upper HRB. The impacts of climate change on the total runoff and its components are quantified based on the future climate scenario analysis and the results of SWAT simulation. To understand how the climate change affects the availability and distribution of water resources in the middle and lower HRB where irrigated agriculture and ecosystem conservation compete for water resources, runoffs from the upper HRB are used as the boundary conditions for an integrated groundwater-surface water model based on the USGS GSFLOW for the middle and lower HRB. The integrated model assimilated multiple types of data including groundwater levels at monitoring wells, streamflow at gaging stations, and evapotranspiration (ET) derived from remote sensing data. The calibrated model was able to adequately reproduce the observed hydrological variables. The integrated model was then used to assess the potential response of the

  19. An Overview of the Semi-arid Climate and Environment Research Observatory over the Loess Plateau

    Institute of Scientific and Technical Information of China (English)

    HUANG Jianping; ZHANG Seidou; WANG Guoyin; FENG Guanghong; YUAN Jiuyi; ZHANG Lei; ZUO Hongchao; WANG Shigong; FU Congbin; CHOU Jifan; ZHANG Wu; ZUO Jinqing; BI Jianrong; SHI Jinsen; WANG Xin; CHANG Zhoulin; HUANG Zhongwei; YANG Su

    2008-01-01

    Arid and semi-arid areas comprise about 30% of the earth's surface. Changes in climate and climate variability will likely have a significant impact on these regions. The Loess Plateau over Northwest China is a special semi-arid land surface and part of a dust aerosol source. To improve understanding and capture the direct evidence of the impact of human activity on the semi-arid climate over the Loess Plateau, the Semi-Arid Climate and Environment Observatory of Lanzhou University (SACOL) was established in 2005. SACOL consists of a large set of instruments and focuses on: (1) monitoring of long term tendencies in semiarid climate changes; (2) monitoring of the aerosol effect on the water cycle; (3) studies of interaction between land surface and the atmosphere; (4) improving the land surface and climate models; and (5) validation of space-borne observations. This paper presents a description of SACOL objectives, measurements, and sampling strategies. Preliminary observation results are also reviewed in this paper.

  20. Evidence of Urban-Induced Precipitation Variability in Arid Climate Regimes

    Science.gov (United States)

    Shepherd, J. Marshall

    2005-01-01

    Water is essential to life in the Earth system. The water cycle components that sustain life are becoming more scarce and polluted. The most recent (1999-2004) drought experienced in the southwestern United States is the seventh worst in the approximately 500-year proxy tree-ring record. As a result, many regions contemplated drought emergencies in which severe water restrictions are implemented. Though larger weather and climate processes likely control drought processes, there is increasing evidence that anthropogenic or human-related activities can significantly alter precipitation processes. Urbanization is an example of anthropogenic forcing. Recent studies continue to provide evidence that urban environments can modify or induce precipitation under a specific set of conditions. Arid and semi-arid regions of the southwestern United States and other parts of the world are rapidly developing and placing greater demands on the environmental system. In the past fifty years, Phoenix has expanded from a predominantly agricultural center to an urbanized region with extent 700 percent larger than its size in the middle of the twentieth century. Riyadh's population grew from about a half million people in 1972 to almost two million by 2000. Saudi Arabia experienced urbanization later than many other countries; in the early 1970s its urban-rural ratio was still about 1:3. By 1990 the ratio had reversed to about 3:l. In the mid-1970s Riyadh's population was increasing by about 10 percent a year. Irrigation also significantly increased between 1972 and 1990 southeast of Riyadh. The study employs a 108-year precipitation historical data record, global climate observing network observations and satellite data to identify possible anomalies in rainfall in and around two major arid urban areas, Phoenix, Arizona and Riyadh, Saudi Arabia. It provides statistically sound evidence that rainfall distribution and magnitude is statistically different in post-urban than in pre

  1. Agronomic evaluation of barley mutants under semi-arid conditions

    International Nuclear Information System (INIS)

    A mutant line, Cyp M9, selected from a population of the barley variety Attiki treated with gamma rays, was evaluated against commercial varieties for the grain yield, yield components, and the protein content and yield in 15 trials. The grain yield of Cyp M9 was 14% higher than that of its mother variety, Attiki, and similar to those of the best commercial varieties, Athenais and Kantara. The protein yield of the mutant line (711 kg/ha) was higher than those of the commercial varieties. Regression analyses of the varietal grain yield and the environmental mean showed that the response of Cyp M9 to improved environmental conditions was greater than those of the commercial varieties. Furthermore, Cyp M9 showed a better response to higher rainfall conditions than Kantara. In general, the mutant Cyp M9 responded to environmental changes in the semi-arid environment in a manner similar to, or better than, those of the commercial varieties. (author). 5 refs, 1 fig., 1 tab

  2. Quantitative Prediction Study of Climate-sensitive Potassium with Hyperspectrum in Arid and Semi-arid Region of Northwestern China

    International Nuclear Information System (INIS)

    Soil potassium content in arid and semi-arid region can reflect the conditions of the paleoclimate and it can be inverted by soil spectra. The relationship between soil spectra and soil potassium content was discussed in this research. Based on four reflectance transformations, single-variance analysis and multi-variances inversion model were built to invert potassium content. The results of single-wavelength inversions were very significant except for the reflectance model. The multi-variances models were good and accurately (R2 (determination coefficient) >0.674 and RMSE (root-mean-square error) <0.09). Then, the sensitive wavelengths of the potassium were chosen by using the higher correlation coefficients. The results of this study showed that both methods have a great potential for predicting soil potassium content. The sensitive wavelengths of the potassium content were at 2200–2300 nm which could be illustrated by the potassium-bearing minerals spectral absorption features

  3. Climatic Conditions in Classrooms.

    Science.gov (United States)

    Kevan, Simon M.; Howes, John D.

    1980-01-01

    Presents an overview of research on the ways in which classroom thermal environment, lighting conditions, ion state, and electromagnetic and air pollution affect learning and the performance of students and teachers. (SJL)

  4. Retreating or standing: responses of forest species and steppe species to climate change in arid Eastern Central Asia.

    Directory of Open Access Journals (Sweden)

    Hong-Xiang Zhang

    Full Text Available BACKGROUND: The temperature in arid Eastern Central Asia is projected to increase in the future, accompanied by increased variability of precipitation. To investigate the impacts of climate change on plant species in this area, we selected two widespread species as candidates, Clematis sibirica and C. songorica, from montane coniferous forest and arid steppe habitats respectively. METHODOLOGY/PRINCIPAL FINDINGS: We employed a combined approach of molecular phylogeography and species distribution modelling (SDM to predict the future responses of these two species to climate change, utilizing evidence of responses from the past. Genetic data for C. sibirica shows a significant phylogeographical signal (N ST > F ST, P<0.05 and demographic contraction during the glacial-interglacial cycles in the Pleistocene. This forest species would likely experience range reduction, though without genetic loss, in the face of future climate change. In contrast, SDMs predict that C. songorica, a steppe species, should maintain a consistently stable potential distribution under the Last Glacial Maximum (LGM and the future climatic conditions referring to its existing potential distribution. Molecular results indicate that the presence of significant phylogeographical signal in this steppe species is rejected and this species contains a high level of genetic differentiation among populations in cpDNA, likely benefiting from stable habitats over a lengthy time period. CONCLUSIONS/SIGNIFICANCE: Evidence from the molecular phylogeography of these two species, the forest species is more sensitive to past climate changes than the steppe species. SDMs predict that the forest species will face the challenge of potential range contraction in the future more than the steppe species. This provides a perspective on ecological management in arid Eastern Central Asia, indicating that increased attention should be paid to montane forest species, due to their high sensitivity to

  5. A study on environmental aridity over northern and southern to Qinling Mountains under climate warming

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Based on the data up to 1999 from hydroclimatological departments, this paper analyzes the climatic divide implications of the Qinling Mountains in regional response to the process of climate warming, due to which the grades of dryness/wetness (GDW) in 100 years show that the northern region has entered a drought period, while the southern is a humid period. In a course of ten years, the D-value of annual average air temperature over southern Shaanxi (the Hanjiang Valley) and the Central Shaanxi Plain (the Guanzhong Plain) has narrowed, i.e., the former with a slight change and the latter with rapid increase in temperature. Both regions were arid with the decrease in precipitation D-value, namely the plain became warmer while the south was drier. The Qinling Mountains play a pronounced role in the climatic divide. The runoff coefficient (RC) of the Weihe River decreases synchronously with that of the Hanjiang due to climate warming. The RC of Weihe dropped from 0.2 in the 1950s to less than 0.1 in the 1990s. The Weihe Valley (the Guanzhong Plain) is practically an arid area due to shortage of water. The successive 0.5, 1.0℃ temperature anomaly over China marks, perhaps, the important transition period in which the environment becomes more vulnerable than before.The study shows the obvious trend of environmental aridity, which is of help to the understanding of regional response to global climate change.

  6. Designing of zero energy office buildings in hot arid climate

    Energy Technology Data Exchange (ETDEWEB)

    Abdel-Gwad, Mohamed

    2011-07-01

    The designing of office buildings by using large glass areas to have a transparent building is an attractive approach in the modern office building architecture. This attitude increases the energy demand for cooling specially in the hot arid region which has long sun duration time, while the use of small glazing areas increases the energy demand for lighting. The use of uncontrolled natural ventilation increases the rate of hot ambient air flow which increases the building energy demand for cooling. At the same time, the use of mechanical ventilation to control the air change rate may increase the energy demand for fans. Some ideas such as low energy design concept are introduced for improving the building energy performance and different rating systems have been developed such as LEED, BREEAM and DGNB for evaluating building energy performance system. One of the new ideas for decreasing the dependence on fossil fuels and improving the use of renewable energy is the net zero-energy building concept in which the building generates enough renewable energy on site to equal or exceed its annual energy use. This work depends on using the potentials of mixing different energy strategies such as hybrid ventilation strategy, passive night cooling, passive chilled ceiling side by side with the integrating of photovoltaic modules into the building facade to produce energy and enrich the architectural aesthetics and finally reaching the Net Zero Energy Building. There are different definitions for zero energy buildings, however in this work the use of building-integrated Photovoltaic (BIPV) to provide the building with its annual energy needs is adopted, in order to reach to a Grid-Connected Net-Zero Energy Office Building in the hot arid desert zone represented by Cairo, Egypt. (orig.)

  7. A Framework Predicting Water Availability in a Rapidly Growing, Semi-Arid Region under Future Climate Change

    Science.gov (United States)

    Han, B.; Benner, S. G.; Glenn, N. F.; Lindquist, E.; Dahal, K. R.; Bolte, J.; Vache, K. B.; Flores, A. N.

    2014-12-01

    Climate change can lead to dramatic variations in hydrologic regime, affecting both surface water and groundwater supply. This effect is most significant in populated semi-arid regions where water availability are highly sensitive to climate-induced outcomes. However, predicting water availability at regional scales, while resolving some of the key internal variability and structure in semi-arid regions is difficult due to the highly non-linearity relationship between rainfall and runoff. In this study, we describe the development of a modeling framework to evaluate future water availability that captures elements of the coupled response of the biophysical system to climate change and human systems. The framework is built under the Envision multi-agent simulation tool, characterizing the spatial patterns of water demand in the semi-arid Treasure Valley area of Southwest Idaho - a rapidly developing socio-ecological system where urban growth is displacing agricultural production. The semi-conceptual HBV model, a population growth and allocation model (Target), a vegetation state and transition model (SSTM), and a statistically based fire disturbance model (SpatialAllocator) are integrated to simulate hydrology, population and land use. Six alternative scenarios are composed by combining two climate change scenarios (RCP4.5 and RCP8.5) with three population growth and allocation scenarios (Status Quo, Managed Growth, and Unconstrained Growth). Five-year calibration and validation performances are assessed with Nash-Sutcliffe efficiency. Irrigation activities are simulated using local water rights. Results show that in all scenarios, annual mean stream flow decreases as the projected rainfall increases because the projected warmer climate also enhances water losses to evapotranspiration. Seasonal maximum stream flow tends to occur earlier than in current conditions due to the earlier peak of snow melting. The aridity index and water deficit generally increase in the

  8. Drought Forecasting Using Stochastic Models in a Hyper-Arid Climate

    OpenAIRE

    Amr Mossad; Abdulrahman Ali Alazba

    2015-01-01

    Drought forecasting plays a crucial role in drought mitigation actions. Thus, this research deals with linear stochastic models (autoregressive integrated moving average (ARIMA)) as a suitable tool to forecast drought. Several ARIMA models are developed for drought forecasting using the Standardized Precipitation Evapotranspiration Index (SPEI) in a hyper-arid climate. The results reveal that all developed ARIMA models demonstrate the potential ability to forecast drought over different time ...

  9. Climate change and water storage variability over an arid endorheic region

    Science.gov (United States)

    Yang, Tao; Wang, Chao; Chen, Yaning; Chen, Xi; Yu, Zhongbo

    2015-10-01

    Terrestrial Water Storage (TWS) plays an important role in regional climate and water resources management, especially in arid regions under global change context. However, serious lack of in-situ measurements in remote alpine mountains is hindering our current understanding of regional TWS change in the Tarim River Basin (TRB), a large and typical arid endorheic area in Northwest China of Central Asia. To solve the problem, four different hydrology products from the Gravity Recovery and Climate Experiment (GRACE) satellite, model simulations from Global Land Data Assimilation System (GLDAS) in conjunction with in-situ measurements, are utilized to investigate patterns and underlying causes of TWS and its component changes. An excess of precipitation over evapotranspiration (ET) plus runoff contributes to an increase of TWS. The phase of Total Soil Moisture (TSM) lags that of Snow Water Equivalent (SWE), indicating a recharge from snowmelt to TSM. Increasing TWS together with decreasing SWE resulted in an increase of subsurface water. Our results are of great value to amend basin-wide water management and conservation strategies for the similar arid regions considering climate change.

  10. Predicting the Affects of Climate Change on Evapotranspiration and Agricultural Productivity of Semi-arid Basins

    Science.gov (United States)

    Peri, L.; Tyler, S. W.; Zheng, C.; Pohll, G. M.; Yao, Y.

    2013-12-01

    Many arid and semi-arid regions around the world are experiencing water shortages that have become increasingly problematic. Since the late 1800s, upstream diversions in Nevada's Walker River have delivered irrigation supply to the surrounding agricultural fields resulting in a dramatic water level decline of the terminal Walker Lake. Salinity has also increased because the only outflow from the lake is evaporation from the lake surface. The Heihe River basin of northwestern China, a similar semi-arid catchment, is also facing losses from evaporation of terminal locations, agricultural diversions and evapotranspiration (ET) of crops. Irrigated agriculture is now experiencing increased competition for use of diminishing water resources while a demand for ecological conservation continues to grow. It is important to understand how the existing agriculture in these regions will respond as climate changes. Predicting the affects of climate change on groundwater flow, surface water flow, ET and agricultural productivity of the Walker and Heihe River basins is essential for future conservation of water resources. ET estimates from remote sensing techniques can provide estimates of crop water consumption. By determining similarities of both hydrologic cycles, critical components missing in both systems can be determined and predictions of impacts of climate change and human management strategies can be assessed.

  11. Early Pleistocene climate in western arid central Asia inferred from loess-palaeosol sequences

    Science.gov (United States)

    Wang, Xin; Wei, Haitao; Taheri, Mehdi; Khormali, Farhad; Danukalova, Guzel; Chen, Fahu

    2016-02-01

    Arid central Asia (ACA) is one of the most arid regions in the mid-latitudes and one of the main potential dust sources for the northern hemisphere. The lack of in situ early Pleistocene loess/dust records from ACA hinders our comprehensive understanding of the spatio-temporal record of aeolian loess accumulation and long term climatic changes in Asia as a whole. Here, we report the results of sedimentological, chronological and climatic studies of early Pleistocene loess-palaeosol sequences (LPS) from the northeastern Iranian Golestan Province (NIGP) in the western part of ACA. Our results reveal that: 1) Accumulation of loess on the NIGP commenced at ~2.4-1.8 Ma, making it the oldest loess known so far in western ACA; 2) the climate during the early Pleistocene in the NIGP was semi-arid, but wetter, warmer, and less windy than during the late Pleistocene and present interglacial; 3) orbital-scale palaeoclimatic changes in ACA during the early Pleistoceneare in-phase with those of monsoonal Asia, a relationship which was probably related to the growth and decay of northern hemisphere ice sheets.

  12. Bioclimatic landscape design in extremely hot and arid climates

    OpenAIRE

    Attia, Shady; Duchhart, Ingrid

    2011-01-01

    In the desert the role of bioclimatic landscape design is to consider three major environmental factors, solar radiation, evaporation, wind and air flows. Therefore the landscape architect should be prepared with a group of design principals and design guidelines that can help him to improve the micro-climate and conserve energy. This paper presents a group of passive design strategies for bioclimatic landscape architecture in the desert. In this study, a bioclimatic landscape design strategy...

  13. Biomimicry as an approach for sustainable architecture case of arid regions with hot and dry climate

    Science.gov (United States)

    Bouabdallah, Nabila; M'sellem, Houda; Alkama, Djamel

    2016-07-01

    This paper aims to study the problem of thermal comfort inside buildings located in hot and arid climates. The principal idea behind this research is using concepts based on the potential of nature as an instrument that helps creating appropriate facades with the environment "building skin". The biomimetic architecture imitates nature through the study of form, function, behaviour and ecosystems of biological organisms. This research aims to clarify the possibilities that can be offered by biomimicry architecture to develop architectural bio-inspired building's design that can help to enhance indoor thermal ambiance in buildings located in hot and dry climate which helps to achieve thermal comfort for users.

  14. Impact of climate change on arid lands agriculture

    Directory of Open Access Journals (Sweden)

    El-Beltagy Adel

    2012-04-01

    Full Text Available Abstract The planet earth, on which we live in communities, is being increasingly 'ruptured' because of human activities; its carrying capacity is under great stress because of demographic pressures. The pressure is especially affecting the people living in the dry areas because of the marginal and fragile nature of the resources they have access to. There are over 2,000 million hectares of land that have been degraded, with a loss of agrobiodiversity, increased water scarcity and increased natural resource destruction. Superimposed on this is the fact that the neglectful and exploitive use of natural resources has set the train of global climate change in motion. It is anticipated that the impact of climate change will cut across all boundaries. Crops, cropping systems, rotations and biota will undergo transformation. To maintain the balance in the system, there is a need for new knowledge, alternative policies and institutional changes. The marginalized people in dry areas are likely to be most seriously hit by the shifts in moisture and temperature regimes as a result of the global climate change. To help them cope with the challenges, there is a need for a new paradigm in agricultural research and technology transfer that makes full use of modern science and technology in conjunction with traditional knowledge. This necessitates more investment by international agencies and national governments for supporting the relevant integrated research and sustainable development efforts, with full participation of the target communities. Only such an approach can enable the vulnerable communities of the dryland areas to use the natural resources in a sustainable manner and thus help protect the environment for future generations. The clock is ticking and the future of the world lies in the collective responsibility and wisdom of all nations on this planet. This should be reflected in the endorsement of a solid future plan.

  15. Satellite-Based Monitoring of Decadal Soil Salinization and Climate Effects in a Semi-arid Region of China

    Institute of Scientific and Technical Information of China (English)

    WANG Hesong; JIA Gensuo

    2012-01-01

    Soil salinization is a common phenomenon that affects both the environment and the socio-economy in arid and semi-arid regions; it is also an important aspect of land cover change.In this study,we integrated multi-sensor remote sensing data with a field survey to analyze processes of soil salinization in a semi-arid area in China from 1979 to 2009. Generally,the area of salt-affected soils increased by 0.28% per year with remarkable acceleration from 1999 to 2009 (0.42% increase per year).In contrast,the area of surface water bodies showed a decreasing trend (-0.08% per year) in the same period.Decreases in precipitation and increases in aridity due to annual (especially summer) warming provided a favorable condition for soil salinization. The relatively flat terrain favored waterlogging at the surface,and continuous drought facilitated upward movement of soil water and accumulation of surface saline and calcium. Meanwhile,land-use practices also played a crucial role in accelerating soil salinization.The conversion to cropland from natural vegetation greatly increased the demand for groundwater irrigation and aggravated the process of soil salinization.Furthermore,there are potential feedbacks of soil salinization to regional climate.The salinization of soils can limit the efficiency of plant water use as well as photosynthesis; therefore,it reduces the amount of carbon sequestrated by terrestrial ecosystem.Soil salinization also reduces the absorbed solar radiation by increasing land surface albedo.Such conversions of land cover significantly change the energy and water balance between land and atmosphere.

  16. Book Review: Late Cenozoic Climate Change in Asia: Loess, Monsoon and Monsoon-arid Environment Evolution

    Science.gov (United States)

    Clemens, Steven C.

    2015-01-01

    Loess-Paleosol deposits drape >500,000 km2 of eastern China, spanning environments from the humid, monsoon-influenced regions near the coast to the arid, westerlies-dominated regions inland. Sections, up to hundreds of meters thick, are exposed in deeply incised river valleys and can be accessed as well by drilling. Combined, the high sedimentation rates and extensive geographic coverage make these sections unique among global terrestrial sediment archives. The Chinese loess-paleosol sequences, and the arid interior regions to the northwest, record diverse aspects of geologic and environmental change ranging from the tectonic evolution of the Tibetan Plateau (106 year time scale) through glacial-interglacial scale changes in global ice volume and greenhouse gasses (105 year time scale) on down through the orbital (104 years) to millennial and centennial scale events (103-102 year) relevant to the underpinnings of human interactions with changing environmental pressures. 'Late Cenozoic Climate Chang in Asia: Loess, Monsoon and Monsoon-arid Environment Evolution' is a timely contribution that synthesizes findings derived from the extensive work in these areas, places the findings in the broader context of global climate change and helps to define avenues for future research.

  17. Analysis of behaviour patterns and thermal responses to a hot-arid climate in rural China.

    Science.gov (United States)

    Yan, Haiyan; Yang, Liu; Zheng, Wuxing; He, Wenfang; Li, Daoyi

    2016-07-01

    Climate can greatly affect building design, life style and thermal perception for all groups of people; however, this phenomenon has not yet been rigorously evaluated in China's hot-arid climate. The aim of this paper is to present the results of a thermal comfort survey by evaluating the influence of the hot-arid climate upon the behavioural patterns and thermal comfort responses of 160 residents in 65 traditional vernacular houses in Turfan, China, in 2011. In this survey, there were 206 sets of effective data, and the features of the traditional residential buildings and the human behaviour patterns in Turfan were described and analysed. The results showed that the diversified courtyards and shade spaces were the most obvious features of traditional houses in Turfan. People here typically spend most of their time in one of two spaces for eating, resting, and entertaining. It was found that the preferred temperature was 26.5°C. The preferred air velocity occurred at 0.62m/s. A suitable air velocity range of 0.15-1.24m/s was suggested in Turfan. Moreover, the neutral temperature of the local people was 30.1°C (tg or to). The upper limits of the 80% acceptable zone by using the direct and indirect acceptability method were 32.7 and 33.8°C, respectively. The neutral temperature and upper limit of the acceptable zone in Turfan were higher than those of the adaptive standards. Attention should be paid to the role of thermal comfort in influencing building design by using simple passive cooling strategies. The above results are believed to be potentially valuable for the design and evaluation of residential buildings located in hot-arid climate. PMID:27264894

  18. A fitful fungus from a hot, arid climate increases grain yield in cool-cultivated barley

    OpenAIRE

    Murphy, Brian R.; Fiona M Doohan; HODKINSON, TREVOR R.

    2014-01-01

    Purpose The fungus Piriformospora indica was first isolated from plants growing in arid, hot desert conditions and has been shown to have significant potential as a biocontrol and biofertilising organism in barley under optimal growth conditions. However, it was not thought to be effective in plants grown in low temperatures and has consequently not been well tested in cold-stressed crops. This study sought to determine the effects of inoculating barley plants with this f...

  19. Simulated response of groundwater to predicted recharge in a semi-arid region using a scenario of modelled climate change

    International Nuclear Information System (INIS)

    Groundwater systems in arid regions will be particularly sensitive to climate change owing to the strong dependence of rates of evapotranspiration on temperature, and shifts in the precipitation regimes. In agricultural areas, such changes in climate may require increased irrigation, putting stress on existing water supplies. In this study, a regional-scale numerical groundwater model was developed for the Oliver region of the south Okanagan, British Columbia, Canada, to simulate the impacts of future predicted climate change on groundwater. In future time periods (the 2050s and 2080s), the most noticeable change in the water budget is the increased contribution of recharge to the annual water budget, estimated at 1.2% (2050s) and 1.4% (2080s) of the total annual budget relative to the current conditions. This increase is related primarily to increases to irrigation return flow resulting from higher irrigation needs under warmer temperatures and a longer growing season. Increases in recharge and irrigation return flow will result in higher water tables with future climate conditions, particularly in the irrigation districts. Median value increases in groundwater level of up to 0.7 m by the 2080s are estimated.

  20. Application of a stochastic weather generator to assess climate change impacts in a semi-arid climate: The Upper Indus Basin

    Science.gov (United States)

    Forsythe, N.; Fowler, H. J.; Blenkinsop, S.; Burton, A.; Kilsby, C. G.; Archer, D. R.; Harpham, C.; Hashmi, M. Z.

    2014-09-01

    Assessing local climate change impacts requires downscaling from Global Climate Model simulations. Here, a stochastic rainfall model (RainSim) combined with a rainfall conditioned weather generator (CRU WG) have been successfully applied in a semi-arid mountain climate, for part of the Upper Indus Basin (UIB), for point stations at a daily time-step to explore climate change impacts. Validation of the simulated time-series against observations (1961-1990) demonstrated the models' skill in reproducing climatological means of core variables with monthly RMSE of operating in this mountainous context at the boundary between monsoonal and mid-latitude (westerly) weather systems. Of equal importance the model captures well the observed interannual variability as quantified by the first and last decile of 30-year climatic periods. Differences between a control (1961-1990) and future (2071-2100) regional climate model (RCM) time-slice experiment were then used to provide change factors which could be applied within the rainfall and weather models to produce perturbed ‘future' weather time-series. These project year-round increases in precipitation (maximum seasonal mean change:+27%, annual mean change: +18%) with increased intensity in the wettest months (February, March, April) and year-round increases in mean temperature (annual mean +4.8 °C). Climatic constraints on the productivity of natural resource-dependent systems were also assessed using relevant indices from the European Climate Assessment (ECA) and indicate potential future risk to water resources and local agriculture. However, the uniformity of projected temperature increases is in stark contrast to recent seasonally asymmetrical trends in observations, so an alternative scenario of extrapolated trends was also explored. We conclude that interannual variability in climate will continue to have the dominant impact on water resources management whichever trajectory is followed. This demonstrates the need for

  1. Simulating the hydrologic impacts of land-cover and climate changes in a semi-arid watershed

    Science.gov (United States)

    Changes in climate and land cover are principal variables affecting watershed hydrology. This paper uses a cell-based model to examine the hydrologic impacts of climate and land cover changes in the semi-arid Lower Virgin River (LVR) watershed located upstream of Lake Mead, Nevad...

  2. Management of Brackish water for crop production under arid and semi-arid conditions

    International Nuclear Information System (INIS)

    For sustainable crop production, changing soil or water chemistry so as to counter the adverse effects of brackish water is a good option. This is normally accomplished by soil or water applied amendments such as gypsum. The other option of blending or cycling brackish and non-brackish water also has merits to reduce the potential hazards. The biological and organic amendments improve soil physical conditions which, otherwise, are expected to be deteriorated by the use of brackish water. Keeping this in view, a field experiment was conducted on a non saline-non sodic sandy loam soil (EC/sub e/ 1.31-1.76 dS m/sup -1/, pH = 8.47-8.61, SAR = 5.50-7.41, infiltration rate 0.6-0.8 cm/h, bulk density = 1.56-1.61 Mg m/sup -3/ for the upper 15 cm soil depth) to evaluate the growth response of cotton crop to different soil and water treatments. Treatments included: T/sub 1/ canal water), T/sub 2/ [tube well water (EC = 3.38 dS m/sup -1/, SAR = 16.43 and RSC = 5.57 mmol/sub c/ L/sup -1/)], T3 [cyclic use (alternate irrigations with canal and tube well waters)], T/sub 4/ (tube well water as such + FYM at the rate of 25 Mg ha/sup -1/annually) and T/sub 5/ (tube well water + gypsum at the rate of water gypsum requirement (WRSC to be decreased up to 00). During the first year of experimentation seed cotton yield was not significantly affected by the applied treatments and was in the decreasing order of: T/sub 3/ (2361 kg ha/sup -1/) > T/sub 4/ (2073 kg ha/sup -1/) > T 1 (2015 kg ha/sup -1/) > T/sub 5/ (2001 kg ha.1 and T 2 (1982 ha/sup -1/. Number of bolls picked per plant was in the decreasing order of: T 2 (33) > T/sub 4/ (32) > T/sub 1/ (31) > T/sub 3/ (30) and T/sub 5/ (26) with non-significant treatment differences. The pH, EC/sub e/ and SAR values remained below safe limits by this cotton (first) crop. (author)

  3. Impacts of Present and Future Climate Variability and Change on Agriculture and Forestry in the Arid and Semi-Arid Tropics

    International Nuclear Information System (INIS)

    The arid and semi-arid regions account for approximately 30% of the world total area and are inhabited by approximately 20% of the total world population. Issues of present and future climate variability and change on agriculture and forestry in the arid and semi-arid tropics of the world were examined and discussion under each of these issues had been presented separately for Asia, Africa and Latin America. Several countries in tropical Asia have reported increasing surface temperature trends in recent decades. Although, there is no definite trend discernible in the long-term mean for precipitation for the tropical Asian region, many countries have shown a decreasing trend in rainfall in the past three decades. African rainfall has changed substantially over the last 60 yr and a number of theoretical, modelling and empirical analyses have suggested that noticeable changes in the frequency and intensity of extreme events, including floods may occur when there are only small changes in climate. Climate in Latin America is affected by the El Nino-southern oscillation (ENSO) phases and there is a close relationship between the increase and decrease of rainfall depending upon the warm or cold phases of the phenomenon. Over land regions of Asia, the projected area-averaged annual mean warming is likely to be 1.6 ± 0.2C in the 2020s, 3.1 ± 0.3C in the 2050s, and 4.6 ± 0.4C in the 2080s and the models show high uncertainty in projections of future winter and summer precipitation. Future annual warming across Africa is projected to range from 0.2C per decade to more than 0.5C per decade, while future changes in mean seasonal rainfall in Africa are less well defined. In Latin America, projections indicate a slight increase in temperature and changes in precipitation. Impacts of climate variability and changes are discussed with suitable examples. Agricultural productivity in tropical Asia is sensitive not only to temperature increases, but also to changes in the nature

  4. Modeling water scarcity and droughts for policy adaptation to climate change in arid and semiarid regions

    Science.gov (United States)

    Kahil, Mohamed Taher; Dinar, Ariel; Albiac, Jose

    2015-03-01

    Growing water extractions combined with emerging demands for environment protection increase competition for scarce water resources worldwide, especially in arid and semiarid regions. In those regions, climate change is projected to exacerbate water scarcity and increase the recurrence and intensity of droughts. These circumstances call for methodologies that can support the design of sustainable water management. This paper presents a hydro-economic model that links a reduced form hydrological component, with economic and environmental components. The model is applied to an arid and semiarid basin in Southeastern Spain to analyze the effects of droughts and to assess alternative adaptation policies. Results indicate that drought events have large impacts on social welfare, with the main adjustments sustained by irrigation and the environment. The water market policy seems to be a suitable option to overcome the negative economic effects of droughts, although the environmental effects may weaken its advantages for society. The environmental water market policy, where water is acquired for the environment, is an appealing policy to reap the private benefits of markets while protecting ecosystems. The current water management approach in Spain, based on stakeholders' cooperation, achieves almost the same economic outcomes and better environmental outcomes compared to a pure water market. These findings call for a reconsideration of the current management in arid and semiarid basins around the world. The paper illustrates the potential of hydro-economic modeling for integrating the multiple dimensions of water resources, becoming a valuable tool in the advancement of sustainable water management policies.

  5. Analyzing and modelling of flow transmission processes in river-systems with a focus on semi-arid conditions

    OpenAIRE

    Cunha Costa, Alexandre

    2012-01-01

    One of the major problems for the implementation of water resources planning and management in arid and semi-arid environments is the scarcity of hydrological data and, consequently, research studies. In this thesis, the hydrology of dryland river systems was analyzed and a semi-distributed hydrological model and a forecasting approach were developed for flow transmission processes in river-systems with a focus on semi-arid conditions. Three different sources of hydrological data (streamflow ...

  6. Determining the relative importance of climatic drivers on spring phenology in grassland ecosystems of semi-arid areas.

    Science.gov (United States)

    Zhu, Likai; Meng, Jijun

    2015-02-01

    Understanding climate controls on spring phenology in grassland ecosystems is critically important in predicting the impacts of future climate change on grassland productivity and carbon storage. The third-generation Global Inventory Monitoring and Modeling System (GIMMS3g) normalized difference vegetation index (NDVI) data were applied to derive the start of the growing season (SOS) from 1982-2010 in grassland ecosystems of Ordos, a typical semi-arid area in China. Then, the conditional Granger causality method was utilized to quantify the directed functional connectivity between key climatic drivers and the SOS. The results show that the asymmetric Gaussian (AG) function is better in reducing noise of NDVI time series than the double logistic (DL) function within our study area. The southeastern Ordos has earlier occurrence and lower variability of the SOS, whereas the northwestern Ordos has later occurrence and higher variability of the SOS. The research also reveals that spring precipitation has stronger causal connectivity with the SOS than other climatic factors over different grassland ecosystem types. There is no statistically significant trend across the study area, while the similar pattern is observed for spring precipitation. Our study highlights the link of spring phenology with different grassland types, and the use of coupling remote sensing and econometric tools. With the dramatic increase in global change research, Granger causality method augurs well for further development and application of time-series modeling of complex social-ecological systems at the intersection of remote sensing and landscape changes. PMID:25487765

  7. Vegetation mosaics in arid Australia: linked roles for climate and soils

    Science.gov (United States)

    Dunkerley, D.

    2012-04-01

    It is widely considered that quasi-regular patterns in dryland soils and vegetation reflect a process of self-organisation. In such a view, the spatial patterns emerge from multiple interactions and feedbacks among the elements of the ecogeomorphic system. In arid western NSW, Australia, key elements affecting the self-organisation of strongly banded vegetation appear to include the extreme climatic variability (related to ENSO and other global climate phenomena) and the geomorphic history of the landscape, which involves major glacial-period accessions of exotic aeolian clays of the illite family, which exhibit very marked shrink-swell behaviour. The latter may be a prerequisite for pattern emergence, and the former a key driver of emergence. A cellular model of pattern emergence was driven by a timeseries of annual rainfalls exhibiting occasional marked wet La Niña years and also multi-year El Niño droughts, in order to explore how this climatic driver affects pattern emergence. Importantly, the model incorporated the effects of drying and contraction of the deeper subsoils during multi-year droughts. In the field, extreme soil desiccation is seen to result in widespread tension cracking and collapse of the surface soils into voids in the more clay rich, and more strongly contracted, subsoil. The collapse features maintain the water trapping efficiency of the vegetation groves even when the plant cover has declined greatly. Trapping efficiency remains low within intergroves, because the subsoils there are always relatively dry, owing to their impermeable soil surfaces. Modelling excluding soil collapse during drought showed much greater loss of groves and resultant changes in grove spacing that is not seen in long-term field monitoring data. This suggests that the variability of annual rainfalls (and not just the average climatic aridity) may actually confer stability on the banded vegetation communities via a little-explored linkage of soil and climatic

  8. The relative contribution of short-term versus long-term effects in shrub-understory species interactions under arid conditions.

    Science.gov (United States)

    Noumi, Zouhaier; Chaieb, Mohamed; Le Bagousse-Pinguet, Yoann; Michalet, Richard

    2016-02-01

    Plant-plant interactions (competition and facilitation) in terrestrial ecosystems include: (1) short-term effects, primarily quantified with experimental removals; and (2) long-term effects, mostly due to soil weathering processes, primarily quantified with observational methods. It has been argued that these effects are likely to vary in contrasting directions with increasing drought stress in arid systems. However, few studies have used appropriate methodology to assess both types of effects and their variation across nurse species and environmental conditions, in particular in arid systems. This knowledge is crucial for predicting variation in the mediating role of facilitation with climate change and assessing the importance of nurse effects in ecological restoration. In the arid climate of central-south Tunisia, understory species' biomass, abundance and composition and soil parameters were compared in shrub-control, shrub-removed and open areas for three shrub species and in two habitats with contrasting soil moisture conditions. Long-term effects were dominant, positive for all three shrub species and associated with increasing nutrient content in shrub patches. Short-term effects, mainly related to water consumption, were weaker, mostly negative and dependent on shrub species. Additionally, long-term effects were less positive and short-term effects more negative in the dry habitat than in the wet habitat. Our study provides evidence of the primary influence of positive (facilitative) long-term effects in this arid system. However, the net effects of shrubs could be less beneficial for other species with increasing aridity under climate change, due to both a decrease in positive long-term effects and an increase in negative short-term effects. PMID:26527462

  9. IMPLEMENTATION OF GREEN ROOF SUSTAINABILITY IN ARID CONDITIONS

    Science.gov (United States)

    We successfully designed and fabricated accurately scaled prototypes of a green roof and a conventional white roof and began testing in simulated conditions of 115-70°F with relative humidity of 13%. The design parameters were based on analytical models created through ver...

  10. Assessment of the desertification vulnerability of the Cappadocian district (Central Anatolia, Turkey based on aridity and climate-process system

    Directory of Open Access Journals (Sweden)

    Murat Türkeş

    2011-03-01

    Full Text Available The present study discusses climate of the Cappadocian district in Turkey on the basis of Thornthwaite’s climate classification and water budget, Erinç’s aridity index and United Nations Convention to Combat Desertification (UNCCD aridity index, along with the spatial and inter-seasonal variations of precipitation and air temperatures. Vulnerability of the Cappadocia to desertification processes was also investigated with respect to the aridity, lithology dominated by tuffs and climate-process system and present land-use features of the district. The data analysis revealed that coefficients of variation (CV of the mean and maximum temperatures are the greatest in summer and the smallest in winter. Nevşehir and Kayseri environs are the most continental parts of the Cappadocia with a high inter-annual variability and low temperatures. Cappadocia is characterized with a continental rainfall regime having a maximum precipitation in spring. Variability of summer precipitation totals is greater than that of other seasons, varying from 65.7% to 78%. The CVs of the annual precipitation totals are about 18% at north and about 20% at south. Semi-arid and dry sub-humid or semi-humid climate types prevail over Cappadocia according to Thornthwaite’s moisture and Erinç’s aridity indices. Steppe is the dominant vegetation formation with sparse dry trees. The Cappadocia is vulnerable to the desertification processes due to both natural factors (e.g. degree of aridity, climate-process system, weathering of tuffs, erosion, climate change, etc. and human-involvement (e.g. land degradation and intensive tourism, etc.. In order to mitigate desertification and to preserve the historical and cultural heritages in Cappadocia, sustainable land-use management and tourism planning applications are urgently needed.

  11. Assessment of the desertification vulnerability of the Cappadocian district (Central Anatolia, Turkey based on aridity and climate-process system

    Directory of Open Access Journals (Sweden)

    Murat Türkeş

    2011-03-01

    Full Text Available The present study discusses climate of the Cappadocian district in Turkey on the basis of Thornthwaite’s climate classification and water budget, Erinç’s aridity index and United Nations Convention to Combat Desertification (UNCCD aridity index, along with the spatial and inter-seasonal variations of precipitation and air temperatures. Vulnerability of the Cappadocia to desertification processes was also investigated with respect to the aridity, lithology dominated by tuffs and climate-process system and present land-use features of the district. The data analysis revealed that coefficients of variation (CV of the mean and maximum temperatures are the greatest in summer and the smallest in winter. Nevşehir and Kayseri environs are the most continental parts of the Cappadocia with a high inter-annual variability and low temperatures. Cappadocia is characterized with a continental rainfall regime having a maximum precipitation in spring. Variability of summer precipitation totals is greater than that of other seasons, varying from 65.7% to 78%. The CVs of the annual precipitation totals are about 18% at north and about 20% at south. Semi-arid and dry sub-humid or semi-humid climate types prevail over Cappadocia according to Thornthwaite’s moisture and Erinç’s aridity indices. Steppe is the dominant vegetation formation with sparse dry forests. The Cappadocia is vulnerable to the desertification processes due to both natural factors (e.g. degree of aridity, climate-process system, weathering of tuffs, erosion, climate change, etc. and human-involvement (e.g. land degradation and intensive tourism, etc.. In order to mitigate desertification and to preserve the historical and cultural heritages in Cappadocia, sustainable land-use management and tourism planning applications are urgently needed.

  12. Ecological opportunity and the evolution of habitat preferences in an arid-zone bird: implications for speciation in a climate-modified landscape.

    Science.gov (United States)

    Norman, Janette A; Christidis, Les

    2016-01-01

    Bioclimatic models are widely used to investigate the impacts of climate change on species distributions. Range shifts are expected to occur as species track their current climate niche yet the potential for exploitation of new ecological opportunities that may arise as ecosystems and communities remodel is rarely considered. Here we show that grasswrens of the Amytornis textilis-modestus complex responded to new ecological opportunities in Australia's arid biome through shifts in habitat preference following the development of chenopod shrublands during the late Plio-Pleistocene. We find evidence of spatially explicit responses to climatically driven landscape changes including changes in niche width and patterns of population growth. Conservation of structural and functional aspects of the ancestral niche appear to have facilitated recent habitat shifts, while demographic responses to late Pleistocene climate change provide evidence for the greater resilience of populations inhabiting the recently evolved chenopod shrubland communities. Similar responses could occur under future climate change in species exposed to novel ecological conditions, or those already occupying spatially heterogeneous landscapes. Mechanistic models that consider structural and functional aspects of the niche along with regional hydro-dynamics may be better predictors of future climate responses in Australia's arid biome than bioclimatic models alone. PMID:26787111

  13. Surficial weathering of iron sulfide mine tailings under semi-arid climate

    Science.gov (United States)

    Hayes, Sarah M.; Root, Robert A.; Perdrial, Nicolas; Maier, Raina; Chorover, Jon

    2014-01-01

    Mine wastes introduce anthropogenic weathering profiles to the critical zone that often remain unvegetated for decades after mining cessation. As such, they are vulnerable to wind and water dispersion of particulate matter to adjacent ecosystems and residential communities. In sulfide-rich ore tailings, propagation to depth of the oxidative weathering front controls the depth-variation in speciation of major and trace elements. Despite the prevalence of surficial mine waste deposits in arid regions of the globe, few prior studies have been conducted to resolve the near-surface profile of sulfide ore tailings weathered under semi-arid climate. We investigated relations between gossan oxidative reaction-front propagation and the molecular speciation of iron and sulfur in tailings subjected to weathering under semi-arid climate at an EPA Superfund Site in semi-arid central Arizona (USA). Here we report a multi-method data set combining wet chemical and synchrotron-based X-ray diffraction (XRD) and X-ray absorption near-edge spectroscopy (XANES) methods to resolve the tight coupling of iron (Fe) and sulfur (S) geochemical changes in the top 2 m of tailings. Despite nearly invariant Fe and S concentration with depth (130–140 and 100–120 g kg−1, respectively), a sharp redox gradient and distinct morphological change was observed within the top 0.5 m, associated with a progressive oxidative alteration of ferrous sulfides to (oxyhydr)oxides and (hydroxy)sulfates. Transformation is nearly complete in surficial samples. Trends in molecular-scale alteration were co-located with a decrease in pH from 7.3 to 2.3, and shifts in Fe and S lability as measured via chemical extraction. Initial weathering products, ferrihydrite and gypsum, transform to schwertmannite, then jarosite-group minerals with an accompanying decrease in pH. Interestingly, thermodynamically stable phases such as goethite and hematite were not detected in any samples, but ferrihydrite was observed even

  14. Weed harrowing in winter cereal under semi-arid conditions

    Energy Technology Data Exchange (ETDEWEB)

    Pardo, G.; Cirujeda, A.; Aibar, J.; Cavero, J.; Zaragoza, C.

    2008-07-01

    Five field experiments on barley and wheat have been carried out in North-Eastern Spain on the same field during the cropping seasons 1999-00 to 2003-04 to compare the effect of different harrowing adjustments on weed control, weed biomass and cereal yield. The variables considered were harrowing timing (pre- or early post-emergence), one or two passes, travelling direction, harrowing depth and speed compared with an untreated control and herbicide. Excepting year 2001, with very little weed emergence, mechanical control as a whole caused a significant weed plant reduction compared to the untreated plots in all years. No influence of harrowing depth and travelling speed and of pre-emergence harrowing were found in the trials. A single harrowing treatment conducted across the sowing direction gave the same or less control compared to harrowing along the sowing direction. Two harrowing passes achieved a higher efficacy than one single pass and little differences were detected if the second pass was conducted the same day, across the sowing direction or 15 days later. Despite herbicide had generally a higher efficacy than the harrowing treatments, in three out of five years it was found a mechanical control with the same control than herbicide. The effect of the different treatments on weed biomass was lower than on weed number and no significant differences were found for grain yield. Considering that an herbicide treatment in the present conditions is three times more expensive than harrowing, a single post-emergence harrowing can be considered a valid option for low and medium-infested cereal fields. (Author) 30 refs.

  15. Evaporative Cooler Use Influences Temporal Indoor Relative Humidity but Not Dust Mite Allergen Levels in Homes in a Semi-Arid Climate.

    Science.gov (United States)

    Johnston, James D; Tuttle, Steven C; Nelson, Morgan C; Bradshaw, Rebecca K; Hoybjerg, Taylor G; Johnson, Julene B; Kruman, Bryce A; Orton, Taylor S; Cook, Ryan B; Eggett, Dennis L; Weber, K Scott

    2016-01-01

    Concerns about energy consumption and climate change make residential evaporative coolers a popular alternative to central air conditioning in arid and semi-arid climates. However, evaporative coolers have been shown to significantly increase indoor relative humidity and dust mite allergen levels in some studies, while showing no association in other studies. Improved measurement of temporal fluctuations in indoor relative humidity may help identify factors that promote mite growth in homes in dry climates. Dust samples and continuous indoor relative humidity measurements were collected from homes with central air conditioning and homes with evaporative coolers in Utah. Samples were collected over two seasons, winter/spring (Jan-Apr) and summer (July-Sept), 2014. Dust samples were analyzed for Der p 1 and Der f 1 using a two-site monoclonal antibody-based enzyme-linked immunosorbent assay (ELISA) analysis. Housing characteristics including age of home, occupant density, and age of mattresses, furniture, and carpeting were also measured. Positive Der p 1 or Der f 1 samples were found in 25.0% of the homes and there was no difference in mean allergen levels by type of air conditioning. Indoor relative humidity was significantly higher in homes with evaporative coolers compared to those with central air conditioning during the summer. Homes with evaporative coolers also spent significantly more time during summer above 55.0% and 65.0% relative humidity compared to central air homes, but not above 75.0%. Findings from this study suggest that increased humidity from evaporative coolers may not be sufficient to exceed the critical equilibrium humidity or maintain humidity excursions for sufficient duration in relatively larger single-family homes in semi-arid climates to support mite growth and reproduction. PMID:26808528

  16. Evaporative Cooler Use Influences Temporal Indoor Relative Humidity but Not Dust Mite Allergen Levels in Homes in a Semi-Arid Climate.

    Directory of Open Access Journals (Sweden)

    James D Johnston

    Full Text Available Concerns about energy consumption and climate change make residential evaporative coolers a popular alternative to central air conditioning in arid and semi-arid climates. However, evaporative coolers have been shown to significantly increase indoor relative humidity and dust mite allergen levels in some studies, while showing no association in other studies. Improved measurement of temporal fluctuations in indoor relative humidity may help identify factors that promote mite growth in homes in dry climates. Dust samples and continuous indoor relative humidity measurements were collected from homes with central air conditioning and homes with evaporative coolers in Utah. Samples were collected over two seasons, winter/spring (Jan-Apr and summer (July-Sept, 2014. Dust samples were analyzed for Der p 1 and Der f 1 using a two-site monoclonal antibody-based enzyme-linked immunosorbent assay (ELISA analysis. Housing characteristics including age of home, occupant density, and age of mattresses, furniture, and carpeting were also measured. Positive Der p 1 or Der f 1 samples were found in 25.0% of the homes and there was no difference in mean allergen levels by type of air conditioning. Indoor relative humidity was significantly higher in homes with evaporative coolers compared to those with central air conditioning during the summer. Homes with evaporative coolers also spent significantly more time during summer above 55.0% and 65.0% relative humidity compared to central air homes, but not above 75.0%. Findings from this study suggest that increased humidity from evaporative coolers may not be sufficient to exceed the critical equilibrium humidity or maintain humidity excursions for sufficient duration in relatively larger single-family homes in semi-arid climates to support mite growth and reproduction.

  17. Nursery pre-conditioning of plants for revegetation, gardening and landscaping in semi-arid environments

    OpenAIRE

    Franco Leemhuis, José Antonio; Martínez Sánchez, Juan José; Fernández Hernández, Juan Antonio; Bañón Arias, Sebastián del Pilar; Ochoa Rego, Jesús; Vicente Colomer, María José

    2010-01-01

    In landscaping and xerogardening projects, under semi-arid conditions, appropriate techniques used in the nursery during seedling production are crucial for the establishment, survival and subsequent growth of plants after transplanting (Figure 1). Morphological and anatomical adaptations in seedlings include reductions in shoot height and/or leaf area, rises in root-collar diameter and root growth potential and, often, a reduction in the shoot:root ratio; in addition, there are physiological...

  18. Geochemical Processes Controlling the Generation and Environmental Impacts of Acid Mine Drainage in Semi Arid Conditions

    OpenAIRE

    Magombedze, Chris

    2006-01-01

    This study evaluates the geochemical processes that control the geochemistry of acid mine drainage in semi arid conditions. The central objective is to characterise and understand the evolution of acid mine drainage and its potential environmental impacts on the Mazowe River sub-catchment, in north east Zimbabwe. The work is based on a case study at three neighbouring metal sulphide mines, namely Trojan Nickel Mine, Mazowe Gold Mine and Iron Duke Pyrites.The methodology used in this research ...

  19. Evaluation of oxidative stress during adverse environmental conditions in Marwari sheep from arid tracts in India

    OpenAIRE

    Ruchi Maan; Nalini Kataria,

    2012-01-01

    The purpose of the study was to evaluate oxidative stress during adverse environmentalconditions in Marwari sheep breed, to monitor the health status. Six hundred and thirty animals weresampled belonging to arid tracts of Rajasthan, India during adverse environmental conditions includingextreme hot and extreme cold. Oxidative stress was evaluated by determining serum catalase activitiesby basic colorimetric method in which serum was reacted with hydrogen peroxide for specific period oftime. T...

  20. Comparative characteristics of anatomical and morphological adaptations of plants of two subgenera Haworthia Duval to arid environmental conditions

    Directory of Open Access Journals (Sweden)

    Nataliya Volodymyrivna Nuzhyna

    2015-03-01

    Full Text Available This paper presents the comparative anatomical and morphological characteristics of plants of two subgenera: Haworthia and Hexangularis. The study revealed two different strategies of adaptation to arid conditions of the growth of different subgenera of the genus Haworthia. Plants of the subgenus Haworthia adapted to arid conditions by increasing the accumulation of water, the presence of “windows”, a smaller stoma size, and a thinner outer wall of the epidermis cells. On the other hand, plants of the subgenus Hexangularis adapted to arid conditions by reducing overheating and transpiration as well as by the presence of papillae and a thickened outer wall of the epidermis cells.

  1. Climatic and Grazing Controls on Biological Soil Crust Nitrogen Fixation in Semi-arid Ecosystems

    Science.gov (United States)

    Schwabedissen, S. G.; Reed, S.; Lohse, K. A.; Magnuson, T. S.

    2014-12-01

    Nitrogen, next to water, is believed to be the main limiting resource in arid and semi-arid ecosystems. Biological soil crusts (biocrusts) -a surface community of mosses, lichens and cyanobacteria-have been found to be the main influx of "new" nitrogen (N) into many dryland ecosystems. Controls on biocrust N fixation rates include climate (temperature and moisture), phosphorus availability, and disturbance factors such as trampling, yet a systematic examination of climatic and disturbance controls on biocrusts communities is lacking. Biocrust samples were collected along an elevation gradient in the Reynolds Creek Experimental Watershed near Murphy, Idaho. Four sites were selected from a sagebrush steppe ecosystem with precipitation ranging from ≤250mm/yr to ≥1100mm/yr. Each site included 5 grazed plots and one historic exclosure plot that has been free from grazing for more than 40 years. Five samples each were collected from under plants and from interplant spaces from the grazed plots and exclosures and analyzed for potential N fixation using an acetylene reduction assay. We hypothesized that N fixation rates would be the highest in the exclosures of the two middle sites along the elevation gradient, due to the lack of disturbance and optimal temperature and moisture, respectively. As predicted, results showed higher rates of potential N fixation in exclosures than non-exclosures at a mid-elevation 8.4 ± 3.1 kg N/ha/yr in the exclosures compared to 1.8 ± 1.5 kg N/ha/yr indicating that grazing may reduce N fixation activity. Interestingly, rates were 2-5 times lower under plant canopies compared to interplant spaces at all but the highest elevation site. Findings from our study suggest that biocrust N fixation may be a dominant input of N into theses dryland systems and, in line with our hypotheses, that climate, location within the landscape, and disturbance may interact to regulate the rates of this fundamental ecosystem process.

  2. Ocean climate and seal condition

    Directory of Open Access Journals (Sweden)

    Crocker Daniel E

    2005-03-01

    Full Text Available Abstract Background The condition of many marine mammals varies with fluctuations in productivity and food supply in the ocean basin where they forage. Prey is impacted by physical environmental variables such as cyclic warming trends. The weaning weight of northern elephant seal pups, Mirounga angustirostris, being closely linked to maternal condition, indirectly reflects prey availability and foraging success of pregnant females in deep waters of the northeastern Pacific. The aim of this study was to examine the effect of ocean climate on foraging success in this deep-diving marine mammal over the course of three decades, using cohort weaning weight as the principal metric of successful resource accrual. Results The mean annual weaning weight of pups declined from 1975 to the late 1990s, a period characterized by a large-scale, basin-wide warm decadal regime that included multiple strong or long-duration El Niños; and increased with a return to a cool decadal regime from about 1999 to 2004. Increased foraging effort and decreased mass gain of adult females, indicative of reduced foraging success and nutritional stress, were associated with high ocean temperatures. Conclusion Despite ranging widely and foraging deeply in cold waters beyond coastal thermoclines in the northeastern Pacific, elephant seals are impacted significantly by ocean thermal dynamics. Ocean warming redistributes prey decreasing foraging success of females, which in turn leads to lower weaning mass of pups. Annual fluctuations in weaning mass, in turn, reflect the foraging success of females during the year prior to giving birth and signals changes in ocean temperature cycles.

  3. Degradation of High Voltage Polymeric Insulators in Arid Desert's Simulated Environmental Conditions

    Directory of Open Access Journals (Sweden)

    Yasin Khan

    2009-01-01

    Full Text Available Problem statement: High Voltage (HV polymeric insulators are replacing ceramic insulator commonly used for HV outdoor networks due to their ease of handling, reliability and cost. However, their long term performance and reliability are major concerns to power utilities. Approach: To investigate their performance in arid desert's conditions, two types of HV composite insulators were aged as per International Electrochemical Commission (IEC standard-61109. Additional test samples were subjected to accelerated aging conditions simulating the actual Ultraviolet (UV radiation intensity and temperature in the inland desert. Results: This study described the experimental results of the effects of thermo electric stress and UV radiations on the polymeric insulators aged under two conditions i.e., as per IEC standard and modified IEC standard that simulates the inland arid desert. The tests results after the artificial accelerated aging indicated that the dielectric response of thermoplastic insulators under the tested thermo-electric cum UV-irradiations outperforms Silicone rubber insulators.Conclusion: From the obtained results it will be easy to assess the performance and suitability of composite insulators for their applications in arid desert environments.

  4. Statistical downscaling of climate data to estimate streamflow in a semi-arid catchment

    Directory of Open Access Journals (Sweden)

    S. Samadi

    2012-04-01

    Full Text Available Linear and non-linear statistical 'downscaling' study is done to relate large-scale climate information from a general circulation model (GCM to local-scale river flows in west Iran. This study aims to investigate and evaluate the more promising downscaling techniques, and provides a through inter comparison study using the Karkheh catchment as an experimental site in a semi arid region for the years of 2040 to 2069. A hybrid conceptual hydrological model was used in conjunction with modeled outcomes from a General Circulation Model (GCM, HadCM3, along with two downscaling techniques, Statistical Downscaling Model (SDSM and Artificial Neural Network (ANN, to determine how future streamflow may change in a semi arid catchment. The results show that the choice of a downscaling algorithm having a significant impact on the streamflow estimations for a semi-arid catchment, which are mainly, influenced, respectively, by atmospheric precipitation and temperature projections. According to the SDSM and ANN projections, daily temperature will increase up to +0.58° (+3.90% and +0.48° (+3.48% and daily precipitation will decrease up to −0.1mm (−2.56% and −0.4 mm (−2.82% respectively. Moreover streamflow changes corresponding to downscaled future projections presented a reduction in mean annual flow of −3.7 m3 s−1 and −9.47 m3 s−1 using SDSM and ANN outputs respectively. The results suggest a significant decrease of streamflow in both downscaling projections, particularly in winter. The discussion considers the performance of each statistical method for downscaling future flow at catchment scale as well as the relationship between atmospheric processes and flow variability and changes.

  5. Climatic and Hydrological Changes of Past 100 Years in Asian Arid Zone

    Science.gov (United States)

    Feng, Zhaodong; Salnikov, Vitaliy; Xu, Changchun

    2014-05-01

    The Asian Arid Zone (AAZ) is here defined to include the following regions: northwestern China, Mongolia, Kazakhstan, Kyrgyzstan, Tajikistan, Turkmenistan, and Uzbekistan. Generally speaking, the AAZ has experienced a temperature rising during the past 100 years that was significantly faster than the global average (0.14 ºC per decade). Specifically, the rate was 0.39 ºC per decade in northwestern China (1950-2010), 0.26 ºC per decade in Kazakhstan (1936-2005), 0.22 ºC per decade in Mongolia (1940-2010), 0.29 ºC per decade in Uzbekistan (1950-2005), 0.18 ºC per decade in Turkmenistan (1961-1995). It should be noted that the mountainous parts of AAZ seems to have experienced a slower rate of temperature rising. For example, the rate was 0.10 ºC per decade in Tajikistan (1940-2005) and was 0.08 ºC per decade in Kyrgyzstan (1890-2005). Precipitation has a slight increasing trend in northwestern China, but it has fluctuated along a near-constant line in the rest of the AAZ. Hydrological data from high-elevation basin show that the runoff has been increasing primarily as a result of rising temperature that caused increases in ice melting. A natural decreasing trend of surface runoff in low-elevation basins is undeniable and the decreasing trend is attributable to intensified evaporation under warming conditions. It is true that the total amount of runoff in the Tianshan Mountains and the associated basins has been increased primarily as a result of temperature rising-resulted increases in ice melting. But, approaching to the turning point of glacier-melting supplies to runoff will pose a great threat to socio-economic sustainability and to ecological security. The turning point refers to the transition from increasing runoff to decreasing runoff within ice melting supplied watersheds under a warming climate.

  6. NDVI-based vegetation responses to climate change in an arid area of China

    Science.gov (United States)

    Xu, Yufeng; Yang, Jing; Chen, Yaning

    2015-07-01

    Warming of the climate system is unequivocal, and the change of climate variables will eventually have a great impact on vegetation cover and agricultural practices, especially in the arid area Xinjiang in China, whose agriculture and ecosystems are heavily vulnerable to climate change. In this paper, normalized difference vegetation index (NDVI) was used to study the vegetation growth and its response to climate change in Xinjiang. Firstly, two NDVI datasets (Global Inventory Modeling and Mapping Studies (GIMMS) and Moderate Resolution Imaging Spectroradiometer (MODIS)) were merged through a pixel-wise regression analysis to obtain a long time series of NDVI data, and then, relationships between yearly NDVI and yearly climate variables, and monthly NDVI and monthly climate variables were extensively investigated for grassland and cropland in northern and southern Xinjiang, respectively. Results show the following: (1) there was an increasing trend in NDVI for both grassland and cropland in both northern and southern Xinjiang over the past decades and trends were significant except that for grassland in northern Xinjiang; (2) precipitation and evaporation were more important than temperature for grassland in northern Xinjiang, while precipitation and temperature were more important than evaporation for grassland in southern Xinjiang and cropland in both northern and southern Xinjiang; (3) NDVI was highly correlated with accumulated monthly precipitation instead of monthly precipitation, and there was a lagged effect of precipitation, temperature, and evaporation on NDVI change. However, lagged effects were only significant in specific months. The results could be helpful to agricultural practices; e.g., based on lagged effect of precipitation, irrigation in July is very important for crop growth.

  7. Effects of changing climate on aquatic habitat and connectivity for remnant populations of a wide-ranging frog species in an arid landscape.

    Science.gov (United States)

    Pilliod, David S; Arkle, Robert S; Robertson, Jeanne M; Murphy, Melanie A; Funk, W Chris

    2015-09-01

    Amphibian species persisting in isolated streams and wetlands in desert environments can be susceptible to low connectivity, genetic isolation, and climate changes. We evaluated the past (1900-1930), recent (1981-2010), and future (2071-2100) climate suitability of the arid Great Basin (USA) for the Columbia spotted frog (Rana luteiventris) and assessed whether changes in surface water may affect connectivity for remaining populations. We developed a predictive model of current climate suitability and used it to predict the historic and future distribution of suitable climates. We then modeled changes in surface water availability at each time period. Finally, we quantified connectivity among existing populations on the basis of hydrology and correlated it with interpopulation genetic distance. We found that the area of the Great Basin with suitable climate conditions has declined by approximately 49% over the last century and will likely continue to decline under future climate scenarios. Climate conditions at currently occupied locations have been relatively stable over the last century, which may explain persistence at these sites. However, future climates at these currently occupied locations are predicted to become warmer throughout the year and drier during the frog's activity period (May - September). Fall and winter precipitation may increase, but as rain instead of snow. Earlier runoff and lower summer base flows may reduce connectivity between neighboring populations, which is already limited. Many of these changes could have negative effects on remaining populations over the next 50-80 years, but milder winters, longer growing seasons, and wetter falls might positively affect survival and dispersal. Collectively, however, seasonal shifts in temperature, precipitation, and stream flow patterns could reduce habitat suitability and connectivity for frogs and possibly other aquatic species inhabiting streams in this arid region. PMID:26445654

  8. Impacts of anthropogenic activities on climate change in arid and semiarid areas based on CMIP5 models

    Science.gov (United States)

    Zhao, T.; LI, C.

    2014-12-01

    Based on all (ALL) forcing and single-forcing runs from CMIP5 (Coupled Model Intercomparison Project Phase 5) simulations, the present paper examines the anthropogenic influence of greenhouse gases (GHG), anthropogenic aerosols (AA), land use (LU) and combined anthropogenic (Ant) effects on climate change in global arid and semiarid regions. Significant warming is a robust feature over the global land as a response to Ant and GHG forcings, and the warming rate from the latter forcing is two to three times that of ALL forcing results over the past 60 years. AA produces remarkable cooling over the global land surface, whereas LU leads to slight cooling in most arid and semiarid areas. GHG- and Ant-driven increases of precipitation are found in most land areas, especially in arid and semiarid regions. AA and LU produce substantial variation of precipitation over various areas, and current uncertainties are relatively great in AA and LU forcing runs. Ensemble Empirical Mode Decomposition (EEMD) is used to analyze temporal scales of annual temperature and precipitation. The results show that interdecadal and multidecadal variations of temperature and precipitation are attributable to combined natural and anthropogenic forcings in most arid and semiarid regions, where AA dominates variations of both temperature and precipitation on multidecadal timescales. Both GHG and LU have positive effects on multidecadal changes of precipitation over arid and semiarid regions globally. However, the latter significantly prevents multidecadal changes of temperature over arid and semiarid regions of Australia.

  9. Developing User-Driven Climate Information Services to Build Resilience Amongst Groups at Risk of Drought and Flood in Arid and Semi-Arid Land Counties in Kenya

    Science.gov (United States)

    Githungo, W. N.; Shaka, A.; Kniveton, D.; Muithya, L.; Powell, R.; Visman, E. L.

    2014-12-01

    The Arid and Semi-Arid Land (ASAL) counties of Kitui and Makueni in Kenya are experiencing increasing climate variability in seasonal rainfall, including changes in the onset, cessation and distribution of the two principal rains upon which the majority of the population's small-holder farmers and livestock keepers depend. Food insecurity is prevalent with significant numbers also affected by flooding during periods of intense rainfall. As part of a multi-partner Adaptation Consortium, Kenya Meteorological Services (KMS) are developing Climate Information Services (CIS) which can better support decision making amongst the counties' principal livelihoods groups and across County Government ministries. Building on earlier pilots and stakeholder discussion, the system combines the production of climate information tailored for transmission via regional and local radio stations with the establishment of a new SMS service. SMS are provided through a network of CIS intermediaries drawn from across key government ministries, religious networks, non-governmental and community groups, aiming to achieve one SMS recipient per 3-500 people. It also introduces a demand-led, premium-rate SMS weather information service which is designed to be self-financing in the long term. Supporting the ongoing process of devolution, KMS is downscaling national forecasts for each county, and providing seasonal, monthly, weekly and daily forecasts, as well as warnings of weather-related hazards. Through collaboration with relevant ministries, government bodies and research institutions, including livestock, agriculture, drought management and health, technical advisories are developed to provide guidance on application of the climate information. The system seeks to provide timely, relevant information which can enable people to use weather and climate information to support decisions which protect life and property and build resilience to ongoing climate variability and future change.

  10. Establishment of a planted field with Mediterranean shrubs in Sardinia and its evaluation for climate mitigation and to combat desertification in semi-arid regions

    Directory of Open Access Journals (Sweden)

    De Dato GD

    2009-06-01

    Full Text Available Forested areas are important in arid and semi-arid regions primarily to combat desertification, but also to increase carbon sinks. To reverse the land degradation processes, restoration in the Mediterranean Basin had been frequently obtained by planting indigenous and exotic conifers, but it has been demonstrated that shrubs are nurse species for tree seedlings. Furthermore, planting indigenous shrubs is more efficient than allochthonous in restoring degraded soils. The aims of this work were: 1 to illustrate an experimental area in Sardinia used as a test-site to build up afforestation and reforestation activities in arid and semi-arid areas with autochthonous shrub species; 2 to show the results on plant survival and biomass one year after plantation trying to explain the role of different densities and specific compositions; 3 to hypothesize some trends of C accumulation of this “artificial” Mediterranean semi-arid shrubland by comparison with data found in the literature. The area is located in North West Sardinia, and is characterized by a Mediterranean climate. The revegetation was set up in February 2006, planting local species (Juniperus phoenicea, Pistacia lentiscus and Rosmarinus officinalis. Three densities and three specific compositions (monospecific plots with P. lentiscus, monospecific plots with J. phoenicea and mixed plots with the three cited species were combined. One month after plantation, almost all plants were alive, but mortality increased after summer, independently of the treatments, likely due to summer drought. During the first year, no differences among the densities and the specific compositions were observed. Total above-ground biomass was in the range of 0.8-3.0 g m-2. Below-ground biomass was in the range of 0.9-1.7 g m-2. A significant lower biomass was measured in October, especially in the Pistacia plots. Higher densities and plant mixing seemed to better perform, allowing establishment of species with a

  11. Climatic Conditions, Cultural Diversity, and Labor Productivity

    OpenAIRE

    Gundlach, Erich; Matus-Velasco, Ximena

    2000-01-01

    Countries with the highest labor productivity overwhelmingly lie in the world's temperate climatic zones far away from the equator. The question we address is whether climatic conditions as measured by distance from the equator remain correlated with labor productivity after other variables are taken into account. We find that climatic conditions do not have a significant impact on labor productivity once we control for factor accumulation and cultural diversity within countries. Our regressi...

  12. Improving Modeling of the Summer Climate of Semi-Arid Regions

    Science.gov (United States)

    Eltahir, E.; Marcella, M.

    2009-04-01

    Presented is a study on the importance of certain land surface processes in accurately simulating the summertime climate of Southwest Asia. A nearly 4 degree C bias is simulated in summertime temperatures, by standard Regional Climate Model version 3 (RegCM3). Biases are also found in surface albedo, shortwave incident, and surface vapor pressure. Using satellite data, (Earth Radiation Budget Experiment-ERBE) modifications are introduced to match simulated surface albedo to the ERBE data. In addition, by incorporating RegCM3's dust module with sub-grid variability, surface shortwave incident biases are reduced. Lastly, representing the irrigation and marshlands of Mesopotamia reduces vapor pressure deficits in the region. All of these factors combined, along with errors in observational datasets, account for the 4 degree C warm bias in RegCM3 simulations. We conclude that accurate representations of albedo, irrigation, and dust emissions are important processes to be included for accurate summertime climate modeling in semi-arid regions around the world.

  13. Interaction between groundwater and trees in an arid site: Potential impacts of climate variation and groundwater abstraction on trees

    Science.gov (United States)

    Yin, Lihe; Zhou, Yangxiao; Huang, Jinting; Wenninger, Jochen; Zhang, Eryong; Hou, Guangcai; Dong, Jiaqiu

    2015-09-01

    The understanding of the interaction between groundwater and trees is vital for sustainable groundwater use and maintenance of a healthy ecosystem in arid regions. The short- and long-term groundwater contribution to tree water use was investigated using the HYDRUS-1D model and stable isotopes. For the short-term simulation, the ratio between the actual transpiration (Ta) and potential transpiration (Tp) approached almost ∼1.0 due to the constant groundwater uptake. The results from the short-term simulation indicated that the groundwater contribution to tree water use ranged between 53% and 56% in the dry season (May-June) and 16-19% in the wet period (August-September). Isotopic analysis indicated that groundwater contributed to 45% of plant water use in the dry season, decreasing to 4-12% during the wet period. Because of canopy interception and transpiration, groundwater recharge only occurred after heavy rainfall and accounted for 3-8% of the total heavy rainfall. For the long-term simulation, Ta/Tp ranged between 0.91 and 1.00 except in 2007 (0.78), when the water table declined because of groundwater abstraction. In the scenario simulation for deep water table conditions caused by anthropogenic activities, Ta/Tp ranged between 0.09 and 0.40 (mean = 0.22) that is significantly lower than the values in the natural conditions. In conclusion, vegetation restoration in arid zones should be cautious as over-planting of trees will decrease the groundwater recharge and potentially cause a rapid drop in water table levels, which in turn may result in the death of planted trees. Trees adapt to arid regions by adopting root patterns that allow soil water uptake by shallow roots and groundwater use by deep roots, thus climatic variation itself may not bring severe negative impact on trees. However, anthropogenic activities, such as groundwater abstraction, will result in significant water table decline that will reduce actual transpiration of trees significantly

  14. Interacting Effects of Land Management Strategies and Climate Change on the Ecohydrologic Systems of the Semi-Arid Santa Fe Municipal Watershed

    Science.gov (United States)

    Dugger, A. L.; Tague, C.; Allen, C. D.; Ringler, T.

    2009-12-01

    Current regional climate models predict overall warming in the Southwest U.S. along with increased drying and potential shifts in the timing and intensity of precipitation events. While climate controls on the water budget through precipitation inputs and the timing of snow accumulation and melt are critical in semi-arid mountain watersheds, we also expect vegetation water use and productivity changes to exert a strong control on the distribution, timing, and quantity of water availability. Given that management practices can significantly alter the structure and density of vegetation, land management has the potential to either mitigate or exacerbate certain climate change impacts on the water system. Our main goal is to examine climate, subsurface, and vegetation interactions in the semi-arid Santa Fe Municipal Watershed to determine the dominant controls on streamflow as well as the envelope of expected hydrologic behavior under potential climate and land management changes. We use a process-based, spatially distributed, integrated hydro-ecological model (RHESSys) to simulate water and vegetation carbon cycling. Specifically, we build a physically-based model calibrated for soil and effective drainage parameters and apply a range of climate inputs based on historical variability and forced with extremes in projected climate shifts. We then investigate the spatially and seasonally variable responses of vegetation, the timing and amounts of streamflow, and the interactions between these processes under different land management and disturbance schemes. This modeling exercise produces a series of probability distributions for annual and seasonal streamflow yields under various conditions, which under a statistical lens reveals the dominant controls on the magnitude and timing of streamflow. Results from this analysis highlight confounding (or mitigating) impacts on the vulnerability of water yields to climate change.

  15. Impact of Direct Soil Moisture and Revised Soil Moisture Index Methods on Hydrologic Predictions in an Arid Climate

    Directory of Open Access Journals (Sweden)

    Milad Jajarmizadeh

    2014-01-01

    Full Text Available The soil and water assessment tool (SWAT is a physically based model that is used extensively to simulate hydrologic processes in a wide range of climates around the world. SWAT uses spatial hydrometeorological data to simulate runoff through the computation of a retention curve number. The objective of the present study was to compare the performance of two approaches used for the calculation of curve numbers in SWAT, that is, the Revised Soil Moisture Index (SMI, which is based on previous meteorological conditions, and the Soil Moisture Condition II (SMCII, which is based on soil features for the prediction of flow. The results showed that the sensitive parameters for the SMI method are land-use and land-cover features. However, for the SMCII method, the soil and the channel are the sensitive parameters. The performances of the SMI and SMCII methods were analyzed using various indices. We concluded that the fair performance of the SMI method in an arid region may be due to the inherent characteristics of the method since it relies mostly on previous meteorological conditions and does not account for the soil features of the catchment.

  16. Effects of changes in land use and management on landslide processes induced by water under semi-arid Mediterranean and humid tropical conditions

    Science.gov (United States)

    Pla-Sentís, I.

    2012-04-01

    Under particular climate conditions, the hydrological processes in sloping lands leading to landslides induced by water are affected both by the soil properties and by the use and management of the land. Frequently, the influence of changes in use and management of the land is even more important than the changes in climate, associated or not to global changes, in increasing the risks or triggering landslides. In this contribution there are presented two cases of landslides triggered by hydrological changes induced by changes in land use and management, under semi-arid mediterranean climate conditions (terracing of dry land vineyards in NE Spain) and under humid tropical climate conditions (deforestation and change to overgrazed grassland in W Venezuela). There are shown the induced soil and land hydrological changes in each case, both evaluated in situ under field conditions and using the simulation model SOMORE developed by the author. This model, based on hydrological processes evaluated in situ, has been successfully used for predicting the changes in soil water regime and soil water balance, and to deduce their effects on problems related with water supply to plants, runoff, surface erosion, mass erosion (landslides), and flooding, under different climate and land use and management. From that we may be able both to predict the probabilities and risks of landslides under the present and previewed changing climatic conditions, and to select and apply the best land use and management practices to prevent them. The structure of this non empirical hydrological model is also presented.

  17. Vegetation and climate history in arid western China during MIS2: New insights from pollen and grain-size data of the Balikun Lake, eastern Tien Shan

    Science.gov (United States)

    Zhao, Yongtao; An, Cheng-Bang; Mao, Limi; Zhao, Jiaju; Tang, Lingyu; Zhou, Aifeng; Li, Hu; Dong, Weimiao; Duan, Futao; Chen, Fahu

    2015-10-01

    Marine Isotope Stage (MIS) 2 is mostly a cold period encompassing the Last Glacial Maximum (LGM), but the regional expression of MIS2 in arid areas of China is not well known. In this paper, we use high-resolution lacustrine pollen and grain-size records from Balikun Lake to infer vegetation, lake evolution, and climate in arid western China during MIS2. Our results suggest that: 1) the regional vegetation around Balikun was mainly dominated by desert and/or desert-steppe, and Balikun Lake was relatively shallow and experienced high aeolian input during MIS2; 2) distinctive runoff from mountain glacial meltwater in the eastern parts of the Balikun basin caused a high relative abundance of Artemisia pollen during the LGM (26.5-19.2 cal kyr BP), while simultaneously the desert areas expanded as indicated by the high abundance of desert shrubs (e.g., Elaeagnaceae, Rhamnaceae, Hippophae). This cold and dry LGM climate triggered a substantial lowering of lake level; 3) an extremely cold and dry climate prevailing from 17.0 to 15.2 cal kyr BP, correlated with Heinrich event 1 (H1), would explain the low vegetation cover found then; and 4) the warm and humid Bølling/Allerød interstadial (BA: ca. 15-ca. 13 cal kyr BP) is clearly recorded in the Balikun region by the development of wetland herb communities (e.g., Poaceae, Cyperaceae, Typha), and the lake level rose due to increased runoff. Our results challenge the traditional view of cold and wet climatic conditions and high lake levels in arid western China during the LGM, and we propose that changes in local temperature modulated by July insolation was an indispensable factor in triggering vegetation evolution in the Balikun region during MIS2.

  18. [Changes of China agricultural climate resources under the background of climate change. VII. Change characteristics of agricultural climate resources in arid and semi-arid region of Tibet Plateau].

    Science.gov (United States)

    Xu, Hua-jun; Yang, Xiao-guang; Wang, Wen-feng; Xu, Chao

    2011-07-01

    Based on the 1961-2007 ground observation data from 55 meteorological stations in arid and semi-arid region of Tibetan Plateau, and by using 5-day moving average method and ArcGIS-IDW module, this paper analyzed the spatiotemporal change characteristics and climatic trend rates of agricultural climate resources in the region in 1961-1980 (period I) and 1981-2007 (period II). In 1961-2007, the sunshine duration during the growth season of chimonophilous crops in the study region changed less, while that during the growth season of thermophilic crops increased but with little spatial change. Comparing with those in period I, the average value of accumulated temperature in period II showed an increasing trend, and the area with > or = 1500 degrees C x d during the growth season of thermophilic crops increased by 33.9%. The precipitation decreased gradually from southeast to northwest. During the growth season of chimonophilous crops, the precipitation in the southeast in the two periods reached 800 mm, but the climatic trend in other areas was positive or negative, and the change rate was small. The area with precipitation > or = 400 mm during the growth season of thermophilic crops in period II expanded by 40%, as compared in period I. The reference crop evapotranspiration (ET0) generally increased slightly, and shared the similar spatial distribution pattern with sunshine duration and accumulated temperature. During the growth season of thermophilic crops, the area with ET0 > or = 400 mm in period II expanded by 35.7%, compared with that in period I. In the study period, the heat and precipitation resources during crop growth seasons in Tibet Plateau increased in a certain degree, which was very beneficial to the agriculture-stock production. However, the increase of reference crop evapotranspitation indicated the increase of potential evaporation. Thereby, the researches about the possible effects of climate change on agriculture-stock production should be further

  19. Climate Conditioning for the Learning Environment.

    Science.gov (United States)

    Perkins and Will, Architects, Chicago, IL.

    Discusses heating, cooling, and ventilation for the classroom in relationship to students' learning abilities. It is designed to assist school boards, administrators, architects and engineers in understanding the beneficial effects of total climate control, and in evaluating the climate conditioning systems available for schools. Discussion…

  20. Modeling Spatial Recharge in the Arid Southern Okanagan Basin and Impacts of Future Predicted Climate Change

    Science.gov (United States)

    Allen, D. M.; Toews, M. W.

    2007-12-01

    Groundwater systems in arid regions will be particularly sensitive to climate change owing to the strong dependence of evapotranspiration rates on temperature, and potential shifts in the precipitation amounts and timing. In this study, future predicted climate change from three GCMs (CGCM1 GHG+A, CGCM3.1 A2, and HadCM3 A2) are used to evaluate the sensitivity of recharge in the Oliver region of the Okanagan Valley, south- central British Columbia, where annual precipitation is approximately 300~mm. Temperature data were downscaled using Statistical Downscaling Model (SDSM), while precipitation and solar radiation changes were estimated directly from the GCM data. Results for the region suggest that temperature will increase up to 4°C by the end of the century. Precipitation is expected to decrease in the spring, and increase in the fall. Solar radiation may decrease in the late summer. Shifts in climate, from present to future-predicted, were applied to the LARS-WG stochastic weather generator to generate daily stochastic weather series. Recharge was modeled spatially using output from the HELP hydrologic model applied to one-dimensional soil columns. An extensive valley-bottom soil database was used to determine both the spatial variation and vertical assemblage of soil horizons in the Oliver region. Soil hydraulic parameters were estimated from soil descriptions using pedotransfer functions through the ROSETTA program. Leaf area index (LAI) was estimated from ground-truthed Landsat 5 TM imagery, and surface slope was estimated from a digital elevation model. Irrigation application rates were modified for each climate scenario based on estimates of seasonal crop water demand. Daily irrigation was added to precipitation in irrigation districts using proportions of crop types along with daily climate and evapotranspiration data from LARS-WG. The two dominant crop classes are orchard (including peaches, cherries and apples) and vineyards (grapes). Recharge in

  1. Wetlands as a Record of Climate Change and Hydrological Response in Arid Rift Settings

    Science.gov (United States)

    Ashley, G. M.

    2004-12-01

    Of all the terrestrial depositional settings, rift basins typically provide the greatest accommodation space, and consequently have some of the longest records of continental sedimentation. Lake deposits were the only rift component studied for records of long-term climatic change and for testing hypotheses of orbital forcing. Recently, the continuing quest for the paleontological and cultural records of human origins entombed in the sedimentary rocks of the East African Rift System raised questions concerning hydrologic and biologic response to climatic change. Additional issues are the impact of climate on paleolandscapes and the environmental stresses that might have affected human evolution. Other important indicators of rift hydrology, such as springs and wetlands are now emerging as viable records of climate change. Rift valley basins are shallow, hydrologically closed systems that are responsive to shifts in climate, and specifically sensitive to changes in the hydrologic budget (P-ET). Long term wet-dry cycles in the low latitudes are thought to be astronomically controlled, i.e. Milankovitch precession cycles (19-23 ka). In the tropics, precipitation (P) varies with changes in solar insolation which fluctuates similarly. Springs and groundwater-fed wetlands are common, however the sources and sustainability of water or what geologic factors lead to the formation and longevity of wetlands is not well established. It appears that rainfall is trapped on topographic highs (rift fault blocks and volcanoes). This meteoric water infiltrates quickly through porous volcanic rocks and is stored in aquifers and released slowly. As a component of the rift hydrologic system, wetlands appear to be reliable indicators of rainfall fluctuations on both Milankovitch and sub-Milankovitch time scales. Wetland sediments are commoner in the geologic record during times of higher rainfall and are less common during drier periods. Modern arid rift wetland records are peats and

  2. Suitability of different comfort indices for the prediction of thermal conditions in tree-covered outdoor spaces in arid cities

    Science.gov (United States)

    Ruiz, María Angélica; Correa, Erica Norma

    2015-10-01

    Outdoor thermal comfort is one of the most influential factors in the habitability of a space. Thermal level is defined not only by climate variables but also by the adaptation of people to the environment. This study presents a comparison between inductive and deductive thermal comfort models, contrasted with subjective reports, in order to identify which of the models can be used to most correctly predict thermal comfort in tree-covered outdoor spaces of the Mendoza Metropolitan Area, an intensely forested and open city located in an arid zone. Interviews and microclimatic measurements were carried out in winter 2010 and in summer 2011. Six widely used indices were selected according to different levels of complexity: the Temperature-Humidity Index (THI), Vinje's Comfort Index (PE), Thermal Sensation Index (TS), the Predicted Mean Vote (PMV), the COMFA model's energy balance (S), and the Physiological Equivalent Temperature (PET). The results show that the predictive models evaluated show percentages of predictive ability lower than 25 %. Despite this low indicator, inductive methods are adequate for obtaining a diagnosis of the degree and frequency in which a space is comfortable or not whereas deductive methods are recommended to influence urban design strategies. In addition, it is necessary to develop local models to evaluate perceived thermal comfort more adequately. This type of tool is very useful in the design and evaluation of the thermal conditions in outdoor spaces, based not only to climatic criteria but also subjective sensations.

  3. Coupled modeling approach to assess climate change impacts on groundwater recharge and adaptation in arid areas

    Science.gov (United States)

    Hashemi, H.; Uvo, C. B.; Berndtsson, R.

    2015-10-01

    The effect of future climate scenarios on surface and groundwater resources was simulated using a modeling approach for an artificial recharge area in arid southern Iran. Future climate data for the periods of 2010-2030 and 2030-2050 were acquired from the Canadian Global Coupled Model (CGCM 3.1) for scenarios A1B, A2, and B1. These scenarios were adapted to the studied region using the delta-change method. A conceptual rainfall-runoff model (Qbox) was used to simulate runoff in a flash flood prone catchment. The model was calibrated and validated for the period 2002-2011 using daily discharge data. The projected climate variables were used to simulate future runoff. The rainfall-runoff model was then coupled to a calibrated groundwater flow and recharge model (MODFLOW) to simulate future recharge and groundwater hydraulic heads. As a result of the rainfall-runoff modeling, under the B1 scenario the number of floods is projected to slightly increase in the area. This in turn calls for proper management, as this is the only source of fresh water supply in the studied region. The results of the groundwater recharge modeling showed no significant difference between present and future recharge for all scenarios. Owing to that, four abstraction and recharge scenarios were assumed to simulate the groundwater level and recharge amount in the studied aquifer. The results showed that the abstraction scenarios have the most substantial effect on the groundwater level and the continuation of current pumping rate would lead to a groundwater decline by 18 m up to 2050.

  4. Effects of environmental conditions on soil salinity and arid region in Tunisia

    Energy Technology Data Exchange (ETDEWEB)

    Ben Ahmed, C.; Ben Rouina, B.; Boukhris, M.

    2009-07-01

    The shortage of water resources of good water quality is becoming an issue in the arid and semi arid regions. for this reason, the use of water resources of marginal quality such as treated wastewater and saline groundwater has become and important consideration, particularly in arid region in Tunisia, where large quantities of saline water are used for irrigation. (Author)

  5. Groundwater Recharge Evaluation in Semi-Arid Northeast Mexico in Response to Projected Climate Change

    Science.gov (United States)

    Wolaver, B. D.

    2007-12-01

    This research evaluates the effects of projected climate change on mountain recharge in the semi-arid Cuatrocinegas Basin (CCB) of northeast Mexico. The CCB UNESCO Biosphere Reserve is located in Coahuila, Mexico (~27° N, ~102° W) and includes > 500 springs that discharge from a regional flow system to wetlands with > 70 endemic species and to an irrigation network. This study tests the hypothesis that projected climate changes will reduce CCB recharge. In CCB, ~75% of annual precipitation (~220 mm at 700 m, ~400 mm at 2350 m) falls between May and October and ~40% falls during the North American Monsoon in June, July, and August. Environmental isotopes indicate aquifer residence times of > 50 years. Stable isotopes (O and H) show that mountain precipitation (at an elevation of ~1170 to 2350 m) dominates groundwater recharge. Recharge is insignificant at lower- elevation valleys that cover the majority of the study area due to high evapotranspiration rates. A Cl--balance water-budget recharge analysis estimates a spatially distributed recharge rate of ~1 to 3% of precipitation to provide at least 35x106 m3/year spring discharge (as measured in canals that drain dozens of springs). IPCC AR4 climate projections predict an annual temperature increase of 3.0 to 3.5°C and an annual precipitation decrease of 5 to 10% for Subregion CNA (located adjacent to CCB) by 2099. During June to August, models project a temperature increase of 3.5 to 4.0°C and a precipitation increase of 0 to 5%. Although global and regional circulation models evaluate mountain regions poorly, a first-order evaluation of climate projections on CCB recharge is needed input to develop effective long-term groundwater management policies. Climate projections suggest that the minimum elevation at which recharge occurs in CCB may increase by ~615 m to 1785 m, which would limit recharge to the highest mountain elevations. If annual precipitation is reduced by 5 to 10% and temperatures increase as

  6. Definitions of climate and climate change under varying external conditions

    Directory of Open Access Journals (Sweden)

    C. Werndl

    2014-06-01

    Full Text Available Commonly, definitions of climate are endorsed where the external conditions are held constant. This paper argues that these definitions risk being empirically void because in reality the external conditions vary. As a consequence, analogous definitions for varying external conditions are explored with help of the recently developed theory of non-autonomous dynamical systems, and the similarities and differences between the cases of constant and varying external conditions are discussed. It is argued that there are analogous definitions for varying external conditions which are preferable to the definitions where the external conditions are held constant. In this context, a novel definition is proposed (namely, climate as the distribution over time under a regime of varying external conditions, which is argued to be promising.

  7. Concept, Design and Performance of a Shape Variable Mashrabiya as a Shading and Daylighting System for Arid Climates

    OpenAIRE

    Karamata, Boris; Andersen, Marilyne

    2014-01-01

    The design of a solar protection system that can minimize solar gains while maximizing daylight and view to the outside is particularly challenging in arid climates, such as in the Middle-East, where sand, wind and corrosion impose specific constraints. We propose a system that provides a trade-off for three requirements: (i) maximize diffuse sunlight and view to the outside, (ii) efficiently block direct sunlight and (iii) transform a fraction of it into diffuse light for indoor daylighting....

  8. Simulation of the Arid Climate of the Southern Great Basin Using a Regional Climate Model.

    Science.gov (United States)

    Giorgi, Filippo; Bates, Gary T.; Nieman, Steven J.

    1992-11-01

    As part of the development effort of a regional climate model (RCM)for the southern Great Basin, this paper present savalidation analysis of the climatology generated by a high-resolution RCM driven by observations. The RCM is aversion of the National Center for atmospheric Research-Pennsylvania State University mesoscale model, version 4 (MM4), modified for application to regional climate simulation. Two multiyear simulations, for the periods 1 January 1982 to 31 December 1983 and 1 January 1988 to 25 April 1989, were performed over the western United States with the RCM driven by European Centre for Medium-Range Weather Forecasts analyses of observations. The model resolution is 60 km. This validation analysis is the first phase of a project to produce simulations of future climate scenarios over a region surrounding Yucca Mountain, Nevada, the only location currently being considered as a potential high-level nuclear-waste repository site.Model-produced surface air temperatures and precipitation were compared with observations from five southern Nevada stations located in the vicinity of Yucca Mountain. The seasonal cycles of temperature and precipitation were simulated well. Monthly and seasonal temperature biases were generally negative and largely explained by differences in elevation between the observing stations and the model topography. The model-simulated precipitation captured the extreme dryness of the Great Basin. Average yearly precipitation was generally within 30% of observed and the range of monthly precipitation amounts was the same as in the observations. Precipitation biases were mostly negative in the summer and positive in the winter. The number of simulated daily precipitation events for various precipitation intervals was within factors of 1.5-3.5 of observed. Overall, the model tended to overestimate the number of light precipitation events and underestimate the number of heavy precipitation events. At Yucca Mountain, simulated

  9. Simulation of the arid climate of the southern great basin using a regional climate model

    International Nuclear Information System (INIS)

    As part of the development effort of a regional climate model (RCM) for the southern Great Basin, this paper presents a validation analysis of the climatology generated by a high-resolution RCM driven by observations. Two multiyear simulations were performed over the western United States with the RCM driven by European Centre for Medium-Range Weather Forecasts analyses of observations. This validation analysis is the first phase of a project to produce simulations of future climate scenarios over a region surrounding Yucca Mountain, Nevada, the only location currently being considered as a potential high-level nuclear-waste repository site. Model-produced surface air temperatures and precipitation were compared with observations from five southern Nevada stations located in the vicinity of Yucca Mountain. The seasonal cycles of temperature and precipitation were simulated well. Monthly and seasonal temperature biases were generally negative and largely explained by differences in elevation between the observing stations and the model topography. The model-simulated precipitation captured the extreme dryness of the Great Basin. Average yearly precipitation biases were mostly negative in the summer and positive in the winter. The number of simulated daily precipitation events for various precipitation intervals was within factors of 1.5-3.5 of observed. Overall, the model tended to overestimate the number of light precipitation events and underestimate the number of heavy precipitation events. At Yucca Mountain, simulated precipitation, soil moisture content, and water infiltration below the root zone (top 1 m) were maximized in the winter. Evaporation peaked in the spring after temperatures began to increase. The conclusion drawn from this validation analysis is that this high-resolution RCM simulates the regional surface climatology of the southern Great Basin reasonably well when driven by meteorological fields derived from observations. 26 refs., 9 figs., 4 tabs

  10. Hydrodynamic caracterisation of an heterogeneous aquifer system under semi-arid climate

    Science.gov (United States)

    Drias, T.; Toubal, A. Ch

    2009-04-01

    The studied zone is a part of the Mellegne's (North-East of Algeria) under pound, this zone is characterised by its semi-arid climate. The water bearing system is formed by the plio-quaternairy alluviums resting on a marley substratuim of age Eocene. The geostatiscitcs approach of the hydrodynamics parameters (Hydrolic load, transmisivity) allowed the study of their spatial distrubution (casting) by the method of Krigeage by blocks and the identification of zones with water-bearing potentialities. In this respect, the zone of Ain Chabro which, is situated in the South of the plain shows the best values of the transmisivity...... The use of a bidimensinnel model in the differences ended in the permanent regime allowed us to establish the global balence sheet (overall assessment) of the tablecloth and to refine the transmisivity field. These would vary more exactley between 10-4 to 10-2 m²/s. The method associating the probability appraoch of Krigeage to that determining the model has facilited the wedging of the model and clarified the inflitration value. Keys words: hydrodynamics, geostatiscitcs, Modeling, Chabro, Tébessa.

  11. A pluvial episode identified in arid Australia during the Medieval Climatic Anomaly

    Science.gov (United States)

    Cohen, T. J.; Nanson, G. C.; Jansen, J. D.; Gliganic, L. A.; May, J.-H.; Larsen, J. R.; Goodwin, I. D.; Browning, S.; Price, D. M.

    2012-11-01

    Optically stimulated luminescence (OSL) ages from a relict shoreline on Lake Callabonna record a major pluvial episode in southern central Australia between 1050 ± 70 and 1100 ± 60 Common Era (CE), within the Medieval Climatic Anomaly (MCA). During this pluvial interval Lake Callabonna filled to 10-12 times the volume of the largest historical filling (1974) and reached maximum depths of 4-5 m, compared to the 0.5-1.0 m achieved today. Until now there has been no direct evidence for the MCA in the arid interior of Australia. A multi-proxy, analogue-based atmospheric circulation reconstruction indicates that the pluvial episode was associated with an anomalous meridional atmospheric circulation pattern over the Southern extratropics, with high sea-level pressure ridges in the central Indian Ocean and Tasman Sea, and a trough extending from the Southern Ocean into central Australia. A major decline in the mobility of the Australian aboriginal hunter-gatherer coincides with this MCA period, in southern central Australia.

  12. Drought Forecasting Using Stochastic Models in a Hyper-Arid Climate

    Directory of Open Access Journals (Sweden)

    Amr Mossad

    2015-03-01

    Full Text Available Drought forecasting plays a crucial role in drought mitigation actions. Thus, this research deals with linear stochastic models (autoregressive integrated moving average (ARIMA as a suitable tool to forecast drought. Several ARIMA models are developed for drought forecasting using the Standardized Precipitation Evapotranspiration Index (SPEI in a hyper-arid climate. The results reveal that all developed ARIMA models demonstrate the potential ability to forecast drought over different time scales. In these models, the p, d, q, P, D and Q values are quite similar for the same SPEI time scale. This is in correspondence with autoregressive (AR and moving average (MA parameter estimate values, which are also similar. Therefore, the ARIMA model (1, 1, 0 (2, 0, 1 could be considered as a general model for the Al Qassim region. Meanwhile, the ARIMA model (1, 0, 3 (0, 0, 0 at 3-SPEI and the ARIMA model (1, 1, 1 (2, 0, 1 at 24-SPEI could be generalized for the Hail region. The ARIMA models at the 24-SPEI time scale is the best forecasting models with high R2 (more than 0.9 and lower values of RMSE and MAE, while they are the least forecasting at the 3-SPEI time scale. Accordingly, this study recommends that ARIMA models can be very useful tools for drought forecasting that can help water resource managers and planners to take precautions considering the severity of drought in advance.

  13. Evaluation of the performance of solidified commercial low-level wastes in an arid climate

    International Nuclear Information System (INIS)

    Shallow land burial is being used as a disposal method for commercial low-level waste at waste disposal sites in arid (Hanford site near Richland, Washington) and humid (Barnwell, South Carolina) climatic regions. A field lysimeter facility has been established at the Hanford site in which to conduct waste-form leaching tests. The primary objective of this research is to determine typical source terms generated by commercial solidified low-level wastes. The field lysimeter facility consists of ten 3-m-deep by 1.8-m-diameter, closed-bottom lysimeters around a central instrument caisson, 4 m in diameter. Commercial cement and vinyl ester-styrene waste samples were removed from 210-L drums and placed in the 1.8-m-diameter lysimeters. Two bitumen samples are planned to be emplaced in the facility in 1984. The central caisson provides access to the instrumentation in the individual lysimeters and allows selective sampling of the soil and waste forms. Suction candles (ceramic cups) placed around the waste will be used to periodically collect soil water samples for chemical analysis. Meteorological data, moisture content, and soil temperature are automatically monitored at the facility. Characterization of the soils and waste forms have been partially completed. These data consist of moisture release characteristics, particle size distribution, concentrations and distributions of radionuclides in the waste forms, concentrations of radionuclides in the waste streams, and concentrations of hydrophilic organic species in one of the waste steams. 8 references, 3 figures, 5 tables

  14. A Risk-Based Assessment of Agricultural Water Scarcity Under Climate Change in a Semi-Arid and Snowmelt-Dominated River Basin

    OpenAIRE

    Moursi, Hossam

    2016-01-01

    Water scarcity is the major challenge that water managers face in semi-arid areas, especially in regions that depend on agriculture for rural livelihood. Climate change is one of the major stresses that is expected to exacerbate water scarcity problems in semi-arid regions. In this study, a risk-based approach was used to assess the climate change impacts on the risk of agricultural water scarcity in semi-arid and snowmelt-dominated river basins that are dependent on agriculture. The Sevier R...

  15. Performance of fenugreek bioinoculated with Rhizobium meliloti strains under semi-arid condition.

    Science.gov (United States)

    Singh, N K; Patel, D B

    2016-01-01

    Rhizobium meliloti strains were isolated from the fields of S.D. Agricultural University (Gujarat, India) and were maintained in the Congo Red Yeast Extract Mannitol Agar medium. These strains were tested for their effectiveness for fenugreek crop grown under semi-arid condition. Among the six Rhizobium strains, FRS-7 strain showed best plant growth parameters like shoot length, shoot dry weight, shoot total nitrogen, root length, root dry weight, root total nitrogen, seed yield, 1000 grain weight, number of root nodules, and nodules fresh and dry weight. The performance of this strain was better as compared to 20 kgN ha(-1) treatment through urea and was even far better over control plot. Seed yields obtained with FRS-7 during two years were 10.14 and 9.66 q ha(-1); which was about 36.8% and 45.9% high over control. This strain resulted in saving of about 20 kgN ha(-1) accompanied with better crop yield and soil health. Results of the present experiments can be utilized in integrated nutrient management for cultivation of fenugreek in semi-arid areas to provide sustainability to agricultural productivity in such regions. PMID:26930857

  16. Impact of grazing on range plant community components under arid Mediterranean climate in northern Syria

    NARCIS (Netherlands)

    Niane, A.A.

    2013-01-01

    Keywords: Rotational grazing, full protection, continuous grazing species richness, species diversity, soil seed bank, Bayesian methods, Salsola vermiculata, seed longevity, rangeland management, Syria.   Rangelands represent 70% of the semi-arid and arid Mediterranean land mass. It is a n

  17. Variation of climatic elements and thermoregulatory responses of goats in the Brazilian semi-arid

    Directory of Open Access Journals (Sweden)

    João Vinícius Barbosa Roberto

    2014-10-01

    Full Text Available This study aimed to evaluate the influence of climate elements in different times of day on the thermoregulatory mechanisms of Saanen goats pure and crossbred ¼ saanen+ ¾ Boer, reared in intensive system in semi-arid of Paraiba. Sixteen goats were used, eight females pure Saanen and eight crossbred ¼ Saanen + ¾ Boer, distributed in a DIC in a factorial scheme 2x12 (two races and twelve different times. Evaluated the environmental and physiological parameters in the different times: from 6 to 17 hours. In the environmental parameters is observed that IBGT increase during the day reaching its maximum value (84.16 at 13 hours. After 10 h of ambient temperatures exceeded the ZCT for goats. For TR observed that there was statistical difference between the genetic groups in times of 7, 10 and 16 hours, and the highest means found in the crossbreed and times of 13, 14,15 and 17 hours. For FR, the group of pure saanen and times of 14h showed the highest means. In the TS there was no effect of genetic groups. The variation of environmental temperature influences directly the physiological responses of animals. The group saanen is less tolerant than the crossbred, to semi-arid.

  18. Analysis of Molecular Geochemistry of Soil Organic Matter from 17-year Reciprocal Transplant Experiment in Arid Ecosystem: Simulated Climate Pertubation

    Science.gov (United States)

    Hess, N. J.; Tfaily, M.; Bailey, V. L.; McCue, L. A.

    2014-12-01

    Successful development of chemical profiles that link soil carbon vulnerability and resilience to climate change would greatly facilitate assessment of soil ecosystems response to global climate change. Additionally these signatures could be used to support the design of sustainable agricultural and food/energy crop security practices. We test this possibility using soils obtained from a 17-year reciprocal soil transplant experiment between two elevations in the arid environment of eastern Washington [1]. 30-cm diameter soil cores were reciprocally transplanted between the upper and lower sites. Cores were also transplanted in place to control for disturbance. Extracted subcores were incubated in environmental chambers and measured microbial respiration revealed statically a significant decrease in respiratory response as a function of temperature in cores transferred from low elevation to high elevation. We use ultra high resolution mass spectrometry to identify thousands of organic molecules and changes in geochemistry that would indicate the vulnerability of the soil ecosystem to climate perturbation. In our experiments we used methanol extraction followed by direct injection to 12 T ESI FT-ICR MS to identify about 4000 of individual compounds in about 200 mg soils at sub ppm mass accuracy. Chemical formulae were assigned to approximately 65% of the measured peaks using a modified Kujawinski pipeline and second order Kendrick transformations [2] resulted in approximately 75% assigned peaks. Our preliminary analysis finds that while the bulk C content of soils from the cooler, wetter conditions at the upper elevation is approximately twice that of the warmer, drier conditions at lower elevation, the molecular soil geochemistry is remarkably similar. Detailed analysis reveals subtle differences in the lipid, carbohydrate, and condensed hydrocarbon compositional makeup of the soil. Additionally, of the more than 17,000 individual compounds identified approximately

  19. Assessment of future agricultural conditions in southwestern Africa using fuzzy logic and high-resolution climate model scenarios

    OpenAIRE

    Weinzierl, Thomas; Heider, Katharina

    2015-01-01

    Climate change is expected to have a major impact on the arid savanna regions of southwestern Africa, such as the Okavango Basin. Precipitation is a major constraint for agriculture in countries like Namibia and Botswana and assessments of future crop growth conditions are in high demand. This GIS-based approach uses reanalysis data and climate model output for two scenarios and compares them to the precipitation requirements of the five most important crops grown in the region: maize, pearl ...

  20. Deuterium and 18O as indicators of evaporation losses from rice crops in semi-arid climate zones

    International Nuclear Information System (INIS)

    Rice requires the highest water application rate of any of the major grain crops, with total water demand per unit area of crop at least twice that of maize or wheat. Most of the water used for rice production in semi-arid climates is lost to the atmosphere through the combined effects of evaporation and transpiration. Evaporation leads to substantial enrichment of residual liquid phase water molecules containing heavier isotopes (deuterium and 18O) because of preferential loss to the atmosphere of lighter isotope molecules. In contrast, transpiration leads to little net enrichment of the heavier isotopes in residual waters. This difference between the effects on the stable isotopic composition of surface water of the two loss modes to the atmosphere offers the potential to estimate arid zone evaporation losses independent of transpiration, both in natural waters, such as swamps, and in regional scale irrigation networks. 3 refs, 2 figs

  1. DETERMINANTS OF CHOICE OF CROP VARIETY AS CLIMATE CHANGE ADAPTATION OPTION IN ARID REGIONS OF ZIMBABWE

    Directory of Open Access Journals (Sweden)

    James Zivanomoyo

    2013-03-01

    Full Text Available Impacts of climate change in developing countries remain poorly understood because few studies have successfully analyses the overall impact of climate on developing country economies. Agricultural growth is widely viewed as an effective and most important way to reduce poverty in developing countries which are hardly hit by the adverse effects of climate change (Datt and Ravallion, 1996. Despite this knowledge the main challenge is how to increase agricultural productivity to improve household welfare and increase food security in these changing and challenging climatic conditions. This study used the multinomial logit model to analyse the determinants of farmers' choice of crop variety in the face of climate change. The estimation of the multinomial logit was done by using the sorghum variety options as dependent variable and where farmers grow other crop different from sorghum as the reference state. Results show that the key determinants of choosing crop variety are; the price of existing crop variety, level of education of farmers, the size of the farms, government policies and incentives and credit availability.

  2. Impact of grazing on range plant community components under arid Mediterranean climate in northern Syria

    OpenAIRE

    Niane, A.A.

    2013-01-01

    Keywords: Rotational grazing, full protection, continuous grazing species richness, species diversity, soil seed bank, Bayesian methods, Salsola vermiculata, seed longevity, rangeland management, Syria.   Rangelands represent 70% of the semi-arid and arid Mediterranean land mass. It is a natural habitat for millions of people whose livelihood depends on animal husbandry. The revolutionary developments in the animal husbandry and veterinary medicines resulted in exponential increases in h...

  3. Simulating the impact of no-till systems on field water fluxes and maize productivity under semi-arid conditions

    Science.gov (United States)

    Mupangwa, W.; Jewitt, G. P. W.

    Crop output from the smallholder farming sector in sub-Saharan Africa is trailing population growth leading to widespread household food insecurity. It is therefore imperative that crop production in semi-arid areas be improved in order to meet the food demand of the ever increasing human population. No-till farming practices have the potential to increase crop productivity in smallholder production systems of sub-Saharan Africa, but rarely do because of the constraints experienced by these farmers. One of the most significant of these is the consumption of mulch by livestock. In the absence of long term on-farm assessment of the no-till system under smallholder conditions, simulation modelling is a tool that provides an insight into the potential benefits and can highlight shortcomings of the system under existing soil, climatic and socio-economic conditions. Thus, this study was designed to better understand the long term impact of no-till system without mulch cover on field water fluxes and maize productivity under a highly variable rainfall pattern typical of semi-arid South Africa. The simulated on-farm experiment consisted of two tillage treatments namely oxen-drawn conventional ploughing (CT) and ripping (NT). The APSIM model was applied for a 95 year period after first being calibrated and validated using measured runoff and maize yield data. The predicted results showed significantly higher surface runoff from the conventional system compared to the no-till system. Predicted deep drainage losses were higher from the NT system compared to the CT system regardless of the rainfall pattern. However, the APSIM model predicted 62% of the annual rainfall being lost through soil evaporation from both tillage systems. The predicted yields from the two systems were within 50 kg ha -1 difference in 74% of the years used in the simulation. In only 9% of the years, the model predicted higher grain yield in the NT system compared to the CT system. It is suggested that

  4. Assessment of adaptability of zebu cattle ( Bos indicus) breeds in two different climatic conditions: using cytogenetic techniques on genome integrity

    Science.gov (United States)

    Kumar, Anil; Waiz, Syma Ashraf; Sridhar Goud, T.; Tonk, R. K.; Grewal, Anita; Singh, S. V.; Yadav, B. R.; Upadhyay, R. C.

    2016-06-01

    The aim of this study was to evaluate the genome integrity so as to assess the adaptability of three breeds of indigenous cattle reared under arid and semi-arid regions of Rajasthan (Bikaner) and Haryana (Karnal) India. The cattle were of homogenous group (same age and sex) of indigenous breeds viz. Sahiwal, Tharparkar and Kankrej. A total of 100 animals were selected for this study from both climatic conditions. The sister chromatid exchanges (SCE's), chromosomal gaps and chromatid breaks were observed in metaphase plates of chromosome preparations obtained from in vitro culture of peripheral blood lymphocytes. The mean number of breaks and gaps in Sahiwal and Tharparkar of semi-arid zone were 8.56 ± 3.16, 6.4 ± 3.39 and 8.72 ± 2.04, 3.52 ± 6.29, respectively. Similarly, the mean number of breaks and gaps in Tharparkar and Kankrej cattle of arid zone were 5.26 ± 1.76, 2.74 ± 1.76 and 5.24 ± 1.84, 2.5 ± 1.26, respectively. The frequency of SCEs in chromosomes was found significantly higher ( P differences ( P different zones, i.e. arid and semi-arid, whereas no significant difference ( P > 0.05) was observed in the same zone. The analysis of frequency of CAs and SCEs revealed significant effects of environmental conditions on the genome integrity of animals, thereby indicating an association with their adaptability.

  5. Productivity and residual benefits of grain legumes to sorghum under semi-arid conditions in southwestern Zimbabwe

    NARCIS (Netherlands)

    Ncube, B.; Twomlow, S.J.; Wijk, van M.T.; Dimes, J.P.; Giller, K.E.

    2007-01-01

    The productivity and residual benefits of four grain legumes to sorghum (Sorghum bicolor) grown in rotation were measured under semi-arid conditions over three cropping seasons. Two varieties of each of the grain legumes; cowpea (Vigna unguiculata); groundnut (Arachis hypogaea); pigeon pea (Cajanus

  6. Adaptation to New Climate by an Old Strategy? Modeling Sedentary and Mobile Pastoralism in Semi-Arid Morocco

    Directory of Open Access Journals (Sweden)

    Korbinian P. Freier

    2014-07-01

    Full Text Available In a modeling study we examine vulnerability of income from mobile (transhumant pastoralism and sedentary pastoralism to reduced mean annual precipitation (MAP and droughts. The study is based on empirical data of a 3410 km2 research region in southern, semi-arid Morocco. The land use decision model integrates a meta-model of the Environmental Policy Integrated Climate (EPIC simulator to depict perennial and annual forage plant development. It also includes livestock dynamics and forward-looking decision making under uncertain weather. Mobile livestock in the model moves seasonally, sedentary livestock is restricted to pastures around settlements. For a reduction of MAP by 20%, our model shows for different experimental frequencies of droughts a significant decrease of total income from pastoralism by 8%–19% (p < 0.05. Looking separately at the two modes of pastoralism, pronounced income losses of 18%–44% (p < 0.05 show that sedentary pastoralism is much more vulnerable to dryer climate than mobile pastoralism, which is merely affected. Dedicating more pasture area and high quality fodder to mobile pastoralism significantly abates impacts from reduced MAP and droughts on total income by 11% (p < 0.05. Our results indicate that promotion of mobile pastoralism in semi-arid areas is a valuable option to increase resilience against climate change.

  7. Water, land, climate change and agrarian livelihood in an arid region riparian corridor: Rayón, Sonora, Mexico

    Science.gov (United States)

    Lee, R.; Scott, C. A.; Curl, K.; House-Peters, L.; Buechler, S.

    2012-12-01

    Results of recent fieldwork in Rayón, Sonora, Mexico (funded by NSF's "Strengthening Resilience of Arid Region Riparian Corridors") indicate that the coupled natural and human (CNH) system that has persisted since the town's founding in 1626 is being degraded and destabilised by a confluence of social and ecological pressures. System change or loss of key system services and products has important implications for ecological services and human economic activity in the riparian corridor. Less water quantity is the primary factor responsible for driving system degradation and change. Drought caused by climate change is widely perceived by agriculturists as responsible for reduced water quantity in the riparian area. Reductions in water quantity are so severe that the once perennial Rio San Miguel did not run during 2012's summer months for the first time in residents' memory. Ninety-percent of wells are dry. Fields irrigated by surface-water acequias were not planted. Starvation or dehydration has thinned herd sizes. Residents fear they will lose the ability to practice their traditional livelihoods: ranching, farming and cheese production. Drought conditions and resource management in response to climatic change have had a net negative impact on ecological services. Agriculturists have responded to less forage and pasture for cattle by clearing mesquite forests, putting land into production, and increasing water demand. From interviews it appears this process is cyclical: agriculturists widely believe access to more water or an end to the drought are the only ways to improve conditions. Interviews also reveal (a) agriculturists view technology, especially that which is able to improve water-use efficiency, as means to reduce stress in the CNH system and (b) a holistic view that couples natural well-being to human well-being is absent from the majority of respondents' worldviews. Technological and adoption of holistic perceptions are adaptations that may potentially

  8. Impacts of Climate Change and Anthropogenic Activities on the Ecological Restoration of Wetlands in the Arid Regions of China

    Directory of Open Access Journals (Sweden)

    Haibo Wang

    2016-03-01

    Full Text Available As an important part of the global ecosystem, wetlands and their dynamics greatly influence regional eco-environment systems. To understand the distributions, change processes and temporal-spatial characteristics of the wetlands of the inland river basin in an arid region (Heihe River Basin, HRB, this paper employed multi-source remote sensing data to facilitate multi-temporal monitoring of the HRB wetland using a wetland information extraction method. First, we performed monitoring of these wetlands for the years 2000, 2007, 2011 and 2014; then, we analyzed the variation characteristics of the spatial-temporal dynamics of the wetlands in the HRB over the last 15 years via the landscape dynamic change model and the transformation matrix. In addition, we studied the possible driving mechanisms of these changes. The research results showed that the total area of the HRB wetlands had decreased by 2959.13 hectares in the last 15 years (Since 2000, and the annual average loss was −1.09%. The dynamics characterizing the HRB wetlands generally presented a trend of slow increase after an initial decrease, which can be classified into three stages. From 2000 to 2007, the total wetland area rapidly decreased; from 2007 to 2011, the area slowly decreased; and from 2011 to 2014, the area gradually increased. The dynamic changing processes characterizing the wetland resources were ascribed to a combination of natural processes and human activities. The main driving mechanisms of wetland dynamic changes include climatic conditions, upper reach water inflows, population, water resources, cultivated area, and policy. The findings of this study can served as reference and support for the conservation and management of wetland resources in the HRB.

  9. Water balance of two earthen landfill caps in a semi-arid climate

    Energy Technology Data Exchange (ETDEWEB)

    Khire, M.V. [GeoSyntec Consultants, Boca Raton, FL (United States); Benson, C.H.; Bosscher, P.J. [Univ. of Wisconsin, Madison, WI (United States)

    1997-12-31

    Water balance data are presented that were obtained from two earthen cap test sections located in a semi-arid region. The test sections were constructed on a municipal solid waste landfill in East Wenatchee, Washington, USA. One test section represents a traditional resistive barrier, and is constructed with a compacted silty clay barrier 60 cm thick and a vegetated silty clay surface layer 15 cm thick. The other test section represents a capillary barrier and has a sand layer 75 cm thick overlain by a 15-cm-thick vegetated surface layer of silt. Extensive hydrological and meteorological data have been collected since November 1992. Unsaturated hydraulic properties of soils, hydrologic parameters, and vegetation have been extensively characterized. Results of the study show that capillary barriers can be effective caps in semi-arid and arid regions. They are also cheaper to construct and can perform better than traditional resistive barriers.

  10. Incidence of Vector-borne Disease and Climate Change: A Study in Semi-arid Algeria

    Science.gov (United States)

    Blakey, T.; Bounoua, L.

    2012-12-01

    Leishmaniases are among the most important emerging and resurging vector-borne diseases, second only to malaria in terms of the number of affected people. Leishmaniases are endemic in 88 countries worldwide and threaten about 350 million people (WHO, 2007). Since the first reported case of zoonotic cutaneous leishmaniasis (ZCL) in Saida, Algeria in 1991, 1,275 cases have been recorded (Makhlouf & Houti, 2010) with the vast majority of study-area cases (99%) reported between the years of 2000 and 2009. An investigation of potential climatic indicators for the apparent shift in disease prevalence was conducted by comparing anomalies in the climate data specific to the local pathogen cycle. It was determined that long term climate trends have resulted in conditions that promote the prevalence of ZCL. Increased precipitation have resulted in greater vegetation and promoted host and vector population growth through a trophic cascade. Increased minimum temperatures have lengthened the annual duration of sandfly activity. Short term variations in maximum temperatures, however show a correlation with disease suppression in the subsequent years. These findings indicate a potential to forecast the risk of ZCL infection through models of the trophic cascade and sandfly population growth.

  11. Evaluating the coupling effects of climate aridity and vegetation restoration on soil erosion over the Loess Plateau in China.

    Science.gov (United States)

    Zhang, Baoqing; He, Chansheng; Burnham, Morey; Zhang, Lanhui

    2016-01-01

    In this study, the coupling effects of climate aridity and vegetation restoration on runoff and sediment yield over the Loess Plateau were examined and characterized. To take into consideration the complexity of drought, as well as the varied strengths and weaknesses of different drought measures, two drought indices are selected to identify and evaluate drought variability. The Normalized Difference Vegetation Index (NDVI) data were obtained to monitor and express spatiotemporal variations in vegetation cover. The results show that most regions of the Loess Plateau experienced increasingly severe droughts over the past 40years, and these regions comprise the major source of the Yellow River sediment. Climatic drying initially occurred in the 1990s, and became statistically significant in 2000s. The increasingly severe droughts could negatively impact surface and groundwater supplies as well as soil water storage, but may also minimize surface runoff yield, which is one of the major causes of soil erosion on the Loess Plateau. Vegetation cover on the Loess Plateau was significantly improved after the implementation of "Grain for Green" project, which were helpful for controlling severe soil erosion. With the impacts of the construction of check dams, terraces and large reservoirs, runoff and sediment yield over the Loess Plateau initially exhibited downward trends between 1970 and 1990. After 1990, with the effects of the climate warming and drying, a second sharp reduction in runoff and sediment yield occurred. The coupling effects of climate aridity and vegetation restoration have led to a third significant decrease in runoff and sediment yield over the Loess Plateau after 2000. PMID:26379259

  12. Wind energy under cold climate conditions

    Energy Technology Data Exchange (ETDEWEB)

    Maribo Pedersen, B.

    1999-03-01

    There is an increasing interest in wind energy production under different climatic conditions, among them cold climate and icing conditions. More and more wind turbines are being installed in cold climates and even adapted technology has been developed for that environment. Various national activities are going on in at least Finland, Canada, Italy, Sweden, etc. and international collaboration has been carried out within the European Union's Non-nuclear energy programme. Wind turbine operation is affected by both the cold temperatures and the formation of ice on the blades and the supporting structure. Cold temperatures can be handled by material selections known in other technical fields but to prevent icing, new techniques have to be - and have been - developed. Icing affects the reliability of anemometers, which concerns both turbine control and resource estimation, and changes the aerodynamics of the blades, which eventually stops the turbine. In addition, occasional icing events can locally affect public safety. The development of applied technology has entered some different paths and different solutions are tried out. As the applications are entering a commercial phase, these is a request to gather the experiences and monitor the reliability in a form that can be utilised by developers, manufactureres, consultants and other tenderers. The Topical Experts Meeting will focus on site classification, operational experiences, modelling and mesurements of ice induced loads and safety aspects. (EHS)

  13. [Spatial variability of surface soil moisture content in depression area of karst region under moist and arid conditions].

    Science.gov (United States)

    Zhang, Jiguang; Chen, Hongsong; Su, Yirong; Wu, Jinshui; Zhang, Wei

    2006-12-01

    By the methods of geostatistics, this paper studied the spatial structure and distribution pattern of surface soil (0 - 5 and 5 - 10 cm) moisture content in the depression area of karst region in northwest Guangxi under moist and arid conditions in the forepart of dry season. The results showed that in test area, surface soil moisture content had obvious spatial heterogeneity and anisotropy, presenting a significantly different plaque distribution pattern. Under moist condition, surface soil moisture content had a medium or stronger spatial relativity, with a range of about 33.15 and 15.75 m, respectively, and an obvious trend effect in 0 - 5 cm soil layer. Under arid condition, the spatial relativity was strong, and the spatial scale of resembling plaque had somewhat decrease, with the smallest range being 8.22 m. The moisture content under arid condition had a higher spatial variability, and thus, the sampling strategy should be based on the mean soil moisture content. The significant difference in the spatial variability and distribution pattern of surface soil moisture in test area was mainly due to the effects of physiognomy, soil mean moisture (precipitation), and topography. PMID:17330464

  14. Productivity and residual benefits of grain legumes to sorghum under semi-arid conditions in southwestern Zimbabwe

    OpenAIRE

    Ncube, B.; Twomlow, S.J.; Wijk, van, M.J.; Dimes, J.P.; Giller, K.E.

    2007-01-01

    The productivity and residual benefits of four grain legumes to sorghum (Sorghum bicolor) grown in rotation were measured under semi-arid conditions over three cropping seasons. Two varieties of each of the grain legumes; cowpea (Vigna unguiculata); groundnut (Arachis hypogaea); pigeon pea (Cajanus cajan); Bambara groundnut (Vigna subterranea), and sorghum were grown during the first season. The same experiment was implemented three times in different, but adjacent fields that had similar soi...

  15. Evaporative fraction as an indicator of moisture condition and water stress status in semi-arid rangeland ecosystems

    OpenAIRE

    Francesco Nutini; Mirco Boschetti; Gabriele Candiani; Stefano Bocchi; Pietro Alessandro Brivio

    2014-01-01

    Rangeland monitoring services require the capability to investigate vegetation condition and to assess biomass production, especially in areas where local livelihood depends on rangeland status. Remote sensing solutions are strongly recommended, where the systematic acquisition of field data is not feasible and does not guarantee properly describing the spatio-temporal dynamics of wide areas. Recent research on semi-arid rangelands has focused its attention on the evaporative fraction (EF), a...

  16. Vulnerability of riparian ecosystems to elevated CO2 and climate change in arid and semiarid western North America

    Science.gov (United States)

    Perry, Laura G.; Andersen, Douglas C.; Reynolds, Lindsay V.; Nelson, S. Mark; Shafroth, Patrick B.

    2012-01-01

    Riparian ecosystems, already greatly altered by water management, land development, and biological invasion, are being further altered by increasing atmospheric CO2 concentrations ([CO2]) and climate change, particularly in arid and semiarid (dryland) regions. In this literature review, we (1) summarize expected changes in [CO2], climate, hydrology, and water management in dryland western North America, (2) consider likely effects of those changes on riparian ecosystems, and (3) identify critical knowledge gaps. Temperatures in the region are rising and droughts are becoming more frequent and intense. Warmer temperatures in turn are altering river hydrology: advancing the timing of spring snow melt floods, altering flood magnitudes, and reducing summer and base flows. Direct effects of increased [CO2] and climate change on riparian ecosystems may be similar to effects in uplands, including increased heat and water stress, altered phenology and species geographic distributions, and disrupted trophic and symbiotic interactions. Indirect effects due to climate-driven changes in streamflow, however, may exacerbate the direct effects of warming and increase the relative importance of moisture and fluvial disturbance as drivers of riparian ecosystem response to global change. Together, climate change and climate-driven changes in streamflow are likely to reduce abundance of dominant, native, early-successional tree species, favor herbaceous species and both drought-tolerant and late-successional woody species (including many introduced species), reduce habitat quality for many riparian animals, and slow litter decomposition and nutrient cycling. Climate-driven changes in human water demand and associated water management may intensify these effects. On some regulated rivers, however, reservoir releases could be managed to protect riparian ecosystem. Immediate research priorities include determining riparian species' environmental requirements and monitoring riparian

  17. Effectiveness of indirect evaporative cooling and thermal mass in a hot arid climate

    Energy Technology Data Exchange (ETDEWEB)

    Krueger, Eduardo [Programa de Pos-Graduacao em Tecnologia/Programa de Pos-Graduacao em Engenharia Civil, Departamento de Construcao Civil, Universidade Tecnologica Federal do Parana - UTFPR, Av. Sete de Setembro, 3165. Curitiba PR, CEP. 80230-901 (Brazil); Gonzalez Cruz, Eduardo [Instituto de Investigaciones de la Facultad de Arquitectura y Diseno (IFAD), Universidad del Zulia, Nucleo Tecnico de LUZ, Av. Goajira (16) con Calle 67, Maracaibo, CP 4011-A-526 (Venezuela); Givoni, Baruch [Department of Architecture, School of Arts and Architecture, UCLA, Los Angeles CA, USA, and Ben Gurion University (Israel)

    2010-06-15

    In this paper, we compare results of a long-term temperature monitoring in a building with high thermal mass to indoor temperature predictions of a second building that uses an indirect evaporative cooling system as a means of passive cooling (Vivienda Bioclimatica Prototipo -VBP-1), for the climatic conditions of Sde Boqer, Negev region of Israel (local latitude 30 52'N, longitude 34 46'E, approximately 480 m above sea level). The high-mass building was monitored from January through September 2006 and belongs to a student dormitory complex located at the Sde Boqer Campus of Ben-Gurion University. VBP-1 was designed and built in Maracaibo, Venezuela (latitude 10 34'N, longitude 71 44'W, elevation 66 m above sea level) and had its indoor air temperatures, below and above a shaded roof pond, as well as the pond temperature monitored from February to September 2006. Formulas were developed for the VBP-1, based on part of the whole monitoring period, which represent the measured daily indoor maximum, average and minimum temperatures. The formulas were then validated against measurements taken independently in different time periods. The developed formulas were here used for estimating the building's thermal and energy performance at the climate of Sde Boqer, allowing a comparison of two different strategies: indirect evaporative cooling and the use of thermal mass. (author)

  18. Surficial weathering of iron sulfide mine tailings under semi-arid climate

    OpenAIRE

    Hayes, Sarah M.; Root, Robert A.; Perdrial, Nicolas; Maier, Raina; Chorover, Jon

    2014-01-01

    Mine wastes introduce anthropogenic weathering profiles to the critical zone that often remain unvegetated for decades after mining cessation. As such, they are vulnerable to wind and water dispersion of particulate matter to adjacent ecosystems and residential communities. In sulfide-rich ore tailings, propagation to depth of the oxidative weathering front controls the depth-variation in speciation of major and trace elements. Despite the prevalence of surficial mine waste deposits in arid r...

  19. Groundwater Diffuse Recharge and its Response to Climate Changes in Semi-Arid Northwestern China

    Directory of Open Access Journals (Sweden)

    Lin Deng

    2015-01-01

    Full Text Available Understanding the processes and rates of groundwater recharge in arid and semi-arid areas is crucial for utilizing and managing groundwater resources sustainably. We obtained three chloride profiles of the unsaturated-zone in the desert/loess transition zone of northwestern China and reconstructed the groundwater recharge variations over the last 11, 21, and 37 years, respectively, using the generalized chloride mass balance (GCMB method. The average recharge rates were 43.7, 43.5, and 45.1 mm yr-1, respectively, which are similar to those evaluated by the chloride mass balance (CMB or GCMB methods in other semi-arid regions. The results indicate that the annual recharge rates were not in complete linear proportion to the corresponding annual precipitations, although both exhibited descending tendencies on the whole. Comparisons between the daily precipitation aggregate at different intensity and recharge rates reveal that the occurrence of relatively heavy daily precipitation per year may contribute to such nonlinearity between annual precipitation and recharge. The possible influences of vegetation cover alterations following precipitation change cannot be excluded as well. The approximately negative correlation between the average annual recharge and temperature suggests that changes in temperature have had significant influences on recharge.

  20. A Dynamic, Multivariate Sustainability Measure for Robust Analysis of Water Management under Climate and Demand Uncertainty in an Arid Environment

    Directory of Open Access Journals (Sweden)

    Christian Hunter

    2015-10-01

    Full Text Available Considering water resource scarcity and uncertainty in climate and demand futures, decision-makers require techniques for sustainability analysis in resource management. Through unclear definitions of “sustainability”, however, traditional indices for resource evaluation propose options of limited flexibility by adopting static climate and demand scenarios, limiting analysis variables to a particular water-use group and time. This work proposes a robust, multivariate, dynamic sustainability evaluation technique and corresponding performance indicator called Measure of Sustainability (MoS for resource management that is more adapted to withstand future parameter variation. The range of potential future climate and demand scenarios is simulated through a calibrated hydrological model of Copiapó, Chile, a case study example of an arid watershed under extreme natural and anthropogenic water stresses. Comparing MoS and cost rankings of proposed water management schemes, this paper determines that the traditional evaluation method not only underestimates future water deficits, but also espouses solutions without considering uncertainties in supply and demand. Given the uncertainty of the future and the dependence of resources upon climate and market trajectories, the MoS methodology proposes solutions that, while perhaps are not the most optimal, are robust to variations in future parameter values and are thus the best water management options in a stochastic natural world.

  1. Agricultural water supply/demand changes under projected future climate change in the arid region of northwestern China

    Science.gov (United States)

    Guo, Ying; Shen, Yanjun

    2016-09-01

    The water resources in the arid region of northwestern China, which are impacted by climate change, tend to be more unstable, and the environment and ecosystems will suffer from severe water shortage. In this paper, potential future climate trends were predicted based on CMIP5 simulations in this region. The water availability and agricultural water demand under future climate change scenarios were estimated. Impacted by increases in temperature, the irrigation water demand will increase by 4.27-6.15 billion m3 in this region over the next 60 years, compared to the demand of 32.75 billion m3 during 1971-2000. However, the annual runoff will only increase by 4.8-8.5 billion m3, which is equivalent to or even less than the increased irrigation water demand. In fact, the increased demand for industrial, domestic and ecological water were not considered here. Thus, the water supply/demand contradiction will result in more severe water shortages in the future. According to a comparison with simulated irrigation water demand under three adaptation strategy scenarios, we should take effective measures such as improving the efficiency of irrigation water utilization, reducing crop planting areas and adjusting crop planting structures to alleviate the impacts of future climate changes and human activities on the water supply and water use in this region.

  2. Relationship between Arid Climatic Factors and Forest Fires%干旱气候因子与森林火灾

    Institute of Scientific and Technical Information of China (English)

    徐明超; 马文婷

    2012-01-01

    Forest fires as a natural disaster,climate changes can directly or indirectly be affected on the forest burning in the fire environment,and thus affecting on fire occurrence and fire behavior.Arid climatic conditions such as temperature,sunlight,evaporation,wind,air humidity,and other weather conditions are closely related to occurrences of forest fires and development.In general,high temperature,drought,less humidity,large winds can easily trigger to forest fires.In the mountains,the valley wind and topographic effects on forest fire spread,the spread of forest fires mainly affected by the valley wind control,with the intermittent addition,the terrain changes to a large extent restricts the spread of fire.Thus,to take advantage of the different periods of weather conditions,mountain wind time and favorable terrain,timely organization of fire fighting and control the spread of fire.There are various types of forest fires,forest fires in some special fire behavior and related elements of the spread of fire development impact are analysis,to find out the forest fire fighting and escape methods and precautions.%森林火灾作为一种自然灾害,气候变化直接或间接影响森林燃烧的火环境,进而对火发生和火行为产生影响.干旱气候条件与森林火灾的发生有密切的关系,气象条件通过气温、日照、蒸发量、风力、空气湿度等影响着森林火灾的发生和发展.一般情况下,气温高、降水少、湿度小、风力大易发生森林火灾.在山区,山谷风和地形影响森林火灾蔓延,森林火灾的蔓延主要受山谷风所控制,具有间歇性,另外地形的变化在很大程度上制约着火势的蔓延.所以,要利用不同时段的气象条件、山风出现的时间及有利地形,及时组织灭火和控制火势蔓延.森林火灾的发生有各种类型,通过对森林火灾中一些特殊火行为及相关元素对火灾发展蔓延影响分析,找出森林火灾扑救与逃生的方法及注意事项.

  3. Short Communication: Rhizosphere bacteria containing ACC-deaminase conferred drought tolerance in wheat grown under semi-arid climate

    Directory of Open Access Journals (Sweden)

    Masood Ahmad Shakir

    2012-05-01

    Full Text Available Certain rhizobacteria have the potential of lowering endogenous ethylene levels in plants because of their 1- aminocyclopropane-1-carboxylate (ACC-deaminase activity and promoting root growth. This mechanism is of great agronomic significance under stress environments, which are known to induce accelerated production of ethylene. Thirty rhizobacteria were isolated from rhizosphere of wheat (Triticum aestivum L. growing in the Southern Punjab, a semi-arid region of Pakistan. Rhizobacteria were screened for ACC-deaminase activity and their potential to confer drought tolerance in wheat crop. Results of laboratory study revealed that selected rhizobacteria lowered endogenous ethylene levels in the rhizosphere as measured by Gas Chromatograph. Axenic studies showed that inoculation increased root-shoot length, root-shoot mass and lateral root number of the inoculated plants by 141, 44, 196, 52 and 30%, respectively, over control. Better-developed roots because of inoculation with plant growth promoting rhizobacteria (PGPR helped plants, a better crop stand that enhanced moisture and nutrient feeding volume resulting-in improved growth and yields of wheat crop. Two-year multi-location field trials inferred optimum yields with low delta water in semi-arid climate by PGPR containing ACC-deaminase. The enzyme ACC-deaminase probably lowered harmful ethylene levels which partially eliminated drought stress consequently utilizing soil moisture from lower profiles through proliferated roots.

  4. Ecological opportunity and the evolution of habitat preferences in an arid-zone bird: implications for speciation in a climate-modified landscape

    OpenAIRE

    Norman, Janette A.; Les Christidis

    2016-01-01

    Bioclimatic models are widely used to investigate the impacts of climate change on species distributions. Range shifts are expected to occur as species track their current climate niche yet the potential for exploitation of new ecological opportunities that may arise as ecosystems and communities remodel is rarely considered. Here we show that grasswrens of the Amytornis textilis-modestus complex responded to new ecological opportunities in Australia’s arid biome through shifts in habitat pre...

  5. Modelling vegetation water-use and groundwater recharge as affected by climate variability in an arid-zone Acacia savanna woodland

    Science.gov (United States)

    Chen, Chao; Eamus, Derek; Cleverly, James; Boulain, Nicolas; Cook, Peter; Zhang, Lu; Cheng, Lei; Yu, Qiang

    2014-11-01

    For efficient and sustainable utilisation of limited groundwater resources, improved understanding of how vegetation water-use responds to climate variation and the corresponding controls on recharge is essential. This study investigated these responses using a modelling approach. The biophysically based model WAVES was calibrated and validated with more than two years of field experimental data conducted in Mulga (Acacia aneura) in arid central Australia. The validated model was then applied to simulate vegetation growth (as changes in overstory and understory leaf area index; LAI), vegetation water-use and groundwater recharge using observed climate data for the period 1981-2012. Due to large inter-annual climatic variability, especially precipitation, simulated annual mean LAI ranged from 0.12 to 0.35 for the overstory and 0.07 to 0.21 for the understory. These variations in simulated LAI resulted in vegetation water-use varying greatly from year-to-year, from 64 to 601 mm pa. Simulated vegetation water-use also showed distinct seasonal patterns. Vegetation dynamics affected by climate variability exerted significant controls on simulated annual recharge, which was greatly reduced to 0-48 mm compared to that (58-672 mm) only affected by climate. Understanding how climate variability and land use/land cover change interactively impact on groundwater recharge significantly improves groundwater resources management in arid and semi-arid regions.

  6. Westerly jet stream and past millennium climate change in Arid Central Asia simulated by COSMO-CLM model

    Science.gov (United States)

    Fallah, Bijan; Sodoudi, Sahar; Cubasch, Ulrich

    2016-05-01

    This study tackles one of the most debated questions around the evolution of Central Asian climate: the "Puzzle" of moisture changes in Arid Central Asia (ACA) throughout the past millennium. A state-of-the-art Regional Climate Model (RCM) is subsequently employed to investigate four different 31-year time slices of extreme dry and wet spells, chosen according to changes in the driving data, in order to analyse the spatio-temporal evolution of the moisture variability in two different climatological epochs: Medieval Climate Anomaly (MCA) and Little Ice Age (LIA). There is a clear regime behavior and bimodality in the westerly Jet phase space throughout the past millennium in ACA. The results indicate that the regime changes during LIA show a moist ACA and a dry East China. During the MCA, the Kazakhstan region shows a stronger response to the westerly jet equatorward shift than during the LIA. The out-of-phase pattern of moisture changes between India and ACA exists during both the LIA and the MCA. However, the pattern is more pronounced during the LIA.

  7. Visible and Near-IR Reflectance Spectra of Mars Analogue Materials Under Arid Conditions for Interpretation of Martian Surface Mineralogy

    Science.gov (United States)

    Morris, R. V.; Graff, T. G.; Achilles, C. N.; Agresti, D. G.; Ming, D. W.; Golden, D. C.

    2011-01-01

    Visible and near-IR (VNIR) spectra from the hyper-spectral imagers MRO-CRISM and Mars Express OMEGA in martian orbit have signatures from Fe-bearing phases (e.g., olivine, pyroxene, and jarosite), H2O/OH-bearing phases (e.g., smectites and other phyllosilicates, sulfates, and high-SiO2 phases), and carbonate [e.g., 1-5]. Mineralogical assignments of martian spectral features are made on the basis of VNIR spectra acquired in the laboratory under appropriate environmental conditions on samples whose mineralogical composition is known. We report here additional results for our ongoing project [6] to acquire VNIR spectra under arid conditions.

  8. Climate change impact on future water resources availability for a semi-arid area (Ferghana Valley, Central Asia)

    Science.gov (United States)

    Radchenko, Iuliia; Breuer, Lutz; Mannig, Birgit; Frede, Hans-Georg

    2014-05-01

    Considering increasing temperatures and glacier recession during the last decades, it is of high interest to study the climate change impact on water resources availability in semi-arid regions of Central Asia. The Ferghana Valley is surrounded by the Tien-Shan and Pamiro-Alay mountain systems that store big amounts of water in snowpacks and glaciers. In the valley the agricultural activity of local people strongly depends on available water from the Syrdarya River. The river is formed by the confluence of the Naryn and Karadarya Rivers, which are mainly fed by the glacier and snow melt from the Akshiirak and Ferghana ridges of the aforementioned mountain systems. The small upper river basins of the valley also contribute with runoff (~34 %) to the Syrdarya River. These small rivers are mainly fed by precipitation and seasonal snow melt. Thus, because of climate change and glacier decline, it is necessary to investigate the comparative contribution of the small catchments versus two big river basins to the Syrdarya River system, as these small upper catchments could become more important for future water consumption. In this study the conceptual hydrological HBV-light model has been calibrated and validated for the period 1980-1985 over 18 upper catchments that feed the Syrdarya River from the surrounding mountain ridges. Dynamically downscaled climate change scenarios were then applied up to the year 2100 for these basins. The scenarios were generated by means of Global Circulation Model (ECHAM5) and Regional Climate Model (REMO) with a baseline period from 1971 till 2000. We will present modelling results of water resources, the contribution of small rivers to the Syrdarya River and to what extent this contribution is likely to change in the future. Moreover, the results of simulated potential runoff will be used to develop future climate change adaptation strategies regarding socio-economic and environmental sustainable water use.

  9. Climate change mitigation by carbon stock - the case of semi-arid West Africa

    Science.gov (United States)

    Lykke, A. M.; Barfod, A. S.; Tinggaard Svendsen, G.; Greve, M.; Svenning, J.-C.

    2009-11-01

    Semi-arid West Africa has not been integrated into the afforestation/reforestation (AR) carbon market. Most projects implemented under the Clean Development Mechanism (CDM) have focused on carbon emission reductions from industry and energy consumption, whereas only few (only one in West Africa) have been certified for AR carbon sequestration. A proposed mechanism, Reducing Emissions from Deforestation and Degradation (REDD) to be discussed under COP15 aims to reduce emissions by conserving already existing forests. REDD has high potential for carbon stocking at low costs, but focuses primarily on rain forest countries and excludes semi-arid West Africa from the preliminary setup. African savannas have potential to store carbon in the present situation with degrading ecosystems and relatively low revenues from crops and cattle, especially if it is possible to combine carbon stocking with promotion of secondary crops such as food resources and traditional medicines harvested on a sustainable basis. Methods for modelling and mapping of potential carbon biomass are being developed, but are still in a preliminary state. Although economic benefits from the sale of carbon credits are likely to be limited, carbon stocking is an interesting option if additional benefits are considered such as improved food security and protection of biodiversity.

  10. Climate change mitigation by carbon stock - the case of semi-arid West Africa

    International Nuclear Information System (INIS)

    Semi-arid West Africa has not been integrated into the afforestation/reforestation (AR) carbon market. Most projects implemented under the Clean Development Mechanism (CDM) have focused on carbon emission reductions from industry and energy consumption, whereas only few (only one in West Africa) have been certified for AR carbon sequestration. A proposed mechanism, Reducing Emissions from Deforestation and Degradation (REDD) to be discussed under COP15 aims to reduce emissions by conserving already existing forests. REDD has high potential for carbon stocking at low costs, but focuses primarily on rain forest countries and excludes semi-arid West Africa from the preliminary setup. African savannas have potential to store carbon in the present situation with degrading ecosystems and relatively low revenues from crops and cattle, especially if it is possible to combine carbon stocking with promotion of secondary crops such as food resources and traditional medicines harvested on a sustainable basis. Methods for modelling and mapping of potential carbon biomass are being developed, but are still in a preliminary state. Although economic benefits from the sale of carbon credits are likely to be limited, carbon stocking is an interesting option if additional benefits are considered such as improved food security and protection of biodiversity.

  11. Runoff from soils on marls under semi-arid mediterranean conditions

    OpenAIRE

    D. Garnet; Blum, W. E. H.

    1996-01-01

    In semi-arid Mediterranean regions the pressure on natural resources such as water and soil is increasing. In the Maghreb, soil degradation and reservoir sedimentation are serious problems, particularly in catchment areas with a high proportion of marls. As part of an Algerian-German project of scientific-technical cooperation, the runoff from soils on marls was studied, using modern rain simulators. A description of the rainfall experiments is followed by the presentation of a simple and app...

  12. Contribution of Afforestation Practices to Changing Hydrology in Arid and Semi-arid Regions

    Science.gov (United States)

    Xie, X.; Meng, S.; Li, J.

    2014-12-01

    Arid and semi-arid regions are generally susceptible to land degeneration due to limited precipitation and high potential evapotranspiration (ET). Afforestation has been assumed to be a feasible strategy to conserve water and to improve ecological environment. For example, the Northern China, as a typical arid and semi-arid region has experienced large-scale and long-term afforestation practices since the early 1980s. The land cover has been altered to some degree as tree planting with increasing greenness. However, the effectiveness of afforestation might not be as expected due to the interference of climate change. In this study, we attempted to quantify the contribution of afforestation practices to the hydrological system in the Northern China. A macro-scale hydrological model, i.e., the Variable Infiltration Capacity (VIC), was employed to simulate ET, soil moisture and runoff for the period 1959 - 2009. Fractional simulation scenarios were designed regarding different conditions of land cover and climate changes. The results indicate that the land cover has minor impact on the variability of hydrological variables at regional scale, comparing with the climate change. Particularly, the decreasing precipitation plays a dominant role in shaping the trends of ET, soil moisture and runoff. The findings have significant implications for the implementation of the afforestation practices and for the management of water resources in arid and semi-arid regions.

  13. Predicting the long-term durability of hemp-lime renders in inland and coastal areas using Mediterranean, Tropical and Semi-arid climatic simulations.

    Science.gov (United States)

    Arizzi, Anna; Viles, Heather; Martín-Sanchez, Inés; Cultrone, Giuseppe

    2016-01-15

    Hemp-based composites are eco-friendly building materials as they improve energy efficiency in buildings and entail low waste production and pollutant emissions during their manufacturing process. Nevertheless, the organic nature of hemp enhances the bio-receptivity of the material, with likely negative consequences for its long-term performance in the building. The main purpose of this study was to study the response at macro- and micro-scale of hemp-lime renders subjected to weathering simulations in an environmental cabinet (one year was condensed in twelve days), so as to predict their long-term durability in coastal and inland areas with Mediterranean, Tropical and Semi-arid climates, also in relation with the lime type used. The simulated climatic conditions caused almost unnoticeable mass, volume and colour changes in hemp-lime renders. No efflorescence or physical breakdown was detected in samples subjected to NaCl, because the salt mainly precipitates on the surface of samples and is washed away by the rain. Although there was no visible microbial colonisation, alkaliphilic fungi (mainly Penicillium and Aspergillus) and bacteria (mainly Bacillus and Micrococcus) were isolated in all samples. Microbial growth and diversification were higher under Tropical climate, due to heavier rainfall. The influence of the bacterial activity on the hardening of samples has also been discussed here and related with the formation and stabilisation of vaterite in hemp-lime mixes. This study has demonstrated that hemp-lime renders show good durability towards a wide range of environmental conditions and factors. However, it might be useful to take some specific preventive and maintenance measures to reduce the bio-receptivity of this material, thus ensuring a longer durability on site. PMID:26551276

  14. Inductive analysis about the impact of climate warming on regional geomorphic evolution in arid area

    Science.gov (United States)

    Anayit, Mattohti; Abulizi, Mailiya

    2016-04-01

    Climate change on the surface of earth will produce a chain reaction among so many global natural environmental elements. Namely, all the issues will be affected by the climate change, just like the regional water environment, formation and development of landscape, plants and animals living environment, the survival of microorganisms, the human economic environment and health, and the whole social environment changes at well. But because of slow frequency of climate change and it is volatility change, its influence on other factors and the overall environmental performance is not obvious, and its reflection performs slowly. Using regional weather data, we calculated qualitatively and quantitatively and did analysis the impact of climate warming on Xinjiang (a province of China) geomorphic evolution elements, including the ground weather, erosion rate, collapse change, landslide occurrences changes and impact debris flow, combining the field survey and indoor test methods. Key words: climate change; the geomorphic induction; landscape change in river basin; Xinjiang

  15. Agronomic Importance of First Development of Chickpea (Cicer arietinum L. Under Semi-arid Conditions: II. Seed Imbibition

    Directory of Open Access Journals (Sweden)

    A. Oksel

    2012-01-01

    Full Text Available Due to the slowness growth and weakness of the first developments of chickpea (Cicer arietinum L., it could not combated with weeds and easiliy caught up by Ascochyta blight (Ascochyta rabiei (Pass Labr. disease. Additionally, due to biotic and abiotic stress factors, esp. at the late sowing, important seed yield losses could be happened. To be able to avoid from them is only possible to accelerate of its first development as possible as. So, one of the best solutions to is to use chemical compounds such as Humic Acid (HA known soil regulator under the semi-arid conditions. With this aim this research was performed in a Randomized Complete Block Design (RCBD with four replications under semi-arid field conditions during (2008/2009 and (2009/2010 in Turkiye. Two cultivars (V1 = Gokce and V2 = Ispanyol and four seed imbibition methods (A0 = 0, A1 = Tap Water, A2 = ½ Tap Water + ½ Humic acid (HA, A3 = Full HA, as w/w and seven yield components Plant Height (PH, Number of Branches per Plant (NBP, Number of Pods per Plant (NPP, First Pod Height (NFP, Number of Seeds per Pod (NSP, Seed Weight per Plant (SWP and 100-Seed weight (HSW were investigated. The PH and FPH were affected the A0, the NBP, NPP and NSP were affected the A2 and the SWP and HSW were given the varied but not clear responses according to varieties for all the parameters in A1. The A0 and A1 were encouraged the germination and top soil of the plant but, the A2 to A3 were encouraged root system’s development. It was concluded that the A2 is a promising method which makes the maximum and positive effect to the first development of the chickpea agronomy under the semi-arid conditions.

  16. Agronomic importance of first development of chickpea (Cicer arietinum L.) under semi-arid conditions: II. Seed imbibition.

    Science.gov (United States)

    Ulukan, H; Bayraktar, N; Oksel, A; Gursoy, M; Kocak, N

    2012-02-15

    Due to the slowness growth and weakness of the first developments of chickpea (Cicer arietinum L.), it could not combated with weeds and easily caught up by Ascochyta blight (Ascochyta rabiei (Pass) Labr.) disease. Additionally, due to biotic and abiotic stress factors, esp. at the late sowing, important seed yield losses could be happened. To be able to avoid from them is only possible to accelerate of its first development as possible as. So, one of the best solutions to is to use chemical compounds such as Humic Acid (HA) known soil regulator under the semi-arid conditions. With this aim this research was performed in a Randomized Complete Block Design (RCBD) with four replications under semi-arid field conditions during (2008/2009) and (2009/2010) in Turkiye. Two cultivars (V1 = Gokce and V2 = Ispanyol) and four seed imbibition methods (A0 = 0, A1 = Tap Water, A2 = 1/2 Tap Water + 1/2 Humic acid (HA), A3 = Full HA, as w/w) and seven yield components Plant Height (PH), Number of Branches per Plant (NBP), Number of Pods per Plant (NPP), First Pod Height (NFP), Number of Seeds per Pod (NSP), Seed Weight per Plant (SWP) and 100-Seed weight (HSW) were investigated. The PH and FPH were affected the A0, the NBP, NPP and NSP were affected the A2 and the SWP and HSW were given the varied but not clear responses according to varieties for all the parameters in A1. The A0 and A1 were encouraged the germination and top soil of the plant but, the A2 to A3 were encouraged root system's development. It was concluded that the A2 is a promising method which makes the maximum and positive effect to the first development of the chickpea agronomy under the semi-arid conditions. PMID:22816177

  17. Large-scale climate patterns and precipitation in an arid endorheic region: linkage and underlying mechanism

    Science.gov (United States)

    Shi, Pengfei; Yang, Tao; Zhang, Ke; Tang, Qiuhong; Yu, Zhongbo; Zhou, Xudong

    2016-04-01

    The interactions between a range of large-scale climate oscillations and their quantitative links with precipitation are basic prerequisites to understand the hydrologic cycle. Restricted by the current limited knowledge on underlying mechanisms, statistical methods (e.g. correlation methods) are often used rather than a physical-based model. However, available correlation methods generally fail to explain the interactions among a wide range of climate oscillations and associated effects on the water cycle. This study presents a new probabilistic analysis approach by means of a state-of-the-art Copula-based joint probability distribution to characterize the aggregated behaviors for large-scale climate patterns and their connections to precipitation. We applied this method to identify the complex connections between climate patterns (westerly circulation (WEC), El Niño-Southern Oscillation (ENSO) and Pacific Decadal Oscillation (PDO)) and seasonal precipitation over a typical endorheic region, the Tarim River Basin in central Asia. Results show that the interactions among multiple climate oscillations are non-uniform in most seasons and phases. Certain joint extreme phases can significantly trigger extremes (flood and drought) owing to the amplification effect among climate oscillations. We further find that the connection is mainly due to the complex effects of climatic and topographical factors.

  18. Influences on the stable oxygen and carbon isotopes in gerbillid rodent teeth in semi-arid and arid environments: Implications for past climate and environmental reconstruction

    Science.gov (United States)

    Jeffrey, Amy; Denys, Christiane; Stoetzel, Emmanuelle; Lee-Thorp, Julia A.

    2015-10-01

    The stable isotope composition of small mammal tissues has the potential to provide detailed information about terrestrial palaeoclimate and environments, because their remains are abundant in palaeontological and archaeological sites, and they have restricted home ranges. Applications to the Quaternary record, however, have been sparse and limited by an acute lack of understanding of small mammal isotope ecology, particularly in arid and semi-arid environments. Here we document the oxygen and carbon isotope composition of Gerbillinae (gerbil) tooth apatite across a rainfall gradient in northwestern Africa, in order to test the relative influences of the 18O/16O in precipitation or moisture availability on gerbil teeth values, the sensitivity of tooth apatite 13C/12C to plant responses to moisture availability, and the influence of developmental period on the isotopic composition of gerbil molars and incisors. The results show that the isotopic composition of molars and incisors from the same individuals differs consistent with the different temporal periods reflected by the teeth; molar teeth are permanently rooted and form around the time of birth, whereas incisors grow continuously. The results indicate that tooth choice is an important consideration for applications as proxy Quaternary records, but also highlights a new potential means to distinguish seasonal contexts. The oxygen isotope composition of gerbil tooth apatite is strongly correlated with mean annual precipitation (MAP) below 600 mm, but above 600 mm the teeth reflect the oxygen isotope composition of local meteoric water instead. Predictably, the carbon isotope composition of the gerbil teeth reflected C3 and C4 dietary inputs, however arid and mesic sites could not be distinguished because of the high variability displayed in the carbon isotope composition of the teeth due to the microhabitat and short temporal period reflected by the gerbil. We show that the oxygen isotope composition of small

  19. Simulation of Water Vapor Ingress into PV-Modules under Different Climatic Conditions

    Directory of Open Access Journals (Sweden)

    Philip Hülsmann

    2013-01-01

    Full Text Available This work deals with the simulation of water vapor ingress into wafer-based PV-modules for long-term exposure under different climatic conditions. Measured material parameters together with climatic data sets from four test sites (tropic, moderate, alpine, and arid were used to calculate the water concentration inside of the encapsulant between solar cell and glass for a lifetime of 20 years. Two back-sheet materials (PET-based and PA-based combined with EVA as encapsulant were used in respect to their influence on water ingress. The results show faster water ingress for warmer regions, but the highest concentrations were found for the moderate test site. The water ingress was additionally influenced by the used encapsulant and back-sheet combination. In particular the temperature dependency of the mass transfer, which differs from material to material, was the focus of this investigation.

  20. Effect of climate change on the vulnerability of a socio-ecological system in an arid area

    Science.gov (United States)

    Liu, Hai-Long; Willems, Patrick; Bao, An-Ming; Wang, Ling; Chen, Xi

    2016-02-01

    The vulnerability of arid areas threatens ecosystems and human existence. With climate change and increasing human activities, addressing this vulnerability has become an important concern. To support this objective, we present a complex index system to analyze vulnerability at a regional scale with a 1 km × 1 km resolution. Based on the evaluation framework, which includes natural resources, the natural environment and the social economy, the results indicate that an ecosystem in a mountainous area is more vulnerable than it is in a plain. Land desertification will worsen from 2014 to 2099 under the RCP4.5 scenarios and improve slightly under the RCP8.5 and RCP2.6 scenarios, while the suitable land for agriculture increased slightly under the three scenarios. In addition, a regional sensitivity analysis of vulnerability to climate change shows that the improving region and the worsening region will occupy 1.30% and 74.51%, respectively. In view of this, the socio-ecological system will undergo a worsening trend as a whole. Finally, we simplified how to solve the problem of a socio-ecological system in the future. This research method and results would generate new insights with respect to planning for sustainable development and provide a reference for decision-making.

  1. Assessment and analysis of industrial liquid waste and sludge disposal at unlined landfill sites in arid climate

    International Nuclear Information System (INIS)

    Municipal solid waste disposal sites in arid countries such as Kuwait receive various types of waste materials like sewage sludge, chemical waste and other debris. Large amounts of leachate are expected to be generated due to the improper disposal of industrial wastewater, sewage sludge and chemical wastes with municipal solid waste at landfill sites even though the rainwater is scarce. Almost 95% of all solid waste generated in Kuwait during the last 10 years was dumped in five unlined landfills. The sites accepting liquid waste consist of old sand quarries that do not follow any specific engineering guidelines. With the current practice, contamination of the ground water table is possible due to the close location of the water table beneath the bottom of the waste disposal sites. This study determined the percentage of industrial liquid waste and sludge of the total waste dumped at the landfill sites, analyzed the chemical characteristics of liquid waste stream and contaminated water at disposal sites, and finally evaluated the possible risk posed by the continuous dumping of such wastes at the unlined landfills. Statistical analysis has been performed on the disposal and characterization of industrial wastewater and sludge at five active landfill sites. The chemical analysis shows that all the industrial wastes and sludge have high concentrations of COD, suspended solids, and heavy metals. Results show that from 1993 to 2000, 5.14±1.13 million t of total wastes were disposed per year in all active landfill sites in Kuwait. The share of industrial liquid and sludge waste was 1.85±0.19 million t representing 37.22±6.85% of total waste disposed in all landfill sites. Such wastes contribute to landfill leachate which pollutes groundwater and may enter the food chain causing adverse health effects. Lined evaporation ponds are suggested as an economical and safe solution for industrial wastewater and sludge disposal in the arid climate of Kuwait

  2. Resilience of stocking capacity to changing climate in arid to Mediterranean landscapes

    OpenAIRE

    Köchy, Martin; Mathaj, Martin; Jeltsch, Florian; Malkinson, Dan

    2008-01-01

    Small livestock is an important resource for rural human populations in dry climates. How strongly will climate change affect the capacity of the rangeland? We used hierarchical modelling to scale quantitatively the growth of shrubs and annual plants, the main food of sheep and goats, to the landscape extent in the eastern Mediterranean region. Without grazing, productivity increased in a sigmoid way with mean annual precipitation. Grazing reduced productivity more strongly the drier the land...

  3. Assessment of adaptability of zebu cattle ( Bos indicus) breeds in two different climatic conditions: using cytogenetic techniques on genome integrity

    Science.gov (United States)

    Kumar, Anil; Waiz, Syma Ashraf; Sridhar Goud, T.; Tonk, R. K.; Grewal, Anita; Singh, S. V.; Yadav, B. R.; Upadhyay, R. C.

    2016-06-01

    The aim of this study was to evaluate the genome integrity so as to assess the adaptability of three breeds of indigenous cattle reared under arid and semi-arid regions of Rajasthan (Bikaner) and Haryana (Karnal) India. The cattle were of homogenous group (same age and sex) of indigenous breeds viz. Sahiwal, Tharparkar and Kankrej. A total of 100 animals were selected for this study from both climatic conditions. The sister chromatid exchanges (SCE's), chromosomal gaps and chromatid breaks were observed in metaphase plates of chromosome preparations obtained from in vitro culture of peripheral blood lymphocytes. The mean number of breaks and gaps in Sahiwal and Tharparkar of semi-arid zone were 8.56 ± 3.16, 6.4 ± 3.39 and 8.72 ± 2.04, 3.52 ± 6.29, respectively. Similarly, the mean number of breaks and gaps in Tharparkar and Kankrej cattle of arid zone were 5.26 ± 1.76, 2.74 ± 1.76 and 5.24 ± 1.84, 2.5 ± 1.26, respectively. The frequency of SCEs in chromosomes was found significantly higher ( P 0.05) was observed in the same zone. The analysis of frequency of CAs and SCEs revealed significant effects of environmental conditions on the genome integrity of animals, thereby indicating an association with their adaptability.

  4. Has contemporary climate change played a role in population declines of the lizard Ctenophorus decresii from semi-arid Australia?

    Science.gov (United States)

    Walker, Samantha; Stuart-Fox, Devi; Kearney, Michael R

    2015-12-01

    Whilst contemporary climatic changes are small in magnitude compared to those predicted for the coming decades, they have already been linked to species range shifts and local extinctions. Elucidating the drivers behind species' responses to contemporary climate change will better inform management strategies for vulnerable and pest species alike. A recent proposal to explain worldwide local extinctions in lizards is that increasing maximum temperatures have constrained lizard activity time in the breeding season beyond extinction thresholds. Here we document a significant population decline and potential local extinction at the warm (northern) range margin of the tawny dragon, Ctenophorus decresii, a rock-dwelling lizard from the Flinders Ranges in semi-arid Australia. We developed and tested a biophysical model of tawny dragon thermoregulatory behaviour and drove the model with daily weather data for the period 1990-2009 across the Flinders Ranges. Our results indicate that potential annual activity time has likely increased over this period throughout the historic range, with within-season declines only in the summer months at the northern range limit. However, populations that have declined since 2000 have also likely experienced higher active body temperatures and more stringent retreat-site requirements (deeper crevices) than have regions where the species remains common, during a period of declining rainfall. Our laboratory estimates of thermal preference in this species were insensitive to altered nutritional and hydric state. Thus it is possible that recent population declines are linked to desiccation stress driven by higher body temperatures and declining rainfall. Our study illustrates that simple indices of the impact of climate warming on animals, such as activity restriction, may in fact reflect a variety of potential mechanisms whose ultimate outcome will be contingent on other factors such as water and shelter availability. PMID:26615728

  5. An extended modeling approach to assess climate change impacts on groundwater recharge and adaptation in arid areas

    Directory of Open Access Journals (Sweden)

    H. Hashemi

    2014-10-01

    Full Text Available The impact of future climate scenarios on surface and groundwater resources was simulated using a modeling approach for an artificial recharge area in arid southern Iran. Future climate data for the periods of 2010–2030 and 2030–2050 were acquired from the Canadian Global Coupled Model (CGCM 3.1 for scenarios A1B, A2, and B1. These scenarios were adapted to the studied region using the delta-change method. The modified version of the HBV model (Qbox was used to simulate runoff in a flash flood prone catchment. The model was calibrated and validated for the period 2002–2011 using daily discharge data. The projected climate variables were used to simulate future runoff. The rainfall–runoff model was then coupled to a calibrated groundwater flow and recharge model (MODFLOW to simulate future recharge and groundwater hydraulic head. The results of the rainfall–runoff modeling showed that under the B1 scenario the number of floods might increase in the area. This in turn calls for a proper management, as this is the only source of fresh water supply in the studied region. The results of the groundwater recharge modeling showed no significant difference between present and future recharge for all scenarios. Owing to that, four abstraction and recharge scenarios were assumed to simulate the groundwater level and recharged water in the studied aquifer. The results showed that the abstraction scenarios have the most substantial effect on the groundwater level and the continuation of current pumping rate would lead to a groundwater decline by 18 m up to 2050.

  6. Effect of meteorologic conditions on total suspended particulate (TSP) levels and elemental concentration of aerosols in a semi-arid zone (Beer-Sheva, Israel)

    International Nuclear Information System (INIS)

    The total suspended particulate (TSP) levels in Beer-Sheva, situated in a semi-arid area with winds bringing in dust from the surrounding deserts, was measured 41 times between June 1977 and May 1978. The TSP levels are correlated with climatic conditions. High TSP levels (890 +- 250 μg m-3) were found during Sharav conditions and sandstorms (hot, dry weather, typical to this region). Low TSP levels (59 +- 28 μg m-3) were found in the winter following rain. Usual TSP levels were found to be 140 +- 20 μg m-3 occurring during normal weather conditions. The elemental composition of the Beer-Sheva aerosols were determined using instrumental neutron activation analysis (INNA) and X-ray Fluorescence (XRF). The concentrations of the following elements Fe, Na, Br, K, Sm, Au, Sb, Ga, La, Yb, Lu, Se, Hg, Cr, Sc, Rb, Co, Ta and Zn were determined by INNA and Ca, Si, S, Ti, Cl, Pb, Fe, V, Ni and Mn by XRF. Their relative abundances were found to depend on the prevailing TSP level. (Auth.)

  7. Evaluation of landfill leachate in arid climate-a case study.

    Science.gov (United States)

    Al-Yaqout, A F; Hamoda, M F

    2003-08-01

    Generation of leachate from municipal solid waste (MSW) landfill in arid regions has long been neglected on the assumption that minimal leachate could be formed in the absence of precipitation. Therefore, a case study was conducted at two unlined MSW landfills, of different ages, in the state of Kuwait in order to determine the chemical characteristics of leachate and examine the mechanism of leachate formation. Leachate quality data were collected from both active and old (closed) landfills where co-disposal of MSW and other solid and liquid wastes is practiced. The analysis of data confirms that leachates from both landfills are severely contaminated with organics, salts and heavy metals. However, the organic strength of the leachate collected from the old landfill was reduced due to waste decomposition and continuous gas flaring. A significant degree of variability was encountered and factors which may influence leachate quality were identified and discussed. A water balance at the landfill site was assessed and a conceptual model was presented which accounts for leachate generation due to rising water table, capillary water and moisture content of the waste. PMID:12742402

  8. Ecosystem services provided by agricultural terraces in semi-arid climates.

    Science.gov (United States)

    Romero-Díaz, Asunción; Díaz-Pereira, Elvira; Boix-Fayos, Carolina; de Vente, Joris

    2016-04-01

    Since ancient times, agricultural terraces are common features throughout the world, especially on steep slope gradients. Nowadays many terraces have been abandoned or removed and few new terraces are build due to increased mechanisation and intensification of agriculture. However, terraces are amongst the most effective soil conservation practices, reducing the slope gradient and slope length, as well as runoff rate and soil erosion, and without terraces, it would be impossible to cultivate on many hillslopes. Moreover, their scenic interest is undeniable, as in some cases, terraced slopes have even become part of UNESCO World Heritage. In order to highlight the potential benefits, requirements and limitations of terraces, we reviewed different types of sustainable land management practices related to terraces and characterised their implications for provisioning, regulating, supporting, and cultural ecosystem services. We centred our review on terraces in semi-arid environments worldwide, as were documented in the WOCAT (World Overview of Conservation Approaches and Technologies) database. Our results show that the most important ecosystem services provided by terraces relate to regulation of the on-site and off-site effects of runoff and erosion, and maintenance of soil fertility and vegetation cover. The presence of terraces also favours the provision of food, fiber, and clean water. In short, our results stress the crucial environmental, geomorphological and hydrological functions of terraces that directly relate to improving the quality of life of the people that use them. These results highlight the need for renewed recognition of the value of terraces for society, their preservation and maintenance.

  9. Improving Estimation of Evapotranspiration under Water-Limited Conditions Based on SEBS and MODIS Data in Arid Regions

    Directory of Open Access Journals (Sweden)

    Chunlin Huang

    2015-12-01

    Full Text Available This study proposes a method for improving the estimation of surface turbulent fluxes in surface energy balance system (SEBS model under water stress conditions using MODIS data. The normalized difference water index (NDWI as an indicator of water stress is integrated into SEBS. To investigate the feasibility of the new approach, the desert-oasis region in the middle reaches of the Heihe River Basin (HRB is selected as the study area. The proposed model is calibrated with meteorological and flux data over 2008–2011 at the Yingke station and is verified with data from 16 stations of the Heihe Watershed Allied Telemetry Experimental Research (HiWATER project in 2012. The results show that soil moisture significantly affects evapotranspiration (ET under water stress conditions in the study area. Adding the NDWI in SEBS can significantly improve the estimations of surface turbulent fluxes in water-limited regions, especially for spare vegetation cover area. The daily ET maps generated by the new model also show improvements in drylands with low ET values. This study demonstrates that integrating the NDWI into SEBS as an indicator of water stress is an effective way to improve the assessment of the regional ET in semi-arid and arid regions.

  10. Mediterranean semi-arid systems-sensitivity and adaptation

    International Nuclear Information System (INIS)

    The semi-arid areas of the Mediterranean are sensitive to climate change as they are located. In many cases, between two different systems, the arid system and the Mediterranean sub-humid system. A number of quick response ecogeomorphological variables were monitored along a climatic transect in Israel, running from west to east, covering an annual rainfall range of 700-100mm. The relationships of climatic conditions-available water soil properties overland flow erosion, were investigates. Soil samples were taken from open areas between shrubs and overland flow was monitored in posts of 7, 14 and 21 m in length (3m width). (Author)

  11. The effect of grazing on soil and water losses under arid and mediterranean climates. Implications for desertification

    OpenAIRE

    A. Cerdà; Lavée, H.

    1999-01-01

    Two sites, both affected by grazing but under different climatic conditions, were selected in Israel to study the effect of grazing on soil degradation. One site was selected in the Judean Desert, a dry environment (260 mm mean annual rainfall) with a long history of overgrazing and very little vegetative cover. The second site was selected in the Galilee Mountains where the climate is of Mediterranean type (650 mm mean annual rainfall) and the vegetative cover is much greater in spite of the...

  12. A 100-year record of climate change and human activities inferred from the geochemical composition of sediments in Chaiwopu Lake, arid northwest China

    Directory of Open Access Journals (Sweden)

    Wen Liu

    2016-01-01

    Full Text Available An 81-cm sediment core from Chaiwopu Lake in arid northwest China was analyzed for 137Cs activity and concentrations of major and trace elements. We used these data to discriminate between the influence of climate change and human activities on the geochemical change of the lake sediments over the past century. Elements Al, K, Ba, Ti, V, Fe, Ni, Mn, Li, and Be were mainly from detrital. Ca, Sr, and Mg concentrations were controlled by chemical weathering processes. Na came mainly from salt precipitation caused by a decline in water level. Enrichment factors for Pb and P in recent deposits are large, indicating they were influenced by human activies. Geochemical conditions during the past century can be divided into three stages: i From ca. 1900 to the1950s element concentrations varied widely and frequently. In general, concentrations of typical mobile elements Ca, Sr, and Mg stay relatively high whereas values for other elements remained relatively low. This was interpreted to reflect variable climate under conditions of weak surface erosion intensity. ii From the 1950s to the early 2000s, element concentrations display less variability. The Al, K, Ba, Ti, P, Cr, V, Fe, Ni, Mn, Co, Cu, Li, Zn, Be, Pb, and Na contents were generally higher, whereas contents of Ca, Sr, and Mg were on average lower. This indicates that the regional environment was conducive to surface erosion. Enrichment of trace metals and major elements in the sediment reflects enhanced human activities. iii In the last decade, Pb and P exhibited a great increase, possibly associated with the input from fossil fuel combustion, sewage discharge and non-point-source pollution in the watershed. The lake volume decreased substantially because of groundwater extraction for municipal water, which resulted in a marked increase in salinity and enhanced Na precipitation.

  13. The effect of grazing on soil and water losses under arid and mediterranean climates. Implications for desertification

    Directory of Open Access Journals (Sweden)

    Cerdà, A.

    1999-12-01

    Full Text Available Two sites, both affected by grazing but under different climatic conditions, were selected in Israel to study the effect of grazing on soil degradation. One site was selected in the Judean Desert, a dry environment (260 mm mean annual rainfall with a long history of overgrazing and very little vegetative cover. The second site was selected in the Galilee Mountains where the climate is of Mediterranean type (650 mm mean annual rainfall and the vegetative cover is much greater in spite of the grazing. Simulated rain experiments were performed in the field and in the laboratory in order to evaluate differences in hydrological and erosional response to rainfall between the two sites. The results show a clear difference between these two ecosystems. In the Judean Desert, where vascular plant cover is sparse, a crust was developed which enhanced overland flow and erosion. In the Mediterranean environment the overland flow and erosion were negligible under shrubs and relatively high at the intershrub corridors. At the hillslope scale a mosaiclike pattern of water and soil contributing and accepting patches was developed. Such a pattern usually protect the hillslope from being eroded. Runoff and erosion rates luere very high in the Judean Desert and negligible in the Galilee Mountains.

    [fr] Afin d'étudier l'effet du pâturage sur la dégradation des sols, deux zones de caractéristiques climatiques différentes soumises au pâturage ont été sélectionnées en Israel. L'une de ces zones se trouve située dans le désert de Judée, un milieu très aride (260 mm de précipitation annuelle moyenne avec un couvert végétal peu dense et une longue influence du surpâturage. La deuxième zone se trouve sur les montagnes de Galilée, caractérisées par un climat méditerranéen (650 mm de précipitation annuelle moyenne et un couvert végétal bien plus dense et ce malgré l'influence du pâturage. Afin d'évaluer le comportement hydrologique et

  14. The earliest well-dated archeological site in the hyper-arid Tarim Basin and its implications for prehistoric human migration and climatic change

    Science.gov (United States)

    Han, WenXia; Yu, LuPeng; Lai, ZhongPing; Madsen, David; Yang, Shengli

    2014-07-01

    The routes and timing of human occupation of the Tibetan Plateau (TP) are crucial for understanding the evolution of Tibetan populations and associated paleoclimatic conditions. Many archeological sites have been found in/around the Tarim Basin, on the northern margin of the Tibetan Plateau. Unfortunately, most of these sites are surface sites and cannot be directly dated. Their ages can only be estimated based on imprecise artifact comparisons. We recently found and dated an archeological site on a terrace along the Keriya River. Our ages indicate that the site was occupied at ~ 7.0-7.6 ka, making it the earliest well-dated archeological site yet identified in the Tarim Basin. This suggests that early human foragers migrated into this region prior to ~ 7.0-7.6 ka during the early to mid-Holocene climatic optimum, which may have provided the impetus for populating the region. We hypothesize that the Keriya River, together with the other rivers originating from the TP, may have served as access routes onto the TP for early human foragers. These rivers may also have served as stepping stones for migration further west into the now hyper-arid regions of the Tarim Basin, leading ultimately to the development of the Silk Road.

  15. Wavelet analysis of spring climate characteristics in arid aeolian area of agro-pastoral ecotone in China

    Directory of Open Access Journals (Sweden)

    Chun-xia ZOU

    2012-09-01

    Full Text Available The unique regional climate characteristics are among the main reasons for the frequent wind-sand activity in arid and cold areas in the agro-pastoral ecotone in Inner Mongolia, China. This paper focuses on the time series of temperature and precipitation in spring when sandstorms often occur in the area. Based on meteorological data for a 46-year period from 1959 to 2004, multi-scale variations and abrupt changes in temperature and precipitation were analyzed with the Mexican hat function (MHF wavelet method, showing the multi-scale variation characteristics of temperature and precipitation, as well as the periods and change points at different time scales. The relationship between temperature and precipitation was obtained using the wavelet analysis method. Obvious staggered features of the variations of spring temperature and precipitation were observed in this agro-pastoral ecotone. The strongest oscillation periods of spring temperature variations were 1 and 22 years, while for precipitation, the strongest oscillation periods of variations were 2, 8, and 22 years. In addition, lower spring temperature corresponded to lower precipitation, whereas higher temperature yielded higher precipitation rate.

  16. Impact of Reforestation on Local Climate and Environment in a Semi-arid Urban Valley, Northwestern China

    Science.gov (United States)

    Xia, D.; Yu, Y.; He, J.

    2015-12-01

    Since 1999 Chinese government has invested more than 800 million Yuan to reforest the southern and the northern mountains surrounding urban Lanzhou - a typical semi-arid city located in a river valley, Northwestern China. Until 2009 obvious land use change occurred, with 69.2% of the reforested area been changed from grasslands, croplands, barren or sparsely vegetated land to closed shrublands and 20.6% been changed from closed shrublands, grasslands, and croplands to forests. This study assesses the impact of these changes on local climate and environment in winter using WRF (Weather Research & Forecasting) model incorporated with high-resolution remotely sensed land cover data for 1999 and 2009 and the FLEXible PARTicle (FLEXPART) dispersion model. Results indicate that the changes in albedo, surface exchange coefficient and surface soil heat conductivity related to the reforestation led to the changes in surface net radiation and the surface energy partitioning, which in turn affected the meteorology fields and enhanced the mountain-valley wind circulation. The amount of air exchanged between the valley and the outside increased after reforestation during the day, with the largest increase of 10 %, while it changed little during the night on winter sunny day with no snow cover. The sensitivity analysis using FLEXPART-WRF model indicates that the reforestation affected the spatial distribution of pollutants and slightly improved the urban air quality in winter. And the greening program of Lanzhou has special reference to other valley urbans.

  17. Event based recharge assessment from soil moisture monitoring sites under a steep Mediterranean - semi-arid climatic gradient

    Science.gov (United States)

    Ries, Fabian; Sauter, Martin; Lange, Jens

    2014-05-01

    The unsaturated soil zone is of fundamental importance for the understanding of temporal and spatial variability of groundwater recharge. This is especially true for the Mediterranean region where a large fraction of long-term groundwater recharge occurs during above-average wet winters. To improve process knowledge, a dense monitoring network consisting of rainfall gauges, meteorological stations and soil moisture plots was installed along a steep climatic gradient in the Jordan Valley region. Ten-minute soil moisture dynamics of two entire years were modelled by Hydrus-1D whose parameters were calibrated with the help of the Shuffled Complex Evolution algorithm. The scrutinized model was applied to four locations with entirely different soil depth and annual rainfall. During high intensity rainfall events, saturation of deep soil layers was observed for several hours. The continuously modelled water balance yielded percolation pulses that depended on rainfall amounts and occurred simultaneously to a cooling of karst groundwater in a nearby groundwater well. Overall, a strong correlation between the magnitude of deep percolation and soil depth was observed. When the model was applied to a 40-year time series of rainfall data, a mean annual percolation fraction of 40% resulted. This value varied by up to 30% between years with similar (average) rainfall but different rainfall distribution. Here the length of dry spells between single recharge events was one important factor. Percolation fraction of exceptional wet years reached up to 69% of rainfall while for very dry years no percolation was modelled at all. A focused view on the unsaturated soil zone in areas with highly variable annual rainfall can provide valuable insights into recharge heterogeneity under Mediterranean and semi-arid climates.

  18. A 25 ky BP record of Himalayan aridity using muscovite and clays as proxy climate indicators

    Digital Repository Service at National Institute of Oceanography (India)

    Gujar, A.R.; Chauhan, O.S.

    stream_size 18577 stream_content_type text/plain stream_name Giornale_Geol_61_115.pdf.txt stream_source_info Giornale_Geol_61_115.pdf.txt Content-Encoding UTF-8 Content-Type text/plain; charset=UTF-8 (iiomule di Geologia... regulated by thc climatic varia- bility of the region. Also, accumulation of muscovite and clays in a depositional basin dcpends: ( I ) on the magnitude of supply from the hinterland sources, and (2) prevalent en- vironment of deposition regulatcd by energy...

  19. Community responses to extreme climatic conditions

    Directory of Open Access Journals (Sweden)

    Frédéric JIGUET, Lluis BROTONS, Vincent DEVICTOR

    2011-06-01

    Full Text Available Species assemblages and natural communities are increasingly impacted by changes in the frequency and severity of extreme climatic events. Here we propose a brief overview of expected and demonstrated direct and indirect impacts of extreme events on animal communities. We show that differential impacts on basic biological parameters of individual species can lead to strong changes in community composition and structure with the potential to considerably modify the functional traits of the community. Sudden disequilibria have even been shown to induce irreversible shifts in marine ecosystems, while cascade effects on various taxonomic groups have been highlighted in Mediterranean forests. Indirect effects of extreme climatic events are expected when event-induced habitat changes (e.g. soil stability, vegetation composition, water flows altered by droughts, floods or hurricanes have differential consequences on species assembled within the communities. Moreover, in increasing the amplitude of trophic mismatches, extreme events are likely to turn many systems into ecological traps under climate change. Finally, we propose a focus on the potential impacts of an extreme heat wave on local assemblages as an empirical case study, analysing monitoring data on breeding birds collected in France. In this example, we show that despite specific populations were differently affected by local temperature anomalies, communities seem to be unaffected by a sudden heat wave. These results suggest that communities are tracking climate change at the highest possible rate [Current Zoology 57 (3: 406–413, 2011].

  20. Community responses to extreme climatic conditions

    Institute of Scientific and Technical Information of China (English)

    Frédéric JIGUET; Lluis BROTONS; Vincent DEVICTOR

    2011-01-01

    Species assemblages and natural communities are increasingly impacted by changes in the frequency and severity of extreme climatic events. Here we propose a brief overview of expected and demonstrated direct and indirect impacts of extreme events on animal communities. We show that differential impacts on basic biological parameters of individual species can lead to strong changes in community composition and structure with the potential to considerably modify the functional traits of the community. Sudden disequilibria have even been shown to induce irreversible shifts in marine ecosystems, while cascade effects on various taxonomic groups have been highlighted in Mediterranean forests. Indirect effects of extreme climatic events are expected when event-induced habitat changes (e.g. Soil stability, vegetation composition, water flows altered by droughts, floods or hurricanes) have differential consequences on species assembled within the communities. Moreover, in increasing the amplitude of trophic mismatches, extreme events are likely to turn many systems into ecological traps under climate change. Finally, we propose a focus on the potential impacts of an extreme heat wave on local assemblages as an empirical case study, analysing monitoring data on breeding birds collected in France. In this example, we show that despite specific populations were differently affected by local temperature anomalies, communities seem to be unaffected by a sudden heat wave. These results suggest that communities are tracking climate change at the highest possible rate.

  1. Geochemical and isotopic studies of unsaturated zone moisture and recharge processes in semi-arid conditions

    International Nuclear Information System (INIS)

    Against the background of recent droughts in the Sahel and the overexploitation of scarce water resources, new and improved techniques for recharge estimation in arid lands are now needed. Results have been obtained from the Butana area of Sudan where rainfall is presently well below 200 mm a-1. Profiles of the unsaturated zone moisture were analysed for solutes and oxygen (δ18O) and hydrogen (δD) isotope ratios to estimate the extent of current recharge. Chloride concentrations were compared with those from rainfall inputs and the ratio used to estimate long term recharge values. Direct recharge proved to be below 1 mm a-1 and the unsaturated zone (25 m approx) contained around 2000 years storage. Isotopic profiles indicated that in some areas discharge from the water table was occurring. Within the Butana region of Sudan, therefore, current recharge rates in interfluve areas are effectively zero. Lateral recharge is however occurring, based on the presence of tritium, from the wadi systems. This forms the only replenishable resource which has been successfully exploited by traditional means, although under stress in the present dry period. The River Nile can be shown from isotopic results to recharge laterally some 10 km; but the deeper resources elsewhere are palaeowaters replenished during Holocene wet periods (6000-8000 BP). 2 refs, 6 figs

  2. Biogeochemical evolution of sulfide ore mine tailings profiles under semi-arid climate

    Science.gov (United States)

    Chorover, J.

    2014-12-01

    Mining represents a principal form of earth surface disturbance in the anthropocene. Weathering reactions that ensue following tailings deposition are strongly affected by climatic forcing and tailings composition, and these also affect the weathering-induced transformations of the associated mineral assemblages and metal(loid) contaminants. The presence or absence of plants and associated microbiota can have a profound influence on these weathering trajectories. We employed field, laboratory and modeling approaches to resolve the impact of (bio)geochemical weathering reactions on the transformation of mine tailings parent materials into soil over the time following mining cessation. Using controlled experiments, we have evaluated the impacts of plants and associated rhizosphere microbiota on these reactions, hydrologic fluxes, and the molecular speciation of mining derived contaminants. Plant establishment is shown to alter site ecohydrology and biogeochemical weathering processes leading to distinctly different weathering products and patterns.

  3. Modeling the Impact of Climate and Population Change Scenarios in a Semi-arid Aquifer

    Science.gov (United States)

    Neff, K.; Mallakpour, I.; Maddock, T.; Meixner, T.

    2011-12-01

    The Upper San Pedro River in Southern Arizona has been modeled using MODFLOW several times, most recently by Goode and Maddock (2000) and Pool and Dickinson (2006). It is the last free-flowing river in Arizona and its riparian area serves as habitat for migrating birds and several endangered native species. Understanding how the river will respond to future climate and population change is critical for the successful management of this resource. In the current model, we improve upon previous models by adding a third season to represent the summer monsoon rains, changing the model domain to include only the basin fill in order to minimize error, and using newer MODFLOW packages such as Streamflow Routing (SFR) to more accurately model the riparian system. GMS is used to produce the initial MODFLOW files. Once the new regional model was developed, we changed inputs to the model in order to observe the effects of changes in regional precipitation and temperature due to climate change, as well as changes in pumping for human use, on the aquifer and river. The challenge of adapting an older model to use new data and technology is valuable because it will improve model performance and provide better information to water resources decision-makers in the basin, who are faced with potential increases in population and thus municipal water demand. The new regional model is also intended to be coupled in the future with a stream network flood routing model to reflect the role of flood-pulse recharge on groundwater and streamflow levels.

  4. Agroclimatic conditions in Europe under climate change

    Czech Academy of Sciences Publication Activity Database

    Trnka, Miroslav; Olesen, J. E.; Kersebaum, K. C.; Skjelvag, A. O.; Eitzinger, J.; Seguin, B.; Peltonen-Sainio, P.; Rotter, R.; Iglesias, A.; Orlandini, S.; Dubrovský, Martin; Hlavinka, P.; Balek, J.; Eckersten, H.; Cloppet, E.; Calanca, P.; Vucetic, V.; Nejedlík, P.; Kumar, S.; Lalic, B.; Mestre, A.; Rossi, F.; Kozyra, J.; Alexandrov, V.; Semerádová, D.; Žalud, Z.

    2011-01-01

    Roč. 17, č. 7 (2011), s. 2298-2318. ISSN 1354-1013 R&D Projects: GA MŠk(CZ) ED1.1.00/02.0073 Institutional research plan: CEZ:AV0Z60870520; CEZ:AV0Z30420517 Keywords : agroclimatic extremes * agroclimatic index * climate - change impacts * crop production * environmental zones Subject RIV: EH - Ecology, Behaviour Impact factor: 6.862, year: 2011

  5. Spatial distribution and comparison of aridity indices in Extremadura, southwestern Spain

    Science.gov (United States)

    Moral, Francisco J.; Rebollo, Francisco J.; Paniagua, Luis L.; García-Martín, Abelardo; Honorio, Fulgencio

    2015-09-01

    In semi-arid lands with warm climates, aridity is a real hazard, with the threat of desertification because of greater precipitation variability and prolonged droughts. Aridity indices can be used to identify areas prone to desertification. The present study aimed to analyse the spatial distribution of aridity in Extremadura, southwestern Spain, using three indices: the De Martonne aridity index (I DM), the Pinna combinative index (I P), and the Food and Agriculture Organization (FAO) aridity index (I F). Temperature, precipitation, and evapotranspiration data from 90 weather stations located throughout Extremadura and 27 along boundaries with at least 30-year length (within the 1980-2011 period) were used to compute each index at each station. The statistical properties of each aridity index were assessed, and later, they were mapped by means of an integrated geographic information system (GIS) and a multivariate geostatistical (regression-kriging) algorithm in which exhaustive secondary information on elevation was incorporated. Annual and seasonal I DM and I F, and annual I P-kriged maps were generated. According to annual I DM, the semi-arid and Mediterranean conditions are predominant in the region, covering about 70 % of the territory, while about 94 % of the areas are classified as dry and semi-dry Mediterranean based on annual I P and about 86 % are classified as semi-arid and dry categories based on annual I F. The most vulnerable to aridity are the natural regions located to the west, the south, and the southeast of Extremadura, especially during summer, when arid conditions are found across the region. Although the three aridity indices were highly correlated, displaying similar spatial patterns, I DM was preferred because it can better discriminate different climate conditions in Extremadura.

  6. Land Cover Land Use change and soil organic carbon under climate variability in the semi-arid West African Sahel (1960-2050)

    Science.gov (United States)

    Dieye, Amadou M.

    Land Cover Land Use (LCLU) change affects land surface processes recognized to influence climate change at local, national and global levels. Soil organic carbon is a key component for the functioning of agro-ecosystems and has a direct effect on the physical, chemical and biological characteristics of the soil. The capacity to model and project LCLU change is of considerable interest for mitigation and adaptation measures in response to climate change. A combination of remote sensing analyses, qualitative social survey techniques, and biogeochemical modeling was used to study the relationships between climate change, LCLU change and soil organic carbon in the semi-arid rural zone of Senegal between 1960 and 2050. For this purpose, four research hypotheses were addressed. This research aims to contribute to an understanding of future land cover land use change in the semi-arid West African Sahel with respect to climate variability and human activities. Its findings may provide insights to enable policy makers at local to national levels to formulate environmentally and economically adapted policy decisions. This dissertation research has to date resulted in two published and one submitted paper.

  7. Assessment of climate change impacts on watershed in cold-arid region: an integrated multi-GCM-based stochastic weather generator and stepwise cluster analysis method

    Science.gov (United States)

    Zhuang, X. W.; Li, Y. P.; Huang, G. H.; Liu, J.

    2016-07-01

    An integrated multi-GCM-based stochastic weather generator and stepwise cluster analysis (MGCM-SWG-SCA) method is developed, through incorporating multiple global climate models (MGCM), stochastic weather generator (SWG), and stepwise-clustered hydrological model (SCHM) within a general framework. MGCM-SWG-SCA can investigate uncertainties of projected climate changes as well as create watershed-scale climate projections from large-scale variables. It can also assess climate change impacts on hydrological processes and capture nonlinear relationship between input variables and outputs in watershed systems. MGCM-SWG-SCA is then applied to the Kaidu watershed with cold-arid characteristics in the Xinjiang Uyghur Autonomous Region of northwest China, for demonstrating its efficiency. Results reveal that the variability of streamflow is mainly affected by (1) temperature change during spring, (2) precipitation change during winter, and (3) both temperature and precipitation changes in summer and autumn. Results also disclose that: (1) the projected minimum and maximum temperatures and precipitation from MGCM change with seasons in different ways; (2) various climate change projections can reproduce the seasonal variability of watershed-scale climate series; (3) SCHM can simulate daily streamflow with a satisfactory degree, and a significant increasing trend of streamflow is indicated from future (2015-2035) to validation (2006-2011) periods; (4) the streamflow can vary under different climate change projections. The findings can be explained that, for the Kaidu watershed located in the cold-arid region, glacier melt is mainly related to temperature changes and precipitation changes can directly cause the variability of streamflow.

  8. Assessment of climate change impacts on watershed in cold-arid region: an integrated multi-GCM-based stochastic weather generator and stepwise cluster analysis method

    Science.gov (United States)

    Zhuang, X. W.; Li, Y. P.; Huang, G. H.; Liu, J.

    2015-12-01

    An integrated multi-GCM-based stochastic weather generator and stepwise cluster analysis (MGCM-SWG-SCA) method is developed, through incorporating multiple global climate models (MGCM), stochastic weather generator (SWG), and stepwise-clustered hydrological model (SCHM) within a general framework. MGCM-SWG-SCA can investigate uncertainties of projected climate changes as well as create watershed-scale climate projections from large-scale variables. It can also assess climate change impacts on hydrological processes and capture nonlinear relationship between input variables and outputs in watershed systems. MGCM-SWG-SCA is then applied to the Kaidu watershed with cold-arid characteristics in the Xinjiang Uyghur Autonomous Region of northwest China, for demonstrating its efficiency. Results reveal that the variability of streamflow is mainly affected by (1) temperature change during spring, (2) precipitation change during winter, and (3) both temperature and precipitation changes in summer and autumn. Results also disclose that: (1) the projected minimum and maximum temperatures and precipitation from MGCM change with seasons in different ways; (2) various climate change projections can reproduce the seasonal variability of watershed-scale climate series; (3) SCHM can simulate daily streamflow with a satisfactory degree, and a significant increasing trend of streamflow is indicated from future (2015-2035) to validation (2006-2011) periods; (4) the streamflow can vary under different climate change projections. The findings can be explained that, for the Kaidu watershed located in the cold-arid region, glacier melt is mainly related to temperature changes and precipitation changes can directly cause the variability of streamflow.

  9. Re-use of wastewater for a sustainable forest production and climate change mitigation under arid environments

    Directory of Open Access Journals (Sweden)

    Maria Cristina Monteverdi

    2014-06-01

    Full Text Available 800x600 Over the last decades biotic and abiotic constrains together with human actions are determining a substantial environmental pressure, particularly in dry lands as the south of the Mediterranean region. From very long time, indeed, simultaneous drivers such as demographic growth, climate change and socio-economic factors are weakening the previous homeostasis between human needs and natural resources on the regional scale.Resulting pressures are determining environmental degradation and increase of desertification risk for the arid and semiarid lands. Water quality and availability are both crucial points limiting people well-being and livelihoods in the same context. Scarcity of fresh water and heavy and mismanaged production of wastewater are the main factors affecting water resources. Increasing pollution of soil and ground waters reduces the possibility of sustainable development of local communities with relevant social consequences. The FAO's supporting program in north Africa aims to: a develop new and cheaper phytotechnologies (e.g. constructed wetland system; innovative treatment system for reuse of waste water for fertigation; b treat wastewater for water quality protection; c promote land recovery by means of sustainable multipurpose forestry; d adopt bioengineering interventions to stop slopes erosion and protect urban, and semi-urban infrastructures; e create pilot demonstrative areas to test multi-purpose sustainable agroforestry systems. Within this frame, an integrated approach was designed to promote innovative sustainable water management and multipurpose forestry, in order to mitigate the effects of climate change, promote land recovery, and improve the livelihoods of local population. The present paper aims to provide an overview of the FAO project GCP/RAB/013/ITA. Particularly, two pilot studies are shown and discussed. Normal 0 14 false false false IT X-NONE X-NONE MicrosoftInternetExplorer4 /* Style Definitions

  10. Tropical Warm Semi-Arid Regions Expanding Over Temperate Latitudes In The Projected 21st Century

    Science.gov (United States)

    Rajaud, A.; de Noblet, N. I.

    2015-12-01

    Two billion people today live in drylands, where extreme climatic conditions prevail, and natural resources are limited. Drylands are expected to expand under several scenarios of climatic change. However, relevant adaptation strategies need to account for the aridity level: it conditions the equilibrium tree-cover density, ranging from deserts (hyper-arid) to dense savannas (sub-humid). Here we focus on the evolution of climatically defined warm semi-arid areas, where low-tree density covers can be maintained. We study the global repartition of these regions in the future and the bioclimatic shifts involved. We adopted a bioclimatological approach based on the Köppen climate classification. The warm semi-arid class is characterized by mean annual temperatures over 18°C and a rainfall-limitation criterion. A multi-model ensemble of CMIP5 projections for three representative concentration pathways was selected to analyze future conditions. The classification was first applied to the start, middle and end of the 20th and 21st centuries, in order to localize past and future warm semi-arid regions. Then, time-series for the classification were built to characterize trends and variability in the evolution of those regions. According to the CRU datasets, global expansion of the warm semi-arid area has already started (~+13%), following the global warming trend since the 1900s. This will continue according to all projections, most significantly so outside the tropical belt. Under the "business as usual" scenario, the global warm semi-arid area will increase by 30% and expand 12° poleward in the Northern Hemisphere, according to the multi-model mean. Drying drives the conversion from equatorial sub-humid conditions. Beyond 30° of latitude, cold semi-arid conditions become warm semi-arid through warming, and temperate conditions through combined warming and drying processes. Those various transitions may have drastic but also very distinct ecological and sociological

  11. A coupled Bayesian and fault tree methodology to assess future groundwater conditions in light of climate change

    Directory of Open Access Journals (Sweden)

    J. J. Huang

    2014-08-01

    Full Text Available Maintaining acceptable groundwater levels, particularly in arid areas, while protecting ecosystems, are key measures against desertification. Due to complicated hydrological processes and their inherent uncertainties, investigations of groundwater recharge conditions are challenging, particularly in arid areas under climate changing conditions. To assist planning to protect against desertification, a fault tree methodology, in conjunction with fuzzy logic and Bayesian data mining, are applied to Minqin Oasis, a highly vulnerable regime in northern China. A set of risk factors is employed within the fault tree framework, with fuzzy logic translating qualitative risk data into probabilities. Bayesian data mining is used to quantify the contribution of each risk factor to the final aggregated risk. The implications of both historical and future climate trends are employed for temperature, precipitation and potential evapotranspiration (PET to assess water table changes under various future scenarios. The findings indicate that water table levels will continue to drop at the rate of 0.6 m yr−1 in the future when climatic effects alone are considered, if agricultural and industrial production capacity remain at 2004 levels.

  12. Effects of Maghnian bentonite on physical properties of sandy soils under semi-arid Mediterranean climate.

    Science.gov (United States)

    Benkhelifa, M; Belkhodja, M; Daoud, Y; Tessier, D

    2008-01-01

    This research has for object to study the influence of clay addition, i.e., Maghnian bentonite, like deposit clay, in the physical properties of sandy materials from Mostaganem plateau (North-West Algeria) submitted to salinity and sodicity. The first result was to show that the clay content changes drastically the physical properties of clay-sand mixtures. Important differences were observed as a function of the sand particle size distribution. At given clay content, the saturated Hydraulic Conductivity (HCs) was lower when the sand size was small and spread. For the coarse sand the salinity was maintained, even for high clay contents, a significant hydraulic conductivity. One of the main characteristics of Maghnia clay is the presence of calcium carbonates in the natural material. In comparison to that of Mostaganem clay of other deposit, it appears less sensitive to sodicity. An important aspect is the initial state of the clay when used in addition to sands, i.e., disturbance, conditions of preparation of sand clay mixtures and presence of associated components such as carbonates. Maghnia clay appeared to be adapted to the improvement of sandy soils, not because its mineralogical characteristics, but for its natural cationic form and obviously the presence of calcite in it. PMID:18819588

  13. Impact of the use of a hybrid turbine inlet air cooling system in arid climates

    International Nuclear Information System (INIS)

    Graphical abstract: Cooling the air entering the compressor section of a gas turbine is a proven method of increasing turbine power output, especially during peak summer demand, and it is increasingly being used in powerplants worldwide. Two turbine inlet air cooling (TIAC) systems are widely used: evaporative cooling and mechanical chilling. In this work, the prospects of using a hybrid turbine inlet air cooling (TIAC) system are investigated. The hybrid system consists of mechanical chilling followed by evaporative cooling. Such a system is capable of achieving a significant reduction in inlet air temperature that satisfies desired power output levels, while consuming less power than conventional mechanical chilling and less water than conventional evaporative cooling, thus combining the benefits of both approaches. Two hybrid system configurations are studied. In the first configuration, the first stage of the system uses water-cooled chillers that are coupled with dry coolers such that the condenser cooling water remains in a closed loop. In the second configuration, the first stage of the system uses water-cooled chillers but with conventional cooling towers. An assessment of the performance and economics of those two configurations is made by comparing them to conventional mechanical chilling and using realistic data. It was found that the TIAC systems are capable of boosting the power output of the gas turbine by 10% or more (of the power output of the ISO conditions). The cost operation analysis shows clearly the hybrid TIAC method with wet cooling has the advantage over the other methods and It would be profitable to install it in the new gas turbine power plants. The figure below shows a comparison of the water consumption for the three different cases. - Highlights: • New hybrid system for the turbine inlet air cooling is studied. • Hybrid system of mechanical chilling followed by evaporative cooling is used. • Hybrid turbine inlet air cooling

  14. Modeling groundwater quality in an arid agricultural environment in the face of an uncertain climate: the case of Mewat District, India

    Science.gov (United States)

    Weber, M. C.; Ward, A. S.; Muste, M.

    2014-12-01

    The salinization of groundwater resources is a widespread problem in arid agricultural environments. In Mewat District (Haryana, India), groundwater salinity has rendered much of the accessible supply unfit for human consumption or agriculture. Historically, this closed basin retained fresh pockets of water at the foothills of the Aravalli Hills, where monsoonal precipitation runoff from the mountains was recharged through infiltration or facilitated by man-made structures. To date, an increasing number of pumps supply the region with fresh water for consumption and agriculture leading to shrinking the freshwater zone at an accelerated pace. The potential for increased human consumption corroborated with the effects of climate change bring uncertainty about the future of water security for the Mewat communities, most of them critically bound to the existence of local water. This study addresses the sustainability of the freshwater supply under a range of land interventions and climate scenarios, using a 2-D groundwater flow and transport model. Our results quantify potential futures for this arid, groundwater-dependent location, using numerical groundwater modeling to quantify interactions between human water use, infrastructure, and climate. Outcomes of this modeling study will inform an NGO active in the area on sustainable management of groundwater resources.

  15. Future Risks of Pest Species under Changing Climatic Conditions.

    Science.gov (United States)

    Biber-Freudenberger, Lisa; Ziemacki, Jasmin; Tonnang, Henri E Z; Borgemeister, Christian

    2016-01-01

    Most agricultural pests are poikilothermic species expected to respond to climate change. Currently, they are a tremendous burden because of the high losses they inflict on crops and livestock. Smallholder farmers in developing countries of Africa are likely to suffer more under these changes than farmers in the developed world because more severe climatic changes are projected in these areas. African countries further have a lower ability to cope with impacts of climate change through the lack of suitable adapted management strategies and financial constraints. In this study we are predicting current and future habitat suitability under changing climatic conditions for Tuta absoluta, Ceratitis cosyra, and Bactrocera invadens, three important insect pests that are common across some parts of Africa and responsible for immense agricultural losses. We use presence records from different sources and bioclimatic variables to predict their habitat suitability using the maximum entropy modelling approach. We find that habitat suitability for B. invadens, C. cosyra and T. absoluta is partially increasing across the continent, especially in those areas already overlapping with or close to most suitable sites under current climate conditions. Assuming a habitat suitability at three different threshold levels we assessed where each species is likely to be present under future climatic conditions and if this is likely to have an impact on productive agricultural areas. Our results can be used by African policy makers, extensionists and farmers for agricultural adaptation measures to cope with the impacts of climate change. PMID:27054718

  16. Concentrations and Fractionation of Carbon, Iron, Sulfur, Nitrogen and Phosphorus in Mangrove Sediments Along an Intertidal Gradient (Semi-Arid Climate, New Caledonia)

    OpenAIRE

    Jonathan Deborde; Cyril Marchand; Nathalie Molnar; Luc Della Patrona; Tarik Meziane

    2015-01-01

    In mangrove ecosystems, strong reciprocal interactions exist between plant and substrate. Under semi-arid climate, Rhizophora spp. are usually predominant, colonizing the seashore, and Avicennia marina develops at the edge of salt-flats, which is the highest zone in the intertidal range. Along this zonation, distribution and speciation of C, Fe, S, N, and P in sediments and pore-waters were investigated. From the land-side to the sea-side of the mangrove, sediments were characterized by I/ in...

  17. Local facilitation, bistability and transitions in arid ecosystems

    NARCIS (Netherlands)

    Kefi, S.; Rietkerk, M.; Baalen, van M.; Loreau, M.

    2007-01-01

    Arid ecosystems are liable to undergo sudden discontinuous transitions from a vegetated to a desert state as a result of human pressure and climate change. A predictive framework about the conditions under which such transitions occur is lacking. Here, we derive and analyze a general model describin

  18. Groundwater prospecting, drilling and well construction in hard rocks in semi-arid regions: an overview

    OpenAIRE

    Chambel, António

    2012-01-01

    In semi-arid and arid areas rock weathering is normally much less deep that in rainy areas. So, rocks tend to be more near the topographic surface. These climatic conditions also generate much less vegetation, which in all the cases clearly favours a direct observation of rock condition, fracturing or weathering. By other side, aquifers in hard rocks present specificities in relation to water presence and movement that implies a different approach when dealing with groundwater prospecting....

  19. Innovative Air Conditioning and Climate Control

    Science.gov (United States)

    Graf, John

    2015-01-01

    NASA needed to develop a desiccant wheel based humidity removal system to enable the long term testing of the Orion CO2 scrubber on the International Space Station. In the course of developing that system, we learned three things that are relevant to energy efficient air conditioning of office towers. NASA developed a conceptual design for a humidity removal system for an office tower environment. We are looking for interested partners to prototype and field test this concept.

  20. Low Energy Air Conditioning for Hot Climates

    OpenAIRE

    Almutairi, Hamad Hhn

    2012-01-01

    Fossil fuels are the major sources of electrical power generation in the world. Among all fossil fuels, oil is considered as the most sought-after fuel. The burden on countries that provide subsidized electricity produced from oil-fired power plants is noteworthy. Kuwait is a notable example of these countries. Electricity in Kuwait is heavily consumed by residential air conditioning, which comprises 60% of the total electricity generated at peak times on a hot summer day. From this perspecti...

  1. To enhance the cooling comfort condition in home by water spray upon the roof in hot arid region experimental work

    International Nuclear Information System (INIS)

    Fossil fuel shortages have been in recent years a critical problem in the world and are likely to be continued. A major part of consumed energy nowadays is used to thermally control building environment where solar radiation has a major contribution, specially in Iraq and other hot arid region where most of the day in the year are sunny. Baghdad, which is considered a typical place with this extreme climate, is chosen, in this study. This work deals with the possibility of the reducing energy consumption in building by blocking or eliminate the effect of direct solar radiation in summer season which the cooling is dominate in Iraq. It is especially important to minimize the effect of solar radiation incident upon the roof surface, which is focusing about it in this study. The roof surface most exposed to solar radiation and most of the solar gain absorbed by roof is transmitted down to the inside space. In this study built a system which spry water upon the external surface consist of net work piping system, control valves, spry nozzles, thermocouples sensor and digital temperature indicators. The study has been done in order to reduce the cooling load in living room. Reducing the heat transfer through the roof by using water spry roof system (WSRS) in Iraq's houses which reduced the heat transmission to the inside space about 96%. The result of this study shows good indication to use this method, to reduce the energy transmission. i./e. the energy transmission to inside living space through roof is about 4% only.(Author)

  2. Recycling of quartz-poor/lithic-rich foreland-basin sediments in arid climate (Euphrates-Tigris-Karun river system)

    Science.gov (United States)

    Garzanti, Eduardo; Juboury, Ali Ismail Al; Zoleikhaei, Yousef; Vermeesch, Pieter; Hamzah Abdulhussein Jotheri, Jaafar; Akkoca, Dicle Bal; Allen, Mark; Andò, Sergio; Limonta, Mara; Padoan, Marta; Resentini, Alberto; Vezzoli, Giovanni

    2016-04-01

    In this detailed petrological analysis of a large source-to-sink sediment-routing system (catchment area > 1 million km2) we document its several peculiarities, and illustrate a rich petrographic and heavy-mineral dataset integrated by bulk-sediment geochemistry and detrital-zircon U-Pb geochronological data that widens the spectrum of compositions generally assumed as paradigmatic for orogenic settings. We test traditional versus upgraded sedimentary-petrology models in the endeavor to derive a more refined conceptual model of reference, in order to enhance the power of provenance analysis but also to define its limitations and understand which secret of nature is likely to remain beyond reach in our efforts to reconstruct orogenic landscapes of the past. Sands derived from the Zagros-Southeast Anatolian fold-thrust belt contain an abundance of lithic grains derived not only first-cycle from carbonates, cherts, mudrocks, arc volcanics, and obducted mantle serpentinites representing the exposed shallow structural level of the orogen, but also recycled from Neogene molassic strata exposed in the foothills. Quartz, K-feldspar and mica are equally scarce in first-cycle and recycled sediments. This quartz-poor petrographic signature, characterizing the broad undissected tectonic domain of the Anatolia-Iranian plateau, is markedly distinct from that of sands shed by highly elevated and dissected collision orogens of the same mountain system such as the Himalaya or the Alps. Arid climate in the region allows full preservation of chemically unstable grains including carbonate and mafic/ultramafic rock fragments even through more than a single sedimentary cycle. Also, it reduces transport capacity of fluvial systems, which dump most of their load in Mesopotamian marshlands upstream of the Arabian/Persian Gulf allochemical carbonate factory. Quartz-poor orogenic sediments from the Zagros-Southeast Anatolian range mix with quartz-rich recycled sands ultimately derived from

  3. The Sand Seas of northern China: Important sinks and sources of global sediment fluxes and their changing roles during different climate conditions of Late Quaternary

    Science.gov (United States)

    Yang, X.

    2014-12-01

    Although the occurrence of aeolian sands in sedimentary sequences has been widely used as indicators of desert formation or proxies of desert climate, one should be aware that accumulation of aeolian sands does occur along river channels, in lake shores not necessarily associated with arid environment. Our ongoing geomorphological and paleoenvironmental studies in the deserts of northern China reconfirm that formation of sand seas is dependent on not only erodibility (arising from bare surface due to aridity) and wind power but more importantly sand availability related to sediment cycles under interactions between fluvial, lacustrine and aeolian processes. Here we present our ongoing geomorphological and paleoclimatic research on the Late Quaternary landscape and climatic changes in the Taklamkan Desert of northwestern China, the largest sand sea of China in arid zone, and in the Hunshandake Sandy Land at the east part of the Asian mid-latitude desert belt under semiarid climate. We find out that the occurrence of tall sand dunes in the over 300,000 km2 large Taklamakan Sand Sea is closely related to the sites of intensive fluvial sedimentation and convergence zone of surface winds. In the case of Hunshandake, the dunes (although much smaller) mainly occur along the shorelines of the former lake basins, and sediment sources are generally limited because of open hydrological systems in the south and east portions of this desert. The sedimentological and geomorphological records suggest that the climate has changed between arid and less-arid conditions in both of these deserts during Late Quaternary. Under wetter conditions the Taklamakan acts as an important sink of sediments brought by rivers with headwaters in the Tibetan Plateau and Tianshan, while under more arid conditions it acts as an important global sediment source whose dust is transported not only to East Asia and Pacific but also to Greenland ice via westerlies. The Hunshandake has the same pattern of

  4. Impact of treated wastewater reuse and floods on water quality and fish health within a water reservoir in an arid climate.

    Science.gov (United States)

    Zaibel, Inbal; Zilberg, Dina; Groisman, Ludmila; Arnon, Shai

    2016-07-15

    Treated wastewater (TWW) reuse for agricultural irrigation is a well-established approach to coping with water shortages in semi-arid and arid environments. Recently, additional uses of TWW have emerged, including streamflow augmentation and aquatic ecosystem restoration. The purpose of the current study was to evaluate the water quality and fish health, in an artificial reservoir located in an arid climate (the Yeruham Reservoir, Israel), which regularly receives TWW and sporadic winter floods. The temporal distribution of water levels, nutrients and organic micropollutants (OMPs) were measured during the years 2013-2014. OMPs were also measured in sediment and fish tissues. Finally, the status of fish health was evaluated by histopathology. Water levels and quality were mainly influenced by seasonal processes such as floods and evaporation, and not by the discharge of TWW. Out of 16 tested OMPs, estrone, carbamazepine, diclofenac and bezafibrate were found in the reservoir water, but mostly at concentrations below the predicted no-effect concentration (PNEC) for fish. Concentrations of PCBs and dioxins in fish muscle and liver were much lower than the EU maximal permitted concentrations, and similar to concentrations that were found in food fish in Israel and Europe. In the histopathological analysis, there were no evident tissue abnormalities, and low to moderate infection levels of fish parasites were recorded. The results from the Yeruham Reservoir demonstrated a unique model for the mixture effect between TWW reuse and natural floods to support a unique stable and thriving ecosystem in a water reservoir located in an arid region. This type of reservoir can be widely used for recreation, education, and the social and economic development of a rural environment, such as has occurred in the Yeruham region. PMID:27065446

  5. Assessment of adaptability of zebu cattle (Bos indicus) breeds in two different climatic conditions: using cytogenetic techniques on genome integrity.

    Science.gov (United States)

    Kumar, Anil; Waiz, Syma Ashraf; Sridhar Goud, T; Tonk, R K; Grewal, Anita; Singh, S V; Yadav, B R; Upadhyay, R C

    2016-06-01

    The aim of this study was to evaluate the genome integrity so as to assess the adaptability of three breeds of indigenous cattle reared under arid and semi-arid regions of Rajasthan (Bikaner) and Haryana (Karnal) India. The cattle were of homogenous group (same age and sex) of indigenous breeds viz. Sahiwal, Tharparkar and Kankrej. A total of 100 animals were selected for this study from both climatic conditions. The sister chromatid exchanges (SCE's), chromosomal gaps and chromatid breaks were observed in metaphase plates of chromosome preparations obtained from in vitro culture of peripheral blood lymphocytes. The mean number of breaks and gaps in Sahiwal and Tharparkar of semi-arid zone were 8.56 ± 3.16, 6.4 ± 3.39 and 8.72 ± 2.04, 3.52 ± 6.29, respectively. Similarly, the mean number of breaks and gaps in Tharparkar and Kankrej cattle of arid zone were 5.26 ± 1.76, 2.74 ± 1.76 and 5.24 ± 1.84, 2.5 ± 1.26, respectively. The frequency of SCEs in chromosomes was found significantly higher (P P P > 0.05) was observed in the same zone. The analysis of frequency of CAs and SCEs revealed significant effects of environmental conditions on the genome integrity of animals, thereby indicating an association with their adaptability. PMID:26476524

  6. Comparison of SVAT models for simulating and optimizing deficit irrigation systems in arid and semi-arid countries under climate variability

    Science.gov (United States)

    Kloss, Sebastian; Schuetze, Niels; Schmitz, Gerd H.

    2010-05-01

    The strong competition for fresh water in order to fulfill the increased demand for food worldwide has led to a renewed interest in techniques to improve water use efficiency (WUE) such as controlled deficit irrigation. Furthermore, as the implementation of crop models into complex decision support systems becomes more and more common, it is imperative to reliably predict the WUE as ratio of water consumption and yield. The objective of this paper is the assessment of the problems the crop models - such as FAO-33, DAISY, and APSIM in this study - face when maximizing the WUE. We applied these crop models for calculating the risk in yield reduction in view of different sources of uncertainty (e.g. climate) employing a stochastic framework for decision support for the planning of water supply in irrigation. The stochastic framework consists of: (i) a weather generator for simulating regional impacts of climate change; (ii) a new tailor-made evolutionary optimization algorithm for optimal irrigation scheduling with limited water supply; and (iii) the above mentioned models for simulating water transport and crop growth in a sound manner. The results present stochastic crop water production functions (SCWPF) for different crops which can be used as basic tools for assessing the impact of climate variability on the risk for the potential yield. Case studies from India, Oman, Malawi, and France are presented to assess the differences in modeling water stress and yield response for the different crop models.

  7. Estrus synchronization and fixed-time artificial insemination in sheep under field conditions of a semi-arid tropical region.

    Science.gov (United States)

    De, Kalyan; Kumar, Davendra; Sethi, Debabrata; Gulyani, Rajiv; Naqvi, Syed Mohammed Khursheed

    2015-02-01

    A study was conducted to assess the success of estrus synchronization and fixed-time artificial insemination (FTAI) in sheep under field conditions of a semi-arid tropical region. A total of 471 ewes belonging to 17 farmers of four villages in Tonk district of Rajasthan (Jelmiya, Dhani Jaisinghpura, Tantiya and Bheepur) were synchronized for estrus during the years 2011 and 2012. Synchronization of estrus was done by AVIKESIL-S, cost-effective intra-vaginal sponges developed by the Institute and eCG protocol. The sponges were kept in situ in the vagina for 12 days and 200 IU eCG (Folligon, Intervet) was administered intramuscularly at the time of sponge withdrawal on the 12th day. Fixed-time cervical insemination was performed twice in ewes exhibiting estrus (restlessness, shaking of tail, slightly swollen vulva, moist and reddish cervical external os), 48 and 56 h after sponge removal, using liquid chilled semen of Patanwadi/Malpura rams containing 100 million sperm per dose. The estrus response recorded was 79.4 % (374/471) and lambing rate was 60.42 % (226/374). It may be concluded from the encouraging results of the present study that FTAI can be used effectively to take advantage of both the genetic improvement and economic benefit that can be realized by the use of estrus synchronization in conjunction with artificial insemination (AI). PMID:25475009

  8. Changes in alpine plant growth under future climate conditions

    Directory of Open Access Journals (Sweden)

    A. Rammig

    2010-06-01

    Full Text Available Alpine shrub- and grasslands are shaped by extreme climatic conditions such as a long-lasting snow cover and a short vegetation period. Such ecosystems are expected to be highly sensitive to global environmental change. Prolonged growing seasons and shifts in temperature and precipitation are likely to affect plant phenology and growth. In a unique experiment, climatology and plant growth was monitored for almost a decade at 17 snow meteorological stations in different alpine regions along the Swiss Alps. Regression analyses revealed highly significant correlations between mean air temperature in May/June and snow melt out, onset of plant growth, and plant height. These correlations were used to project plant growth phenology for future climate conditions based on the gridded output of a set of regional climate models runs. Melt out and onset of growth were projected to occur on average 17 days earlier by the end of the century than in the control period from 1971–2000 under the future climate conditions of the low resolution climate model ensemble. Plant height and biomass production were expected to increase by 77% and 45%, respectively. The earlier melt out and onset of growth will probably cause a considerable shift towards higher growing plants and thus increased biomass. Our results represent the first quantitative and spatially explicit estimates of climate change impacts on future growing season length and the respective productivity of alpine plant communities in the Swiss Alps.

  9. Effect Of Climatic Conditions On Durability

    Directory of Open Access Journals (Sweden)

    Ibrahem M. Al Kiki

    2013-04-01

    Full Text Available Durability is one of the most important subjects in the soil stabilization. Since there is no specifications concerned the durability of lime stabilized soils, several factors were selected to show their effects on the durability, namely: wetting, drying, freezing, thawing and slaking.The effect of each one of the above factors as well as the combined effect of two or more factors, were studied on the volume change and soil strength and weight loss of soil samples stabilized with optimum lime content except the slaking test at which soil samples stabilized with different lime content.Tests results showed that the higher the lime content the lower the slaking effect, also its found the soil strength decreased when the period of immersion or freezing increased. The strength of the lime stabilized soils decreased when subjected to the cycles of wetting and drying or to the cycles freezing and thawing. However, the  combined effect of wetting, drying, freezing and thawing has a pronounced effect on reduction of the lime stabilized clayey soil. The worst condition recorded when lime stabilized soil undergo to freezing then drying then wetting which should be avoided in the field

  10. A remote sensing approach for estimating the location and rate of urban irrigation in semi-arid climates

    Science.gov (United States)

    Johnson, Tyler D.; Belitz, Kenneth

    2012-01-01

    Urban irrigation is an important component of the hydrologic cycle in many areas of the arid and semiarid western United States. This paper describes a new approach that uses readily available datasets to estimate the location and rate of urban irrigation. The approach provides a repeatable methodology at 1/3 km2 resolution across a large urbanized area (500 km2). For this study, Landsat Thematic Mapper satellite imagery, air photos, climatic records, and a land-use map were used to: (1) identify the fraction of irrigated landscaping in urban areas, and (2) estimate the monthly rate of irrigation being applied to those areas. The area chosen for this study was the San Fernando Valley in Southern California. Identifying irrigated areas involved the use of 29 satellite images, air photos, and a land-use map. The fraction of a pixel that consists of irrigated landscaping (Firr) was estimated using a linear-mixture model of two land-cover endmembers (selected pixels within a satellite image that represent a targeted land-cover). The two endmembers were impervious and fully-irrigated landscaping. In the San Fernando Valley, we used airport buildings, runways, and pavement to represent the impervious endmember; golf courses and parks were used to represent the fully irrigated endmember. The average Firr using all 29 satellite scenes was 44%. Firr calculated from hand-digitizing using air photos for 13 randomly selected single-family-residential neighborhoods showed similar results (42%). Estimating the rate of irrigation required identification of a third endmember: areas that consisted of urban vegetation but were not irrigated. This "nonirrigated" endmember was used to compute a Normalized Difference Vegetation Index (NDVI) surplus, defined as the difference between the NDVI signals of the irrigated and nonirrigated endmembers. The NDVI signals from irrigated areas remains relatively constant throughout the year, whereas the signal from nonirrigated areas rises and

  11. Assessment of the influence of climate condition on a migration rate of the 90Sr in the unsaturated zone in the Kirov and Sverdlovsk Region, Russia

    Science.gov (United States)

    Kurinova, Natalia; Dediulina, Ekaterina

    2016-04-01

    In this research, the transport of 90Sr with unsaturated flow in the same geological section (0.5 m top soil, from 0.5 to 6.0 m sand) was taken under consideration in two regions: Kirov and Sverdlovsk Region, Russia. The modeling schematization assumed that the nuclide polluted top soil to the depth of 0.2 m and from this point are transported with infiltration of precipitation during 100 year. The modeling were conducted in Hydrus 1D. The climate classification based on the Budyko aridity index (Budyko 1958) was used to define climate differences between regions. According this classification climate in both are temperate continental but the biggest differences is in the wetting degree. The Kirov region has the aridity index about 0.70; there is overwatering conditions, which means that average annual precipitation exceeds the potential evapotranspiration. The Sverdlovsk region has the aridity index about 1.04; there is the optimal watering conditions. The results of modeling of the 90Sr migration process showed the transport dynamic dependence on wetting degree. At the end of the 100-year period, the 90Sr reached the depth of 1.3 m in Kirov region and 1.0 m in Sverdlovsk.

  12. Rainfed agriculture in a semi-arid tropical climate. Aspects of land- and water management for red soils in India

    NARCIS (Netherlands)

    Huibers, F.P.

    1985-01-01

    Rainfed agriculture is defined as the production of field crops that completely depend on the local precipitation for their water supply. Although in the semi-arid tropics the mean annual precipitation might seem to be sufficient to grow (adapted) crops, its variability over the years and its errati

  13. Future Water Management in the South Platte River Basin: Impacts of Hydraulic Fracturing, Population, Agriculture, and Climate Change in a Semi-Arid Region.

    Science.gov (United States)

    Walker, E. L.; Hogue, T. S.; Anderson, A. M.; Read, L.

    2015-12-01

    In semi-arid basins across the world, the gap between water supply and demand is growing due to climate change, population growth, and shifts in agriculture and unconventional energy development. Water conservation efforts among residential and industrial water users, recycling and reuse techniques and innovative regulatory frameworks for water management strive to mitigate this gap, however, the extent of these strategies are often difficult to quantify and not included in modeling water allocations. Decision support systems (DSS) are purposeful for supporting water managers in making informed decisions when competing demands create the need to optimize water allocation between sectors. One region of particular interest is the semi-arid region of the South Platte River basin in northeastern Colorado, where anthropogenic and climatic effects are expected to increase the gap between water supply and demand in the near future. Specifically, water use in the South Platte is impacted by several high-intensity activities, including unconventional energy development, i.e. hydraulic fracturing, and large withdrawals for agriculture; these demands are in addition to a projected population increase of 100% by 2050. The current work describes the development of a DSS for the South Platte River basin, using the Water Evaluation and Planning system software (WEAP) to explore scenarios of how variation in future water use in the energy, agriculture, and municipal sectors will impact water allocation decisions. Detailed data collected on oil and gas water use in the Niobrara shale play will be utilized to predict future sector use. We also employ downscaled climate projections for the region to quantify the potential range of water availability in the basin under each scenario, and observe whether or not, and to what extent, climate may impact management decisions at the basin level.

  14. Analysis of soil moisture condition under different land uses in the arid region of Horqin sandy land, northern China

    Science.gov (United States)

    Niu, C. Y.; Musa, A.; Liu, Y.

    2015-10-01

    Land use plays an important role in controlling spatial and temporal variations of soil moisture by influencing infiltration rates, runoff and evapotranspiration, which is important to crop growth and vegetation restoration in semiarid environments, such as Horqin sandy land in north China. However, few studies have been conducted comparing differences of dynamics of soil water conditions and the responses of soil to infiltration under different land use types in semiarid area. Five different land use types were selected to analyze soil moisture variations in relation to land use patterns during the growing season of 2 years. Results showed that soil moisture condition was affected by different land uses in semi-arid sandy soils. The higher soil moisture content among different land uses was exhibited by the grassland, followed by cropland, poplar land, inter-dunes and shrub land. The temporal variations of soil moisture in different land uses were not always consistent with the rainfall due to the dry sequence. Moreover, soil water at the surface, in the root zone and at the deep soil layer indicated statistical differences for different types of land cover. Meanwhile, temporal variations of soil moisture profile changed with precipitation. However, in the deep soil layer, there was a clear lag in response to precipitation. In addition, seasonal variations of profile soil moisture were classified into two types: increasing and waving types. And the stable soil water layer was at 80-120 cm. Furthermore, the infiltration depth exhibited a positive correlation with precipitation under all land uses. This study provided an insight into the implications for land and agricultural water management in this area.

  15. Analysis of soil moisture condition under different land uses in arid region of Horqin Sandy Land, northern China

    Science.gov (United States)

    Niu, C.; Musa, A.; Liu, Y.

    2015-07-01

    Land use plays an important role in controlling spatial and temporal variations of soil moisture by influencing infiltration rates, runoff, and evapotranspiration, which is substantive meaning to crop growth and vegetation restoration in semiarid environments, such as the Horqin Sandy Land in north China. However, few studies have been conducted comparing differences of dynamics of soil water conditions and the responses of soil water to precipitation infiltration under different land use types in this semiarid region. Five different land use types were selected to analyze soil moisture variations in relation to land use patterns during the growing season of two years. Results showed that soil moisture condition was affected by different land uses in semi-arid sandy land. The order of soil moisture (from high to low) among different land uses was grassland, cropland, poplar land, inter-dunes and shrub land. The temporal variations of soil moisture in different land uses were not always consistent with the rainfall due to the dry sequence. Moreover, soil water in surface, root zone and deep soil layer indicated statistical difference for different land covers. Meanwhile, temporal variations of soil moisture profile changed with precipitation. However, in deep soil layer, there was a clear lag in response to precipitation. In addition, seasonal variations of profile soil moisture were classified into two types: increasing and waving types. And the stable soil water layer was at 80-120 cm. Furthermore, the infiltration depth exhibited a positive correlation with precipitation under all land uses. This study provided an insight into the implications for land and agricultural water management in this area.

  16. Groundwater dating with radiocarbon: application to an aquifer under semi-arid conditions in the south of Morocco (Guelmime).

    Science.gov (United States)

    Bouhlassa, S; Aiachi, A

    2002-04-01

    Radiocarbon dating is based on measuring the loss of the parent radionuclide (14C) in a given sample. This assumes two key features of the system. The first is that the initial concentration of the parent is known and has remained constant in the past. The second is that the system is closed to subsequent gains or losses of the parent, except through radioactive decay. But, the reaction and evolution of the carbonate system strongly dilute the initial 14C activity in dissolved inorganic carbon (DIC). The result is an artificial "aging" of groundwater by dilution of 14C. Unravelling the relevant processes and distinguishing 14C decay from 14C dilution is an engaging geochemical problem. Several attempts to overcome these problems have been made during the past 30 years and a number of possible correction procedures have been presented by different authors. Environmental isotopes study (13C, 14C) from the aquifers of the Guelmime under semi-arid conditions provides new information on recharge zones, mixing zones and the circulation routes of water. The combination of logP(CO2), the saturation index of dolomite and calcite, HCO3, delta13C, 14C and pH along flow paths can provide an indication of open- and closed-system conditions in the Oumlaachar and Seyyad sub-basins. This approach of geochemical analysis, when combined with correction procedures, allows us to understand age and recharge in the Guelmime aquifer. 14C groundwater ages range from modern to about 2700 years in this aquifer, and indicate recharge values of 0.55-15 mm/yr. PMID:11999164

  17. Groundwater dating with radiocarbon: application to an aquifer under semi-arid conditions in the south of Morocco (Guelmime)

    International Nuclear Information System (INIS)

    Radiocarbon dating is based on measuring the loss of the parent radionuclide (14C) in a given sample. This assumes two key features of the system. The first is that the initial concentration of the parent is known and has remained constant in the past. The second is that the system is closed to subsequent gains or losses of the parent, except through radioactive decay. But, the reaction and evolution of the carbonate system strongly dilute the initial 14C activity in dissolved inorganic carbon (DIC). The result is an artificial 'aging' of groundwater by dilution of 14C. Unravelling the relevant processes and distinguishing 14C decay from 14C dilution is an engaging geochemical problem. Several attempts to overcome these problems have been made during the past 30 years and a number of possible correction procedures have been presented by different authors. Environmental isotopes study (13C, 14C) from the aquifers of the Guelmime under semi-arid conditions provides new information on recharge zones, mixing zones and the circulation routes of water. The combination of logPCO2, the saturation index of dolomite and calcite, HCO3-, δ13C, 14C and pH along flow paths can provide an indication of open- and closed-system conditions in the Oumlaachar and Seyyad sub-basins. This approach of geochemical analysis, when combined with correction procedures, allows us to understand age and recharge in the Guelmime aquifer. 14C groundwater ages range from modern to about 2700 years in this aquifer, and indicate recharge values of 0.55-15 mm/yr

  18. Effect of diet supplementation on growth and reproduction in camels under arid range conditions

    Directory of Open Access Journals (Sweden)

    Abdouli H.

    2001-01-01

    Full Text Available Eighteen pregnant dromedary females (Camelus dromedarius were used to determine the effect of concentrate supplement on growth and reproductive performances in peri-partum period. The females were divided into supplemented (n = 9; S and unsupplemented (n = 9; C experimental groups. All animals grazed, with one mature male, 7 to 8 hours per day on salty pasture rangelands. During night, they were kept in pen, where each female of group S received 4 kg per day of concentrate supplement during the last 3 months of gestation and 5 kg per day during the first 3 months post-partum. During the last 90 days of gestation daily body weight gain (DBG was at least tenfold more important in group S than in group C (775 g vs. 72 g respectively. Supplementation affected birth weight of offspring (30.3 kg vs. 23.4 kg and its DBG (806 g vs. 430 g in group S and group C respectively. During the post-partum period, females in group S gained in weight (116 g per day whereas females in group C lost more than 200 g per day. The mean post-partum interval to the first heat and the percentage of females in heat were 29.5 day and 44.4/ vs. 41.2 day and 71.4/ for the C and S groups, respectively. We conclude that under range conditions, dietary supplementation of dromedary during late pregnancy stage and post-partum period improves productive and reproductive parameters.

  19. Capability of multiple selection criteria to evaluate contrasting spring wheat germplasms under arid conditions

    International Nuclear Information System (INIS)

    Selection criteria that would evaluate a large number of germplasm in a rapid and non-destructive manner would be considered advantageous in plant breeding programs. Trade-off between traditional and non-destructive screening criteria in evaluating 90 wheat accessions under water shortage was tested using multivariate statistical techniques. Only three irrigations during the growing cycle of germplasm were applied with the amount of water totalling 2550 m /sup 3/ ha /sup -1/. Sequential path analysis identified one traditional trait (grain weight per plant) and two non-destructive traits (leaf area index and stomatal conductance) as important first-order traits that influenced final grain yield. The three traits, taken together, explained 96.8 percentage of the total variation in grain yield. Total dry weight per plant, green leaf area per plant, harvest index, grain number per plant, leaf water content and canopy temperature were identified as important second-order traits that influenced grain yield. Although canopy temperature was ranked as a second-order trait, it explained 64.4 percentage of the total variation in stomatal conductance. Approximately 78.0 percentage of the total variation in grain weight or leaf area index was explained by the leaf water content (66.2 percentage) and total dry weight (11.5 percentage). The 90 examined spring wheat germplasms were grouped into five clusters based on all agro-physiological traits using the centroid linkage method. The tested wheat germplasm that produce high grain yield under water shortage were characterised by good performance of certain rapid, easy and non-destructive physiological traits such as high leaf area index, high stomatal conductance and low canopy temperature. Therefore, these three traits could be used in combination as quick and easy screening criteria to select suitable genotypes for water-limiting conditions. (author)

  20. Can calcretes be used to date pedogenic processes in soil profiles under semi arid climate ? An example from U-Th isochrons in calcretes from South India.

    Science.gov (United States)

    Durand, Nicolas; Hamelin, Bruno; Deschamps, Deschamps; Gunnel, Yanni; Curmi, Pierre

    2015-04-01

    Pedogenic carbonates, such as calcretes, have often been questioned as possible markers of the pedogenetic evolution of soil profiles under semi-arid climate. However, providing precise chronological constraints on their formation is a perequisite to determine the climatic and paleo-environmental conditions prevailing during and after their formation, and to improve our understanding of the physical and chemical conditions that promoted their development and preservation. On the other hand, these authigenic calcium carbonate precipitates provide us with an interesting test of the U-Th radioactive disequilibrium dating method, the reliability of which has been demonstrated extensively in aragonitic marine formations, and calcitic continental speleothems, but remain much more questionable in highly porous and chemically complex media such as soil profiles. In this study, we combined U-Th systematics with detailed micromorphologic observations of calcretes from South India, investigated at different spatial scales, from the landscape to the soil profile, down to the micro-fabrics of the samples. The U-Th analyses were performed by Thermo-Ionization Mass Spectrometry. Since calcretes are impure carbonates, mixed with various amounts of parent rock and weathered minerals, all ages had to be computed using the isochron technique to correct for the detrital component. This method involves the extraction of several coeval subsamples from a single soil horizon and their U-Th analyses after total dissolution (TDS method). The isochron age is derived from the slope of the mixing line between the pure authigenic carbonate and the detrital phase, and the precision established statistically using the probability of fit and weighted mean deviations (MSWD). Our results show that each set of samples taken from decimetric blocks is characterized by a well defined isochron line, clearly distinct from each other in the 3D Osmond diagram (232Th/238U; 230Th/238U ; 234U/238U). The

  1. Predicting Weather Conditions and Climate for Mars Expeditions

    Science.gov (United States)

    Read, P. L.; Lewis, S. R.; Bingham, S. J.; Newman, C. E.

    Weather and climatic conditions are among the most important factors to be taken into account when planning expeditions to remote and challenging locations on Earth. This is likely to be equally the case for expedition planners on Mars, where conditions (in terms of extremes of temperature, etc.) can be at least as daunting as back on Earth. With the success of recent unmanned missions to Mars, such as NASA's Mars Pathfinder, Mars Global Surveyor and Mars Odyssey, there is now a great deal of information available on the range of environ- mental conditions on Mars, from the tropics to the CO2 ice-covered polar caps. This has been further supple- mented by the development of advanced numerical models of the Martian atmosphere, allowing detailed and accurate simulations and predictions of the weather and climate across the planet. This report discusses the main weather and climate variables which future Martian human expedition planners will need to take into account. The range of conditions likely to be encountered at a variety of typical locations on Mars is then considered, with reference to predictions from the ESA Mars Climate Database.

  2. Modelling climate change impacts on stream habitat conditions

    DEFF Research Database (Denmark)

    Boegh, Eva; Conallin, John; Karthikeyan, Matheswaran;

    , climate impacts on stream ecological conditions were quantified by combining a heat and mass stream flow with a habitat suitability modelling approach. Habitat suitability indices were developed for stream velocity, water depth, water temperature and substrate. Generally, water depth was found...

  3. Transferability of SWAT model parameters for flow simulations under changed climatic conditions

    Science.gov (United States)

    Zhu, Q.; Zhang, X.; Ma, C.; Xu, Y.

    2013-12-01

    Hydrological models are widely employed for climate change impact assessment. Parameters calibration is a step of great importance in using hydrological models to simulate flows. In most studies, parameters estimated from observations are assumed to remain valid for future climate conditions. However, this might not be true due to non-stationarity. In this study, SWAT model is used to evaluate the transferability of parameters for flow simulations under changed climatic conditions. The model is set up in Quzhou catchment, one sub-basin of Qiantang River Basin in East China. After a preliminary sensitivity analysis, ten parameters are selected as sensitive ones and used in the calibration. Based on the aridity index and flows, three sub-periods are selected from the period (1961-2006): wet sub-period (1992-1995), intermediate sub-period (1965-1968) and dry sub-period (2003-2006). These three sub-periods are calibrated separately via SUFI-2 method, which results in three different sets of parameters. A regional climate model PRECIS (Providing REgional Climates for Impacts Studies) is used to downscale the global climate model (HadCM3) outputs. The downscaled precipitation and temperature are put into SWAT model to simulate future flows in the future period (2011-2040). The three sets of parameters are employed separately to simulate future flows. The results show that in the calibration the Nash-Sutcliffe coefficients of 1000 simulations which are larger than 0.6 in wet, intermediate and dry sub-periods are more than 77.3%, 97% and 71.7% respectively. By comparing the ranges of those three sets parameters, it is found that three parameters about soil are very different from each other, which are available water capacity of the soil layer, saturated hydraulic conductivity and soil depth. From the uncertainty range (95PPU) of future flow simulations, it is known that flows simulated by the wet set of parameters are similar to those by the intermediate set of parameters

  4. Short Communication: Rhizosphere bacteria containing ACC-deaminase conferred drought tolerance in wheat grown under semi-arid climate

    OpenAIRE

    Masood Ahmad Shakir; Asghari Bano; and Muhammad Arshad

    2012-01-01

    Certain rhizobacteria have the potential of lowering endogenous ethylene levels in plants because of their 1- aminocyclopropane-1-carboxylate (ACC)-deaminase activity and promoting root growth. This mechanism is of great agronomic significance under stress environments, which are known to induce accelerated production of ethylene. Thirty rhizobacteria were isolated from rhizosphere of wheat (Triticum aestivum L.) growing in the Southern Punjab, a semi-arid region of Pakistan. Rhizobacteria we...

  5. Shade shelters increase survival and photosynthetic performance of oak transplants at abandoned fields in semi-arid climates

    Institute of Scientific and Technical Information of China (English)

    Claudia González-Salvatierra; Ernesto Iván Badano; Joel Flores; Juan Pablo Rodas

    2013-01-01

    Forest restorations conducted in semiarid,seasonally dry climates must deal with the intense drought stress that affects tree seedlings during the dry season.Although this water deficit is the most commonly invoked source of mortality for seedlings,several other environmental factors may also preclude survival of transplants.For instance,it has been widely reported that excessive light reduces the efficiency of the photosynthetic apparatus,hence decreasing plant survival,but most seedling transplants in deforested areas are conducted under these light conditions.This study is focused in determining whether excessive light affects the photosynthetic performance and survival of Quercus coccolobifolia,a Mexican oak species,when their seedlings are transplanted in semiarid deforested areas.Further,this study tests the possibility of using artificial shade shelters to improve the ecophysiological performance and survival of seedlings.Oak seedlings were transplanted under full sunlight conditions and beneath artificial shade shelters of two different colors:white and black.To reduce water stress,and hence isolate the effects of light treatments,a drip irrigation system was implemented at each experimental plot.Seedling survival was monitored weekly for 128 days and photosynthetic performance was assessed by measuring chlorophyll fluorescence at three opportunities during the experiment.Sun-exposed seedlings showed lower photosynthetic performance and survival rates than those beneath shelters of both colors.These results suggest that sunlight damage can reduce seedling survival when they are transplanted in exposed sites,and that shade shelters can improve the success of forest restoration programs in semiarid climates.

  6. Temperature profile in apricot tree canopies under the soil and climate conditions of the Romanian Black Sea Coast

    Science.gov (United States)

    Paltineanu, Cristian; Septar, Leinar; Chitu, Emil

    2016-03-01

    The paper describes the temperature profiles determined by thermal imagery in apricot tree canopies under the semi-arid conditions of the Black Sea Coast in a chernozem of Dobrogea Region, Romania. The study analyzes the thermal vertical profile of apricot orchards for three representative cultivars during summertime. Measurements were done when the soil water content (SWC) was at field capacity (FC) within the rooting depth, after intense sprinkler irrigation applications. Canopy temperature was measured during clear sky days at three heights for both sides of the apricot trees, sunlit (south), and shaded (north). For the SWC studied, i.e., FC, canopy height did not induce a significant difference between the temperature of apricot tree leaves (Tc) and the ambient air temperature (Ta) within the entire vertical tree profile, and temperature measurements by thermal imagery can therefore be taken at any height on the tree crown leaves. Differences between sunlit and shaded sides of the canopy were significant. Because of these differences for Tc-Ta among the apricot tree cultivars studied, lower base lines (LBLs) should be determined for each cultivar separately. The use of thermal imagery technique under the conditions of semi-arid coastal areas with low range of vapor pressure deficit could be useful in irrigation scheduling of apricot trees. The paper discusses the implications of the data obtained in the experiment under the conditions of the coastal area of the Black Sea, Romania, and neighboring countries with similar climate, such as Bulgaria and Turkey.

  7. Window of Opportunity: The Climatic Conditions of the Lewis and Clark Expedition of 1804 1806.

    Science.gov (United States)

    Knapp, Paul A.

    2004-09-01

    Lewis and Clark's entry into to the American West in search of an inland Northwest Passage is considered among the greatest expeditions in American history. The Corps of Discovery were also lucky as their travels west of the 100th meridian occurred during a “window” of generally favorable climatic conditions. Use of reconstructed summer Palmer drought severity index (PDSI) values from 1700 1978 indicate that drought frequency at locations along the Lewis and Clark trail ranged from 4 to 12 yr and that the probability of encountering a drought either on the outbound or return trip approached 50% at some locations. Exact date comparisons of meteorological conditions during periods of extended encampment (i.e., 1 5 months) between 1804 06 with long-term records of nearby weather stations indicate that the Corps of Discovery avoided drought and traveled during a cooler and/or substantially wetter period than historical averages. Examination of reconstructed Southern Oscillation index (SOI) and Pacific decadal oscillation (PDO) values suggest wetter conditions prevailed in 1804 06 because of the co-occurrence of La Niña conditions during a cold PDO phase. Although the Corps of Discovery suffered hardships because of the wetter conditions, they avoided the more serious consequences of severe droughts that occurred in 1800 and 1808. Drought conditions along the semiarid and arid portions of the trail would have reduced forage yield for the game that were their principal source of food and increased their chances for starvation. Additionally, lower streamflow conditions along their principal navigation routes would have required greater effort and time to haul their supplies to the Continental Divide, perhaps delaying their expedition by a year.

  8. Performance of desiccant air conditioning system with geothermal energy under different climatic conditions

    International Nuclear Information System (INIS)

    Highlights: • The performance of the hybrid air conditioning system is studied. • The influence of important operating parameters are estimated. • The ventilation, makeup and mix cycles are investigated at different climate. • The highest COP of the hybrid air conditioning system is 1.03. • The hybrid system provides a human thermal comfort at different climates. - Abstract: Energy saving still and continue a major seek in our life, due to the continuous increase in energy consumptions. So, a desiccant air conditioning system with geothermal energy is conducted in the current study. The thermal analysis of air conditioning system with its different components desiccant wheel, solar collector, heat exchanger, ground heat exchanger and water spray evaporative cooler is presented. Three different air conditioning cycles are simulated in the current study for different zones like: hot-dry zone, warm-dry zone, hot-humid zone and the warm-humid zone. The results show that the desiccant air conditioning system successfully provides a better thermal comfort condition in different climates. This hybrid system significantly decreases the supplied air temperature from 12.7 to 21.7 °C at different climate zones. When ωin,air and TReg increasing, COP decreases and the ventilation cycle provides the better COP. The highest COP value of the desiccant air conditioning system is about 1.03 while the lowest value is about 0.15. The SHR of makeup cycle is higher than that ventilation cycle at warm and hot-humid zone and vice versa at warm and hot-dry zone. The highest SHR value of the desiccant air conditioning system is about 0.99 while the lowest value is about 0.2. The Tsup,air, ωsup,air, COP and SHR isolines may easily be used for pre-evaluating of various cooling cycles in different climates. The hybrid system provides a human thermal comfort at different climates

  9. Unlocking the biogeochemical black box: What drives microbial response to climate forcing in semi-arid soils?

    Science.gov (United States)

    Moravec, B. G.; McLain, J. E.; Lohse, K. A.

    2009-12-01

    Microbial mediated cycling of carbon (C) and nitrogen (N) and their loss from soils are closely linked to soil moisture and temperature. Yet, it is unclear how microbial communities will respond to climatic forcing (namely increased inter-annual precipitation variability and severe drought) and to what extent parent material controls these responses. We used Real Time Polymerase Chain Reaction (RT-PCR) and C utilization assays to determine the relative abundance and diversity of microbial populations during pre-, mid- and post-monsoon time intervals at four sites along a steep elevation gradient (temperature and precipitation range of >10°C and >50 cm, respectively) in the Santa Catalina Mountains, AZ. Contrasting parent materials (schist and granite) were paired at elevations. RT-PCR results showed large increases of bacterial and fungal biomarkers at high elevations with the onset of precipitation (pre- to mid- monsoon conditions) (as much as 824%). In contrast, bacteria biomarkers did not change at low elevation granite site as a result of the onset of precipitation whereas fungal biomarkers increased by 177% at this site. Both bacteria and fungal biomarkers increased substantially at low elevation schist sites with the onset of precipitation. Finally, C utilization assays indicated that high elevation sites had a relatively high diversity of C utilization compared to low elevation soils. We hypothesize that increased bacterial and fungal abundance in low elevation schist-derived soils relative to granite soils after the onset of monsoon rains may be a function of soil texture, with higher clay content in schist soils leading to higher soil moisture availability. Alternatively, differences in microbial responses may be due to higher C availability in schist soils compared to granite soils. Higher C utilization diversity as well as similar bacteria and fungal biomarker responses found at high elevation sites (both granite and schist soils) in response to

  10. Potential soil organic carbon stocks in semi arid areas under climate change scenarios: an application of CarboSOIL model in northern Egypt

    Science.gov (United States)

    Muñoz-Rojas, Miriam; Abd-Elmabod, Sameh K.; Jordán, Antonio; Zavala, Lorena M.; Anaya-Romero, Maria; De la Rosa, Diego

    2014-05-01

    1. INTRODUCTION Climate change is predicted to have a large impact on semi arid areas which are often degraded and vulnerable to environmental changes (Muñoz-Rojas et al., 2012a; 2012b; 2013). However, these areas might play a key role in mitigation of climate change effects through sequestration of carbon in soils (United Nations, 2011). At the same time, increasing organic carbon in these environments could be beneficial for soil erosion control, soil fertility and, ultimately, food production (Lal, 2004). Several approaches have been carried out to evaluate climate change impacts on soil organic carbon (SOC) stocks, but soil carbon models are amongst the most effective tools to assess C stocks, dynamics and distribution and to predict trends under climate change scenarios (Jones et al., 2005 ). CarboSOIL is an empirical model based on regression techniques and developed to predict SOC contents at standard soil depths of 0 to 25, 25 to 50 and 50-75 cm (Muñoz-Rojas et al., 2013). CarboSOIL model has been designed as a GIS-integrated tool and is a new component of the agroecological decision support system for land evaluation MicroLEIS DSS (De la Rosa et al., 2004). 2. GENERAL METHODS In this research, CarboSOIL was applied in El-Fayoum depression, a semi arid region located in northern Egypt with a large potential for agriculture (Abd-Elmabod et al, 2012). The model was applied in a total of six soil-units classified according the USDA Soil Taxonomy system within the orders Entisols and Aridisols under different climate climate change scenarios. Global climate models based on the Organisation for Economic Co-operation and Development (Agrawala at al., 2004) and the Intergovernmental Panel on Climate Change (IPCC, 2007) were applied to predict short-, medium- and long-term trends (2030, 2050 and 2100) of SOC dynamics and sequestration at different soil depths (0-25, 25-50 and 50-75) and land use types (irrigated areas, olive groves, wheat, cotton and other annual

  11. The net effect of abiotic conditions and biotic interactions in a semi-arid ecosystem NE Spain: implications for the management and restoration.

    Science.gov (United States)

    Pueyo, Yolanda; Arroyo, Antonio I.; Saiz, Hugo; Alados, Concepción L.

    2014-05-01

    Degradation in arid and semiarid lands can be irreversible without human intervention, due to a positive plant-soil feedback where the loss of vegetation cover leads to soil degradation, which in turn hampers plant establishment. Human intervention in restoration actions usually involves the amendment of the degraded abiotic conditions, revegetation of bare areas, or both. However, abiotic amelioration is often expensive and too intrusive, and revegetation is not successful in many cases. Biotic interactions between plants, and more specifically facilitation by a "nurse" plant, have been proposed as a new via to take profit of improved abiotic conditions without intervention, and to increase the success rate of revegetation actions. But "nurse" plants can also interfere with others (i.e. by competition for resources or the release of allelopathic compounds), and the net balance between facilitation and interference could depend on plant types involved. We present recent observational and experimental studies performed in the semiarid ecosystems of the Middle Ebro Valley (NE Spain) about the role of abiotic conditions and biotic interactions in the productivity, dynamics and diversity of plant communities under different stress conditions (aridity and grazing). We found that all plant types studied (shrubs and perennial grasses) improved abiotic conditions (soil temperature and water availability for plants) with respect to open areas. However, only some shrubs (mainly Salsola vermiculata) had a positive net balance in the biotic interactions between plants, while other shrubs (Artemisia herba-alba) and perennial grasses (Lygeum spartum) showed interference with other plants. Moreover, the net balance between facilitation and interference among plants in the community shifted from competitive to neutral or from neutral to facilitative with increasing aridity. Grazing status did not strongly change the net biotic interactions between plants. Our results suggest that

  12. Physiological response of autumn planted sugarcane to soil moisture depletion and planting geometry on different soils under arid conditions

    International Nuclear Information System (INIS)

    A field experiment was conducted on autumn planted sugarcane cv. HSF 240 at two locations, i.e., Research Area at Rakh Bibi Campus Gomal University, Dara Ismail Khan on Silty clay soil and Main Line Lower Land Reclamation Research Station, Chak No 37 TDA (Thal Development Authority) Bhakkar, Pakistan on sandy loam soil during 2003-04 and 2004-05. The experiment was laid out according to a randomized complete block design (RCBD) with a split plot arrangement having four replications. There were four available soil moisture depletion levels (ASMDL) including ASMDL1 -20%, ASMDL2 -40%, ASMDL3 - 60% and ASMDL4 -80%, which were kept in main plots and four planting patterns viz. G/sub 1/-60 cm, G2 -75 cm spaced single row planting patterns and G3 -30/90, G/sub 4/ -30/120 cm spaced paired row strip planting pattern, assigned to the sub plots having net subplot size of 24 m/sup 2/. Analysis of pooled data of both locations showed that Leaf area index (LAI), Leaf area duration (LAD), Crop growth rate (CGR) and Net assimilation rate (NAR) were significantly affected by ASMDL and were maximum at 40% ASMD level followed by 60%, 20% and the minimum at 80% ASMD level during both years. Whereas LAD, CGR and NAR were also significantly affected and were maximum in 30/90cm spaced paired row strip planting pattern followed by 75 cm and 60cm and minimum in 30/120cm spaced paired row strip planting pattern during both years. Treatments interactive effects of ASMD levels and planting patterns on LAD, CGR and NAR were significantly different except LAI and were maximum in 40% ASMDL x 30/90cm spaced paired row strip planting pattern and minimum in 80% ASMDL x 30/120 cm spaced paired row strip planting pattern during both years. Therefore it was concluded that under arid conditions on Silty clay and sandy loam soils sugar cane crop gave best physiological performance by irrigation at 40% ASMD level and sowing in 30/90 cm spaced paired row strip planting pattern. (author)

  13. Trends and responses to global change of China's arid regions

    Institute of Scientific and Technical Information of China (English)

    Weixi YANG

    2009-01-01

    Ⅰ analyzed and elaborated the trends in and responses to global change in arid regions of China, from the perspective of nine variables, i.e., temperature, precipitation, river runoff, melting glaciers, water level of lakes, wind power and evaporation, vegetation, oases, and desertification. The climate and hydrology data Ⅰ citedrepresent many years of observations. Ⅰ conclude that, since the 1980s, the climate in arid regions of China has clearly changed with rising temperatures and precipitation in most areas. Wind power and the number of galestorm days have continuously decreased, which resulted in an improvement of humid conditions and increases in river discharge and water levels of lakes. Simultaneously, vegetation also has improved and the process of deserti-fication has essentially been arrested. Although there are some unfavorable developments, such as decreased river flows or flow interruptions and downstream oases have suffered from degradation, these incidental cases should not distract our attention from the generally favorable trends during the middle and late 20th century. These discordant phenomena are not consequences of climate change but rather of unsuitable human activities. Despitea substantial increase in precipitation, the level of the original precipitation was so small that any increase in precipitation was still small. As a result, none of the fundamental conditions such as a scarcity of water resources and precipitation nor the landscape of drought-ridden deserts in the arid regions will change. The vulnerability of the eco-environmental system in the arid regions will not change fundamentally either in the near future.

  14. Optimal Contracting for Cattle Feeding: An Assessment of Climatic Conditions

    OpenAIRE

    Rahman, Shaikh Mahfuzur

    2010-01-01

    A unique approach using a biophysical growth model from the animal science literature is used to examine optimal contract cattle feeding behavior under alternative climatic conditions. The examination of incentives and outcomes in an unusually comprehensive contract parameter and behavioral space is made possible by combining simulated feedlot and carcass performance of a large set of cattle with public price and weather data. The model uniquely fits typical risk aversion levels and rationali...

  15. Global flood risks under changing climate and socioeconomic conditions

    Science.gov (United States)

    Sperna Weiland, Frederiek; Ward, Philip; Bouwman, Arno; Ligtvoet, Willem; van Beek, Rens; Winsemius, Hessel

    2013-04-01

    Worldwide major flood events result in both economic losses and large numbers of casualties. Recent global scale studies indicate that in many regions of the world discharge extremes are likely to increase under changing climate conditions. However, few studies have so far examined how these changes in climate conditions may affect flood risk (defined here as the probability of a flood multiplied by the consequences). In the current study we investigate the impacts of changing climate and socioeconomic conditions on flood extents and depths, and also assess the potential impacts on flood risk. The study is conducted on a global scale, thereby indicating in which regions of the world flood risk is likely to change most. To assess global food risk under changing conditions, we combined socio-economic data from the Integrated Model to Assess the Global Environment (IMAGE) framework of the Netherlands Environmental Assessment Agency (PBL) with high resolution maps of inundation depth (1 km). To this end, projections from a number of GCMs were bias-corrected and used to force the global hydrological model PCR-GLOBWB which simulates (amongst other variables) global maps with daily flood volumes on a 0.5 degree resolution. These time series were used to derive flood volume maps for multiple return periods, which were downscaled to inundation depth maps at 1 km resolution using a 1 km resolution DEM. Finally, these high resolution flood maps were combined with spatial datasets on future GDP and population density from the IMAGE model. Results are presented on both the global scale and at the country level. We believe that the obtained flood extend and flood risk maps can assist development agencies in planning climate adaptation investments that aim to reduce flood risks.

  16. Variable climatic conditions dominate recent phytoplankton dynamics in Chesapeake Bay

    Science.gov (United States)

    Harding, Lawrence W., Jr.; Mallonee, Michael E.; Perry, Elgin S.; Miller, W. David; Adolf, Jason E.; Gallegos, Charles L.; Paerl, Hans W.

    2016-03-01

    Variable climatic conditions strongly influence phytoplankton dynamics in estuaries globally. Our study area is Chesapeake Bay, a highly productive ecosystem providing natural resources, transportation, and recreation for nearly 16 million people inhabiting a 165,000-km2 watershed. Since World War II, nutrient over-enrichment has led to multiple ecosystem impairments caused by increased phytoplankton biomass as chlorophyll-a (chl-a). Doubled nitrogen (N) loadings from 1945–1980 led to increased chl-a, reduced water clarity, and low dissolved oxygen (DO), while decreased N loadings from 1981–2012 suggest modest improvement. The recent 30+ years are characterized by high inter-annual variability of chl-a, coinciding with irregular dry and wet periods, complicating the detection of long-term trends. Here, we synthesize time-series data for historical and recent N loadings (TN, NO2 + NO3), chl-a, floral composition, and net primary productivity (NPP) to distinguish secular changes caused by nutrient over-enrichment from spatio-temporal variability imposed by climatic conditions. Wet years showed higher chl-a, higher diatom abundance, and increased NPP, while dry years showed lower chl-a, lower diatom abundance, and decreased NPP. Our findings support a conceptual model wherein variable climatic conditions dominate recent phytoplankton dynamics against a backdrop of nutrient over-enrichment, emphasizing the need to separate these effects to gauge progress toward improving water quality in estuaries.

  17. The transferability of hydrological models under nonstationary climatic conditions

    Directory of Open Access Journals (Sweden)

    C. Z. Li

    2012-04-01

    Full Text Available This paper investigates issues involved in calibrating hydrological models against observed data when the aim of the modelling is to predict future runoff under different climatic conditions. To achieve this objective, we tested two hydrological models, DWBM and SIMHYD, using data from 30 unimpaired catchments in Australia which had at least 60 yr of daily precipitation, potential evapotranspiration (PET, and streamflow data. Nash-Sutcliffe efficiency (NSE, modified index of agreement (d1 and water balance error (WBE were used as performance criteria. We used a differential split-sample test to split up the data into 120 sub-periods and 4 different climatic sub-periods in order to assess how well the calibrated model could be transferred different periods. For each catchment, the models were calibrated for one sub-period and validated on the other three. Monte Carlo simulation was used to explore parameter stability compared to historic climatic variability. The chi-square test was used to measure the relationship between the distribution of the parameters and hydroclimatic variability. The results showed that the performance of the two hydrological models differed and depended on the model calibration. We found that if a hydrological model is set up to simulate runoff for a wet climate scenario then it should be calibrated on a wet segment of the historic record, and similarly a dry segment should be used for a dry climate scenario. The Monte Carlo simulation provides an effective and pragmatic approach to explore uncertainty and equifinality in hydrological model parameters. Some parameters of the hydrological models are shown to be significantly more sensitive to the choice of calibration periods. Our findings support the idea that when using conceptual hydrological models to assess future climate change impacts, a differential split-sample test and Monte Carlo simulation should be used to quantify uncertainties due to

  18. Evaluation of an extreme-condition-inverse calibration remote sensing model for mapping energy balance fluxes in arid riparian areas

    OpenAIRE

    Hong, S.-H.; Hendrickx, J. M. H.; Kleissl, J.; Allen, R.G.; W. G. M. Bastiaanssen; R. L. Scott; A. L. Steinwand

    2014-01-01

    Accurate information on the distribution of the surface energy balance components in arid riparian areas is needed for sustainable management of water resources as well as for a better understanding of water and heat exchange processes between the land surface and the atmosphere. Since the spatial and temporal distributions of these fluxes over large areas are difficult to determine from ground measurements alone, their prediction from remote sensing data is ...

  19. Agricultural pests under future climate conditions: downscaling of regional climate scenarios with a stochastic weather generator

    Science.gov (United States)

    Hirschi, M.; Stöckli, S.; Dubrovsky, M.; Spirig, C.; Rotach, M. W.; Calanca, P.; Samietz, J.

    2010-09-01

    As a consequence of current and projected climate change in temperate regions of Europe, agricultural pests and diseases are expected to occur more frequently and possibly to extend to previously unaffected regions. Given their economic and ecological relevance, detailed forecasting tools for various pests have been developed, which model the infestation depending on actual weather conditions. Assessing the future risk of pest-related damages therefore requires future weather data at high temporal and spatial resolution. In particular, pest forecast models are often not based on screen temperature and precipitation alone (i.e., the most generally projected climate variables), but might require input variables such as soil temperature, in-canopy net radiation or leaf wetness. Here, we use a stochastic weather and a re-sampling procedure for producing site-specific hourly weather data from regional climate change scenarios for 2050 in Switzerland. The climate change scenarios were derived from multi-model projections and provide probabilistic information on future regional changes in temperature and precipitation. Hourly temperature, precipitation and radiation data were produced by first generating daily weather data for these climate scenarios and then using a nearest neighbor re-sampling approach for creating realistic diurnal cycles. These hourly weather time series were then used for modeling important phases in the lifecycle of codling moth, the major insect pest in apple orchards worldwide. First results indicate a shift in the occurrence and duration of phases relevant for pest disease control for projected as compared to current climate (e.g. the flight of the codling moth starts about ten days earlier in future climate), continuing an already observed trend towards more favorable conditions for this insect during the last 20 years.

  20. Climate Twins - a tool to explore future climate impacts by assessing real world conditions: Exploration principles, underlying data, similarity conditions and uncertainty ranges

    Science.gov (United States)

    Loibl, Wolfgang; Peters-Anders, Jan; Züger, Johann

    2010-05-01

    To achieve public awareness and thorough understanding about expected climate changes and their future implications, ways have to be found to communicate model outputs to the public in a scientifically sound and easily understandable way. The newly developed Climate Twins tool tries to fulfil these requirements via an intuitively usable web application, which compares spatial patterns of current climate with future climate patterns, derived from regional climate model results. To get a picture of the implications of future climate in an area of interest, users may click on a certain location within an interactive map with underlying future climate information. A second map depicts the matching Climate Twin areas according to current climate conditions. In this way scientific output can be communicated to the public which allows for experiencing climate change through comparison with well-known real world conditions. To identify climatic coincidence seems to be a simple exercise, but the accuracy and applicability of the similarity identification depends very much on the selection of climate indicators, similarity conditions and uncertainty ranges. Too many indicators representing various climate characteristics and too narrow uncertainty ranges will judge little or no area as regions with similar climate, while too little indicators and too wide uncertainty ranges will address too large regions as those with similar climate which may not be correct. Similarity cannot be just explored by comparing mean values or by calculating correlation coefficients. As climate change triggers an alteration of various indicators, like maxima, minima, variation magnitude, frequency of extreme events etc., the identification of appropriate similarity conditions is a crucial question to be solved. For Climate Twins identification, it is necessary to find a right balance of indicators, similarity conditions and uncertainty ranges, unless the results will be too vague conducting a

  1. Vadose zone lag time and potential 21st century climate change effects on spatially distributed groundwater recharge in the semi-arid Nebraska Sand Hills

    Science.gov (United States)

    Rossman, N. R.; Zlotnik, V. A.; Rowe, C. M.; Szilagyi, J.

    2014-11-01

    Deep drainage of water below plant root zones (potential groundwater recharge) will become groundwater recharge (GR) after a delay (or lag time) in which soil moisture traverses the vadose zone before reaching the water table. Depending on the thickness of the vadose zone, the magnitude of deep drainage, and soil hydraulic properties, lag times will vary broadly, exceeding decades to centuries in semi-arid and arid environments. Yet, studies of future climate change impacts to GR have typically avoided focusing on impacts beyond 100 years and often neglect to consider lag effects caused by the vadose zone. We investigate the effects of vadose zone lag time and potential 21st century climate change on the spatial distribution and timing of GR throughout the semi-arid Nebraska Sand Hills (NSH) region (∼50,000 km2). We propose a simple and rapid quantitative approach for assessment of the groundwater system response time to changes in climate. Understanding of such effects is needed for groundwater modeling, analysis of climate change impacts on groundwater, and the effective management and sustainability of future water resources. Lag time estimates are made using the pressure-based vertical velocity of soil moisture changes, equivalent to a kinematic wave approximation of Richards' equation. The underlying assumptions (unit hydraulic gradient and relatively slow changes in climate) are supported by observations in the High Plains aquifer region, encompassing the NSH. The analysis relies on four sources of input data, including: Spatially distributed high resolution (1.1-km) GR rates (as the difference in 2000-2009 mean precipitation and evapotranspiration-estimated using a novel MODIS-based approach); thickness of the vadose zone-based on 30-m digital elevation models of the land surface and water table elevations; statistically downscaled estimates of future (2010-2099) potential GR rates from two hydroclimate model projections (WRCP CMIP3) with opposing GR

  2. Causes of early Holocene desertification in arid central Asia

    Energy Technology Data Exchange (ETDEWEB)

    Jin, Liya [Lanzhou University, Key Laboratory of Western China' s Environmental System, Lanzhou, Gansu (China); University of Kiel, Institute of Geosciences, Kiel (Germany); Chen, Fahu [Lanzhou University, Key Laboratory of Western China' s Environmental System, Lanzhou, Gansu (China); Morrill, Carrie [University of Colorado, Cooperative Institute for Research in Environmental Sciences, Boulder, CO (United States); NOAA' s National Climatic Data Center, Paleoclimatology Branch, Boulder, CO (United States); Otto-Bliesner, Bette L.; Rosenbloom, Nan [National Center for Atmospheric Research, Climate and Global Dynamics Division, Boulder, CO (United States)

    2012-04-15

    Paleoclimate records of effective moisture (precipitation minus evaporation, or P-E) show a dry (low effective moisture) period in mid-latitude arid/semi-arid central Asia during the early Holocene (11,000-8,000 years ago) relative to the middle and late Holocene, in contrast to evidence for greater-than-present precipitation at the same time in the south and east Asian monsoonal areas. To investigate the spatial differences in climate response over mid-latitude central Asia and monsoonal Asia we conducted a series of simulations with the Community Climate System Model version 3 coupled climate model for the early, middle and late Holocene. The simulations test the climatic impact of all important forcings for the early Holocene, including changes in orbital parameters, the presence of the remnant Laurentide ice sheet and deglacial freshening of the North Atlantic. Model results clearly show the early Holocene patterns indicated by proxy records, including both the decreased effective moisture in arid central Asia, which occurs in the model primarily during the winter months, and the increase in summer monsoon precipitation in south and east Asia. The model results suggest that dry conditions in the early Holocene in central Asia are closely related to decreased water vapor advection due to reduced westerly wind speed and less evaporation upstream from the Mediterranean, Black, and Caspian Seas in boreal winter. As an extra forcing to the early Holocene climate system, the Laurentide ice sheet and meltwater fluxes have a substantial cooling effect over high latitudes, especially just over and downstream of the ice sheets, but contribute only to a small degree to the early Holocene aridity in central Asia. Instead, most of the effective moisture signal can be explained by orbital forcing decreasing the early Holocene latitudinal temperature gradient and wintertime surface temperature. We find little evidence for regional subsidence related to a stronger summer Asian

  3. Diverging Responses of Tropical Andean Biomes under Future Climate Conditions

    Science.gov (United States)

    Tovar, Carolina; Arnillas, Carlos Alberto; Cuesta, Francisco; Buytaert, Wouter

    2013-01-01

    Observations and projections for mountain regions show a strong tendency towards upslope displacement of their biomes under future climate conditions. Because of their climatic and topographic heterogeneity, a more complex response is expected for biodiversity hotspots such as tropical mountain regions. This study analyzes potential changes in the distribution of biomes in the Tropical Andes and identifies target areas for conservation. Biome distribution models were developed using logistic regressions. These models were then coupled to an ensemble of 8 global climate models to project future distribution of the Andean biomes and their uncertainties. We analysed projected changes in extent and elevational range and identified regions most prone to change. Our results show a heterogeneous response to climate change. Although the wetter biomes exhibit an upslope displacement of both the upper and the lower boundaries as expected, most dry biomes tend to show downslope expansion. Despite important losses being projected for several biomes, projections suggest that between 74.8% and 83.1% of the current total Tropical Andes will remain stable, depending on the emission scenario and time horizon. Between 3.3% and 7.6% of the study area is projected to change, mostly towards an increase in vertical structure. For the remaining area (13.1%–17.4%), there is no agreement between model projections. These results challenge the common believe that climate change will lead to an upslope displacement of biome boundaries in mountain regions. Instead, our models project diverging responses, including downslope expansion and large areas projected to remain stable. Lastly, a significant part of the area expected to change is already affected by land use changes, which has important implications for management. This, and the inclusion of a comprehensive uncertainty analysis, will help to inform conservation strategies in the Tropical Andes, and to guide similar assessments for

  4. Agronomic Importance of First Development of Chickpea (Cicer arietinum L.) Under Semi-arid Conditions: I. Effect of Powder Humic Acid

    OpenAIRE

    N. Bayraktar; Ulukan, H; N. Kocak

    2012-01-01

    Due to slow growth and weakness of the first development of chickpea (Cicer arietinum L.) plant could not combatted with weeds and easily get caught up by Ascochyta blight (Ascochyta rabiei (Pass) Labr.) disease; esp. under the late sowing and semi-arid conditions, due to effect of biotic and abiotic stress factors, significant yield losses could be arised. To be able to avoid from them is only possible to accelerate the first development of this crop. So, one of the best solutions is to use ...

  5. Water use efficiency and crop water balance of rainfed wheat in a semi-arid environment: sensitivity of future changes to projected climate changes and soil type

    Science.gov (United States)

    Yang, Yanmin; Liu, De Li; Anwar, Muhuddin Rajin; O'Leary, Garry; Macadam, Ian; Yang, Yonghui

    2016-02-01

    Wheat production is expected to be affected by climate change through changing components of the crop water balance such as rainfall, evapotranspiration (ET), runoff and drainage. We used the Agricultural Production Systems Simulator (APSIM)-wheat model to simulate the potential impact of climate change on field water balance, ET and water use efficiency (WUE) under the SRES A2 emissions scenario. We ran APSIM with daily climate data statistically downscaled from 18 Global Circulation Models (GCMs). Twelve soil types of varying plant available water holding capacity (PAWC) at six sites across semi-arid southeastern Australia were considered. Biases in the GCM-simulated climate data were bias-corrected against observations for the 1961-1999 baseline period. However, biases in the APSIM output data relative to APSIM simulations forced with climate observations remained. A secondary bias correction was therefore performed on the APSIM outputs. Bias-corrected APSIM outputs for a future period (2021-2040) were compared with APSIM outputs generated using observations for the baseline period to obtain future changes. The results show that effective rainfall was decreased over all sites due to decreased growing season rainfall. ET was decreased through reduced soil evaporation and crop transpiration. There were no significant changes in runoff at any site. The variation in deep drainage between sites was much greater than for runoff, ranging from less than a few millimetres at the drier sites to over 100 mm at the wetter. However, in general, the averaged drainage over different soil types were not significantly different between the baseline (1961-1999) and future period of 2021-2040 ( P > 0.05). For the wetter sites, the variations in the future changes in drainage and runoff between the 18 GCMs were larger than those of the drier sites. At the dry sites, the variation in drainage decreased as PAWC increased. Overall, water use efficiency based on transpiration (WUE

  6. Sources and transport of algae and nutrients in a Californian river in a semi-arid climate

    Science.gov (United States)

    Ohte, N.; Dahlgren, R.A.; Silva, S.R.; Kendall, C.; Kratzer, C.R.; Doctor, D.H.

    2007-01-01

    1. To elucidate factors contributing to dissolved oxygen (DO) depletion in the Stockton Deep Water Ship Channel in the lower San Joaquin River, spatial and temporal changes in algae and nutrient concentrations were investigated in relation to flow regime under the semiarid climate conditions. 2. Chlorophyll-a (chl-a) concentration and loads indicated that most algal biomass was generated by in-stream growth in the main stem of the river. The addition of algae from tributaries and drains was small (c.15% of total chl-a load), even though high concentrations of chl-a were measured in some source waters. 3. Nitrate and soluble-reactive phosphorus (SRP) were available in excess as a nutrient source for algae. Although nitrate and SRP from upstream tributaries contributed (16.9% of total nitrate load and 10.8% of total SRP load), nutrients derived from agriculture and other sources in the middle and lower river reaches were mostly responsible (20.2% for nitrate and 48.0% for SRP) for maintaining high nitrate and SRP concentrations in the main stem. 4. A reduction in nutrient discharge would attenuate the algal blooms that accelerate DO depletion in the Stockton Deep Water Ship Channel. The N : P ratio, in the main stem suggests that SRP reduction would be a more viable option for algae reduction than nitrogen reduction. 5. Very high algal growth rates in the main stem suggest that reducing the algal seed source in upstream areas would also be an effective strategy. ?? 2007 Blackwell Publishing Ltd.

  7. Simulating the hydrological response of a closed catchment-lake system to recent climate and land-use changes in semi-arid Mediterranean environment

    Science.gov (United States)

    Niedda, Marcello; Pirastru, Mario; Castellini, Mirko; Giadrossich, Filippo

    2014-09-01

    Lake water levels are sensitive sentinels of changes in the climate and landscape of the broader lake catchment. This means that lakes can be useful for quantifying the effects of these changes on the water yield of a catchment. This study presents a water balance model of a closed catchment-lake system in the semi-arid Mediterranean climate over the last 85 years, with the objective to understand the influence of precipitation change and the conversion from Mediterranean maquis to pasture. Deforestation alters the balance between evapotranspiration and canopy interception, and causes the rapid decay of soil hydrological properties, thus changing the mechanisms of runoff generation. The overall impact of these changes on the water yield has been evaluated for the catchment of the lake. A physically based rainfall-runoff model, combined with the energy budget method for estimating lake evaporation, were used for the lake water balance model. The calibration was carried out with the continuous measurements taken during the period 2008-2013. The reliability was evaluated with the historical lake levels between 1929 and 2008. Simulation errors were small despite the high sensitivity of the water balance model to precipitation, which in the historical period was that of a non-local station. The simulation results show that the balance was influenced by a combination of climate and land-use changes. The 23% decrease in precipitation observed in the last 50-years has resulted in a 72% decrease in average streamflow. The contemporaneous deforestation in 18% of the catchment area resulted in a 13% decrease in streamflow. The main mechanism of runoff generation under the maquis cover was saturated subsurface-flow. At hillslope scale this can eliminate the surface runoff, giving the impression that the water yield is lower than that of deforested hillslopes. However, at the basin scale the effect can also be reversed. The reduction in soil hydraulic conductivity and porosity

  8. Response of Groundwater to Climate Change under Extreme Climate Conditions in North China Plain

    Institute of Scientific and Technical Information of China (English)

    Ying Zhang; Jincui Wang; Jihong Jing; Jichao Sun

    2014-01-01

    The North China Plain (NCP) is one of the water shortage areas of China. Lack of water resources restricted the economic and social development of North China area and resulted in deterio-ration of ecosystem and natural environment. Influenced by the climate change and human activities, the water circulation of NCP was largely changed and the crisis of water resources was aggravated. Therefore, it is important to study the features of the extreme climate and the response mechanism of groundwater to climate change. We analyzed the trend of climate change and extreme climate features in the past 60 years based on the monitoring data of meteorological stations. And then the response characteristics of groundwater to climate change were discussed. The average temperature of NCP was in an obviously upward trend. The overall precipitation variation was in a downward trend. The cli-mate change in this area showed a warming-drying trend. The intensity of extreme precipitation dis-played a trend of declining and then increasing from north to south as well as declining from eastern coastal plain to the piedmont plain. Grey correlation degree analysis indicated that groundwater depth had a close relationship with precipitation and human activities in NCP. The response of groundwater level to precipitation differed from the piedmont alluvial-pluvial plain to the coastal plain. The response was more obvious in the coastal plain than the piedmont alluvial-pluvial plain and the middle plain. The precipitation influenced the groundwater depth both directly and indirectly. Under the condition of extreme precipitation, the impact would aggravate, in the forms of rapid or lag raise of groundwater levels.

  9. Using ground- and satellite-based measurements and models to quantify response to multiple disturbances and climate change in South African semi-arid ecosystems

    Science.gov (United States)

    Falge, Eva; Brümmer, Christian; Schmullius, Christiane; Scholes, Robert; Twine, Wayne; Mudau, Azwitamisi; Midgley, Guy; Hickler, Thomas; Bradshaw, Karen; Lück, Wolfgang; Thiel-Clemen, Thomas; du Toit, Justin; Sankaran, Vaith; Kutsch, Werner

    2016-04-01

    Sub-Saharan Africa currently experiences significant changes in shrubland, savanna and mixed woodland ecosystems driving degradation, affecting fire frequency and water availability, and eventually fueling climate change. The project 'Adaptive Resilience of Southern African Ecosystems' (ARS AfricaE) conducts research and develops scenarios of ecosystem development under climate change, for management support in conservation or for planning rural area development. For a network of research clusters along an aridity gradient in South Africa, we measure greenhouse gas exchange, ecosystem structure and eco-physiological properties as affected by land use change at paired sites with natural and altered vegetation. We set up dynamic vegetation models and individual-based models to predict ecosystem dynamics under (post) disturbance managements. We monitor vegetation amount and heterogeneity using remotely sensed images and aerial photography over several decades to examine time series of land cover change. Finally, we investigate livelihood strategies with focus on carbon balance components to develop sustainable management strategies for disturbed ecosystems and land use change. Emphasis is given on validation of estimates obtained from eddy covariance, model approaches and satellite derivations. We envision our methodological approach on a network of research clusters a valuable means to investigate potential linkages to concepts of adaptive resilience.

  10. A model for simulating the response of runoff from the mountainous watersheds of inland river basins in the arid area of northwest China to climatic changes

    Institute of Scientific and Technical Information of China (English)

    康尔泗; 程国栋; 蓝永超; 金会军

    1999-01-01

    A model for simulating the response of monthly runoff from the mountainous watersheds to climatic changes is developed.The model is based on the modifications to the HBV runoff model, and therefore represents the characteristics and runoff generation processes of inland river basins in the arid area of northwest China. Taking the mountainous watershed of an inland river, the Heihe River originating from the Qilian Mountains and running through the Hexi Corridor as an example, the monthly runoff changes under different climate scenarios are simulated. The simulation indicates that, during the years from 1994 to 2030, if the annual mean air temperature increases by 0.5℃, and precipitation keeps unchanged, then the runoff of May and October will increase because of the increase of the snow melt runoff, but the runoff of July and August will decrease to some extent because of the increase of evaporation, and as a result, the annual runoff will decrease by 4%. If the precipitation still keeps unchanged, an

  11. Response to climate change of different tree species and NDVI variation since 1923 in the middle arid region of Ningxia, China

    Institute of Scientific and Technical Information of China (English)

    YaJun Wang; RuiJie Lu; YuZhen Ma; HongWei Meng; ShangYu Gao

    2014-01-01

    The normalized difference vegetation index (NDVI) is used extensively to describe vegetation cover and ecological environ-ment change. The purpose of this study was to contrast the response of different tree species growing in the same habitat to climate change and retrieve past NDVI using tree-ring width data from tree cores collected from the transitional zone of Pinus tabulaeformis and Picea crassifolia in the Luoshan Mountains in the middle arid region of Ningxia. Correlation analysis indi-cated that radial growth of P. tabulaeformis is more sensitive to precipitation and temperature change than that of P. crassifolia. Natural factors such as water availability and heat at this elevation are more suited to the growth of P. crassifolia, and are more advantageous to its renewal and succession. P. crassifolia is probably the better of the two species for protecting the forest ecosystem and conserving water in the Luoshan desertification area. Ring width of P. crassifolia correlates significantly with average NDVI for April-May (r=0.641, p<0.01), and both of them are influenced positively by precipitation in April-May. The reconstructed NDVI for 1923-2007 shows the relatively low vegetation cover occurred in the 1920s-1930s, the 1960s-1970s, and the early 21st century. The reconstructed NDVI better reflected the drought climate in the study area.

  12. A Dynamic, Multivariate Sustainability Measure for Robust Analysis of Water Management under Climate and Demand Uncertainty in an Arid Environment

    OpenAIRE

    Christian Hunter; Jorge Gironás; Diogo Bolster; Christos A. Karavitis

    2015-01-01

    Considering water resource scarcity and uncertainty in climate and demand futures, decision-makers require techniques for sustainability analysis in resource management. Through unclear definitions of “sustainability”, however, traditional indices for resource evaluation propose options of limited flexibility by adopting static climate and demand scenarios, limiting analysis variables to a particular water-use group and time. This work proposes a robust, multivariate, dynamic sustainability e...

  13. A persistent Holocene wetting trend in arid central Asia, with wettest conditions in the late Holocene, revealed by multi-proxy analyses of loess-paleosol sequences in Xinjiang, China

    Science.gov (United States)

    Chen, Fahu; Jia, Jia; Chen, Jianhui; Li, Guoqiang; Zhang, Xiaojian; Xie, Haichao; Xia, Dunsheng; Huang, Wei; An, Chengbang

    2016-08-01

    There are significant differences in the interpretation of the moisture (precipitation) history of arid central Asia (ACA) during the Holocene, as inferred on one hand from speleothem oxygen isotope records, and on the other from lake sediments. Here we present the results of measurements of climatically-sensitive magnetic properties and soil color from four well-dated loess-paleosol sequences from the northern slopes of the Tienshan Mountains and the Yili River valley, Xinjiang, China, in the core area of ACA. Our results demonstrate that the characteristic Holocene paleosol, indicating relatively moist conditions, generally formed after ∼6 ka (1 ka = 1000 cal yr BP) in the study region, and that the accumulation of unweathered loess prevailed during the early Holocene, indicating a dry climate at that time. The magnetic proxies further reveal a trend of generally increasing moisture since the Last Glacial Maximum, with the wettest climate occurring during the late Holocene. This trend of increasing moisture during the Holocene is representative of the Xinjiang region and possibly of the whole of the core area of ACA, and is in marked contrast both to the mid-Holocene moisture maximum observed in the East Asian summer monsoon region and to the general decrease in the strength of the Indian summer monsoon since the early Holocene. Our findings are supported by the results of a climate simulation which indicate a trend of increasing summer and winter precipitation during the Holocene in the core area of ACA, caused mainly by an increase in the strength of the westerlies effected by an increasing latitudinal insolation gradient and by a negative trend of the Arctic Oscillation (AO) or North Atlantic Oscillation (NAO).

  14. Planetary boundary layer energetics simulated from a regional climate model over Europe for present climate and climate change conditions

    Science.gov (United States)

    Sánchez, E.; Yagüe, C.; Gaertner, M. A.

    2007-01-01

    This paper presents a description of the planetary boundary layer (PBL) for current (1960-1990) and future (2070-2100) climate periods as obtained from a regional climate model (RCM) centered on the Mediterranean basin. Vertically integrated turbulent kinetic energy (TKEZ) and boundary layer height (z i ) are used to describe PBL energetics. Present climate shows a TKEZ annual cycle with a clear summer maximum for southern regions, while northern regions of Europe exhibit a smoother or even a lack of cycle. Future climate conditions exhibit a similar behaviour, with an increase in the summer maximum peaks. A detailed analysis of summer surface climate change energetics over land shows an increased Bowen ratio and decreases in the evaporative fraction. The enhanced sensible heat flux responsible for these results causes an energy surplus inside the PBL, resulting in increased convective activity and corresponding TKEZ. These results are consistent with temperature increases obtained by several other model simulations, and also indicate that changes in the turbulent transport from the PBL to the free troposphere can affect atmospheric circulations.

  15. Projection of climatic suitability for Aedes albopictus Skuse (Culicidae) in Europe under climate change conditions

    Science.gov (United States)

    Fischer, Dominik; Thomas, Stephanie Margarete; Niemitz, Franziska; Reineking, Björn; Beierkuhnlein, Carl

    2011-07-01

    During the last decades the disease vector Aedes albopictus ( Ae. albopictus) has rapidly spread around the globe. The spread of this species raises serious public health concerns. Here, we model the present distribution and the future climatic suitability of Europe for this vector in the face of climate change. In order to achieve the most realistic current prediction and future projection, we compare the performance of four different modelling approaches, differentiated by the selection of climate variables (based on expert knowledge vs. statistical criteria) and by the geographical range of presence records (native range vs. global range). First, models of the native and global range were built with MaxEnt and were either based on (1) statistically selected climatic input variables or (2) input variables selected with expert knowledge from the literature. Native models show high model performance (AUC: 0.91-0.94) for the native range, but do not predict the European distribution well (AUC: 0.70-0.72). Models based on the global distribution of the species, however, were able to identify all regions where Ae. albopictus is currently established, including Europe (AUC: 0.89-0.91). In a second step, the modelled bioclimatic envelope of the global range was projected to future climatic conditions in Europe using two emission scenarios implemented in the regional climate model COSMO-CLM for three time periods 2011-2040, 2041-2070, and 2071-2100. For both global-driven models, the results indicate that climatically suitable areas for the establishment of Ae. albopictus will increase in western and central Europe already in 2011-2040 and with a temporal delay in eastern Europe. On the other hand, a decline in climatically suitable areas in southern Europe is pronounced in the Expert knowledge based model. Our projections appear unaffected by non-analogue climate, as this is not detected by Multivariate Environmental Similarity Surface analysis. The generated risk maps

  16. Assessment of climate change downscaling and non-stationarity on the spatial pattern of a mangrove ecosystem in an arid coastal region of southern Iran

    Science.gov (United States)

    Etemadi, Halimeh; Samadi, S. Zahra; Sharifikia, Mohammad; Smoak, Joseph M.

    2015-07-01

    Mangrove wetlands exist in the transition zone between terrestrial and marine environments and have remarkable ecological and socio-economic value. This study uses climate change downscaling to address the question of non-stationarity influences on mangrove variations (expansion and contraction) within an arid coastal region. Our two-step approach includes downscaling models and uncertainty assessment, followed by a non-stationary and trend procedure using the Extreme Value Analysis (extRemes code). The Long Ashton Research Station Weather Generator (LARS-WG) model along with two different general circulation model (GCMs) (MIRH and HadCM3) were used to downscale climatic variables during current (1968-2011) and future (2011-2030, 2045-2065, and 2080-2099) periods. Parametric and non-parametric bootstrapping uncertainty tests demonstrated that the LARS-WGS model skillfully downscaled climatic variables at the 95 % significance level. Downscaling results using MIHR model show that minimum and maximum temperatures will increase in the future (2011-2030, 2045-2065, and 2080-2099) during winter and summer in a range of +4.21 and +4.7 °C, and +3.62 and +3.55 °C, respectively. HadCM3 analysis also revealed an increase in minimum (˜+3.03 °C) and maximum (˜+3.3 °C) temperatures during wet and dry seasons. In addition, we examined how much mangrove area has changed during the past decades and, thus, if climate change non-stationarity impacts mangrove ecosystems. Our results using remote sensing techniques and the non-parametric Mann-Whitney two-sample test indicated a sharp decline in mangrove area during 1972,1987, and 1997 periods (p value = 0.002). Non-stationary assessment using the generalized extreme value (GEV) distributions by including mangrove area as a covariate further indicated that the null hypothesis of the stationary climate (no trend) should be rejected due to the very low p values for precipitation (p value = 0.0027), minimum (p value = 0

  17. Evaluation of an extreme-condition-inverse calibration remote sensing model for mapping energy balance fluxes in arid riparian areas

    Directory of Open Access Journals (Sweden)

    S.-H. Hong

    2014-12-01

    Full Text Available Accurate information on the distribution of the surface energy balance components in arid riparian areas is needed for sustainable management of water resources as well as for a better understanding of water and heat exchange processes between the land surface and the atmosphere. Since the spatial and temporal distributions of these fluxes over large areas are difficult to determine from ground measurements alone, their prediction from remote sensing data is very attractive as it enables large area coverage and a high repetition rate. In this study the Surface Energy Balance Algorithm for Land (SEBAL was used to estimate all the energy balance components in the arid riparian areas of the Middle Rio Grande Basin (New Mexico, San Pedro Basin (Arizona, and Owens Valley (California. We compare instantaneous and daily SEBAL fluxes derived from Landsat TM images to surface-based measurements with eddy covariance flux towers. This study presents evidence that SEBAL yields reliable estimates for actual evapotranspiration rates in riparian areas of the southwestern United States. The great strength of the SEBAL method is its internal calibration procedure that eliminates most of the bias in latent heat flux at the expense of increased bias in sensible heat flux.

  18. Estimating sunshine duration from other climatic data by artificial neural network for ET0 estimation in an arid environment

    Science.gov (United States)

    Rahimikhoob, Ali

    2014-10-01

    Sunshine duration data are desirable for calculating daily solar radiation ( R s) and subsequent reference evapotranspiration (ET0) using the Penman-Monteith (PM) method. In the absence of measured R s data, the Ångström equation has been recommended by the Food and Agriculture Organization (FAO) of the United Nations. This equation requires actual sunshine duration that is not commonly observed at many weather stations. This paper examines the potential for the use of artificial neural networks (ANNs) to estimate sunshine duration based on air temperature and humidity data under arid environment. This is important because these data are commonly available parameters. The impact of the estimated sunshine duration on estimation of R s and ET0 was also conducted. The four weather stations selected for this study are located in Sistan and Baluchestan Province (southeast of Iran). The study demonstrated that modelling of sunshine duration through the use of ANN technique made acceptable estimates. Models were compared using the determination coefficient ( R 2), the root mean square error (RMSE) and the mean bias error (MBE). Average R 2, RMSE and MBE for the comparison between measured and estimated sunshine duration were calculated resulting 0.81, 6.3 % and 0.1 %, respectively. Our analyses also demonstrate that the difference between the measured and estimated sunshine duration has less effect on the estimated R s and ET0 by using Ångström and FAO-PM equations, respectively.

  19. Subtropical Modern Greenhouse Cucumber Canopy Transpiration Under Summer Climate Condition

    Institute of Scientific and Technical Information of China (English)

    LUO Wei-hong; WANG Xiao-han; DING Wei-min; CHEN Yu-qing; DAI Jian-feng

    2002-01-01

    Greenhouse canopy transpiration not only has effects on greenhouse air temperature and humidity, but also is important for determining the set-point of fertigation. In this study, Penman-Monteith equation was used to calculate the greenhouse cucumber canopy transpiration under summer climate condition.The effects of greenhouse environmental factors on canopy transpiration were analyzed based on the measurements of greenhouse microclimate factors and canopy transpiration. The results showed that Penman-Monteith equation was reliable and robust in estimating greenhouse cucumber canopy transpiration under summer climate condition. Greenhouse cucumber canopy transpiration rate increased linearly with the increase of net radiation and water vapor pressure deficit (VPD) above the canopy. But the maximum value of the canopy transpiration rate occurred at the same time as that of VPD whereas about two hours later than that of net radiation. Based on the results, it was concluded that in addition to radiation, air humidity should also be considered when determine the set-point of fertigation.

  20. Slarti: A boundary condition editor for a coupled climate model

    Science.gov (United States)

    Mickelson, S. A.; Jacob, R. L.; Pierrehumbert, R.

    2006-12-01

    One of the largest barriers to making climate models more flexible is the difficulty in creating new boundary conditions, especially for "deep time" paleoclimate cases where continents are in different positions. Climate models consist of several mutually-interacting component models and the boundary conditions must be consistent between them. We have developed a program called Slarti which uses a Graphical User Interface and a set of consistency rules to aid researchers in creating new, consistent, boundary condition files for the Fast Ocean Atmosphere Model (FOAM). Users can start from existing mask, topography, or bathymetry data or can build a "world" entirely from scratch (e.g. a single island continent). Once a case has been started, users can modify mask, vegetation, bathymetry, topography, and river flow fields by drawing new data through a "paint" interface. Users activate a synchronization button which goes through the fields to eliminate inconsistencies. When the changes are complete and save is selected, Slarti creates all the necessary files for an initial run of FOAM. The data is edited at the highest resolution (the ocean-land surface in FOAM) and then interpolated to the atmosphere resolution. Slarti was implemented in Java to maintain portability across platforms. We also relied heavily on Java Swing components to create the interface. This allowed us to create an object-oriented interface that could be used on many different systems. Since Slarti allows users to visualize their changes, they are able to see areas that may cause problems when the model is ran. Some examples would be lakes from the river flow field and narrow trenches within the bathymetry. Through different checks and options available through its interface, Slarti makes the process of creating new boundary conditions for FOAM easier and faster while reducing the chance for user errors.

  1. Scale-dependent isotope tracking of the continental water balance under wet and dry climate conditions

    International Nuclear Information System (INIS)

    Full text: Under a simple and ideal Rayleigh-rainout scenario the atmospheric moisture is depleted in the heavy isotope content commensurate with the loss of moisture by precipitation during a continental passage, following more-or- less a 'Meteoric Water Line' with a constant d-excess. The surface and sub-surface runoff on a basin or continental scale then obviously carries the integrated precipitation isotope signal, alas at times with a considerable time delay. Due to the eco-hydrological interactions at the land surface part of the incoming precipitation is reevaporated, either directly from open water bodies and canopy intercepted precipitation pools, from the topsoil layer or through the intermediary of plants as transpiration. The latter, i.e. the transpiration flux, returns the water essentially unfractionated to the atmosphere with the result that there is an apparent reduction in the degree of the Rayleigh rainout effect, which can be measured by comparison of the isotopic buildup in the atmospheric waters and of the runoff compared to the expected buildup based on the precipitation amounts. This has been exemplified for the conditions of the tropical rain forest in the Amazon. As is well known, evaporation from open water surfaces returns a fractionated flux, where the residual surface waters are enriched and the evaporated moisture depleted in the heavy isotopes of Hydrogen and Oxygen, following an 'Evaporation Line' rather than the 'Meteoric Water Line'. Under such circumstances the degree of recycling of the moisture due to this mechanism can be quantified by recording the change in the d-excess parameter between the precipitation and the runoff, on the one hand, and the downwind atmospheric waters, on the other hand. All these examples are taken from rather humid climates where the evaporative buildup is not the dominant balance factor and where, moreover, as the geographic scale increases the effect of the evaporative signature of the watershed

  2. Effect of water stress on growth, water consumption and yield of silage maize under flood irrigation in a semi-arid climate of Tadla (Morocco

    Directory of Open Access Journals (Sweden)

    Bouazzama, B.

    2012-01-01

    Full Text Available The field study of crop response to water stress is important to maximize yield and improve agricultural water use efficiency in areas where water resources are limited. This study was carried out during two growing periods in 2009 and 2010 in order to study the effect of water stress on crop growth, water consumption and dry matter yield of silage maize (Zea mays L. supplied with flood irrigation under the semi-arid climate of Tadla in Morocco. Four to five irrigation treatments were applied at the rates of 100, 80, 60, 40 and 20% crop evapotranspiration (ETc of maize. Soil water status, crop growth, leaf area index and above-ground biomass were measured. Results showed that irrigation deficit affected plant height growth, accelerated the senescence of the leaves and reduced the leaf area index. The maximum values of this parameter reached at flowering under the full irrigation treatment (100% ETc were 5.1 and 4.8 in 2009 and 2010, respectively. Dry matter yields varied from 5.3 t·ha-1 under T4 (40% ETc to 16.4 t·ha-1 under T1 (100% ETc in 2009, whereas in 2010, it oscillated between 3.9 t·ha-1 under T5 (20% ETc to 12.5 t·ha-1 under T1 (100% ETc. The establishment of the water budget by growth phase showed that the water use efficiency was higher during the linear phase of growth. Water use efficiency calculated at harvest varied between 2.99 kg·m-3 under T1 to 1.84 kg·m-3 under T5. The actual evapotranspiration under T1 (100% ETc was 478 mm and 463 mm in 2009 and 2010, respectively. Using the averaged values of the two years, linear relationships were evaluated between dry matter yield and water consumption ETa. The yield response factor (Ky for the silage maize for both growth seasons was 1.12. Under the Tadla semi-arid climate, it is proposed that silage maize should be irrigated as a priority before other crops with a Ky lower than 1.12. It is also recommended that, under limited water supplies, irrigation be applied during the linear

  3. Field investigation of the quality of fresh and aged leachates from selected landfills receiving e-waste in an arid climate

    International Nuclear Information System (INIS)

    elevated contaminant levels to e-waste, we do not recommend continued disposal of e-waste in old landfills that were not originally designed to contain leachates. The survey also revealed temporal variation in the electrical conductivity and concentrations of As, Cd and Pb present in leachates of landfills in arid Mediterranean climates. These results are consistent with the marked variations in rainfall patterns observed for such climates. The solute concentration (EC and other ions including As, Cd and Pb) declines in the leachates during wet winter months (June to September), in contrast to tropical countries where such changes are observed during wet summer months

  4. Sales down due to particularly mild climatic conditions

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2007-07-01

    Paris, 27 July 2007 - For the six months to 30 June 2007, Gaz de France's consolidated sales amounted to euro 13,778 million, down 11 per cent compared to the same period in 2006. This performance continues the trend seen over the first quarter of 2007 and in particular reflects the continuation into the second quarter of the climatic factors that affected the start of the year: an exceptionally warm 2006/2007 winter, followed by a spring season with particularly high temperatures. The average temperature of the first half of 2007 corresponds to a heat risk of less than one per cent, meaning that the probability of such a temperature taking place is less than one per cent. Over the first half of the year, volumes distributed in France were down by 25 TWh compared to a comparable period with average weather conditions, whereas in 2006 they were 15 TWh above average. The impact of the weather had similar effects outside of France. Under average weather conditions, the downturn in Group sales was limited to only 0.8 per cent mainly due to market conditions made difficult by the climate, leading to a lower level of gas production and arbitrage activities. Over the first six months of 2007, the Group sought to: - Continue to strengthen its international presence, currently with euro 5,602 million in sales outside of France. The percentage of sales generated outside of France represented 41 per cent of the Group total at the end of June 2007 and increased by 4 percentage points between the first half of 2006 and the first half of 2007. - Prepare for the deregulation of the markets on 1 July 2007 and a new commercial policy for retail customers that has been built around multi-energy and multi-service market offerings. - Create a new subsidiary for the distribution, a process which will be effective at the end of the year as announced. In spite of this unfavourable context, the Group maintains the financial objective for 2007 presented with the 2006 accounts: &apos

  5. Sales down due to particularly mild climatic conditions

    International Nuclear Information System (INIS)

    Paris, 27 July 2007 - For the six months to 30 June 2007, Gaz de France's consolidated sales amounted to euro 13,778 million, down 11 per cent compared to the same period in 2006. This performance continues the trend seen over the first quarter of 2007 and in particular reflects the continuation into the second quarter of the climatic factors that affected the start of the year: an exceptionally warm 2006/2007 winter, followed by a spring season with particularly high temperatures. The average temperature of the first half of 2007 corresponds to a heat risk of less than one per cent, meaning that the probability of such a temperature taking place is less than one per cent. Over the first half of the year, volumes distributed in France were down by 25 TWh compared to a comparable period with average weather conditions, whereas in 2006 they were 15 TWh above average. The impact of the weather had similar effects outside of France. Under average weather conditions, the downturn in Group sales was limited to only 0.8 per cent mainly due to market conditions made difficult by the climate, leading to a lower level of gas production and arbitrage activities. Over the first six months of 2007, the Group sought to: - Continue to strengthen its international presence, currently with euro 5,602 million in sales outside of France. The percentage of sales generated outside of France represented 41 per cent of the Group total at the end of June 2007 and increased by 4 percentage points between the first half of 2006 and the first half of 2007. - Prepare for the deregulation of the markets on 1 July 2007 and a new commercial policy for retail customers that has been built around multi-energy and multi-service market offerings. - Create a new subsidiary for the distribution, a process which will be effective at the end of the year as announced. In spite of this unfavourable context, the Group maintains the financial objective for 2007 presented with the 2006 accounts: '2007 will

  6. Effects of Drip System Uniformity and Irrigation Amount on Water and Salt Distributions in Soil Under Arid Conditions

    Institute of Scientific and Technical Information of China (English)

    GUAN Hong-jie; LI Jiu-sheng; LI Yan-feng

    2013-01-01

    The dynamics of water and salt in soil were monitored in the 2010 and 2011 growing seasons of cotton to evaluate the salinity risk of soil under drip irrigation in arid environments for different management practices of drip system uniformity and irrigation amount. In the experiments, three Christiansen uniformity coefficients (CU) of approximately 65, 80, and 95%(referred to as low, medium, and high uniformity, respectively) and three irrigation amounts of 50, 75, and 100%of full irrigation were used. The distribution of the soil water content and bulk electrical conductivity (ECb) was monitored continuously with approximately equally spaced frequency domain reflectometry (FDR) sensors located along a dripline. Gravimetric samples of soil were collected regularly to determine the distribution of soil salinity. A great fluctuation in CU of water content and ECb at 60 cm depth was observed for the low uniformity treatment during the irrigation season, while a relatively stable variation pattern was observed for the high uniformity treatment. The ECb CU was substantially lower than the water content CU and its value was greatly related to the water content CU and the initial ECb CU. The spatial variation of seasonal mean soil water content and seasonal mean soil bulk electrical conductivity showed a high dependence on the variation pattern of emitter discharge rate along a dripline for the low and medium uniformity treatments. A greater irrigation amount produced a significantly lower soil salinity at the end of the irrigation season, while the influence of the system uniformity on the soil salinity was insignificant at a probability level of 0.1. In arid regions, the determination of the target drip irrigation system uniformity should consider the potential salinity risk of soil caused by nonuniform water application as the influence of the system uniformity on the distribution of the soil salinity was progressively strengthened during the growing season of crop.

  7. On the Role of Hyper-arid Regions within the Virtual Water Trade Network

    Science.gov (United States)

    Aggrey, James; Alshamsi, Aamena; Molini, Annalisa

    2016-04-01

    Climate change, economic development, and population growth are bound to increasingly impact global water resources, posing a significant threat to the sustainable development of arid regions, where water consumption highly exceeds the natural carrying capacity, population growth rate is high, and climate variability is going to impact both water consumption and availability. Virtual Water Trade (VWT) - i.e. the international trade network of water-intensive products - has been proposed as a possible solution to optimize the allocation of water resources on the global scale. By increasing food availability and lowering food prices it may in fact help the rapid development of water-scarce regions. The structure of the VWT network has been analyzed by a number of authors both in connection with trade policies, socioeconomic constrains and agricultural efficiency. However a systematic analysis of the structure and the dynamics of the VWT network conditional to aridity, climatic forcing and energy availability, is still missing. Our goal is hence to analyze the role of arid and hyper-arid regions within the VWN under diverse climatic, demographic, and energy constraints with an aim to contribute to the ongoing Energy-Water-Food nexus discussion. In particular, we focus on the hyper-arid lands of the Arabian Peninsula, the role they play in the global network and the assessment of their specific criticalities, as reflected in the VWN resilience.

  8. Study on the glacier variation and its runoff responses in the arid region of Northwest China

    Institute of Scientific and Technical Information of China (English)

    刘潮海; 康尔泗; 刘时银; 陈建明; 刘宗香

    1999-01-01

    The glaciers in the arid region of Northwest China are viewed as an independent system, and glacier variation and mass balance fluctuation since the Little Ice Age and in the recent decades are estimated. Based on the estimation, the threshold time of glacier runoff against the backgrounds of the current and future varying climate conditions is simulated.

  9. Groundwater Management Policies for Maintaining Stream Flow Given Variable Climatic Conditions

    Science.gov (United States)

    Pohll, G.; Carroll, R. W.; Brozovic, N.

    2012-12-01

    Groundwater is an important resource to agriculture throughout the semi-arid United States, where farmers often supplement surface water diversions with groundwater pumping. Understanding the complex exchange over space and time between rivers and aquifers is important in developing management alternatives that are capable of preserving stream flow for habitat and increasing water deliveries downstream while minimizing lost crop production. Previous integrated hydrologic-economic models have generally assumed superposition of the impacts of groundwater pumping on the hydrologic system for analytical tractability. Although this assumption may be reasonable for some surface water-groundwater systems, in many systems the behavior diverges considerably from the linear assumption. We present analyses using an integrated hydrologic-economic model of surface water-groundwater interaction with nonlinear dynamics, developed for the Mason Valley area in Nevada. The study area has active water conflict between upstream and downstream water users, where groundwater pumping has an important impact on streamflow. The model replicates the movement of water throughout the coupled river and aquifer of the Walker River system and is used to analyze hypothetical tradeoffs between increasing streamflow at the basin outlet and meeting crop water demands for irrigation. The model is run from 1997 to 2006 to capture wet and dry climatic conditions, including a four year drought period in which groundwater pumping accounts for more than 50% of the irrigated water budget. Three alternate groundwater management policies are analyzed to compare economic performance (resulting from reductions in crop area due to reduced groundwater pumping) and hydrologic impact (in terms of increased stream discharge at the basin outlet). First, uniform pumping quotas are the simplest policy to implement and are modeled here as equal reductions in groundwater pumping for each stakeholder at a lumped field

  10. Host-parasite interactions under extreme climatic conditions

    Institute of Scientific and Technical Information of China (English)

    J. MARTINEZ; S. MERINO

    2011-01-01

    The effect that climatic changes can exert on parasitic interactions represents a multifactor problem whose results are difficult to predict. The actual impact of changes will depend on their magnitude and the physiological tolerance of affected organisms. When the change is considered extreme (I.e. Unusual weather events that are at the extremes of the historical distribution for a given area), the probability of an alteration in an organisms' homeostasis increases dramatically. However, factors determining the altered dynamics of host-parasite interactions due to an extreme change are the same as those acting in response to changes of lower magnitude. Only a deep knowledge of these factors will help to produce more accurate predictive models for the effects of extreme changes on parasitic interactions. Extreme environmental conditions may affect pathogens directly when they include free-living stages in their life-cycles and indirectly through reduced resource availability for hosts and thus reduced ability to produce efficient anti-parasite defenses, or by effects on host density affecting transmission dynamics of diseases or the frequency of intraspecific contact. What are the consequences for host-parasite interactions? Here we summarize the present knowledge on three principal factors in determining host-parasite associations; biodiversity, population density and immunocompetence. In addition, we analyzed examples of the effects of environmental alteration of anthropogenic origin on parasitic systems because the effects are analogous to that exerted by an extreme climatic change.

  11. Tomato crop coefficient grown under mediterranean climate conditions

    DEFF Research Database (Denmark)

    Cerekovic, Natasa; Todorovic, Mladen; Snyder, Richard L.; Boari, Francesca

    The measurements of the main weather parameters for tomato crop data were collected in 2002. at experimental meteorological station "E. Pantenelli" of Bari University and CNR-Bari near Policoro (Southern Italy) to investigate the influence of weather and management on crop growth and development ...... techniques, crop management, climatic conditions changes (temperature, relative humidity, wind speed) and irrigation technique have a significant impact on the crop development and crop coefficient values.......The measurements of the main weather parameters for tomato crop data were collected in 2002. at experimental meteorological station "E. Pantenelli" of Bari University and CNR-Bari near Policoro (Southern Italy) to investigate the influence of weather and management on crop growth and development...... parameters which can contribute in difference of Kc values for this climatic region. The results of investigations on Policoro data confirmed relevant difference in the length of the growing period in respect to the data presented in FAO 56. Therefore, careful consideration of all growing and management...

  12. The usability of green building rating systems in hot arid climates: A case study in Siwa, Egypt

    OpenAIRE

    Attia, Shady; Dabaieh, Marwa

    2013-01-01

    In the last ten years there has been a proliferation of regional building rating systems across the Middle East (ME). Most those emerging rating systems and labels emulate the British and American rating systems BREEAM and LEED that emerged in industrial countries context with an impact reduction paradigm. Thus they are neglecting the local historic, climatic, economic, technological, cultural and social context of the ME. This paper presents a case study of a recently constructed eco-lodge,...

  13. Forest associations and global climate change - current climatic conditions; Forest associations and global climate change - CCCM climatic scenario; Forest associations and global climate change - GISS climatic scenario; Forest associations and global climate change - dT1 climatic scenario; 1 : 1 000 000

    International Nuclear Information System (INIS)

    Bioclimatic areas of wood species represent the areas of natural spreading of wood species as determined by the threshold values of air temperature by climatic amplitudes established for the individual wood species. Establishment of climatic amplitudes of the individual wood species in Slovakia was based on the existing studies, which analysed the results of natural spreading of wood species in Slovakia in relation to the vertical climatic changes. The presented bioclimatic areas are assessed for the following conditions (table): · Tn contemporary climate; · CCCM (Canadian Climate Center Model) climatic scenario; · GISS (Goddard Institute for Space Studies) climatic scenario; · dT1 (National Climatic Programme) climatic scenario. (authors)

  14. Concentrations and Fractionation of Carbon, Iron, Sulfur, Nitrogen and Phosphorus in Mangrove Sediments Along an Intertidal Gradient (Semi-Arid Climate, New Caledonia

    Directory of Open Access Journals (Sweden)

    Jonathan Deborde

    2015-02-01

    Full Text Available In mangrove ecosystems, strong reciprocal interactions exist between plant and substrate. Under semi-arid climate, Rhizophora spp. are usually predominant, colonizing the seashore, and Avicennia marina develops at the edge of salt-flats, which is the highest zone in the intertidal range. Along this zonation, distribution and speciation of C, Fe, S, N, and P in sediments and pore-waters were investigated. From the land-side to the sea-side of the mangrove, sediments were characterized by I/ increase in: (i water content; (ii TOC; (iii mangrove-derived OM; II/ and decrease in: (i salinity; (ii redox; (iii pH; (iv solid Fe and solid P. Beneath Avicennia and Rhizophora, TS accumulated at depth, probably as a result of reduction of iron oxides and sulfate. The loss of total Fe observed towards the sea-side may be related to sulfur oxidation and to more intense tidal flushing of dissolved components. Except the organic forms, dissolved N and P concentrations were very low beneath Avicennia and Rhizophora stands, probably as a result of their uptake by the root systems. However, in the unvegetated salt-flat, NH4+ can accumulate in organic rich and anoxic layers. This study shows: (i the evolution of mangrove sediment biogeochemistry along the intertidal zone as a result of the different duration of tidal inundation and organic enrichment; and (ii the strong links between the distribution and speciation of the different elements.

  15. Influence of climate variability on water partitioning and effective energy and mass transfer (EEMT) in a semi-arid critical zone

    Science.gov (United States)

    Zapata-Rios, X.; Brooks, P. D.; Troch, P. A.; McIntosh, J.; Rasmussen, C.

    2015-08-01

    The Critical Zone (CZ) is the heterogeneous, near-surface layer of the planet that regulates life-sustaining resources. Previous research has demonstrated that a quantification of the influxes of effective energy and mass (EEMT) to the CZ can predict its structure and function. In this study, we quantify how climate variability in the last three decades (1984-2012) has affected water availability and the temporal trends in EEMT. This study takes place in the 1200 km2 upper Jemez River Basin in northern New Mexico. The analysis of climate, water availability, and EEMT was based on records from two high elevation SNOTEL stations, PRISM data, catchment scale discharge, and satellite derived net primary productivity (MODIS). Records from the two SNOTEL stations showed clear increasing trends in winter and annual temperatures (+1.0-1.3 °C decade-1; +1.2-1.4 °C decade-1, respectively), decreasing trends in winter and annual precipitation (-41.6-51.4 mm decade-1; -69.8-73.2 mm decade-1, respectively) and maximum Snow Water Equivalent (SWE; -33.1-34.7 mm decade-1). The water partitioning fluxes at the basin scale showed statistically significant decreasing trends in precipitation (-61.7 mm decade-1), discharge (-17.6 mm decade-1) and vaporization (-45.7 mm decade-1). Similarly Q50, an indicator of snowmelt timing, is occurring 4.3 days decade-1 earlier. Results from this study indicated a decreasing trend in water availability, a reduction in forest productivity (4 g C m-2 per 10 mm of reduction in Precipitation) and EEMT (1.2-1.3 MJ m2 decade-1). These changes in EEMT point towards a hotter, drier and less productive ecosystem which may alter critical zone processes in high elevation semi-arid systems.

  16. Modeling net primary productivity of terrestrial ecosystems in the semi-arid climate of the Mongolian Plateau using LSWI-based CASA ecosystem model

    Science.gov (United States)

    Bao, Gang; Bao, Yuhai; Qin, Zhihao; Xin, Xiaoping; Bao, Yulong; Bayarsaikan, Sainbuyin; Zhou, Yi; Chuntai, Bilegtmandakh

    2016-04-01

    Since the estimate of moisture stress coefficients (MSC) in the current Carnegie-Ames-Stanford-Approach (CASA) model still requires considerable inputs from ground meteorological data and many soil parameters, here we present a modified CASA model by introducing the land-surface water index (LSWI) and scaled precipitation to model the vegetation net primary productivity (NPP) in the arid and semiarid climate of the Mongolian Plateau. The field-observed NPP data and a previously proposed model (the Yu-CASA model) were used to evaluate the performance of our LSWI-based CASA model. The results show that the NPP predicted by both the LSWI-based CASA model and the Yu-CASA model showed good agreement with the observed NPP in the grassland ecosystems in the study area, with coefficients of determination of 0.717 and 0.714, respectively. The LSWI-based CASA model also performed comparably with the Yu-CASA model at both biome and per-pixel scales when keeping other inputs unchanged, with a difference of approximately 16 g C in the growing-season total NPP and an average value of 2.3 g C bias for each month. This indicates that, unlike an earlier method that estimated MSC based entirely on climatic variables or a soil moisture model, the method proposed here simplifies the model structure, reduces the need for ground measurements, and can provide results comparable with those from earlier models. The LSWI-based CASA model is potentially an alternative method for modelling NPP for a wide range of vegetation types in the Mongolian Plateau.

  17. Isotope study of impact of climatic changes on hydrological cycle in Central Asian and Caspian arid region

    International Nuclear Information System (INIS)

    The problem of replenishment of groundwater and lakes in the Central Asian and Caspian and region during the Late Pleistocene-Holocene transition time on the basis of isotope studies is discussed. Interpretation of the oxygen and carbon isotope record from the palaeogroundwaters and lake sediments shows that during climate cooling over the Eurasian continent its humid zone was extended towards the and regions. In addition, voluminous glaciers were accumulated in the northern and southern mountain regions. Intensive melting of the glaciers during the transition time provided effective replenishment of the aquifers and lakes in the and zone by fresh water. (author)

  18. Capturing 3D resistivity of semi-arid karstic subsurface in varying moisture conditions using a wireless sensor network

    Science.gov (United States)

    Barnhart, K.; Oden, C. P.

    2012-12-01

    The dissolution of soluble bedrock results in surface and subterranean karst channels, which comprise 7-10% of the dry earth's surface. Karst serves as a preferential conduit to focus surface and subsurface water but it is difficult to exploit as a water resource or protect from pollution because of irregular structure and nonlinear hydrodynamic behavior. Geophysical characterization of karst commonly employs resistivity and seismic methods, but difficulties arise due to low resistivity contrast in arid environments and insufficient resolution of complex heterogeneous structures. To help reduce these difficulties, we employ a state-of-the-art wireless geophysical sensor array, which combines low-power radio telemetry and solar energy harvesting to enable long-term in-situ monitoring. The wireless aspect removes topological constraints common with standard wired resistivity equipment, which facilitates better coverage and/or sensor density to help improve aspect ratio and resolution. Continuous in-situ deployment allows data to be recorded according to nature's time scale; measurements are made during infrequent precipitation events which can increase resistivity contrast. The array is coordinated by a smart wireless bridge that continuously monitors local soil moisture content to detect when precipitation occurs, schedules resistivity surveys, and periodically relays data to the cloud via 3G cellular service. Traditional 2/3D gravity and seismic reflection surveys have also been conducted to clarify and corroborate results.

  19. Influence of climate variability on water partitioning and effective energy and mass transfer in a semi-arid critical zone

    Science.gov (United States)

    Zapata-Rios, Xavier; Brooks, Paul D.; Troch, Peter A.; McIntosh, Jennifer; Rasmussen, Craig

    2016-03-01

    The critical zone (CZ) is the heterogeneous, near-surface layer of the planet that regulates life-sustaining resources. Previous research has demonstrated that a quantification of the influxes of effective energy and mass transfer (EEMT) to the CZ can predict its structure and function. In this study, we quantify how climate variability in the last 3 decades (1984-2012) has affected water availability and the temporal trends in EEMT. This study takes place in the 1200 km2 upper Jemez River basin in northern New Mexico. The analysis of climate, water availability, and EEMT was based on records from two high-elevation SNOTEL stations, PRISM data, catchment-scale discharge, and satellite-derived net primary productivity (MODIS). Results from this study indicated a decreasing trend in water availability, a reduction in forest productivity (4 g C m-2 per 10 mm of reduction in precipitation), and decreasing EEMT (1.2-1.3 MJ m2 decade-1). Although we do not know the timescales of CZ change, these results suggest an upward migration of CZ/ecosystem structure on the order of 100 m decade-1, and that decadal-scale differences in EEMT are similar to the differences between convergent/hydrologically subsidized and planar/divergent landscapes, which have been shown to be very different in vegetation and CZ structure.

  20. Implications of climate change on crop water requirements in arid region: An example of Al-Jouf, Saudi Arabia

    Directory of Open Access Journals (Sweden)

    Shakhawat Chowdhury

    2016-01-01

    Full Text Available This study investigated possible implications of climate change on crop water requirements (CWRs from 2011 to 2050 in Al-Jouf, Saudi Arabia. CWR were predicted for four scenarios: (i current temperature and rainfall (S1; (ii temperature in 2050 and current state of rainfall (S2; (iii rainfall in 2050 and current state of temperature (S3 and (iv temperature and rainfall in 2050 (S4. Assuming no change in the regulations relating to agriculture and irrigation in future, CWR were predicted to be 873 and 931 million cubic meters (MCM per year for the S1 and S4 scenarios, respectively, indicating an increase of 58 MCM from 2011 to 2050. On an average, 1 °C increase in temperature may increase the overall CWR by 2.9% in this region. Following linear pattern of increase, slope of CWR was determined as 1.5 MCM/year from 2011, which is equivalent to the CWR of producing approximately 600 tons of wheat/year. The increase of CWR was due to the increase in temperature mainly, while the effect of rainfall changes was minimal. Sensitivity analysis on crop growing seasons showed that the shift of wheat growing season might conserve significant amount of groundwater. This study might be useful in explaining the negative effects of climate change on CWR in Al-Jouf and better planning for water resources management.

  1. How rural land use management facilitates drought risk adaptation in a changing climate - A case study in arid northern China.

    Science.gov (United States)

    Lei, Yongdeng; Zhang, Hailin; Chen, Fu; Zhang, Linbo

    2016-04-15

    Under a warming climate, frequent drought and water scarcity in northern China have severely disrupted agricultural production and posed a substantial threat to farmers' livelihoods. Based on first-hand data collected through in-depth interviews with local managers and farmer households, this study evaluated the effectiveness of rural land use management in mitigating drought risk, ensuring food security and improving farmers' livelihoods. Our findings indicate that a) reforestation on low-yield cropland not only can improve the eco-environment but can also prominently mitigate the production risk to local farmers; b) replacing the traditional border irrigation with sprinkler irrigation has substantially curbed agricultural water usage and increased the per unit of output; and c) in recent years, instead of planting water-intensive grain crops, local farmers cultivated more forage crops to raise animals, which greatly diversified their income sources and reduced the drought risk of agricultural production. By performing an empirical case study in drought-prone Inner Mongolia, this study provides decision-makers with insights into how to strategically adapt to drought risk and reduce rural poverty within the broader context of climate change. PMID:26815296

  2. Agronomic Importance of First Development of Chickpea (Cicer arietinum L. Under Semi-arid Conditions: I. Effect of Powder Humic Acid

    Directory of Open Access Journals (Sweden)

    N. Bayraktar

    2012-01-01

    Full Text Available Due to slow growth and weakness of the first development of chickpea (Cicer arietinum L. plant could not combatted with weeds and easily get caught up by Ascochyta blight (Ascochyta rabiei (Pass Labr. disease; esp. under the late sowing and semi-arid conditions, due to effect of biotic and abiotic stress factors, significant yield losses could be arised. To be able to avoid from them is only possible to accelerate the first development of this crop. So, one of the best solutions is to use of “soil conditioner” chemical compounds such as HA at optimum dose. With this aim, it was established in order to find out the optimum dose range of HA. Three doses (D0 = 0 g, D1 = 100 g and D2 = 200 g, four varieties (V1 = Er–99, V2 = Gökçe, V3 = ILC-482 and V4 = Australia and five yield components (Plant Height (PH, First pod height (FPH, Number of Branches per Plant (NBP, Number of Pods per Plant (NPP and Number of seeds per pod (NSP were investigated. Obtained results are: Recommended (Optimum HA doses and interactions were ranged and found as (V4>V2=V3>V1; (D2>D0=D1; (D1xV4 for the PH and FPH, (D2xV3 for the NBP and (D1xV3 for the NPP, respectively. It was concluded that when the recommended HA dose applied, it was seen that the first development has been clearly accelerated and increased under the semi-arid conditions in terms of investigated traits and cultivars.

  3. Agronomic importance of first development of chickpea (Cicer arietinum L.) under semi-arid conditions: I. Effect of powder humic acid.

    Science.gov (United States)

    Ulukan, H; Bayraktar, N; Koçak, N

    2012-02-15

    Due to slow growth and weakness of the first development of chickpea (Cicer arietinum L.) plant could not combatted with weeds and easily get caught up by Ascochyta blight (Ascochyta rabiei (Pass) Labr.) disease; esp. under the late sowing and semi-arid conditions, due to effect of biotic and abiotic stress factors, significant yield losses could be arised. To be able to avoid from them is only possible to accelerate the first development of this crop. So, one of the best solutions is to use of "soil conditioner" chemical compounds such as HA at optimum dose. With this aim, it was established in order to find out the optimum dose range of HA. Three doses (D0 = 0 g, D1 = 100 g and D2 = 200 g), four varieties (V1 = Er-99, V2 = Gökçe, V3 = ILC-482 and V4 = Australia) and five yield components Plant Height (PH), First pod height (FPH), Number of Branches per Plant (NBP), Number of Pods per Plant (NPP) and Number of seeds per pod (NSP) were investigated. Obtained results are: Recommended (Optimum) HA doses and interactions were ranged and found as (V4 > V2 = V3 > V1); (D2 > D0 = D1); (D1 x V4) for the PH and FPH, (D2 x V3) for the NBP and (D1 x V3) for the NPP, respectively. It was concluded that when the recommended HA dose applied, it was seen that the first development has been clearly accelerated and increased under the semi-arid conditions in terms of investigated traits and cultivars. PMID:22816179

  4. Reclaimed water as a main resource to enhance the adaptive capacity to climate change in semi-arid Mediterranean agricultural areas using Earth Observation products

    Science.gov (United States)

    Pavia Rico, Ana; Lopez-Baeza, Ernesto; Matieu, Pierre-Philippe; Hernandez Sancho, Francesc; Loarte, Edwin

    Lack of water is being a big problem in semi-arid areas to make agricultural profits. Most of Mediterranean countries like Spain, Italy, Greece or Cyprus and other countries like Morocco, the Arab United Emirates, South-American countries or China are starting to reuse wastewater as adaptation to climate change water scarcity. Drought areas are nowadays increasing, thus making fertile areas unproductive. For this reason, the European trend is to work on reusing wastewater as a solution to water scarcity in agriculture. Moreover, since population is growing fast, wastewater production is increasing as well as drinkable water demand, thus making reclaimed water as the water guarantee for irrigation and better agricultural management. This work represents a preliminary initiative to check, analyse and monitor the land by using remote sensing techniques to identify and determine the potential lands that used to be productive in the past, are now abandoned, and we want to recuperate to obtain socio-economic benefits. On top of this, this initiative will clearly enhance the adaption capacity of rural/agricultural lands to climate change. Alternatively to reclaimed water, greenhouses, desalination plants or transboarding water do not really eliminate the problem but only offer a temporary solution, make spending plenty of money and always provoking irreversible damages to the environment. The pilot area to first develop this research is the Valencia and Murcia Autonomous Communities located in the Spanish Mediterranean Coastline. An added value of this work will be to develop a methodology transferable to other potential countries with similar climatic characteristics and difficulties for irrigation, by using remote sensing methods and techniques. The remote sensing products obtained provide full information about the current state of the potential lands to grow crops. Potential areas are then being selected to carry out a socio-economic analysis leading to: (i

  5. Effects of climate change on agriculture and environment in the semi-arid tropic - with Senegal as an example

    International Nuclear Information System (INIS)

    Some of the likely effects of the climate changes, projected by IPCC, on agriculture and environment in Senegal have been described. If rainfall does indeed increase, as suggested by the IPCC WG1 report, reversal of negative trends in vegetation productivity, associated with the droughts of the last decades on the 20th Century, will be expected to occur. Present tendencies towards encroachment of crop cultivation on rangelands will be reinforced. These effects are likely to be economically beneficial to Senegal, yet their importance will be determined by the extent to which other factors will counteract them. With respect to crop and rangeland productivity nutrient-limitations will become increasingly important if not avoided by increased application of mineral fertilizers which is presently uneconomical. If rainfall does not increase significantly, the probable higher temperatures will tend to decrease crop and rangeland productivity, due to an increase in evapotranspirations rates. Also, the competition for water resources is likely to be intensified, especially the water resources of the Senegal River which are shared by four countries. The greater international focus on climate issues also affects Senegal by putting an economic value on carbon storage and avoidance of emissions of greenhouse gases. Current trends of expanding agriculture into rangelands and woodland areas imply a reduction in the storage of carbon in vegetation and soils. The use of fire as a natural resource management practice may have significant impacts on emissions, and may therefore be affected by emission policies. The challenge for Senegal will be to develop policies and preparedness in order to adapt to the changes that are likely to come. Presently, government policies are only to a very limited extent taking the projected change into consideration. (LN)

  6. Long-term effect of irrigation with waste water on soil microbial community in semi-arid conditions

    Science.gov (United States)

    García-Orenes, Fuensanta; Morugan, Alicia; Mar Alguacil, Mª; Roldan, Antonio

    2013-04-01

    The water shortage is one of the most serious environmental problems in semi-arid areas around the world, which implicates the search for alternatives sources of water to satisfy the water demand in these regions. The use of wastewater for the irrigation of agricultural land is one of most suitable solutions to save better quality water when the natural resources are scarce. The reuse of wastewater in soil irrigation is not a new practise and is increasing in many places around the world; however the implications for the sustainability of agro-ecosystems must be studied in deep. The objective of this work was to study the effects of the long-term irrigation with treated wastewater in soil microbial community (evaluated as abundance of phospholipid fatty acids, PLFA). The experiment was conducted in an area located in Alicante (Southeast Spain) (Coordinates 38° 17´38" N, 0° 33´50" W). During 40 years an experimental Citrus aurantium L. (orange tree) orchard has been drip-irrigated with waste water, and control plots with the same characteristics subjected to drip irrigation with fresh water, were also stabilised during all the experimental period. Soil samples from individual trees were colleted in a randomised design with three replicates for each irrigation treatment (irrigation with waste water and irrigation with fresh water), to analyse the abundance of PLFA at the end of the experiment. The results show a major content of total PLFA in soils irrigated with fresh water, also these soils showed higher variety of PLFAs, and so a higher variety of groups of microorganims.

  7. Assessment of future agricultural conditions in southwestern Africa using fuzzy logic and high-resolution climate model scenarios

    Directory of Open Access Journals (Sweden)

    Weinzierl, Thomas

    2015-12-01

    Full Text Available Climate change is expected to have a major impact on the arid savanna regions of southwestern Africa, such as the Okavango Basin. Precipitation is a major constraint for agriculture in countries like Namibia and Botswana and assessments of future crop growth conditions are in high demand. This GIS-based approach uses reanalysis data and climate model output for two scenarios and compares them to the precipitation requirements of the five most important crops grown in the region: maize, pearl millet, sorghum, cassava and cow pea. It also takes into account the dominant soil types, as plant growth is also limited by nutrient-poor soils with unfavorable physical and chemical properties. The two factors are then combined using a fuzzy logic algorithm. The assessment visualizes the expected shifts in suitable zones and identifies areas where farming without irrigation may experience a decline in yields or may even no longer be possible at the end of the 21st century. The results show that pearl millet is the most suitable crop in all scenarios while especially the cultivation of maize, sorghum and cow pea may be affected by a possible reduction of precipitation under the high-emission scenario.

  8. Classification and ordination of main plant communities along an altitudinal gradient in the arid and temperate climates of northeastern Mexico

    Science.gov (United States)

    Castillón, Eduardo Estrada; Arévalo, José Ramón; Quintanilla, José Ángel Villarreal; Rodríguez, María Magdalena Salinas; Encina-Domínguez, Juan Antonio; Rodríguez, Humberto González; Ayala, César Martín Cantú

    2015-10-01

    Quantitative data on the ecology of the main plant communities along an altitudinal gradient in northeastern Mexico were obtained with the aim of identifying the most important environmental variables that affect plant distribution and composition. The main threats to these communities were also investigated. Importance value index (IVi) of the 39 most important species and 16 environmental variables were recorded at 35 altitudinal gradients each spaced at intervals of at least 100-m altitude. Classification and ordination of vegetation showed six well-differentiated but overlapping plant communities: alpine meadow, cold conifer forest, mesic mixed forest, xeric scrub, Tamaulipan piedmont scrub, and halophytic grassland. Altitude, minimum and average temperatures, and organic matter content are the main variables affecting the plant distribution in northeastern Mexico. Urban growth, mechanized agriculture, and changes in land use are the main threats in the short and medium term to plant communities in this area. Climate change also seems to be having an impact at present or in the near future as shown by the presence of exotic shrubs from warmer areas in mesic and temperate areas inhabited by oak and oak-pine forest.

  9. Physiological and productive responses of multiparous lactating Holstein cows exposed to short-term cooling during severe summer conditions in an arid region of Mexico

    Science.gov (United States)

    Avendaño-Reyes, L.; Hernández-Rivera, J. A.; Álvarez-Valenzuela, F. D.; Macías-Cruz, U.; Díaz-Molina, R.; Correa-Calderón, A.; Robinson, P. H.; Fadel, J. G.

    2012-11-01

    Heat stress generates a significant economic impact for the dairy industry in arid and semi-arid regions of the world, so that heat abatement is an important issue for dairy producers. The objective of this study was to evaluate effects of two short-term cooling periods on physiological and productive status of lactating Holstein cows during hot ambient temperatures. Thirty-nine multiparous cows were blocked by milk yield and assigned to one of three treatments including: control group (C), cows cooled before milking time (0500 and 1700 h daily, 1 h cooling); AM group, cows cooled at 1000 h and before milking (2 h cooling); and AM + PM group, cows cooled at 1100, 1500 and 2200 h, as well as before milking (4 h cooling). The cooling system was placed in the holding pen which the cows were moved through for cooling. Respiratory rate, and temperatures of thurl and right flank, were lower ( P < 0.05) in cows from the AM + PM group than AM and C cows during the morning and afternoon. However, udder temperature was higher in the AM + PM group compared to AM and C groups during the afternoon, although lower than the AM group during the morning. Rectal temperature was similar in all groups. Thyroxin concentrations tended ( P < 0.10) to be lower in AM + PM relative to the AM and C groups. The AM + PM group had higher ( P < 0.05) milk production than C (18.70 vs. 17.43 kg, respectively), and AM + PM cows had a trend ( P < 0.10) to increased milk energy output vs. the C and AM groups (13.75 vs. 13.18 and 13.15 Mcal, respectively). Protein and fat in milk, body condition score, glucose, cholesterol, triglycerides and triiodothyronine were similar among the groups. Four hours of cooling with spray and fans during severe summer temperatures only modestly improved milk yield of lactating Holstein cows.

  10. Icing conditions over Northern Eurasia in changing climate

    International Nuclear Information System (INIS)

    Icing conditions, particularly in combination with wind, affect greatly the operation of overhead communication and transmission lines causing serious failures, which result in tremendous economic damage. Icing formation is dangerous to agriculture, forestry, high seas fishery, for land and off coast man-made infrastructure. Quantitative icing characteristics such as weight, thickness, and duration are very important for the economy and human wellbeing when their maximum values exceed certain thresholds. Russian meteorological stations perform both visual and instrumental monitoring of icing deposits. Visual monitoring is ocular estimation of the type and intensity of icing and the date of ice appearance and disappearance. Instrumental monitoring is performed by ice accretion indicator that in addition to the type, intensity and duration of ice deposits reports also their weight and size. We used observations at 958 Russian stations for the period 1977–2013 to analyze changes in the ice formation frequency at individual meteorological stations and on the territory of quasi-homogeneous climatic regions in Russia. It was found that hoar frosts are observed in most parts of Russia, but icing only occurs in European Russia and the Far East. On the Arctic coast of Russia, this phenomenon can even be observed in summer months. Statistically significant decreasing trends in occurrence of icing and hoar frost events are found over most of Russia. An increasing trend in icing weights (IWs) was found in the Atlantic Arctic region in autumn. Statistically significant large negative trends in IWs were found in the Pacific Arctic in winter and spring. (letter)

  11. Non-isothermal water flow in the vadose zone of arid and semi-arid environments

    Science.gov (United States)

    Mallants, Dirk; Gerke, Kirill; Cook, Peter

    2013-04-01

    In desert environments thermally-driven vapour flow can be an important component of the total water flux in soils. As such, vapour flow can have considerable impact on recharge estimation, with small errors in soil water flow rates resulting in relatively larger errors in the recharge estimates since recharge is a very small fraction of rainfall. The additional effects of vegetation and temperature contributions may also impact soil water movement and thus calculated recharge rates in arid and semi-arid vadose zones. Currently most methods for estimating large-scale recharge rates do not consider these various processes, which adds an unknown degree of uncertainty to recharge estimation. The HYDRUS-1D numerical simulator was used to simulate coupled isothermal liquid, isothermal vapour, non-isothermal liquid and vapour flow, and heat flow in deep variably saturated vadose zones. The considered climatic conditions are characteristic of central Australia with approximate mean annual precipitation and potential evapotranspiration rates of 300 and 3000 mm, respectively. A time series of 130 years of daily climate data provides the upper boundary conditions. Groundwater recharge under highly erratic rainfall conditions is hypothesized to be primarily episodic and linked to flood events which may be significant only once every few years. The combined effect of vegetation and temperature on water flow and soil water redistribution is discussed for both vegetated and bare soils.

  12. Groundwater flow modelling of periods with temperate climate conditions - Laxemar

    International Nuclear Information System (INIS)

    As a part of the license application for a final repository for spent nuclear fuel at Forsmark, the Swedish Nuclear Fuel and Waste Management Company (SKB) has undertaken a series of groundwater flow modelling studies. These represent time periods with different hydraulic conditions and the simulations carried out contribute to the overall evaluation of the repository design and long-term radiological safety. This report concerns the modelling of a repository at the Laxemar-Simpevarp site during temperate climate conditions as a comparison to corresponding modelling carried out for Forsmark /Joyce et al. 2010/. The collation and implementation of onsite hydrogeological and hydrogeochemical data from previous reports are used in the construction of a Hydrogeological base case (reference case conceptualisation) and then an examination of various areas of uncertainty within the current understanding by a series of model variants. The Hydrogeological base case models at three different scales, 'repository', 'site' and 'regional' make use of a discrete fracture network (DFN) and equivalent continuous porous medium (ECPM) models. The use of hydrogeological models allow for the investigation of the groundwater flow from a deep disposal facility to the biosphere and for the calculation of performance measures that will provide an input to the site performance assessment. The focus of the study described in this report has been to perform numerical simulations of the hydrogeological system from post-closure and throughout the temperate period up until the receding shoreline leaves the modelling domain at around 15,000 AD. Besides providing quantitative results for the immediate temperate period following post-closure, these results are also intended to give a qualitative indication of the evolution of the groundwater system during future temperate periods within an ongoing cycle of glacial/inter-glacial events

  13. Groundwater flow modelling of periods with temperate climate conditions - Laxemar

    Energy Technology Data Exchange (ETDEWEB)

    Joyce, Steven; Simpson, Trevor; Hartley, Lee; Applegate, David; Hoek, Jaap; Jackson, Peter; Roberts, David; Swan, David (Serco Technical Consulting Services (United Kingdom)); Gylling, Bjoern; Marsic, Niko (Kemakta Konsult AB, Stockholm (Sweden)); Rhen, Ingvar (SWECO Environment AB, Falun (Sweden))

    2010-12-15

    As a part of the license application for a final repository for spent nuclear fuel at Forsmark, the Swedish Nuclear Fuel and Waste Management Company (SKB) has undertaken a series of groundwater flow modelling studies. These represent time periods with different hydraulic conditions and the simulations carried out contribute to the overall evaluation of the repository design and long-term radiological safety. This report concerns the modelling of a repository at the Laxemar-Simpevarp site during temperate climate conditions as a comparison to corresponding modelling carried out for Forsmark /Joyce et al. 2010/. The collation and implementation of onsite hydrogeological and hydrogeochemical data from previous reports are used in the construction of a Hydrogeological base case (reference case conceptualisation) and then an examination of various areas of uncertainty within the current understanding by a series of model variants. The Hydrogeological base case models at three different scales, 'repository', 'site' and 'regional' make use of a discrete fracture network (DFN) and equivalent continuous porous medium (ECPM) models. The use of hydrogeological models allow for the investigation of the groundwater flow from a deep disposal facility to the biosphere and for the calculation of performance measures that will provide an input to the site performance assessment. The focus of the study described in this report has been to perform numerical simulations of the hydrogeological system from post-closure and throughout the temperate period up until the receding shoreline leaves the modelling domain at around 15,000 AD. Besides providing quantitative results for the immediate temperate period following post-closure, these results are also intended to give a qualitative indication of the evolution of the groundwater system during future temperate periods within an ongoing cycle of glacial/inter-glacial events

  14. Groundwater flow modelling of periods with temperate climate conditions - Forsmark

    Energy Technology Data Exchange (ETDEWEB)

    Joyce, Steven; Simpson, Trevor; Hartley, Lee; Applegate, David; Hoek, Jaap; Jackson, Peter; Swan, David (Serco Technical Consulting Services (United Kingdom)); Marsic, Niko (Kemakta Konsult AB (Sweden)); Follin, Sven (SF GeoLogic AB (Sweden))

    2010-11-15

    As a part of the license application for a final repository for spent nuclear fuel at Forsmark, the Swedish Nuclear Fuel and Waste Management Company (SKB) has undertaken a series of groundwater flow modelling studies. These represent time periods with different climate conditions and the simulations carried out contribute to the overall evaluation of the repository design and long-term radiological safety. This report concerns the modelling of a repository at the Forsmark site during temperate conditions; i.e. from post-closure and throughout the temperate period up until the receding shoreline leaves the modelling domain at around 12,000 AD. The collation and implementation of onsite hydrogeological and hydrogeochemical data from previous reports are used in the construction of a hydrogeological base case (reference case conceptualisation) and then in an examination of various areas of uncertainty within the current understanding by a series of model variants. The hydrogeological base case models at three different scales, 'repository', 'site' and 'regional', make use of continuous porous medium (CPM), equivalent continuous porous medium (ECPM) and discrete fracture network (DFN) models. The use of hydrogeological models allow for the investigation of the groundwater flow from a deep disposal facility to the biosphere and for the calculation of performance measures that will provide an input to the site performance assessment. The focus of the study described in this report has been to perform numerical simulations of the hydrogeological system from post-closure and throughout the temperate period. Besides providing quantitative results for the immediate temperate period following post-closure, these results are also intended to give a qualitative indication of the evolution of the groundwater system during future temperate periods within an ongoing cycle of glacial/inter-glacial events

  15. Groundwater flow modelling of periods with temperate climate conditions - Forsmark

    International Nuclear Information System (INIS)

    As a part of the license application for a final repository for spent nuclear fuel at Forsmark, the Swedish Nuclear Fuel and Waste Management Company (SKB) has undertaken a series of groundwater flow modelling studies. These represent time periods with different climate conditions and the simulations carried out contribute to the overall evaluation of the repository design and long-term radiological safety. This report concerns the modelling of a repository at the Forsmark site during temperate conditions; i.e. from post-closure and throughout the temperate period up until the receding shoreline leaves the modelling domain at around 12,000 AD. The collation and implementation of onsite hydrogeological and hydrogeochemical data from previous reports are used in the construction of a hydrogeological base case (reference case conceptualisation) and then in an examination of various areas of uncertainty within the current understanding by a series of model variants. The hydrogeological base case models at three different scales, 'repository', 'site' and 'regional', make use of continuous porous medium (CPM), equivalent continuous porous medium (ECPM) and discrete fracture network (DFN) models. The use of hydrogeological models allow for the investigation of the groundwater flow from a deep disposal facility to the biosphere and for the calculation of performance measures that will provide an input to the site performance assessment. The focus of the study described in this report has been to perform numerical simulations of the hydrogeological system from post-closure and throughout the temperate period. Besides providing quantitative results for the immediate temperate period following post-closure, these results are also intended to give a qualitative indication of the evolution of the groundwater system during future temperate periods within an ongoing cycle of glacial/inter-glacial events

  16. Modelling thermal comfort of visitors at urban squares in hot and arid climate using NN-ARX soft computing method

    Science.gov (United States)

    Kariminia, Shahab; Motamedi, Shervin; Shamshirband, Shahaboddin; Piri, Jamshid; Mohammadi, Kasra; Hashim, Roslan; Roy, Chandrabhushan; Petković, Dalibor; Bonakdari, Hossein

    2016-05-01

    Visitors utilize the urban space based on their thermal perception and thermal environment. The thermal adaptation engages the user's behavioural, physiological and psychological aspects. These aspects play critical roles in user's ability to assess the thermal environments. Previous studies have rarely addressed the effects of identified factors such as gender, age and locality on outdoor thermal comfort, particularly in hot, dry climate. This study investigated the thermal comfort of visitors at two city squares in Iran based on their demographics as well as the role of thermal environment. Assessing the thermal comfort required taking physical measurement and questionnaire survey. In this study, a non-linear model known as the neural network autoregressive with exogenous input (NN-ARX) was employed. Five indices of physiological equivalent temperature (PET), predicted mean vote (PMV), standard effective temperature (SET), thermal sensation votes (TSVs) and mean radiant temperature ( T mrt) were trained and tested using the NN-ARX. Then, the results were compared to the artificial neural network (ANN) and the adaptive neuro-fuzzy inference system (ANFIS). The findings showed the superiority of the NN-ARX over the ANN and the ANFIS. For the NN-ARX model, the statistical indicators of the root mean square error (RMSE) and the mean absolute error (MAE) were 0.53 and 0.36 for the PET, 1.28 and 0.71 for the PMV, 2.59 and 1.99 for the SET, 0.29 and 0.08 for the TSV and finally 0.19 and 0.04 for the T mrt.

  17. Climate Change and Crop Exposure to Adverse Weather: Changes to Frost Risk and Grapevine Flowering Conditions.

    Directory of Open Access Journals (Sweden)

    Jonathan R Mosedale

    Full Text Available The cultivation of grapevines in the UK and many other cool climate regions is expected to benefit from the higher growing season temperatures predicted under future climate scenarios. Yet the effects of climate change on the risk of adverse weather conditions or events at key stages of crop development are not always captured by aggregated measures of seasonal or yearly climates, or by downscaling techniques that assume climate variability will remain unchanged under future scenarios. Using fine resolution projections of future climate scenarios for south-west England and grapevine phenology models we explore how risks to cool-climate vineyard harvests vary under future climate conditions. Results indicate that the risk of adverse conditions during flowering declines under all future climate scenarios. In contrast, the risk of late spring frosts increases under many future climate projections due to advancement in the timing of budbreak. Estimates of frost risk, however, were highly sensitive to the choice of phenology model, and future frost exposure declined when budbreak was calculated using models that included a winter chill requirement for dormancy break. The lack of robust phenological models is a major source of uncertainty concerning the impacts of future climate change on the development of cool-climate viticulture in historically marginal climatic regions.

  18. Uncertainties in extreme precipitation under climate change conditions

    DEFF Research Database (Denmark)

    Sunyer Pinya, Maria Antonia

    The latest report from the Intergovernmental Panel on Climate Change (IPCC) states that it is unequivocal that climate change is occurring. One of the largest impacts of climate change is anticipated to be an increase in the severity of extreme events, such as extreme precipitation. Floods caused...... by extreme precipitation pose a threat to human life and cause high economic losses for society. Thus, strategies to adapt to changes in extreme precipitation are currently being developed and established worldwide. Information on the expected changes in extreme precipitation is required for the...... development of adaptation strategies, but these changes are subject to uncertainties. The focus of this PhD thesis is the quantification of uncertainties in changes in extreme precipitation. It addresses two of the main sources of uncertainty in climate change impact studies: regional climate models (RCMs...

  19. Inferring alteration conditions on Mars: Insights from near-infrared spectra of terrestrial basalts altered in cold and hot arid environments

    Science.gov (United States)

    Gurgurewicz, Joanna; Mège, Daniel; Carrère, Véronique; Gaudin, Anne; Kostylew, Joanna; Morizet, Yann; Purcell, Peter G.; Le Deit, Laetitia

    2015-12-01

    Can information on the Martian environmental conditions prevailing during the alteration of its basaltic crust be inferred from near-infrared (NIR) spectra? In order to determine whether basalts altered under arid conditions but different temperatures have different spectral signatures, NIR spectra of basalts altered in cold (Udokan volcanic field, Siberia) and hot (Ogaden Basin, Ethiopia) environments were obtained. The NIR spectra of the alteration rind surface and the internal part of the studied samples are similar, suggesting that the NIR spectra of Martian bulk rocks may be of limited help in identifying paleoenvironment conditions. Bulk rock spectra analysis reveals, however, that spectra of the least altered rocks display clear absorption bands of smectites, suggesting that a distinction between clay minerals in weakly weathered basalts and clay-rich formations cannot be based solely on analysis of infrared spectra obtained from orbit. Additional compositional information can be retrieved from rock powder spectra - zeolites present in the Udokan basalt spectra might be used to infer composition and temperature of the fluids from which they precipitated. The presence of calcite and iddingsite is ascertained by other methods, but they are not apparent in bulk rock spectra and only weakly apparent in powder spectra. The basalt samples studied display alteration products that reflect their different alteration histories; nevertheless no criterion has been found that would help in identifying the origin of the weathering water - subsurface, rainfall, or snowfall.

  20. Impact of climate and analysis of desertification processes in semi arid land in Algeria: using data of Alsat-1 and Landsat

    OpenAIRE

    Ahmed, Z; Habib, M; Sid Ali, H.; Sofiane, K.

    2015-01-01

    The degradation of natural resources in arid and semi-arid areas was highlighted dramatically during this century due to population growth and transformation of land use systems. The Algerian steppe has undergone a regression over the past decade due to drought cycle, the extension of areas cultivated in marginal lands, population growth and overgrazing. These phenomena have led to different degradation processes, such as the destruction of vegetation, soil erosion, and deterioration...

  1. Establishment of a planted field with Mediterranean shrubs in Sardinia and its evaluation for climate mitigation and to combat desertification in semi-arid regions

    OpenAIRE

    De Dato GD; Loperfido L; De Angelis P; Valentini R

    2009-01-01

    Forested areas are important in arid and semi-arid regions primarily to combat desertification, but also to increase carbon sinks. To reverse the land degradation processes, restoration in the Mediterranean Basin had been frequently obtained by planting indigenous and exotic conifers, but it has been demonstrated that shrubs are nurse species for tree seedlings. Furthermore, planting indigenous shrubs is more efficient than allochthonous in restoring degraded soils. The aims of this work were...

  2. The impact of climatic variability over the period 1961- 1990 on the soil water balance of upland soils in the North East Arid Zone of Nigeria

    OpenAIRE

    Hess, Tim M.

    1991-01-01

    Over the period 1961 – 90 the North East Arid Zone of Nigeria experienced a decline in annual rainfall totals and increased aridity which placed increasing pressure on rain fed, millet-based farming systems. The changes in seasonal rainfall total and distribution have been examined and it has been shown that the rate of decline has been consistent across the region. The decline has been dominated by reduction in the number of rain days during the middle of the rainy season and ...

  3. The influence of hot arid climate on the use of outdoor urban spaces and thermal comfort: do cultural and social backgrounds matter?

    OpenAIRE

    Aljawabra, Faisal; Nikolopoulou, Marialena

    2010-01-01

    Climate-sensitive open spaces within cities may benefit the three dimensions of sustainability affecting economic, social and environmental factors. Aiming to improve microclimatic conditions in urban spaces can enable people to spend more time outdoors, with the potential to influence the social cohesion of a space and increase economic activity. The wider aim of this research was to develop a better understanding of the complex relation between microclimate and human behaviour in open publi...

  4. Modeling hydrological regimes of lakes under climate change conditions using heat-water balance method by Budyko

    Science.gov (United States)

    Lemeshko, Natalia; Eitzinger, Josef; Kubu, Gerhard

    2013-04-01

    Global climate change will lead to increasing air temperatures over the next decades and is expected at least to be 1-2°C above the pre-industrial values in near future. Close relationships between the physical processes in the atmosphere and the surface of the planet cause not only temperature changes, but also changes in other parameters of the climate system including hydrosphere. In this context the investigations of a possible change in moisture regime with global warming are very important for assessment of the future changes in the hydrological cycle. A steady-state hydrological model has been developed for evaluation of the changes in climate and hydrological parameters with the progress of global warming. This model is based on the heat-water balance method by M. Budyko and paleoclimatic scenarios. The Budyko's heat-water balance method is based on the combined solution of energy and water balance equations, as well as two empirical dependences: the evaporation rate on soil water content and the surface runoff on precipitation and soil moisture. This method is a universal one as it was developed using empirical data of different climates, including specific humid and arid ones. The method allows to calculate the mean monthly values of evaporation, runoff and water content of the active soil layer (1 m) using data on mean monthly values of surface air temperature, air humidity, precipitation, cloudiness, surface albedo and solar radiation, both for the actual climatic conditions, and for climatic conditions different from the present ones. Some additional assumptions have been made to adapt the method for scenarios of climate change. The paleoclimate scenarios are considered to a certain extent as analogs of future climates. The scenarios used consist of regional deviation from actual climate of annual precipitation, winter and summer air temperatures for Holocene optimum (6-5 KA B.P.) and Last Interglacial (about 125 KA B.P.), which correspond to global

  5. Performance Evaluation of Modern Building Thermal Envelope Designs in the Semi-Arid Continental Climate of Tehran

    Directory of Open Access Journals (Sweden)

    Shaghayegh Mohammad

    2013-10-01

    Full Text Available In this paper we evaluate the thermal performance of a range of modern wall constructions used in the residential buildings of Tehran in order to find the most appropriate alternative to the traditional un-fired clay and brick materials, which are increasingly being replaced in favor of more slender wall constructions employing hollow clay, autoclaved aerated concrete or light expanded clay aggregate blocks. The importance of improving the building envelope through estimating the potential for energy saving due to the application of the most energy-efficient wall type is presented and the wall constructions currently erected in Tehran are introduced along with their dynamic and steady-state thermal properties. The application of a dynamic simulation tool is explained and the output of the thermal simulation model is compared with the dynamic thermal properties of the wall constructions to assess their performance in summer and in winter. Finally, the best and worst wall type in terms of their cyclic thermal performance and their ability to moderate outdoor conditions is identified through comparison of the predicted indoor temperature and a target comfort temperature.

  6. The Relationship between Joint Pain and Climate Conditions in Japan

    OpenAIRE

    Tokumori, Kimihiko; Wang, Da-Hong; Takigawa,Tomoko; Takaki, Jiro; Ogino, Keiki

    2011-01-01

    This study aimed to determine whether there was any association between the regional climate and the proportion of people with joint pain. Regional climate data between 1971 and 2000 were obtained from the Japan Meteorological Agency. The variables used in the cluster analysis included sunlight hours, amount of precipitation, number of days with precipitation, and temperature. The regional proportion of people with joint pain was obtained from the National Survey for Health in 2001. After per...

  7. Food Security Under Shifting Economic, Demographic, and Climatic Conditions (Invited)

    Science.gov (United States)

    Naylor, R. L.

    2013-12-01

    Global demand for food, feed, and fuel will continue to rise in a more populous and affluent world. Meeting this demand in the future will become increasingly challenging with global climate change; when production shocks stemming from climate variability are added to the new mean climate state, food markets could become more volatile. This talk will focus on the interacting market effects of demand and supply for major food commodities, with an eye on climate-related supply trends and shocks. Lessons from historical patterns of climate variability (e.g., ENSO and its global teleconnections) will be used to infer potential food security outcomes in the event of abrupt changes in the mean climate state. Domestic food and trade policy responses to crop output and price volatility in key producing and consuming nations, such as export bans and import tariffs, will be discussed as a potentially major destabilizing force, underscoring the important influence of uncertainty in achieving--or failing to achieve--food security.

  8. PERCEPTIONS OF CLIMATE CHANGE

    OpenAIRE

    WAITHAKA, E.; OGENDI, KIMANI; MORARA, G.; MUTUA, MAKENZI P.

    2014-01-01

    There is evidence of climate change related events in arid and semi-arid lands. People living in Arid and Semi-arid Lands are particularly vulnerable to the change. Previous studies have revealed great wealth of adaptation mechanisms developed by communities residing in therein over the course of history for their survival. Despite this, there is little or no evidence whether these developed indigenous strategies by the vulnerable communities are based on perception of climate change. The obj...

  9. Inter-comparison of four remote sensing based surface energy balance methods to retrieve surface evapotranspiration and water stress of irrigated fields in semi-arid climate

    Directory of Open Access Journals (Sweden)

    J. Chirouze

    2013-01-01

    Full Text Available Remotely sensed surface temperature can provide a good proxy for water stress level and is therefore particularly useful to estimate spatially distributed evapotranspiration. Instantaneous stress levels or instantaneous latent heat flux are deduced from the surface energy balance equation constrained by this equilibrium temperature. Pixel average surface temperature depends on two main factors: stress and vegetation fraction cover. Methods estimating stress vary according to the way they treat each factor. Two families of methods can be defined: the contextual methods, where stress levels are scaled on a given image between hot/dry and cool/wet pixels for a particular vegetation cover, and single-pixel methods which evaluate latent heat as the residual of the surface energy balance for one pixel independently from the others. Four models, two contextual (S-SEBI and a triangle method, inspired by Moran et al., 1994 and two single-pixel (TSEB, SEBS are applied at seasonal scale over a four by four km irrigated agricultural area in semi-arid northern Mexico. Their performances, both at local and spatial standpoints, are compared relatively to energy balance data acquired at seven locations within the area, as well as a more complex soil-vegetation-atmosphere transfer model forced with true irrigation and rainfall data. Stress levels are not always well retrieved by most models, but S-SEBI as well as TSEB, although slightly biased, show good performances. Drop in model performances is observed when vegetation is senescent, mostly due to a poor partitioning both between turbulent fluxes and between the soil/plant components of the latent heat flux and the available energy. As expected, contextual methods perform well when extreme hydric and vegetation conditions are encountered in the same image (therefore, esp. in spring and early summer while they tend to exaggerate the spread in water status in more homogeneous conditions (esp. in winter.

  10. Regional feedbacks under changing climate and land-use conditions

    Directory of Open Access Journals (Sweden)

    L. Batlle Bayer

    2012-04-01

    Full Text Available Ecosystem responses to a changing climate and human-induced climate forcings (e.g. deforestation might amplify (positive feedback or dampen (negative feedback the initial climate response. Feedbacks may include the biogeochemical (e.g. carbon cycle and biogeophysical feedbacks (e.g. albedo and hydrological cycle. Here, we first review the most important feedbacks and put them into the context of a conceptual framework, including the major processes and interactions between terrestrial ecosystems and climate. We explore potential regional feedbacks in four hot spots with pronounced potential changes in land-use/management and local climate: sub-Saharan Africa (SSA, Europe, the Amazon Basin and South and Southeast Asia. For each region, the relevant human-induced climate forcings and feedbacks were identified based on published literature.

    When evapotranspiration is limited by a soil water deficit, heat waves in Europe are amplified (positive soil moisture-temperature feedback. Drought events in the Amazon lead to further rainfall reduction when water recycling processes are affected (positive soil moisture-precipitation feedback. In SSA, the adoption of irrigation in the commonly rainfed systems can modulate the negative soil moisture-temperature feedback. In contrast, future water shortage in South and Southeast Asia can turn the negative soil moisture-temperature feedback into a positive one.

    Further research including advanced modeling strategies is needed to isolate the dominant processes affecting the strength and sign of the feedbacks. In addition, the socio-economic dimension needs to be considered in the ecosystems-climate system to include the essential role of human decisions on land-use and land-cover change (LULCC. In this context, enhanced integration between Earth System (ES and Integrated Assessment (IA modeling communities is strongly recommended.

  11. Regional feedbacks under changing climate and land-use conditions

    Science.gov (United States)

    Batlle Bayer, L.; van den Hurk, B. J. J. M.; Strengers, B. J.; van Minnen, J. G.

    2012-04-01

    Ecosystem responses to a changing climate and human-induced climate forcings (e.g. deforestation) might amplify (positive feedback) or dampen (negative feedback) the initial climate response. Feedbacks may include the biogeochemical (e.g. carbon cycle) and biogeophysical feedbacks (e.g. albedo and hydrological cycle). Here, we first review the most important feedbacks and put them into the context of a conceptual framework, including the major processes and interactions between terrestrial ecosystems and climate. We explore potential regional feedbacks in four hot spots with pronounced potential changes in land-use/management and local climate: sub-Saharan Africa (SSA), Europe, the Amazon Basin and South and Southeast Asia. For each region, the relevant human-induced climate forcings and feedbacks were identified based on published literature. When evapotranspiration is limited by a soil water deficit, heat waves in Europe are amplified (positive soil moisture-temperature feedback). Drought events in the Amazon lead to further rainfall reduction when water recycling processes are affected (positive soil moisture-precipitation feedback). In SSA, the adoption of irrigation in the commonly rainfed systems can modulate the negative soil moisture-temperature feedback. In contrast, future water shortage in South and Southeast Asia can turn the negative soil moisture-temperature feedback into a positive one. Further research including advanced modeling strategies is needed to isolate the dominant processes affecting the strength and sign of the feedbacks. In addition, the socio-economic dimension needs to be considered in the ecosystems-climate system to include the essential role of human decisions on land-use and land-cover change (LULCC). In this context, enhanced integration between Earth System (ES) and Integrated Assessment (IA) modeling communities is strongly recommended.

  12. Management of nutrients and water in rainfed arid and semi-arid areas. Proceedings of a consultants meeting

    International Nuclear Information System (INIS)

    Sustainable food security is needed for the arid and semi-arid regions of the tropical, subtropical and warm-temperate climatic zones. In these regions the supply of locally grown food is unreliable because much of it is produced in conditions of highly variable rainfall. Even in favourable seasons, these regions re becoming increasingly dependent on imported food. The IAEA's involvement in field studies on soil-water use dates back several years. A five year Co-ordinated Research Project on ''The Use of Nuclear and Related Techniques in Assessment of Irrigation Schedules of Field Crops to Increase Effective Use of Water in Irrigation Projects''. That project, completed in 1995, laid a solid foundation for future research. Because of a scarcity of water in many developing countries and increasing needs for sustainable food security in the face of increasing populations and lack of funds for irrigation schemes of significant dimension, research must focus on improved management of (i) the modest quantities of fertilizers that are available to farmers, (ii) the natural resources that are available to farmers for increasing soil organic matter content, and (iii) rain water. The Joint FAO/IAEA Division of Nuclear Techniques in Food and Agriculture held a Consultants Meeting on Management of Nutrients and Water in Rainfed Arid and Semi-Arid Areas for Increasing Crop Production, 26-29 May 1997

  13. The case of arid and semi-arid zones; Le cas des zones arides et semi-arides

    Energy Technology Data Exchange (ETDEWEB)

    Agoumi, A. [Ecole Hassania, Casablanca (Morocco); Stour, L. [Hassan Univ., Mohammedia (Morocco). Faculty of Sciences

    2009-07-15

    This article addressed issues regarding the conservation and sustainable use of biomass resources in arid and semi-arid zone ecosystems. Conservation strategies for climatic zones threatened by increased pressure from intensified land use, drought, and land degradation were discussed along with sustainable land use management practices. The strategies range from strict regulations for environmental protection to various forms of conservation easements, such as carbon credits. The article also supported the initiative to reduce emissions caused by deforestation and degradation (REDD). The REDD initiative proposes that future global climate agreements should first aim to reduce the total forested area lost in the tropics and then to eventually cease global deforestation. It was concluded that sustainable forestry at a global level is needed in order to achieve mitigation targets and to avoid the risk that forests may becomes a net carbon source rather than carbon sinks. 3 figs.

  14. Climate conditions in Sweden in a 100,000-year time perspective

    International Nuclear Information System (INIS)

    This report presents results from a project devoted to describing the climatic extremes within which the climate in Fennoscandia may vary over a 100,000 year time span. Based on forcing conditions which have yielded extreme conditions during the last glacial-interglacial cycle, as well as possible future conditions following continued anthropogenic emissions, projections of climate conditions have been made with climate models. Three different periods have been studied; i) a stadial within Marine Isotope Stage 3 (MIS 3) during the last glacial cycle, representing a cold period with a relatively small ice sheet covering parts of Fennoscandia, ii) the Last Glacial Maximum (LGM), with an extensive ice sheet covering large parts of northern Europe and iii) a possible future period in a climate warmer than today. The future case is characterised by high greenhouse gas concentrations in the atmosphere and a complete loss of the Greenland ice sheet. The climate modelling involved the use of a global climate model (GCM) for producing boundary conditions that were used by a regional climate model (RCM). The regional model produced detailed information on climate variables like near-surface air temperature and precipitation over Europe. These climate variables were subsequently used to force a vegetation model that produced a vegetation cover over Europe, consistent with the simulated regional climate. In a final step, the new vegetation cover from the vegetation model was used in the regional climate model to produce the final regional climate. For the studied periods, data on relevant climate parameters have been extracted from the regional model for the Forsmark and Oskarshamn areas on the Swedish east coast and the Olkiluoto region on the west coast of Finland. Due to computational constraints, the modelling efforts include only one forcing scenario per time period. As there is a large degree of uncertainty in the choice of an appropriate forcing scenario, we perform

  15. Climate conditions in Sweden in a 100,000-year time perspective

    Energy Technology Data Exchange (ETDEWEB)

    Kjellstroem, Erik; Strandberg, Gustav (Rossby Centre, SMHI, Norrkoeping (Sweden)); Brandefelt, Jenny (Dept. of Mechanics, Royal Inst. of Technology, Stockholm (Sweden)); Naeslund, Jens-Ove (Swedish Nuclear Fuel and Waste Management Co., Stockholm (Sweden)); Smith, Ben (Dept of Physical Geography and Ecosystems Analysis, Lund Univ., Lund (Sweden)); Wohlfarth, Barbara (Dept. of Geology and Geochemistry, Stockholm Univ., Stockholm (Sweden))

    2009-04-15

    This report presents results from a project devoted to describing the climatic extremes within which the climate in Fennoscandia may vary over a 100,000 year time span. Based on forcing conditions which have yielded extreme conditions during the last glacial-interglacial cycle, as well as possible future conditions following continued anthropogenic emissions, projections of climate conditions have been made with climate models. Three different periods have been studied; i) a stadial within Marine Isotope Stage 3 (MIS 3) during the last glacial cycle, representing a cold period with a relatively small ice sheet covering parts of Fennoscandia, ii) the Last Glacial Maximum (LGM), with an extensive ice sheet covering large parts of northern Europe and iii) a possible future period in a climate warmer than today. The future case is characterised by high greenhouse gas concentrations in the atmosphere and a complete loss of the Greenland ice sheet. The climate modelling involved the use of a global climate model (GCM) for producing boundary conditions that were used by a regional climate model (RCM). The regional model produced detailed information on climate variables like near-surface air temperature and precipitation over Europe. These climate variables were subsequently used to force a vegetation model that produced a vegetation cover over Europe, consistent with the simulated regional climate. In a final step, the new vegetation cover from the vegetation model was used in the regional climate model to produce the final regional climate. For the studied periods, data on relevant climate parameters have been extracted from the regional model for the Forsmark and Oskarshamn areas on the Swedish east coast and the Olkiluoto region on the west coast of Finland. Due to computational constraints, the modelling efforts include only one forcing scenario per time period. As there is a large degree of uncertainty in the choice of an appropriate forcing scenario, we perform

  16. Improving Estimation of Evapotranspiration under Water-Limited Conditions Based on SEBS and MODIS Data in Arid Regions

    OpenAIRE

    Chunlin Huang; Yan Li; Juan Gu; Ling Lu; Xin Li

    2015-01-01

    This study proposes a method for improving the estimation of surface turbulent fluxes in surface energy balance system (SEBS) model under water stress conditions using MODIS data. The normalized difference water index (NDWI) as an indicator of water stress is integrated into SEBS. To investigate the feasibility of the new approach, the desert-oasis region in the middle reaches of the Heihe River Basin (HRB) is selected as the study area. The proposed model is calibrated with meteorological an...

  17. Land Degradation Control in Arid Ecosystem Under Climate Change Context%气候变化背景下干旱生态系统土地退化防治

    Institute of Scientific and Technical Information of China (English)

    江泽慧

    2012-01-01

    气候变化是当今全球陆地生态系统所面临的最大胁迫因素。探讨气候变化背景下干旱生态系统土地退化防治,增强减缓和适应气候变化的能力,逐步恢复土地生态系统原先所具有的综合生产潜力,是亟待解决的重要课题。文中分析了气候变化对干旱生态系统土地退化的影响,从综合生态系统管理的视角,探讨了保护与恢复森林、草地、农田生态系统以增强应对气候变化的能力以及改善民生的途径,以期为全球气候变化背景下土地退化防治和干旱生态系统可持续管理提供新的思路。%Climate change is the largest stress factor challenging global territorial ecosystem.The discussion on land degradation control in arid ecosystem under the context of climate change for increasing the capacity to mitigate and adapt to the climate change and gradually restoring the integrated production potential originally possessed by land ecosystem is a pressing issue to address.The paper analyzed the effect of climate change on land degradation in arid ecosystem,and described the protection and rehabilitation of forest,grassland and farmland ecosystems,the enhancement of the response to climate change and the improvement of people's livelihood from the viewpoint of integrated ecosystem management.This study is expected to offer a new concept for land degradation control and sustainable management of arid ecosystem in the context of global climate change.

  18. Daily number of bee louse (Braula coeca) in honey bee (Apis mellifera camica and A. m. syriaca) colonies maintained under semi-arid conditions

    Institute of Scientific and Technical Information of China (English)

    Shahera Zaitoun; Abd AI-Majeed AI-Ghzawi

    2008-01-01

    Experimental work was conducted at two apiaries located in Irbid district and in Shuna North, Jordan, during the years 2004-2006. The aims of these investigations were to estimate the seasonal changes in the infestation rates of the bee louse (Braula sp.) and to develop an easy and rapid method of estimating the infestation rate on workers with bee Braula. Two major honey bee subspecies are reared in Jordan; Apis mellifera carnica and Apis mellifera syriaca were used in this study. The results showed that the infestation rate began to increase rapidly in May, reaching the season's maximum rate of 16.2%, 15.8% and 17.4% forA. ra. carnica and 22.6%, 23.9% and 22.9% forA. m. syr/aca in December of 2004,2005 and 2006, respectively. The maximum adult numbers of bees were found in April and June, whereas the minimum for the year was in January in both honey bee subspecies colonies during the study period. The actual population of the bee louse could be estimated by counting the daily dropped lice and multiplying by a factor of 158. This factor is valid for the experimental colonies of both subspecies kept for 3 years under semi-arid Mediterranean conditions.

  19. Désertification des parcours arides au Maroc

    Directory of Open Access Journals (Sweden)

    Mahyou, H.

    2010-01-01

    Full Text Available Desertification of Arid Rangelands in Morocco. Rangeland or natural arid pastures of Morocco are ecosystems where there is a natural or seminatural vegetation composed of steppes, shrubs and grassland. They cover about 82% of the Moroccan arid lands. These areas represent livelihoods for thousands of people and protect the country from desertification. Despite the importance of the rangelands and the threat of desertification, it is surprising that up to date there is no comprehensive assessment of their condition and their evolution, hindering any plan for desertification alleviation. However, the available information on selected pilot areas shows that these rangelands are threatened by desertification. It's associated with biodiversity loss and contributes to climate change. The leading causes of land degradation are the human actions combined with climate. The establishment of a comprehensive surveillance system based on remote sensing, biophysics and socio-economic data must be envisaged to provide policymakers with an operational tool adapted to the spatio-temporal monitoring of desertification.

  20. Collaborative Research for Water Resource Management under Climate Change Conditions

    Science.gov (United States)

    Brundiers, K.; Garfin, G. M.; Gober, P.; Basile, G.; Bark, R. H.

    2010-12-01

    We present an ongoing project to co-produce science and policy called Collaborative Planning for Climate Change: An Integrated Approach to Water-Planning, Climate Downscaling, and Robust Decision-Making. The project responds to motivations related to dealing with sustainability challenges in research and practice: (a) state and municipal water managers seek research that addresses their planning needs; (b) the scientific literature and funding agencies call for more meaningful engagement between science and policy communities, in ways that address user needs, while advancing basic research; and (c) empirical research contributes to methods for the design and implementation of collaborative projects. To understand how climate change might impact water resources and management in the Southwest US, our project convenes local, state, and federal water management practitioners with climate-, hydrology-, policy-, and decision scientists. Three areas of research inform this collaboration: (a) the role of paleo-hydrology in water resources scenario construction; (b) the types of uncertainties that impact decision-making beyond climate and modeling uncertainty; and (c) basin-scale statistical and dynamical downscaling of climate models to generate hydrologic projections for regional water resources planning. The project engages all participants in the research process, from research design to workshops that build capacity for understanding data generation and sources of uncertainty to the discussion of water management decision contexts. A team of “science-practice translators” facilitates the collaboration between academic and professional communities. In this presentation we contextualize the challenges and opportunities of use-inspired science-policy research collaborations by contrasting the initial project design with the process of implementation. We draw from two sources to derive lessons learned: literature on collaborative research, and evaluations provided by

  1. Hot house global climate change and the human condition

    CERN Document Server

    Strom, Robert G

    2007-01-01

    Global warming is addressed by almost all sciences including many aspects of geosciences, atmospheric, the biological sciences, and even astronomy. It has recently become the concern of other diverse disciplines such as economics, agriculture, demographics and population statistics, medicine, engineering, and political science. This book addresses these complex interactions, integrates them, and derives meaningful conclusions and possible solutions. The text provides an easy-to-read explanation of past and present global climate change, causes and possible solutions to the problem, including t

  2. Changing Energy Requirements in the Mediterranean Under Changing Climatic Conditions

    Directory of Open Access Journals (Sweden)

    George Demosthenous

    2009-09-01

    Full Text Available This study investigates the impacts of climate change on energy requirements in the Mediterranean. Energy requirements, especially for space heating and cooling, are closely linked to several weather variables, mainly air temperature. The analysis is based on daily temperature outputs from several regional climate models run at a resolution of 25 km × 25 km in the framework of EU project ENSEMBLES using the A1B emissions scenario. The impacts of changes in temperature on energy requirements are investigated using the concept of degree days, defined as the difference of mean air temperature from a base temperature. Base temperature should be chosen to coincide with the minimum energy consumption. In this way, changes in heating and cooling requirements between the reference and the future period are calculated and areas about to undergo large changes identified. These changes are calculated between a 30-year reference period 1961–1990 and a near future period 2021–2050 taking the ensemble mean of all regional climate models. The near-term future has been chosen instead of the frequently used end-of-the-century period to assist policy makers in their planning. In general, a decrease in energy requirements is projected under future milder winters and an increase under hotter summers.

  3. The Relationship between Joint Pain and Climate Conditions in Japan

    Directory of Open Access Journals (Sweden)

    Tokumori,Kimihiko

    2011-02-01

    Full Text Available This study aimed to determine whether there was any association between the regional climate and the proportion of people with joint pain. Regional climate data between 1971 and 2000 were obtained from the Japan Meteorological Agency. The variables used in the cluster analysis included sunlight hours, amount of precipitation, number of days with precipitation, and temperature. The regional proportion of people with joint pain was obtained from the National Survey for Health in 2001. After performing a cluster analysis, one-way ANOVA and Welch's test were used to determine whether the climate characteristics of the clusters were significantly different. Within each cluster, stepwise multiple linear regression analyses were performed. We found that sunlight hours showed a direct, negative association with the proportion of people with joint pain (adjusted R2=0.532, p=0.016 in cluster 1, which was characterized as the region with the fewest total hours of sunlight, less precipitation, a modest number of rainy days, and low temperature. In the other clusters, the regional female population rate (cluster 2 and the senior population rate (cluster 3, 4 were the primary predictors. We concluded that the degree of exposure to sunlight may play a crucial role in prevention of joint pain. This finding should encourage people to set aside some time for staying outdoors in their daily lives.

  4. Performance of high-protein mutant lines of triticum aestivum (L.) under-arid conditions of Syria

    International Nuclear Information System (INIS)

    The agronomical characters of nine high-protein mutant lines of T. aestivum produced by the IAEA were studied along with their mother line Mex22A and four local cultivars. The experiments were carried out under rainfed conditions in 1990 and 1991 in southern Syria. Statistical analysis revealed significant differences among the lines in all characters. Genotype by environment interaction was significant for all characters except for N yield. There was a negative correlation between grain nitrogen concentration (GNC) and yield. However, two of the check cultivars and seven mutant lines had similar yield to Mex22A with grater Gnc. The other two mutant lines, 5074M and E296, were very late in heading and were characterized by low yield with extremely high GNC. Spikes per square meter contributed most to grain yield followed by number of seeds per spike and lastly seed weight. SDS sedimentation test values were negatively correlated with GNC. Polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulphate (SDS-PAGE) was used to assay for high molecular weight (HMW) gluten in protein subunits of the grain endosperm. The results showed the presence of HMW gluten in GluD1 subunits 2+12 in Mex22A and all IAEA genotypes. Check varieties L92-6, Buhuth 4 and Cham 2 contain the good quality allelic GluD1 subunits 5+10. Nevertheless, 4 of 9 IAEA mutant lines were characterized by having higher SDS sedimentation values due to the presence of Glu-B1 subunits 17+18 when compared to those that had subunits 7+8. (author), 20 Refs., 2 Figs., 6 Tabs

  5. Sustainability Challenges from Climate Change and Air Conditioning Use in Urban Areas

    Directory of Open Access Journals (Sweden)

    Karin Lundgren

    2013-07-01

    Full Text Available Global climate change increases heat loads in urban areas causing health and productivity risks for millions of people. Inhabitants in tropical and subtropical urban areas are at especial risk due to high population density, already high temperatures, and temperature increases due to climate change. Air conditioning is growing rapidly, especially in South and South-East Asia due to income growth and the need to protect from high heat exposures. Studies have linked increased total hourly electricity use to outdoor temperatures and humidity; modeled future predictions when facing additional heat due to climate change, related air conditioning with increased street level heat and estimated future air conditioning use in major urban areas. However, global and localized studies linking climate variables with air conditioning alone are lacking. More research and detailed data is needed looking at the effects of increasing air conditioning use, electricity consumption, climate change and interactions with the urban heat island effect. Climate change mitigation, for example using renewable energy sources, particularly photovoltaic electricity generation, to power air conditioning, and other sustainable methods to reduce heat exposure are needed to make future urban areas more climate resilient.

  6. Tourism and climate conditions in San Juan, Puerto Rico, 2000-2010

    Directory of Open Access Journals (Sweden)

    Pablo A. Méndez-Lázaro

    2014-06-01

    Full Text Available The general behavior of the tourism sector in Puerto Rico, with its marked seasonality, hints at a close relationship between tourism activities and climate conditions. Even if weather condition is only one of many variables considered by travelling tourists, climate conditions weigh heavily in the majority of the decisions. The effect of climate variability on the environment could be manifested in warmer temperature, heat waves, and changes in the frequency of extreme weather events, such as severe storms and hurricanes, floods, and sea level rise. These conditions affect different sectors of society, among them public health and the economy. Therefore, our research has two main objectives: to establish a tourism climate index (TCI for Puerto Rico and to analyze if occupancy rates in hotels correspond to local weather conditions. Even though there are many other variables that could have positive or negative effects on tourism activities, results showed a significant association between occupancy rate in Puerto Rico and climate indexes. According to both TCI and the mean historical climate for tourism indexes, the most favorable months for tourism in Puerto Rico were February and March (winter, whereas the worst season was the end of August and the beginning of September (summer-fall. Although winter represents dry conditions and lower temperatures in San Juan, it also represents the highest occupancy rate during the years examined. In summer and fall, data showed high occupancy rates, yet climate conditions were not suitable; these months also correspond to the hurricane season. During this season, high relative occupancy rates responded to internal and local tourism patterns. It can therefore be assumed that until the climate-tourism relationship is well characterized, there is little hope of fully understanding the potential economic effects, detrimental or beneficial, of global climate change, not only on tourism in Puerto Rico, but on

  7. Understanding yields in alley cropping maize (Zea mays L. ) and Cassia siamea Lam. under semi-arid conditions in Machakos,Eastern Kenya

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Six seasons of experiments in Machakos, Kenya, revealed that above about 150 mm of rainfall, maize yields per row in alley cropped “replacement” agroforestry (AF) plots, of Cassia siamea Lam. and maize (Zea mays, cv. Katumani Composite B), may be expected to exceed those in the control (sole maize) plots. Such yields were insufficient to compensate for the area “lost” to the hedgerows. Below about 150 mm the control plots may be expected to perform better. This result was due to competition for water. Greater association of the fine roots of Cassia and maize was observed in the middle of the alleys than near the hedgerows. Photosynthetic consequences of shading were insignificant relative to other factors. In the alleys, reductions of soil temperature due to shade in the western and eastern maize rows were higher than in the middle row. Soil moisture extraction was higher in the AF than in the control plots. In the AF plots, moisture extraction was greater under the central maize rows than under those nearest the Cassia. Yield patterns followed such soil temperature and soil moisture patterns. Maize transpiration and photosynthetic rates were significantly higher in the control than in the AF plots during a below-average rainy season but not during above-average rainy seasons. It is concluded that alley cropping under semi-arid conditions should be approached differently from the system worked on. It must at least provide strong physical protection of crops and/or soils and have a strong economic incentive to be of interest to the farmers.

  8. Varroa destructor and viruses association in honey bee colonies under different climatic conditions.

    Science.gov (United States)

    Giacobino, Agostina; Molineri, Ana I; Pacini, Adriana; Fondevila, Norberto; Pietronave, Hernán; Rodríguez, Graciela; Palacio, Alejandra; Bulacio Cagnolo, Natalia; Orellano, Emanuel; Salto, César E; Signorini, Marcelo L; Merke, Julieta

    2016-06-01

    Honey bee colonies are threatened by multiple factors including complex interactions between environmental and diseases such as parasitic mites and viruses. We compared the presence of honeybee-pathogenic viruses and Varroa infestation rate in four apiaries: commercial colonies that received treatment against Varroa and non-treated colonies that did not received any treatment for the last 4 years located in temperate and subtropical climate. In addition, we evaluated the effect of climate and Varroa treatment on deformed wing virus (DWV) amounts. In both climates, DWV was the most prevalent virus, being the only present virus in subtropical colonies. Moreover, colonies from subtropical climate also showed reduced DWV amounts and lower Varroa infestation rates than colonies from temperate climate. Nevertheless, non-treated colonies in both climate conditions are able to survive several years. Environment appears as a key factor interacting with local bee populations and influencing colony survival beyond Varroa and virus presence. PMID:27083139

  9. Assessment of hydraulic properties of sedimentary and volcanic aquifer systems under arid conditions in the Republic of Djibouti (Horn of Africa)

    Science.gov (United States)

    Jalludin, Mohamed; Razack, Moumtaz

    The Republic of Djibouti (23,000 km2 500,000 inhabitants), located within the Horn of Africa, undergoes an arid climate with an average annual rainfall less than 150 mm. Water resources are provided up to 98% by groundwater. Two types of aquifers are encountered: volcanic and sedimentary aquifers. This paper focuses on the assessment of their hydraulic properties, which is necessary for future tasks regarding the management of these aquifers. To this end, a data base consisting of all available pumping test data obtained since the 1960s was compiled. Pumping tests have been interpreted to determine transmissivity. Solely for volcanic aquifers, transmissivity also has been estimated through an empirical relationship using specific capacity corrected for turbulent well losses. The transmissivity of each type of aquifer can span up to four orders of magnitude, pointing out their strong heterogeneity. For the various volcanic rocks, the younger the rock, the higher the transmissivity. The transmissivity of volcanic rocks has therefore decreased in the course of geological time. At present, a much better understanding of the hydraulic properties of these complex aquifers has been obtained, which should enable optimal management of their groundwater resources through the use of numerical modeling. La République de Djibouti (23,000 km2 500,000 habitants), située dans la Corne de l'Afrique, subit un climat aride avec une pluviométrie moyenne annuelle inférieure à 150 mm. Les ressources en eau sont fournies à plus de 98% par les eaux souterraines contenues dans des aquifères sédimentaires ou volcaniques. Cet article a pour objectif l'évaluation des propriétés hydrauliques de ces aquifères, étape indispensable pour entreprendre par la suite des études en vue de la gestion de ces aquifères. Une base rassemblant les données d'essais par pompage disponibles depuis les années Soixante a d'abord été établie. Les essais par pompage ont été interprétés pour

  10. Assessment of hydraulic properties of sedimentary and volcanic aquifer systems under arid conditions in the Republic of Djibouti (Horn of Africa)

    Science.gov (United States)

    Jalludin, Mohamed; Razack, Moumtaz

    The Republic of Djibouti (23,000 km2 500,000 inhabitants), located within the Horn of Africa, undergoes an arid climate with an average annual rainfall less than 150 mm. Water resources are provided up to 98% by groundwater. Two types of aquifers are encountered: volcanic and sedimentary aquifers. This paper focuses on the assessment of their hydraulic properties, which is necessary for future tasks regarding the management of these aquifers. To this end, a data base consisting of all available pumping test data obtained since the 1960s was compiled. Pumping tests have been interpreted to determine transmissivity. Solely for volcanic aquifers, transmissivity also has been estimated through an empirical relationship using specific capacity corrected for turbulent well losses. The transmissivity of each type of aquifer can span up to four orders of magnitude, pointing out their strong heterogeneity. For the various volcanic rocks, the younger the rock, the higher the transmissivity. The transmissivity of volcanic rocks has therefore decreased in the course of geological time. At present, a much better understanding of the hydraulic properties of these complex aquifers has been obtained, which should enable optimal management of their groundwater resources through the use of numerical modeling. La République de Djibouti (23,000 km2 500,000 habitants), située dans la Corne de l'Afrique, subit un climat aride avec une pluviométrie moyenne annuelle inférieure à 150 mm. Les ressources en eau sont fournies à plus de 98% par les eaux souterraines contenues dans des aquifères sédimentaires ou volcaniques. Cet article a pour objectif l'évaluation des propriétés hydrauliques de ces aquifères, étape indispensable pour entreprendre par la suite des études en vue de la gestion de ces aquifères. Une base rassemblant les données d'essais par pompage disponibles depuis les années Soixante a d'abord été établie. Les essais par pompage ont été interprétés pour

  11. Environmental risk of climate change and groundwater abstraction on stream ecological conditions

    DEFF Research Database (Denmark)

    Seaby, Lauren Paige; Bøgh, Eva; Jensen, Niels H.

    and risk to stream ecological conditions. We find low flow and annual discharge to be most impacted by scenarios of climate change, with high variation across climate models (+/- 40% change). Doubling of current groundwater abstraction rates reduces annual discharge by approximately 20%, with higher...... flows and groundwater levels are of interest, as they relate to aquatic habitat and nitrate leaching, respectively. This study evaluates the risk to stream ecological conditions for a lowland Danish catchment under multiple scenarios of climate change and groundwater abstraction. Projections of future...... climate from 11 ENSEMBLES climate models are first bias corrected with a distribution based scaling method and then used to force hydrological simulations of stream discharge, groundwater recharge, and nitrate leaching from the root zone. Hydrological modelling utilises a sequential coupling methodology...

  12. Soil organic carbon of European forest soils: current stock and projections under climate change conditions

    Science.gov (United States)

    Caddeo, Antonio; Marras, Serena; Spano, Donatella; Sirca, Costantino

    2016-04-01

    Soil organic carbon (SOC) represents the largest terrestrial carbon pool, and it is subjected to climate change impacts. In Europe, a limited number of studies makes a wide-scale comparison of SOC stock and changes under climate change conditions, and most of them are related to agricultural soils. In this work, the SOC stock of the forested areas of Europe (obtained from the CORINE 2006 Land Use Map) was assessed at 1 km resolution using the agro-ecosystem SOC model CENTURY. The results of the model were compared with independent observational datasets (i.e. LUCAS Topsoil Survey Database). In addition, climate simulations (RCPs 4.5 and 8.5) using the CMCC (Euro-Mediterranean Centre on Climate Change) and the CORDEX dataset were used to estimate the SOC changes of these areas under climate change conditions.

  13. EFFECT OF POLYETHYLENE BLACK PLASTIC MULCH ON GROWTH AND YIELD OF TWO SUMMER VEGETABLE CROPS UNDER RAIN-FED CONDITIONS UNDER SEMI-ARID REGION CONDITIONS

    Directory of Open Access Journals (Sweden)

    Atif Y. Mahadeen

    2014-01-01

    Full Text Available Water use efficiency in agriculture can be enhanced by several strategies mainly by reducing evaporation from the soil surface. The mulching techniques were being used widely in irrigated crop production worldwide. The mulching techniques can be also implemented in summer vegetables production under rain-fed conditions. The current study aimed at evaluating the effect of polyethylene black plastic mulch on growth and yield of okra, Abelmoschus esculentus and summer squash, Cucurbita pepo L. under rain-fed conditions of Jordan. Two field experiments were conducted during summer growing season at Al-Rabbah Agricultural Research Station, Mu’tah University, Jordan. Soil cover treatments were polyethylene black plastic mulch and no mulch (bare soil. The results indicated that the mulched plots had higher soil moisture content than bare soil plots, which has positively reflected on vegetative and yield parameters. Using polyethylene plastic mulch had pronounced positive effect on yield of okra and squash as compared to bare soil. Early, middle, late and total yield of both vegetable crops were significantly increased in plots covered with plastic mulch. In addition, fruit number and weight had also an increasing trend as fruit yield. Plots covered with black plastic mulch were produced higher fresh and dry weights of both vegetable crops. It ban be concluded that using black plastic mulch as a soil cover increased okra and squash vegetative growth and yield under rain-fed conditions.

  14. Predicted performance of clay-barrier landfill covers in arid and semi-arid environments.

    Science.gov (United States)

    Sadek, S; Ghanimeh, S; El-Fadel, M

    2007-01-01

    Conventional landfill cover systems for municipal solid waste include low-permeability compacted clay barriers to minimize infiltration into the landfilled waste. Such layers are vulnerable in climates where arid to semi-arid conditions prevail, whereby the clay cover tends to desiccate and crack, resulting in drastically higher infiltration, i.e., lower cover efficiency. To date, this phenomenon, which has been reported in field observations, has not been adequately assessed. In this paper, the performance of a cover system solely relying on a clay barrier was simulated using a numerical finite element formulation to capture changes in the clay layer and the corresponding modified hydraulic characteristics. The cover system was guided by USEPA Subtitle-D minimum requirements and consisted of a clay layer underlying a protective vegetated soil. The intrinsic characteristics of the clay barrier and vegetative soil cover, including their saturated hydraulic conductivities and their soil-water characteristic curves, were varied as warranted to simulate intact or "cracked" conditions as determined through the numerical analyses within the proposed methodology. The results indicate that the levels of percolation through the compromised or cracked cover were up to two times greater than those obtained for intact covers, starting with an intact clay hydraulic conductivity of 10(-5)cm/s. PMID:16987648

  15. Analysis of extreme climatic features over South America from CLARIS-LPB ensemble of regional climate models for future conditions

    Science.gov (United States)

    Sanchez, E.; Zaninelli, P.; Carril, A.; Menendez, C.; Dominguez, M.

    2012-04-01

    An ensemble of seven regional climate models (RCM) included in the European CLARIS-LPB project (A Europe-South America Network for Climate Change Assessment and Impact Studies in La Plata Basin) are used to study how some features related to climatic extremes are projected to be changed by the end of XXIst century. These RCMs are forced by different IPCC-AR4 global climate models (IPSL, ECHAM5 and HadCM3), covering three different 30-year periods: present (1960-1990), near future (2010-2040) and distant future (2070-2100), with 50km of horizontal resolution. These regional climate models have previously been forced with ERA-Interim reanalysis, in a consistent procedure with CORDEX (A COordinated Regional climate Downscaling EXperiment) initiative for the South-America domain. The analysis shows a good agreement among them and the available observational databases to describe the main features of the mean climate of the continent. Here we focus our analysis on some topics of interest related to extreme events, such as the development of diagnostics related to dry-spells length, the structure of the frequency distribution functions over several subregions defined by more or less homogeneous climatic conditions (four sub-basins over the La Plata Basin, the southern part of the Amazon basin, Northeast Brazil, and the South Atlantic Convergence Zone (SACZ)), the structure of the annual cycle and their main features and relation with the length of the seasons, or the frequency of anomalous hot or cold events. One shortcoming that must be considered is the lack of observational databases with both time and spatial frequency to validate model outputs. At the same time, one challenging issue of this study is the regional modelling description of a continent where a huge variety of climates are present, from desert to mountain conditions, and from tropical to subtropical regimes. Another basic objective of this preliminary work is also to obtain a measure of the spread among

  16. Switzerland: current energy and climate policies. Political boundary conditions

    International Nuclear Information System (INIS)

    End use energy consumption in Switzerland has increased almost ninefold over the past 95 years, amounting to nearly 88 PJ in 2004. This figure breaks down as follows: coal 5%, oil-based fuels 29%, motor fuels 31%, electricity 22%, gas 11%, district heat, solid municipal and industrial waste as well as renewables (excluding electricity) approx. 1%. In 2004 alone, end use energy consumption rose by half a percent, thus reaching a new record high. This development is due, above all, to the population increase and to economic growth. To achieve its goals in energy and climate policies, and to initiate sustainable energy supply, the Swiss federal council in 2001 launched the 'EnergySwitzerland' Program. The new strategy of the Program focuses on these three goals: 'Climate', 'Electricity: Efficiency Goal', and 'Renewable Energies'. On the basis of perspectives of the development of the population and of the economy, the consequences of a number of policy variants for energy supply and demand and for the economy and the environment have been examined. Four scenarios (variants) are to help design energy policy on a medium and long term by showing energy policy options. For the area of electricity supply facing increasing requirements, 4 options and their pros and cons are distinguished: electricity imports, renewable energies, fossil- fired thermal plants (combined-cycle plants), and nuclear power. With a 40% share in domestic production, nuclear power continues to be a pillar of Swiss energy supply. The fundamental question about the future of nuclear power is not a question of technical or economic know-how, but a question of the system of political values. As the current legal system in the field of electricity supply does not meet requirements, it will have to be adapted. (orig.)

  17. Impact of future climatic conditions on the potential for soil organic matter priming

    DEFF Research Database (Denmark)

    Reinsch, Sabine; Ambus, Per; Thornton, Barry;

    2013-01-01

    Terrestrial carbon (C) storage and turnover are of major interest under changing climatic conditions. We present a laboratory microcosm study investigating the effects of anticipated climatic conditions on the soil microbial community and related changes in soil organic matter (SOM) decomposition...... using chloroform fumigation extraction, and compound-specific phospholipid fatty acid analysis was used to determine microbial community composition and substrate use. We observed that glucose additions induced SOM priming in ambient and eCO2 treated soils, but not in soil exposed to future climatic...

  18. Impact of climate and analysis of desertification processes in semi arid land in Algeria: using data of Alsat-1 and Landsat

    Science.gov (United States)

    Ahmed, Z.; Habib, M.; Sid Ali, H.; Sofiane, K.

    2015-04-01

    The degradation of natural resources in arid and semi-arid areas was highlighted dramatically during this century due to population growth and transformation of land use systems. The Algerian steppe has undergone a regression over the past decade due to drought cycle, the extension of areas cultivated in marginal lands, population growth and overgrazing. These phenomena have led to different degradation processes, such as the destruction of vegetation, soil erosion, and deterioration of the physical environment. In this study, the work is mainly based on the criteria for classification and identification of physical parameters for spatial analysis, and multi-sources factors to determine the vulnerability of steppe formations and their impact on desertification. To do this, we used satellite data Alsat-1 (2009) IRS (2009) and LANDSAT TM (2001). These cross-sectional data with exogenous information could monitor the impact of the semi arid ecological diversity of steppe formations. A hierarchical process including the supervised image classification was used to characterize the main steppe formations. An analysis of the vulnerability of plant was conducted to assign weights and identify areas most susceptible to desertification. Vegetation indices combined with classification are used to characterize the forest and steppe formations to determine changes in land use. The results of this present study provide maps of different components of the steppe, formation that could assist in highlighting the magnitude of the degradation pathways, which affects the steppe environment, allowing an analysis of the process of desertification in the region.

  19. 宁夏中部干旱带天然草地气候生产潜力研究%Potential Climatic Productivity of Natural Grassland in the Middle Arid Zone of Ningxia

    Institute of Scientific and Technical Information of China (English)

    马甜; 王俊波; 张治华; 徐秀梅

    2013-01-01

    The annual potential productivity of grassland in the middle arid zone of Ningxia during 1975 to 2006 was estimated according to the ten-day period temperature and precipitation of these years (1975 - 2010) recorded by 10 meteorological observatories using Miami model and Thornthwaite Memorial model. The objects were to analyze the change regulation of the potential climatic productivity and provide a theoretical basis for improving grassland and increasing vegetation. Results showed that the climate in the middle arid zone of Ningxia had a change tendency toward "warm dry". The inter-annual variation range of the grassland potential climatic productivity was 2668. 56~7499. 53 kg · hm-2 · a-1 and the potentiality was large. The grassland potential climatic productivity increased or decreased 58. 68 kg · hm-2 · a-1 with the maximum temperature increasing or decreasing 1℃. The grassland potential climatic productivity increased or decreased 18. 64 kg · hm-2 · a-1 with the annual precipitation increasing or decreasing 1 mm. The annual precipitation and potential climatic productivity in the middle arid zone of Ningxia had an extremely significant linear correlation and the correlation coefficient was 0. 984 ~0. 997, whereas the average annual temperature and potential climatic productivity did not have a significant correlation. Therefore, the natural tolerance, namely potential climatic productivity of the natural grassland of the area, should be considered when planting.%依据宁夏中部干旱带同心县、盐池县等10个代表性气象台站36年(1975-2010年)逐旬气温、降水资料,基于Miami模型和Thornthwaite Memorial模型对宁夏中部干旱带1975-2006年间草地生产潜力作估算,并分析其变化规律,旨在为改良草地、植被恢复提供理论依据.结果表明:宁夏中部干旱带气候具有向“暖干化”变化的趋势,草地气候生产潜力年际变化范围为2668.56~7499.53kg·hm-2·a-1,气候生产潜力较

  20. Evaluation of the transferability of hydrological model parameters for simulations under changed climatic conditions

    Directory of Open Access Journals (Sweden)

    S. Bastola

    2011-06-01

    Full Text Available Conceptual hydrological models are widely used for climate change impact assessment. The implicit assumption in most such work is that the parameters estimated from observations remain valid for future climatic conditions. This paper evaluates a simple threshold based approach for testing this assumption, where a set of behavioural simulators are identified for different climatic conditions for the future simulation i.e. wet, average and dry conditions. These simulators were derived using three different data sets that are generated by sampling a block of one year of data without replacement from the observations such that they define the different climatic conditions. The simulators estimated from the wet climatic data set showed the tendency to underestimate flow when applied to dry data set and vice versa. However, the performances of the three sets of basin simulators on chronologically coherent data are identical to the simulators identified from a sufficiently long data series that contains both wet and dry climatic conditions. The results presented suggest that the issue of time invariance in the value of parameters has a minimal effect on the simulation if the change in precipitation is less than 10 % of the data used for calibration.

  1. Catchment sensitivity to changing climate conditions: the importance of landscape characteristic

    Science.gov (United States)

    Teutschbein, C.; Karlsen, R.; Grabs, T.; Laudon, H.; Bishop, K. H.

    2014-12-01

    The scientific literature is full of studies analyzing future climate change impacts on hydrology with focus on individual catchments. However, we recently found that hydrologic behavior and specific discharge vary considerably even in neighboring and rather similar catchments under current climate conditions and that these variations are related to landscape characteristics. Therefore we hypothesize that these landscape characteristics also play a fundamental role for the sensitivity of a catchment to changing climate conditions. We analyzed the hydrological response of 14 neighboring catchments in Northern Sweden with slightly different topography, land cover, size and geology. Current (1981-2010) and future (2061-2090) streamflow was simulated with the HBV light model. Climate projections were based on 14 regional climate models (ENSEMBLES EU project) and bias-corrected with a distribution-mapping approach. Our simulations revealed that future spring flood peaks will occur much earlier and decrease by 13 to 32 %, whereas winter base flows will increase slightly. These changes are somewhat expected and mainly triggered by a projected increase in winter temperature, which leads to less snow accumulation on the ground. However, these values also highlight that there is a large variability amongst the catchments in their hydrological response to the same future climate conditions. For example, spring flood peaks in catchments without wetlands decrease by only 13 to 15 %, whereas catchments with wetlands show a spring flood peak reduction of 20 to 32 %. In addition to wetlands, we also identified lakes, peat soils and higher elevations as factors that seem to cause a stronger hydrological response to the climate change signal, whereas catchments dominated by forests, steeper slopes and till soils seem to be less strongly affected by a changing climate. Therefore, our results suggest that the sensitivity of catchments to future climate conditions is strongly linked to

  2. Hydrological Responses to Land-Use Change Scenarios under Constant and Changed Climatic Conditions

    Science.gov (United States)

    Zhang, Ling; Nan, Zhuotong; Yu, Wenjun; Ge, Yingchun

    2016-02-01

    This study quantified the hydrological responses to land-use change scenarios in the upper and middle Heihe River basin (HRB), northwest China, under constant and changed climatic conditions by combining a land-use/cover change model (dynamic conversion of land use and its effects, Dyna-CLUE) and a hydrological model (soil and water assessment tool, SWAT). Five land-use change scenarios, i.e., historical trend (HT), ecological protection (EP), strict ecological protection (SEP), economic development (ED), and rapid economic development (RED) scenarios, were established. Under constant climatic condition, hydrological variations are only induced by land-use changes in different scenarios. The changes in mean streamflow at the outlets of the upper and the middle HRB are not pronounced, although the different scenarios produce different outcomes. However, more pronounced changes are observed on a subbasin level. The frequency of extreme flood is projected to decrease under the SEP scenario, while under the other scenarios, no changes can be found. Two emission scenarios (A1B and B1) of three general circulation models (HadCM3, CGCM3, and CCSM3) were employed to generate future possible climatic conditions. Under changed climatic condition, hydrological variations are induced by the combination of land-use and climatic changes. The results indicate that the impacts of land-use changes become secondary when the changed climatic conditions have been considered. The frequencies of extreme flood and drought are projected to decrease and increase, respectively, under all climate scenarios. Although some agreements can be reached, pronounced difference of hydrological responses can be observed for different climate scenarios of different GCMs.

  3. Hydrological Responses to Land-Use Change Scenarios under Constant and Changed Climatic Conditions.

    Science.gov (United States)

    Zhang, Ling; Nan, Zhuotong; Yu, Wenjun; Ge, Yingchun

    2016-02-01

    This study quantified the hydrological responses to land-use change scenarios in the upper and middle Heihe River basin (HRB), northwest China, under constant and changed climatic conditions by combining a land-use/cover change model (dynamic conversion of land use and its effects, Dyna-CLUE) and a hydrological model (soil and water assessment tool, SWAT). Five land-use change scenarios, i.e., historical trend (HT), ecological protection (EP), strict ecological protection (SEP), economic development (ED), and rapid economic development (RED) scenarios, were established. Under constant climatic condition, hydrological variations are only induced by land-use changes in different scenarios. The changes in mean streamflow at the outlets of the upper and the middle HRB are not pronounced, although the different scenarios produce different outcomes. However, more pronounced changes are observed on a subbasin level. The frequency of extreme flood is projected to decrease under the SEP scenario, while under the other scenarios, no changes can be found. Two emission scenarios (A1B and B1) of three general circulation models (HadCM3, CGCM3, and CCSM3) were employed to generate future possible climatic conditions. Under changed climatic condition, hydrological variations are induced by the combination of land-use and climatic changes. The results indicate that the impacts of land-use changes become secondary when the changed climatic conditions have been considered. The frequencies of extreme flood and drought are projected to decrease and increase, respectively, under all climate scenarios. Although some agreements can be reached, pronounced difference of hydrological responses can be observed for different climate scenarios of different GCMs. PMID:26429363

  4. Energy performance of solar-assisted liquid desiccant air-conditioning system for commercial building in main climate zones

    International Nuclear Information System (INIS)

    Highlights: • Simulation of solar liquid desiccant AC system in four climate regions was conducted. • System performance was determined by relationship of sensible and latent cooling load. • For humid area, saving amount is large by handling latent load with solar energy. • For dry area, electricity saving rate is considerable due to the high COP of chillers. • For buildings with mild SHR, the system performance was not as good as others. - Abstract: Liquid desiccant air-conditioning (LDAC) system, which consists of a liquid desiccant ventilation system for dehumidification and an air-handling unit for cooling, has become a promising alternative for conventional technology. To evaluate its feasibility and applicability, the simulation of solar-assisted LDAC (SLDAC) in commercial buildings in five cities of four main climate regions were conducted, including Singapore in Tropical, Houston and Beijing in Temperate, Boulder in Arid and Los Angeles in Mediterranean. Results showed that the system’s performance was seriously affected by the ratios of building’s sensible and latent cooling load. For buildings located in humid areas with low sensible-total heat ratio (SHR), the electricity energy reduction of SLDAC was high, about 450 MW h in Houston and Singapore, which accounted for 40% of the total energy consumption in cooling seasons. The cost payback period was as short as approximately 7 years. The main reason is that the energy required for handling the moisture could be saved by liquid desiccant dehumidification, and the regeneration heat could be covered by solar collectors. For buildings in dry climate with high SHR, the total cooling load was low, but up to 45% electricity of AC system could be saved in Boulder because the chiller COP could be significantly improved during more than 70% operation time. The cost payback period was around 22 years, which was acceptable. However, for the buildings with mild SHR, such as those in Beijing and Los

  5. Evaluation of thermal perception in schoolyards under Mediterranean climate conditions

    Science.gov (United States)

    Antoniadis, D.; Katsoulas, N.; Papanastasiou, D.; Christidou, V.; Kittas, C.

    2016-03-01

    The aim of this paper was to study qualitatively and quantitatively the thermal perception and corresponding heat stress conditions that prevail in two schoolyards in a coastal city in central Greece. For this purpose, meteorological parameters (i.e., wind speed, temperature, relative humidity, solar radiation) were recorded at 70 and 55 measuring points in the schoolyards, from 14:00 to 15:30 local time, during May and June of 2011. The measuring points were distributed so as to get measurements at points (a) directly exposed to the sun, (b) under the shadow of trees and building structures, and (c) near building structures. Cluster analysis was applied to group observations and revealed places that are microclimatically homogeneous. Thermal perception and heat stress conditions were assessed by means of the physiologically equivalent temperature (PET, °C), and the results are presented in relevant charts. The impact of material's albedo, radiation's reflection by structures and obstacles, and different tree species on thermal perception and heat stress conditions was also assessed. The analysis showed that trees triggered a reduction of incident solar radiation that ranged between 79 and 94 % depending on tree's species, crown dimension, tree height, and leaf area. PET values were mainly affected by solar radiation and wind speed. Trees caused a reduction of up to 37 % in PET values, while a 1-m s-1 increase in wind speed triggered a reduction of 3.7-5.0 °C in PET value. The effective shading area in the two schoolyards was small, being 27.5 and 11 %. The results of this study could be exploited by urban planning managers when designing or improving the outdoor environment of a school complex.

  6. Evaluation of thermal perception in schoolyards under Mediterranean climate conditions.

    Science.gov (United States)

    Antoniadis, D; Katsoulas, N; Papanastasiou, D; Christidou, V; Kittas, C

    2016-03-01

    The aim of this paper was to study qualitatively and quantitatively the thermal perception and corresponding heat stress conditions that prevail in two schoolyards in a coastal city in central Greece. For this purpose, meteorological parameters (i.e., wind speed, temperature, relative humidity, solar radiation) were recorded at 70 and 55 measuring points in the schoolyards, from 14:00 to 15:30 local time, during May and June of 2011. The measuring points were distributed so as to get measurements at points (a) directly exposed to the sun, (b) under the shadow of trees and building structures, and (c) near building structures. Cluster analysis was applied to group observations and revealed places that are microclimatically homogeneous. Thermal perception and heat stress conditions were assessed by means of the physiologically equivalent temperature (PET, °C), and the results are presented in relevant charts. The impact of material's albedo, radiation's reflection by structures and obstacles, and different tree species on thermal perception and heat stress conditions was also assessed. The analysis showed that trees triggered a reduction of incident solar radiation that ranged between 79 and 94 % depending on tree's species, crown dimension, tree height, and leaf area. PET values were mainly affected by solar radiation and wind speed. Trees caused a reduction of up to 37 % in PET values, while a 1-m s(-1) increase in wind speed triggered a reduction of 3.7-5.0 °C in PET value. The effective shading area in the two schoolyards was small, being 27.5 and 11 %. The results of this study could be exploited by urban planning managers when designing or improving the outdoor environment of a school complex. PMID:26190284

  7. Study of Saudi Arabian climatic conditions using Hurst exponent and climatic predictability index

    International Nuclear Information System (INIS)

    This paper utilizes Hurst exponent to study the persistency of meteorological parameters individually and dependency of rainfall/precipitation on pressure and temperature using climate predictability index. For the purpose, daily averages of surface pressure and temperature and daily total rainfall data for a period of 7 years for three locations and 14 years for seven locations has been utilized. The Hurst exponents (H) for above mentioned meteorological parameters were calculated using rescaled range analysis (R/S) and absolute moments methods. These H values were used to calculate the fractal dimension D for pressure, temperature and rainfall data. Finally, these D's were used to calculate the climate predictability index PIC in terms of pressure predictability index (PIP), temperature predictability index (PIT) and rainfall predictability index (PIR). The Hurst exponent analysis showed that H values for rainfall, relative humidity and wind speed time series data for all the stations were >0.5 which is indicative of persistence behavior of the parameters on the previous values while for pressure and temperature H values were <0.5 means anti-persistence behavior. The climate predictability index showed that in most of the cases the rainfall was dependent on both pressure and temperature predictability indices. In some cases it was more dependent on pressure index than the temperature and in some cases otherwise. In Saudi Arabia there is no prevalent or established rainy season and the present analysis could not result into concrete results. It is therefore recommended to analyze the data by breaking the entire data set into seasons and further into different years.

  8. Climate change and land management impact rangeland condition and sage-grouse habitat in southeastern Oregon

    Directory of Open Access Journals (Sweden)

    Megan K. Creutzburg

    2015-04-01

    Full Text Available Contemporary pressures on sagebrush steppe from climate change, exotic species, wildfire, and land use change threaten rangeland species such as the greater sage-grouse (Centrocercus urophasianus. To effectively manage sagebrush steppe landscapes for long-term goals, managers need information about the potential impacts of climate change, disturbances, and management activities. We integrated information from a dynamic global vegetation model, a sage-grouse habitat climate envelope model, and a state-and-transition simulation model to project broad-scale vegetation dynamics and potential sage-grouse habitat across 23.5 million acres in southeastern Oregon. We evaluated four climate scenarios, including continuing current climate and three scenarios of global climate change, and three management scenarios, including no management, current management and a sage-grouse habitat restoration scenario. All climate change scenarios projected expansion of moist shrub steppe and contraction of dry shrub steppe, but climate scenarios varied widely in the projected extent of xeric shrub steppe, where hot, dry summer conditions are unfavorable for sage-grouse. Wildfire increased by 26% over the century under current climate due to exotic grass encroachment, and by two- to four-fold across all climate change scenarios as extreme fire years became more frequent. Exotic grasses rapidly expanded in all scenarios as large areas of the landscape initially in semi-degraded condition converted to exotic-dominated systems. Due to the combination of exotic grass invasion, juniper encroachment, and climatic unsuitability for sage-grouse, projected sage-grouse habitat declined in the first several decades, but increased in area under the three climate change scenarios later in the century, as moist shrub steppe increased and rangeland condition improved. Management activities in the model were generally unsuccessful in controlling exotic grass invasion but were

  9. Climatic conditions governing extensive Azolla bloom during the Middle Eocene

    Science.gov (United States)

    Dekker, Rolande; Speelman, Eveline N.; Barke, Judith; Konijnendijk, Tiuri; Sinninge Damste, Jaap S.; Reichart, Gert-Jan

    2010-05-01

    Enormous amounts of intact mega- and microspores from the free floating aquatic fern Azolla were found in sediments recovered during Integrated Ocean Drilling Program expedition 302, indicating that Azolla grew and reproduced in situ in the Eocene Arctic Ocean. In general, the Early/Middle Eocene is characterized by enhanced greenhouse conditions with elevated sea surface temperatures (SSTs) in the Arctic (~10°C), while tropical sea surface temperatures (SSTs) were only a little warmer than today (with a mean annual temperature (MAT) of 32-34 °C) (Pearson et al., 2007). The consequently reduced temperature gradient between the equator and the poles and the presence of freshwater at the North Pole as indicated by the presence of the freshwater fern Azolla (Brinkhuis et al., 2006) provide important boundary conditions for understanding the hydrological cycle and latent heat transport during this interval. Here we reconstruct variations in SST and mean annual air temperature using the TEX86 and MBT temperature proxies for the Azolla interval. Sediments from around the Arctic Basin have been analyzed, including samples from Alaska, the Mackenzie Basin, Greenland (IODP core 913b), and Denmark. Furthermore, a high resolution sea surface temperature record for the Azolla interval has been constructed from sediment samples from the Lomonosov Ridge, showing a cyclic signal. Model experiments have shown that the here confirmed low equator-to-pole temperature gradient modulated the hydrological cycle. Since the growth of Azolla is restricted to low salinity conditions, changes in the hydrological cycle are proposed to coincide with the cyclic occurrence of Azolla throughout the interval. To confirm the overlapping presence of high quantities of Azolla and increased precipitation, changes in the hydrogen cycle are reconstructed by creating a high resolution hydrogen isotope record throughout the interval. By performing compound specific analyses (δD) on terrestrial derived

  10. Attributing Climate Conditions for Stable Malaria Transmission to Human Activity in sub-Saharan Africa

    Science.gov (United States)

    Sheldrake, L.; Mitchell, D.; Allen, M. R.

    2015-12-01

    Temperature and precipitation limit areas of stable malaria transmission, but the effects of climate change on the disease remain controversial. Previously, studies have not separated the influence of anthropogenic climate change and natural variability, despite being an essential step in the attribution of climate change impacts. Ensembles of 2900 simulations of regional climate in sub-Saharan Africa for the year 2013, one representing realistic conditions and the other how climate might have been in the absence of human influence, were used to force a P.falciparium climate suitability model developed by the Mapping Malaria Risk in Africa project. Strongest signals were detected in areas of unstable transmission, indicating their heightened sensitivity to climatic factors. Evidently, impacts of human-induced climate change were unevenly distributed: the probability of conditions being suitable for stable malaria transmission were substantially reduced (increased) in the Sahel (Greater Horn of Africa (GHOA), particularly in the Ethiopian and Kenyan highlands). The length of the transmission season was correspondingly shortened in the Sahel and extended in the GHOA, by 1 to 2 months, including in Kericho (Kenya), where the role of climate change in driving recent malaria occurrence is hotly contested. Human-induced warming was primarily responsible for positive anomalies in the GHOA, while reduced rainfall caused negative anomalies in the Sahel. The latter was associated with anthropogenic impacts on the West African Monsoon, but uncertainty in the RCM's ability to reproduce precipitation trends in the region weakens confidence in the result. That said, outputs correspond well with broad-scale changes in observed endemicity, implying a potentially important contribution of anthropogenic climate change to the malaria burden during the past century. Results support the health-framing of climate risk and help indicate hotspots of climate vulnerability, providing

  11. Sustainability Challenges from Climate Change and Air Conditioning Use in Urban Areas

    OpenAIRE

    Karin Lundgren; Tord Kjellstrom

    2013-01-01

    Global climate change increases heat loads in urban areas causing health and productivity risks for millions of people. Inhabitants in tropical and subtropical urban areas are at especial risk due to high population density, already high temperatures, and temperature increases due to climate change. Air conditioning is growing rapidly, especially in South and South-East Asia due to income growth and the need to protect from high heat exposures. Studies have linked increased total hourly elect...

  12. Climatic Conditions and Productivity: An Impact Evaluation in Pre-industrial England

    OpenAIRE

    Stéphane Auray; Aurélien Eyquem; Frédéric Jouneau-Sion

    2014-01-01

    In this paper, we bridge economic data and climatic time series to assess the vulnerability of a pre-industrial economy to changes in climatic conditions. We propose an economic model to extract a measure of total productivity from English data (real wages and land rents) in the pre-industrial period. This measure of total productivity is then related to temperatures and precipitations. We find that lower (respectively higher) precipitations (resp. temperatures) enhance productivity. Further,...

  13. Climatic Conditions and Productivity: An Impact Evaluation in Pre-industrial England

    OpenAIRE

    Auray, Stéphane; Eyquem, Aurélien; Jouneau-Sion, Frédéric

    2014-01-01

    In this paper, we bridge economic data and climatic time series to assess the vulnerability of a pre-industrial economy to changes in climatic conditions. We propose an economic model to extract a measure of total productivity from English data (real wages and land rents) in the pre-industrial period. This measure of total productivity is then related to temperatures and precipitations. We find that lower (respectively higher) than average precipitations (respectively temperatures) enhance pr...

  14. Climatic Conditions for modelling the Northern Hemisphere ice sheets throughout the ice age cycle

    OpenAIRE

    Abe-Ouchi, A.; Segawa, T; F. Saito

    2007-01-01

    The ice sheet-climate interaction as well as the climatic response to orbital parameters and atmospheric CO2 content are examined in order to drive an ice sheet model throughout an ice age cycle. Feedback processes between ice sheet and atmosphere are analyzed by numerical experiments using a high resolution General Circulation Model (GCM) under different conditions at the Last Glacial Maximum. Among the proposed processes, the ice albedo feedback, the elevation-mass ba...

  15. Modeling of hydrologic conditions and solute movement in processed oil shale waste embankments under simulated climatic conditions

    International Nuclear Information System (INIS)

    The scope of this program is to study interacting hydrologic, geotechnical, and chemical factors affecting the behavior and disposal of combusted processed oil shale. The research combines bench-scale testing with large scale research sufficient to describe commercial scale embankment behavior. The large scale approach was accomplished by establishing five lysimeters, each 7.3 x 3.0 x 3.0 m deep, filled with processed oil shale that has been retorted and combusted by the Lurgi-Ruhrgas (Lurgi) process. Approximately 400 tons of Lurgi processed oil shale waste was provided by RBOSC to carry out this study. Research objectives were designed to evaluate hydrologic, geotechnical, and chemical properties and conditions which would affect the design and performance of large-scale embankments. The objectives of this research are: assess the unsaturated movement and redistribution of water and the development of potential saturated zones and drainage in disposed processed oil shale under natural and simulated climatic conditions; assess the unsaturated movement of solubles and major chemical constituents in disposed processed oil shale under natural and simulated climatic conditions; assess the physical and constitutive properties of the processed oil shale and determine potential changes in these properties caused by disposal and weathering by natural and simulated climatic conditions; assess the use of previously developed computer model(s) to describe the infiltration, unsaturated movement, redistribution, and drainage of water in disposed processed oil shale; evaluate the stability of field scale processed oil shale solid waste embankments using computer models

  16. Keeping Sediment and Nutrients out of Streams in Arid/Semi-Arid Regions: Application of Low Impact Development/Green Infrastructure Practices

    Science.gov (United States)

    Yongping, Yuan

    2015-04-01

    Climatic and hydrological characteristics in the arid/semi-arid areas create unique challenges to soil, water and biodiversity conservation. These areas are environmentally sensitive, but very valuable for the ecosystems services they provide to society. Some of these areas are experiencing the fastest urbanization and now face multiple water resource challenges. Low Impact Development (LID)/Green Infrastructure (GI) practices are increasingly popular for reducing stormwater and nonpoint source pollution in many regions around the world. However, streamflow in the arid/semi-arid regions is largely dependent on seasonal, short term, and high intensity rainfall events. LID has not been very common in the arid/semi-arid regions due to a lack of performance evaluation, as well as the perception that LID may not be very useful for regions with little annual precipitation. This study focused on investigating the hydrologic and pollutant removal performance of LID/GI systems in arid/semi-arid climates. Ten types of practices were found in use in the Western/Southwestern U.S.: rainwater harvest systems, detention ponds, retention ponds, bioretention, media filters, porous pavements, vegetated swales/buffer/strips, green roofs, infiltration trenches, and integrated LIDs. This study compared the performance of these practices in terms of their effectiveness at pollutant removal and cost-effectiveness. This analysis provides insight into the future implementation of LID/GI in the arid/semi-arid areas. Key words: LID/GI, arid/semi-arid, effectiveness of pollutant removal, cost-effectiveness analysis

  17. Glacial aridity in central Indonesia coeval with intensified monsoon circulation

    Science.gov (United States)

    Konecky, Bronwen; Russell, James; Bijaksana, Satria

    2016-03-01

    The Last Glacial Maximum was cool and dry over the Indo-Pacific Warm Pool (IPWP), a key region driving global oceanic-atmospheric circulation. Both low- and high-latitude teleconnections with insolation, ice sheets, and sea level have been suggested to explain the pervasive aridity observed in paleoecological and geomorphic data. However, proxies tracking the H- and O-isotopic composition of rainfall (e.g., speleothems, sedimentary biomarkers) suggest muted aridity or even wetter conditions than the present, complicating interpretations of glacial IPWP climate. Here we use multiproxy reconstructions from lake sediments and modern rainfall isotopic measurements from central Indonesia to show that, contrary to the classical "amount effect," intensified Australian-Indonesian monsoon circulation drove lighter H- and O-isotopic composition of IPWP rainfall during the LGM, while at the same time, dry conditions prevailed. Precipitation isotopes are particularly sensitive to the apparent increase in monsoon circulation and perhaps also decreased moisture residence time implied by our data, explaining contrasts among proxy records while illuminating glacial IPWP atmospheric circulation, a key target for climate models.

  18. Global patterns and environmental controls of perchlorate and nitrate co-occurrence in arid and semi-arid environments

    Science.gov (United States)

    Jackson, W. Andrew; Böhlke, J. K.; Andraski, Brian J.; Fahlquist, Lynne; Bexfield, Laura; Eckardt, Frank D.; Gates, John B.; Davila, Alfonso F.; McKay, Christopher P.; Rao, Balaji; Sevanthi, Ritesh; Rajagopalan, Srinath; Estrada, Nubia; Sturchio, Neil; Hatzinger, Paul B.; Anderson, Todd A.; Orris, Greta; Betancourt, Julio; Stonestrom, David; Latorre, Claudio; Li, Yanhe; Harvey, Gregory J.

    2015-09-01

    Natural perchlorate (ClO4-) is of increasing interest due to its wide-spread occurrence on Earth and Mars, yet little information exists on the relative abundance of ClO4- compared to other major anions, its stability, or long-term variations in production that may impact the observed distributions. Our objectives were to evaluate the occurrence and fate of ClO4- in groundwater and soils/caliche in arid and semi-arid environments (southwestern United States, southern Africa, United Arab Emirates, China, Antarctica, and Chile) and the relationship of ClO4- to the more well-studied atmospherically deposited anions NO3- and Cl- as a means to understand the prevalent processes that affect the accumulation of these species over various time scales. ClO4- is globally distributed in soil and groundwater in arid and semi-arid regions on Earth at concentrations ranging from 10-1 to 106 μg/kg. Generally, the ClO4- concentration in these regions increases with aridity index, but also depends on the duration of arid conditions. In many arid and semi-arid areas, NO3- and ClO4- co-occur at molar ratios (NO3-/ClO4-) that vary between ∼104 and 105. We hypothesize that atmospheric deposition ratios are largely preserved in hyper-arid areas that support little or no biological activity (e.g. plants or bacteria), but can be altered in areas with more active biological processes including N2 fixation, N mineralization, nitrification, denitrification, and microbial ClO4- reduction, as indicated in part by NO3- isotope data. In contrast, much larger ranges of Cl-/ClO4- and Cl-/NO3- ratios indicate Cl- varies independently from both ClO4- and NO3-. The general lack of correlation between Cl- and ClO4- or NO3- implies that Cl- is not a good indicator of co-deposition and should be used with care when interpreting oxyanion cycling in arid systems. The Atacama Desert appears to be unique compared to all other terrestrial locations having a NO3-/ClO4- molar ratio ∼103. The relative

  19. Desertification of arid Rangelands in Morocco

    OpenAIRE

    Mahyou, Hamid; Tychon, Bernard; Paul, Roger; Balaghi, Riad; Mimouni, Jamal

    2011-01-01

    Rangeland or natural arid pastures of Morocco are ecosystems where there is a natural or seminatural vegetation composed of steppes, shrubs and grassland. They cover about 82% of the Moroccan arid lands. These areas represent livelihoods for thousands of people and protect the country from desertification. Despite the importance of the rangelands and the threat of desertification, it is surprising that up to date there is no comprehensive assessment of their condition ...

  20. 中中新世中亚构造抬升驱动气候干旱化:以塔里木盆地东南缘江尕勒萨伊剖面为例%Uplift-driven climatic aridity during the middle Miocene:A case study of the Janggalsay section, southeast Tarim Basin

    Institute of Scientific and Technical Information of China (English)

    卢海建; 李海兵; 刘栋梁

    2014-01-01

    the central Asia. As the timing of intensification of climatic aridity (16-12 Ma) is inconsistent with the onset age of global cooling (about 14 Ma), that of the attainment of a threshold elevation in the southern Tibetan Plateau (≥40 Ma), and that of the retreat of the Paratethys from the central Asia (>34 Ma), the authors hold that these three factors may be only important boundary conditions or favorable auxiliary conditions for the intensification of aridity during the middle Miocene. Previous studies of the Janggalsay strata on the southeast margin of the Tarim Basin indicated that the rapid uplift of the Altun Mountains occurred at~16 Ma. Combined with new magnetostratigraphic ages, the published carbon and oxygen isotopes data suggest a gradual intensification of climatic aridity since ~16 Ma for the Janggalsay area. Based on the simultaneous relationship, the authors attribute the middle Miocene increasing aridity to the rapid uplift of the Altun Mountains. Viewed from a broader context, the Mid-Miocene crustal shortening deformation is extensively existent within Central Asia. The multi-proxy analysis of red clay in China’s loess plateau and eolian dust from the northern Pacific Ocean indicates that the middle Miocene tectonic uplift and accompanying rain shadow effect acted as the major mechanism in driving the increased aridity in Central Asia.

  1. Key factors affecting urban runoff pollution under cold climatic conditions

    Science.gov (United States)

    Valtanen, Marjo; Sillanpää, Nora; Setälä, Heikki

    2015-10-01

    Urban runoff contains various pollutants and has the potential of deteriorating the quality of aquatic ecosystems. In this study our objective is to shed light on the factors that control the runoff water quality in urbanized catchments. The effects of runoff event characteristics, land use type and catchment imperviousness on event mass loads (EML) and event mean concentrations (EMC) were studied during warm and cold periods in three study catchments (6.1, 6.5 and 12.6 ha in size) in the city of Lahti, Finland. Runoff and rainfall were measured continuously for two years at each catchment. Runoff samples were taken for total nutrients (tot-P and tot-N), total suspended solids (TSS), heavy metals (Zn, Cr, Al, Co, Ni, Cu, Pb, Mn) and total organic carbon (TOC). Stepwise multiple linear regression analysis (SMLR) was used to identify general relationships between the following variables: event water quality, runoff event characteristics and catchment characteristics. In general, the studied variables explained 50-90% of the EMLs but only 30-60% of the EMCs, with runoff duration having an important role in most of the SMLR models. Mean runoff intensity or peak flow was also often included in the runoff quality models. Yet, the importance (being the first, second or third best) and role (negative or positive impact) of the explanatory variables varied between the cold and warm period. Land use type often explained cold period concentrations, but imperviousness alone explained EMCs weakly. As for EMLs, the influence of imperviousness and/or land use was season and pollutant dependent. The study suggests that pollutant loads can be - throughout the year - adequately predicted by runoff characteristics given that seasonal differences are taken into account. Although pollutant concentrations were sensitive to variation in seasonal and catchment conditions as well, the accurate estimation of EMCs would require a more complete set of explanatory factors than used in this

  2. Prediction of thermal sensation in non-air-conditioned buildings in warm climates

    DEFF Research Database (Denmark)

    Fanger, Povl Ole; Toftum, Jørn

    2002-01-01

    The PMV model agrees well with high-quality field studies in buildings with HVAC systems, situated in cold, temperate and warm climates, studied during both summer and winter. In non-air-conditioned buildings in warm climates, occupants may sense the warmth as being less severe than the PMV...... predicts. The main reason is low expectations, but a metabolic rate that is estimated too high can also contribute to explaining the difference. An extension of the PMV model that includes an expectancy factor is introduced for use in non-air-conditioned buildings in warm climates. The extended PMV model...... agrees well with quality field studies in non-air-conditioned buildings of three continents....

  3. Extension of the PMV model to non-air-conditioned building in warm climates

    DEFF Research Database (Denmark)

    Fanger, Povl Ole; Toftum, Jørn

    2002-01-01

    The PMV model agrees well with high-quality field studies in buildings with HVAC systems, situated in cold, temperate and warm climates, studied during both summer and winter. In non-air-conditioned buildings in warm climates, occupants may sense the warmth as being less severe than the PMV...... predicts. The main reason is low expectations, but a metabolic rate that is estimated too high can also contribute to explaining the difference. An extension of the PMV model that includes an expectancy factor is introduced for use in non-air-conditioned buildings in warm climates. The extended PMV model...... agrees well with quality field studies in non-air-conditioned buildings of three continents....

  4. Great Basin semi-arid woodland dynamics during the late quaternary

    Energy Technology Data Exchange (ETDEWEB)

    Wigand, P.E.; Hemphill, M.L.; Sharpe, S.E. [Univ. and Community College System of Nevada, Reno, NV (United States)] [and others

    1995-09-01

    Semi-arid woodlands have dominated the middle elevations of Great Basin mountain ranges during the Holocene where subalpine woodlands prevailed during the Pleistocene. Ancient woodrat middens, and in a few cases pollen records indicate in the late Pleistocene and early Holocene woodland history lowered elevation of subalpine woodland species. After a middle Holocene retrenchment at elevations in excess of 500 meters above today, Juniper-dominated semi-arid woodland reached its late Holocene maximum areal extent during the Neoglacial (2 to 4 ka). These records, along with others indicate contracting semi-arid woodland after the Neoglacial about 1.9 ka. Desert shrub community expansion coupled with increased precariousness of wetland areas in the southern Great Basin between 1.9 and 1.5 ka coincide with shrinking wet-lands in the west-central and northern Great Basin. Coincident greater grass abundance in northern Great Basin sagebrush steppe, reaching its maximum between 1.5 and 1.2 ka, corresponds to dramatic increases in bison remains in the archaeological sites of the northern Intermontane West. Pollen and woodrat midden records indicate that this drought ended about 1.5 ka. Succeeding ameliorating conditions resulted in the sudden northward and downward expansion of pinon into areas that had been dominated by juniper during the Neoglacial. Maximum areal extent of pinon dominated semi-arid woodland in west-central Nevada was centered at 1.2 ka. This followed by 100 years the shift in dominance from juniper to pinon in southern Nevada semi-arid woodlands. Great Basin woodlands suffered from renewed severe droughts between .5 to .6 ka. Effectively wetter conditions during the {open_quotes}Little Ice Age{close_quotes} resulted in re-expansion of semi-arid woodland. Activities related to European settlement in the Great Basin have modified prehistoric factors or imposed new ones that are affecting woodland response to climate.

  5. Catchment Sensitivity to Changing Climate Conditions: The Importance of Landscape Characteristics

    Science.gov (United States)

    Teutschbein, Claudia; Karlsen, Reinert; Grabs, Thomas; Laudon, Hjalmar; Bishop, Kevin

    2015-04-01

    The scientific literature is full of studies analyzing future climate change impacts on hydrology with focus on individual catchments. We recently found, however, that hydrologic behavior and specific discharge vary considerably even in neighboring and rather similar catchments under current climate conditions and that these variations are related to landscape characteristics. Therefore we hypothesize that these landscape characteristics also play a fundamental role for the sensitivity of a catchment to changing climate conditions. We analyzed the hydrological response of 14 partially nested catchments in Northern Sweden with slightly different topography, land cover, size and geology. Current (1981-2010) and future (2061-2090) streamflows were simulated with the hydrological model HBV light based on 15 regional climate model projections that were bias-corrected with a distribution-mapping approach. Our simulations revealed that - in a future climate- the total annual streamflow will be higher, spring flood peaks will occur earlier and decrease considerably, whereas winter base flows will more than double. These changes are somewhat expected and mainly triggered by a projected increase in winter temperature, which leads to less snow accumulation on the ground. However, our results also show that there is a large variability amongst these catchments in their hydrological response to the same future climate conditions. We identified wetlands, lakes, peat soils and higher elevations as factors that had a stronger effect on spring floods, whereas catchments dominated by forests, steeper slopes and till soils showed stronger responses in winter base flows and total annual streamflow. Therefore, our results suggest that the sensitivity of catchments to future climate conditions is strongly linked to landscape characteristics and also depends on the streamflow characteristic as well as season analyzed.

  6. The examination of climate comfortable conditions in terms of coastal tourism on the Aegean Region coastal belt

    Directory of Open Access Journals (Sweden)

    Yüksel Güçlü

    2010-03-01

    Full Text Available It is important that climate comfortable conditions are within presumed threshold values with respect to tourism activities in the form that people rest in a healthy environment. The climatical elements bearing importance for climate comfortable conditions in general sunshine duration, temperature, relative humidity, wind and precipitation have been taken into consideration for this purpose. The purpose of this study is to examine of the climate comfortable conditions in respect to tourism on the Aegean Region coastal belt of Turkey. In this study, TCI, THI and SSI indices have been used for determining climate comfort conditions. The best climate comfortable conditions in terms of coastal tourism are seen May-June and September-October periods in the study area. Climate comfortable decreases due to high temperature and relative humidity in July-August period. November-April period is not appropriate for the coastal tourism. The favourable period for sea bathing is seen between 9 June-26 September.

  7. Sensitivity of Pliocene climate simulations in MRI-CGCM2.3 to respective boundary conditions

    Science.gov (United States)

    Kamae, Youichi; Yoshida, Kohei; Ueda, Hiroaki

    2016-08-01

    Accumulations of global proxy data are essential steps for improving reliability of climate model simulations for the Pliocene warming climate. In the Pliocene Model Intercomparison Project phase 2 (PlioMIP2), a part project of the Paleoclimate Modelling Intercomparison Project phase 4, boundary forcing data have been updated from the PlioMIP phase 1 due to recent advances in understanding of oceanic, terrestrial and cryospheric aspects of the Pliocene palaeoenvironment. In this study, sensitivities of Pliocene climate simulations to the newly archived boundary conditions are evaluated by a set of simulations using an atmosphere-ocean coupled general circulation model, MRI-CGCM2.3. The simulated Pliocene climate is warmer than pre-industrial conditions for 2.4 °C in global mean, corresponding to 0.6 °C warmer than the PlioMIP1 simulation by the identical climate model. Revised orography, lakes, and shrunk ice sheets compared with the PlioMIP1 lead to local and remote influences including snow and sea ice albedo feedback, and poleward heat transport due to the atmosphere and ocean that result in additional warming over middle and high latitudes. The amplified higher-latitude warming is supported qualitatively by the proxy evidences, but is still underestimated quantitatively. Physical processes responsible for the global and regional climate changes should be further addressed in future studies under systematic intermodel and data-model comparison frameworks.

  8. Performance Based Evaluation of Concrete Strength under Various Curing Conditions to Investigate Climate Change Effects

    Directory of Open Access Journals (Sweden)

    Tae-Kyun Kim

    2015-07-01

    Full Text Available Recently, the manifestation of global warming-induced climate change has been observed through super typhoons, heavy snowfalls, torrential rains, and extended heat waves. These climate changes have been occurring all over the world and natural disasters have caused severe damage and deterioration of concrete structures and infrastructure. In an effort to deal with these problems due to extreme and abnormal climate changes, studies have been conducted to develop construction technologies and design guidelines. Nevertheless, study results applicable to construction sites continue to be ineffective and insufficient. Therefore, this study proposes ways to cope with climate change by considering the effect of concrete curing condition variations on concrete material performance. More specifically, the 3-, 7- and 28-day compressive and split tensile strength properties of concrete mix cured under various climatic factors including temperature, relative humidity, wind speed, and sunlight exposure time were evaluated to determine whether the concrete meets the current design requirements. Thereafter, a performance based evaluation (PBE was performed using satisfaction probabilities based on the test values to understand the problems associated with the current mix proportion design practice and to identify countermeasures to deal with climate change-induced curing conditions.

  9. Conditions for Emergence, Stability and Change in New Organizations in the Field of Citizens Climate Action

    DEFF Research Database (Denmark)

    Figueroa, Maria Josefina

    Climate change represents a crisis of tangible measure and the emergence of a field of action within which acting today needs to be motivated for what can contribute to benefit climate and transform society into a low carbon tomorrow. With the breadth and scope of citizen action on climate change...... expanding worldwide the weight of expectations can be boiled down to two: One refers to their potential for delivering specific mitigation/adaptation goals; the second refers to their organizational potential, stability and the manner in which they can ultimately affect societal transformational change....... This contribution is concerned with the latter. It proposes that using field analysis it is possible to understand conditions of emergence, stability and change in citizen engagement in climate action. The present contribution offers only a preliminary exploration of possibilities for how using field...

  10. Hydrological Modeling in Northern Tunisia with Regional Climate Model Outputs: Performance Evaluation and Bias-Correction in Present Climate Conditions

    Directory of Open Access Journals (Sweden)

    Asma Foughali

    2015-07-01

    Full Text Available This work aims to evaluate the performance of a hydrological balance model in a watershed located in northern Tunisia (wadi Sejnane, 378 km2 in present climate conditions using input variables provided by four regional climate models. A modified version (MBBH of the lumped and single layer surface model BBH (Bucket with Bottom Hole model, in which pedo-transfer parameters estimated using watershed physiographic characteristics are introduced is adopted to simulate the water balance components. Only two parameters representing respectively the water retention capacity of the soil and the vegetation resistance to evapotranspiration are calibrated using rainfall-runoff data. The evaluation criterions for the MBBH model calibration are: relative bias, mean square error and the ratio of mean actual evapotranspiration to mean potential evapotranspiration. Daily air temperature, rainfall and runoff observations are available from 1960 to 1984. The period 1960–1971 is selected for calibration while the period 1972–1984 is chosen for validation. Air temperature and precipitation series are provided by four regional climate models (DMI, ARP, SMH and ICT from the European program ENSEMBLES, forced by two global climate models (GCM: ECHAM and ARPEGE. The regional climate model outputs (precipitation and air temperature are compared to the observations in terms of statistical distribution. The analysis was performed at the seasonal scale for precipitation. We found out that RCM precipitation must be corrected before being introduced as MBBH inputs. Thus, a non-parametric quantile-quantile bias correction method together with a dry day correction is employed. Finally, simulated runoff generated using corrected precipitation from the regional climate model SMH is found the most acceptable by comparison with runoff simulated using observed precipitation data, to reproduce the temporal variability of mean monthly runoff. The SMH model is the most accurate to

  11. 未来气候情景下西藏地区的干湿状况变化趋势%Trends Of Tibet's Dry-Wet Condition under Future Climate Scenario

    Institute of Scientific and Technical Information of China (English)

    赵俊芳; 郭建平; 房世波; 毛飞

    2011-01-01

    The drought is one of the important meteorological disasters in Tibet, and occurs in varying degrees each year. The drought has a great impact on the agriculture and livestock production. It has an important significance that forecasting the trends of Tibet's dry-wet condition under future climate scenario for prevention and reduction of losses caused by drought in the region. Based on the daily data of A2 climate scenario (2011 -2050) and baseline climate condition (1961 -1990) from the regional climate model PRECIS with resolution of 50km × 50km, reference crop evapotranspiration was calculated according to Penman-Monteith equation recommended by FAO. In terms of grades of wetness index from Chinese Climate Classification Criterion, Tibet is classified into arid, semi-arid, semi-humid and humid zones, respectively. The possible temporal-spatial changes of dry-wet condition in Tibet from 2011 to 2050 were analyzed based on wetness index. The results showed that: the amount of precipitation and reference crop evapotranspiration in the most regions of Tibet would increase from 2011 to 2050 compared with the baseline climate conditions from 1961 to 1990. The increase range of reference crop evapotranspiration was less than that of precipitation. However, the inter-regional differences were both significant; in the next 40 years, Tibet's climate showed a warming and wetting trend in general. The reducing trends in arid and semi-arid areas were clear. And the increase range of average temperature was far greater than that of wetness index. Environmental water and heat factors were higher and drought gradually decreased. It was more conducive to the improvement of ecological environment; however, the different climatic zones in dry-wet conditions at different times showed different trends. The area's reducing trend in the arid and semiarid region and the expanding trend in the humid and semi-humid region during 2021 to 2030 would be obvious compared with the

  12. Environmental Risk of Climate Change and Groundwater Abstraction on Ecological Conditions in a Danish Catchment

    Science.gov (United States)

    Seaby, L. P.; Boegh, E.; Jensen, N. H.

    2014-12-01

    The Danish drinking water supply is sourced almost entirely from groundwater. Balancing water abstraction demands and the ecological conditions in streams is one of the major challenges for water resource managers. With projected climate change, characterised by increased annual temperature, precipitation, and evapotranspiration rates for Denmark, the impact to low flows and groundwater levels are especially of interest, as they relate to aquatic habitat and nitrate leaching, respectively. On the island Sjælland, which includes urban and agricultural regions, a doubling of groundwater abstraction rates has been proposed in selected areas to meet water resource demands. This study evaluates the risk to stream ecological conditions for a lowland Danish catchment under multiple scenarios of climate change and groundwater abstraction. Projections of future climate (i.e. precipitation, temperature, reference evapotranspiration) come from the ENSEMBLES climate modelling project. Climate variables from 11 climate models are first bias corrected with a distribution based scaling (DBS) method (Seaby et al., 2013) and then used to force hydrological simulations of stream discharge, groundwater recharge, and nitrate leaching from the root zone under present (1991-2010) and future (2071-2100) climate conditions. Hydrological modelling utilises a sequential coupling methodology with DAISY, a one dimensional crop model describing soil water dynamics in the root zone, and MIKE SHE, a distributed groundwater-surface water model which the National Water Resources Model (DK-model) is set up in (Henriksen et al., 2003). We find low flow and annual discharge to be most impacted by scenarios of climate change, with high variation across climate models (+/- 40% change). Doubling of current groundwater abstraction rates reduces annual discharge by approximately 20%, with higher reductions to low flows seen around 40%. The combined effects of climate change and increased groundwater

  13. Relation of ice conditions to climate change in the Bohai Sea of China

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The ice conditions in the Bohai Sea and the northern Huanghai Sea greatly change from year to year with winter climate. Ice only covers below 15% of the the waters during the warmest win ter, while it covers more than 80% during the coldest winter. Ice observation and data acquisition are outlined in the paper. The ice-covered area, the position of ice edge and the ice grades give indication of the ice conditions. The local climate of the waters can be expressed by using the air temperature of the stations of Dalian and Yingkou. The variation of the ice condition indexes with the monthly mean air temperature at Dalian from 1952 to 2000 is shown, as well. The local climate and ice conditions in the waters are affected by many factors, such as, evolution of the general atmospheric circulation and the solar activity. The delayed correlation between the ice conditions and lots of the affecting factors is analysed in the paper. The ice conditions are continuously mild since the 1990s, that is relative to the tendency of the global warming. The ice condition variation of the Bohai Sea is related to the El Nino event and the sunspot period. The seasonal evolution of the ice conditions is also described in the paper.

  14. Effects of Phosphorus Application in Different Soil Layers on Root Growth, Yield, and Water-Use Efifciency of Winter Wheat Grown Under Semi-Arid Conditions

    Institute of Scientific and Technical Information of China (English)

    KANG Li-yun; YUE Shan-chao; LI Shi-qing

    2014-01-01

    Deep phosphorus application can be a usefull measure to improve crops’ performance in semi-arid regions, but more knowledge of both its general effects and effects on speciifc crops is required to optimize treatments. Thus, the aims of this study were to evaluate the effects of phosphorus (P) application at different soil layers on root growth, grain yield, and water-use efifciency (WUE) of winter wheat grown on the semi-arid Loess Plateau of China and to explore the relationship between root distribution and grain yield. The experiment consisted of four P treatments in a randomized complete block design with three replicates and two cultivars: one drought-sensitive (Xiaoyan 22, XY22) and one drought-tolerant (Changhan 58, CH58). The four P treatments were no P (control, CK), surface P (SP), deep P (DP), and deep-band P application (DBP). CH58 produced larger and deeper root systems, and had higher grain yields and WUE, under the deep P treatments (DP and DBP) than under SP, clearly showing that deep P placement had beneifcial effects on the drought-tolerant cultivar. In contrast, the grain yield and root growth of XY22 did not differ between DP or DBP and SP treatments. Further, root dry weight (RW) and root length (RL) in deep soil layer (30-100 cm) were closely positively correlated with grain yield and WUE of CH58 (but not XY22), highlighting the connections between a well-developed subsoil root system and both high grain yield and WUE for the drought-tolerant cultivar. WUE correlated strongly with grain yield for both cultivars (r=0.94,P<0.001). In conclusion, deep application of P fertilizer is a practical and feasible means of increasing grain yield and WUE of rainfed winter wheat in semi-arid regions, by promoting deep root development of drought-tolerant cultivars.

  15. Assessment of production risks for winter wheat in different German regions under climate change conditions

    Science.gov (United States)

    Kersebaum, K. C.; Gandorfer, M.; Wegehenkel, M.

    2012-04-01

    The study shows climate change impacts on wheat production in selected regions across Germany. To estimate yield and economic effects the agro-ecosystem model HERMES was used. The model performed runs using 2 different releases of the model WETTREG providing statistically downscaled climate change scenarios for the weather station network of the German Weather Service. Simulations were done using intersected GIS information on soil types and land use identifying the most relevant sites for wheat production. The production risks for wheat yields at the middle of this century were compared to a reference of the present climate. The irrigation demand was determined by the model using an automatic irrigation mode. Production risks with and without irrigation were assessed and the economic feasibility to reduce production risks by irrigation was evaluated. Costs and benefits were compared. Additionally, environmental effects, e.g. groundwater recharge and nitrogen emissions were assessed for irrigated and rain fed systems. Results show that positive and negative effects of climate change occur within most regions depending on the site conditions. Water holding capacity and groundwater distance were the most important factors which determined the vulnerability of sites. Under climate change condition in the middle of the next century we can expect especially at sites with low water holding capacity decreasing average gross margins, higher production risks and a reduced nitrogen use efficiency under rainfed conditions. Irrigation seems to be profitable and risk reducing at those sites, provided that water for irrigation is available. Additionally, the use of irrigation can also increase nitrogen use efficiency which reduced emissions by leaching. Despite the site conditions results depend strongly on the used regional climate scenario and the model approach to consider the effect of elevated CO2 in the atmosphere.

  16. Identifying Groundwater Recharge in Arid Regions

    Science.gov (United States)

    Thomas, B. F.; Famiglietti, J. S.

    2015-12-01

    Recharge epodicity in arid regions provides a method to estimate annual groundwater recharge given a relationship expressed as the recharge to precipitation ratio. Traditionally, in-situ observations are required to identify aquifer recharge events, while more advanced approaches such as the water-table fluctuation method or the episodic master recession method are necessary to delineate the recharge event. Our study uses the Gravity Recovery and Climate Experiment (GRACE) observations to estimate monthly changes in groundwater storage which are attributed to the combination of groundwater abstraction and episodic recharge in the arid southwestern United States. Our results illustrate the ability of remote sensing technologies to identify episodic groundwater recharge in arid regions which can be used within sustainable groundwater management frameworks to effectively manage groundwater resources.

  17. Assessment of monitored energy use and thermal comfort conditions in mosques in hot-humid climates

    Energy Technology Data Exchange (ETDEWEB)

    Al-Homoud, Mohammad S.; Abdou, Adel A.; Budaiwi, Ismail M. [Architectural Engineering Department, KFUPM, Dhahran 31261 (Saudi Arabia)

    2009-06-15

    In harsh climatic regions, buildings require air-conditioning in order to provide an acceptable level of thermal comfort. In many situations buildings are over cooled or the HVAC system is kept running for a much longer time than needed. In some other situations thermal comfort is not achieved due to improper operation practices coupled with poor maintenance and even lack it, and consequently inefficient air-conditioning systems. Mosques represent one type of building that is characterized by their unique intermittent operating schedule determined by prayer times, which vary continuously according to the local solar time. This paper presents the results of a study designed to monitor energy use and thermal comfort conditions of a number of mosques in a hot-humid climate so that both energy efficiency and the quality of thermal comfort conditions especially during occupancy periods in such intermittently operated buildings can be assessed accurately. (author)

  18. Evapotranspiration estimate in the Mediterranean: the comparison between different methods and possible impacts of climate change

    Science.gov (United States)

    Todorovic, Mladen; Karic, Biljana; Santos Pereira, Luis; Lionello, Piero

    2015-04-01

    This work focused on the performances of different methods to estimate evapotranspiration (ET) across the Mediterranean climates. Two types of monthly weather data were used in the analysis: CLIMWAT historical database for 577 meteorological stations located in the Mediterranean countries and data derived from the ENSEMBLES project (EC-FP6-ENV) Regional Circulation Model (RCM) simulations. The performance of two temperature based approaches for the estimation of reference evapotranspiration (Hargreaves-Samani - HS and the FAO Penman-Monteith with temperature data only - PMT) was assessed against the Penman-Monteith approach (PM) using a full input climate data. Data were grouped according to climate: hyper-arid, arid, semi-arid, dry sub-humid, moist sub-humid and humid zones. For almost all zones, the statistical parameters indicate slightly better performance of PMT than HS method. Both methods tend to underestimate ETo in hyper arid areas and to overestimate ETo in humid areas. The reduction of either minimum air temperature or dew temperature by 2°C under arid conditions (when the ratio between precipitation and ETo is smaller than 0.4) improves ETo estimation especially for interior locations and in hyper-arid and arid regions. The analysis performed for the future referred to the A1B SRES scenario for the period 2036-2065 using the results of RACMO2 driven by ECHAM5. The overall results indicated the redistribution of climatic zone over the Mediterranean with the further extension of arid zones towards higher altitudes. Accordingly, the variation in the performances of ET models was observed. Moreover, the climate change had an impact of the peak monthly evapotranspiration of Mediterranean crops which, in turn, affected the climatic water balance over the whole region.

  19. Collaborative Research. Quantifying Climate Feedbacks of the Terrestrial Biosphere under Thawing Permafrost Conditions in the Arctic

    Energy Technology Data Exchange (ETDEWEB)

    Zhuang, Qianlai [Purdue Univ., West Lafayette, IN (United States); Schlosser, Courtney [Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States); Melillo, Jerry [Marine Biological Lab. (MBL), Woods Hole, MA (United States); Walter, Katey [Univ. of Alaska, Fairbanks, AK (United States)

    2015-09-15

    Our overall goal is to quantify the potential for threshold changes in natural emission rates of trace gases, particularly methane and carbon dioxide, from pan-arctic terrestrial systems under the spectrum of anthropogenically-forced climate warming, and the conditions under which these emissions provide a strong feedback mechanism to global climate warming. This goal is motivated under the premise that polar amplification of global climate warming will induce widespread thaw and degradation of the permafrost, and would thus cause substantial changes to the landscape of wetlands and lakes, especially thermokarst (thaw) lakes, across the Arctic. Through a suite of numerical experiments that encapsulate the fundamental processes governing methane emissions and carbon exchanges – as well as their coupling to the global climate system - we intend to test the following hypothesis in the proposed research: There exists a climate warming threshold beyond which permafrost degradation becomes widespread and stimulates large increases in methane emissions (via thermokarst lakes and poorly-drained wetland areas upon thawing permafrost along with microbial metabolic responses to higher temperatures) and increases in carbon dioxide emissions from well-drained areas. Besides changes in biogeochemistry, this threshold will also influence global energy dynamics through effects on surface albedo, evapotranspiration and water vapor. These changes would outweigh any increased uptake of carbon (e.g. from peatlands and higher plant photosynthesis) and would result in a strong, positive feedback to global climate warming.

  20. Crash testing hydrological models in contrasted climate conditions: An experiment on 216 Australian catchments

    Science.gov (United States)

    Coron, L.; AndréAssian, V.; Perrin, C.; Lerat, J.; Vaze, J.; Bourqui, M.; Hendrickx, F.

    2012-05-01

    This paper investigates the actual extrapolation capacity of three hydrological models in differing climate conditions. We propose a general testing framework, in which we perform series of split-sample tests, testing all possible combinations of calibration-validation periods using a 10 year sliding window. This methodology, which we have called the generalized split-sample test (GSST), provides insights into the model's transposability over time under various climatic conditions. The three conceptual rainfall-runoff models yielded similar results over a set of 216 catchments in southeast Australia. First, we assessed the model's efficiency in validation using a criterion combining the root-mean-square error and bias. A relation was found between this efficiency and the changes in mean rainfall (P) but not with changes in mean potential evapotranspiration (PE) or air temperature (T). Second, we focused on average runoff volumes and found that simulation biases are greatly affected by changes in P. Calibration over a wetter (drier) climate than the validation climate leads to an overestimation (underestimation) of the mean simulated runoff. We observed different magnitudes of these models deficiencies depending on the catchment considered. Results indicate that the transfer of model parameters in time may introduce a significant level of errors in simulations, meaning increased uncertainty in the various practical applications of these models (flow simulation, forecasting, design, reservoir management, climate change impact assessments, etc.). Testing model robustness with respect to this issue should help better quantify these uncertainties.

  1. Humpback whale diets respond to variance in ocean climate and ecosystem conditions in the California Current.

    Science.gov (United States)

    Fleming, Alyson H; Clark, Casey T; Calambokidis, John; Barlow, Jay

    2016-03-01

    Large, migratory predators are often cited as sentinel species for ecosystem processes and climate-related changes, but their utility as indicators is dependent upon an understanding of their response to environmental variability. Documentation of the links between climate variability, ecosystem change and predator dynamics is absent for most top predators. Identifying species that may be useful indicators and elucidating these mechanistic links provides insight into current ecological dynamics and may inform predictions of future ecosystem responses to climatic change. We examine humpback whale response to environmental variability through stable isotope analysis of diet over a dynamic 20-year period (1993-2012) in the California Current System (CCS). Humpback whale diets captured two major shifts in oceanographic and ecological conditions in the CCS. Isotopic signatures reflect a diet dominated by krill during periods characterized by positive phases of the North Pacific Gyre Oscillation (NPGO), cool sea surface temperature (SST), strong upwelling and high krill biomass. In contrast, humpback whale diets are dominated by schooling fish when the NPGO is negative, SST is warmer, seasonal upwelling is delayed and anchovy and sardine populations display increased biomass and range expansion. These findings demonstrate that humpback whales trophically respond to ecosystem shifts, and as a result, their foraging behavior is a synoptic indicator of oceanographic and ecological conditions across the CCS. Multi-decadal examination of these sentinel species thus provides insight into biological consequences of interannual climate fluctuations, fundamental to advancing ecosystem predictions related to global climate change. PMID:26599719

  2. Soil carbon in the arid and semi-arid tropics

    International Nuclear Information System (INIS)

    Soils in the arid and semi-arid tropics are often poor in soil organic matter (SOM) contents. On the other hand, calcretes and soils with calcic or petrocalcic horizons have a world-wide distribution and are regarded as important carbon reservoirs. For this reason, knowledge on their formation processes and the carbon source-sink relationship is necessary. An evaluation is made of the major models of calcrete formation using stable isotope techniques, especially on Tunisian soils. Normally, calcretes do not act as carbon sinks unless at least part of the calcium originates from weathering. However, in some cases they can change to carbon sources under anthropogenically altered environmental conditions when acids are precipitated. Desert losses are quite rich in carbonates and can form fertile soils, but good management practices and conservation efforts are required. These soils are usually poor in SOM contents and their carbon source-sink relationship depends on the way in which the soil is managed. Vertisols play an important role in soils of the semi-arid tropics. Despite their dark colour, they generally contain little organic carbon. Using stable isotope and radiocarbon methods it has been shown that carbon fixation takes place even over a few decades. Research experiments carried out on Vertisols in India have shown that the SOM decomposition rates can be influenced by the soil management practices. (author). 3 figs

  3. The uncertainty cascade in flood risk assessment under changing climatic conditions - the Biala Tarnowska case study

    Science.gov (United States)

    Doroszkiewicz, Joanna; Romanowicz, Renata

    2016-04-01

    Uncertainty in the results of the hydraulic model is not only associated with the limitations of that model and the shortcomings of data. An important factor that has a major impact on the uncertainty of the flood risk assessment in a changing climate conditions is associated with the uncertainty of future climate scenarios (IPCC WG I, 2013). Future climate projections provided by global climate models are used to generate future runoff required as an input to hydraulic models applied in the derivation of flood risk maps. Biala Tarnowska catchment, situated in southern Poland is used as a case study. Future discharges at the input to a hydraulic model are obtained using the HBV model and climate projections obtained from the EUROCORDEX project. The study describes a cascade of uncertainty related to different stages of the process of derivation of flood risk maps under changing climate conditions. In this context it takes into account the uncertainty of future climate projections, an uncertainty of flow routing model, the propagation of that uncertainty through the hydraulic model, and finally, the uncertainty related to the derivation of flood risk maps. One of the aims of this study is an assessment of a relative impact of different sources of uncertainty on the uncertainty of flood risk maps. Due to the complexity of the process, an assessment of total uncertainty of maps of inundation probability might be very computer time consuming. As a way forward we present an application of a hydraulic model simulator based on a nonlinear transfer function model for the chosen locations along the river reach. The transfer function model parameters are estimated based on the simulations of the hydraulic model at each of the model cross-section. The study shows that the application of the simulator substantially reduces the computer requirements related to the derivation of flood risk maps under future climatic conditions. Acknowledgements: This work was supported by the

  4. Effect of climate factors on wood veneers exposed to outdoor conditions in black sea region

    OpenAIRE

    Köse, Gaye; Temiz, Ali; Akbaş, Selçuk; Özkan, Emre

    2013-01-01

    In this study, 2×100×200 mm wood veneers obtained from Scots pine (Pinus sylvestris L.), European black pine (Pinus nigra Arn.) and beech (Fagus orientalis L.) wood were exposed to outdoor climate conditions at three different cities (Trabzon, Artvin, and Kastamonu) of Black Sea region in Turkey for totally 4 months from May to August, 2012. The aim of this study was to investigate the effect of climate factors on the changes occurred on different types of wood veneers that were subjected to ...

  5. How does forest thinning affect short- and long-term water partitioning in the semi-arid Santa Fe Municipal Watershed, and how do these changes compare to unmediated forest responses to climate change?

    Science.gov (United States)

    Dugger, A. L.; Tague, C.; Allen, C. D.; Ringler, T.

    2011-12-01

    In water-limited environments, water and vegetation systems are intrinsically linked. Vegetation exerts direct controls on water partitioning through transpiration and indirect controls on partitioning through radiation and precipitation interception, rooting effects on soil permeability, and litter effects on water capture and storage, among others. In semi-arid forest systems of the Southwest U.S. in particular, vegetation controls on water partitioning are often the most dominant after climate, so changes in vegetation structure, species type, and biomass can lead to large shifts in downstream water availability. We use a coupled ecologic-hydrologic, process-based model (RHESSys) to investigate how human- and nature-induced changes in vegetation biomass, structure, and spatial distribution affect the partitioning of water into evaporation (E), transpiration (T), groundwater recharge (GW), and streamflow (Q) in the Santa Fe Municipal Watershed in Northern New Mexico. Previous work at this site has shown that RHESSys can successfully capture observed seasonal streamflow patterns and inter-annual biomass dynamics (growth/mortality) in response to climate. In this study, we use sensitivity analysis of model vegetation parameterization to estimate the relative magnitude of responses in E, T, GW, and Q due to a range of different vegetation manipulation scenarios, including uniform changes in biomass, varying spatial patterns of vegetation thinning, increasing canopy cover gaps through thinning, and changes in litter and coarse woody debris. The dynamic vegetation model allows us to not only evaluate instantaneous changes in partitioning associated with these manipulations, but also how partitioning evolves over time. Finally, we compare model estimates of effects on water partitioning from forest treatment to effects from unmediated "natural" vegetation responses to climate warming.

  6. Effect of climatic conditions on the development of soil water repellency in soils treated with the wastewater of the olive oil production

    Science.gov (United States)

    Schaumann, Gabriele E.; Peikert, Benjamin; Tamimi, Nesreen; Steinmetz, Zacharias; Fischer, Jonas; Bibus, Daniel; Marei Sawalha, Amer; Dag, Arnon

    2014-05-01

    The disposal of untreated wastewater on soil can induce severe water repellency. The final degree of water repellency may strongly depend on the environmental conditions prevailing during and after disposal. Also unpolluted soil can develop severe water repellency upon exposure to extreme heat or draught events. The induced water repellency can be either persistent or of transient nature. However, the underlying mechanisms are not yet completely understood. The objective of this study was to investigate how climatic conditions determine the development and persistence of water repellency following wastewater disposal. Our hypothesis was that amphiphilic organic wastewater compounds physically sorb onto surfaces, which renders them hydrophobic. Depending on temperature and moisture, those compounds are degraded, chemically incorporated into SOM, or irreversibly sorbed to soil particles during the time after the first waste water-soil contact. According to our hypothesis, biological communities favor degradation and transformation of OM of waste water into SOM under moist soil conditions. This would reduce the initial hydrophobization. In contrast, drying irreversibly renders soil hydrophobic and phytotoxic due to immobilization of OMW OM in the soil. To test these hypotheses, we investigated effects of olive mil wastewater (OMW), the effluent originating from olive oil production, directly applied to soil. In Israel and Palastine, olive oil production generates large amounts of OMW within a short period of time between November and January. As sewage facilities do not accept OMW, it is often disposed onto soil, which leads to severe soil and groundwater pollution. If the above mentioned hypotheses match, pollution and hydrophobization might be minimized if the wastewater is discharged at the right time of the year. In order to test this, we conducted field (2-3 years) and laboratory (60 days) experiments in Israel (Gilat, arid climate) and in the West Bank (Bait

  7. An integrated assessment of the impact of precipitation and groundwater on vegetation growth in arid and semiarid areas

    OpenAIRE

    Zhu, Lin; Gong, Huili; Dai, Zhenxue; Xu, Tingbao; Su, Xiaosi

    2014-01-01

    Increased demand for water resources together with the influence of climate change has degraded water conditions which support vegetation in many parts of the world, especially in arid and semiarid areas. This study develops an integrated framework to assess the impact of precipitation and groundwater on vegetation growth in the Xiliao River Plain of northern China. The integrated framework systematically combines remote sensing technology with water flow modeling in the vadose zone and field...

  8. Projections of climate conditions that increase coral disease susceptibility and pathogen abundance and virulence

    Science.gov (United States)

    Maynard, Jeffrey; van Hooidonk, Ruben; Eakin, C. Mark; Puotinen, Marjetta; Garren, Melissa; Williams, Gareth; Heron, Scott F.; Lamb, Joleah; Weil, Ernesto; Willis, Bette; Harvell, C. Drew

    2015-07-01

    Rising sea temperatures are likely to increase the frequency of disease outbreaks affecting reef-building corals through impacts on coral hosts and pathogens. We present and compare climate model projections of temperature conditions that will increase coral susceptibility to disease, pathogen abundance and pathogen virulence. Both moderate (RCP 4.5) and fossil fuel aggressive (RCP 8.5) emissions scenarios are examined. We also compare projections for the onset of disease-conducive conditions and severe annual coral bleaching, and produce a disease risk summary that combines climate stress with stress caused by local human activities. There is great spatial variation in the projections, both among and within the major ocean basins, in conditions favouring disease development. Our results indicate that disease is as likely to cause coral mortality as bleaching in the coming decades. These projections identify priority locations to reduce stress caused by local human activities and test management interventions to reduce disease impacts.

  9. Impacts of Autonomous Adaptations on the Hydrological Drought Under Climate Change Condition

    Science.gov (United States)

    Oki, T.; Satoh, Y.; Pokhrel, Y. N.; KIM, H.; Yoshimura, K.

    2014-12-01

    Because of expected effects of climate changes on quantity and spatial distribution of available water resources, assessment of the changes in the balance between the demand and supply of water resources is critical for some regions. Historically, water deficiencies were overcome by planned water management such as dam regulation and irrigation. But only few studies have investigated the effect of anthropogenic factors on the risk of imbalance of water demand and supply under climate change conditions. Therefore, estimation of the potential deficiency in existing infrastructures under water-environment change is needed to support our society to adapt against future climate changes. This study aims to estimate the impacts of climate changes on the risk of water scarcity projected based on CMIP5 RCP scenarios and the efficiency of autonomous adaptation by anthropogenic water management, such as reservoir operation and irrigation using ground water. First, tendencies of the changes in water scarcity under climate change are estimated by an improved land surface model, which integrates natural water cycles and human activities. Second, the efficiencies of human-developed infrastructure are analyzed by comparing the naturalized and fully anthropogenic offline simulations. It was found that number of hydrological drought days will be increased and decreased in approximately 70 % and 24 % of global land, respectively, considering anthropogenic water management, however, they are approximately 82 % and 16 %, respectively, under naturalized condition without anthropogenic water management. The differences indicate how autonomous adaptation through anthropogenic water management can reduce the impacts of climate change. Also, adequate enhancement of infrastructure is necessary against expected water scarcity under climate change because such positive and negative effects of artificial water regulation show comparable impact on water scarcity risk to that of climate change in

  10. Land use water level fluctuation and water quality in two reservoirs subjected to semi-arid climate (Trás-os-Montes, Portugal)

    OpenAIRE

    Geraldes, Ana Maria; Maria José BOAVIDA

    2002-01-01

    Serra Serrada and Azibo reservoirs are located in River Douro watershed. The cLimate is continental, with warm, dry summers and long, cold winters. Precipitation occurs mainly in Autumn and Winter, although in a very irregular regime with wet winters to followed by drought ones.

  11. Water supply patterns in two agricultural areas of Central Germany under climate change conditions

    Directory of Open Access Journals (Sweden)

    M. H. Tölle

    2012-04-01

    Full Text Available Increasing emissions of greenhouse gases and increasing prices for fossil fuels have highlighted the demand for CO2 "neutral" renewable energy sources, e.g. short rotation forestry systems used for bioenergy. These systems might be vulnerable to changes in temperature, precipitation and occurrence of extreme weather events. To estimate success or failure of such short rotation coppices in a certain area we need regional climate projections and risk assessment. Changes of water supply patterns in two agriculturally extensively used regions in Central Germany (around Göttingen and Großfahner with different climate conditions but both in the temperate climate zone are explored. The study is carried out under present conditions as well as under projected climate change conditions (1971–2100 using A1B and B1 climate scenarios downscaled for Europe. Analysis of precipitation bias shows regional differences: a strong bias in Göttingen area and a weaker bias in the Großfahner area. A bias correction approach, Quantile mapping, is applied to the ensemble results for both areas for winter and summer seasons. By using quantile regression on the seasonal Standardized Precipitation Indices (SPIs as indicator for water supply conditions we found that precipitation is expected to increase in winter in all quantiles of the distribution for Göttingen area during the 21th century. Heavy precipitation is also expected to increase for Großfahner area suggesting a trend to wetter extremes in winter for the future. This winter precipitation increase could trigger runoff and soil erosion risk enhancing the severity of floods. Increasing winter availability of water could enhance local water supply in spring. For both areas no significant change in summer was found over the whole time period. Although the climate change signal of the SPI indicate mild dryer conditions in summer at the end of the 21st century which may trigger water shortage and

  12. Hydro-climatic conditions and thermoelectric electricity generation – Part I: Development of models

    International Nuclear Information System (INIS)

    In recent years there have been several heat waves affecting the use of thermoelectric power plants, e.g. in Europe and the U.S. In this paper the linkage between hydro-climatic conditions and possible electricity generation restrictions is described. The coupling of hydrological models and a power plant model is presented. In this approach each power plant is considered separately with its technical specifications. Also environmental regulations, e.g. permissible rise in the cooling water temperature, are considered for the respective power plant. The hydrological models developed to simulate river runoff and water temperature are also site specific. The approach presented is applied to Krümmel nuclear power plant in Germany. Analysed are the uncertainties with regard to electricity generation restrictions on account of climatic developments and corresponding higher water temperatures and low flows. Overall, increased water temperatures and declining river runoff lead to more frequent and more severe generation restrictions. It is concluded that the site-specific approach is necessary to reliably simulate power plants water demand, river runoff and water temperature. Using a simulation time step of one day, electricity generation restrictions are significantly higher than for simulations at monthly time step. - Highlights: • An approach to assess climate effects on electricity generation is presented. • Site specific models for power plants, water temperature and discharge are used. • Monthly and daily simulation time-steps give different results. • Climate change effects on generation depend on cooling system and climate scenario

  13. Sensitivity of ICTP Regional Climate Model (RegCM3) to Initial and Lateral Boundary Conditions

    Science.gov (United States)

    Nadeem, I.; Formayer, H.

    2009-04-01

    Regional climate simulations require lateral boundary conditions. These are typically reanalysis of past observations or alternatively, output from climate general circulation models. Lateral boundary conditions are available at various temporal and spatial resolutions. At present, spatial resolution of reanalysis datasets ranges from few kilometers, for example, regional reanalysis limited to only single continent, to the coarser but global datasets like ECMWF 40 Years Re-Analysis. While these datasets represent reasonable analyses of 3-D atmospheric as well as surface conditions, their resolutions, the physics of the models used to generate them, and the means of assimilating data into them can produce very different results when used as boundary conditions for regional climate models. The sensitivity of ICTP Regional Climate Model (RegCM3) to different lateral boundary conditions was investigated over the Alpine region. The model was run directly at 10km horizontal resolution as well as in one-way double nested mode, with a 30 km grid point spacing mother domain encompassing the Europe and a 10 km grid point spacing nested domain covering the Alpine Region. The simulations spans the one-year period of 1989. The boundary conditions used for various simulations were ECMWF Interim Re-Analysis (ERA-Interim, 0.75° and 1.5° grid spacings, 6-h intervals), the ECMWF 40 Years Re-Analysis (ERA40, 1° and 2.5° grid spacings, 6-h interval) and finally the 2.5°, 6-h NCEP/DOE AMIP-II Reanalysis (Reanalysis-2). Sea Surface Temperature for the simulated periods were obtained from a UK Met Office Global Ocean Surface Temperature (GISST), a set of SST data in monthly 1° area grids. When recently released ERA-Interim Reanalysis, which is based on a recent release of the Integrated Forecasting System (IFS Cy31r2) containing many improvements both in the forecasting model and analysis methodology, was used as lateral and boundary conditions, the simulated precipitation field

  14. Groundwater flow modelling of periods with periglacial and glacial climate conditions - Laxemar

    Energy Technology Data Exchange (ETDEWEB)

    Vidstrand, Patrik (TerraSolve AB, Floda (Sweden)); Rhen, Ingvar (SWECO Environment AB, Falun (Sweden)); Zugec, Nada (Bergab, Goeteborg (Sweden))

    2010-12-15

    As a part of the license application for a final repository for spent nuclear fuel at Forsmark, the Swedish Nuclear Fuel and Waste Management Company (SKB) has undertaken a series of groundwater flow modelling studies. These represent time periods with different hydraulic conditions and the simulations carried out contribute to the overall evaluation of the repository design and long-term radiological safety. This report is concerned with the modelling of a repository at the Laxemar-Simpevarp site during periglacial and glacial climate conditions as a comparison to corresponding modelling carried out for Forsmark /Vidstrand et al. 2010/. The groundwater flow modelling study reported here comprises a coupled thermal-hydraulic-chemical (T-H-C) analysis of periods with periglacial and glacial climate conditions. The objective of the report is to provide bounding hydrogeological estimates at different stages during glaciation and deglaciation of a glacial cycle at Laxemar. Three cases with different climate conditions are analysed here: (i) Temperate case, (ii) Glacial case without permafrost, and (iii) Glacial case with permafrost. The glacial periods are transient and encompass approximately 13,000 years. The simulation results comprise pressures, Darcy fluxes, and water salinities, as well as advective transport performance measures obtained by particle tracking such as flow path lengths, travel times and flow-related transport resistances. The modelling is accompanied by a sensitivity study that addresses the impact of the following matters: the direction of the ice sheet advance and the bedrock hydraulic and transport properties

  15. Groundwater flow modelling of periods with periglacial and glacial climate conditions - Laxemar

    International Nuclear Information System (INIS)

    As a part of the license application for a final repository for spent nuclear fuel at Forsmark, the Swedish Nuclear Fuel and Waste Management Company (SKB) has undertaken a series of groundwater flow modelling studies. These represent time periods with different hydraulic conditions and the simulations carried out contribute to the overall evaluation of the repository design and long-term radiological safety. This report is concerned with the modelling of a repository at the Laxemar-Simpevarp site during periglacial and glacial climate conditions as a comparison to corresponding modelling carried out for Forsmark /Vidstrand et al. 2010/. The groundwater flow modelling study reported here comprises a coupled thermal-hydraulic-chemical (T-H-C) analysis of periods with periglacial and glacial climate conditions. The objective of the report is to provide bounding hydrogeological estimates at different stages during glaciation and deglaciation of a glacial cycle at Laxemar. Three cases with different climate conditions are analysed here: (i) Temperate case, (ii) Glacial case without permafrost, and (iii) Glacial case with permafrost. The glacial periods are transient and encompass approximately 13,000 years. The simulation results comprise pressures, Darcy fluxes, and water salinities, as well as advective transport performance measures obtained by particle tracking such as flow path lengths, travel times and flow-related transport resistances. The modelling is accompanied by a sensitivity study that addresses the impact of the following matters: the direction of the ice sheet advance and the bedrock hydraulic and transport properties

  16. Regression tree modeling of forest NPP using site conditions and climate variables across eastern USA

    Science.gov (United States)

    Kwon, Y.

    2013-12-01

    As evidence of global warming continue to increase, being able to predict forest response to climate changes, such as expected rise of temperature and precipitation, will be vital for maintaining the sustainability and productivity of forests. To map forest species redistribution by climate change scenario has been successful, however, most species redistribution maps lack mechanistic understanding to explain why trees grow under the novel conditions of chaining climate. Distributional map is only capable of predicting under the equilibrium assumption that the communities would exist following a prolonged period under the new climate. In this context, forest NPP as a surrogate for growth rate, the most important facet that determines stand dynamics, can lead to valid prediction on the transition stage to new vegetation-climate equilibrium as it represents changes in structure of forest reflecting site conditions and climate factors. The objective of this study is to develop forest growth map using regression tree analysis by extracting large-scale non-linear structures from both field-based FIA and remotely sensed MODIS data set. The major issue addressed in this approach is non-linear spatial patterns of forest attributes. Forest inventory data showed complex spatial patterns that reflect environmental states and processes that originate at different spatial scales. At broad scales, non-linear spatial trends in forest attributes and mixture of continuous and discrete types of environmental variables make traditional statistical (multivariate regression) and geostatistical (kriging) models inefficient. It calls into question some traditional underlying assumptions of spatial trends that uncritically accepted in forest data. To solve the controversy surrounding the suitability of forest data, regression tree analysis are performed using Software See5 and Cubist. Four publicly available data sets were obtained: First, field-based Forest Inventory and Analysis (USDA

  17. Species-specific climate response of oaks (Quercus spp. under identical environmental conditions

    Directory of Open Access Journals (Sweden)

    Sanders TGM

    2014-04-01

    Full Text Available Oak forests play a major role in Britain due to their economic, social and historic value. Sudden oak death and general decline symptoms have therefore caused major concerns in the forestry sector over the past decade. Several strategies have been proposed to preserve the economic and social value of oak forests, including the planting of native species with more southerly origins, or non-native species of oak that may be better suited to the projected climate of the future. The Ovington research plots, established 50 years ago at the Bedgebury Pinetum in southeast England, provided the opportunity to compare annual growth rates and climate-growth relationships of five oak species growing adjacent to each other on the same soil type and under the same climatic conditions. Clear differences were evident in annual increment and climate-growth responses for the five Quercus species. Growth rates were significantly lower (p<0.05 for the two species native to the UK (Q. petraea and Q. robur compared to the southern European and American species. A partitioning analysis using key climatic variables separates Q. coccinea from the other species due to its negative response to low temperatures. These results were confirmed by pointer year analysis. The analysis suggests that Q. robur is likely to be the more resilient of the two native species of oak to the future climate of southern Britain. Of the non-native species of oak evaluated, Q. coccinea represents an alternative species to Q. robur and Q. petraea on very dry, nutrient-poor sites. Q. palustris may also have some potential under current conditions for species diversification, but its requirement for higher summer precipitation than the other four species suggests that this potential may not be sustained as climate change progresses. However, if alternative species are selected as more resilient to climate change in terms of growth, it will be essential to consider a range of other issues

  18. Effects of climate and land use changes on groundwater resources in coastal aquifers.

    Science.gov (United States)

    Priyantha Ranjan, S; Kazama, So; Sawamoto, Masaki

    2006-07-01

    To estimate the freshwater loss in coastal aquifers due to salinisation, a numerical model based on the sharp interface assumption has been introduced. The developed methodology will be useful in areas where limited hydrological data are available. This model will elaborate on the changes in fresh groundwater loss with respect to climate change, land use pattern and hydrologic soil condition. The aridity index has been introduced to represent the variations in precipitation and temperature. The interesting finding is that the deforestation leads to increase groundwater recharge in arid areas, because deforestation leads to reduce evapotranspiration even though it favors runoff. The combined climate and land use scenarios show that when the aridity index is less than 60, the agricultural lands give higher groundwater recharge than other land use patterns for all hydrologic soil conditions. The calculated recharge was then used to estimate the freshwater-saltwater interface and percentage of freshwater loss due to salinity intrusion. We found that in arid areas, the fresh groundwater loss increases as the percentage of forest cover increases. The combined effects of deforestation and aridity index on fresh groundwater loss show that deforestation causes an increase in the recharge and existing fresh groundwater resource in areas having low precipitation and high temperature (arid climates). PMID:16305816

  19. Is bias correction of Regional Climate Model (RCM) simulations possible for non-stationary conditions?

    Science.gov (United States)

    Teutschbein, Claudia; Seibert, Jan

    2014-05-01

    Regional Climate Models (RCMs) are commonly used in climate-change impact studies to transfer large-scale Global Climate Model (GCM) values to smaller scales and to provide more detailed regional information. There is, however, the problem that RCM simulations often show considerable deviations from local observations due to systematic and random model errors. This issue has caused the development of several correction approaches, that can be classified according to their degree of complexity and include simple-to-apply methods such as linear transformations but also more advanced methods such as distribution mapping. Most of these common correction approaches are based on the assumption that RCM errors do not change over time. It is in principle not possible to test whether this underlying assumption of error stationarity is actually fulfilled for future climate conditions. In this contribution, however, we show that it is possible to evaluate how well correction methods perform for conditions different from those that they were calibrated to. This can be done with the relatively simple differential split-sample test, originally proposed by Klemeš ["Operational testing of hydrological simulation models", Hydrological Sciences Journal 31, no. 1 (1986): 13-24]. For five Swedish catchments, precipitation and temperature time series from 15 different ERA40-driven RCM simulations were corrected with different commonly-used bias correction methods. We then performed differential split-sample tests by dividing the data series into cold and warm respective dry and wet years. This enabled us to cross-evaluate the performance of different correction procedures under systematically varying climate conditions. The differential split-sample test identified major differences in the ability of the applied correction methods to reduce model errors and to cope with non-stationary biases. More advanced correction methods performed better, whereas large deviations remained for

  20. Analysis of a Solar Cooling System for Climatic Conditions of Five Different Cities of Saudi Arabia

    Directory of Open Access Journals (Sweden)

    M. Mujahid Rafique

    2016-01-01

    Full Text Available Air high in humidity leads to uncomfortable conditions and promotes the growth of different fungi and bacteria, which may cause health problems. The control of moisture content in the air using traditional air conditioning techniques is not a suitable option due to large consumption of primary energy and hence emission of greenhouse gases. The evaporative cooling technology is a cost effective and eco-friendly alternative but can provide thermal comfort conditions only under low humidity conditions. However, the evaporative cooling method can be used effectively in conjunction with desiccant dehumidifiers for better control of humidity. Such systems can control the temperature and humidity of the air independently and can effectively utilize the low-grade thermal energy resources. In this paper, the theoretical analysis of desiccant based evaporative cooling systems is carried out for five cities in Saudi Arabia (Jeddah, Jazan, Riyadh, Hail, and Dhahran. It has been observed that the coefficient of performance (COP of the system varies from 0.275 to 0.476 for different locations. The water removal capacity of the desiccant wheel is at its maximum for the climatic conditions of Jazan and at its minimum for Hail. The effect of climatic conditions of five cities on regeneration temperature, air mass flow rate, and potential of solar energy has been evaluated using RET Screen software.

  1. Comparison of winter wheat yield sensitivity to climate variables under irrigated and rain-fed conditions

    Science.gov (United States)

    Xiao, Dengpan; Shen, Yanjun; Zhang, He; Moiwo, Juana P.; Qi, Yongqing; Wang, Rende; Pei, Hongwei; Zhang, Yucui; Shen, Huitao

    2015-11-01

    Crop simulation models provide alternative, less time-consuming, and cost-effective means of determining the sensitivity of crop yield to climate change. In this study, two dynamic mechanistic models, CERES (Crop Environment Resource Synthesis) and APSIM (Agricultural Production Systems Simulator), were used to simulate the yield of wheat (Triticum aestivum L.) under well irrigated (CFG) and rain-fed (YY) conditions in relation to different climate variables in the North China Plain (NCP). The study tested winter wheat yield sensitivity to different levels of temperature, radiation, precipitation, and atmospheric carbon dioxide (CO2) concentration under CFG and YY conditions at Luancheng Agro-ecosystem Experimental Stations in the NCP. The results from the CERES and APSIM wheat crop models were largely consistent and suggested that changes in climate variables influenced wheat grain yield in the NCP. There was also significant variation in the sensitivity of winter wheat yield to climate variables under different water (CFG and YY) conditions. While a temperature increase of 2°C was the threshold beyond which temperature negatively influenced wheat yield under CFG, a temperature rise exceeding 1°C decreased winter wheat grain yield under YY. A decrease in solar radiation decreased wheat grain yield under both CFG and YY conditions. Although the sensitivity of winter wheat yield to precipitation was small under the CFG, yield decreased significantly with decreasing precipitation under the rainfed YY treatment. The results also suggest that wheat yield under CFG linearly increased by ≈3.5% per 60 ppm (parts per million) increase in CO2 concentration from 380 to 560 ppm, and yield under YY increased linearly by ≈7.0% for the same increase in CO2 concentration.

  2. Game theory and corporate governance: conditions for effective stewardship of companies exposed to climate change risks

    OpenAIRE

    Kruitwagen, L; Madani, K.; Caldecott, B; Workman, MHW

    2016-01-01

    Engagement between investors and corporate boards has been suggested as a pathway to mitigate stranded asset and climate change risks. Debate is ongoing as to whether divestment or active ownership strategies are more appropriate to deliver longterm value and environmental sustainability. The paper tests the effectiveness of owner engagement strategies by studying the conditions for cooperation between investors and their companies. Characteristics of investors and compan...

  3. Climate conditions in the westernmost Mediterranean over the last two millennia: An integrated biomarker approach

    OpenAIRE

    Nieto-Moreno, V.; Martínez-Ruiz, F.; Willmott, V.; García-Orellana, J.; P. Masqué; Sinninghe Damsté, J.S.

    2013-01-01

    Climate conditions in the westernmost Mediterranean (Alboran Sea basin) over the last two millennia have been reconstructed through integration of molecular proxies applied for the first time in this region at such high resolution. Two temperature proxies, one based on isoprenoid membrane lipids of marine Thaumarchaeota (TEX86H-tetraether index of compounds consisting of 86 carbons) and the other on alkenones produced by haptophytes (U-37(K') ratio) were applied to reconstruct sea surface tem...

  4. Comparison of winter wheat yield sensitivity to climate variables under irrigated and rain-fed conditions

    Science.gov (United States)

    Xiao, Dengpan; Shen, Yanjun; Zhang, He; Moiwo, Juana P.; Qi, Yongqing; Wang, Rende; Pei, Hongwei; Zhang, Yucui; Shen, Huitao

    2016-09-01

    Crop simulation models provide alternative, less time-consuming, and cost-effective means of determining the sensitivity of crop yield to climate change. In this study, two dynamic mechanistic models, CERES (Crop Environment Resource Synthesis) and APSIM (Agricultural Production Systems Simulator), were used to simulate the yield of wheat ( Triticum aestivum L.) under well irrigated (CFG) and rain-fed (YY) conditions in relation to different climate variables in the North China Plain (NCP). The study tested winter wheat yield sensitivity to different levels of temperature, radiation, precipitation, and atmospheric carbon dioxide (CO2) concentration under CFG and YY conditions at Luancheng Agro-ecosystem Experimental Stations in the NCP. The results from the CERES and APSIM wheat crop models were largely consistent and suggested that changes in climate variables influenced wheat grain yield in the NCP. There was also significant variation in the sensitivity of winter wheat yield to climate variables under different water (CFG and YY) conditions. While a temperature increase of 2°C was the threshold beyond which temperature negatively influenced wheat yield under CFG, a temperature rise exceeding 1°C decreased winter wheat grain yield under YY. A decrease in solar radiation decreased wheat grain yield under both CFG and YY conditions. Although the sensitivity of winter wheat yield to precipitation was small under the CFG, yield decreased significantly with decreasing precipitation under the rainfed YY treatment. The results also suggest that wheat yield under CFG linearly increased by ≈3.5% per 60 ppm (parts per million) increase in CO2 concentration from 380 to 560 ppm, and yield under YY increased linearly by ≈7.0% for the same increase in CO2 concentration.

  5. Efficiency Prediction and Performance Characterization of Photovoltaic Solar Panel at Baghdad Climate Conditions

    OpenAIRE

    Shaymaa Alaulddin Mahdi; Emad Talib Hahsim; Abbas Hamid Sulaymon

    2013-01-01

    The performance of a solar cell under sun radiation is necessary to describe the electrical parameters of the cell. The Prova 200 solar panel analyzer is used for the professional testing of four solar cells at Baghdad climate conditions. Voltage -current characteristics of different area solar cells operated under solar irradiation for testing their quality and determining the optimal operational parameters for maximum electrical output were obtained. A correlation is developed between solar...

  6. DETERMINATION OF WATER AND DRY MATTER IN ORNAMENTAL TREES UNDER THE CLIMATIC CONDITIONS OF IASI

    Directory of Open Access Journals (Sweden)

    Carmen Lamban

    2015-12-01

    Full Text Available This paper presents some results concerning the determination of water and dry matter through the quantitative gravimetric method in ornamental trees (leaves and branches of Juniperus, Thuja, Chamaecyparis, Picea, Pinus, Abies, Pseudotzuga genera, under the climatic conditions of Iasi. The purpose of carrying on this work is to see if moisture of vegetative part remains under normal limits. The success of propagation, planting, transplanting of woody plants is largely dependant on the presence of water.

  7. The Association between Depression and Climatic Conditions in the Iran Way to Preventive of Depression

    OpenAIRE

    Lida Mirzakhani; Parinaz Poursafa

    2014-01-01

    Background: Neurotransmitters, such as dopamine and serotonin, play an undeniable role in the incidence of mental illnesses. Almost all humans will experience depression. Furthermore, most humans lack the ability to control and reduce depression, the disorder can lead to physical damage. The main goal of this study was to determine the association between distribution of depression and the climatic conditions in the Iran country. Methods: Spatial distribution maps of depression were plott...

  8. Evaluation of growth and flowering potential of rosa hybrida cultivars under Faisalabad climatic conditions

    International Nuclear Information System (INIS)

    Exotic cultivars of hybrid roses respond uncertainly to new habitat. It is necessary to explore the potential of the introduced cultivars to judge the suitability in a new habitat. In the present study, nine Rosa hybrida cultivars including Autumn Sunset, Ice Berg, Paradise, Angel Face, Louise Odier, Casino, Grand Margina, Handel and Gruss-an-Teplitz were evaluated for growth and yield attributed under the climatic conditions of Faisalabad. Results indicated that there was decreasing trend in the growth and flowering of the bushes as the temperature increased above 32 degree C and humidity decreased to 29 %. Number of flowers per bush and diameter of flower decreased as the temperature increased and humidity decreased in contrast to increment in height of the plant and num ber of primary branches per plant in succeeding months. Interaction between yield traits and months was also significant. Overall, significant variations were observed in each cultivar for length and number of petals per flower, number of prickles, fragrance, flower persistence life and color, bush shape and overall performance with respect to climatic conditions of Faisalabad. It is concluded that the cultivars 'Autumn Sunset' and Gruss-an-Teplitz performed better in climatic conditions of Faisalabad. (author)

  9. Climatic controls on diffuse groundwater recharge across Australia

    Directory of Open Access Journals (Sweden)

    O. V. Barron

    2012-05-01

    Full Text Available Reviews of field studies of groundwater recharge have attempted to investigate how climate characteristics control recharge, but due to a lack of data have not been able to draw any strong conclusions beyond that rainfall is the major determinant. This study has used numerical modeling for a range of Köppen-Geiger climate types (tropical, arid and temperate to investigate the effect of climate variables on recharge for different soil and vegetation types. For the majority of climate types the total annual rainfall had a weaker correlation with recharge than the rainfall parameters reflecting rainfall intensity. In regions with winter-dominated rainfall, annual recharge under the same annual rainfall, soils and vegetation conditions is greater than in regions with summer-dominated rainfall. The relative importance of climate parameters other than rainfall is higher for recharge under annual vegetation, but overall is highest in the tropical climate type. Solar radiation and vapour pressure deficit show a greater relative importance than mean annual daily mean temperature. Climate parameters have lowest relative importance in the arid climate type (with cold winters and the temperate climate type. For 75% of all considered cases of soil, vegetation and climate types recharge elasticity varies between 2 and 4, indicating a 20% to 40% change in recharge for a 10% change in annual rainfall Understanding how climate controls recharge under the observed historical climate allows more informed choices of analogue sites if they are to be used for climate change impact assessments.

  10. Estimating the influence of vegetation on net infiltration under future climatic conditions

    Science.gov (United States)

    Stothoff, S. A.

    2005-12-01

    Performance assessments of the proposed geologic repository at Yucca Mountain, Nevada, are sensitive to the net infiltration passing the root zone above the repository, an area of roughly 5 km2. The area of interest has a semiarid climate, ten washes in rugged topography, and shallow soils overlying fractured bedrock composed of silicic volcanic tuff. Mean annual net infiltration is uncertain but constrained under current climatic conditions, based on modeling and observations. Performance assessments that consider periods of one or more glacial cycles must address net infiltration under wetter and cooler future climatic conditions. Potential evapotranspiration under current climatic conditions is sufficiently large relative to mean annual precipitation that numerical simulators are relatively insensitive to how evapotranspiration is implemented in the model. Water passes from soil into the bedrock only over short periods while the soil is wet following large storms. Under wetter and cooler climatic conditions, the representation of evapotranspiration may be more important, particularly the component handling plant uptake. Plant uptake models from the crop science literature assume that the plants have a predictable growth pattern over a growing season and predictable rooting patterns. These assumptions, reasonable for agricultural situations with annual crops in deep soil, may be questionable or difficult to parameterize when considering uptake from long-lived shrubs in semiarid climates with shallow soils and strong interannual variation in rainfall. An adaptive vegetation model is proposed that allows vegetation to respond to environmental influences. The adaptive model allocates roots according to uptake, which is mediated by the environment, within limits set by genetic preferences. The model allows growth in wet periods and dieback in dry periods, and allocates roots within the bedrock fractures to the depth supported by moisture availability. Estimated mean

  11. Eco-hydrologic Modeling of Rangelands: Evaluating a New Carbon Allocation Approach and Simulating Ecosystem Response to Changing Climate and Management Conditions

    Science.gov (United States)

    Reyes, J. J.; Tague, C.; Choate, J. S.; Adam, J. C.

    2014-12-01

    More than one-third of the United States' land cover is comprised of rangelands, which support both forage production and livestock grazing. For grasses in both semi-arid and humid environments, small changes in precipitation and temperature, as well as grazing, can have disproportionately larger impacts on ecosystem processes. For example, these areas may experience large response pulses under highly variable precipitation and other potential future changes. The ultimate goal of this study is to provide information on the interactions between management activities, climate and ecosystem processes to inform sustainable rangeland management. The specific objectives of this paper are to (1) evaluate a new carbon allocation strategy for grasses and (2) test the sensitivity of this improved strategy to changes in climate and grazing strategies. The Regional Hydro-ecologic Simulation System (RHESSys) is a process-based, watershed-scale model that simulates hydrology and biogeochemical cycling with dynamic soil and vegetation modules. We developed a new carbon allocation algorithm for partitioning net primary productivity (NPP) between roots and leaves for grasses. The 'hybrid' approach represents a balance between preferential partitioning due to environmental conditions and age-related growth. We evaluated this new allocation scheme at the point-scale at a variety of rangeland sites in the U.S. using observed biomass measurements and against existing allocation schemes used in RHESSys. Additionally, changes in the magnitude, frequency, and intensity of precipitation and temperature were used to assess ecosystem responses using our new allocation scheme. We found that changes in biomass and NPP were generally more sensitive to changes in precipitation than changes in temperature. At more arid sites, larger percent reductions in historic baseline precipitation affected biomass and NPP more negatively. We incorporated grazing impacts through biomass removal. We found that

  12. Morpho-physiological features of human populations in the context of climatic--geographical conditions.

    Science.gov (United States)

    Belkin, Victor; Korostishevsky, Michael; Batsevich, Valery; Pavlovsky, Oleg; Volkov-Dubrovin, Vladimir; Kobyliansky, Eugene

    2012-09-01

    This paper is based on the data obtained in the course of population studies conducted in 33 geographical regions of the former USSR territory by the faculty of the Anuchin Research Institute and Museum of Anthropology, Lomonosov Moscow State University, between 1961 and 1991. The data resulting from study of 4386 male and 4626 female subjects aged 17 to 99 include head and body morphology, bone mineral density, blood oxygen saturation and blood biochemistry. We aimed at studying the link between the traits of a population and the climatic conditions of the area inhabited by this population. Individual characteristics of the subjects were normalized by age and sex, and factor analysis was used to reduce the number of cross-correlating features. As a result, several integral characteristics (factors) were identified: five body morphology-related factors, two head morphology-related factors, one bone mineral density-related factor, one blood oxygen saturation-related factor and three blood biochemistry-related factors. These factors explained 79.3%, 78.38%, 63.51%, 74.4% and 66.77% of the trait groups' variability, respectively. The correlation analysis between these factors and climatic indicators demonstrated that chest dimensions were the least tolerant to the climatic conditions among the morphological characteristics studied. Hemoglobin-protein ratios, as well as the factor that includes total cholesterol, were the most climate-dependent among the biochemical parameters. As far as our data show, blood serum oxygen saturation--the key factor determining the performance of the cardiovascular and respiratory systems--is also climate-dependent. PMID:23213926

  13. STRATEGIC DEVELOPMENT OF AGRARIAN SPHERE AND RECREATION IN THE ALTAI REGIONS, RUSSIA, UNDER REGIONAL CLIMATE CHANGE

    OpenAIRE

    KRASNOYAROVA B.A.; KHARLAMOVA N.F.; SHARABARINA S.N.; PLUTALOVA T.G.; INDYUKOVA M.A.; GARMS E.O.

    2015-01-01

    The object of research is the territory of the Altai regions of Russia, in particular, Altai Krai and the Republic of Altai. It combines cultural and natural landscapes of the zonal steppe and forest-steppe areas and mountain altitudinal belts distinguished by a variety of climatic conditions. The analysis of possible climate changes in the Altai region showed a predominant development of land aridization under the reduction of humidity under a significant regional warming. The climate change...

  14. Precipitation-climate sensitivity to initial conditions in an atmospheric general circulation model

    Energy Technology Data Exchange (ETDEWEB)

    Covey, C., LLNL

    1997-03-01

    Atmospheric climate, in contrast to weather, is traditionally considered to be determined by boundary conditions such as sea surface temperature (SST). To test this hypothesis, we examined annual mean precipitation from an ensemble of 20 general circulation model (GCM) simulations. Ensemble members were forced with identical 10-year series of SST and sea ice, but they began with slightly differing initial conditions. A surprisingly small proportion of the variance in the output is attributable to the effects of boundary forcing. This result-and similar evidence from smaller ensembles of other GCM simulations-implies that long-term precipitation variations are mostly unpredictable, even if SST forecasts are `perfect.`

  15. Waste biorefinery in arid/semi-arid regions.

    Science.gov (United States)

    Bastidas-Oyanedel, Juan-Rodrigo; Fang, Chuanji; Almardeai, Saleha; Javid, Usama; Yousuf, Ahasa; Schmidt, Jens Ejbye

    2016-09-01

    The utilization of waste biorefineries in arid/semi-arid regions is advisable due to the reduced sustainable resources in arid/semi-arid regions, e.g. fresh water and biomass. This review focuses on biomass residues available in arid/semi-arid regions, palm trees residues, seawater biomass based residues (coastal arid/semi-arid regions), and the organic fraction of municipal solid waste. The present review aims to describe and discuss the availability of these waste biomasses, their conversion to value chemicals by waste biorefinery processes. For the case of seawater biomass based residues it was reviewed and advise the use of seawater in the biorefinery processes, in order to decrease the use of fresh water. PMID:27072789

  16. Screening of efficient arbuscular mycorrhizal fungi for Azadirachta indica under nursery condition: a step towards afforestation of semi-arid region of western India

    Directory of Open Access Journals (Sweden)

    K. Banerjee

    2013-01-01

    Full Text Available To optimize nursery practices for efficient plant production procedures and to keep up to the ever growing demand of seedlings, identification of the most suitable species of arbuscular mycorrhizal fungi (AMF, specific for a given tree species, is clearly a necessary task. Sixty days old seedlings of Neem (Azadirachta indica A. Juss raised in root trainers were inoculated with six species of AMF and a mixed inoculum (consortia and kept in green house. Performances of the treatments on this tree species were evaluated in terms of growth parameters like plant height shoot collar diameter, biomass and phosphorous uptake capabilities. Significant and varied increase in the growth parameters and phosphorous uptake was observed for most of the AMF species against control. Consortia culture was found to be the best suited AMF treatment for A.indica, while Glomus intraradices and Glomus mosseae were the best performing single species cultures. It is the first time in the state of Gujarat that a wide variety of AMF species, isolated from the typical semi-arid region of western India, were tested for the best growth performance with one of the most important tree species for the concerned region.

  17. Impact of regional afforestation on climatic conditions in metropolitan areas: case study of Copenhagen

    Science.gov (United States)

    Stysiak, Aleksander Andrzej; Bergen Jensen, Marina; Mahura, Alexander

    2016-04-01

    Like most other places, European metropolitan areas will face a range of climate-related challenges over the next decades that may influence the nature of urban life across the continent. Under future urbanization and climate change scenarios the well-being and comfort of the urban population might become progressively compromised. In urban areas, the effects of the warming climate will be accelerated by combination of Urban Heat Island effect (UHI) and extreme heat waves. The land cover composition directly influences atmospheric variability, and can either escalate or downscale the projected changes. Vegetation, forest ecosystems in particular, are anticipated to play an important role in modulating local and regional climatic conditions, and to be vital factor in the process of adapting cities to warming climate. This study investigates the impact of forest and land-cover change on formation and development of temperature regimes in the Copenhagen Metropolitan Area (CPH-MA). Potential to modify the UHI effect in CPH-MA is estimated. Using 2009 meteorological data, and up-to-date 2012 high resolution land-cover data we employed the online integrated meteorology-chemistry/aerosols Enviro-HIRLAM (Environment - High Resolution Limited Area Model) modeling system to simulate air temperature (at 2 meter height) fields for a selected period in July 2009. Employing research tools (such as METGRAF meteorological software and Geographical Information Systems) we then estimated the influence of different afforestation and urbanization scenarios with new forests being located after the Danish national afforestation plan, after proximity to the city center, after dominating wind characteristics, and urbanization taking place as densification of the existing conurbation. This study showed the difference in temperature up to 3.25°C, and the decrease in the spatial extent of temperature fields up to 68%, depending on the selected scenario. Performed simulations demonstrated

  18. Climate change and future overwintering conditions of horticultural woody-plants in Finland

    Energy Technology Data Exchange (ETDEWEB)

    Laapas, M.; Jylhae, K.; Tuomenvirta, H. (Finnish Meteorological Inst., Helsinki (Finland))

    2012-07-01

    Climate in Finland offers challenging conditions for commercial horticulture. The short and insufficient growing season together with risky overwintering strongly limits species suitable for cultivation. The aim of this study was to examine the climatic conditions around Finland in the aspect of horticulture, focusing on processes relevant to woody plants and species with photoperiod controlled growth cessation, and how these conditions may be expected to change due to the projected global warming. For this, a set of temperature-related indices and threshold events were used. These indices represent the severity of coldness during winter, wintertime thaws, and frost events close to the onset and ending of the growing season. The combined results of 19 GCMs (General Circulation Model) from the CMIP3 (Coupled Model Intercomparison Project 3) multi-model data set under SRES-B1 and SRES-A2 (Special Report on Emission Scenarios) emission scenarios were used to produce the future projections. By mid-century our results suggest wintertime conditions with reduced cold stress, caused by less frequent and shorter periods of severe frost together with a rise in the extreme minimum temperature. Conversely, an increase in the number and intensity of wintertime thaw events leads to a higher risk in overwintering. Also the risk of spring frost damage is projected to decrease slightly, and the conditions for cold hardening process to improve, as the first autumnal frosts occur later. (orig.)

  19. Trend and climatic sensitivity of vegetation phenology in semiarid and arid ecosystems in the US Great Basin during 1982–2011

    Directory of Open Access Journals (Sweden)

    G. Tang

    2015-07-01

    Full Text Available We quantified the temporal trend and climatic sensitivity of vegetation phenology in dryland ecosystems in the US Great Basin during 1982–2011. Our results indicated that vegetation greenness in the Great Basin increased significantly during the study period, and this positive trend occurred in autumn but not spring and summer. Spatially, increases in vegetation greenness were more apparent in the northwestern, southeastern, and eastern Great Basin but less apparent in the central and southwestern Great Basin. In addition, the start of growing season (SOS was not advanced while the end of growing season (EOS was delayed significantly at a rate of 3.0 days per decade during the study period. The significant delay in EOS and lack of earlier leaf onset caused growing season length (GSL to increase at a rate of 3.0 days per decade during 1982–2011. Interestingly, we found that the variation of mean vegetation greenness in the period of March to November (SSA was not significantly correlated with its mean surface air temperature but was strongly correlated with its total precipitation. Seasonally, the variation of mean vegetation greenness in spring, summer, and autumn was mainly attributable to changes in pre-season precipitation in winter and spring. Nevertheless, climate warming played a strong role in extending GSL that in turn resulted in the upward trend in mean vegetation greenness during 1982–2011. Overall, our results suggested that changes in wintertime and springtime precipitation played a stronger role than temperature in affecting the interannual variability of vegetation greenness while climate warming was mainly responsible for the 30-year upward trend in the magnitudes of mean vegetation greenness in the dryland ecosystems during 1982–2011.

  20. Nitrogen partitioning in oak leaves depends on species, provenance, climate conditions and soil type.

    Science.gov (United States)

    Hu, B; Simon, J; Kuster, T M; Arend, M; Siegwolf, R; Rennenberg, H

    2013-01-01

    Climate-tolerant tree species and/or provenances have to be selected to ensure the high productivity of managed forests in Central Europe under the prognosticated climate changes. For this purpose, we studied the responses of saplings from three oak species (i.e. Quercus robur, Q. petraea and Q. pubescens) and provenances of different climatic origin (i.e. low or high rainfall, low or high temperature habitats) with regard to leaf nitrogen (N) composition as a measure of N nutrition. Saplings were grown in model ecosystems on either calcareous or acidic soil and subjected to one of four treatments (control, drought, air warming or a combination of drought and air warming). Across species, oak N metabolism responded to the influence of drought and/or air warming with an increase in leaf amino acid N concentration at the expense of structural N. Moreover, provenances or species from drier habitats were more tolerant to the climate conditions applied, as indicated by an increase in amino acid N (comparing species) or soluble protein N (comparing provenances within a species). Furthermore, amino acid N concentrations of oak leaves were significantly higher on calcareous compared to acidic soil. From these results, it can be concluded that seeds from provenances or species originating from drier habitats and - if available - from calcareous soil types may provide a superior seed source for future forest establishment. PMID:22934888

  1. Evolution and current state of our understanding of the role played in the climate system by land surface processes in semi-arid regions

    Science.gov (United States)

    Nicholson, Sharon E.

    2015-10-01

    The role of the land surface in climate and weather has been a major research focus since the 1970s. Since that time our understanding of the issue has greatly changed and many new themes in several disciplines are being considered. This article summarizes the changes in our understanding that have taken place in research on this topic and reviews principally papers that have appeared in the last two decades. Several other papers provide comprehensive reviews of literature that appeared prior to that time. The major changes that have occurred include 1) more sophisticated and rigorous analysis of desertification, 2) increased emphasis on hydrological processes, including the role of groundwater, 3) use of multi-model ensembles and regional models, 4) the emergence of the domain of ecohydrology, with emphasis on detailed feedbacks between water availability and vegetation, 5) examination of the hypothesis that vegetation feedback can produce abrupt climate change, 6) emphasis on the impacts on convective or synoptic-scale systems, and 7) consideration of the impact of aerosols, including the Saharan Air Layer. With the exception of desertification, each of these topics is reviewed.

  2. Impacts of Water Deficiency on Life History of Sitobion avenae Clones From Semi-arid and Moist Areas.

    Science.gov (United States)

    Dai, Peng; Liu, Deguang; Shi, Xiaoqin

    2015-10-01

    The climate warming trend appears to be evident with an increasing frequency of drought events in Shaanxi Province of China, which may have contributed to an increase in outbreaks of the English grain aphid, Sitobion avenae (Fabricius). To explore the potential effects of water-deficit stress on aphid outbreak risks, clones of S. avenae were collected from semi-arid and moist areas of Shaanxi. The life histories of collected clones were then compared on wheat under well-watered and moderately water-stressed conditions in the laboratory. Our results demonstrated that semi-arid area clones of S. avenae had longer developmental times, shorter reproductive times, lower fecundities, and lower net reproductive rates compared with moist area clones. Age-specific reproductive rates of moist area clones tended to be higher than those of semi-arid area clones. Significant differences between semi-arid and moist area clones were found for the survival functions when tested under water-stressed conditions, and semi-arid area clones tended to have a lower survival rate than moist area clones throughout their lives. "Population origin" (i.e., semi-arid and moist area clones) and "clone" together explained 62.74-96.56% of the total variance of tested life-history traits, suggesting the genetic basis for differentiation of clones from both areas. Significant differences in correlations, and selection differentials and gradients of life-history traits were also found between clones from both areas, providing further evidence of genetic basis for the life-history differentiation between them. Divergence between clones from both areas and its implications for S. avenae outbreaks are discussed. PMID:26453713

  3. Invited review: Influence of climatic conditions on the development, performance, and health of calves.

    Science.gov (United States)

    Roland, L; Drillich, M; Klein-Jöbstl, D; Iwersen, M

    2016-04-01

    The objective of this review is to provide the reader with an overview of thermoregulatory mechanisms and the influence of climatic conditions in different housing systems on the development, performance, and health of calves. Thermic stress is observed in association with extreme temperatures and large temperature variations, but other variables such as relative humidity and wind speed can also contribute to thermic stress. Thermoregulation in calves is similar to that in adult cattle, but especially dystocial calves are more prone to heat loss. Heat or cold stress results in direct economic losses because of increased calf mortality and morbidity, as well as indirect costs caused by reduced weight gain, performance, and long-term survival. The climatic conditions in a variety of housing systems, associated health problems, and strategies to mitigate thermic stress are discussed in this review. The goal of housing is to alleviate the effect of climate on calves and provide a microclimate. Adequate ventilation with fresh air is essential to reduce respiratory disease. Common practices such as raising calves in individual outdoor enclosures have been challenged lately. Recent research seeks to evaluate the suitability of group housing under practical, economic, and animal welfare considerations. Limited results for reducing thermic stress can be achieved by simple measures such as shades or shelter, but additional heat or cold stress relieving strategies can be required depending on the housing system. PMID:26874416

  4. Rainfall and net infiltration probabilities for future climate conditions at Yucca Mountain

    International Nuclear Information System (INIS)

    Performance assessment of repository integrity is a task rendered difficult because it requires predicting the future. This challenge has occupied many scientists who realize that the best assessments are required to maximize the probability of successful repository sitting and design. As part of a performance assessment effort directed by the EPRI, the authors have used probabilistic methods to assess the magnitude and timing of net infiltration at Yucca Mountain. A mathematical model for net infiltration previously published incorporated a probabilistic treatment of climate, surface hydrologic processes and a mathematical model of the infiltration process. In this paper, we present the details of the climatological analysis. The precipitation model is event-based, simulating characteristics of modern rainfall near Yucca Mountain, then extending the model to most likely values for different degrees of pluvial climates. Next the precipitation event model is fed into a process-based infiltration model that considers spatial variability in parameters relevant to net infiltration of Yucca Mountain. The model predicts that average annual net infiltration at Yucca Mountain will range from a mean of about 1 mm under present climatic conditions to a mean of at least 2.4 mm under full glacial (pluvial) conditions. Considerable variations about these means are expected to occur from year-to-year

  5. Simulating runoff under changing climatic conditions: Revisiting an apparent deficiency of conceptual rainfall-runoff models

    Science.gov (United States)

    Fowler, Keirnan J. A.; Peel, Murray C.; Western, Andrew W.; Zhang, Lu; Peterson, Tim J.

    2016-03-01

    Hydrologic models have potential to be useful tools in planning for future climate variability. However, recent literature suggests that the current generation of conceptual rainfall runoff models tend to underestimate the sensitivity of runoff to a given change in rainfall, leading to poor performance when evaluated over multiyear droughts. This research revisited this conclusion, investigating whether the observed poor performance could be due to insufficient model calibration and evaluation techniques. We applied an approach based on Pareto optimality to explore trade-offs between model performance in different climatic conditions. Five conceptual rainfall runoff model structures were tested in 86 catchments in Australia, for a total of 430 Pareto analyses. The Pareto results were then compared with results from a commonly used model calibration and evaluation method, the Differential Split Sample Test. We found that the latter often missed potentially promising parameter sets within a given model structure, giving a false negative impression of the capabilities of the model. This suggests that models may be more capable under changing climatic conditions than previously thought. Of the 282[347] cases of apparent model failure under the split sample test using the lower [higher] of two model performance criteria trialed, 155[120] were false negatives. We discuss potential causes of remaining model failures, including the role of data errors. Although the Pareto approach proved useful, our aim was not to suggest an alternative calibration strategy, but to critically assess existing methods of model calibration and evaluation. We recommend caution when interpreting split sample results.

  6. Spatiotemporal analysis and trends of aridity of Iberian Peninsula (1960-2010)

    Science.gov (United States)

    Paniagua, Luis L.; García, Abelardo; Moral, Francisco J.; Rebollo, Francisco J.

    2016-04-01

    In this study the aridity of the Iberian Peninsula was analysed, taking into account 45 stations in Spain and Portugal from 1960 to 2010. The De Martonne Index was considered. The goal of this study was to explore the spatial distribution and to determine monotonic trends and shift changes in annual aridity by using the Mann-Kendall test and the Seńs estimator. The spatially interpolated maps of the aridity indice were generated using the ordinary kriging algorithm in a geographic information system (GIS) environment. A great variability for Martonne Index was found, gathering from semiarid climates to extremely humid, although the former being the dominant type. 41 temporal series showed decreasing tendencies, 15 of them significant, belonging to all climate types, which indicates a increase in aridity during the research period. A shift in the aridity tendency has been observed around 1979, and a period of greater aridity started since.

  7. Impacts of Stream Flow and Climate Variability on Native and Invasive Woody Species in a Riparian Ecosystem of a Semi-Arid Region of the Great Plains, USA

    Science.gov (United States)

    Skolaut, K.; Awada, T.; Cherubini, P.; Schapaugh, A.

    2012-12-01

    Riparian ecosystems support diverse plant communities that exert direct and indirect biological, physical and chemical influence on, and are influenced by, adjacent water through both above and below-ground interactions. Historically, riparian areas of the northern Great Plains, US have been dominated by the native Populus deltoides (eastern cottonwood). This species relies on regular floods for regeneration and groundwater access for success. Over the past sixty years, changes in flow management and agricultural practices, coupled with climate variability and drought have altered stream flow and caused a dramatic decline in stream water yields and levels of groundwater. These and other biotic and biotic factors have promoted the expansion of the upland native woody species Juniperus virginiana (eastern redcedar), and the invasion of the non-native (introduced) Elaeagnus angustifolia (Russian olive) into riparian ecosystems. This invasion has further altered the water balance in the system and exasperated the problem of water scarcity with negative feedback on ecosystem services and growth of native woody species. The ability of P. deltoides to re-establish and grow is of concern for natural resource managers. Tree ring analysis of annual growth rates were used to determine 1) the responses P. deltoides and invasive J. virginiana and E. angustifulia to climate variability and stream flow regulation, and 2) the impacts of the two invasive species on the growth of native P. deltoides. Results show a dependency of growth for P. deltoides on the previous year summer temperature, and a less significant correlation to annual stream flow. J. virginiana showed the highest correlation to annual stream flow, as well as some dependency on the previous growing season precipitation. While the growth of both P. deltoides and J. virginiana displayed greater dependence on climatic factors, E. angustifolia displayed the lowest mean basal area growth and deviation from the growth. E

  8. A new large initial condition ensemble to assess avoided impacts in a climate mitigation scenario

    Science.gov (United States)

    Sanderson, B. M.; Tebaldi, C.; Knutti, R.; Oleson, K. W.

    2014-12-01

    It has recently been demonstrated that when considering timescales of up to 50 years, natural variability may play an equal role to anthropogenic forcing on subcontinental trends for a variety of climate indicators. Thus, for many questions assessing climate impacts on such time and spatial scales, it has become clear that a significant number of ensemble members may be required to produce robust statistics (and especially so for extreme events). However, large ensemble experiments to date have considered the role of variability in a single scenario, leaving uncertain the relationship between the forced climate trajectory and the variability about that path. To address this issue, we present a new, publicly available, 15 member initial condition ensemble of 21st century climate projections for the RCP 4.5 scenario using the CESM1.1 Earth System Model, which we propose as a companion project to the existing 40 member CESM large ensemble which uses the higher greenhouse gas emission future of RCP8.5. This provides a valuable data set for assessing what societal and ecological impacts might be avoided through a moderate mitigation strategy in contrast to a fossil fuel intensive future. We present some early analyses of these combined ensembles to assess to what degree the climate variability can be considered to combine linearly with the underlying forced response. In regions where there is no detectable relationship between the mean state and the variability about the mean trajectory, then linear assumptions can be trivially exploited to utilize a single ensemble or control simulation to characterize the variability in any scenario of interest. We highlight regions where there is a detectable nonlinearity in extreme event frequency, how far in the future they will be manifested and propose mechanisms to account for these effects.

  9. Impact of climate change on commercial sector air conditioning energy consumption in subtropical Hong Kong

    International Nuclear Information System (INIS)

    Past and future trend of electricity use for air conditioning in the entire commercial sector in subtropical climates using 1979-2008 measured meteorological data as well as predictions for 2009-2100 from a general circulation model (MIROC3.2-H) was investigated. Air conditioning consumption showed an increasing trend over the past 30 years from 1979 to 2008. Principal component analysis (PCA) of measured and predicted monthly mean dry-bulb temperature, wet-bulb temperature and global solar radiation was conducted to determine a new climatic index Z for 1979-2008 and future 92 years (2009-2100) based on two emissions scenarios B1 and A1B (low and medium forcing). Through regression analysis, electricity use in air conditioning for the 92-year period was estimated. For low forcing, average consumption in 2009-2038, 2039-2068 and 2069-2100 would be, respectively, 5.7%, 12.8% and 18.4% more than the 1979-2008 average, with a mean 12.5% increase for the entire 92-year period. Medium forcing showed a similar increasing trend, but 1-4% more. Standard deviations of the monthly air conditioning consumption were found to be smaller suggesting possible reduction in seasonal variations in future years.

  10. Assessing potential changes of chestnut productivity in Europe under future climate conditions

    Science.gov (United States)

    Calheiros, T.; Pereira, M. G.; Pinto, J. G.; Caramelo, L.; Gomes-Laranjo, J.; Dacamara, C. C.

    2012-04-01

    The European chestnut is cultivated for its nuts and wood. Several studies point to the dependency of chestnut productivity on specific soil and climate characteristics. For instance, this species dislikes chalky and poorly drained soils, appreciates sedimentary, siliceous and acidic to neutral soils. Chestnut trees also seems to appreciate annual mean values of sunlight spanning between 2400 and 2600 h, rainfall ranging between 600 and 1500 mm, mean annual temperature between 9 and 13°C, 27°C being the mean of the maximum temperature (Heiniger and Conedera, 1992; Gomes-Laranjo et al.,2008). The amount of heat between May and October must range between 1800°D and 2400°D (Dinis et al., 2011) . In Poland, the growing season is defined as the period of time when the mean 24-h temperature is greater than 5°C (Wilczynski and Podalski, 2007). In Portugal, maximum photosynthetic activity occurs at 24-28°C for adult trees, but exhibits more than 50% of termoinhibition when the air temperature is above 32°C, which is frequent during summer (Gomes- Laranjo et al., 2006, 2008). Recently Pereira et al (2011) identified a set of meteorological variables/parameters with high impact on chestnut productivity. The main purpose of this work is to assess the potential impacts of future climate change on chestnut productivity in Portugal as well as on European chestnut orchards. First, observed data from the European Climate assessment (ECA) and simulations with the Regional Circulation Model (RCM) COSMO-CLM for recent climate conditions are used to assess the ability of the RCM to model the actual meteorological conditions. Then, ensemble projections from the ECHAM5/COSMO-CLM model chain for two climate scenarios (A1B and B1) are used to estimate the values of relevant meteorological variables and parameters und future climate conditions. Simulated values are then compared with those obtained for present climate. Results point to changes in the spatial and temporal

  11. Characterizing climate predictability and model response variability from multiple initial condition and multi-model ensembles

    CERN Document Server

    Kumar, Devashish

    2016-01-01

    Climate models are thought to solve boundary value problems unlike numerical weather prediction, which is an initial value problem. However, climate internal variability (CIV) is thought to be relatively important at near-term (0-30 year) prediction horizons, especially at higher resolutions. The recent availability of significant numbers of multi-model (MME) and multi-initial condition (MICE) ensembles allows for the first time a direct sensitivity analysis of CIV versus model response variability (MRV). Understanding the relative agreement and variability of MME and MICE ensembles for multiple regions, resolutions, and projection horizons is critical for focusing model improvements, diagnostics, and prognosis, as well as impacts, adaptation, and vulnerability studies. Here we find that CIV (MICE agreement) is lower (higher) than MRV (MME agreement) across all spatial resolutions and projection time horizons for both temperature and precipitation. However, CIV dominates MRV over higher latitudes generally an...

  12. Adverse weather conditions for European wheat production will become more frequent with climate change

    DEFF Research Database (Denmark)

    Trnka, Miroslav; Rötter, Reimund P.; Ruiz-Ramos, Margarita;

    2014-01-01

    Europe is the largest producer of wheat, the second most widely grown cereal crop after rice. The increased occurrence and magnitude of adverse and extreme agroclimatic events are considered a major threat for wheat production. We present an analysis that accounts for a range of adverse weather...... events that might significantly affect wheat yield in Europe. For this purpose we analysed changes in the frequency of the occurrence of 11 adverse weather events. Using climate scenarios based on the most recent ensemble of climate models and greenhouse gases emission estimates, we assessed the...... probability of single and multiple adverse events occurring within one season. We showed that the occurrence of adverse conditions for 14 sites representing the main European wheat-growing areas might substantially increase by 2060 compared to the present (1981–2010). This is likely to result in more frequent...

  13. Earlier breeding, lower success: does the spatial scale of climatic conditions matter in a migratory passerine bird?

    Science.gov (United States)

    Grimm, Annegret; Weiß, Brigitte M; Kulik, Lars; Mihoub, Jean-Baptiste; Mundry, Roger; Köppen, Ulrich; Brueckmann, Tomas; Thomsen, Ruth; Widdig, Anja

    2015-12-01

    Following over 20 years of research on the climatic effects on biodiversity we now have strong evidence that climate change affects phenology, fitness, and distribution ranges of different taxa, including birds. Bird phenology likely responds to changes in local weather. It is also affected by climatic year-to-year variations on larger scales. Although such scale-related effects are common in ecology, most studies analyzing the effects of climate change were accomplished using climatic information on a single spatial scale. In this study, we aimed at determining the scale-dependent sensitivity of breeding phenology and success to climate change in a migratory passerine bird, the barn swallow (Hirundo rustica). For both annual broods, we investigated effects of local weather (local scale) and the North Atlantic Oscillation (NAO, large scale) on the timing of breeding and breeding success. Consistent with previous studies in migratory birds we found that barn swallows in Eastern Germany bred progressively earlier. At the same time, they showed reduced breeding success over time in response to recent climatic changes. Responses to climatic variation were observed on both local and large climatic scales, but they differed with respect to the ecological process considered. Specifically, we found that the timing of breeding was primarily influenced by large-scale NAO variations and to a lesser extent by local weather on the breeding grounds. Conversely, climatic conditions on the local scale affected breeding success, exclusively. The observed decrease in breeding success over years is likely a consequence of scale-related mismatches between climatic conditions during different breeding phases. This provides further evidence that a species' response of earlier breeding may not be enough to cope with climate change. Our results emphasize the importance of considering the response of ecological processes along different climatic scales in order to better understand the

  14. The Effect of Body Weight on Heat Strain Indices in Hot and Dry Climatic Conditions

    Directory of Open Access Journals (Sweden)

    Habibi

    2016-03-01

    Full Text Available Background Being overweight is a characteristic that may influence a person’s heat exchange. Objectives The purpose of this study was to assess the effect of body weight on heat strain indices in hot and dry climatic conditions. Materials and Methods This study was completed with a sample of 30 participants with normal weights, as well as 25 participants who were overweight. The participants were physically inactive for a period of 120 minutes in a climatic chamber with hot and dry conditions (22 - 32°C and with 40% relative humidity (RH.The physiological strain index (PSI and heat strain score index (HSSI questionnaires were used. Simultaneous measurements were completed during heat exposure for periods of five minutes. The resting periods acted as the initial measurements for 15 minutes. Results In both groups, oral temperature, heart rate, and thermal perceptual responses increased during heat exposure. The means and standard deviations of heart rate and oral temperature were gathered when participants were in hot and dry climatic conditions and were not physically active. The heart rates and oral temperatures were 79.21 ± 5.93 bpm and 36.70 ± 0.45°C, respectively, for those with normal weights. For overweight individuals, the measurements for heart rate and oral temperature reached 82.21 ± 8.9 bpm and 37.84 ± 0.37°C, respectively. Conclusions The results showed that, compared to participants with normal weights, physiological and thermal perceptual responses were higher in overweight participants. Therefore, overweight individuals should avoid hot/dry weather conditions to decrease the amount of heat strain.

  15. Variability of Blowing Dust Weather Frequency over Semi-Arid Areas of China (Baicheng, Jilin Province and Relationships with Climatic Factors During 1951 - 2006

    Directory of Open Access Journals (Sweden)

    Yun-Fei Wu

    2011-01-01

    Full Text Available We analyzed the variability of blowing dust weather frequency (BDWF and patterns in climatic factors over Baicheng for the period 1951 - 2006 in this study. The data showed that blowing dust over Baicheng occurs intensively during the spring and shows significant inter-decadal variability. One of the main findings is that the occurrence of blowing dust has significantly decreased after the mid-1980s. The mean wind speed (WS, diurnal temperature range (DTR, relative humidity (RH and precipitation at Baicheng during the spring show decreasing trends. The decreasing trends of the mean WS and DTR are significant at 99% confidence levels according to the t-test; the dataset also indicated a sharp decrease in WS occurred after the mid-1980s. The mean surface air temperature (SAT escalated in a fluctuating manner during 1951 - 2006. BDWF at Baicheng was significantly related to local WS, SAT and DTR during the spring [correlation coefficients (CCs are 0.41, -0.47 and 0.36, respectively]. The correlation between BDWF at Baicheng and selected climatic factors over the sand-dust source regions and transmission paths were also calculated. We found that BDWF is well correlated to the mean WS and SAT during the spring, with CCs of 0.45 and -0.48, respectively. The most likely causes for the dramatic decrease observed in BDWF after the mid-1980s were related to the adjustment of large-scale circulation patterns in response to a decrease of meridional temperature differences, the weakening of steering westerlies and the strengthening of downward motions that has occurred at the middle latitudes of eastern Eurasia in recent decades.

  16. Groundwater Supported Evapotranspiration within Glaciated Watersheds under Conditions of Climate Change

    Science.gov (United States)

    Person, M. A.; Winter, T. C.; Rosenberry, D. O.; Cohen, D.; Gutowski, W. J.; Dahlstrom, D.; Roy, P.; Emi, I.; Zabielski, V.; Wrigth, H.; Nieber, J.; Daannen, R.

    2004-05-01

    We analyze the effects of geology and geomorphology on surface water/groundwater interactions, evapotranspiration, and runoff generation under conditions of long-term climate change. Our analysis uses hydrologic data from the glaciated Crow Wing watershed in central Minnesota, USA, as well as saturated/unsaturated mathematical modeling. Analysis of historical water table (1970-1993) and lake level (1924--2002) records indicate that larger amplitude, longer period fluctuations occur within the upland portions of watersheds due to the response of the aquifer system to climatic fluctuations. Under dust-bowl type climatic conditions, lake and water table levels fell by as much as 2-4 meters in the uplands but by only a meter in the lowlands. The same pattern can be seen on millennial time scales. Analysis of Holocene lake core records indicate that Moody lake, located near the confluence of the Crow Wing and Mississippi rivers fell by as much as 4 meters between about 4400 and 7000 yr BP. During the same time period, water levels in Lake Mina, located near the watershed divide near Alexandria, MN, fell by about 15 m. These findings are consistent with analytical calculations that indicate that the response time and magnitude of water table and lake level fluctuations will be greatest near the water table divide of large watersheds. A sensitivity analysis was carried out using a transient saturated-unsaturated hydrologic model (HYDRAT2D) to study how aquifer hydraulic conductivity, land surface topography and watershed size can influence watertable fluctuations, westlands formation, evapotranspiration, and runoff. The models were run by recycling relatively wet (1985, 87 cm annual precipitation) climatic record over a period of 10 years followed by 20 years of a dryer (1976, 38~cm precipitation) and warmer climate record. Model results indicated that aquifer-supported evapotranspiration accounted for as much as 12 % (10 cm) of evapotranspiration. The highest hydraulic

  17. Climatic impacts of fresh water hosing under Last Glacial Maximum conditions: a multi-model study

    Directory of Open Access Journals (Sweden)

    M. Kageyama

    2012-08-01

    Full Text Available Fresh water hosing simulations, in which a fresh water flux is imposed in the North Atlantic to force fluctuations of the Atlantic Meridional Overturning Circulation, have been routinely performed, first to study the climatic signature of different states of this circulation, then, under present or future conditions, to investigate the potential impact of a partial melting of the Greenland ice sheet. The most compelling examples of climatic changes potentially related to AMOC abrupt variations, however, are found in high resolution palaeo-records from around the globe for the last glacial period. To study those more specifically, more and more fresh water hosing experiments have been performed under glacial conditions in the recent years. Here we compare an ensemble constituted by 11 such simulations run with 6 different climate models. All simulations follow a slightly different design but are sufficiently close in their design to be compared. All study the impact of a fresh water hosing imposed in the extra-tropical North Atlantic. Common features in the model responses to hosing are the cooling over the North Atlantic, extending along the sub-tropical gyre in the tropical North Atlantic, the southward shift of the Atlantic ITCZ and the weakening of the African and Indian monsoons. On the other hand, the expression of the bipolar see-saw, i.e. warming in the Southern Hemisphere, differs from model to model, with some restricting it to the South Atlantic and specific regions of the Southern Ocean while others simulate a wide spread Southern Ocean warming. The relationships between the features common to most models, i.e. climate changes over the North and tropical Atlantic, African and Asian monsoon regions, are further quantified. These suggest a tight correlation between the temperature and precipitation changes over the extra-tropical North Atlantic, but different pathways for the teleconnections between the AMOC/North Atlantic region and

  18. Climatic impacts of fresh water hosing under Last Glacial Maximum conditions: a multi-model study

    Directory of Open Access Journals (Sweden)

    M. Kageyama

    2013-04-01

    Full Text Available Fresh water hosing simulations, in which a fresh water flux is imposed in the North Atlantic to force fluctuations of the Atlantic Meridional Overturning Circulation, have been routinely performed, first to study the climatic signature of different states of this circulation, then, under present or future conditions, to investigate the potential impact of a partial melting of the Greenland ice sheet. The most compelling examples of climatic changes potentially related to AMOC abrupt variations, however, are found in high resolution palaeo-records from around the globe for the last glacial period. To study those more specifically, more and more fresh water hosing experiments have been performed under glacial conditions in the recent years. Here we compare an ensemble constituted by 11 such simulations run with 6 different climate models. All simulations follow a slightly different design, but are sufficiently close in their design to be compared. They all study the impact of a fresh water hosing imposed in the extra-tropical North Atlantic. Common features in the model responses to hosing are the cooling over the North Atlantic, extending along the sub-tropical gyre in the tropical North Atlantic, the southward shift of the Atlantic ITCZ and the weakening of the African and Indian monsoons. On the other hand, the expression of the bipolar see-saw, i.e., warming in the Southern Hemisphere, differs from model to model, with some restricting it to the South Atlantic and specific regions of the southern ocean while others simulate a widespread southern ocean warming. The relationships between the features common to most models, i.e., climate changes over the north and tropical Atlantic, African and Asian monsoon regions, are further quantified. These suggest a tight correlation between the temperature and precipitation changes over the extra-tropical North Atlantic, but different pathways for the teleconnections between the AMOC/North Atlantic region

  19. Effects of Climatic Conditions and Soil Properties on Cabernet Sauvignon Berry Growth and Anthocyanin Profiles

    Directory of Open Access Journals (Sweden)

    Guo Cheng

    2014-09-01

    Full Text Available Climatic conditions and soil type have significant influence on grape ripening and wine quality. The reported study was conducted in two “Cabernet Sauvignon (Vitis vinifera L.V” vineyards located in Xinjiang, a semiarid wine-producing region of China during two vintages (2011 and 2012. The results indicate that soil and climate affected berry growth and anthocyanin profiles. These two localities were within a distance of 5 km from each other and had soils of different physical and chemical composition. For each vineyard, the differences of anthocyanin concentrations, and parameters concerning berry growth and composition between the two years could be explained by different climatic conditions. Soil effect was studied by investigation of differences in berry composition and anthocyanin profiles between the two vineyards in the same year, which could be explained mainly by the different soil properties, vine water and nitrogen status. Specifically, the soils with less water and organic matter produced looser clusters, heavier berry skins and higher TSS, which contributed to the excellent performance of grapes. Compared with 2011, the increases in anthocyanin concentrations for each vineyard in 2012 could be attributed to smaller number of extreme temperature (>35 °C days and rainfall, lower vine water status and N level. The explanation for higher anthocyanin concentrations in grape skins from the soils with less water and organic matter could be the vine status differences, lighter berry weight and heavier skin weight at harvest. In particular, grapes from the soils with less water and organic matter had higher levels of 3′5′-substituded, O-methylated and acylated anthocyanins, which represented a positive characteristic conferring more stable pigmentation to the corresponding wine in the future. The present work clarifies the effects of climate and soil on berry growth and anthocyanin profiles, thus providing guidance for production of

  20. Thermal State Of Permafrost In Urban Environment Under Changing Climatic Conditions

    Science.gov (United States)

    Streletskiy, D. A.; Grebenets, V. I.; Kerimov, A. G.; Kurchatova, A.; Andruschenko, F.; Gubanov, A.

    2015-12-01

    Risks and damage, caused by deformation of building and constructions in cryolithozone, are growing for decades. Worsening of cryo-ecological situation and loss of engineering-geocryological safety are induced by both technogenic influences on frozen basement and climate change. In such towns on permafrost as Vorkuta, Dixon more than 60% of objects are deformed, in Yakutsk, Igarka- nearly 40%, in Norilsk, Talnakh, Mirnij 35%, in old indigenous villages - approximately 100%; more than 80% ground dams with frozen cores are in poor condition. This situation is accompanied by activation of dangerous cryogenic processes. For example in growing seasonally-thaw layer is strengthening frost heave of pipeline foundation: only on Yamburg gas condensate field (Taz Peninsula) are damaged by frost heave and cut or completely replaced 3000 - 5000 foundations of gas pipelines. Intensity of negative effects strongly depends on regional geocryology, technogenic loads and climatic trends, and in Arctic we see a temperature rise - warming, which cause permafrost temperature rise and thaw). In built areas heat loads are more diverse: cold foundations (under the buildings with ventilated cellars or near termosyphons) are close to warm areas with technogenic beddings (mainly sandy), that accumulate heat, close to underground collectors for communications, growing thaw zones around, close to storages of snows, etc. Note that towns create specific microclimate with higher air temperature. So towns are powerful technogenic (basically, thermal) presses, placed on permafrost; in cooperation with climate changes (air temperature rise, increase of precipitation) they cause permafrost degradation. The analysis of dozens of urban thermal fields, formed in variable cryological and soil conditions, showed, that nearly 70% have warming trend, 20% - cooling and in 10% of cases the situation after construction is stable. Triggered by warming of climate changes of vegetation, depth and temperature of

  1. Changes in hydrological regime under changed climate and forest conditions in mountainous basins in Slovakia

    Science.gov (United States)

    Hlavcova, Kamila; Roncak, Peter; Maliarikova, Marcela; Latkova, Tamara; Korbelova, Lenka

    2016-04-01

    The impacts of land use and climate change on hydrological regime have been an important field of research in recent decades, especially with respect to runoff formation. Land use directly impacts basic hydrological processes, such as evapotranspiration, infiltration and runoff. The study focuses on estimating impact of land use and climate changes on runoff generation in selected mountainous basins in Slovakia. Changes in land use were represented by changes in forest distribution and composition induced by changed climate. Two climate scenarios of the daily air temperatures, specific air humidity and precipitation (KNMI A1B and MPI A1B) regionally downscaled for the territory of Slovakia until the time horizon of 2075 were applied. For simulations of runoff and other components of hydrological balance under changed conditions a distributed rainfall-runoff model was used. The simulations were done with an emphasis on the parameterization of the land cover properties (spatially distributed model parameters) and calibration of global parameters of the hydrological model in changed conditions. The outcomes of the runoff simulations indicate that changes in the long-term mean monthly discharges are expected. During the winter and early spring periods, an increase in the long-term mean monthly runoff could be assumed. The period of an increase in runoff could occur from November/December to February/April. This increase could be caused by an increase in air temperature and a shift in the snow melting period from the spring months to the winter period. The period of a decrease in runoff could occur from March/April to September/November. The increase in winter runoff and the decrease in summer runoff are expected to be more extreme for the later time horizons.

  2. Organic Matter and Water Addition Enhance Soil Respiration in an Arid Region

    OpenAIRE

    Liming Lai; Jianjian Wang; Yuan Tian; Xuechun Zhao; Lianhe Jiang; Xi Chen; Yong Gao; Shaoming Wang; Yuanrun Zheng

    2013-01-01

    Climate change is generally predicted to increase net primary production, which could lead to additional C input to soil. In arid central Asia, precipitation has increased and is predicted to increase further. To assess the combined effects of these changes on soil CO2 efflux in arid land, a two factorial manipulation experiment in the shrubland of an arid region in northwest China was conducted. The experiment used a nested design with fresh organic matter and water as the two controlled par...

  3. The potential for cold climate conditions and permafrost in Forsmark in the next 60 000 years

    International Nuclear Information System (INIS)

    This report presents results of a study devoted to extend the current knowledge of the climate in Sweden in the next ∼60,000 years (60 ka). Specifically, the potential of cold climate and permafrost development in south-central Sweden, and in the Forsmark region, over this time horizon was investigated. The climate system is an interactive system consisting of five major components: the atmosphere, the hydrosphere, the cryo sphere, the land surface and the biosphere, forced or influenced by various external forcing mechanisms, of which the most important is the Sun. Also the direct effect of human activities on the climate system is considered an external forcing. The latitudinal and seasonal distribution of incoming solar radiation (insolation) varies on millennial time scales due to variations in the Earth's orbit and axial tilt. These variations, together with variations in the atmospheric CO2 concentration, are viewed as two main factors in determining the climate variation between interglacial (warmer) and glacial (colder) climates. Summer insolation at high northern latitudes is at a minimum 17 ka and 54 ka after present (AP). These periods were therefore identified as potential future periods of cold climate conditions in high northern latitudes in general and in south-central Sweden in particular. Due to human emissions of carbon to the atmosphere, the atmospheric CO2 concentration is currently 392 ppmv (2011 AD), a substantial increase as compared to the range of atmospheric CO2 concentrations of 180-295 ppmv found in ice cores for the last 400 ka. The future atmospheric CO2 concentration is determined by i) future human carbon emissions to the atmosphere, ii) possible emissions due to feedbacks in the climate system, and iii) by the global carbon cycle. To investigate the potential of cold climate conditions in south-central Sweden in the next 60 ka the future air temperature in Forsmark was estimated based on simulations with an Earth system model of

  4. The potential for cold climate conditions and permafrost in Forsmark in the next 60 000 years

    Energy Technology Data Exchange (ETDEWEB)

    Brandefelt, Jenny; Naeslund, Jens-Ove [Svensk Kaernbraenslehantering, Stockholm (Sweden); Zhang, Qiong [Dept. of Meteorology, Stockholm Univ., Stockholm (Sweden); Hartikainen, Juha [School of Engineering, Aalto Univ., Aalto (Finland)

    2013-05-15

    This report presents results of a study devoted to extend the current knowledge of the climate in Sweden in the next {approx}60,000 years (60 ka). Specifically, the potential of cold climate and permafrost development in south-central Sweden, and in the Forsmark region, over this time horizon was investigated. The climate system is an interactive system consisting of five major components: the atmosphere, the hydrosphere, the cryo sphere, the land surface and the biosphere, forced or influenced by various external forcing mechanisms, of which the most important is the Sun. Also the direct effect of human activities on the climate system is considered an external forcing. The latitudinal and seasonal distribution of incoming solar radiation (insolation) varies on millennial time scales due to variations in the Earth's orbit and axial tilt. These variations, together with variations in the atmospheric CO{sub 2} concentration, are viewed as two main factors in determining the climate variation between interglacial (warmer) and glacial (colder) climates. Summer insolation at high northern latitudes is at a minimum 17 ka and 54 ka after present (AP). These periods were therefore identified as potential future periods of cold climate conditions in high northern latitudes in general and in south-central Sweden in particular. Due to human emissions of carbon to the atmosphere, the atmospheric CO{sub 2} concentration is currently 392 ppmv (2011 AD), a substantial increase as compared to the range of atmospheric CO{sub 2} concentrations of 180-295 ppmv found in ice cores for the last 400 ka. The future atmospheric CO{sub 2} concentration is determined by i) future human carbon emissions to the atmosphere, ii) possible emissions due to feedbacks in the climate system, and iii) by the global carbon cycle. To investigate the potential of cold climate conditions in south-central Sweden in the next 60 ka the future air temperature in Forsmark was estimated based on

  5. Behavior of crushed rock aggregates used in road construction exposed to cold climate conditions

    Science.gov (United States)

    Kuznetsova, Elena; Pérez Fortes, Ana Patricia; Anastasio, Sara; Willy Danielsen, Svein

    2016-04-01

    Presently, about 90% of the aggregate production in Europe comes from naturally occurring resources: quarries and pits. Due to the increased demand for sand and gravel for construction purposes, not only in building but also in road construction, the last decade has seen a significant trend towards the use of more crushed rock aggregates. This resource has been more and more preferred to sand and gravel thanks to the significant technological development of its process and use phase. The performance of the aggregates is generally evaluated depending on three main factors: the geological origin (mineral composition, texture, structure, degree of weathering), the aggregate processing (crushing, sieving, washing, storing) and the user technology for a specific area of use (e.g. road construction, asphalt binders). Nevertheless climatic conditions should carefully be taken into account in application such as road construction. Large temperature gradients and high levels of humidity are known to significantly affect the performance of the material. Although the problem is, at least in the asphalt field, considered mostly from the binder point of view, this article aims to investigate the effect of aggregate properties on road performance in cold climatic conditions. Two different climatic areas will be taken into account: Norway and Spain. While both these countries are listed among the main European producers of aggregates, they represent significantly different climatic regions. While Norwegian weather is characterized by humid cold winters and relatively mild summers, Spain has temperate climate with cold regions in mountainous and internal areas. Both countries have been significantly affected by climate change with increasing temperature variations and instability. At the same time, similar winter maintenance measures, including the use of a considerable amount of solid and liquid chemicals to avoid ice formation (e.g. NaCl) and/or to provide better friction, are

  6. [Relationships between biochemical qualities of paddy rice and climate conditions in the Anning River Valley].

    Science.gov (United States)

    Peng, Guozhao; Bai, Jian; Wang, Jingbo

    2004-12-01

    Based on the experimental data of paddy rice planted geographically periodically without control in the Anning River Valley of Sichuan Province, this paper quantitatively analyzed the effects of meteorological conditions from 40 days before heading to ripeness on the biochemical qualities of paddy rice, and developed a model about the integrated relationships between biochemical qualities of paddy rice and mean temperature, daily range of temperature and daylight hours, which would be of significance both for the instruction of paddy distribution in the Anning River Valley and for improving rice qualities via adjusting planting time. The results showed that climate conditions had a great effect on the biochemical qualities of paddy rice, which was different in ways and in critical periods. The period when the correlation between some ingredients of rice and climate conditions was most significant was before or after, or from before to after full heading, which widened the existing knowledge about the period which was important for paddy rice qualities forming. Applying this finding in the Anning River Valley during 2002-2003, the accumulated high-grade paddy farming area stood at 73,000 hm2, 30,000 hm2 more than that in 2001, and brought 0.2 billion yuan increment to the peasants, promoting the development of high-grade paddy greatly. PMID:15825441

  7. Analysis of aridity indicators in the Deliblato Sands

    Directory of Open Access Journals (Sweden)

    Kadović Ratko

    2014-01-01

    Full Text Available Deliblato Sands are located in the southern part of Banat region in Vojvodina province. According to the estimated changes of basic climate parameters in this part of the Republic of Serbia during past decades very strong rise in annual air temperatures (T was registered, an average of 0.52°C per decade. This rise in temperature increased the potential evapotranspiration (PET, which together with precipitation can increase the degree of aridity of climate in the study area. However, in the same period an increase in annual precipitation sum (P was observed, an average of about 35 mm per decade, which may somewhat slow the aridisation of desert sands. Considering the nature, origin and significance of Deliblato Sands ecosystem, the main goal of this paper is to analyse the drought and aridity index (AI = P / PET, analyse the trend of aridisation process and its possible impact on ecosystems of this special nature reserve. Aridity index analyses were performed in meteorological stations Banatski Karlovac, Vrsac and Bela Crkva for the period 1981 - 2010 at the annual values and for the growing season. Results showed that Deliblato desert sands (Banatski Karlovac stand at a higher frequency of arid years (AI < 0.65 compared to locations of Vrsac and Bela Crkva. On the other hand, the level of aridity has considerably increased during the vegetation period in desert sands as well in its surroundings. This intensified aridity is the result of considerable increase of potential evapotranspiration (PET connected to season precipitation.

  8. Isotope study for relationship between surface and ground waters under a semi-arid climate: case of Souss-Massa catchment (South- West Morocco)

    International Nuclear Information System (INIS)

    This study summarizes the application of stable isotopes as tools to infer water sources in the region. Hydrogen and oxygen isotope signatures reveal a significant infiltration before evaporation, indicating a recent recharge from Atlas Mountain and infiltration of surface water along the oueds and in the alluvial cones at the margin of the Atlas basins. 18O, 2H and tritium values indicate a mixing between recent and old groundwaters. The old groundwaters encountered in deep wells are not connected to modern recharge, indicating that water followed a long flow path. The slight evaporation recorded by stable isotopes in water from the southern margin close to the Anti-Atlas mountains indicates that there groundwaters are subject to a drier climate, marking the Anti-Atlas Mountains, which form a barrier against the influence of the Sahara. The upstream watershed, which is the place of condensation, shows more characteristic 2H and 18O-depleted waters. This finding can be explained by the altitude and the continental effects. On the other hand, 2H and 18O-enriched waters values towards the ocean, show an evaporation effect near the condensation source or the irrigation returns, especially in the irrigated zones. The rain isotope values indicate a main recharge from the Atlasic Mountain, whereas the contribution of the local rains is negligible in downstream. (author)

  9. Isotope study for relationship between surface and groundwaters under a semi-arid climate: Case of Souss-Massa Catchment (South-West of Morocco)

    International Nuclear Information System (INIS)

    This study summarizes the application of stable isotopes as tools to infer water sources in the region. Hydrogen and oxygen isotope signatures reveal significant infiltration before evaporation, indicating recent recharge from the Atlas Mountains and infiltration of surface water along the oueds and in the alluvial fans at the margin of the Atlas basins. 18O, 2H and tritium values indicate a mixing between recent and old groundwaters. The old groundwaters encountered in deep wells are not connected to modern recharge, indicating that water followed a long flow path.The slight evaporation recorded by stable isotopes in water from the southern margin close to the Anti-Atlas mountains indicates that these groundwaters are subject to a drier climate, marking the Anti-Atlas Mountains, which form a barrier against the influence of the Sahara. The upstream watershed, which is the place of condensation, shows more characteristic 2H and 18O-depleted waters.This finding can be explained by the altitude and the continental effects. On the other hand, 2H and 18O-enriched waters values towards the ocean, show an evaporation effect near the condensation source or the irrigation returns, especially in the irrigated zones.The rain isotope values indicate a main recharge from the Atlas Mountains, whereas the contribution of the local rains is negligible in downstream. (author)

  10. Long term investigation of resveratrol content in moravian red wines in relation to climate conditions

    Czech Academy of Sciences Publication Activity Database

    Vrchotová, Naděžda; Tříska, Jan; Totušek, J.; Balík, J.

    Brno: Global change research centre, Academy of Sciences of the Czech Republic, v. v. i, 2013 - (Stojanov, R.; Žalud, Z.; Cudlín, P.; Farda, A.; Urban, O.; Trnka, M.), s. 251-254 ISBN 978-80-904351-8-6. [Global Change and Resilience. Brno (CZ), 22.05.2013-24.05.2013] R&D Projects: GA MŠk(CZ) ED1.1.00/02.0073 Institutional support: RVO:67179843 Keywords : resveratrol * moravian red wine * climatic conditions Subject RIV: EH - Ecology, Behaviour

  11. Small Scale Solar Cooling Unit in Climate Conditions of Latvia: Environmental and Economical Aspects

    OpenAIRE

    Jaunzems, D; Veidenbergs, I

    2010-01-01

    The paper contributes to the analyses from the environmental and economical point of view of small scale solar cooling system in climate conditions of Latvia. Cost analyses show that buildings with a higher cooling load and full load hours have lower costs. For high internal gains, cooling costs are around 1,7 €/kWh and 2,5 €/kWh for buildings with lower internal gains. Despite the fact that solar cooling systems have significant potential to reduce CO2 emissions due to a reduction of electri...

  12. Experimental and numerical evaluation of a solar passive cooling system under hot and humid climatic conditions

    Energy Technology Data Exchange (ETDEWEB)

    Rincon, Jose; Almao, Nastia [Universidad del Zulia, Lab. de Simulacion Computacional, Zulia (Venezuela); Gonzalez, Eduardo [Universidad del Zulia, Inst. de Investigaciones de la Facultad de Arquitectura, Zulia (Venezuela)

    2001-07-01

    The thermal performance of a solar passive cooling system (SPCS) under a hot and humid climate is experimentally and numerically evaluated. The experimental data were obtained from two full scale cells, with identical walls, but different roof configurations. One cell has a highly-insulated roof and the other has an SPCS incorporated consisting of a thermal mass (water), which is cooled by evaporation and long wave nocturnal radiation. The study was conducted taking into account the local climatic conditions of Maracaibo, a tropical city located in Venezuela. The numerical evaluation was accomplished using the computational code 'EVITA' which is based on the finite volume approach with high order bounded treatment of the convective terms. A PISO-like solution algorithm is used to solve the transient form of the continuity, momentum and energy equations. It has been demonstrated experimentally and numerically that under a hot and humid climate, it is possible to keep the indoor temperature below the outdoor temperature, using a passive cooling technique of a roof pond. The numerical results obtained using the model have demonstrated that the computational code used is a suitable cost-efficient alternative for the thermal performance evaluation of SPCS. (Author)

  13. Establishment and performance of an experimental green roof under extreme climatic conditions.

    Science.gov (United States)

    Klein, Petra M; Coffman, Reid

    2015-04-15

    Green roofs alter the surface energy balance and can help in mitigating urban heat islands. However, the cooling of green roofs due to evapotranspiration strongly depends on the climatic conditions, and vegetation type and density. In the Southern Central Plains of the United States, extreme weather events, such as high winds, heat waves and drought conditions pose challenges for successful implementation of green roofs, and likely alter their standard performance. The National Weather Center Experimental Green Roof, an interdisciplinary research site established in 2010 in Norman, OK, aimed to investigate the ecological performance and surface energy balance of green roof systems. Starting in May 2010, 26 months of vegetation studies were conducted and the radiation balance, air temperature, relative humidity, and buoyancy fluxes were monitored at two meteorological stations during April-October 2011. The establishment of a vegetative community trended towards prairie plant dominance. High mortality of succulents and low germination of grasses and herbaceous plants contributed to low vegetative coverage. In this condition succulent diversity declined. Bouteloua gracilis and Delosperma cooperi showed typological dominance in harsh climatic conditions, while Sedum species experienced high mortality. The plant community diversified through volunteers such as Euphorbia maculate and Portulaca maculate. Net radiation measured at a green-roof meteorological station was higher than at a control station over the original, light-colored roofing material. These findings indicate that the albedo of the green roof was lower than the albedo of the original roofing material. The low vegetative coverage during the heat and drought conditions in 2011, which resulted in the dark substrate used in the green roof containers being exposed, likely contributed to the low albedo values. Nevertheless, air temperatures and buoyancy fluxes were often lower over the green roof indicating

  14. Thermal comfort in air-conditioned mosques in the dry desert climate<