WorldWideScience

Sample records for brazil droughts modeling

  1. Evaluation of soil moisture and Palmer Drought Severity Index in Brazil

    Science.gov (United States)

    Rossato, Luciana; Antônio Marengo, José; Bassi Marinho Pires, Luciana

    2016-04-01

    Soil moisture is one of the main factors for the study of drought, climate and vegetation. In the case of drought, this is a regional phenomenon and affects food security more than any other natural disaster. Therefore, monitoring of different types of drought has been based on indexes that standardize on temporal and spatial scales. Currently, the monitoring of different types of drought is based on indexes that attempt to encapsulate on temporal and regional levels allowing thereby the comparison of water conditions in different areas. Therefore, in order to assess the impact of soil moisture during periods of drought, the Palmer Drought Severity Index was estimated for the entire Brazilian territory, using meteorological (precipitation and evapotranspiration) and soil (field capacity, permanent wilting point and water storage in the soil) data. The data field capacity and permanent wilting point were obtained from the physical properties of the soil, while the water storage in the soil was calculated considering the water balance model. Analyses were made for the years 2000 through 2014, which includes periods with and without occurrence of drought, respectively. The results showed that the PDSI had higher negative indices for the years 2003 and 2012 in Brazil's Northeast region, and this region was strongly affected by drought during those years. These indices can serve as a basis for assessing future drought projections, considering different scenarios. The results also show that soil moisture constitutes one of the limiting factors for obtaining high agricultural productivity, in order to reduce the effects caused by drought. Therefore, these indices can serve as a basis for assessing future drought projections, considering different scenarios. It would be desirable to assist decision makers in action plans with more effective strategies, allowing farmers to live with drought without losing their livelihood.

  2. Change in statistics of drought in a land use scenario for Brazil

    Science.gov (United States)

    Kilian, Markus; Chavez, Erik; Lucarini, Valerio

    2016-04-01

    The land use changes due to an intensified and expanding agricultural and industrial activity is affecting regional weather and climate in Brazil. We analyse the results of a land use change driven Weather and Research Forecasting Model (WRF) using classical drought indices and specific agricultural yield loss drought optimum indices. The objective is to assess changes in risk exposure driven by changes in weather patterns subject to different scenarios of land use changes in Brazil. The WRF model is driven by land use changes as well as the ECHAM5 climate model (with the A1B scenario) on a 60km and 30km grid. In order to determine the risk exposure of an important economic sector to changes in land use change we focus on maize as one of the principal crop grown in Brazil.

  3. The influence of oceanic basins on drought and ecosystem dynamics in Northeast Brazil

    International Nuclear Information System (INIS)

    The 2012 drought in Northeast Brazil was the harshest in decades, with potentially significant impacts on the vegetation of the unique semi-arid caatinga biome and on local livelihoods. Here, we use a coupled climate–vegetation model (CCM3-IBIS) to: (1) investigate the role of the Pacific and Atlantic oceans in the 2012 drought, and; (2) evaluate the response of the caatinga vegetation to the 2012 climate extreme. Our results indicate that anomalous sea surface temperatures (SSTs) in the Atlantic Ocean were the primary factor forcing the 2012 drought, with Pacific Ocean SST having a larger role in sustaining typical climatic conditions in the region. The drought strongly influenced net primary production in the caatinga, causing a reduction in annual net ecosystem exchange indicating a reduction in amount of CO2 released to the atmosphere. (letter)

  4. Managing the Health Impacts of Drought in Brazil

    Science.gov (United States)

    Sena, Aderita; Barcellos, Christovam; Freitas, Carlos; Corvalan, Carlos

    2014-01-01

    Drought is often a hidden risk with the potential to become a silent public health disaster. It is difficult to define precisely when it starts or when it is over, and although it is a climatological event, its impacts depend on other human activities, and are intensified by social vulnerability. In Brazil, half of all natural disaster events are drought related, and they cause half of the impacts in number of affected persons. One large affected area is the semiarid region of Brazil’s Northeast, which has historically been affected by drought. Many health and well-being indicators in this region are worse than the rest of the country, based on an analysis of 5565 municipalities using available census data for 1991, 2000 and 2010, which allowed separating the 1133 municipalities affected by drought in order to compare them with the rest of the country. Although great progress has been made in reducing social and economic vulnerability, climate change and the expected changes in the semiarid region in the next few decades call for a review of current programs, particularly in public health, and the planning of new interventions with local communities. This study reviews the literature, analyzes available data and identifies possible actions and actors. The aim is to ensure there will be sufficient and sustainable local adaptive capacity and resilience, for a population already living within the limits of environmental vulnerability. PMID:25325358

  5. Managing the Health Impacts of Drought in Brazil

    Directory of Open Access Journals (Sweden)

    Aderita Sena

    2014-10-01

    Full Text Available Drought is often a hidden risk with the potential to become a silent public health disaster. It is difficult to define precisely when it starts or when it is over, and although it is a climatological event, its impacts depend on other human activities, and are intensified by social vulnerability. In Brazil, half of all natural disaster events are drought related, and they cause half of the impacts in number of affected persons. One large affected area is the semiarid region of Brazil’s Northeast, which has historically been affected by drought. Many health and well-being indicators in this region are worse than the rest of the country, based on an analysis of 5565 municipalities using available census data for 1991, 2000 and 2010, which allowed separating the 1133 municipalities affected by drought in order to compare them with the rest of the country. Although great progress has been made in reducing social and economic vulnerability, climate change and the expected changes in the semiarid region in the next few decades call for a review of current programs, particularly in public health, and the planning of new interventions with local communities. This study reviews the literature, analyzes available data and identifies possible actions and actors. The aim is to ensure there will be sufficient and sustainable local adaptive capacity and resilience, for a population already living within the limits of environmental vulnerability.

  6. Water: Drought, Crisis and Governance in Australia and Brazil

    Directory of Open Access Journals (Sweden)

    Wilson Sousa Júnior

    2016-10-01

    Full Text Available Despite huge differences in population, household income and development levels, Australia and Brazil have some temporal convergences in their water governance systems. Over the last 20 years, both countries have significantly reformed their water policies and practices by introducing a legal foundation for more integrated and participatory catchment/basin management based on the best information available. A critical test of any water reform is how effective it is in meeting the challenges of extreme and unpredictable conditions of drought and floods, which are expected to increase under climate changes scenarios. This paper compared the contemporary water governance frameworks of Australia and Brazil in relation to three elements of Integrated Water Resources Management (IWRM: integration, participation, and information/knowledge. We focused on insights from Brazil’s recent drought and Australia’s fluctuating water crises to derive lessons and recommendations for future changes. Among the main recommendations, we stress the need for both systems to improve effective participation and to embrace a more comprehensive approach to cope with water scarcity in future scenarios. Furthermore, water related decisions should be based on a transparent and well informed process, and take into account the lessons from similar situations worldwide in order to avoid unnecessary or ineffective measures. As demonstrated in the Australian case during the Millennium Drought, the most effective initiatives were those involving government, the private sector and society to achieve a more sustainable consumption pattern in all sectors. There is much to learn from the Brazilian and Australia experiences in water reforms and crises, but it is imperative to understand the social, economic and environmental context within which these took place. Continuing to develop the capacity and willingness of researchers and policy makers to work together can make an

  7. Drought Duration Biases in Current Global Climate Models

    Science.gov (United States)

    Moon, Heewon; Gudmundsson, Lukas; Seneviratne, Sonia

    2016-04-01

    Several droughts in the recent past are characterized by their increased duration and intensity. In particular, substantially prolonged droughts have brought major societal and economic losses in certain regions, yet climate change projections of such droughts in terms of duration is subject to large uncertainties. This study analyzes the biases of drought duration in state-of-the-art global climate model (GCM) simulations from the 5th phase of Coupled Model Intercomparison Project (CMIP5). Drought durations are defined as negative precipitation anomalies and evaluated with three observation-based datasets in the period of 1901-2010. Large spread in biases of GCMs is commonly found in all regions, with particular strong biases in North East Brazil, Africa, Northern Australia, Central America, Central and Northern Europe, Sahel and Asia. Also in most regions, the interquartile range of bias lies below 0, meaning that the GCMs tend to underestimate drought durations. Meanwhile in some regions such as Western South America, the Amazon, Sahel, West and South Africa, and Asia, considerable inconsistency among the three observation-based datasets were found. These results indicate substantial uncertainties and errors in current GCMs for simulating drought durations as well as a large spread in observation-based datasets, both of which are found to be particularly strong in those regions that are often considered to be hot spots of projected future drying. The underlying sources of these uncertainties need to be identified in further study and will be applied to constrain GCM-based drought projections under climate change.

  8. Multi-model drought estimation using regional climate model output

    Science.gov (United States)

    McCabe, M. F.; Sung, B.; Evans, J. P.; Sheffield, J.

    2012-12-01

    Drought is a recurring climatic phenomenon in Australia and many other regions of the world. Apart from the considerable social and health repercussions that widespread drought has at a community level, there are major implications to the landscape, economy and water resources sectors. One of the key outputs in drought characterisation is determining the degree, extent and severity of the actual drought. However, there exist a range of techniques to quantify drought (each with its own definition) that adds to the level of uncertainty in accurate estimation. To examine the range and variability in multi-model drought prediction, a study of drought characteristics is undertaken, focusing on one of Australia's most significant agricultural regions: the Murray Darling Basin (MDB). Common drought indices including the Reconnaissance Drought Index (RDI), Standard Runoff Index (SRI), Soil Moisture Percentiles (SMP) and Palmer Drought Severity Index (PDSI) were derived using output from a high resolution regional climate simulation of the MDB for the period from 1985 to 2008. Spatial and temporal analyses were conducted by comparing these indices across regional scales. A severity-area-duration analysis and drought clustering approach were also used to characterize the extent and severity of these events across south-eastern Australia. Overall it was found that the four drought indices responded similarly to precipitation anomalies and successfully captured the major droughts over the nearly 25 years of simulation. The recent Australian drought from 2002-2008 was the most severe as shown by various analyses. Indeed, the Murray Darling Basin experienced contiguous moderate to extreme drought conditions for long periods, covering almost 100% of both the Darling and Murray Basins. Analysis of results also showed that the duration of droughts varied greatly between indices, as drought assessments using soil moisture parameters tended to recover in response to precipitation at

  9. Spatiotemporal drought forecasting using nonlinear models

    Science.gov (United States)

    Vasiliades, Lampros; Loukas, Athanasios

    2010-05-01

    Spatiotemporal data mining is the extraction of unknown and implicit knowledge, structures, spatiotemporal relationships, or patterns not explicitly stored in spatiotemporal databases. As one of data mining techniques, forecasting is widely used to predict the unknown future based upon the patterns hidden in the current and past data. In order to achieve spatiotemporal forecasting, some mature analysis tools, e.g., time series and spatial statistics are extended to the spatial dimension and the temporal dimension, respectively. Drought forecasting plays an important role in the planning and management of natural resources and water resource systems in a river basin. Early and timelines forecasting of a drought event can help to take proactive measures and set out drought mitigation strategies to alleviate the impacts of drought. Despite the widespread application of nonlinear mathematical models, comparative studies on spatiotemporal drought forecasting using different models are still a huge task for modellers. This study uses a promising approach, the Gamma Test (GT), to select the input variables and the training data length, so that the trial and error workload could be greatly reduced. The GT enables to quickly evaluate and estimate the best mean squared error that can be achieved by a smooth model on any unseen data for a given selection of inputs, prior to model construction. The GT is applied to forecast droughts using monthly Standardized Precipitation Index (SPI) timeseries at multiple timescales in several precipitation stations at Pinios river basin in Thessaly region, Greece. Several nonlinear models have been developed efficiently, with the aid of the GT, for 1-month up to 12-month ahead forecasting. Several temporal and spatial statistical indices were considered for the performance evaluation of the models. The predicted results show reasonably good agreement with the actual data for short lead times, whereas the forecasting accuracy decreases with

  10. Model-based scenarios of Mediterranean droughts

    Directory of Open Access Journals (Sweden)

    M. Weiß

    2007-11-01

    Full Text Available This study examines the change in current 100-year hydrological drought frequencies in the Mediterranean in comparison to the 2070s as simulated by the global model WaterGAP. The analysis considers socio-economic and climate changes as indicated by the IPCC scenarios A2 and B2 and the global general circulation model ECHAM4. Under these conditions today's 100-year drought is estimated to occur 10 times more frequently in the future over a large part of the Northern Mediterranean while in North Africa, today's 100-year drought will occur less frequently. Water abstractions are shown to play a minor role in comparison to the impact of climate change, but can intensify the situation.

  11. Probabilistic assessment of agricultural droughts using graphical models

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    Ramadas, Meenu; Govindaraju, Rao S.

    2015-07-01

    Agricultural droughts are often characterized by soil moisture in the root zone of the soil, but crop needs are rarely factored into the analysis. Since water needs vary with crops, agricultural drought incidences in a region can be characterized better if crop responses to soil water deficits are also accounted for in the drought index. This study investigates agricultural droughts driven by plant stress due to soil moisture deficits using crop stress functions available in the literature. Crop water stress is assumed to begin at the soil moisture level corresponding to incipient stomatal closure, and reaches its maximum at the crop's wilting point. Using available location-specific crop acreage data, a weighted crop water stress function is computed. A new probabilistic agricultural drought index is then developed within a hidden Markov model (HMM) framework that provides model uncertainty in drought classification and accounts for time dependence between drought states. The proposed index allows probabilistic classification of the drought states and takes due cognizance of the stress experienced by the crop due to soil moisture deficit. The capabilities of HMM model formulations for assessing agricultural droughts are compared to those of current drought indices such as standardized precipitation evapotranspiration index (SPEI) and self-calibrating Palmer drought severity index (SC-PDSI). The HMM model identified critical drought events and several drought occurrences that are not detected by either SPEI or SC-PDSI, and shows promise as a tool for agricultural drought studies.

  12. Teleconnection mechanisms of northeast Brazil droughts: modeling and empirical evidence Mecanismos de teleconexões do nordeste do Brasil: modelagem numérica e evidência epirica

    Directory of Open Access Journals (Sweden)

    Fred Kucharski

    2008-06-01

    Full Text Available Targeted numerical modelling experimaents are conducted to complement the previous empirical diagnostics of circulation mechanisms leading from sea surface temperature (SST departures in the equatorial Pacific in January to anomalies in the March-April rainy season of Brazil's Nordeste. A weak interhemispheric northward directed SST gradient in the Atlantic favors a more southerly position of the hydrostatically controlled low pressure trough, embedded in which is the Intertropical Convergence Zone (ITCZ, which is the main rainbearing system for the Nordeste. In addition, anomalously warm waters in the equatorial Pacific in January tend to be followed by Nordeste drought. The underlying chain of causalities has been explored by empirical diagnostics and numerical modelling. During El Nino years, an upper-tropospheric wave train extends from the equatorial eastern Pacific to the tropical North Atlantic, affecting the patterns of upper-tropospheric topography and divergence, and hence of vertical motion over the Atlantic. This leads to a weaker meridional pressure gradient on the equatorward flank of the North Atlantic subtropical high, weaker North Atlantic tradewinds, an anomalously far northerly ITCZ position and thus Nordeste drought. The previous empirical diagnostics are overall supported by the modelling experiments.Experimentos específicos de modelagem numérica foram conduzidos para complementar diagnósticos empíricos realizados anteriormente dos mecanismos da circulação que relacionam anomalias na temperatura das águas superficiais do Pacífico equatorial em janeiro com as chuvas subsequentes em março-abril no Nordeste. Um gradiente térmico fraco (no sentido norte no Atlântico favorece a uma posição mais meridional do cavado de baixa pressão, controlado hidrostaticamente, dentro do qual se encontra a Zona de Convergência Inter-Tropical (ITCZ, que é a principal fonte de chuvas para o norte do Nordeste. Além disso,

  13. The 2014 southeast Brazil austral summer drought: regional scale mechanisms and teleconnections

    Science.gov (United States)

    Coelho, Caio A. S.; de Oliveira, Cristiano Prestrelo; Ambrizzi, Tércio; Reboita, Michelle Simões; Carpenedo, Camila Bertoletti; Campos, José Leandro Pereira Silveira; Tomaziello, Ana Carolina Nóbile; Pampuch, Luana Albertani; Custódio, Maria de Souza; Dutra, Lívia Marcia Mosso; Da Rocha, Rosmeri P.; Rehbein, Amanda

    2016-06-01

    The southeast region of Brazil experienced in austral summer 2014 a major drought event leading to a number of impacts in water availability for human consumption, agricultural irrigation and hydropower production. This study aims to perform a diagnostic analysis of the observed climate conditions during this event, including an inspection of the occurred precipitation anomalies in the context of previous years, and an investigation of possible relationships with sea surface temperatures and atmospheric circulation patterns. The sea surface temperature analysis revealed that the southwestern South Atlantic Ocean region near the coast of southeast Brazil showed strong negative association with precipitation over southeast Brazil, indicating that increased sea temperatures in this ocean region are consistent with reduced precipitation as observed in summer 2014. The circulation analysis revealed prevailing anti-cyclonic anomalies at lower levels (850 hPa) with northerly anomalies to the west of southeast Brazil, channeling moisture from the Amazon towards Paraguay, northern Argentina and southern Brazil, and drier than normal air from the South Atlantic Ocean towards the southeast region of Brazil. This circulation pattern was found to be part of a large-scale teleconnection wave train linked with the subsidence branch of the Walker circulation in the tropical east Pacific, which in turn was generated by an anomalous tropical heat source in north/northeastern Australia. A regional Hadley circulation with an ascending branch to the south of the subsidence branch of the Walker circulation in the tropical east Pacific was identified as an important component connecting the tropical and extratropical circulation. The ascending branch of this Hadley circulation in the south Pacific coincided with an identified Rossby wave source region, which contributed to establishing the extratropical component of the large-scale wave train connecting the south Pacific and the Atlantic

  14. Transient convection over the Amazon-Bolivia region and the dynamics of drought over Northeast Brazil

    Science.gov (United States)

    Buchmann, J.; Leitedasilvadias, P.; Moura, A. D.

    1985-01-01

    A two layer, nonlinear, equatorial beta-plane model, in p-coordinates is used to study the atmospheric response to a large scale prescribed heat source varying in time. The heat source is meant to represent a convective burst with total duration of approximately 48 hours over the Amazon/Bolivia region. The boundary conditions used are meridional velocity zero at 60 deg S, omega w = 0 at the top and zero geometric velocity at the lower boundary. Sensitivity study was done which includes initial state at rest, compared with realistic initial flow. The scale of the heat source is 1500 km in latitude and longitude and it is centered at 10 deg S. Special attention is paid to the distribution and intensity of the induced vertical motion. The model is integrated for two days and the preliminary results show agreement with the observed 200 mb flow. Of interest is the establishment of a trough and descending motion to the northeast of the heat source. A conjucture is thus made that the Amazon heat source and its fluctuations bear some relationship with the drought problem over Northeast Brazil.

  15. Modeling drought impact occurrence based on meteorological drought indices in Europe

    Science.gov (United States)

    Stagge, James H.; Kohn, Irene; Tallaksen, Lena M.; Stahl, Kerstin

    2015-11-01

    There is a vital need for research that links meteorological drought indices with drought impacts felt on the ground. Previously, this link has been estimated based on experience or defined based on very narrow impact measures. This study expands on earlier work by showing the feasibility of relating user-provided impact reports with meteorological drought indices, the Standardized Precipitation Index and the Standardized Precipitation-Evapotranspiration Index, through logistic regression, while controlling for seasonal and interannual effects. Analysis includes four impact types, spanning agriculture, energy and industry, public water supply, and freshwater ecosystem across five European countries. Statistically significant climate indices are retained as predictors using step-wise regression and used to compare the most relevant drought indices and accumulation periods across different impact types and regions. Agricultural impacts are explained by 2-12 month anomalies, though anomalies greater than 3 months are likely related to agricultural management practices. Energy and industrial impacts, typically related to hydropower and energy cooling water, respond slower (6-12 months). Public water supply and freshwater ecosystem impacts are explained by a more complex combination of short (1-3 month) and seasonal (6-12 month) anomalies. The resulting drought impact models have both good model fit (pseudo-R2 = 0.225-0.716) and predictive ability, highlighting the feasibility of using such models to predict drought impact likelihood based on meteorological drought indices.

  16. Drought prediction using a wavelet based approach to model the temporal consequences of different types of droughts

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    Maity, Rajib; Suman, Mayank; Verma, Nitesh Kumar

    2016-08-01

    Droughts are expected to propagate from one type to another - meteorological to agricultural to hydrological to socio-economic. However, they do not possess a universal, straightforward temporal dependence. Rather, assessment of one type of drought (successor) from another (predecessor) is a complex problem depending on the basin's physiographic and climatic characteristics, such as, spatial extent, topography, land use, land cover and climate regime. In this paper, a wavelet decomposition based approach is proposed to model the temporal dependence between different types of droughts. The idea behind is to separate the rapidly and slowly moving components of drought indices. It is shown that the temporal dependence of predecessor (say meteorological drought) on the successor (say hydrological drought) can be better captured at its constituting components level. Such components are obtained through wavelet decomposition retaining its temporal correspondence. Thus, in the proposed approach, predictand drought index is predicted using the decomposed components of predecessor drought. Several alternative models are investigated to arrive at the best possible model structure for predicting different types of drought. The proposed approach is found to be very useful for foreseeing the agricultural or hydrological droughts knowing the meteorological drought status, offering the scope for better management of drought consequences. The mathematical framework of the proposed approach is general in nature and can be applied to different basins. However, the limitation is the requirement of region/catchment specific calibration of some parameters before using the proposed model, which is not very difficult and uncommon though.

  17. Drought

    NARCIS (Netherlands)

    Quevauviller, P.; Lanen, Van Henny A.J.

    2014-01-01

    Drought is one of the most extreme weather-related natural hazards. It differs from other hydrometeorological extremes in several ways. It develops gradually and usually over large areas (transnational), mostly resulting from a prolonged period (from months to years) of below-normal precipitation

  18. A quantitative analysis to objectively appraise drought indicators and model drought impacts

    Science.gov (United States)

    Bachmair, S.; Svensson, C.; Hannaford, J.; Barker, L. J.; Stahl, K.

    2016-07-01

    coverage. The predictions also provided insights into the EDII, in particular highlighting drought events where missing impact reports may reflect a lack of recording rather than true absence of impacts. Overall, the presented quantitative framework proved to be a useful tool for evaluating drought indicators, and to model impact occurrence. In summary, this study demonstrates the information gain for drought monitoring and early warning through impact data collection and analysis. It highlights the important role that quantitative analysis with impact data can have in providing "ground truth" for drought indicators, alongside more traditional stakeholder-led approaches.

  19. A quantitative analysis to objectively appraise drought indicators and model drought impacts

    Directory of Open Access Journals (Sweden)

    S. Bachmair

    2015-09-01

    . The predictions also provided insights into the EDII, in particular highlighting drought events where missing impact reports reflect a lack of recording rather than true absence of impacts. Overall, the presented quantitative framework proved to be a useful tool for evaluating drought indicators, and to model impact occurrence. In summary, this study demonstrates the information gain for drought monitoring and early warning through impact data collection and analysis, and highlights the important role that quantitative analysis with impacts data can have in providing "ground truth" for drought indicators alongside more traditional stakeholder-led approaches.

  20. Representation of drought frequency in Southern South America performed by 14 CMIP5 models. Drought risk implications and perspectives towards future projections

    Science.gov (United States)

    Rivera, J. A.; Penalba, O. C.

    2012-12-01

    Drought frequency estimation is a key variable for drought risk assessment. The aim of this research is to evaluate how well the global climate models (GCMs) represent the drought frequencies in Southern South America (south of 20°S). For that purpose, we used the Standardized Precipitation Index (SPI), which quantifies the number of standard deviations that the accumulated rainfall in a given time scale deviates from the average value of a location in a particular period. The SPI is one of the drought indices most widely used worldwide, and one of the best suited for the study area. In order to build this index, monthly rainfall data were obtained from the CLARIS LPB Data Base for 120 of its stations, which were subjected to quality control procedures and have less than 10% of missing values. The SPI was computed for the period 1979-2008 on a time scale of 12 months, which represents long-term droughts. This procedure was also applied to the simulated precipitation from 14 CMIP5 GCMs over the study area. Two types of comparisons were performed, the first one for drought frequencies without taking into account the different drought classes and the second one for the frequencies of moderate, severe and extreme drought events. This second comparison is important given that drought risk was evaluated through a weighted index based in drought frequencies, which was constructed as a sum of drought classes -moderate, severe and extreme- with a weighting scheme. Most of the regions with moderate to high observed drought frequencies are located in the western and southern portions of La Plata Basin and over Patagonia region, while lower observed drought frequencies were obtained for Northern Argentina, Southern Brazil and Paraguay. This spatial pattern is barely reproduced by the modeled frequencies, and in some cases major differences exist. In order to analyze these differences, we performed a regional assessment of the SPI time series, which showed that the time series

  1. Productivity and drought tolerance of cassava cultivars in the Coastal Tablelands of Northeastern Brazil

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    Luciana Marques de Carvalho

    2016-05-01

    Full Text Available ABSTRACT: Ten cassava cultivars were grown in the field and evaluated to identify the most adapted to the Coastal Tablelands of northeast Brazil. The cultivars showed differences in proline and chlorophyll contents, plant height, number of leaves and branches, canopy area and root production, however they did not differ on photosynthetic rates. Cultivars 'Tianguá' and '9783-13' presented lower root yield, whereas 'BRS Tapioqueira' and 'Irará' had the highest root yield. Few leaves coupled with the highest water use efficiency for CO2 assimilation was found in 'BRS Kiriris' in contrast to 'BRS Jarina' and '9783-13'. 'BRS Caipira' had high proline content in both Umbaúba and Frei Paulo areas, traits usually associated to drought tolerance, that contribute to the adaptation. It is also important to consider that cultivar 'BRS Caipira' was the first to present increase in chlorophyll content after extended period of drought, that indicates a faster recovery after dry season. Furthermore, the results indicated that the most adapted cultivars for cultivation in this area are 'Irará', 'BRS Tapioqueira', 'BRS Kiriris' and 'BRS Caipira'.

  2. Socioeconomic Drought in a Changing Climate: Modeling and Management

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    AghaKouchak, Amir; Mehran, Ali; Mazdiyasni, Omid

    2016-04-01

    Drought is typically defined based on meteorological, hydrological and land surface conditions. However, in many parts of the world, anthropogenic changes and water management practices have significantly altered local water availability. Socioeconomic drought refers to conditions whereby the available water supply cannot satisfy the human and environmental water needs. Surface water reservoirs provide resilience against local climate variability (e.g., droughts), and play a major role in regional water management. This presentation focuses on a framework for describing socioeconomic drought based on both water supply and demand information. We present a multivariate approach as a measure of socioeconomic drought, termed Multivariate Standardized Reliability and Resilience Index (MSRRI; Mehran et al., 2015). This model links the information on inflow and surface reservoir storage to water demand. MSRRI integrates a "top-down" and a "bottom-up" approach for describing socioeconomic drought. The "top-down" component describes processes that cannot be simply controlled or altered by local decision-makers and managers (e.g., precipitation, climate variability, climate change), whereas the "bottom-up" component focuses on the local resilience, and societal capacity to respond to droughts. The two components (termed, Inflow-Demand Reliability (IDR) indicator and Water Storage Resilience (WSR) indicator) are integrated using a nonparametric multivariate approach. We use this framework to assess the socioeconomic drought during the Australian Millennium Drought (1998-2010) and the 2011-2014 California Droughts. MSRRI provides additional information on socioeconomic drought onset, development and termination based on local resilience and human demand that cannot be obtained from the commonly used drought indicators. We show that MSRRI can be used for water management scenario analysis (e.g., local water availability based on different human water demands scenarios). Finally

  3. A hybrid spatiotemporal drought forecasting model for operational use

    Science.gov (United States)

    Vasiliades, L.; Loukas, A.

    2010-09-01

    Drought forecasting plays an important role in the planning and management of natural resources and water resource systems in a river basin. Early and timelines forecasting of a drought event can help to take proactive measures and set out drought mitigation strategies to alleviate the impacts of drought. Spatiotemporal data mining is the extraction of unknown and implicit knowledge, structures, spatiotemporal relationships, or patterns not explicitly stored in spatiotemporal databases. As one of data mining techniques, forecasting is widely used to predict the unknown future based upon the patterns hidden in the current and past data. This study develops a hybrid spatiotemporal scheme for integrated spatial and temporal forecasting. Temporal forecasting is achieved using feed-forward neural networks and the temporal forecasts are extended to the spatial dimension using a spatial recurrent neural network model. The methodology is demonstrated for an operational meteorological drought index the Standardized Precipitation Index (SPI) calculated at multiple timescales. 48 precipitation stations and 18 independent precipitation stations, located at Pinios river basin in Thessaly region, Greece, were used for the development and spatiotemporal validation of the hybrid spatiotemporal scheme. Several quantitative temporal and spatial statistical indices were considered for the performance evaluation of the models. Furthermore, qualitative statistical criteria based on contingency tables between observed and forecasted drought episodes were calculated. The results show that the lead time of forecasting for operational use depends on the SPI timescale. The hybrid spatiotemporal drought forecasting model could be operationally used for forecasting up to three months ahead for SPI short timescales (e.g. 3-6 months) up to six months ahead for large SPI timescales (e.g. 24 months). The above findings could be useful in developing a drought preparedness plan in the region.

  4. 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 ...

  5. ENSO informed Drought Forecasting Using Nonhomogeneous Hidden Markov Chain Model

    Science.gov (United States)

    Kwon, H.; Yoo, J.; Kim, T.

    2013-12-01

    The study aims at developing a new scheme to investigate the potential use of ENSO (El Niño/Southern Oscillation) for drought forecasting. In this regard, objective of this study is to extend a previously developed nonhomogeneous hidden Markov chain model (NHMM) to identify climate states associated with drought that can be potentially used to forecast drought conditions using climate information. As a target variable for forecasting, SPI(standardized precipitation index) is mainly utilized. This study collected monthly precipitation data over 56 stations that cover more than 30 years and K-means cluster analysis using drought properties was applied to partition regions into mutually exclusive clusters. In this study, six main clusters were distinguished through the regionalization procedure. For each cluster, the NHMM was applied to estimate the transition probability of hidden states as well as drought conditions informed by large scale climate indices (e.g. SOI, Nino1.2, Nino3, Nino3.4, MJO and PDO). The NHMM coupled with large scale climate information shows promise as a technique for forecasting drought scenarios. A more detailed explanation of large scale climate patterns associated with the identified hidden states will be provided with anomaly composites of SSTs and SLPs. Acknowledgement This research was supported by a grant(11CTIPC02) from Construction Technology Innovation Program (CTIP) funded by Ministry of Land, Transport and Maritime Affairs of Korean government.

  6. Missing data imputation of climate datasets: implications to modeling extreme drought events

    Directory of Open Access Journals (Sweden)

    Gláucia Tatiana Ferrari

    2014-03-01

    Full Text Available Time series from weather stations in Brazil have several missing data, outliers and spurious zeroes. In order to use this dataset in risk and meteorological studies, one should take into account alternative methodologies to deal with these problems. This article describes the statistical imputation and quality control procedures applied to a database of daily precipitation from meteorological stations located in the State of Parana, Brazil. After imputation, the data went through a process of quality control to identify possible errors, such as: identical precipitation over seven consecutive days and precipitation values that differ significantly from the values in neighboring weather stations. Next, we used the extreme value theory to model agricultural drought, considering the maximum number of consecutive days with precipitation below 7 mm for the period between January and February, in the main soybean agricultural regions in the State of Parana.

  7. Future meteorological drought: projections of regional climate models for Europe

    Science.gov (United States)

    Stagge, James; Tallaksen, Lena; Rizzi, Jonathan

    2015-04-01

    In response to the major European drought events of the last decade, projecting future drought frequency and severity in a non-stationary climate is a major concern for Europe. Prior drought studies have identified regional hotspots in the Mediterranean and Eastern European regions, but have otherwise produced conflicting results with regard to future drought severity. Some of this disagreement is likely related to the relatively coarse resolution of Global Climate Models (GCMs) and regional averaging, which tends to smooth extremes. This study makes use of the most current Regional Climate Models (RCMs) forced with CMIP5 climate projections to quantify the projected change in meteorological drought for Europe during the next century at a fine, gridded scale. Meteorological drought is quantified using the Standardized Precipitation Index (SPI) and the Standardized Precipitation-Evapotranspiration Index (SPEI), which normalize accumulated precipitation and climatic water balance anomaly, respectively, for a specific location and time of year. By comparing projections for these two indices, the importance of precipitation deficits can be contrasted with the importance of evapotranspiration increases related to temperature changes. Climate projections are based on output from CORDEX (the Coordinated Regional Climate Downscaling Experiment), which provides high resolution regional downscaled climate scenarios that have been extensively tested for numerous regions around the globe, including Europe. SPI and SPEI are then calculated on a gridded scale at a spatial resolution of either 0.44 degrees (~50 km) or 0.11 degrees (~12.5km) for the three projected emission pathways (rcp26, rcp45, rcp85). Analysis is divided into two major sections: first validating the models with respect to observed historical trends in meteorological drought from 1970-2005 and then comparing drought severity and frequency during three future time periods (2011-2040, 2041-2070, 2071-2100) to the

  8. Drought Patterns Forecasting using an Auto-Regressive Logistic Model

    Science.gov (United States)

    del Jesus, M.; Sheffield, J.; Méndez Incera, F. J.; Losada, I. J.; Espejo, A.

    2014-12-01

    Drought is characterized by a water deficit that may manifest across a large range of spatial and temporal scales. Drought may create important socio-economic consequences, many times of catastrophic dimensions. A quantifiable definition of drought is elusive because depending on its impacts, consequences and generation mechanism, different water deficit periods may be identified as a drought by virtue of some definitions but not by others. Droughts are linked to the water cycle and, although a climate change signal may not have emerged yet, they are also intimately linked to climate.In this work we develop an auto-regressive logistic model for drought prediction at different temporal scales that makes use of a spatially explicit framework. Our model allows to include covariates, continuous or categorical, to improve the performance of the auto-regressive component.Our approach makes use of dimensionality reduction (principal component analysis) and classification techniques (K-Means and maximum dissimilarity) to simplify the representation of complex climatic patterns, such as sea surface temperature (SST) and sea level pressure (SLP), while including information on their spatial structure, i.e. considering their spatial patterns. This procedure allows us to include in the analysis multivariate representation of complex climatic phenomena, as the El Niño-Southern Oscillation. We also explore the impact of other climate-related variables such as sun spots. The model allows to quantify the uncertainty of the forecasts and can be easily adapted to make predictions under future climatic scenarios. The framework herein presented may be extended to other applications such as flash flood analysis, or risk assessment of natural hazards.

  9. A system dynamics model of human-water interaction in anthropogenic droughts

    Science.gov (United States)

    Blair, Peter; Buytaert, Wouter

    2016-04-01

    Modelling is set to be a key part of socio-hydrology's quest to understand the dynamics and long-term consequences of human-water interactions. As a subject in its infancy, still learning the questions to ask, conceptual models are of particular use in trying to understand the general nature of human-water systems. The conceptual model of Di Baldassarre et al. (2013), which investigates human-flood interactions, has been widely discussed, prompting great steps forward in understanding and coverage of socio-hydrology. The development of further conceptual models could generate further discussion and understanding. Flooding is one archetypal example of a system of human-water interaction; another is the case of water stress and drought. There has been a call to recognise and understand anthropogenic drought (Aghakouchak et al. 2015), and so this study investigates the nature of the socio-hydrological dynamics involved in these situations. Here we present a system dynamics model to simulate human-water interactions in the context of water-stressed areas, where drought is induced via a combination of lower than usual water availability and relatively high water use. It is designed based on an analysis of several case-studies where recent droughts have occurred, or where the prospect of drought looms. The locations investigated are Spain, Southeast Brazil, Northeast China and California. The numerical system dynamics model is based on causal loop, and stocks and flows diagrams, which are in turn developed from the qualitative analysis of the different cases studied. The study uses a comparative approach, which has the advantage of eliciting general system characteristics from the similarities between cases, while using the differences to determine the important factors which lead to different system behaviours. References: Aghakouchak, A., Feldman, D., Hoerling, M., Huxman, T., Lund, J., 2015. Recognize anthropogenic drought. Nature, 524, pp.409-411. Di Baldassarre, G

  10. Modeling drought impact occurrence based on climatological drought indices for four European countries

    Science.gov (United States)

    Stagge, James H.; Kohn, Irene; Tallaksen, Lena M.; Stahl, Kerstin

    2014-05-01

    The relationship between atmospheric conditions and the likelihood of a significant drought impact has, in the past, been difficult to quantify, particularly in Europe where political boundaries and language have made acquiring comprehensive drought impact information difficult. As such, the majority of studies linking meteorological drought with the occurrence or severity of drought impacts have previously focused on specific regions, very detailed impact types, or both. This study describes a new methodology to link the likelihood of drought impact occurrence with climatological drought indices across different European climatic regions and impact sectors using the newly developed European Drought Impact report Inventory (EDII), a collaborative database of drought impact information (www.geo.uio.no/edc/droughtdb/). The Standardized Precipitation Index (SPI) and Standardized Precipitation-Evapotranspiration Index (SPEI) are used as predictor variables to quantify meteorological drought severity over prior time periods (here 1, 2, 3, 6, 9, 12, and 24 months are used). The indices are derived using the gridded WATCH Forcing Datasets, covering the period 1958-2012. Analysis was performed using logistic regression to identify the climatological drought index and accumulation period, or linear combination of drought indices, that best predicts the likelihood of a documented drought impact, defined by monthly presence/absence. The analysis was carried out for a subset of four European countries (Germany, UK, Norway, Slovenia) and four of the best documented impact sectors: Public Water Supply, Agriculture and Livestock Farming, Energy and Industry, and Environmental Quality. Preliminary results show that drought impacts in these countries occur most frequently due to a combination of short-term (2-6 month) precipitation deficits and long-term (12-24 month) potential evapotranspiration anomaly, likely associated with increased temperatures. Agricultural drought impacts

  11. Modeling drought impact occurrence based on climatological drought indices for four European countries

    Science.gov (United States)

    Stagge, James H.; Kohn, Irene; Tallaksen, Lena M.; Stahl, Kerstin

    2014-05-01

    The relationship between atmospheric conditions and the likelihood of a significant drought impact has, in the past, been difficult to quantify, particularly in Europe where political boundaries and language have made acquiring comprehensive drought impact information difficult. As such, the majority of studies linking meteorological drought with the occurrence or severity of drought impacts have previously focused on specific regions, very detailed impact types, or both. This study describes a new methodology to link the likelihood of drought impact occurrence with climatological drought indices across different European climatic regions and impact sectors using the newly developed European Drought Impact report Inventory (EDII), a collaborative database of drought impact information (www.geo.uio.no/edc/droughtdb/). The Standardized Precipitation Index (SPI) and Standardized Precipitation-Evapotranspiration Index (SPEI) are used as predictor variables to quantify meteorological drought severity over prior time periods (here 1, 2, 3, 6, 9, 12, and 24 months are used). The indices are derived using the gridded WATCH Forcing Datasets, covering the period 1958-2012. Analysis was performed using logistic regression to identify the climatological drought index and accumulation period, or linear combination of drought indices, that best predicts the likelihood of a documented drought impact, defined by monthly presence/absence. The analysis was carried out for a subset of four European countries (Germany, UK, Norway, Slovenia) and four of the best documented impact sectors: Public Water Supply, Agriculture and Livestock Farming, Energy and Industry, and Environmental Quality. Preliminary results show that drought impacts in these countries occur most frequently due to a combination of short-term (2-6 month) precipitation deficits and long-term (12-24 month) potential evapotranspiration anomaly, likely associated with increased temperatures. Agricultural drought impacts

  12. Evaluation of drought propagation in an ensemble mean of large-scale hydrological models

    Directory of Open Access Journals (Sweden)

    A. F. Van Loon

    2012-11-01

    Full Text Available Hydrological drought is increasingly studied using large-scale models. It is, however, not sure whether large-scale models reproduce the development of hydrological drought correctly. The pressing question is how well do large-scale models simulate the propagation from meteorological to hydrological drought? To answer this question, we evaluated the simulation of drought propagation in an ensemble mean of ten large-scale models, both land-surface models and global hydrological models, that participated in the model intercomparison project of WATCH (WaterMIP. For a selection of case study areas, we studied drought characteristics (number of droughts, duration, severity, drought propagation features (pooling, attenuation, lag, lengthening, and hydrological drought typology (classical rainfall deficit drought, rain-to-snow-season drought, wet-to-dry-season drought, cold snow season drought, warm snow season drought, composite drought.

    Drought characteristics simulated by large-scale models clearly reflected drought propagation; i.e. drought events became fewer and longer when moving through the hydrological cycle. However, more differentiation was expected between fast and slowly responding systems, with slowly responding systems having fewer and longer droughts in runoff than fast responding systems. This was not found using large-scale models. Drought propagation features were poorly reproduced by the large-scale models, because runoff reacted immediately to precipitation, in all case study areas. This fast reaction to precipitation, even in cold climates in winter and in semi-arid climates in summer, also greatly influenced the hydrological drought typology as identified by the large-scale models. In general, the large-scale models had the correct representation of drought types, but the percentages of occurrence had some important mismatches, e.g. an overestimation of classical rainfall deficit droughts, and an

  13. Short-term droughts forecast using Markov chain model in Victoria, Australia

    Science.gov (United States)

    Rahmat, Siti Nazahiyah; Jayasuriya, Niranjali; Bhuiyan, Muhammed A.

    2016-04-01

    A comprehensive risk management strategy for dealing with drought should include both short-term and long-term planning. The objective of this paper is to present an early warning method to forecast drought using the Standardised Precipitation Index (SPI) and a non-homogeneous Markov chain model. A model such as this is useful for short-term planning. The developed method has been used to forecast droughts at a number of meteorological monitoring stations that have been regionalised into six (6) homogenous clusters with similar drought characteristics based on SPI. The non-homogeneous Markov chain model was used to estimate drought probabilities and drought predictions up to 3 months ahead. The drought severity classes defined using the SPI were computed at a 12-month time scale. The drought probabilities and the predictions were computed for six clusters that depict similar drought characteristics in Victoria, Australia. Overall, the drought severity class predicted was quite similar for all the clusters, with the non-drought class probabilities ranging from 49 to 57 %. For all clusters, the near normal class had a probability of occurrence varying from 27 to 38 %. For the more moderate and severe classes, the probabilities ranged from 2 to 13 % and 3 to 1 %, respectively. The developed model predicted drought situations 1 month ahead reasonably well. However, 2 and 3 months ahead predictions should be used with caution until the models are developed further.

  14. Simulation of Change Trend of Drought in Shaanxi Province in Future Based on PRECIS Model

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    [Objective] The aim was to predict the change trend of drought in Shaanxi Province in future. [Method] Based on the regional climate model PRECIS from Hadley Climate Center, British Meteorological Bureau, taking precipitation anomaly percentage as assessment index, the change trend of drought in Shaanxi Province in reference years (1971-1990) was simulated, and the change trend of drought in Shaanxi Province from 2071 to 2100 was predicted. [Result] The simulated value of drought frequency in reference year...

  15. Evaluation of drought propagation in an ensemble mean of large-scale hydrological models

    Directory of Open Access Journals (Sweden)

    A. F. Van Loon

    2012-07-01

    Full Text Available Hydrological drought is increasingly studied using large-scale models. It is, however, not sure whether large-scale models reproduce the development of hydrological drought correctly. The pressing question is: how well do large-scale models simulate the propagation from meteorological to hydrological drought? To answer this question, we evaluated the simulation of drought propagation in an ensemble mean of ten large-scale models, both land-surface models and global hydrological models, that were part of the model intercomparison project of WATCH (WaterMIP. For a selection of case study areas, we studied drought characteristics (number of droughts, duration, severity, drought propagation features (pooling, attenuation, lag, lengthening, and hydrological drought typology (classical rainfall deficit drought, rain-to-snow-season drought, wet-to-dry-season drought, cold snow season drought, warm snow season drought, composite drought.

    Drought characteristics simulated by large-scale models clearly reflected drought propagation, i.e. drought events became less and longer when moving through the hydrological cycle. However, more differentiation was expected between fast and slowly responding systems, with slowly responding systems having less and longer droughts in runoff than fast responding systems. This was not found using large-scale models. Drought propagation features were poorly reproduced by the large-scale models, because runoff reacted immediately to precipitation, in all case study areas. This fast reaction to precipitation, even in cold climates in winter and in semi-arid climates in summer, also greatly influenced the hydrological drought typology as identified by the large-scale models. In general, the large-scale models had the correct representation of drought types, but the percentages of occurrence had some important mismatches, e.g. an overestimation of classical rainfall deficit droughts, and an

  16. Multivariate Statistical Modelling of Drought and Heat Wave Events

    Science.gov (United States)

    Manning, Colin; Widmann, Martin; Vrac, Mathieu; Maraun, Douglas; Bevaqua, Emanuele

    2016-04-01

    Multivariate Statistical Modelling of Drought and Heat Wave Events C. Manning1,2, M. Widmann1, M. Vrac2, D. Maraun3, E. Bevaqua2,3 1. School of Geography, Earth and Environmental Sciences, University of Birmingham, Edgbaston, Birmingham, UK 2. Laboratoire des Sciences du Climat et de l'Environnement, (LSCE-IPSL), Centre d'Etudes de Saclay, Gif-sur-Yvette, France 3. Wegener Center for Climate and Global Change, University of Graz, Brandhofgasse 5, 8010 Graz, Austria Compound extreme events are a combination of two or more contributing events which in themselves may not be extreme but through their joint occurrence produce an extreme impact. Compound events are noted in the latest IPCC report as an important type of extreme event that have been given little attention so far. As part of the CE:LLO project (Compound Events: muLtivariate statisticaL mOdelling) we are developing a multivariate statistical model to gain an understanding of the dependence structure of certain compound events. One focus of this project is on the interaction between drought and heat wave events. Soil moisture has both a local and non-local effect on the occurrence of heat waves where it strongly controls the latent heat flux affecting the transfer of sensible heat to the atmosphere. These processes can create a feedback whereby a heat wave maybe amplified or suppressed by the soil moisture preconditioning, and vice versa, the heat wave may in turn have an effect on soil conditions. An aim of this project is to capture this dependence in order to correctly describe the joint probabilities of these conditions and the resulting probability of their compound impact. We will show an application of Pair Copula Constructions (PCCs) to study the aforementioned compound event. PCCs allow in theory for the formulation of multivariate dependence structures in any dimension where the PCC is a decomposition of a multivariate distribution into a product of bivariate components modelled using copulas. A

  17. On the potential application of land surface models for drought monitoring in China

    Science.gov (United States)

    Zhang, Liang; Zhang, Huqiang; Zhang, Qiang; Li, Yaohui; Zhao, Jianhua

    2016-01-01

    The potential of using land surface models (LSMs) to monitor near-real-time drought has not been fully assessed in China yet. In this study, we analyze the performance of such a system with a land surface model (LSM) named the Australian Community Atmosphere Biosphere Land Exchange model (CABLE). The meteorological forcing datasets based on reanalysis products and corrected by observational data have been extended to near-real time for semi-operational trial. CABLE-simulated soil moisture (SM) anomalies are used to characterize drought spatial and temporal evolutions. One outstanding feature in our analysis is that with the same meteorological data, we have calculated a range of drought indices including Standardized Precipitation Index (SPI), Standardized Precipitation-Evapotranspiration Index (SPEI), Palmer Drought Severity Index (PDSI). We have assessed the similarity among these indices against observed SM over a number of regions in China. While precipitation is the dominant factor in the drought development, relationships between precipitation, evaporation, and soil moisture anomalies vary significantly under different climate regimes, resulting in different characteristics of droughts in China. The LSM-based trial system is further evaluated for the 1997/1998 drought in northern China and 2009/2010 drought in southwestern China. The system can capture the severities and temporal and spatial evolutions of these drought events well. The advantage of using a LSM-based drought monitoring system is further demonstrated by its potential to monitor other consequences of drought impacts in a more physically consistent manner.

  18. Optimization of Evaporative Demand Models for Seasonal Drought Forecasting

    Science.gov (United States)

    McEvoy, D.; Huntington, J. L.; Hobbins, M.

    2015-12-01

    Providing reliable seasonal drought forecasts continues to pose a major challenge for scientists, end-users, and the water resources and agricultural communities. Precipitation (Prcp) forecasts beyond weather time scales are largely unreliable, so exploring new avenues to improve seasonal drought prediction is necessary to move towards applications and decision-making based on seasonal forecasts. A recent study has shown that evaporative demand (E0) anomaly forecasts from the Climate Forecast System Version 2 (CFSv2) are consistently more skillful than Prcp anomaly forecasts during drought events over CONUS, and E0 drought forecasts may be particularly useful during the growing season in the farming belts of the central and Midwestern CONUS. For this recent study, we used CFSv2 reforecasts to assess the skill of E0 and of its individual drivers (temperature, humidity, wind speed, and solar radiation), using the American Society for Civil Engineers Standardized Reference Evapotranspiration (ET0) Equation. Moderate skill was found in ET0, temperature, and humidity, with lesser skill in solar radiation, and no skill in wind. Therefore, forecasts of E0 based on models with no wind or solar radiation inputs may prove to be more skillful than the ASCE ET0. For this presentation we evaluate CFSv2 E0 reforecasts (1982-2009) from three different E0 models: (1) ASCE ET0; (2) Hargreaves and Samani (ET-HS), which is estimated from maximum and minimum temperature alone; and (3) Valiantzas (ET-V), which is a modified version of the Penman method for use when wind speed data are not available (or of poor quality) and is driven only by temperature, humidity, and solar radiation. The University of Idaho's gridded meteorological data (METDATA) were used as observations to evaluate CFSv2 and also to determine if ET0, ET-HS, and ET-V identify similar historical drought periods. We focus specifically on CFSv2 lead times of one, two, and three months, and season one forecasts; which are

  19. Modeling physiological responses of soil microbes to drought (Invited)

    Science.gov (United States)

    Manzoni, S.; Katul, G. G.; Porporato, A. M.; Schaeffer, S. M.; Schimel, J.

    2013-12-01

    Biogeochemical models predict soil carbon (C) under varying environmental conditions, aiming to disentangle the effects of predicted changes in temperature and moisture regimes on C storage. While much work focuses on temperature sensitivity of decomposition, relatively less is known about decomposer responses to changes in soil moisture. Heterotrophic respiration is known to decline as soils become drier, but the underlying physiological mechanisms are not clear and rarely accounted for in models. In particular, we ask: what are the effects of different drought response strategies on C storage potential and the shape of the respiration-moisture relation? We have developed a process-based model to address these questions, including the main physiological responses thought to play a role under varying moisture conditions: i) dormancy, ii) patterns of extra-cellular enzyme production, and iii) osmoregulation. We show that these different drought response strategies play a major role in the long-term partitioning of soil C among stable and labile pools. In very dry conditions, microbes shifting to dormant state tend to favor long-term (steady state) accumulation of stable C at the expenses of microbial biomass, while increasing investment in enzymes leads to accumulation of dissolved organic C, which in turn may partly overcome the diffusion limitations imposed by dry soils. In contrast, entering a dormant state early during a dry down allows microbes to save C by respiring less (due to lowered active biomass), avoid C starvation when substrate diffusion breaks down, and use available C for growth and maintenance rather than osmoregulation. Hence, this strategy explains why little osmolytes are found in microbial biomass subjected to experimental drought. We conclude by highlighting how our results can be implemented in Earth System Models without excessively increasing their complexity.

  20. Implementing the Schoolwide Enrichment Model in Brazil

    Science.gov (United States)

    de Souza Fleith, Denise; Soriano de Alencar, Eunice M. L.

    2010-01-01

    The Schoolwide Enrichment Model (SEM) has been one of the most widely used models in the education of the gifted in Brazil. It has inspired the political and pedagogical project of the Centers of Activities of High Abilities/Giftedness recently implemented in 27 Brazilian states by the Ministry of Education. In this article, our experience in…

  1. Approaches to modeling landscape-scale drought-induced forest mortality

    Science.gov (United States)

    Gustafson, Eric J.; Shinneman, Douglas

    2015-01-01

    Drought stress is an important cause of tree mortality in forests, and drought-induced disturbance events are projected to become more common in the future due to climate change. Landscape Disturbance and Succession Models (LDSM) are becoming widely used to project climate change impacts on forests, including potential interactions with natural and anthropogenic disturbances, and to explore the efficacy of alternative management actions to mitigate negative consequences of global changes on forests and ecosystem services. Recent studies incorporating drought-mortality effects into LDSMs have projected significant potential changes in forest composition and carbon storage, largely due to differential impacts of drought on tree species and interactions with other disturbance agents. In this chapter, we review how drought affects forest ecosystems and the different ways drought effects have been modeled (both spatially and aspatially) in the past. Building on those efforts, we describe several approaches to modeling drought effects in LDSMs, discuss advantages and shortcomings of each, and include two case studies for illustration. The first approach features the use of empirically derived relationships between measures of drought and the loss of tree biomass to drought-induced mortality. The second uses deterministic rules of species mortality for given drought events to project changes in species composition and forest distribution. A third approach is more mechanistic, simulating growth reductions and death caused by water stress. Because modeling of drought effects in LDSMs is still in its infancy, and because drought is expected to play an increasingly important role in forest health, further development of modeling drought-forest dynamics is urgently needed.

  2. Investigating Differences between Modeled Historical and Station Calculated Drought

    Science.gov (United States)

    With growing concern over increased frequency and intensity of extreme climate events, there is an imperative need to investigate drought under different future scenarios for the contiguous U.S. To assess future drought relative to a historical baseline, drought occurrence (numbe...

  3. Space-time modeling of catchment scale drought characteristics

    NARCIS (Netherlands)

    Tallaksen, L.; Hisdal, H.; Lanen, van H.A.J.

    2009-01-01

    Drought may affect all components of the water cycle and covers commonly a large part of the catchment area. This paper examines drought propagation at the catchment scale using spatially aggregated drought characteristics and illustrates the importance of catchment processes in modifying the drough

  4. Multi-basin, Multi-sector Drought Economic Impact Model in Python: Development and Applications

    Science.gov (United States)

    Gutenson, J. L.; Zhu, L.; Ernest, A. N. S.; Oubeidillah, A.; Bearden, B.; Johnson, T. G.

    2015-12-01

    Drought is one of the most economically disastrous natural hazards, one whose impacts are exacerbated by the lack of abrupt onset and offset that define tornados and hurricanes. In the United States, about 30 billion dollars losses is caused by drought in 2012, resulting in widespread economic impacts for societies, industries, agriculture, and recreation. And in California, the drought cost statewide economic losses about 2.2 billion, with a total loss of 17,100 seasonal and part-time jobs. Driven by a variety of factors including climate change, population growth, increased water demands, alteration to land cover, drought occurs widely all over the world. Drought economic consequence assessment tool are greatly needed to allow decision makers and stakeholders to anticipate and manage effectively. In this study, current drought economic impact modeling methods were reviewed. Most of these models only deal with the impact in the agricultural sector with a focus on a single basin; few of these models analyze long term impact. However, drought impacts are rarely restricted to basin boundaries, and cascading economic impacts are likely to be significant. A holistic approach to multi-basin, multi-sector drought economic impact assessment is needed.In this work, we developed a new model for drought economic impact assessment, Drought Economic Impact Model in Python (PyDEM). This model classified all business establishments into thirteen categories based on NAICS, and using a continuous dynamic social accounting matrix approach, coupled with calculation of the indirect consequences for the local and regional economies and the various resilience. In addition, Environmental Policy Integrated Climate model was combined for analyzing drought caused soil erosion together with agriculture production, and then the long term impacts of drought were achieved. A visible output of this model was presented in GIS. In this presentation, Choctawhatchee-Pea-Yellow River Basins, Alabama

  5. Towards Remotely Sensed Composite Global Drought Risk Modelling

    Science.gov (United States)

    Dercas, Nicholas; Dalezios, Nicolas

    2015-04-01

    Drought is a multi-faceted issue and requires a multi-faceted assessment. Droughts may have the origin on precipitation deficits, which sequentially and by considering different time and space scales may impact soil moisture, plant wilting, stream flow, wildfire, ground water levels, famine and social impacts. There is a need to monitor drought even at a global scale. Key variables for monitoring drought include climate data, soil moisture, stream flow, ground water, reservoir and lake levels, snow pack, short-medium-long range forecasts, vegetation health and fire danger. However, there is no single definition of drought and there are different drought indicators and indices even for each drought type. There are already four operational global drought risk monitoring systems, namely the U.S. Drought Monitor, the European Drought Observatory (EDO), the African and the Australian systems, respectively. These systems require further research to improve the level of accuracy, the time and space scales, to consider all types of drought and to achieve operational efficiency, eventually. This paper attempts to contribute to the above mentioned objectives. Based on a similar general methodology, the multi-indicator approach is considered. This has resulted from previous research in the Mediterranean region, an agriculturally vulnerable region, using several drought indices separately, namely RDI and VHI. The proposed scheme attempts to consider different space scaling based on agroclimatic zoning through remotely sensed techniques and several indices. Needless to say, the agroclimatic potential of agricultural areas has to be assessed in order to achieve sustainable and efficient use of natural resources in combination with production maximization. Similarly, the time scale is also considered by addressing drought-related impacts affected by precipitation deficits on time scales ranging from a few days to a few months, such as non-irrigated agriculture, topsoil moisture

  6. Modeling the relationship between climate oscillations and drought by a multivariate GARCH model

    Science.gov (United States)

    Modarres, R.; Ouarda, T. B. M. J.

    2014-01-01

    Typical multivariate time series models may exhibit comovement in mean but not in variance of hydrologic and climatic variables. This paper introduces multivariate generalized autoregressive conditional heteroscedasticity (GARCH) models to capture the comovement of the variance or the conditional covariance between two hydroclimatic time series. The diagonal vectorized and Baba-Engle-Kroft-Kroner models are developed to evaluate the covariance between drought and two atmospheric circulations, Southern Oscillation Index (SOI) and North Atlantic Oscillation (NAO) time series during 1954-2000. The univariate generalized autoregressive conditional heteroscedasticity model indicates a strong persistency level in conditional variance for NAO and a moderate persistency level for SOI. The conditional variance of short-term drought index indicates low level of persistency, while the long-term index drought indicates high level of persistency in conditional variance. The estimated conditional covariance between drought and atmospheric indices is shown to be weak and negative. It is also observed that the covariance between drought and atmospheric indices is largely dependent on short-run variance of atmospheric indices rather than their long-run variance. The nonlinearity and stationarity tests show that the conditional covariances are nonlinear but stationary. However, the degree of nonlinearity is higher for the covariance between long-term drought and atmospheric indices. It is also observed that the nonlinearity of NAO is higher than that for SOI, in contrast to the stationarity which is stronger for SOI time series.

  7. Evaluation of drought propagation in an ensemble mean of large-scale hydrological models

    NARCIS (Netherlands)

    Loon, van A.F.; Huijgevoort, van M.H.J.; Lanen, van H.A.J.

    2012-01-01

    Hydrological drought is increasingly studied using large-scale models. It is, however, not sure whether large-scale models reproduce the development of hydrological drought correctly. The pressing question is how well do large-scale models simulate the propagation from meteorological to hydrological

  8. Drought-associated changes in climate and their relevance for ecosystem experiments and models

    Directory of Open Access Journals (Sweden)

    H. J. De Boeck

    2011-05-01

    Full Text Available Drought periods can have important impacts on plant productivity and ecosystem functioning, but climatic conditions other than the lack of precipitation during droughts have never been quantified and have therefore not been considered explicitly in both experimental and modeling studies. Here, we identify which climatic characteristics deviate from normal during droughts and how these deviations could affect plant responses. Analysis of 609 years of daily data from nine Western European meteorological stations reveals that droughts in the studied region are consistently associated with more sunshine (+45 %, increased mean (+1.6 °C and maximum (+2.8 °C air temperatures and vapour pressure deficits that were 51 % higher than under normal conditions. These deviations from normal increase significantly as droughts progress. Using the process-model ORCHIDEE, we simulated droughts consistent with the results of the dataset analysis and compared water and carbon exchange of three different vegetation types during such natural droughts and droughts in which only the precipitation was affected. The comparison revealed contrasting responses: carbon loss was higher under natural drought in grasslands, while increased carbon uptake was found especially in decidious forests. This difference was attributed to better access to water reserves in forest ecosystems which prevented drought stress. This demonstrates that the warmer and sunnier conditions naturally associated with droughts can either improve growth or aggravate drought-related stress, depending on water reserves. As the impacts of including or excluding climatic parameters that correlate with drought are substantial, we propose that both experimental and modeling efforts should take into account other environmental factors than merely precipitation.

  9. Drought-associated changes in climate and their relevance for ecosystem experiments and models

    Directory of Open Access Journals (Sweden)

    H. J. De Boeck

    2011-01-01

    Full Text Available Drought periods can have important impacts on plant productivity and ecosystem functioning, but climatic conditions other than the lack of precipitation during droughts have never been quantified and have therefore not been considered explicitly in both experimental and modeling studies. Here, we identify which climatic characteristics deviate from normal during droughts and how these deviations could affect plant responses. Analysis of 609 years of daily data from nine Western European meteorological datasets reveals that droughts in the studied region are consistently associated with more sunshine (+45%, increased mean (+1.6 °C and maximum (+2.8 °C air temperatures and vapour pressure deficits that were 51% higher than under normal conditions. These deviations from normal increase significantly as droughts progress. Using the process-model ORCHIDEE, we simulated droughts consistent with the results of the dataset analysis and compared water and carbon exchange of three different vegetation types during such natural droughts and droughts in which only the precipitation was affected. The comparison revealed contrasting responses: carbon loss was higher under natural drought in grasslands, while increased carbon uptake was found especially in decidious forests. This difference was attributed to better access to water reserves in forest ecosystems which prevented drought stress. This demonstrates that the warmer and sunnier conditions naturally associated with droughts can either improve growth or aggravate drought-related stress, depending on water reserves. As the impacts of including or excluding climatic parameters that correlate with drought are substantial, we propose that both experimental and modeling efforts should take into account other environmental factors than merely precipitation.

  10. Effects of Severe Floods and Droughts on Wildlife of the Pantanal Wetland (Brazil)-A Review.

    Science.gov (United States)

    Alho, Cleber J R; Silva, João S V

    2012-10-18

    Flooding throughout the Pantanal is seasonal. The complex vegetative cover and high seasonal productivity support a diverse and abundant fauna. A gradient in flood level supports a range of major habitats in a complex mosaic with annual seasonality. The rivers and streams are lined with gallery forests, and other arboreal habitats exist in the more elevated areas. The remainder is either grasslands or seasonally flooded grasslands. The regional flora and fauna are adapted to annual water fluctuation. However, an inter-annual series of higher or lower rainfalls has caused either severe floods or drastic dry seasons. Large scale climate phenomena such as greenhouse gases, El Niño and La Niña influence the seasonality of floods and droughts in the Pantanal. Knowledge of severe floods and droughts, which characterize natural disasters, is fundamental for wildlife management and nature conservation of the Pantanal. Plants and wild animals, for example, are affected by tree mortality in riparian forest after extreme flooding, with consequent habitat modification for wild animals. In addition, human activities are also affected since cattle ranching and ecotourism are economically important in the region, and when seasons with unusual floods or droughts occur, areas with human settlements are impacted.

  11. Drought Impacts on Reservoir Storage and Hydro-electricity Production in Southeastern Brazil

    Science.gov (United States)

    Scanlon, B. R.; Melo, D. D.; Yin, L.; Wendland, E.

    2015-12-01

    Brazilian hydroelectric plants (HP) generate ~85% of the total electricity in the country (138 GW). More than half of the number largest reservoirs are located in the Southeast/Midwest region, where ~50% of the population (~100 million) lives. The 2014 drought raised several questions about the resilience of the water sources when several urban centers, including Brazilian's largest metropolis (São Paulo, 20 million people), had their water supply threatened. Such drought also affected reservoirs of hydroelectric plants. This study assesses how the storage and, thus the electricity generation, in 14 of the largest reservoirs were affected by drought events within the past 20 years. We computed the Standardized Precipitation Index (SPI) to identify rainfall anomalies throughout the analyzed period. To evaluate the impacts on surface water, we assessed the changes in total (surface+ subsurface) runoff and soil moisture from Global Land Data Assimilation System (GLDAS) and in Total Water Storage (TWS) from Gravity Recovery and Climate Experiment (GRACE) satellite data. We evaluated the anomalies and significance of the changes in reservoir storage (RS) and electricity generation. The results show that severe dry years (-1.5 resilience in the future.

  12. Effects of Severe Floods and Droughts on Wildlife of the Pantanal Wetland (Brazil)-A Review.

    Science.gov (United States)

    Alho, Cleber J R; Silva, João S V

    2012-01-01

    Flooding throughout the Pantanal is seasonal. The complex vegetative cover and high seasonal productivity support a diverse and abundant fauna. A gradient in flood level supports a range of major habitats in a complex mosaic with annual seasonality. The rivers and streams are lined with gallery forests, and other arboreal habitats exist in the more elevated areas. The remainder is either grasslands or seasonally flooded grasslands. The regional flora and fauna are adapted to annual water fluctuation. However, an inter-annual series of higher or lower rainfalls has caused either severe floods or drastic dry seasons. Large scale climate phenomena such as greenhouse gases, El Niño and La Niña influence the seasonality of floods and droughts in the Pantanal. Knowledge of severe floods and droughts, which characterize natural disasters, is fundamental for wildlife management and nature conservation of the Pantanal. Plants and wild animals, for example, are affected by tree mortality in riparian forest after extreme flooding, with consequent habitat modification for wild animals. In addition, human activities are also affected since cattle ranching and ecotourism are economically important in the region, and when seasons with unusual floods or droughts occur, areas with human settlements are impacted. PMID:26487165

  13. Prediction of Drought Risk Based on the WRF Model in Yunnan Province of China

    Directory of Open Access Journals (Sweden)

    Chunhong Zhao

    2013-01-01

    Full Text Available Yunnan province is the core region of the drought in the Southwest China, which makes the region become the hot spot in the meteorological research. However, among the various influencing factors of the drought in Yunnan province, the influence of the land use/cover change (LUCC on the drought has not been quantitatively analyzed. The LUCC in recent decades was first quantitatively analyzed in this study. Given the fact that severe drought in Yunnan province is mainly due to much-less-than-normal precipitation and much-warmer-than-normal surface temperature, this study focused on the future spatiotemporal heterogeneity of the temperature and precipitation, which have great impacts on the drought. Finally, the influencing factors of drought in Yunnan province were simulated with the Weather Research and Forecasting (WRF model, and the risk of drought was spatially analyzed with the meteorological drought composite index. The results indicate that the large-area forest plays a more important role in alleviating the risk of drought than other vegetation types do. Besides, the changes of the landscape structure resulting from the urban expansion play a significant role in intensifying the risk of drought.

  14. A geospatial suitability model for drought-tolerant switchgrass

    Science.gov (United States)

    Lewis, S. M.; Kelly, M.

    2011-12-01

    A perennial grass native to the North America, switchgrass (Panicum virgatum) has been targeted by the USDA as a model mass bioenergy crop to replace petroleum energy products and meet policy demands. Although highly water use efficient, as a warm-season crop, switchgrass requires a significant amount of water during the growing season (April -September). However, locations that have highly reliable water availability are also ideal for profitable food crops (e.g. corn and soy growing regions) and food competition is a significant concern in regards to biofuel crops being grown on productive agricultural lands. Drier, marginal lands (lands on which normal agricultural crops are difficult to cultivate) are therefore potentially ideal locations to grow biofuel crops to ensure that food competition is not an issue. Genetics scientists at UC Davis are in the process of developing a modified variety of switchgrass that can withstand extended periods of drought while not substantially affecting overall yield. As this product is being developed, it is important to identify the potential geographical niche for this new drought-tolerant variety of switchgrass. This project introduces a geospatial approach that utilizes both physical and economic variables to identify ideal geographic locations for this innovative crop.

  15. Identifying the role of typhoons as drought busters in South Korea based on hidden Markov chain models

    Science.gov (United States)

    Yoo, Jiyoung; Kwon, Hyun-Han; So, Byung-Jin; Rajagopalan, Balaji; Kim, Tae-Woong

    2015-04-01

    This study proposed a hidden Markov chain model-based drought analysis (HMM-DA) tool to understand the beginning and ending of meteorological drought and to further characterize typhoon-induced drought busters (TDB) by exploring spatiotemporal drought patterns in South Korea. It was found that typhoons have played a dominant role in ending drought events (EDE) during the typhoon season (July-September) over the last four decades (1974-2013). The percentage of EDEs terminated by TDBs was about 43-90% mainly along coastal regions in South Korea. Furthermore, the TDBs, mainly during summer, have a positive role in managing extreme droughts during the subsequent autumn and spring seasons. The HMM-DA models the temporal dependencies between drought states using Markov chain, consequently capturing the dependencies between droughts and typhoons well, thus, enabling a better performance in modeling spatiotemporal drought attributes compared to traditional methods.

  16. 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.

  17. Characterising and quantifying vegetative drought in East Africa using fuzzy modelling and NDVI data

    NARCIS (Netherlands)

    Rulinda, Coco M.; Dilo, Arta; Bijker, Wietske; Stein, Alfred

    2012-01-01

    This study aims at improving the characterisation and quantification of vegetative drought as a vague spatial phenomenon. 10-day NOAA-AVHRR NDVI images of East Africa from September 2005 to April 2006 are used. Vegetative drought is characterised using a membership function to model the gradual tran

  18. Differential effects of extreme drought on production and respiration: synthesis and modeling analysis

    Directory of Open Access Journals (Sweden)

    Z. Shi

    2013-10-01

    Full Text Available Extremes in climate may severely impact ecosystem structure and function, with both the magnitude and rate of response differing among ecosystem types and processes. We conducted a modeling analysis of the effects of extreme drought on two key ecosystem processes, production and respiration, and to provide broader context we complemented this with a synthesis of published results across multiple ecosystems. The synthesis indicated that across a broad range of biomes gross primary production (GPP generally was more sensitive to extreme drought (defined as proportional reduction relative to average rainfall periods than was ecosystem respiration (ER. Furthermore, this differential sensitivity between production and respiration increased as drought severity increased. The modeling analysis was designed to better understand the mechanisms underlying this pattern and focused on four grassland sites arrayed across the Great Plains, USA. Model results consistently showed that net primary productivity (NPP was reduced more than heterotrophic respiration (Rh by extreme drought (i.e., 67% reduction in annual ambient rainfall at all four study sites. The sensitivity of NPP to drought was directly attributable to rainfall amount, whereas sensitivity of Rh to drought was driven by both soil drying and a drought-induced reduction in soil carbon (C content, a much slower process. However, differences in reductions in NPP and Rh diminished as extreme drought continued due to a gradual decline in the soil C pool leading to further reductions in Rh. We also varied the way in which drought was imposed in the modeling analysis, either as reductions in rainfall event size (ESR or by reducing rainfall event number (REN. Modeled NPP and Rh decreased more by ESR than REN at the two relatively mesic sites but less so at the two xeric sites. Our findings suggest that responses of production and respiration differ in magnitude, occur on different timescales and are

  19. Do land surface models need to include differential plant species responses to drought? Examining model predictions across a mesic-xeric gradient in Europe

    OpenAIRE

    M. G. De Kauwe; Zhou, S.-X.; B. E. Medlyn; Pitman, A.J.; Wang, Y.-P.; R. A. Duursma; Prentice, I. C.

    2015-01-01

    Future climate change has the potential to increase drought in many regions of the globe, making it essential that land surface models (LSMs) used in coupled climate models realistically capture the drought responses of vegetation. Recent data syntheses show that drought sensitivity varies considerably among plants from different climate zones, but state-of-the-art LSMs currently assume the same drought sensitivity for all vegetation. We tested whether variable drought sensi...

  20. On the spatio-temporal analysis of hydrological droughts from global hydrological models

    Directory of Open Access Journals (Sweden)

    G. A. Corzo Perez

    2011-09-01

    Full Text Available The recent concerns for world-wide extreme events related to climate change have motivated the development of large scale models that simulate the global water cycle. In this context, analysis of hydrological extremes is important and requires the adaptation of identification methods used for river basin models. This paper presents two methodologies that extend the tools to analyze spatio-temporal drought development and characteristics using large scale gridded time series of hydrometeorological data. The methodologies are classified as non-contiguous and contiguous drought area analyses (i.e. NCDA and CDA. The NCDA presents time series of percentages of areas in drought at the global scale and for pre-defined regions of known hydroclimatology. The CDA is introduced as a complementary method that generates information on the spatial coherence of drought events at the global scale. Spatial drought events are found through CDA by clustering patterns (contiguous areas. In this study the global hydrological model WaterGAP was used to illustrate the methodology development. Global gridded time series of subsurface runoff (resolution 0.5° simulated with the WaterGAP model from land points were used. The NCDA and CDA were developed to identify drought events in runoff. The percentages of area in drought calculated with both methods show complementary information on the spatial and temporal events for the last decades of the 20th century. The NCDA provides relevant information on the average number of droughts, duration and severity (deficit volume for pre-defined regions (globe, 2 selected hydroclimatic regions. Additionally, the CDA provides information on the number of spatially linked areas in drought, maximum spatial event and their geographic location on the globe. Some results capture the overall spatio-temporal drought extremes over the last decades of the 20th century. Events like the El Niño Southern Oscillation (ENSO in South America and

  1. Use of Crop Models in Assessment of Soil Drought

    Directory of Open Access Journals (Sweden)

    Milada Stastna

    2007-03-01

    Full Text Available The aims of the study were to apply, test and to present the ability of the deterministic simulation models SIMWASER and CERES-Wheat computing soil-water balance components, percolation losses, ground water recharge and capillary rise. Two case studies for the assessment of percolation losses from irrigated carrots to deep groundwater at Obersiebenbrunn in the Marchfeld (Austria and ground water recharge and capillary rise from shallow groundwater in grass lysimeters at Berlin-Dahlem (Germany together with two test sites with similar climatic conditions and soil water storage potential but with (Grossenzesdorf, Austria and without (Zabcice, Czech Republic groundwater impact in a semi-arid agricultural area in central Europe were chosen. At Obersiebenbrunn, simulated percolation and evapotranspiration were 183 and 629 mm, while the respective measured values amounted to 198 and 635 mm. Up to 42% (194 mm of evapotranspiration was provided by groundwater at s Grossenzesdorf and only 126 mm was used for the worst case comparing to observed data. Th ese results showed both models as proper applicable tools to demonstrate crop – soil – water relations. However, the availability and management of soil water reserves will remain important, especially when extreme events such as droughts occur more frequently and annual soil and groundwater recharge decrease.

  2. Non-linear effects of drought under shade: reconciling physiological and ecological models in plant communities.

    Science.gov (United States)

    Holmgren, Milena; Gómez-Aparicio, Lorena; Quero, José Luis; Valladares, Fernando

    2012-06-01

    The combined effects of shade and drought on plant performance and the implications for species interactions are highly debated in plant ecology. Empirical evidence for positive and negative effects of shade on the performance of plants under dry conditions supports two contrasting theoretical models about the role of shade under dry conditions: the trade-off and the facilitation hypotheses. We performed a meta-analysis of field and greenhouse studies evaluating the effects of drought at two or more irradiance levels on nine response variables describing plant physiological condition, growth, and survival. We explored differences in plant response across plant functional types, ecosystem types and methodological approaches. The data were best fit using quadratic models indicating a humped-back shape response to drought along an irradiance gradient for survival, whole plant biomass, maximum photosynthetic capacity, stomatal conductance and maximal photochemical efficiency. Drought effects were ameliorated at intermediate irradiance, becoming more severe at higher or lower light levels. This general pattern was maintained when controlling for potential variations in the strength of the drought treatment among light levels. Our quantitative meta-analysis indicates that dense shade ameliorates drought especially among drought-intolerant and shade-tolerant species. Wet tropical species showed larger negative effects of drought with increasing irradiance than semiarid and cold temperate species. Non-linear responses to irradiance were stronger under field conditions than under controlled greenhouse conditions. Non-linear responses to drought along the irradiance gradient reconciliate opposing views in plant ecology, indicating that facilitation is more likely within certain range of environmental conditions, fading under deep shade, especially for drought-tolerant species. PMID:22083284

  3. Forecasting European Droughts using the North American Multi-Model Ensemble (NMME)

    Science.gov (United States)

    Thober, Stephan; Kumar, Rohini; Samaniego, Luis; Sheffield, Justin; Schäfer, David; Mai, Juliane

    2015-04-01

    Soil moisture droughts have the potential to diminish crop yields causing economic damage or even threatening the livelihood of societies. State-of-the-art drought forecasting systems incorporate seasonal meteorological forecasts to estimate future drought conditions. Meteorological forecasting skill (in particular that of precipitation), however, is limited to a few weeks because of the chaotic behaviour of the atmosphere. One of the most important challenges in drought forecasting is to understand how the uncertainty in the atmospheric forcings (e.g., precipitation and temperature) is further propagated into hydrologic variables such as soil moisture. The North American Multi-Model Ensemble (NMME) provides the latest collection of a multi-institutional seasonal forecasting ensemble for precipitation and temperature. In this study, we analyse the skill of NMME forecasts for predicting European drought events. The monthly NMME forecasts are downscaled to daily values to force the mesoscale hydrological model (mHM). The mHM soil moisture forecasts obtained with the forcings of the dynamical models are then compared against those obtained with the Ensemble Streamflow Prediction (ESP) approach. ESP recombines historical meteorological forcings to create a new ensemble forecast. Both forecasts are compared against reference soil moisture conditions obtained using observation based meteorological forcings. The study is conducted for the period from 1982 to 2009 and covers a large part of the Pan-European domain (10°W to 40°E and 35°N to 55°N). Results indicate that NMME forecasts are better at predicting the reference soil moisture variability as compared to ESP. For example, NMME explains 50% of the variability in contrast to only 31% by ESP at a six-month lead time. The Equitable Threat Skill Score (ETS), which combines the hit and false alarm rates, is analysed for drought events using a 0.2 threshold of a soil moisture percentile index. On average, the NMME

  4. Anatomy of a local-scale drought: Application of assimilated remote sensing products, crop model, and statistical methods to an agricultural drought study

    Science.gov (United States)

    Mishra, Ashok K.; Ines, Amor V. M.; Das, Narendra N.; Prakash Khedun, C.; Singh, Vijay P.; Sivakumar, Bellie; Hansen, James W.

    2015-07-01

    Drought is of global concern for society but it originates as a local problem. It has a significant impact on water quantity and quality and influences food, water, and energy security. The consequences of drought vary in space and time, from the local scale (e.g. county level) to regional scale (e.g. state or country level) to global scale. Within the regional scale, there are multiple socio-economic impacts (i.e., agriculture, drinking water supply, and stream health) occurring individually or in combination at local scales, either in clusters or scattered. Even though the application of aggregated drought information at the regional level has been useful in drought management, the latter can be further improved by evaluating the structure and evolution of a drought at the local scale. This study addresses a local-scale agricultural drought anatomy in Story County in Iowa, USA. This complex problem was evaluated using assimilated AMSR-E soil moisture and MODIS-LAI data into a crop model to generate surface and sub-surface drought indices to explore the anatomy of an agricultural drought. Quantification of moisture supply in the root zone remains a gray area in research community, this challenge can be partly overcome by incorporating assimilation of soil moisture and leaf area index into crop modeling framework for agricultural drought quantification, as it performs better in simulating crop yield. It was noted that the persistence of subsurface droughts is in general higher than surface droughts, which can potentially improve forecast accuracy. It was found that both surface and subsurface droughts have an impact on crop yields, albeit with different magnitudes, however, the total water available in the soil profile seemed to have a greater impact on the yield. Further, agricultural drought should not be treated equal for all crops, and it should be calculated based on the root zone depth rather than a fixed soil layer depth. We envisaged that the results of

  5. Future discharge drought across climate regions around the world modelled with a synthetic hydrological modelling approach forced by three general circulation models

    Science.gov (United States)

    Wanders, N.; Van Lanen, H. A. J.

    2015-03-01

    Hydrological drought characteristics (drought in groundwater and streamflow) likely will change in the 21st century as a result of climate change. The magnitude and directionality of these changes and their dependency on climatology and catchment characteristics, however, is uncertain. In this study a conceptual hydrological model was forced by downscaled and bias-corrected outcome from three general circulation models for the SRES A2 emission scenario (GCM forced models), and the WATCH Forcing Data set (reference model). The threshold level method was applied to investigate drought occurrence, duration and severity. Results for the control period (1971-2000) show that the drought characteristics of each GCM forced model reasonably agree with the reference model for most of the climate types, suggesting that the climate models' results after post-processing produce realistic outcomes for global drought analyses. For the near future (2021-2050) and far future (2071-2100) the GCM forced models show a decrease in drought occurrence for all major climates around the world and increase of both average drought duration and deficit volume of the remaining drought events. The largest decrease in hydrological drought occurrence is expected in cold (D) climates where global warming results in a decreased length of the snow season and an increased precipitation. In the dry (B) climates the smallest decrease in drought occurrence is expected to occur, which probably will lead to even more severe water scarcity. However, in the extreme climate regions (desert and polar), the drought analysis for the control period showed that projections of hydrological drought characteristics are most uncertain. On a global scale the increase in hydrological drought duration and severity in multiple regions will lead to a higher impact of drought events, which should motivate water resource managers to timely anticipate the increased risk of more severe drought in groundwater and streamflow

  6. On the spatio-temporal analysis of hydrological droughts from global hydrological models

    Directory of Open Access Journals (Sweden)

    G. A. Corzo Perez

    2011-01-01

    Full Text Available The recent concerns for world-wide extreme events related to climate change phenomena have motivated the development of large scale models that simulate the global water cycle. In this context, analyses of extremes is an important topic that requires the adaptation of methods used for river basin and regional scale models. This paper presents two methodologies that extend the tools to analyze spatio-temporal drought development and characteristics using large scale gridded time series of hydrometeorological data. The methodologies are distinguished and defined as non-contiguous and contiguous drought area analyses (i.e. NCDA and CDA. The NCDA presents time series of percentages of areas in drought at the global scale and for pre-defined regions of known hydroclimatology. The CDA is introduced as a complementary method that generates information on the spatial coherence of drought events at the global scale. Spatial drought events are found through CDA by clustering patterns (contiguous areas. In this study the global hydrological model WaterGAP was used to illustrate the methodology development. Global gridded time series (resolution 0.5° simulated with the WaterGAP model from land points were used. The NCDA and CDA were applied to identify drought events in subsurface runoff. The percentages of area in drought calculated with both methods show complementary information on the spatial and temporal events for the last decades of the 20th century. The NCDA provides relevant information on the average number of droughts, duration and severity (deficit volume for pre-defined regions (globe, 2 selected climate regions. Additionally, the CDA provides information on the number of spatially linked areas in drought as well as their geographic location on the globe. An explorative validation process shows that the NCDA results capture the overall spatio-temporal drought extremes over the last decades of the 20th century. Events like the El Niño Southern

  7. Simulating the link between ENSO and summer drought in Southern Africa using regional climate models

    Science.gov (United States)

    Meque, Arlindo; Abiodun, Babatunde J.

    2015-04-01

    This study evaluates the capability of regional climate models (RCMs) in simulating the link between El Niño Southern Oscillation (ENSO) and Southern African droughts. It uses the Standardized Precipitation-Evapotranspiration Index (SPEI, computed using rainfall and temperature data) to identify 3-month drought over Southern Africa, and compares the observed and simulated correlation between ENSO and SPEI. The observation data are from the Climate Research Unit, while the simulation data are from ten RCMs (ARPEGE, CCLM, HIRHAM, RACMO, REMO, PRECIS, RegCM3, RCA, WRF, and CRCM) that participated in the regional climate downscaling experiment (CORDEX) project. The study analysed the rainy season (December-February) data for 19 years (1989-2008). The results show a strong link between ENSO and droughts (SPEI) over Southern Africa. The link is owing to the influence of ENSO on both rainfall and temperature fields, but the correlation between ENSO and temperature is stronger than the correlation between ENSO and rainfall. Hence, using only rainfall to monitor droughts in Southern Africa may underestimate the influence of ENSO on the droughts. Only few CORDEX RCMs simulate the influence of ENSO on Southern African drought as observed. In this regard, the ARPEGE model shows the best simulation, while CRCM shows the worst. The different in the performance may be due to their lateral boundary conditions. The RCA-simulated link between ENSO and Southern African droughts is sensitive to the global dataset used as the lateral boundary conditions. In some cases, using RCA to downscale global circulation models (GCM) simulations adds value to the simulated link between ENSO and the droughts, but in other cases the downscaling adds no value to the link. The added value of RCA to the simulated link decreases as the capability of the GCM to simulate the link increases. This study suggests that downscaling GCM simulations with RCMs over Southern Africa may improve or depreciate the

  8. Predicting Historical Droughts in the US With a Multi-model Seasonal Hydrologic Prediction System

    Science.gov (United States)

    Luo, L.; Wood, E.; Sheffield, J.; Li, H.

    2008-12-01

    Droughts are as much a part of weather and climate extremes as floods, hurricanes and tornadoes are, but they are the most costly extremes among all natural disasters in the U.S. The estimated annual direct losses to the U.S economy due to droughts are about 6-8 billion, with the drought of 1988 estimated to have damages over $39 billion. Having a seasonal drought prediction system that can accurately predict the onset, development and recovery of drought episodes will significantly help to reduce the loss due to drought. In this study, a seasonal hydrologic ensemble prediction system developed for the eastern United States is used to predict historical droughts in the US retrospectively. The system uses a hydrologic model (i.e., the Variable Infiltration Capacity model) as the central element for producing ensemble predictions of soil moisture, snow, and streamflow with lead times up to six months. One unique feature of this system is in the method for generating ensemble atmospheric forcings for the forecast period. It merges seasonal climate forecasts from multiple climate models with observed climatology in a Bayesian framework, such that the uncertainties related to the atmospheric forcings can be better quantified while the signals from individual models are combined. Simultaneously, climate model forecasts are downscaled to an appropriate spatial scale for hydrologic predictions. When generating daily meteorological forcing, the system uses the rank structures of selected historical forcing records to ensure reasonable weather patterns in space and time. The system is applied to different regions in the US to predict historical drought episodes. These forecasts use seasonal climate forecast from a combination of the NCEP CFS and seven climate models in the European Union's Development of a European Multimodel Ensemble System for Seasonal to-Interannual Prediction (CFS+DEMETER). This study validates the approach of using seasonal climate predictions from

  9. Evidence and modeling study of droughts in China during 4 - 2 ka BP

    Institute of Scientific and Technical Information of China (English)

    WANG ShaoWu; HUANG JianBin; WEN XinYu; ZHU JinHong

    2008-01-01

    Four periods with predominated droughts are identified in 4-2 ka BP according to documentary data, namely 3.6-3.5, 3.1-3.0, 2.8-2.7, and 2.45-2.35 ka BP. Palaeo-environmental data indicated that droughts were predominated in 4-2 ka BP in the south of Northeast China, Inner-Mongolia, east of Qinghai-Tibetan Plateau, and South China. Modeling study shows that precession may be responsible for the occurrence of droughts in 4-2 ka BP, integrating the GCM with forcing of insolation.

  10. An observation-modelling framework to distinguish between water scarcity and drought

    Science.gov (United States)

    Van Loon, A. F.; Van Lanen, H. A. J.

    2012-04-01

    Drought and water scarcity are keywords for river basin managers in water-stressed regions like Africa, Asia and the Mediterranean Basin. Unfortunately, these terms are often misused. They refer to quite different phenomena. 'Drought' is a natural hazard, which is caused by climatic processes and their intrinsic variability, and cannot be prevented by short-term, local water management. 'Water scarcity' refers to the long-term unsustainable use of water resources and is a process that water managers can influence. The interrelationships between drought and water scarcity, however, are complex. In regions with low water availability and high human activity, water scarcity situations are common and can be exacerbated by drought events. The worst situation is a multi-year drought in a (semi )arid region with high demand for water. In monitoring the hydrological system for water management purposes, it is difficult (but essential) to determine which part of the signal is caused by water scarcity (human induced) and which part by drought (natural). So the urgent question for many water managers is: how to distinguish between water scarcity and drought? In this paper, we use a case study in the Upper-Guadiana catchment in Spain to demonstrate the use of an observation-modelling framework for distinguishing between water scarcity and drought. We will discuss the more generic aspects of such a framework, which is in principal applicable worldwide. Observation-modelling frameworks should help water managers in water-stressed regions like the Mediterranean to combat water scarcity, and to better adapt to drought by decreasing their vulnerability.

  11. Tolerance of canola to drought and salinity stresses in terms of root water uptake model parameters

    OpenAIRE

    Yanagawa, Aki; Fujimaki, Haruyuki

    2013-01-01

    Canola (Brassica napus) is cultivated for oil as a biofuel crop. Few quantitative data concerning its tolerance to abiotic stresses has been presented. We evaluated the tolerances of canola to drought and salinity stresses in terms of parameter values in a macroscopic root water uptake model. We conducted an experiment using nine columns with two plants in each: three columns were under drought stresses, another three were under saline stress and others provided potential transpiration. Two s...

  12. Non-linear effects of drought under shade: reconciling physiological and ecological models in plant communities

    OpenAIRE

    Holmgren, M.; Gomez-Aparicio, L.; Quero, J.L.; Valladares, F.

    2011-01-01

    The combined effects of shade and drought on plant performance and the implications for species interactions are highly debated in plant ecology. Empirical evidence for positive and negative effects of shade on the performance of plants under dry conditions supports two contrasting theoretical models about the role of shade under dry conditions: the trade-off and the facilitation hypotheses. We performed a meta-analysis of field and greenhouse studies evaluating the effects of drought at two ...

  13. Analysing drought impacts and recovery options by adapting a dairy farming systems modelling approach

    OpenAIRE

    Armstrong, Dan P.; Ho, Christie K.M.; Doyle, Peter T.; Malcolm, Bill; Gibb, I; Brown, Stuart

    2005-01-01

    The dairy industry in northern Victoria faced dramatic changes between 2001/02 and 2002/03. Drought resulted in a substantial decrease in availability, and subsequent increase in price, of irrigation water and supplementary feed. Most farms recorded substantial net cash flow deficits. Prior to 2002/03, a project had been established using case studies and a spreadsheet model to examine potential futures for different farm types. This approach was successfully adapted to examine drought impact...

  14. Agriculture Drought Risk Management Using Standardized Precipitation Index and AEZ Model

    Directory of Open Access Journals (Sweden)

    M. H. Nazarifar

    2014-01-01

    Full Text Available The objective of this study was to assess the drought risk management in the region under study. The SPI method was adopted for drought monitoring in Hamadan Province, Iran. The temporal and spatial extent of the area vulnerable to drought was delineated using AEZ model, GIS and other softwares. Five zones were recognized based on the drought severity index. Selection of compatible crops with respect to climate and land production capability of a region specially in drought condition is one of the effective elements to increase the water productivity in agriculture, based on Agro-ecological Zoning(AEZ model, developed by FAO, suitable spatial extension of wheat cultivation, which is the main crop in Hamadan Province, were delineated. According to this study the most suitable lands potentially available for wheat production are located in the north-east region and a part of the central region, where as, least suitable ones can be observed in the north-east and the south – east regions. The results of the risk analysis study show that south-east, north and central regions are susceptible to longest duration intense droughts where as long duration droughts are intensive in north, west and south-east regions. The overlaid and integrated maps of risks with the maps obtained after applying the AEZ model resulted into the map of spatial suitability of potential crop production for each class of risk (longest duration and most intensive durations. This enables the decision makers to define spatial priority of crop cultivation and manage various potential regions susceptible to drought risks.

  15. Are droughts occurrence and severity aggravating? A study on SPI drought class transitions using loglinear models and ANOVA-like inference

    Directory of Open Access Journals (Sweden)

    E. E. Moreira

    2011-12-01

    Full Text Available Long time series (95 to 135 yr of the Standardized Precipitation Index (SPI computed with the 12-month time scale relative to 10 locations across Portugal were studied with the aim of investigating if drought frequency and severity are changing through time. Considering four drought severity classes, time series of drought class transitions were computed and later divided into 4 or 5 sub-periods according to length of time series. Drought class transitions were calculated to form a 2-dimensional contingency table for each period. Two-dimensional loglinear models were fitted to these contingency tables and an ANOVA-like inference was then performed in order to investigate differences relative to drought class transitions among those sub-periods, which were considered as treatments of only one factor. The application of ANOVA-like inference to these data allowed to compare the four or five sub-periods in terms of probabilities of transition between drought classes, which were used to detect a possible trend in time evolution of droughts frequency and severity that could be related to climate change. Results for a number of locations show some similarity between the first, third and fifth period (or the second and the fourth if there were only 4 sub-periods regarding the persistency of severe/extreme and sometimes moderate droughts. In global terms, results do not support the assumption of a trend for progressive aggravation of droughts occurrence during the last century, but rather suggest the existence of long duration cycles.

  16. Modeling of severe persistent droughts over eastern China during the last millennium

    Science.gov (United States)

    Peng, Y.; Shen, C.; Cheng, H.; Xu, Y.

    2014-05-01

    We use proxy data and modeled data from 1000 year model simulations with a variety of climate forcings to examine the occurrence of severe event of persistent drought over eastern China during the last millennium and diagnose the mechanisms. Results show that the model was able to roughly simulate most of these droughts over the study area during the last millennium such as those that occurred during the periods of 1123-1152, 1197-1223, 1353-1363, 1428-1449, 1479-1513, and 1632-1645. Our analyses suggest that these six well-captured droughts may caused by the East Asian summer monsoon (EASM) weakening. Study on the wavelet transform and spectral analysis reveals these events occurred all at the statistically significant 15-35-year timescale. A modeled data intercomparison suggests the possibility that solar activity may be the primary driver in the occurrence of the 1129-1144, 1354-1365, 1466-1491 and 1631-1648 droughts as identified by the model. However another possibility that these events may be related to internal variability cannot be excluded. Although the El Niño-Southern Oscillation (ENSO) plays an important role in monsoon variability, a temporally consistent relationship between the droughts and SST pattern in the Pacific Ocean could not be found either in the modeled or proxy data. Our analyses also indicate that large volcanic eruptions play a role as an amplifier in the drought of 1631-1648 and caused the droughts of 1830-1853 and 1958-1976, which was identified by the model.

  17. Modeling monthly mean air temperature for Brazil

    Science.gov (United States)

    Alvares, Clayton Alcarde; Stape, José Luiz; Sentelhas, Paulo Cesar; de Moraes Gonçalves, José Leonardo

    2013-08-01

    Air temperature is one of the main weather variables influencing agriculture around the world. Its availability, however, is a concern, mainly in Brazil where the weather stations are more concentrated on the coastal regions of the country. Therefore, the present study had as an objective to develop models for estimating monthly and annual mean air temperature for the Brazilian territory using multiple regression and geographic information system techniques. Temperature data from 2,400 stations distributed across the Brazilian territory were used, 1,800 to develop the equations and 600 for validating them, as well as their geographical coordinates and altitude as independent variables for the models. A total of 39 models were developed, relating the dependent variables maximum, mean, and minimum air temperatures (monthly and annual) to the independent variables latitude, longitude, altitude, and their combinations. All regression models were statistically significant ( α ≤ 0.01). The monthly and annual temperature models presented determination coefficients between 0.54 and 0.96. We obtained an overall spatial correlation higher than 0.9 between the models proposed and the 16 major models already published for some Brazilian regions, considering a total of 3.67 × 108 pixels evaluated. Our national temperature models are recommended to predict air temperature in all Brazilian territories.

  18. Predicting Agricultural Drought using NOAH Land Surface Model, MODIS Evapotranspiration and GRACE Terrestrial Water Storage

    Science.gov (United States)

    wu, J.; Zhang, X.

    2013-12-01

    Drought is a major natural hazard in the world which costs 6-8 billion per year in the United States. Drought monitoring and prediction are difficult because it usually develops slowly and it is hard to be recognized until it becomes severe. The severity of agricultural drought was estimated by using Soil Moisture Deficit Index (SMDI) based on soil moisture simulated by Noah land surface model. Based on general water balance and delayed response of soil moisture to the forcing of climate variables, a Multiple Linear Regression (MLR) model for agricultural drought prediction was developed, the inputs of which included data at the previous one and two months of precipitation from Parameter-elevation Regressions on Independent Slopes Model (PRISM), evapotranspiration from MODIS MOD 16 product and terrestrial water storage (TWS) derived from Gravity Recovery and Climate Experiment (GRACE). The stability of the MLR model is tested using different training datasets from 2003 to 2009 with time spans of one year to six years and the results indicated that the model is stable, with very limited changes in estimated parameters between different datasets. A sensitivity analysis shows that evapotranspiration is the most significant variable affecting soil moisture change compared to precipitation and TWS. The predicted SMDI was compared with U.S. drought monitor products to evaluate its performance for the period of 2010-2012 when a severe drought occurred in the U.S. (Fig.1). The predicted SMDI successfully forecasted the severe drought in the southern U.S. in early 2012 and its expansion in the following summer. The MLR model has a high predictive skill with short-term forecast (1-2 months), while less accuracy is observed for the long-term forecast (3-6 months) (Fig.2).

  19. Do land surface models need to include differential plant species responses to drought? Examining model predictions across a mesic-xeric gradient in Europe

    Science.gov (United States)

    De Kauwe, M. G.; Zhou, S.-X.; Medlyn, B. E.; Pitman, A. J.; Wang, Y.-P.; Duursma, R. A.; Prentice, I. C.

    2015-12-01

    Future climate change has the potential to increase drought in many regions of the globe, making it essential that land surface models (LSMs) used in coupled climate models realistically capture the drought responses of vegetation. Recent data syntheses show that drought sensitivity varies considerably among plants from different climate zones, but state-of-the-art LSMs currently assume the same drought sensitivity for all vegetation. We tested whether variable drought sensitivities are needed to explain the observed large-scale patterns of drought impact on the carbon, water and energy fluxes. We implemented data-driven drought sensitivities in the Community Atmosphere Biosphere Land Exchange (CABLE) LSM and evaluated alternative sensitivities across a latitudinal gradient in Europe during the 2003 heatwave. The model predicted an overly abrupt onset of drought unless average soil water potential was calculated with dynamic weighting across soil layers. We found that high drought sensitivity at the most mesic sites, and low drought sensitivity at the most xeric sites, was necessary to accurately model responses during drought. Our results indicate that LSMs will over-estimate drought impacts in drier climates unless different sensitivity of vegetation to drought is taken into account.

  20. Do land surface models need to include differential plant species responses to drought? Examining model predictions across a latitudinal gradient in Europe

    OpenAIRE

    M. G. De Kauwe; S.-X. Zhou; B. E. Medlyn; Pitman, A.J.; Y.-P. Wang; R. A. Duursma; Prentice, I. C.

    2015-01-01

    Future climate change has the potential to increase drought in many regions of the globe, making it essential that land surface models (LSMs) used in coupled climate models, realistically capture the drought responses of vegetation. Recent data syntheses show that drought sensitivity varies considerably among plants from different climate zones, but state-of-the-art LSMs currently assume the same drought sensitivity for all vegetation. We tested whether variable ...

  1. Reconstructing and analyzing China's fifty-nine year (1951–2009 drought history using hydrological model simulation

    Directory of Open Access Journals (Sweden)

    Z. Y. Wu

    2011-02-01

    Full Text Available The recent fifty-nine year (1951–2009 drought history of China is reconstructed using daily soil moisture values generated by the Variable Infiltration Capacity (VIC land surface macroscale hydrology model. VIC is applied over a grid of 10 458 points with a spatial resolution of 30 km × 30 km, and is driven by observed daily maximum and minimum air temperature and precipitation from 624 long-term meteorological stations. The VIC soil moisture is used to calculate the Soil Moisture Anomaly Percentage Index (SMAPI, which can be used as a measure of the severity of agricultural drought on a global basis. We develop a SMAPI-based drought identification procedure for practical uses in the identification of both grid point and regional drought events. As the result, a total of 325 regional drought events varying in time and strength are identified from China's nine drought study regions. These drought events can thus be assessed quantitatively at different spatial and temporal scales. The result shows that the severe drought events of 1978, 2000 and 2006 are well reconstructed, indicating SMAPI is capable of indentifying the onset of a drought event, its progressing, as well as its ending. Spatial and temporal variations of droughts on China's nine drought study regions are studied. Our result shows that on average, up to 30% of the total area of China is prone to drought. Regionally, an upward trend in drought-affected areas has been detected in three regions Inner Mongolia, Northeast and North during the recent fifty-nine years. However, the decadal variability of droughts has been week in the rest five regions South, Southwest, East, Northwest, and Tibet. Xinjiang has even been wetting steadily since the 1950s. Two regional dry centers are discovered in China as the result of a combined analysis on the occurrence of drought events from both grid points and drought study regions. The first center is located in the area partially covered by two

  2. Making the distinction between water scarcity and drought using an observation-modeling framework

    Science.gov (United States)

    Loon, A. F.; Lanen, H. A. J.

    2013-03-01

    Drought and water scarcity are keywords for river basin management in water-stressed regions. "Drought" is a natural hazard, caused by large-scale climatic variability, and cannot be prevented by local water management. "Water scarcity" refers to the long-term unsustainable use of water resources, which water managers can influence. Making the distinction between drought and water scarcity is not trivial, because they often occur simultaneously. In this paper, we propose an observation-modeling framework to separate natural (drought) and human (water scarcity) effects on the hydrological system. The basis of the framework is simulation of the situation that would have occurred without human influence, the "naturalized" situation, using a hydrological model. The resulting time series of naturalized state variables and fluxes are then compared to observed time series. As second, more important and novel step, anomalies (i.e., deviations from a threshold) are determined from both time series and compared. We demonstrate the use of the proposed observation-modeling framework in the Upper-Guadiana catchment in Spain. Application of the framework to the period 1980-2000 shows that the impact of groundwater abstraction on the hydrological system was, on average, four times as high as the impact of drought. Water scarcity resulted in disappearance of the winter high-flow period, even in relatively wet years, and a nonlinear response of groundwater. The proposed observation-modeling framework helps water managers in water-stressed regions to quantify the relative impact of drought and water scarcity on a transient basis and, consequently, to make decisions regarding adaptation to drought and combating water scarcity.

  3. Effects of Planting Density on Transpiration, Stem Flow and Interception for Two Clones Differing in Drought Tolerance in a High Productivity Eucalyptus Plantation in Brazil

    Science.gov (United States)

    Hubbard, R. M.; Hakemada, R.; Ferraz, S.

    2015-12-01

    Eucalypt plantations cover about 20 M hectares worldwide and expansion is expected to mainly occur in marginal growing areas where dry conditions may lead to water conflicts. One of the principal reasons for the expansion of Eucalyptus plantations is rapid wood growth but these forests also transpire large amounts of water. Genotype selection and planting density, are key factors regulating carbon and water tradeoffs at a stand scale, but few studies have examined these simultaneously especially in highly productive clonal plantations. Our goal in this study was to examine the effects of planting density on carbon and water interactions using a drought tolerant and drought sensitive eucalyptus clone. This work is part of a larger study (TECHS project - Tolerance of Eucalyptus Clones to Hydric and Thermal Stresses) and is located in a flat Oxisol in southeast of Brazil. A drought tolerant (E. grandis x E. camaldulensis (Grancam) and drought sensitive clone E. grandis x E. urophylla (Urograndis) were planted at four densities ranging from 600 to 3.000 stem ha-1. We measured transpiration using thermal heat dissipation probes, wood growth, canopy interception and stemflow during a full year (21 to 33 months old). Precipitation during the study period was 738 mm. Independently of genetics, growth increased with increasing density. Transpiration also increased with planting density and ranged from 515-595 mm at wider spacing to 735-978 mm at tighter spacing. Interception increased with planting density representing 18-22% of precipitation versus 13-14% in wider spacing while stem flow represented 2-5% in denser spacing and 1-2% at broader spacing. When density was higher than 1.250 and 1.750 stems ha-1 in Urograndis and Grancam clones, respectively, the water balance were negative. On a stand scale, results show both genetics and spacing can be used as silvicultural tools to better manage the tradeoff between wood growth and water consumption.

  4. Assessing human impact on droughts in a tropical Vietnamese catchment using a combined modelling approach

    Science.gov (United States)

    Nauditt, Alexandra; Birkel, Christian; Ribbe, Lars; Tran Van, Tra; Viet, Trinh Quoc; Firoz, Abm; Fink, Manfred

    2015-04-01

    Historical drought frequency, drought risk and types are still poorly investigated in tropical regions and particularly in South East Asia. However, evolving drought periods during the dry season severely impact on socio economic factors such as livelihood (irrigated rice production), hydropower generation and urban water supply in such regions as in the VuGiaThuBon river basin (10,350 km²) in Central Vietnam. Besides the increasing frequency of heat waves and prolonged dry periods without rainfall, hydropower development and over-exploitation of water resources due to demographic and socioeconomic development are the main causes for drought-related disasters and subsequent salt water intrusion. Precipitation and runoff time series from 1982 to 2009 were used to assess drought severity and typology before hydropower development started in 2010. We applied different rainfall-runoff modelling approaches of increasing complexity (HBV light, J2000 and Mike NAM) as well as meteorological and hydrological drought indices such as the Standardized Precipitation Index (SPI) and its runoff homologue (SRI). In the scope of the BMBF funded research project "Land use and Climate Change interactions (LUCCi)" (www.lucci-vietnam.info), the impacts of the human-induced hydrological alterations on drought risk were quantified by integrating the distributed physically-based hydrological model J2000 with the reservoir operation tool HEC ResSim and the River basin model Mike Basin to simulate the runoff to the coastal system. The salt water intrusion behavior in the flat coastal area was represented by the hydrodynamic Mike 11 model relating low flow thresholds to salt intrusion. The different discharge simulations before and after the reservoir construction were compared and evaluated regarding their relevance for the drought severity being dominated either by meteorological dry spells or hydrological alterations. Results show a clear impact of the hydropower reservoir and resulting

  5. A Physical Model for Extreme Drought over Southwest Asia

    Science.gov (United States)

    Hoell, A.; Barlow, M. A.; Funk, C. C.; Cannon, F.

    2015-12-01

    The socioeconomic difficulties of Southwest Asia, defined as the area bound by the domain 25°N-40°N and 40°E-70°E, which includes the countries of Iran, Afghanistan and Pakistan, are exacerbated by extreme precipitation deficits during the November-April rainy season. The precipitation deficits during many Southwest Asia droughts have been examined in terms of the forcing by climate variability originating over the Pacific Ocean as a result of the El Niño-Southern Oscillation (ENSO), Pacific Decadal Variability (PDV) and the long-term warming of Pacific (LT) sea surface temperatures (SST). Here, we 1) examine how the most extreme November-April Southwest Asia droughts relate to global SSTs and the associated large-scale atmospheric circulation anomalies, 2) analyze the specific atmospheric forcing mechanisms responsible for changes in regional Southwest Asian precipitation and 3) examine the causal mechanisms responsible for the increased frequency of Southwest Asia drought in recent decades. The driest November-April seasons during 1948-2012 over Southwest Asia are forced by subsidence and reductions of moisture fluxes as a result of the interaction of the mean flow with anomalous zonally-symmetric high pressure throughout the Northern Hemisphere. The anomalous zonally-symmetric high pressure throughout the Northern Hemisphere occurs simultaneously with cool central and eastern Pacific SST anomalies associated with La Niña and the negative phase of PDV and a warm west Pacific Ocean caused in part by the long-term warming of the west Pacific Ocean. The long-term warming of the Pacific Ocean has driven the regional precipitation declines in recent decades, with the strongest signal occurring over areas bordering the Arabian Sea.

  6. Reconstructing and analyzing China's fifty-nine year (1951–2009 drought history using hydrological model simulation

    Directory of Open Access Journals (Sweden)

    Z. Y. Wu

    2011-09-01

    Full Text Available The 1951–2009 drought history of China is reconstructed using daily soil moisture values generated by the Variable Infiltration Capacity (VIC land surface macroscale hydrology model. VIC is applied over a grid of 10 458 points with a spatial resolution of 30 km × 30 km, and is driven by observed daily maximum and minimum air temperature and precipitation from 624 long-term meteorological stations. The VIC soil moisture is used to calculate the Soil Moisture Anomaly Percentage Index (SMAPI, which can be used as a measure of the severity of agricultural drought on a global basis. We have developed a SMAPI-based drought identification procedure for practical uses in the identification of both grid point and regional drought events. As a result, a total of 325 regional drought events varying in time and strength are identified from China's nine drought study regions. These drought events can thus be assessed quantitatively at different spatial and temporal scales. The result shows that the severe drought events of 1978, 2000 and 2006 are well reconstructed, which indicates that the SMAPI is capable of identifying the onset of a drought event, its progression, as well as its termination. Spatial and temporal variations of droughts in China's nine drought study regions are studied. Our result shows that on average, up to 30% of the total area of China is prone to drought. Regionally, an upward trend in drought-affected areas has been detected in three regions (Inner Mongolia, Northeast and North from 1951–2009. However, the decadal variability of droughts has been weak in the rest of the five regions (South, Southwest, East, Northwest, and Tibet. Xinjiang has even been showing steadily wetter since the 1950s. Two regional dry centres are discovered in China as the result of a combined analysis on the occurrence of drought events from both grid points and drought study regions. The first centre is located in the area partially covered by the North

  7. Evaluating the Potential Use of Remotely-Sensed and Model-Simulated Soil Moisture for Agricultural Drought Risk Monitoring

    Science.gov (United States)

    Yan, Hongxiang; Moradkhani, Hamid

    2016-04-01

    Current two datasets provide spatial and temporal resolution of soil moisture at large-scale: the remotely-sensed soil moisture retrievals and the model-simulated soil moisture products. Drought monitoring using remotely-sensed soil moisture is emerging, and the soil moisture simulated using land surface models (LSMs) have been used operationally to monitor agriculture drought in United States. Although these two datasets yield important drought information, their drought monitoring skill still needs further quantification. This study provides a comprehensive assessment of the potential of remotely-sensed and model-simulated soil moisture data in monitoring agricultural drought over the Columbia River Basin (CRB), Pacific Northwest. Two satellite soil moisture datasets were evaluated, the LPRM-AMSR-E (unscaled, 2002-2011) and ESA-CCI (scaled, 1979-2013). The USGS Precipitation Runoff Modeling System (PRMS) is used to simulate the soil moisture from 1979-2011. The drought monitoring skill is quantified with two indices: drought area coverage (the ability of drought detection) and drought severity (according to USDM categories). The effects of satellite sensors (active, passive), multi-satellite combined, length of climatology, climate change effect, and statistical methods are also examined in this study.

  8. Large-scale hydrological modelling in the semi-arid north-east of Brazil

    Energy Technology Data Exchange (ETDEWEB)

    Guentner, A.

    2002-09-01

    Semi-arid areas are characterized by small water resources. An increasing water demand due to population growth and economic development as well as a possible decreasing water availability in the course of climate change may aggravate water scarcity in future in these areas. The quantitative assessment of the water resources is a prerequisite for the development of sustainable measures of water management. For this task, hydrological models within a dynamic integrated framework are indispensable tools. The main objective of this study is to develop a hydrological model for the quantification of water availability over a large geographic domain of semi-arid environments. The study area is the Federal State of Ceara in the semi-arid north-east of Brazil. Surface water from reservoirs provides the largest part of water supply. The area has recurrently been affected by droughts which caused serious economic losses and social impacts like migration from the rural regions. (orig.)

  9. River water quality modelling under drought situations - the Turia River case

    Science.gov (United States)

    Paredes-Arquiola, Javier; Macián, Javier; Pedro-Monzonís, María; Belda, Edgar; Momblanch, Andrea; Andreu, Joaquín

    2016-10-01

    Drought and water shortage effects are normally exacerbated due to collateral impacts on water quality, since low streamflow affects water quality in rivers and water uses depend on it. One of the most common problems during drought conditions is maintaining a good water quality while securing the water supply to demands. This research analyses the case of the Turia River Water Resource System located in Eastern Spain. Its main water demand comes as urban demand from Valencia City, which intake is located in the final stretch of the river, where streamflow may become very low during droughts. As a result, during drought conditions concentrations of pathogens and other contaminants increase, compromising the water supply to Valencia City. In order to define possible solutions for the above-mentioned problem, we have developed an integrated model for simulating water management and water quality in the Turia River Basin to propose solutions for water quality problems under water scarcity. For this purpose, the Decision Support System Shell AQUATOOL has been used. The results demonstrate the importance of applying environmental flows as a measure of reducing pollutant's concentration depending on the evolution of a drought event and the state of the water resources system.

  10. Drought monitoring based on TIGGE and distributed hydrological model in Huaihe River Basin, China.

    Science.gov (United States)

    Zhao, Junfang; Xu, Jingwen; Xie, Xingmei; Lu, Houquan

    2016-05-15

    Drought assessment is important for developing measures to reduce agricultural vulnerability and thereby secure the livelihoods of those who depend on agriculture. This study uses four global ensemble weather prediction systems: the China Meteorological Administration (CMA), the European Centre for Medium-Range Weather Forecasts (ECMWF), the UK Met Office (UKMO), and the US National Centres for Environmental Prediction (NCEP) in the THORPEX (The Observing System Research and Predictability Experiment) Interactive Grand Global Ensemble (TIGGE) archive from 2006 to 2010. Based on results from the XXT (the first X denotes Xinanjiang, the second X denotes hybrid, and the T denotes TOPMODEL) distributed hydrological model, as well as soil moisture observations and digital elevation model (DEM) data, synthesized drought grades were established in the Huaihe River Basin of China. To filter out the impact of short-term fluctuations on observed soil moisture, a 30-day moving average was calculated. Use of the moving average significantly improves the correlation between observed soil moisture and simulated soil water deficit depth. Finally, a linear regression model describing the relationship between observed soil moisture and simulated soil water deficit depth was constructed. The deterministic regression coefficient was 0.5872, the correlation coefficient was 0.77, and the regression coefficient was -154.23. The trends in drought grades calculated using soil moisture and soil water deficit depth were found to be the same, and the grades agreed to within one level. Our findings highlight the importance of synthesizing drought grading when assessing drought using different soil moisture indicators in order to obtain a more comprehensive forecast of drought conditions. PMID:26930309

  11. Application of Multiple Evaluation Models in Brazil

    Directory of Open Access Journals (Sweden)

    Rafael Victal Saliba

    2008-07-01

    Full Text Available Based on two different samples, this article tests the performance of a number of Value Drivers commonly used for evaluating companies by finance practitioners, through simple regression models of cross-section type which estimate the parameters associated to each Value Driver, denominated Market Multiples. We are able to diagnose the behavior of several multiples in the period 1994-2004, with an outlook also on the particularities of the economic activities performed by the sample companies (and their impacts on the performance through a subsequent analysis with segregation of companies in the sample by sectors. Extrapolating simple multiples evaluation standards from analysts of the main financial institutions in Brazil, we find that adjusting the ratio formulation to allow for an intercept does not provide satisfactory results in terms of pricing errors reduction. Results found, in spite of evidencing certain relative and absolute superiority among the multiples, may not be generically representative, given samples limitation.

  12. Comparison of drought stress indices in beech forests: a modelling study

    Directory of Open Access Journals (Sweden)

    Vilhar U

    2016-08-01

    Full Text Available Two drought stress indices were applied to managed as well as old-growth beech forests and gaps for the 2001 to 2013 period to aid in the development of an efficient tool for field water supply diagnosis. The relative extractable soil water (REW, which was calculated from the soil water content in the root zone, and the transpiration index (TI, calculated as the ratio between the actual and potential transpiration were used. Both indices were calculated on a daily basis using the water balance model BROOK90, which was fitted and tested using measured data on throughfall and soil water content. A sensitivity analysis apportioned to the input parameters of the drought stress indices was conducted to assess uncertainty. Both drought stress indices showed the greatest drought stress in the years 2009, 2003 and 2011, as also indicated by the Standardized Precipitation Evapotranspiration Index (SPEI at the nearest meteorological station. However, drought stress intensity and duration differed between the indices and study sites. Greater water supply stress was shown in the forests than the gaps. Furthermore, the agreement among the indices was smaller for gaps compared with forests, which implies that careful index selection is needed when comparing water supply stresses in different stages of forest stand development. Due to the low amount of input data required and the parameters that can be measured with relative ease in the field, REW might be an efficient tool for field water supply diagnosis when analyzing the drought stresses of similar forest types and at unique stages of development. REW satisfactorily indicated drought stress in forests but to a lesser extent in gaps. TI demonstrated more consistent differences in drought stress between forests and gaps and therefore proved to be the appropriate index for a detailed analysis of drought stress variation between different stages of forest stand development. However, due to a greater number of

  13. Drought, Fire and Insects in Western US Forests: Observations to Improve Regional Land System Modeling

    Science.gov (United States)

    Law, B. E.; Yang, Z.; Berner, L. T.; Hicke, J. A.; Buotte, P.; Hudiburg, T. W.

    2015-12-01

    Drought, fire and insects are major disturbances in the western US, and conditions are expected to get warmer and drier in the future. We combine multi-scale observations and modeling with CLM4.5 to examine the effects of these disturbances on forests in the western US. We modified the Community Land Model, CLM4.5, to improve simulated drought-related mortality in forests, and prediction of insect outbreaks under future climate conditions. We examined differences in plant traits that represent species variation in sensitivity to drought, and redefined plant groupings in PFTs. Plant traits, including sapwood area: leaf area ratio and stemwood density were strongly correlated with water availability during the ecohydrologic year. Our database of co-located observations of traits for 30 tree species was used to produce parameterization of the model by species groupings according to similar traits. Burn area predicted by the new fire model in CLM4.5 compares well with recent years of GFED data, but has a positive bias compared with Landsat-based MTBS. Biomass mortality over recent decades increased, and was captured well by the model in general, but missed mortality trends of some species. Comparisons with AmeriFlux data showed that the model with dynamic tree mortality only (no species trait improvements) overestimated GPP in dry years compared with flux data at semi-arid sites, and underestimated GPP at more mesic sites that experience dry summers. Simulations with both dynamic tree mortality and species trait parameters improved estimates of GPP by 17-22%; differences between predicted and observed NEE were larger. Future projections show higher productivity from increased atmospheric CO2 and warming that somewhat offsets drought and fire effects over the next few decades. Challenges include representation of hydraulic failure in models, and availability of species trait and carbon/water process data in disturbance- and drought-impacted regions.

  14. Market Anatomy of a Drought: Modeling Barge and Corn Market Adaptation to Reduced Rainfall and Low Mississippi River Water Levels During the 2012 Midwestern U.S. Drought

    Science.gov (United States)

    Foster, B.; Characklis, G. W.; Thurman, W. N.

    2015-12-01

    In mid 2012, a severe drought swept across the Midwest, the heartland of corn production in the U.S. When the drought persisted into late Fall, corn markets were affected in two distinct ways: (1) reduced rainfall led to projected and actual corn yields that were lower than expected and (2) navigation restrictions, a result of low water levels on the Mississippi River, disrupted barge transportation, the most common and inexpensive mode for moving corn to many markets. Both (1) and (2) led to significant financial losses, but due to the complexity of the economic system and the coincidence of two different market impacts, the size of the role that low water levels played wass unclear. This is important, as losses related to low water levels are used to justify substantial investments in dredging activities on the Mississippi River. An "engineering" model of the system, suggests that low water levels should drive large increases in barge and corn prices, while some econometric models suggest that water levels explain very little of the changes in barge rates and corn prices. Employing a model that integrates both the engineering and economic elements of the system indicates that corn prices and barge rates during the drought display spatial and temporal behavior that is difficult to explain using either the engineering or econometric models alone. This integrated model accounts for geographic and temporal variations in drought impacts and identifies unique market responses to four different sets of conditions over the drought's length. Results illustrate that corn and barge price responses during the drought were a product of comingled, but distinct, reactions to both supply changes and navigation disruptions. Results also provide a more structured description of how the economic system that governs corn allocation interacts with the Mississippi River system during drought. As both public and private parties discuss potential managerial or infrastructural methods

  15. Multi-environment QTL mixed models for drought stress adaptation in wheat

    NARCIS (Netherlands)

    Mathews, K.L.; Malosetti, M.; Chapman, S.; McIntyre, L.; Reynolds, M.; Shorter, R.; Eeuwijk, van F.A.

    2008-01-01

    Many quantitative trait loci (QTL) detection methods ignore QTL-by-environment interaction (QEI) and are limited in accommodation of error and environment-specific variance. This paper outlines a mixed model approach using a recombinant inbred spring wheat population grown in six drought stress tria

  16. Non-linear effects of drought under shade: reconciling physiological and ecological models in plant communities

    NARCIS (Netherlands)

    Holmgren, M.; Gomez-Aparicio, L.; Quero, J.L.; Valladares, F.

    2012-01-01

    The combined effects of shade and drought on plant performance and the implications for species interactions are highly debated in plant ecology. Empirical evidence for positive and negative effects of shade on the performance of plants under dry conditions supports two contrasting theoretical model

  17. Joint meteorological and hydrological drought model: a management tool for proactive water resources planning of semi-arid regions

    Science.gov (United States)

    Modaresi Rad, Arash; Ahmadi Ardakani, Samira; Ghahremani, Zahra; Ghahreman, Bijan; Khalili, Davar

    2016-04-01

    Conventionally drought analysis has been limited to single drought category. Utilization of models incorporating multiple drought categories, can relax this limitation. A copula-based model is proposed, which uses meteorological and hydrological drought indices to assess drought events for ultimate management of water resources, at small scales, i.e., sub-watersheds. The study area is a sub basin located at Karkheh watershed (western Iran), utilizing 41-year data of 4 raingauge stations and one hydrometric station located upstream and at the outlet respectively. Prior to drought analysis, time series of precipitation and streamflow records are investigated for possible dependency/significant trend. Considering the semi-arid nature of the study area, boxplots are utilized to graphically capture the rainy months, which used to evaluate the degree of correlation between streamflow and precipitation records via nonparametric correlations and bivariate tail dependence. Time scales of 3- and 12-month are considered, which are used to study vulnerability of early vegetation establishment and long-term ecosystem resilience, respectively. Among four common goodness of fit tests, the Cramér-von-Mises is found preferable for defining copula distribution functions through Akaike & Bayesian information criteria and coefficient of determination. Furthermore the uncertainty associated with different copula models is measured using the concept of entropy. A new bivariate drought modeling approach is proposed through copulas. The proposed index, named standardized precipitation-streamflow index (SPSI) is compared with two separate indices of streamflow drought index (SDI) and standardized precipitation index (SPI). According to results, the SPSI could detect onset of droughts dominated by precipitation as is similarly indicated by SPI index. It also captures discordant case of normal period precipitation with dry period streamflow and vice versa. Finally, combination of severity

  18. 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.

  19. Identification of drought and frequency analysis of drought characteristics based on palmer drought severity index model%基于帕尔默旱度模式的干旱识别及其特征值频率分析

    Institute of Scientific and Technical Information of China (English)

    周玉良; 刘立; 周平; 金菊良; 郦建强; 吴成国

    2014-01-01

    from 1951 to 2011 were conducted. There were 43 droughts were identified, and the drought that occurred in 2009-2010 was the most severe drought event in the study period with the recurrence period of 64.7 years. Results showed that drought process indentified based on the PSDI model was consistent with the actual regional drought circumstances and the results by using runoff index methods, notwithstanding the disparity from that by applying the precipitation index that were not concerned with surface hydrological process. The proposed drought frequency analysis was of clear physical concept, and the expression of drought duration and severity was of physically reasonability. The results of this study can provide a reference for assessment of drought disaster hazard.

  20. Process-based simulation of seasonality and drought stress in monoterpene emission models

    Directory of Open Access Journals (Sweden)

    R. Grote

    2009-09-01

    Full Text Available Canopy emissions of volatile hydrocarbons such as isoprene and monoterpenes play an important role in air chemistry. They depend on various environmental conditions, are highly species-specific and are expected to be affected by global change. In order to estimate future emissions of these isoprenoids, differently complex models are available. However, seasonal dynamics driven by phenology, enzymatic activity, or drought stress strongly modify annual ecosystem emissions. Although these impacts depend themselves on environmental conditions, they have yet received little attention in mechanistic modelling.

    In this paper we propose the application of a mechanistic method for considering the seasonal dynamics of emission potential using the ''Seasonal Isoprenoid synthase Model'' (Lehning et al., 2001. We test this approach with three different models (GUENTHER, Guenther et al., 1993; NIINEMETS, Niinemets et al., 2002a; BIM2, Grote et al., 2006 that are developed for simulating light-dependent monoterpene emission. We also suggest specific drought stress representations for each model. Additionally, the proposed model developments are compared with the approach realized in the MEGAN (Guenther et al., 2006 emission model. Models are applied to a Mediterranean Holm oak (Quercus ilex site with measured weather data.

    The simulation results demonstrate that the consideration of a dynamic emission potential has a strong effect on annual monoterpene emission estimates. The investigated models, however, show different sensitivities to the procedure for determining this seasonality impact. Considering a drought impact reduced the differences between the applied models and decreased emissions at the investigation site by approximately 33% on average over a 10 year period. Although this overall reduction was similar in all models, the sensitivity to weather conditions in specific years was different. We conclude that the proposed

  1. Modelling soil water content variations under drought stress on soil column cropped with winter wheat

    OpenAIRE

    Csorba, Szilveszter; Raveloson, Andrea; Tóth, Estzer; Nagy, Viliam; Farkas, Csilla

    2014-01-01

    Mathematical models are effective tools for evaluating the impact of predicted climate change on agricultural production, but it is difficult to test their applicability to future weather conditions. We applied the SWAP model to assess its applicability to climate conditions, differing from those, for which the model was developed. We used a database obtained from a winter wheat drought stress experiment. Winter wheat was grown in six soil columns, three having optimal water supply (NS), whil...

  2. Revisiting mechanisms underlying tree mortality induced by drought in the Amazon: from observation to modeling

    Science.gov (United States)

    Joetzjer, E.; Poulter, B.; Ciais, P.; Sala, A.; Sack, L.; Bartlett, M.

    2015-12-01

    In the past decade, two extreme droughts experienced by the Amazon rainforest led to a perturbation of carbon cycle dynamics and forest structure, partly through an increase in tree mortality. While there is a relatively strong consensus in CMIP5 projections for an increase in both frequency and intensity of droughts across the Amazon, the potential for forest die-off constitutes a large uncertainty in projections of climate impacts on terrestrial ecosystems and carbon cycle feedbacks. Two long-term through fall exclusion experiments (TFE) provided novel observations of Amazonian ecosystem responses under drought. These experiments also provided a great opportunity to evaluate and improve models' behavior under drought by comparing simulations and observations. While current DGVM use a wide array of algorithms to represent mortality, most are associated with large uncertainty for representing drought-induced mortality, and require updating to include current information of physiological processes. During very strong droughts, the leaves desiccate and stems may undergo catastrophic embolism. However, even before that point, stomata close, to minimize excessive water loss and risk of hydraulic failure, which reduces carbon assimilation. To maintain respiration and other functions, plants may eventually deplete stored non-structural carbon compounds (NSC), which may have negative impacts on plant and eventually increase the probability of mortality.Here, we describe a new parameterization of the mortality process induced by drought using the ORCHIDEE-CAN dynamic vegetation model and test it using the two TFE results. We first updated and evaluated both the representation of hydraulic architecture and the NSC pool dynamics using in situ data. We implemented a direct climate effect on mortality through catastrophic stem embolism, based on hydraulic vulnerability curves. In addition, we explored the role of NSC on hydraulic failure and mortality by coupling in the model

  3. Thresholds in vegetation responses to drought: Implications for rainfall-runoff modeling

    Science.gov (United States)

    Tague, C.; Dugger, A. L.

    2011-12-01

    While threshold behavior is often associated with soil and subsurface runoff generation, dynamic vegetation responses to water stress may be an important contributor to threshold type behavior in rainfall runoff models. Vegetation water loss varies with vegetation type and biomass and transpiration dynamics in many settings are regulated by stomatal function. In water limited environments the timing and frequency of stomatal closure varies from year to year as a function of water stress. Stomatal closure and associated fine time scale (hourly to weekly) plant transpiration may appear as threshold (on/off) behavior. Total seasonal to annual plant water use, however, typically show a continuous relationship with atmospheric conditions and soil moisture. Thus while short-time scale behavior may demonstrate non-linear, threshold type behavior, continuous relationships at slightly longer time scales can be used to capture the role of vegetation mediated water loss and its associated impact on storage and runoff. Many rainfall runoff models rely on these types of relationships. However these relationships may change if water stress influences vegetation structure as it does in drought conditions. Forest dieback under drought is a dramatic example of a threshold event, and one that is expected to occur with increasing frequency under a warmer climate. Less dramatic but still important are changes in leaf and root biomass in response to drought. We demonstrate these effects using a coupled ecosystem carbon cycling and hydrology model and show that by accounting for drought driven changes in vegetation dynamics we improve our ability to capture inter-annual variation in streamflow for a semi-arid watershed in New Mexico. We also use the model to predict spatial patterns of more catastrophic vegetation dieback with moisture stress and show that we can accurately capture the spatial pattern of ponderosa pine dieback during a early 2000s drought in New Mexico. We use these

  4. Future changes in drought characteristics over Southern South America projected by a CMIP5 multi-model ensemble

    Science.gov (United States)

    Rivera, J. A.; Penalba, O. C.

    2013-05-01

    The impact of climate change on drought main characteristics (frequency, duration and severity) was assessed over Southern South America through the precipitation outputs from a multi-model ensemble of 15 climate models of the Coupled Model Intercomparison Project Phase 5 (CMIP5). The Standardized Precipitation Index was used as a drought indicator, given its temporal flexibility and simplicity. Changes in drought characteristics were identified by the difference for early (2011-2040) and late (2071-2100) 21st century values with respect to the 1979-2008 baseline. In order to evaluate the multi-model outputs, model biases where identified through a comparison with the drought characteristics from the Global Precipitation Climatology Centre database for the baseline period. Future climate projections under moderate- and high-emission scenarios showed that the occurrence of short-term and long-term droughts will be more frequent in the 21st century, with shorter durations and greater severities over much of the study area. This result is independent on the scenario considered, since no significant differences were observed on drought changes. Taking into account that in most of the region the multi-model ensemble tends to produce less number of droughts, with higher duration and lower severity, the future changes scenario might be even more dramatic. Therefore, Southern South America could experience more frequent water shortages with significant economic losses if proper adaptation measures are not proposed timely.

  5. On the spatio-temporal analysis of hydrological droughts from global hydrological models

    OpenAIRE

    Corzo Perez, G.A.; M. H. J. van Huijgevoort; F. Voß; H. A. J. van Lanen

    2011-01-01

    The recent concerns for world-wide extreme events related to climate change have motivated the development of large scale models that simulate the global water cycle. In this context, analysis of hydrological extremes is important and requires the adaptation of identification methods used for river basin models. This paper presents two methodologies that extend the tools to analyze spatio-temporal drought development and characteristics us...

  6. Hydrological Response to the 2011 Drought in Texas Using Land Surface Modeling, Remote Sensing, and GRACE

    Science.gov (United States)

    Long, D.; Scanlon, B. R.; Longuevergne, L.

    2013-12-01

    Texas was subjected to the most extreme one-year drought on record in 2011, which had a tremendous impact on water resources statewide. This study aims to quantify evapotranspiration (ET) from land surface models (LSMs), remote sensing, and GRACE during the drought. Uncertainties in ET output from four LSMs, i.e., Noah, Mosaic, VIC, and SAC in NLDAS-2, two remote sensing-based products, i.e., MODIS and AVHRR, and GRACE-derived ET as a residual in the water budget (ET = P - R - ΔTWS) based on precipitation (P) from PRISM, monitored runoff (R), and total water storage (TWS) change from GRACE satellites were quantified using the three corner hat method that does not require a priori knowledge of the true value of ET. Water budgets were calculated using the traditional flux approach and a new storage approach in combination with the different ET products and GRACE TWS. The analyses were conducted using data from three river basins (humid - arid) primarily in Texas as case studies. Remote sensing-based ET shows markedly higher magnitudes during drought but significantly lower magnitudes at other times, particularly during wet periods than land surface model-based ET. Overestimation of ET during drought would result in overestimation of soil moisture depletion and much longer projected times for drought recovery. Uncertainties in ET are lowest in LSM ET (~5 mm/month), moderate in remote sensing MODIS- or AVHRR-based ET (10 - 15 mm/month), and highest in GRACE-based ET (20 - 30 mm/month). Uncertainties in total water storage changes from the water budget approach (ΔTWS = P-R-ET) are about half of uncertainties in GRACE-derived TWS changes for each of the basins. Future ET estimation should consider a hybrid approach that integrates LSM and satellite-based products to constrain uncertainties.

  7. Assessing Drought Impacts on Water Storage using GRACE Satellites and Regional Groundwater Modeling in the Central Valley of California

    Science.gov (United States)

    Scanlon, B. R.; Zhang, Z.; Save, H.; Faunt, C. C.; Dettinger, M. D.

    2015-12-01

    Increasing concerns about drought impacts on water resources in California underscores the need to better understand effects of drought on water storage and coping strategies. Here we use a new GRACE mascons solution with high spatial resolution (1 degree) developed at the Univ. of Texas Center for Space Research (CSR) and output from the most recent regional groundwater model developed by the U.S. Geological Survey to evaluate changes in water storage in response to recent droughts. We also extend the analysis of drought impacts on water storage back to the 1980s using modeling and monitoring data. The drought has been intensifying since 2012 with almost 50% of the state and 100% of the Central Valley under exceptional drought in 2015. Total water storage from GRACE data declined sharply during the current drought, similar to the rate of depletion during the previous drought in 2007 - 2009. However, only 45% average recovery between the two droughts results in a much greater cumulative impact of both droughts. The CSR GRACE Mascons data offer unprecedented spatial resolution with no leakage to the oceans and no requirement for signal restoration. Snow and reservoir storage declines contribute to the total water storage depletion estimated by GRACE with the residuals attributed to groundwater storage. Rates of groundwater storage depletion are consistent with the results of regional groundwater modeling in the Central Valley. Traditional approaches to coping with these climate extremes has focused on surface water reservoir storage; however, increasing conjunctive use of surface water and groundwater and storing excess water from wet periods in depleted aquifers is increasing in the Central Valley.

  8. 2-D Model Test Study of the Suape Breakwater, Brazil

    DEFF Research Database (Denmark)

    Andersen, Thomas Lykke; Burcharth, Hans F.; Sopavicius, A.;

    This report deals with a two-dimensional model test study of the extension of the breakwater in Suape, Brazil. One cross-section was tested for stability and overtopping in various sea conditions. The length scale used for the model tests was 1:35. Unless otherwise specified all values given...

  9. Future discharge drought across climate regions around the world modelled with a synthetic hydrological modelling approach forced by three general circulation models

    OpenAIRE

    N. Wanders; Lanen, van, H.A.J.

    2015-01-01

    Hydrological drought characteristics (drought in groundwater and streamflow) likely will change in the 21st century as a result of climate change. The magnitude and directionality of these changes and their dependency on climatology and catchment characteristics, however, is uncertain. In this study a conceptual hydrological model was forced by downscaled and bias-corrected outcome from three general circulation models for the SRES A2 emission scenario (GCM forced models), and the WATCH Forci...

  10. Modelling drought-induced dieback of Aleppo pine at the arid timberline

    Science.gov (United States)

    Wingate, Lisa; Preisler, Yakir; Bert, Didier; Rotenberg, Eyal; Yakir, Dan; Maseyk, Kadmiel; Ogee, Jerome

    2016-04-01

    During the mid 1960's an ambitious afforestation programme was initiated in the Negev desert of Israel. After five decades enduring harsh growing conditions, the Aleppo pine forest of Yatir is now exhibiting signs of 'drought-induced' dieback. Since 2010, 5-10% of the entire Yatir population have died, however the pattern of mortality is extremely patchy with some areas exhibiting >80% mortality whilst others display none. In this presentation, we reflect on historic climatic and edaphic conditions that have triggered this landscape mosaic of survival and mortality and how physiological and hydraulic traits vary within this patchwork. In addition, we explore how these pine trees have responded physiologically over recent years (1996-2010) to a series of severe drought events using a combined approach that brings together micrometeorological, dendro-isotopic and dendro-climatological datasets alongside process-based modelling. In particular the dataset trends were investigated with the isotope-enabled ecosystem model MuSICA to explore the consequences of subsequent droughts and embolism on modelled carbohydrate and water pool dynamics and their impact on carbon allocation and ecosystem function.

  11. The US CLIVAR Working Group on Drought: A Multi-Model Assessment of the Impact of SST Anomalies on Regional Drought

    Science.gov (United States)

    Schubert, Siegfried

    2008-01-01

    The US CLIVAR working group on drought recently initiated a series of global climate model simulations forced with idealized SST anomaly patterns, designed to address a number of uncertainties regarding the impact of SST forcing and the role of land-atmosphere feedbacks on regional drought. Specific questions that the runs are designed to address include: What are mechanisms that maintain drought across the seasonal cycle and from one year to the next. What is the role of the land? What is the role of the different ocean basins, including the impact of EL Nino/Southern Oscillation (ENSO), the Pacific Decadal Oscillation (PDO), the Atlantic Multi-decadal Oscillation (AMO), and warming trends in the global oceans? The runs were done with several global atmospheric models including NASA/NSIPP-1, NCEP/GFS, GFDL/AM2, and NCAR CCM3 and CAM3. In addition, runs were done with the NCEP CFS (coupled atmosphere-ocean) model by employing a novel adjustment technique to nudge the coupled model towards the imposed SST forcing patterns. This talk provides an overview of the experiments and some initial results.

  12. Effects of Severe Floods and Droughts on Wildlife of the Pantanal Wetland (Brazil)—A Review

    OpenAIRE

    Cleber J. R. Alho; Silva, João S. V.

    2012-01-01

    Simple Summary The Pantanal is a wetland in the center of South America, (140,000 km² in Brazil), in the Upper Paraguay River Basin. Because of its diverse and abundant wildlife, it is recognized as one of the most important freshwater ecosystems in the world. Many endangered species occur there, including jaguar; waterfowl are exceptionally abundant. Relief varies between the low, and flat floodplain, and the surrounding non-flooded plateau areas. Rainfall shows inter-annual variability, inf...

  13. Evaluation of a Model-Based Groundwater Drought Indicator in the Conterminous U.S.

    Science.gov (United States)

    Li, Bailing; Rodell, Matthew

    2015-01-01

    Monitoring groundwater drought using land surface models is a valuable alternative given the current lack of systematic in situ measurements at continental and global scales and the low resolution of current remote sensing based groundwater data. However, uncertainties inherent to land surface models may impede drought detection, and thus should be assessed using independent data sources. In this study, we evaluated a groundwater drought index (GWI) derived from monthly groundwater storage output from the Catchment Land Surface Model (CLSM) using a GWI similarly derived from in situ groundwater observations. Groundwater observations were obtained from unconfined or semi-confined aquifers in eight regions of the central and northeastern U.S. Regional average GWI derived from CLSM exhibited strong correlation with that from observation wells, with correlation coefficients between 0.43 and 0.92. GWI from both in situ data and CLSM was generally better correlated with the Standard Precipitation Index (SPI) at 12 and 24 month timescales than at shorter timescales, but it varied depending on climate conditions. The correlation between CLSM derived GWI and SPI generally decreases with increasing depth to the water table, which in turn depends on both bedrock depth (a CLSM parameter) and mean annual precipitation. The persistence of CLSM derived GWI is spatially varied and again shows a strong influence of depth to groundwater. CLSM derived GWI generally persists longer than GWI derived from in situ data, due at least in part to the inability of coarse model inputs to capture high frequency meteorological variability at local scales. The study also showed that groundwater can have a significant impact on soil moisture persistence where the water table is shallow. Soil moisture persistence was estimated to be longer in the eastern U.S. than in the west, in contrast to previous findings that were based on models that did not represent groundwater. Assimilation of terrestrial

  14. Flood and drought hydrologic monitoring: the role of model parameter uncertainty

    Directory of Open Access Journals (Sweden)

    N. W. Chaney

    2015-02-01

    Full Text Available Land surface modeling, in conjunction with numerical weather forecasting and satellite remote sensing, is playing an increasing role in global monitoring and prediction of extreme hydrologic events (i.e., floods and droughts. However, uncertainties in the meteorological forcings, model structure, and parameter identifiability limit the reliability of model predictions. This study focuses on the latter by assessing two potential weaknesses that emerge due to limitations in our global runoff observations: (1 the limits of identifying model parameters at coarser time scales than those at which the extreme events occur, and (2 the negative impacts of not properly accounting for model parameter equifinality in the predictions of extreme events. To address these challenges, petascale parallel computing is used to perform the first global-scale, 10 000 member ensemble-based evaluation of plausible model parameters using the VIC (Variable Infiltration Capacity land surface model, aiming to characterize the impact of parameter identifiability on the uncertainty in flood and drought predictions. Additionally, VIC's global-scale parametric sensitivities are assessed at the annual, monthly, and daily timescales to determine whether coarse-timescale observations can properly constrain extreme events. Global and climate type results indicate that parameter uncertainty remains an important concern for predicting extreme events even after applying monthly and annual constraints to the ensemble, suggesting a need for more accurate prior distributions of the model parameters and improved observations. This study contributes a comprehensive evaluation of land surface modeling for global flood and drought monitoring and suggests paths forward to overcome the challenges posed by parameter uncertainty.

  15. Brazil.

    Science.gov (United States)

    1985-09-01

    Brazil's population in 1985 was 135 million, with an annual growth rate (1982) of 2.3%. The infant mortality rate (1981) was 92/1000, and life expectancy stood at 62.8 years. 76% of the adult population was literate. Brazil is a federal republic which recognizes 5 political parties. 55% of the population is Portuguese, Italian, German, Japanese, African, or American Indian; 38% is white. Of the work force of 50 million, 35% are engaged in agriculture, 25% work in industry, and 40% are employed in services. Trade union membership totals 6 million. The agricultural sector accounts for 12% of the GDP and 40% of exports. Brazil is largely self-sufficient in terms of food. The GDP was US$218 billion in 1984, with an annual growth rate of 4%. Per capita GDP was US$1645. Brazil's power, transportation, and communications systems have improved greatly in recent years, providing a base for economic development. High inflation rates have been a persistent problem.

  16. Large net CO2 loss from a grass-dominated tropical savanna in south-central Brazil in response to seasonal and interannual drought

    Science.gov (United States)

    Vourlitis, G. L.; Arruda, P. H. Z. D.; Santanna, F. B.; Pinto-Jr, O. B.; Lobo, F. D. A.; Nogueira, J. D. S.

    2015-12-01

    The savanna vegetation of Brazil (Cerrado), accounts for 20-25% of the total land cover of Brazil; however, little is still known about the spatial and temporal variations in mass and energy exchange of Cerrado. Our goal was to evaluate the seasonal and interannual variations in CO2 exchange for a grass-dominated Cerrado stand over a three-year period and to elucidate the biophysical controls on CO2 exchange. We hypothesized that soil water availability (SWA) would be a key control over the direction and magnitude of CO2 exchange. Field measurements were conducted Mar 2011- Dec 2013 at the Fazenda Miranda, located 15 km SSE of Cuiabá, Mato Grosso, Brazil. Net CO2 (NEE), latent, and sensible heat fluxes were quantified using eddy covariance. NEE was strongly affected by SWA; however, other biophysical variables were also important in controlling temporal patterns of CO2 exchange. Step-wise regression revealed four variables that explained 69% of the seasonal and interannual variation in gross primary production (GPP), and GPP increased as a function of the MODIS enhanced vegetation index (EVI), solar radiation (Rs), and soil water content (θs) but declined as a function of the vapor pressure deficit (VPD). Similarly, stepwise regression identified six variables that explained 78% of the variance in ecosystem respiration (Reco), and Reco was positively related to air temperature, the EVI, Rs, and θs and negatively correlated with VPD and precipitation. Consistent net CO2 losses during the dry season caused a cumulative net CO2 loss of 840 gC/m2 over the 3 year study period. Periods of accumulated net loss occurred when the difference between precipitation and evapotranspiration declined, which typically occurred between March and November of each year. The annual net CO2 losses are in contrast to rates of NEE reported for other cerrado ecosystems, and the differences between our results and those reported for other cerrado ecosystems may reflect the low average

  17. ASSESSMENT OF EARLY SEASON AGRICULTURAL DROUGHT THROUGH LAND SURFACE WATER INDEX (LSWI) AND SOIL WATER BALANCE MODEL

    OpenAIRE

    K. Chandrasekar; Sesha Sai, M. V. R.; G. Behera

    2012-01-01

    An attempt was made to address the early season agriculture drought, by monitoring the surface soil wetness during 2010 cropping seasons in the states of Andhra Pradesh and Tamil Nadu. Short Wave Infrared (SWIR) based Land Surface Water Index (LSWI) and Soil Water Balance (SWB) model using inputs from remote sensing and ancillary data were used to monitor early season agriculture drought. During the crop season, investigation was made on LSWI characteristics and its response to the rainfall. ...

  18. Do maize models capture the impacts of heat and drought stresses on yield? Using algorithm ensembles to identify successful approaches.

    Science.gov (United States)

    Jin, Zhenong; Zhuang, Qianlai; Tan, Zeli; Dukes, Jeffrey S; Zheng, Bangyou; Melillo, Jerry M

    2016-09-01

    Stresses from heat and drought are expected to increasingly suppress crop yields, but the degree to which current models can represent these effects is uncertain. Here we evaluate the algorithms that determine impacts of heat and drought stress on maize in 16 major maize models by incorporating these algorithms into a standard model, the Agricultural Production Systems sIMulator (APSIM), and running an ensemble of simulations. Although both daily mean temperature and daylight temperature are common choice of forcing heat stress algorithms, current parameterizations in most models favor the use of daylight temperature even though the algorithm was designed for daily mean temperature. Different drought algorithms (i.e., a function of soil water content, of soil water supply to demand ratio, and of actual to potential transpiration ratio) simulated considerably different patterns of water shortage over the growing season, but nonetheless predicted similar decreases in annual yield. Using the selected combination of algorithms, our simulations show that maize yield reduction was more sensitive to drought stress than to heat stress for the US Midwest since the 1980s, and this pattern will continue under future scenarios; the influence of excessive heat will become increasingly prominent by the late 21st century. Our review of algorithms in 16 crop models suggests that the impacts of heat and drought stress on plant yield can be best described by crop models that: (i) incorporate event-based descriptions of heat and drought stress, (ii) consider the effects of nighttime warming, and (iii) coordinate the interactions among multiple stresses. Our study identifies the proficiency with which different model formulations capture the impacts of heat and drought stress on maize biomass and yield production. The framework presented here can be applied to other modeled processes and used to improve yield predictions of other crops with a wide variety of crop models. PMID:27251794

  19. Simulating the 2012 High Plains Drought Using Three Single Column Models (SCM)

    Science.gov (United States)

    Medina, I. D.; Baker, I. T.; Denning, S.; Dazlich, D. A.

    2015-12-01

    The impact of changes in the frequency and severity of drought on fresh water sustainability is a great concern for many regions of the world. One such location is the High Plains, where the local economy is primarily driven by fresh water withdrawals from the Ogallala Aquifer, which accounts for approximately 30% of total irrigation withdrawals from all U.S. aquifers combined. Modeling studies that focus on the feedback mechanisms that control the climate and eco-hydrology during times of drought are limited, and have used conventional General Circulation Models (GCMs) with grid length scales ranging from one hundred to several hundred kilometers. Additionally, these models utilize crude statistical parameterizations of cloud processes for estimating sub-grid fluxes of heat and moisture and have a poor representation of land surface heterogeneity. For this research, we focus on the 2012 High Plains drought and perform numerical simulations using three single column model (SCM) versions of BUGS5 (Colorado State University (CSU) GCM coupled to the Simple Biosphere Model (SiB3)). In the first version of BUGS5, the model is used in its standard bulk setting (single atmospheric column coupled to a single instance of SiB3), secondly, the Super-Parameterized Community Atmospheric Model (SP-CAM), a cloud resolving model (CRM) (CRM consists of 32 atmospheric columns), replaces the single CSU GCM atmospheric parameterization and is coupled to a single instance of SiB3, and for the third version of BUGS5, an instance of SiB3 is coupled to each CRM column of the SP-CAM (32 CRM columns coupled to 32 instances of SiB3). To assess the physical realism of the land-atmosphere feedbacks simulated by all three versions of BUGS5, differences in simulated energy and moisture fluxes are computed between the 2011 and 2012 period and are compared to those calculated using observational data from the AmeriFlux Tower Network for the same period at the ARM Site in Lamont, OK. This research

  20. A multi-model and multi-index evaluation of drought characteristics in the 21st century

    Science.gov (United States)

    Touma, Danielle; Ashfaq, Moetasim; Nayak, Munir A.; Kao, Shih-Chieh; Diffenbaugh, Noah S.

    2015-07-01

    Drought is a natural hazard that can have severe and long-lasting impacts on natural and human systems. Although increases in global greenhouse forcing are expected to change the characteristics and impacts of drought in the 21st century, there remains persistent uncertainty about how changes in temperature, precipitation and soil moisture will interact to shape the magnitude - and in some cases direction - of drought in different areas of the globe. Using data from 15 global climate models archived in the Coupled Model Intercomparison Project (CMIP5), we assess the likelihood of changes in the spatial extent, duration and number of occurrences of four drought indices: the Standardized Precipitation Index (SPI), the Standardized Runoff Index (SRI), the Standardized Precipitation-Evapotranspiration Index (SPEI) and the Supply-Demand Drought Index (SDDI). We compare these characteristics in two future periods (2010-2054 and 2055-2099) of the Representative Concentration Pathway 8.5 (RCP8.5). We find increases from the baseline period (1961-2005) in the spatial extent, duration and occurrence of "exceptional" drought in subtropical and tropical regions, with many regions showing an increase in both the occurrence and duration. There is strong agreement on the sign of these changes among the individual climate models, although some regions do exhibit substantial uncertainty in the magnitude of change. The changes in SPEI and SDDI characteristics are stronger than the changes in SPI and SRI due to the greater influence of temperature changes in the SPEI and SDDI indices. In particular, we see a robust permanent emergence of the spatial extent of SDDI from the baseline variability in West, East and Saharan Africa as early as 2020 and by 2080 in several other subtropical and tropical regions. The increasing likelihood of exceptional drought identified in our results suggests increasing risk of drought-related stresses for natural and human systems should greenhouse gas

  1. Modelling soil water content variations under drought stress on soil column cropped with winter wheat

    Directory of Open Access Journals (Sweden)

    Csorba Szilveszter

    2014-12-01

    Full Text Available Mathematical models are effective tools for evaluating the impact of predicted climate change on agricultural production, but it is difficult to test their applicability to future weather conditions. We applied the SWAP model to assess its applicability to climate conditions, differing from those, for which the model was developed. We used a database obtained from a winter wheat drought stress experiment. Winter wheat was grown in six soil columns, three having optimal water supply (NS, while three were kept under drought-stressed conditions (S. The SWAP model was successfully calibrated against measured values of potential evapotranspiration (PET, potential evaporation (PE and total amount of water (TSW in the soil columns. The Nash-Sutcliffe model efficiency coefficient (N-S for TWS for the stressed columns was 0.92. For the NS treatment, we applied temporally variable soil hydraulic properties because of soil consolidation caused by regular irrigation. This approach improved the N-S values for the wetting-drying cycle from -1.77 to 0.54. We concluded that the model could be used for assessing the effects of climate change on soil water regime. Our results indicate that soil water balance studies should put more focus on the time variability of structuredependent soil properties.

  2. SPI drought class prediction using log-linear models applied to wet and dry seasons

    Science.gov (United States)

    Moreira, Elsa E.

    2016-08-01

    A log-linear modelling for 3-dimensional contingency tables was used with categorical time series of SPI drought class transitions for prediction of monthly drought severity. Standardized Precipitation Index (SPI) time series in 12- and 6-month time scales were computed for 10 precipitation time series relative to GPCC datasets with 2.5° spatial resolution located over Portugal and with 112 years length (1902-2014). The aim was modelling two-month step class transitions for the wet and dry seasons of the year and then obtain probability ratios - Odds - as well as their respective confidence intervals to estimate how probable a transition is compared to another. The prediction results produced by the modelling applied to wet and dry season separately, for the 6- and the 12-month SPI time scale, were compared with the results produced by the same modelling without the split, using skill scores computed for the entire time series length. Results point to good prediction performances ranging from 70 to 80% in the percentage of corrects (PC) and 50-70% in the Heidke skill score (HSS), with the highest scores obtained when the modelling is applied to the SPI12. The adding up of the wet and dry seasons introduced in the modelling brought improvements in the predictions, of about 0.9-4% in the PC and 1.3-6.8% in the HSS, being the highest improvements obtained in the SPI6 application.

  3. On the utility of land surface models for agricultural drought monitoring

    Directory of Open Access Journals (Sweden)

    W. T. Crow

    2012-04-01

    Full Text Available The lagged rank cross-correlation between model-derived root-zone soil moisture estimates and remotely-sensed vegetation indices (VI is examined between January 2000 and December 2010 to quantify the skill of various soil moisture models for agricultural drought monitoring. Examined modeling strategies range from a simple antecedent precipitation index to the application of modern land surface models (LSMs based on complex water and energy balance formations. A quasi-global evaluation of lagged VI/soil moisture cross-correlation suggests, when averaged in bulk across the annual cycle, little or no added skill (<5% in relative terms is associated with applying modern LSMs to off-line agricultural drought monitoring relative to simple accounting procedures based solely on observed precipitation accumulations. However, slightly larger amounts of added skill (5–15% in relative terms are identified when focusing exclusively on the extra-tropical growing season and/or utilizing soil moisture values acquired by averaging across a multi-model ensemble.

  4. Validating modeled soil moisture with in-situ data for agricultural drought monitoring in West Africa

    Science.gov (United States)

    McNally, A.; Yatheendradas, S.; Jayanthi, H.; Funk, C. C.; Peters-Lidard, C. D.

    2011-12-01

    The declaration of famine in Somalia on July 21, 2011 highlights the need for regional hydroclimate analysis at a scale that is relevant for agropastoral drought monitoring. A particularly critical and robust component of such a drought monitoring system is a land surface model (LSM). We are currently enhancing the Famine Early Warning Systems Network (FEWS NET) monitoring activities by configuring a custom instance of NASA's Land Information System (LIS) called the FEWS NET Land Data Assimilation System (FLDAS). Using the LIS Noah LSM, in-situ measurements, and remotely sensed data, we focus on the following question: How can Noah be best parameterized to accurately simulate hydroclimate variables associated with crop performance? Parameter value testing and validation is done by comparing modeled soil moisture against fortuitously available in-situ soil moisture observations in the West Africa. Direct testing and application of the FLDAS over African agropastoral locations is subject to some issues: [1] In many regions that are vulnerable to food insecurity ground based measurements of precipitation, evapotranspiration and soil moisture are sparse or non-existent, [2] standard landcover classes (e.g., the University of Maryland 5 km dataset), do not include representations of specific agricultural crops with relevant parameter values, and phenologies representing their growth stages from the planting date and [3] physically based land surface models and remote sensing rain data might still need to be calibrated or bias-corrected for the regions of interest. This research aims to address these issues by focusing on sites in the West African countries of Mali, Niger, and Benin where in-situ rainfall and soil moisture measurements are available from the African Monsoon Multidisciplinary Analysis (AMMA). Preliminary results from model experiments over Southern Malawi, validated with Normalized Difference Vegetation Index (NDVI) and maize yield data, show that the

  5. Remote Sensing of Grass Response to Drought Stress Using Spectroscopic Techniques and Canopy Reflectance Model Inversion

    Directory of Open Access Journals (Sweden)

    Bagher Bayat

    2016-07-01

    Full Text Available The aim of this study was to follow the response to drought stress in a Poa pratensis canopy exposed to various levels of soil moisture deficit. We tracked the changes in the canopy reflectance (450–2450 nm and retrieved vegetation properties (Leaf Area Index (LAI, leaf chlorophyll content (Cab, leaf water content (Cw, leaf dry matter content (Cdm and senescent material (Cs during a drought episode. Spectroscopic techniques and radiative transfer model (RTM inversion were employed to monitor the gradual manifestation of drought effects in a laboratory setting. Plots of 21 cm × 14.5 cm surface area with Poa pratensis plants that formed a closed canopy were divided into a well-watered control group and a group subjected to water stress for 36 days. In a regular weekly schedule, canopy reflectance and destructive measurements of LAI and Cab were taken. Spectral analysis indicated the first sign of stress after 4–5 days from the start of the experiment near the water absorption bands (at 1930 nm, 1440 nm and in the red (at 675 nm. Spectroscopic techniques revealed plant stress up to 6 days earlier than visual inspection. Of the water stress-related vegetation indices, the response of Normalized Difference Water Index (NDWI_1241 and Normalized Photochemical Reflectance Index (PRI_norm were significantly stronger in the stressed group than the control. To observe the effects of stress on grass properties during the drought episode, we used the RTMo (RTM of solar and sky radiation model inversion by means of an iterative optimization approach. The performance of the model inversion was assessed by calculating R2 and the Normalized Root Mean Square Error (RMSE between retrieved and measured LAI (R2 = 0.87, NRMSE = 0.18 and Cab (R2 = 0.74, NRMSE = 0.15. All parameters retrieved by model inversion co-varied with soil moisture deficit. However, the first strong sign of water stress on the retrieved grass properties was detected as a change of Cw

  6. Drought: A comprehensive R package for drought monitoring, prediction and analysis

    Science.gov (United States)

    Hao, Zengchao; Hao, Fanghua; Singh, Vijay P.; Cheng, Hongguang

    2015-04-01

    Drought may impose serious challenges to human societies and ecosystems. Due to complicated causing effects and wide impacts, a universally accepted definition of drought does not exist. The drought indicator is commonly used to characterize drought properties such as duration or severity. Various drought indicators have been developed in the past few decades for the monitoring of a certain aspect of drought condition along with the development of multivariate drought indices for drought characterizations from multiple sources or hydro-climatic variables. Reliable drought prediction with suitable drought indicators is critical to the drought preparedness plan to reduce potential drought impacts. In addition, drought analysis to quantify the risk of drought properties would provide useful information for operation drought managements. The drought monitoring, prediction and risk analysis are important components in drought modeling and assessments. In this study, a comprehensive R package "drought" is developed to aid the drought monitoring, prediction and risk analysis (available from R-Forge and CRAN soon). The computation of a suite of univariate and multivariate drought indices that integrate drought information from various sources such as precipitation, temperature, soil moisture, and runoff is available in the drought monitoring component in the package. The drought prediction/forecasting component consists of statistical drought predictions to enhance the drought early warning for decision makings. Analysis of drought properties such as duration and severity is also provided in this package for drought risk assessments. Based on this package, a drought monitoring and prediction/forecasting system is under development as a decision supporting tool. The package will be provided freely to the public to aid the drought modeling and assessment for researchers and practitioners.

  7. Seasonal Drought Prediction in East Africa: Can National Multi-Model Ensemble Forecasts Help?

    Science.gov (United States)

    Shukla, Shraddhanand; Roberts, J. B.; Funk, Christopher; Robertson, F. R.; Hoell, Andrew

    2015-01-01

    The increasing food and water demands of East Africa's growing population are stressing the region's inconsistent water resources and rain-fed agriculture. As recently as in 2011 part of this region underwent one of the worst famine events in its history. Timely and skillful drought forecasts at seasonal scale for this region can inform better water and agro-pastoral management decisions, support optimal allocation of the region's water resources, and mitigate socio-economic losses incurred by droughts. However seasonal drought prediction in this region faces several challenges. Lack of skillful seasonal rainfall forecasts; the focus of this presentation, is one of those major challenges. In the past few decades, major strides have been taken towards improvement of seasonal scale dynamical climate forecasts. The National Centers for Environmental Prediction's (NCEP) National Multi-model Ensemble (NMME) is one such state-of-the-art dynamical climate forecast system. The NMME incorporates climate forecasts from 6+ fully coupled dynamical models resulting in 100+ ensemble member forecasts. Recent studies have indicated that in general NMME offers improvement over forecasts from any single model. However thus far the skill of NMME for forecasting rainfall in a vulnerable region like the East Africa has been unexplored. In this presentation we report findings of a comprehensive analysis that examines the strength and weakness of NMME in forecasting rainfall at seasonal scale in East Africa for all three of the prominent seasons for the region. (i.e. March-April-May, July-August-September and October-November- December). Simultaneously we also describe hybrid approaches; that combine statistical approaches with NMME forecasts; to improve rainfall forecast skill in the region when raw NMME forecasts lack in skill.

  8. Modelling economic impacts of deficit irrigated maize in Brazil with consideration of different rainfall regimes

    OpenAIRE

    Rodrigues, Gonçalo C.; Martins, Juliano D.; Silva, Francisco G. da; Carlesso, Reimar; L. S. Pereira

    2013-01-01

    Deficit irrigation is often required to cope with droughts and limited water availability. However, to select an appropriate irrigation management, it is necessary to assess when economic impacts of deficit irrigation are acceptable. Thus, the main goal of this study was to evaluate economic water productivity for maize submitted to various levels of water deficits and different irrigation systems. The study was based on two different experiments conducted in Southern Brazil, o...

  9. Assessing the risk persistent drought using climate model simulations and paleoclimate data

    Science.gov (United States)

    Ault, Toby R.; Cole, Julia E.; Overpeck, Jonathan T.; Pederson, Gregory T.; Meko, David M.

    2014-01-01

    Projected changes in global rainfall patterns will likely alter water supplies and ecosystems in semiarid regions during the coming century. Instrumental and paleoclimate data indicate that natural hydroclimate fluctuations tend to be more energetic at low (multidecadal to multicentury) than at high (interannual) frequencies. State-of-the-art global climate models do not capture this characteristic of hydroclimate variability, suggesting that the models underestimate the risk of future persistent droughts. Methods are developed here for assessing the risk of such events in the coming century using climate model projections as well as observational (paleoclimate) information. Where instrumental and paleoclimate data are reliable, these methods may provide a more complete view of prolonged drought risk. In the U.S. Southwest, for instance, state-of-the-art climate model projections suggest the risk of a decade-scale megadrought in the coming century is less than 50%; the analysis herein suggests that the risk is at least 80%, and may be higher than 90% in certain areas. The likelihood of longer-lived events (>35 yr) is between 20% and 50%, and the risk of an unprecedented 50-yr megadrought is nonnegligible under the most severe warming scenario (5%–10%). These findings are important to consider as adaptation and mitigation strategies are developed to cope with regional impacts of climate change, where population growth is high and multidecadal megadrought—worse than anything seen during the last 2000 years—would pose unprecedented challenges to water resources in the region.

  10. Solar Radiation Estimated Through Mesoscale Atmospheric Modeling over Northeast Brazil

    Science.gov (United States)

    de Menezes Neto, Otacilio Leandro; Costa, Alexandre Araújo; Ramalho, Fernando Pinto; de Maria, Paulo Henrique Santiago

    2009-03-01

    The use of renewable energy sources, like solar, wind and biomass is rapidly increasing in recent years, with solar radiation as a particularly abundant energy source over Northeast Brazil. A proper quantitative knowledge of the incoming solar radiation is of great importance for energy planning in Brazil, serving as basis for developing future projects of photovoltaic power plants and solar energy exploitation. This work presents a methodology for mapping the incoming solar radiation at ground level for Northeast Brazil, using a mesoscale atmospheric model (Regional Atmospheric Modeling System—RAMS), calibrated and validated using data from the network of automatic surface stations from the State Foundation for Meteorology and Water Resources from Ceará (Fundação Cearense de Meteorologia e Recursos Hídricos- FUNCEME). The results showed that the model exhibits systematic errors, overestimating surface radiation, but that, after the proper statistical corrections, using a relationship between the model-predicted cloud fraction, the ground-level observed solar radiation and the incoming solar radiation estimated at the top of the atmosphere, a correlation of 0.92 with a confidence interval of 13.5 W/m2 is found for monthly data. Using this methodology, we found an estimate for annual average incoming solar radiation over Ceará of 215 W/m2 (maximum in October: 260 W/m2).

  11. Chance-Constrained Model for Real-Time Reservoir Operation Using Drought Duration Curve

    Science.gov (United States)

    Takeuchi, Kuniyoshi

    1986-04-01

    The seasonal drought duration curve (SDDC) ƒβ (m|τ) is defined as a deterministic equivalent of an average streamflow over an m-day period starting from date τ with probability of failure being β. This curve provides an estimate of a sum of inflows over m days starting from date τ in a T ( = 1/β)-year drought. The reservoir system considered is a single-purpose reservoir already in service. The demand pattern is predetermined, and the percentage of deficit in meeting the demand (supply cut) is left to operators' judgement. A chance-constrained model was developed for such a system. The model determined the percentage of supply cut on date τ in such the way that the probability of exhaustion of reservoir storage Sτ+m at the beginning of date τ+m was maintained less than a given constant βm for all 1 ≤ m ≤ M, i.e., Prob {Sτ+m ≤ 0} ≤ βm, m = 1, 2, …, M, where M is the number of days in the future to be considered to make a current decision on date τ, and βm are a given set of allowable exhaustion probability selected from an indifferent preference curve between reservoir exhaustion probability β and anticipated time to its occurrence, m. The reservoir operation rule thus developed was named as DDC rule curves and demonstrated satisfactorily operational through a simulation study of the Fukuoka drought case during 1978-1979.

  12. Global Climate Model Simulated Hydrologic Droughts and Floods in the Nelson-Churchill Watershed

    Science.gov (United States)

    Vieira, M. J. F.; Stadnyk, T. A.; Koenig, K. A.

    2014-12-01

    There is uncertainty surrounding the duration, magnitude and frequency of historical hydroclimatic extremes such as hydrologic droughts and floods prior to the observed record. In regions where paleoclimatic studies are less reliable, Global Climate Models (GCMs) can provide useful information about past hydroclimatic conditions. This study evaluates the use of Coupled Model Intercomparison Project 5 (CMIP5) GCMs to enhance the understanding of historical droughts and floods across the Canadian Prairie region in the Nelson-Churchill Watershed (NCW). The NCW is approximately 1.4 million km2 in size and drains into Hudson Bay in Northern Manitoba, Canada. One hundred years of observed hydrologic records show extended dry and wet periods in this region; however paleoclimatic studies suggest that longer, more severe droughts have occurred in the past. In Manitoba, where hydropower is the primary source of electricity, droughts are of particular interest as they are important for future resource planning. Twenty-three GCMs with daily runoff are evaluated using 16 metrics for skill in reproducing historic annual runoff patterns. A common 56-year historic period of 1950-2005 is used for this evaluation to capture wet and dry periods. GCM runoff is then routed at a grid resolution of 0.25° using the WATFLOOD hydrological model storage-routing algorithm to develop streamflow scenarios. Reservoir operation is naturalized and a consistent temperature scenario is used to determine ice-on and ice-off conditions. These streamflow simulations are compared with the historic record to remove bias using quantile mapping of empirical distribution functions. GCM runoff data from pre-industrial and future projection experiments are also bias corrected to obtain extended streamflow simulations. GCM streamflow simulations of more than 650 years include a stationary (pre-industrial) period and future periods forced by radiative forcing scenarios. Quantile mapping adjusts for magnitude

  13. Coupling a water balance model with forest inventory data to predict drought stress : the role of forest structural changes vs. climate changes

    OpenAIRE

    Càceres, Miquel de; MARTÍNEZ VILALTA, Jordi; Coll, Lluís; Llorens García, Pilar; Casals, Pere; Poyatos López, Rafael; Pausas, Juli G.; Brotons Alabau, Lluís

    2015-01-01

    Mechanistic water balance models can be used to predict soil moisture dynamics and drought stress in individual forest stands. Predicting current and future levels of plant drought stress is important not only at the local scale, but also at larger, landscape to regional, scales, because these are the management scales at which adaptation and mitigation strategies are implemented. To obtain reliable predictions of soil moisture and plant drought stress over large extents, water balance models...

  14. Future changes in drought characteristics over South Korea using multi regional climate models with the standardized precipitation index

    Science.gov (United States)

    Choi, Yeon-Woo; Ahn, Joong-Bae; Suh, Myoung-Seok; Cha, Dong-Hyun; Lee, Dong-Kyou; Hong, Song-You; Min, Seung-Ki; Park, Seong-Chan; Kang, Hyun-Suk

    2016-05-01

    In this study, the projection of future drought conditions is estimated over South Korea based on the latest and most advanced sets of regional climate model simulations under the Representative Concentration Pathway (RCP4.5 and RCP8.5) scenarios, within the context of the national downscaling project of the Republic of Korea. The five Regional Climate Models (RCMs) are used to produce climate-change simulations around the Korean Peninsula and to estimate the uncertainty associated with these simulations. The horizontal resolution of each RCM is 12.5 km and model simulations are available for historical (1981-2010) and future (2021-2100) periods under forcing from the RCP4.5 and RCP8.5 scenarios. To assess the characteristics of drought on multiple time scales in the future, we use Standardized Precipitation Indices for 1-month (SPI- 1), 6-month (SPI-6) and 12-month (SPI-12). The number of drought months in the future is shown to be characterized by strong variability, with both increasing and decreasing trends among the scenarios. In particular, the number of drought months over South Korea is projected to increase (decrease) for the period 2041-2070 in the RCP8.5 (RCP4.5) scenario and increase (decrease) for the period 2071-2100 in the RCP4.5 (RCP8.5) scenario. In addition, the percentage area under any drought condition is overall projected to gradually decrease over South Korea during the entire future period, with the exception of SPI-1 in the RCP4.5 scenario. Particularly, the drought areas for SPI-1 in the RCP4.5 scenario show weakly positive long-term trend. Otherwise, future changes in drought areas for SPI-6 and SPI-12 have a marked downward trend under the two RCP scenarios.

  15. Using plant growth modeling to analyse C source-sink relations under drought: inter and intra specific comparison

    Directory of Open Access Journals (Sweden)

    Benoit ePallas

    2013-11-01

    Full Text Available The ability to assimilate C and allocate NSC (non structural carbohydrates to the most appropriate organs is crucial to maximize plant ecological or agronomic performance. Such C source and sink activities are differentially affected by environmental constraints. Under drought, plant growth is generally more sink than source limited as organ expansion or appearance rate is earlier and stronger affected than C assimilation. This favors plant survival and recovery but not always agronomic performance as NSC are stored rather than used for growth due to a modified metabolism in source and sink leaves. Such interactions between plant C and water balance are complex and plant modeling can help analyzing their impact on plant phenotype. This paper addresses the impact of trade-offs between C sink and source activities and plant production under drought, combining experimental and modeling approaches. Two contrasted monocotyledonous species (rice, oil palm were studied. Experimentally, the sink limitation of plant growth under moderate drought was confirmed as well as the modifications in NSC metabolism in source and sink organs. Under severe stress, when C source became limiting, plant NSC concentration decreased. Two plant models dedicated to oil palm and rice morphogenesis were used to perform a sensitivity analysis and further explore how to optimize C sink and source drought sensitivity to maximize plant growth. Modeling results highlighted that optimal drought sensitivity depends both on drought type and species and that modeling is a great opportunity to analyse such complex processes. Further modeling needs and more generally the challenge of using models to support complex trait breeding are discussed.

  16. Suitability of modelled and remotely sensed essential climate variables for monitoring Euro-Mediterranean droughts

    Science.gov (United States)

    Szczypta, C.; Calvet, J.-C.; Maignan, F.; Dorigo, W.; Baret, F.; Ciais, P.

    2014-05-01

    Two new remotely sensed leaf area index (LAI) and surface soil moisture (SSM) satellite-derived products are compared with two sets of simulations of the ORganizing Carbon and Hydrology In Dynamic EcosystEms (ORCHIDEE) and Interactions between Soil, Biosphere and Atmosphere, CO2-reactive (ISBA-A-gs) land surface models. We analyse the interannual variability over the period 1991-2008. The leaf onset and the length of the vegetation growing period (LGP) are derived from both the satellite-derived LAI and modelled LAI. The LGP values produced by the photosynthesis-driven phenology model of ISBA-A-gs are closer to the satellite-derived LAI and LGP than those produced by ORCHIDEE. In the latter, the phenology is based on a growing degree day model for leaf onset, and on both climatic conditions and leaf life span for senescence. Further, the interannual variability of LAI is better captured by ISBA-A-gs than by ORCHIDEE. In order to investigate how recent droughts affected vegetation over the Euro-Mediterranean area, a case study addressing the summer 2003 drought is presented. It shows a relatively good agreement of the modelled LAI anomalies with the observations, but the two models underestimate plant regrowth in the autumn. A better representation of the root-zone soil moisture profile could improve the simulations of both models. The satellite-derived SSM is compared with SSM simulations of ISBA-A-gs only, as ORCHIDEE has no explicit representation of SSM. Overall, the ISBA-A-gs simulations of SSM agree well with the satellite-derived SSM and are used to detect regions where the satellite-derived product could be improved. Finally, a correspondence is found between the interannual variability of detrended SSM and LAI. The predictability of LAI is less pronounced using remote sensing observations than using simulated variables. However, consistent results are found in July for the croplands of the Ukraine and southern Russia.

  17. Individual tree growth models for eucalyptus in northern Brazil

    Directory of Open Access Journals (Sweden)

    Fabrina Bolzan Martins

    2014-06-01

    Full Text Available The diameter and height growth model is one of three submodels used for simulating individual tree growth. In Brazil, there are few studies on the dimensional growth of individual trees be they native or exotic species, despite their potential. This study aimed to evaluate diameter and height growth models for individual trees for eucalyptus stands and to validate the best fitting model. Tree diameter and height data were obtained from 48 permanent plots of unthinned stands of Eucalyptus grandis × Eucalyptus urophylla hybrid located in northern Brazil. The evaluation of the diameter and height growth models was based on adjusted coefficient of determination, standard error of estimate as a percentage, trend, root mean square error and Akaike Information Criterion. Analysis also included distribution of residual percentage, statistical significance and signs of the coefficients. The Lundqvist-Korf model provided the most accurate estimates for diameter and height growth, in comparison with the other models, providing better statistical values, greater proximity to observed values and better distribution of residual percentages. The use of this type of model is feasible and can result in significant improvements in the accuracy of yield estimates.

  18. Stability of above-ground and below-ground processes to extreme drought in model grassland ecosystems: Interactions with plant species diversity and soil nitrogen availability.

    OpenAIRE

    Bloor, Juliette; Bardgett, R. D.

    2012-01-01

    Extreme drought events have the potential to cause dramatic changes in ecosystem structure and function, but the controls upon ecosystem stability to drought remain poorly understood. Here we used model systems of two commonly occurring, temperate grassland communities to investigate the shortterm interactive effects of a simulated 100-year summer drought event, soil nitrogen (N) availability and plant species diversity (low/high) on key ecosystem processes related to carbon (C) and N cycling...

  19. Preparing the Dutch delta for future droughts: model based support in the national Delta Programme

    Science.gov (United States)

    ter Maat, Judith; Haasnoot, Marjolijn; van der Vat, Marnix; Hunink, Joachim; Prinsen, Geert; Visser, Martijn

    2014-05-01

    Keywords: uncertainty, policymaking, adaptive policies, fresh water management, droughts, Netherlands, Dutch Deltaprogramme, physically-based complex model, theory-motivated meta-model To prepare the Dutch Delta for future droughts and water scarcity, a nation-wide 4-year project, called Delta Programme, is established to assess impacts of climate scenarios and socio-economic developments and to explore policy options. The results should contribute to a national adaptive plan that is able to adapt to future uncertain conditions, if necessary. For this purpose, we followed a model-based step-wise approach, wherein both physically-based complex models and theory-motivated meta-models were used. First step (2010-2011) was to make a quantitative problem description. This involved a sensitivity analysis of the water system for drought situations under current and future conditions. The comprehensive Dutch national hydrological instrument was used for this purpose and further developed. Secondly (2011-2012) our main focus was on making an inventory of potential actions together with stakeholders. We assessed efficacy, sell-by date of actions, and reassessed vulnerabilities and opportunities for the future water supply system if actions were (not) taken. A rapid assessment meta-model was made based on the complex model. The effects of all potential measures were included in the tool. Thirdly (2012-2013), with support of the rapid assessment model, we assessed the efficacy of policy actions over time for an ensemble of possible futures including sea level rise and climate and land use change. Last step (2013-2014) involves the selection of preferred actions from a set of promising actions that meet the defined objectives. These actions are all modeled and evaluated using the complex model. The outcome of the process will be an adaptive management plan. The adaptive plan describes a set of preferred policy pathways - sequences of policy actions - to achieve targets under

  20. Droughts in the US: Modeling and Forecasting for Agriculture-Water Management and Adaptation

    Science.gov (United States)

    Perveen, S.; Devineni, N.; Lall, U.

    2012-12-01

    More than half of all US counties are currently mired in a drought that is considered the worst in decades. A persistent drought can not only lead to widespread impacts on water access with interstate implications (as has been shown in the Southeast US and Texas), chronic scarcity can emerge as a risk in regions where fossil aquifers have become the primary source of supply and are being depleted at rates much faster than recharge (e.g., Midwestern US). The standardized drought indices on which the drought declarations are made in the US so far consider only the static decision frameworks—where only the supply is the control variable and not the water consumption. If a location has low demands, drought as manifest in the usual indices does not really have "proportionate" social impact. Conversely, a modest drought as indicated by the traditional measures may have significant impacts where demand is close to the climatological mean value of precipitation. This may also lead to drought being declared too late or too soon. Against this fact, the importance of improved drought forecasting and preparedness for different sectors of the economy becomes increasingly important. The central issue we propose to address through this paper is the construction and testing of a drought index that considers regional water demands for specific purposes (e.g., crops, municipal use) and their temporal distribution over the year for continental US. Here, we have highlighted the use of the proposed index for three main sectors: (i) water management organizations, (ii) optimizing agricultural water use, and (iii) supply chain water risk. The drought index will consider day-to-day climate variability and sectoral demands to develop aggregate regional conditions or disaggregated indices for water users. For the daily temperature and precipitation data, we are using NLDAS dataset that is available from 1949 onwards. The national agricultural statistics services (NASS) online database has

  1. A Drought Early Warning System Using System Dynamics Model and Seasonal Climate Forecasts: a case study in Hsinchu, Taiwan.

    Science.gov (United States)

    Tien, Yu-Chuan; Tung, Ching-Ping; Liu, Tzu-Ming; Lin, Chia-Yu

    2016-04-01

    In the last twenty years, Hsinchu, a county of Taiwan, has experienced a tremendous growth in water demand due to the development of Hsinchu Science Park. In order to fulfill the water demand, the government has built the new reservoir, Baoshan second reservoir. However, short term droughts still happen. One of the reasons is that the water level of the reservoirs in Hsinchu cannot be reasonably forecasted, which sometimes even underestimates the severity of drought. The purpose of this study is to build a drought early warning system that projects the water levels of two important reservoirs, Baoshan and Baoshan second reservoir, and also the spatial distribution of water shortagewith the lead time of three months. Furthermore, this study also attempts to assist the government to improve water resources management. Hence, a system dynamics model of Touchien River, which is the most important river for public water supply in Hsinchu, is developed. The model consists of several important subsystems, including two reservoirs, water treatment plants and agricultural irrigation districts. Using the upstream flow generated by seasonal weather forecasting data, the model is able to simulate the storage of the two reservoirs and the distribution of water shortage. Moreover, the model can also provide the information under certain emergency scenarios, such as the accident or failure of a water treatment plant. At last, the performance of the proposed method and the original water resource management method that the government used were also compared. Keyword: Water Resource Management, Hydrology, Seasonal Climate Forecast, Reservoir, Early Warning, Drought

  2. Mexican drought: an observational modeling and tree ring study of variability and climate change

    Energy Technology Data Exchange (ETDEWEB)

    Seager, R.; Ting, M. [Lamont-Doherty Earth Observatory of Columbia University, Palisades, NY (United States)]. E-mail: seager@ldeo.columbia.edu; Davis, M. [Department of History, University of California at Irvine, CA (United States); Cane, M.; Naik, N.; Nakamura, J.; Li, C.; Cook, E. [Lamont-Doherty Earth Observatory of Columbia University, Palisades, NY (United States); Stahle, D.W. [Tree Ring Laboratory, University of Arkansas, Fayetteville, Arkansas (United States)

    2009-01-15

    Variability of Mexican hydroclimate, with special attention to persistent drought, is examined using observations, model simulations forced by historical sea surface temperature (SST), tree ring reconstructions of past climate and model simulations and projections of naturally and anthropogenically forced climate change. During the winter half year, hydroclimate across Mexico is influenced by the state of the tropical Pacific Ocean with the Atlantic playing little role. Mexican winters tend to be wetter during El Nino conditions. In the summer half year northern Mexico is also wetter when El Nino conditions prevail, but southern Mexico is drier. A warm tropical North Atlantic Ocean makes northern Mexico dry and southern Mexico wet. These relationships are reasonably well reproduced in ensembles of atmosphere model simulations forced by historical SST for the period from 1856 to 2002. Large ensembles of 100 day long integrations are used to examine the day to day evolution of the atmospheric circulation and precipitation in response to a sudden imposition of a El Nino SST anomaly in the summer half year. Kelvin waves propagate east and immediately cause increased column-integrated moisture divergence and reduced precipitation over the tropical Americas and Intra-America Seas. Within a few days a low level high pressure anomaly develops over the Gulf of Mexico. A forced nonlinear model is used to demonstrate that this low is forced by the reduced atmospheric heating over the tropical Atlantic-Intra-America Seas area. Tree ring reconstructions that extend back before the period of instrumental precipitation data coverage are used to verify long model simulations forced by historical SST. The early to mid 1950s drought in northern Mexico appears to have been the most severe since the mid nineteenth century and likely arose as a response to both a multiyear La Nina and a warm tropical North Atlantic. A drought in the 1890s was also severe and appears driven by a

  3. Drought impact functions as intermediate step towards drought damage assessment

    Science.gov (United States)

    Bachmair, Sophie; Svensson, Cecilia; Prosdocimi, Ilaria; Hannaford, Jamie; Helm Smith, Kelly; Svoboda, Mark; Stahl, Kerstin

    2016-04-01

    While damage or vulnerability functions for floods and seismic hazards have gained considerable attention, there is comparably little knowledge on drought damage or loss. On the one hand this is due to the complexity of the drought hazard affecting different domains of the hydrological cycle and different sectors of human activity. Hence, a single hazard indicator is likely not able to fully capture this multifaceted hazard. On the other hand, drought impacts are often non-structural and hard to quantify or monetize. Examples are impaired navigability of streams, restrictions on domestic water use, reduced hydropower production, reduced tree growth, and irreversible deterioration/loss of wetlands. Apart from reduced crop yield, data about drought damage or loss with adequate spatial and temporal resolution is scarce, making the development of drought damage functions difficult. As an intermediate step towards drought damage functions we exploit text-based reports on drought impacts from the European Drought Impact report Inventory and the US Drought Impact Reporter to derive surrogate information for drought damage or loss. First, text-based information on drought impacts is converted into timeseries of absence versus presence of impacts, or number of impact occurrences. Second, meaningful hydro-meteorological indicators characterizing drought intensity are identified. Third, different statistical models are tested as link functions relating drought hazard indicators with drought impacts: 1) logistic regression for drought impacts coded as binary response variable; and 2) mixture/hurdle models (zero-inflated/zero-altered negative binomial regression) and an ensemble regression tree approach for modeling the number of drought impact occurrences. Testing the predictability of (number of) drought impact occurrences based on cross-validation revealed a good agreement between observed and modeled (number of) impacts for regions at the scale of federal states or

  4. The German drought monitor

    Science.gov (United States)

    Zink, Matthias; Samaniego, Luis; Kumar, Rohini; Thober, Stephan; Mai, Juliane; Schäfer, David; Marx, Andreas

    2016-07-01

    The 2003 drought event in Europe had major implications on many societal sectors, including energy production, health, forestry and agriculture. The reduced availability of water accompanied by high temperatures led to substantial economic losses on the order of 1.5 Billion Euros, in agriculture alone. Furthermore, soil droughts have considerable impacts on ecosystems, forest fires and water management. Monitoring soil water availability in near real-time and at high-resolution, i.e., 4 × 4 km2, enables water managers to mitigate the impact of these extreme events. The German drought monitor was established in 2014 as an online platform. It uses an operational modeling system that consists of four steps: (1) a daily update of observed meteorological data by the German Weather Service, with consistency checks and interpolation; (2) an estimation of current soil moisture using the mesoscale hydrological model; (3) calculation of a quantile-based soil moisture index (SMI) based on a 60 year data record; and (4) classification of the SMI into five drought classes ranging from abnormally dry to exceptional drought. Finally, an easy to understand map is produced and published on a daily basis on www.ufz.de/droughtmonitor. Analysis of the ongoing 2015 drought event, which garnered broad media attention, shows that 75% of the German territory underwent drought conditions in July 2015. Regions such as Northern Bavaria and Eastern Saxony, however, have been particularly prone to drought conditions since autumn 2014. Comparisons with historical droughts show that the 2015 event is amongst the ten most severe drought events observed in Germany since 1954 in terms of its spatial extent, magnitude and duration.

  5. Accelerated Growth Rate and Increased Drought Stress Resilience of the Model Grass Brachypodium distachyon Colonized by Bacillus subtilis B26.

    Science.gov (United States)

    Gagné-Bourque, François; Mayer, Boris F; Charron, Jean-Benoit; Vali, Hojatollah; Bertrand, Annick; Jabaji, Suha

    2015-01-01

    Plant growth-promoting bacteria (PGB) induce positive effects in plants, for instance, increased growth and reduced abiotic stresses susceptibility. The mechanisms by which these bacteria impact the host plant are numerous, diverse and often specific. Here, we studied the agronomical, molecular and biochemical effects of the endophytic PGB Bacillus subtilis B26 on the full life cycle of Brachypodium distachyon Bd21, an established model species for functional genomics in cereal crops and temperate grasses. Inoculation of Brachypodium with B. subtilis strain B26 increased root and shoot weights, accelerated growth rate and seed yield as compared to control plants. B. subtilis strain B26 efficiently colonized the plant and was recovered from roots, stems and blades as well as seeds of Brachypodium, indicating that the bacterium is able to migrate, spread systemically inside the plant, establish itself in the aerial plant tissues and organs, and is vertically transmitted to seeds. The presence of B. subtilis strain B26 in the seed led to systemic colonization of the next generation of Brachypodium plants. Inoculated Brachypodium seedlings and mature plants exposed to acute and chronic drought stress minimized the phenotypic effect of drought compared to plants not harbouring the bacterium. Protection from the inhibitory effects of drought by the bacterium was linked to upregulation of the drought-response genes, DREB2B-like, DHN3-like and LEA-14-A-like and modulation of the DNA methylation genes, MET1B-like, CMT3-like and DRM2-like, that regulate the process. Additionally, total soluble sugars and starch contents increased in stressed inoculated plants, a biochemical indication of drought tolerance. In conclusion, we show a single inoculation of Brachypodium with a PGB affected the whole growth cycle of the plant, accelerating its growth rates, shortening its vegetative period, and alleviating drought stress effects. These effects are relevant to grasses and cereal

  6. Accelerated Growth Rate and Increased Drought Stress Resilience of the Model Grass Brachypodium distachyon Colonized by Bacillus subtilis B26.

    Directory of Open Access Journals (Sweden)

    François Gagné-Bourque

    Full Text Available Plant growth-promoting bacteria (PGB induce positive effects in plants, for instance, increased growth and reduced abiotic stresses susceptibility. The mechanisms by which these bacteria impact the host plant are numerous, diverse and often specific. Here, we studied the agronomical, molecular and biochemical effects of the endophytic PGB Bacillus subtilis B26 on the full life cycle of Brachypodium distachyon Bd21, an established model species for functional genomics in cereal crops and temperate grasses. Inoculation of Brachypodium with B. subtilis strain B26 increased root and shoot weights, accelerated growth rate and seed yield as compared to control plants. B. subtilis strain B26 efficiently colonized the plant and was recovered from roots, stems and blades as well as seeds of Brachypodium, indicating that the bacterium is able to migrate, spread systemically inside the plant, establish itself in the aerial plant tissues and organs, and is vertically transmitted to seeds. The presence of B. subtilis strain B26 in the seed led to systemic colonization of the next generation of Brachypodium plants. Inoculated Brachypodium seedlings and mature plants exposed to acute and chronic drought stress minimized the phenotypic effect of drought compared to plants not harbouring the bacterium. Protection from the inhibitory effects of drought by the bacterium was linked to upregulation of the drought-response genes, DREB2B-like, DHN3-like and LEA-14-A-like and modulation of the DNA methylation genes, MET1B-like, CMT3-like and DRM2-like, that regulate the process. Additionally, total soluble sugars and starch contents increased in stressed inoculated plants, a biochemical indication of drought tolerance. In conclusion, we show a single inoculation of Brachypodium with a PGB affected the whole growth cycle of the plant, accelerating its growth rates, shortening its vegetative period, and alleviating drought stress effects. These effects are relevant to

  7. Development of an agricultural drought assessment system : integration of agrohydrological modelling, remote sensing and geographical information

    NARCIS (Netherlands)

    Vazifedoust, M.

    2007-01-01

    Iran faces widespread droughts regularly, causing large economical and social damages. The agricultural sector is with 80-90 % by far the largest user of water in Iran and is often the first sector to be affected by drought. Unfortunately, water management in agriculture is also rather poor and henc

  8. On the utility of land surface models for agricultural drought monitoring

    Directory of Open Access Journals (Sweden)

    W. T. Crow

    2012-09-01

    Full Text Available The lagged rank cross-correlation between model-derived root-zone soil moisture estimates and remotely sensed vegetation indices (VI is examined between January 2000 and December 2010 to quantify the skill of various soil moisture models for agricultural drought monitoring. Examined modeling strategies range from a simple antecedent precipitation index to the application of modern land surface models (LSMs based on complex water and energy balance formulations. A quasi-global evaluation of lagged VI/soil moisture cross-correlation suggests, when globally averaged across the entire annual cycle, soil moisture estimates obtained from complex LSMs provide little added skill (< 5% in relative terms in anticipating variations in vegetation condition relative to a simplified water accounting procedure based solely on observed precipitation. However, larger amounts of added skill (5–15% in relative terms can be identified when focusing exclusively on the extra-tropical growing season and/or utilizing soil moisture values acquired by averaging across a multi-model ensemble.

  9. How Do Biases in General Circulation Models Affect Projections of Aridity and Drought?

    Science.gov (United States)

    Ficklin, D. L.; Abatzoglou, J. T.; Robeson, S. M.; Dufficy, A. L.

    2015-12-01

    Unless corrected, biases in General Circulation Models (GCMs) can affect hydroclimatological applications and projections. Compared to a raw GCM ensemble (direct GCM output), bias-corrected GCM inputs correct for systematic errors and can produce high-resolution projections that are useful for impact analyses. By examining the difference between raw and bias-corrected GCMs for the continental United States, this work highlights how GCM biases can affect projections of aridity (defined as precipitation (P)/potential evapotranspiration (PET)) and drought (using the Palmer Drought Severity Index (PDSI)). At the annual time scale for spatial averages over the continental United States, the raw GCM ensemble median has a historical positive precipitation bias (+24%) and negative PET bias (-7%) compared to the bias-corrected output. While both GCM ensembles (raw and bias-corrected) result in drier conditions in the future, the bias-corrected GCMs produce enhanced aridity (number of months with PET>P) in the late 21st century (2070-2099) compared to the historical climate (1950-1979). For the western United States, the bias-corrected GCM ensemble estimates much less humid and sub-humid conditions (based on P/PET categorical values) than the raw GCM ensemble. However, using June, July, and August PDSI, the bias-corrected GCM ensemble projects less acute decreases for the southwest United States compared to the raw GCM ensemble (1 to 2 PDSI units higher) as a result of larger decreases in projected precipitation in the raw GCM ensemble. A number of examples and ecological implications of this work for the western United States will be presented.

  10. Estimating drought risk across Europe from reported drought impacts, drought indices, and vulnerability factors

    Science.gov (United States)

    Blauhut, Veit; Stahl, Kerstin; Stagge, James Howard; Tallaksen, Lena M.; De Stefano, Lucia; Vogt, Jürgen

    2016-07-01

    Drought is one of the most costly natural hazards in Europe. Due to its complexity, drought risk, meant as the combination of the natural hazard and societal vulnerability, is difficult to define and challenging to detect and predict, as the impacts of drought are very diverse, covering the breadth of socioeconomic and environmental systems. Pan-European maps of drought risk could inform the elaboration of guidelines and policies to address its documented severity and impact across borders. This work tests the capability of commonly applied drought indices and vulnerability factors to predict annual drought impact occurrence for different sectors and macro regions in Europe and combines information on past drought impacts, drought indices, and vulnerability factors into estimates of drought risk at the pan-European scale. This hybrid approach bridges the gap between traditional vulnerability assessment and probabilistic impact prediction in a statistical modelling framework. Multivariable logistic regression was applied to predict the likelihood of impact occurrence on an annual basis for particular impact categories and European macro regions. The results indicate sector- and macro-region-specific sensitivities of drought indices, with the Standardized Precipitation Evapotranspiration Index (SPEI) for a 12-month accumulation period as the overall best hazard predictor. Vulnerability factors have only limited ability to predict drought impacts as single predictors, with information about land use and water resources being the best vulnerability-based predictors. The application of the hybrid approach revealed strong regional and sector-specific differences in drought risk across Europe. The majority of the best predictor combinations rely on a combination of SPEI for shorter and longer accumulation periods, and a combination of information on land use and water resources. The added value of integrating regional vulnerability information with drought risk prediction

  11. Evidence-based modelling of diverse plant water use strategies on stomatal and non-stomatal components under drought

    Science.gov (United States)

    zhou, S.; Prentice, C.; Medlyn, B. E.; Sabaté, S.

    2013-12-01

    Models disagree on how to represent effects of drought stress on plant gas exchange. Some models assume drought stress affects the marginal water use efficiency of plants (marginal WUE; i.e. the change in photosynthesis per unit of change in transpiration) whereas others assume drought stress acts directly on photosynthetic capacity. It is not clear whether either of these approaches is sufficient to capture the drought response, or whether the effect of drought varies among species and functional types. A collection of Eucalyptus and Quercus species derived from different hydro-climate habitats, in together with two European riparian species, were conducted with drought treatments respectively in Australia and Spain for three months. Measurements included net CO2 assimilation rate versus substomatal CO2 concentration (A-Ci) curves, fluorescence, and predawn leaf water potential at increasing levels of water stress. The correlations with quantitative plant traits of leaf, stomata, vessel, and wood density, leaf nitrogen content and 13C discrimination were also explored. We analysed the effect of drought effect on leaf gas exchange with a recently developed stomatal model that reconciles the empirical and optimal approaches on predicting optimal stomatal conductance. The model's single parameter g1 is a decreasing function of marginal WUE. The two genera showed consistence on the contrasting response patterns between species derived from mesic and arid habitats, which differed greatly in their estimated g1 values under moist conditions, and in the rate at which g1 declined with water stress. They also differed greatly in the predawn water potential at which apparent carboxylation capacity (apparent Vcmax) and mesophyll conductance (gm) declined most steeply, and in the steepness of this decline. Principal components analysis revealed a gradient in water relation strategies from sclerophyll species to malacophyll species. Malacophylls had higher g1, apparent Vcmax

  12. Stochastic prediction of drought class transitions

    OpenAIRE

    Paulo, Ana A.; L. S. Pereira

    2008-01-01

    This paper aims at the stochastic characterization of droughts applying Markov chains modeling to drought class transitions derived from SPI time series. Several sites in Southern Portugal having updated data on precipitation available were considered. The drought class probabilities, the expected residence time in each class of severity, the expected time for the transition between drought classes and the drought severity class predictions 1, 2, or 3 months ahead have been obt...

  13. Bivariate drought analysis using entropy theory

    OpenAIRE

    Hao, Zengchao; Singh, Vijay P

    2012-01-01

    Drought analysis is important for water resources planning and management. Drought duration and severity are two main characteristics that have often been used for drought analysis, which can be defined using run theory with hydrological variables (e. g., streamflow). A traditional way to characterize the drought duration or severity is based on fitting a probability density function. The drought duration can be modeled by a geometric distribution (discrete) or an exponential distribution ...

  14. Irrigated Agriculture in Morocco: An Agent-Based Model of Adaptation and Decision Making Amid Increasingly Frequent Drought Events

    Science.gov (United States)

    Norton, M.

    2015-12-01

    In the past 100 years, Morocco has undertaken a heavy investment in developing water infrastructure that has led to a dramatic expansion of irrigated agriculture. Irrigated agriculture is the primary user of water in many arid countries, often accounting for 80-90% of total water usage. Irrigation is adopted by farmers not only because it leads to increased production, but also because it improves resilience to an uncertain climate. However, the Mediterranean region as a whole has also seen an increase in the frequency and severity of drought events. These droughts have had a dramatic impact on farmer livelihoods and have led to a number of coping strategies, including the adoption or disadoption of irrigation. In this study, we use a record of the annual extent of irrigated agriculture in Morocco to model the effect of drought on the extent of irrigated agriculture. Using an agent-based socioeconomic model, we seek to answer the following questions: 1) Do farmers expand irrigated agriculture in response to droughts? 2) Do drought events entail the removal of perennial crops like orchards? 3) Can we detect the retreat of irrigated agriculture in the more fragile watersheds of Morocco? Understanding the determinants of irrigated crop expansion and contractions will help us understand how agro-ecological systems transition from 20th century paradigms of expansion of water supply to a 21st century paradigm of water use efficiency. The answers will become important as countries learn how to manage water in new climate regimes characterized by less reliable and available precipitation.

  15. Proposed Hydrodynamic Model Improves Resolution of Species-Specific Responses to Drought and Disturbance

    Science.gov (United States)

    Matheny, A. M.; Bohrer, G.; Fiorella, R.; Mirfenderesgi, G.

    2015-12-01

    Plant functional types in land surface models (LSMs) are broadly defined, and often represent species with different physiologies within the same category. For example, trees of opposing hydraulic strategies and traits are commonly grouped together, as is the case of red oak and red maple. As a result, LSMs generate typical patterns of errors in predictions of transpiration and production. We studied sap flux, stem water storage, stomatal conductance, photosynthesis, rooting depth, and bole growth of these species at disturbed and undisturbed field sites in Michigan. Species-specific differences significantly impact temporal patterns of stomatal conductance and overall transpiration responses to both drought and disturbance. During drought, maples relied heavily on stem-stored water, while oaks did not. After disturbance, oaks increased stomatal conductance while maple conductance declined. Isotopic analysis of xylem water revealed that oak roots can access a deep groundwater source, which maple roots cannot. This deep rooting strategy permits transpiration and growth to continue in oaks during periods of water limitation, even when maples cease transpiration. Using 16 years of bole growth data, we show that maple growth is strongly correlated with mean annual precipitation, yet oak growth is not. We propose a framework to incorporate these species-specific differences into LSMs using the Finite-Element Tree-Crown Hydrodynamics model version 2 (FETCH2) that resolves the fast dynamics and diurnal hysteresis of stomatal conductance at the tree level. FETCH2 uses atmospheric and biological forcings from the LSM, simulates water movement through trees as flow through a system of porous media conduits, and calculates realistic hydraulic restrictions to stomatal conductance. This model replaces the current, non-physical link which empirically connects soil moisture to stomatal conductance in LSMs. FETCH2 resolved transpiration is then easily scaled to the plot level

  16. A study of 2014 record drought in India with CFSv2 model: role of water vapor transport

    Science.gov (United States)

    Ramakrishna, S. S. V. S.; Brahmananda Rao, V.; Srinivasa Rao, B. R.; Hari Prasad, D.; Nanaji Rao, N.; Panda, Roshmitha

    2016-09-01

    The Indian summer monsoon season of 2014 was erratic and ended up with a seasonal rainfall deficit of 12 % and a record drought in June. In this study we analyze the moisture transport characteristics for the monsoon season of 2014 using both NCEP FNL reanalysis (FNL) and CFSv2 (CFS) model data. In FNL, in June 2014 there was a large area of divergence of moisture flux. In other months also there was lesser flux. This probably is the cause of 2014 drought. The CFS model overestimated the drought and it reproduces poorly the observed rainfall over central India (65E-95E; 5N-35N). The correlation coefficient (CC) between the IMD observed rainfall and CFS model rainfall is only 0.1 while the CC between rainfall and moisture flux convergence in CFS model is only 0.20 and with FNL data -0.78. This clearly shows that the CFS model has serious difficulty in reproducing the moisture flux convergence and rainfall. We found that the rainfall variations are strongly related to the moisture convergence or divergence. The hypothesis of Krishnamurti et al. (J Atmos Sci 67:3423-3441, 2010) namely the intrusion of west African desert air and the associated low convective available potential energy inhibiting convection and rainfall shows some promise to explain dry spells in Indian summer monsoon. However, the rainfall or lack of it is mainly explained by convergence or divergence of moisture flux.

  17. A water-table dependent reservoir model to investigate the effect of drought and vascular plant invasion on peatland hydrology

    Science.gov (United States)

    Binet, Stéphane; Gogo, Sébastien; Laggoun-Défarge, Fatima

    2013-08-01

    This paper investigates the peat saturation and the air entrapment dynamics in a peatland, estimated from the water table fluctuations. A reservoirs model of water table fluctuations in a double-porosity peat is proposed, by calculating the stored water in effective porosity of the peat from precipitation and evapotranspiration datasets. Calculations conceptualize vascular plant consumption through a crop coefficient. Changes in water storage, located in the effective porosity of the peat, are described through a maximum infiltration rate and a maximum storage capacity. Water discharges take place in runoff and percolation reservoirs. The runoff coefficient is considered to be water table dependent. This model was tested on a peatland that has experienced strong water table fluctuations caused by summer drought and/or by vascular plant water consumption. A water table dependent runoff model appeared to be adequate to describe the water table fluctuations in peatland. From this model, vascular plants were found to increase the crop coefficient and to limit percolation through the peat. The high water table depth in winter was found to change with the years and is related to an equilibrium between slow infiltration in peat versus percolation plus evapotranspiration. In this disturbed peatland, even if overland flows occurred after a drought, the re-saturation of effective porosity was slow with about 30% of air trapped in the porosity 6 months after the drought period. The effects of a drought on peat saturation were observed over more than a single hydrological cycle. This can affect the biogeochemical processes controlling the C cycle in peatland.

  18. Hydrosedimentological modeling of watershed in southeast Brazil, using SWAT

    Directory of Open Access Journals (Sweden)

    Maria Lúcia Calijuri

    2010-08-01

    Full Text Available The quantitative evaluation of soil loss due to erosion, of water loss and of load sediments that reach water bodies is fundamental to the environmental planning of a watershed, contributing to the process of decision for best options for soil tillage and water quality maintenance. Estimates of these data have been accomplished throughout the world using empiric or conceptual models. Besides being economically viable in scenarios development, environmental models may contribute to the location of critical areas, leading to emergency contention operations caused by erosive processes. Among these models, we highlight the SWAT (Soil and Water Assessment Tool which was applied in São Bartolomeu watershed, located in the Zona da Mata, Minas Gerais state, southeastern Brazil, to identify areas of greater sensitivity to erosion considering the soil type and land use. To validate the model, 10 experimental plots were installed in the dominant crops of the watershed between 2006 and 2008, for monitoring the runoff and soil losses under natural rainfall. Field results and simulations showed the SWAT efficiency for sediment yield and soil losses estimations, as they are influenced by factors such as soil moisture, rainfall intensity, soil type and land use (dominated by Oxisols, Ultisols, Inceptisols and Entisols. These losses can be reduced significantly by improving crops management of. A simulation scenario replacing pastures cover by Eucalyptus was introduced, which significantly reduced soil loss in many parts of the watershed.

  19. Towards developing drought impact functions to advance drought monitoring and early warning

    Science.gov (United States)

    Bachmair, Sophie; Stahl, Kerstin; Hannaford, Jamie; Svoboda, Mark

    2015-04-01

    , damage, or loss due to drought, and (3) to test different statistical models to link drought intensity with drought impact information to derive meaningful thresholds. While the focus regarding drought impact variables lies on text-based impact reports from the European Drought Impact report Inventory (EDII) and the US Drought Impact Reporter (DIR), the information gain through exploiting other variables such as agricultural yield statistics and remotely sensed vegetation indices is explored. First results reveal interesting insights into the complex relationship between drought indicators and impacts and highlight differences among drought impact variables and geographies. Although a simple intensity threshold evoking specific drought impacts cannot be identified, developing drought impact functions helps to elucidate how drought conditions relate to ecological or socioeconomic impacts. Such knowledge may provide guidance for inferring meaningful triggers for drought M&EW and could have potential for a wide range of drought management applications (for example, building drought scenarios for testing the resilience of drought plans or water supply systems).

  20. Springtime soil moisture, natural climatic variability, and North American drought as simulated by the NCAR Community Climate Model 1

    Science.gov (United States)

    Oglesby, Robert J.

    1991-01-01

    Previous results concerning the role that summertime soil moisture reductions can play in amplifying or maintaining North American droughts are extended to include the role of springtime soil moisture reductions and the role that natural climatic variability, as expressed in soil moisture, can play. General circulation model (GCM) simulations with the NCAR Community Climate Model have been made with initial desert-like soil moisture anomalies imposed on 1 May and on 1 March. The May simulation maintained the imposed anomaly throughout the summer, while in the March simulation the anomaly was ameliorated within one month. Thus, the timing of soil moisture reductions may be crucial. A 10-year model control integration with prescribed sea surface temperatures yielded 1 year with late spring and summer soil moisture values similar to those of the 1 May anomaly simulation. This suggests that occasional widespread North American droughts may be an inherent feature of at least the GCM employed for this study. The results also demonstrate the important role played by moisture transport from the Gulf of Mexico in modulating or ameliorating drought conditions for much of the south-central United States, a topic that requires considerable further investigation.

  1. Land degradation, drought and food security in a less-favoured area in the Ethiopian highlands: a bio-economic model with market imperfections

    OpenAIRE

    Holden, Stein; Shiferaw, Bekele

    2004-01-01

    This paper presents a bio-economic model of Andit Tid, a severely degraded crop-livestock farming system with high population density and good market access in the highlands of Ethiopia. Land degradation, population growth, stagnant technology, and drought threaten food security in the area. Drought or weather risk appears to have increased in recent years. The bio-economic model is used to analyse the combined effects of land degradation, population growth, market imperfections and increased...

  2. Disentangling the uncertainty of hydrologic drought characteristics in a multi-model century-long experiment in continental river basins

    Science.gov (United States)

    Samaniego, Luis; Kumar, Rohini; Pechlivanidis, Illias; Breuer, Lutz; Wortmann, Michel; Vetter, Tobias; Flörke, Martina; Chamorro, Alejandro; Schäfer, David; Shah, Harsh; Zeng, Xiaofan

    2016-04-01

    The quantification of the predictive uncertainty in hydrologic models and their attribution to its main sources is of particular interest in climate change studies. In recent years, a number of studies have been aimed at assessing the ability of hydrologic models (HMs) to reproduce extreme hydrologic events. Disentangling the overall uncertainty of streamflow -including its derived low-flow characteristics- into individual contributions, stemming from forcings and model structure, has also been studied. Based on recent literature, it can be stated that there is a controversy with respect to which source is the largest (e.g., Teng, et al. 2012, Bosshard et al. 2013, Prudhomme et al. 2014). Very little has also been done to estimate the relative impact of the parametric uncertainty of the HMs with respect to overall uncertainty of low-flow characteristics. The ISI-MIP2 project provides a unique opportunity to understand the propagation of forcing and model structure uncertainties into century-long time series of drought characteristics. This project defines a consistent framework to deal with compatible initial conditions for the HMs and a set of standardized historical and future forcings. Moreover, the ensemble of hydrologic model predictions varies across a broad range of climate scenarios and regions. To achieve this goal, we use six preconditioned hydrologic models (HYPE or HBV, mHM, SWIM, VIC, and WaterGAP3) set up in seven large continental river basins: Amazon, Blue Nile, Ganges, Niger, Mississippi, Rhine, Yellow. These models are forced with bias-corrected outputs of five CMIP5 general circulation models (GCM) under four extreme representative concentration pathway (RCP) scenarios (i.e. 2.6, 4.5, 6.0, and 8.5 Wm-2) for the period 1971-2099. Simulated streamflow is transformed into a monthly runoff index (RI) to analyze the attribution of the GCM and HM uncertainty into drought magnitude and duration over time. Uncertainty contributions are investigated

  3. Safety performance models for urban intersections in Brazil.

    Science.gov (United States)

    Barbosa, Heloisa; Cunto, Flávio; Bezerra, Bárbara; Nodari, Christine; Jacques, Maria Alice

    2014-09-01

    This paper presents a modeling effort for developing safety performance models (SPM) for urban intersections for three major Brazilian cities. The proposed methodology for calibrating SPM has been divided into the following steps: defining the safety study objective, choosing predictive variables and sample size, data acquisition, defining model expression and model parameters and model evaluation. Among the predictive variables explored in the calibration phase were exposure variables (AADT), number of lanes, number of approaches and central median status. SPMs were obtained for three cities: Fortaleza, Belo Horizonte and Brasília. The SPM developed for signalized intersections in Fortaleza and Belo Horizonte had the same structure and the most significant independent variables, which were AADT entering the intersection and number of lanes, and in addition, the coefficient of the best models were in the same range of values. For Brasília, because of the sample size, the signalized and unsignalized intersections were grouped, and the AADT was split in minor and major approaches, which were the most significant variables. This paper also evaluated SPM transferability to other jurisdiction. The SPM for signalized intersections from Fortaleza and Belo Horizonte have been recalibrated (in terms of the Cx) to the city of Porto Alegre. The models were adjusted following the Highway Safety Manual (HSM) calibration procedure and yielded Cx of 0.65 and 2.06 for Fortaleza and Belo Horizonte SPM respectively. This paper showed the experience and future challenges toward the initiatives on development of SPMs in Brazil, that can serve as a guide for other countries that are in the same stage in this subject.

  4. Receptor models for source apportionment of remote aerosols in Brazil

    International Nuclear Information System (INIS)

    The PIXE (particle induced X-ray emission), and PESA (proton elastic scattering analysis) method were used in conjunction with receptor models for source apportionment of remote aerosols in Brazil. The PIXE used in the determination of concentration for elements with Z >- 11, has a detection limit of about 1 ng/m3. The concentrations of carbon, nitrogen and oxygen in the fine fraction of Amazon Basin aerosols was measured by PESA. We sampled in Jureia (SP), Fernando de Noronha, Arembepe (BA), Firminopolis (GO), Itaberai (GO) and Amazon Basin. For collecting the airbone particles we used cascade impactors, stacked filter units, and streaker samplers. Three receptor models were used: chemical mass balance, stepwise multiple regression analysis and principal factor analysis. The elemental and gravimetric concentrations were explained by the models within the experimental errors. Three sources of aerosol were quantitatively distinguished: marine aerosol, soil dust and aerosols related to forests. The emission of aerosols by vegetation is very clear for all the sampling sites. In Amazon Basin and Jureia it is the major source, responsible for 60 to 80% of airborne concentrations. (Author)

  5. Elusive drought: uncertainty in observed trends and short- and long-term CMIP5 projections

    Science.gov (United States)

    Orlowsky, B.; Seneviratne, S. I.

    2013-05-01

    Recent years have seen a number of severe droughts in different regions around the world, causing agricultural and economic losses, famines and migration. Despite their devastating consequences, the Standardised Precipitation Index (SPI) of these events lies within the general range of observation-based SPI time series and simulations from the 5th phase of the Coupled Model Intercomparison Project (CMIP5). In terms of magnitude, regional trends of SPI over the last decades remain mostly inconclusive in observation-based datasets and CMIP5 simulations, but Soil Moisture Anomalies (SMAs) in CMIP5 simulations hint at increased drought in a few regions (e.g., the Mediterranean, Central America/Mexico, the Amazon, North-East Brazil and South Africa). Also for the future, projections of changes in the magnitude of meteorological (SPI) and soil moisture (SMA) drought in CMIP5 display large spreads over all time frames, generally impeding trend detection. However, projections of changes in the frequencies of future drought events display more robust signal-to-noise ratios, with detectable trends towards more frequent drought before the end of the 21st century in the Mediterranean, South Africa and Central America/Mexico. Other present-day hot spots are projected to become less drought-prone, or display non-significant changes in drought occurrence. A separation of different sources of uncertainty in projections of meteorological and soil moisture drought reveals that for the near term, internal climate variability is the dominant source, while the formulation of Global Climate Models (GCMs) generally becomes the dominant source of spread by the end of the 21st century, especially for soil moisture drought. In comparison, the uncertainty from Green-House Gas (GHG) concentrations scenarios is negligible for most regions. These findings stand in contrast to respective analyses for a heat wave index, for which GHG concentrations scenarios constitute the main source of

  6. Elusive drought: uncertainty in observed trends and short- and long-term CMIP5 projections

    Directory of Open Access Journals (Sweden)

    B. Orlowsky

    2012-12-01

    Full Text Available Recent years have seen a number of severe droughts in different regions around the world, causing agricultural and economic losses, famines and migration. Despite their devastating consequences, the Standardised Precipitation Index (SPI of these events lies within the range of internal climate variability, which we estimate from simulations from the 5th phase of the Coupled Model Intercomparison Project (CMIP5. In terms of drought magnitude, regional trends of SPI over the last decades remain mostly inconclusive in observations and CMIP5 simulations, although Soil Moisture Anomalies (SMAs in CMIP5 simulations hint at increased drought in a few regions (e.g. the Mediterranean, Central America/Mexico, the Amazon, North-East Brazil and South Africa. Also for the future, projections of meteorological (SPI and agricultural (SMA drought in CMIP5 display large uncertainties over all time frames, generally impeding trend detection. Analogue analyses of the frequencies rather than magnitudes of future drought display, however, more robust signal-to-noise ratios with detectable trends towards more frequent drought until the end of the 21st century in the Mediterranean, South Africa and Central America/Mexico. Other present-day hot spots are projected to become less drought-prone, or to display unsignificant changes in drought occurrence. A separation of different sources of uncertainty in drought projections reveals that for the near term, internal climate variability is the dominant source, while the formulation of Global Climate Models (GCMs generally becomes the dominant source of uncertainty by the end of the 21st century, especially for agricultural (soil moisture drought. In comparison, the uncertainty in Green-House Gas (GHG concentrations scenarios is negligible for most regions. These findings stand in contrast to respective analyses for a heat wave indicator, for which GHG concentrations scenarios constitute the main source of uncertainty. Our

  7. DROUGHT FORECASTING BASED ON MACHINE LEARNING OF REMOTE SENSING AND LONG-RANGE FORECAST DATA

    OpenAIRE

    Rhee, J; J. Im; Park, S

    2016-01-01

    The reduction of drought impacts may be achieved through sustainable drought management and proactive measures against drought disaster. Accurate and timely provision of drought information is essential. In this study, drought forecasting models to provide high-resolution drought information based on drought indicators for ungauged areas were developed. The developed models predict drought indices of the 6-month Standardized Precipitation Index (SPI6) and the 6-month Standardized Precipitatio...

  8. Probabilistic Forecasting of Drought Events Using Markov Chain- and Bayesian Network-Based Models: A Case Study of an Andean Regulated River Basin

    Directory of Open Access Journals (Sweden)

    Alex Avilés

    2016-01-01

    Full Text Available The scarcity of water resources in mountain areas can distort normal water application patterns with among other effects, a negative impact on water supply and river ecosystems. Knowing the probability of droughts might help to optimize a priori the planning and management of the water resources in general and of the Andean watersheds in particular. This study compares Markov chain- (MC and Bayesian network- (BN based models in drought forecasting using a recently developed drought index with respect to their capability to characterize different drought severity states. The copula functions were used to solve the BNs and the ranked probability skill score (RPSS to evaluate the performance of the models. Monthly rainfall and streamflow data of the Chulco River basin, located in Southern Ecuador, were used to assess the performance of both approaches. Global evaluation results revealed that the MC-based models predict better wet and dry periods, and BN-based models generate slightly more accurately forecasts of the most severe droughts. However, evaluation of monthly results reveals that, for each month of the hydrological year, either the MC- or BN-based model provides better forecasts. The presented approach could be of assistance to water managers to ensure that timely decision-making on drought response is undertaken.

  9. Diagnosis of North American Multi-Model Ensemble (NMME) skill for predicting floods and droughts over the continental USA

    Science.gov (United States)

    Slater, L. J.; Villarini, G.; Bradley, A.

    2015-12-01

    Model predictions of precipitation and temperature are crucial to mitigate the impacts of major flood and drought events through informed planning and response. However, the potential value and applicability of these predictions is inescapably linked to their forecast quality. The North-American Multi-Model Ensemble (NMME) is a multi-agency supported forecasting system for intraseasonal to interannual (ISI) climate predictions. Retrospective forecasts and real-time information are provided by each agency free of charge to facilitate collaborative research efforts for predicting future climate conditions as well as extreme weather events such as floods and droughts. Using the PRISM climate mapping system as the reference data, we examine the skill of five General Circulation Models (GCMs) from the NMME project to forecast monthly and seasonal precipitation and temperature over seven sub-regions of the continental United States. For each model, we quantify the seasonal accuracy of the forecast relative to observed precipitation using the mean square error skill score. This score is decomposed to assess the accuracy of the forecast in the absence of biases (potential skill), and in the presence of conditional (slope reliability) and unconditional (standardized mean error) biases. The quantification of these biases allows us to diagnose each model's skill over a full range temporal and spatial scales. Finally, we test each model's forecasting skill by evaluating its ability to predict extended periods of extreme temperature and precipitation that were conducive to 'billion-dollar' historical flood and drought events in different regions of the continental USA. The forecasting skill of the individual climate models is summarized and presented along with a discussion of different multi-model averaging techniques for predicting such events.

  10. GRACE Assimilation into Hydrological Model Improves Representation of Drought-induced Groundwater Trend over Murray-Darling Basin, Australia

    Science.gov (United States)

    Schumacher, Maike; Forootan, Ehsan; Van Dijk, Albert I. J. M.; Müller Schmied, Hannes; Crosbie, Russell S.; Kusche, Jürgen; Döll, Petra

    2016-04-01

    The Murray-Darling Basin, one of the largest and driest river basins over the world, experienced a long-term drought (over 2003-2009), the so-called Millennium Drought. As a result, the terrestrial water storage in the region decreased, which was attributed to dry meteorological conditions and extensive irrigation for agriculture. We used simulations of the WaterGAP Global Hydrology Model (WGHM) driven by monthly climate fields from the Climate Research Unit's Time Series (CRU TS 3.2) and precipitation data from the Global Precipitation Climatology Center (GPCC) to estimate linear trends in soil, surface and groundwater compartments, as well as total water storage changes (TWSC). However, the model was not able to capture the effect of the Millennium Drought on the storage compartments likely due to missing processes in dry regions or climate forcing uncertainties. Particularly, TWSC simulated by standard WGHM did not reproduce the negative trend during 2003-2009. Therefore, in this study, we investigate whether assimilating TWSC from the Gravity Recovery And Climate Experiment (GRACE) satellite mission into WGHM enables a more realistic representation of the Millennium Drought on the basin hydrology. Firstly, the quality of monthly GRACE TWSC and its post-processing over the Murray-Darling Basin was assessed. An improved calibration and data assimilation (C/DA) approach (Schumacher et al., JoG-2016) was then applied to integrate GRACE TWSC along with its full error covariance information into WGHM during 2003-2009. Independent observations of soil moisture, groundwater and surface water extent were used to validate the model outputs after C/DA. Our investigations indicate that the integration of GRACE data indeed introduces a negative trend to TWSC simulations of WGHM, which occurred predominantly in the south (Murray Basin). The trend was found to be associated with the changes in groundwater storage, which was confirmed through validation with in

  11. Increased drought impacts on temperate rainforests from southern South America: results of a process-based, dynamic forest model.

    Directory of Open Access Journals (Sweden)

    Alvaro G Gutiérrez

    Full Text Available Increased droughts due to regional shifts in temperature and rainfall regimes are likely to affect forests in temperate regions in the coming decades. To assess their consequences for forest dynamics, we need predictive tools that couple hydrologic processes, soil moisture dynamics and plant productivity. Here, we developed and tested a dynamic forest model that predicts the hydrologic balance of North Patagonian rainforests on Chiloé Island, in temperate South America (42°S. The model incorporates the dynamic linkages between changing rainfall regimes, soil moisture and individual tree growth. Declining rainfall, as predicted for the study area, should mean up to 50% less summer rain by year 2100. We analysed forest responses to increased drought using the model proposed focusing on changes in evapotranspiration, soil moisture and forest structure (above-ground biomass and basal area. We compared the responses of a young stand (YS, ca. 60 years-old and an old-growth forest (OG, >500 years-old in the same area. Based on detailed field measurements of water fluxes, the model provides a reliable account of the hydrologic balance of these evergreen, broad-leaved rainforests. We found higher evapotranspiration in OG than YS under current climate. Increasing drought predicted for this century can reduce evapotranspiration by 15% in the OG compared to current values. Drier climate will alter forest structure, leading to decreases in above ground biomass by 27% of the current value in OG. The model presented here can be used to assess the potential impacts of climate change on forest hydrology and other threats of global change on future forests such as fragmentation, introduction of exotic tree species, and changes in fire regimes. Our study expands the applicability of forest dynamics models in remote and hitherto overlooked regions of the world, such as southern temperate rainforests.

  12. SVAT modeling of crop physiological response to drought in potatoes under different types of deficit irrigation

    DEFF Research Database (Denmark)

    Plauborg, Finn; Mollerup, Mikkel; Abrahamsen, Per;

      Further understanding of the crop physiologic responses to drought caused by deficit irrigation (DI), regular or partial root drying (PRD), have been obtained in several studies in tomatoes and potatoes under controlled environment. The improved quantitative description of the production...... in a potato ridge system, which in fact is a 3D structure....

  13. Making the distinction between water scarcity and drought using an observation-modeling framework

    NARCIS (Netherlands)

    Loon, van A.F.; Lanen, van H.A.J.

    2013-01-01

    Drought and water scarcity are keywords for river basin management in water-stressed regions. “Drought” is a natural hazard, caused by large-scale climatic variability, and cannot be prevented by local water management. “Water scarcity” refers to the long-term unsustainable use of water resources, w

  14. Drought in the Anthropocene

    Science.gov (United States)

    van Loon, Anne F.; Gleeson, Tom; Clark, Julian; van Dijk, Albert I. J. M.; Stahl, Kerstin; Hannaford, Jamie; di Baldassarre, Giuliano; Teuling, Adriaan J.; Tallaksen, Lena M.; Uijlenhoet, Remko; Hannah, David M.; Sheffield, Justin; Svoboda, Mark; Verbeiren, Boud; Wagener, Thorsten; Rangecroft, Sally; Wanders, Niko; van Lanen, Henny A. J.

    2016-02-01

    Drought management is inefficient because feedbacks between drought and people are not fully understood. In this human-influenced era, we need to rethink the concept of drought to include the human role in mitigating and enhancing drought.

  15. Probabilistic drought characterization in the categorical form using ordinal regression

    Science.gov (United States)

    Hao, Zengchao; Hong, Yang; Xia, Youlong; Singh, Vijay P.; Hao, Fanghua; Cheng, Hongguang

    2016-04-01

    Drought is an insidious natural hazard that may cause tremendous losses to different sectors, including agriculture and ecosystems. Reliable drought monitoring and early warning are of critical importance for drought preparedness planning and mitigation to reduce potential impacts. Traditional drought monitoring is generally based on drought indices, such as Standardized Precipitation Index (SPI), that are computed from hydro-climatic variables. The U.S. Drought Monitor (USDM) classifies drought conditions into different drought categories to provide composite drought information by integrating multiple drought indices, which has been commonly used to aid decision making at the federal, state, and local levels. Characterizing drought in categories similar to USDM would be important for decision making for both research and operational purposes. However, drought monitoring, based on a variety of drought indices, is challenged by the classification of drought into categories used by USDM. In this study, an ordinal regression model is proposed to characterize droughts in USDM drought categories based on several drought indices, in which the probability of each drought category can be estimated. The proposed method is assessed by comparing with USDM in Texas and a satisfactory performance for estimating drought categories is revealed.

  16. Comparison of rainfall based SPI drought indices with SMDI and ETDI indices derived from a soil water budget model

    Science.gov (United States)

    Houcine, A.; Bargaoui, Z.

    2012-04-01

    Modelling soil water budget is a key issue for assessing drought awareness indices based on soil moisture estimation. The aim of the study is to compare drought indices based on rainfall time series to those based on soil water content time series and evapotranspiration time series. To this end, a vertically averaged water budget over the root zone is implemented to assist the estimation of evapotranspiration flux. A daily time step is adopted to run the water budget model for a lumped watershed of 250 km2 under arid climate where recorded meteorological and hydrological data are available for a ten year period. The water balance including 7 parameters is computed including evapotranspiration, runoff and leakage. Soil properties related parameters are derived according to pedo transfer functions while two remaining parameters are considered as data driven and are subject to calibration. The model is calibrated using daily hydro meteorological data (solar radiation, air temperature, air humidity, mean areal rainfall) as well as daily runoff records and also average annual (or regional) evapotranspiration. The latter is estimated using an empirical sub-model. A set of acceptable solutions is identified according to the values of the Nash coefficients for annual and decadal runoffs as well as the relative bias for average annual evapotranspiration. Using these acceptable solutions several drought indices are computed: SPI (standard precipitation index), SMDI (soil moisture deficit index) and ETDI (evapotranspiration deficit index). While SPI indicators are based only on monthly precipitation time series, SMDI are based on weekly mean soil water content as computed by the hydrological model. On the other hand ETDI indices are based on weekly mean potential and actual evapotranspirations as estimated by the meteorological and hydrological models. For SPI evaluation various time scales are considered from one to twelve months (SPI1, SPI3, SPI6, SPI9 and SPI12). For all

  17. ASSESSMENT OF EARLY SEASON AGRICULTURAL DROUGHT THROUGH LAND SURFACE WATER INDEX (LSWI AND SOIL WATER BALANCE MODEL

    Directory of Open Access Journals (Sweden)

    K. Chandrasekar

    2012-08-01

    Full Text Available An attempt was made to address the early season agriculture drought, by monitoring the surface soil wetness during 2010 cropping seasons in the states of Andhra Pradesh and Tamil Nadu. Short Wave Infrared (SWIR based Land Surface Water Index (LSWI and Soil Water Balance (SWB model using inputs from remote sensing and ancillary data were used to monitor early season agriculture drought. During the crop season, investigation was made on LSWI characteristics and its response to the rainfall. It was observed that the Rate of Increase (RoI of LSWI was the highest during the fortnights when the onset of monsoon occurred. The study showed that LSWI is sensitive to the onset of monsoon and initiation of cropping season. The second part of this study attempted to develop a simple book keeping – bucket type – water tight soil water balance model to derive the top 30cm profile soil moisture using climatic, soil and crop parameters as the basic inputs. Soil moisture derived from the model was used to compute the Area Conducive for Sowing (ACS during the sowing window of the cropping season. The soil moisture was validated spatially and temporally with the ground observed soil moisture values. The ACS was compared with the RoI of LSWI. The results showed that the RoI was high during the sowing window whenever the ACS was greater than 50% of the district area. The observation was consistent in all the districts of the two states. Thus the analysis revealed the potential of LSWI for early season agricultural drought management.

  18. General mechanisms of drought response and their application in drought resistance improvement in plants.

    Science.gov (United States)

    Fang, Yujie; Xiong, Lizhong

    2015-02-01

    Plants often encounter unfavorable environmental conditions because of their sessile lifestyle. These adverse factors greatly affect the geographic distribution of plants, as well as their growth and productivity. Drought stress is one of the premier limitations to global agricultural production due to the complexity of the water-limiting environment and changing climate. Plants have evolved a series of mechanisms at the morphological, physiological, biochemical, cellular, and molecular levels to overcome water deficit or drought stress conditions. The drought resistance of plants can be divided into four basic types-drought avoidance, drought tolerance, drought escape, and drought recovery. Various drought-related traits, including root traits, leaf traits, osmotic adjustment capabilities, water potential, ABA content, and stability of the cell membrane, have been used as indicators to evaluate the drought resistance of plants. In the last decade, scientists have investigated the genetic and molecular mechanisms of drought resistance to enhance the drought resistance of various crops, and significant progress has been made with regard to drought avoidance and drought tolerance. With increasing knowledge to comprehensively decipher the complicated mechanisms of drought resistance in model plants, it still remains an enormous challenge to develop water-saving and drought-resistant crops to cope with the water shortage and increasing demand for food production in the future. PMID:25336153

  19. Probabilistic drought intensification forecasts using temporal patterns of satellite-derived drought indicators

    Science.gov (United States)

    Park, Sumin; Im, Jungho; Park, Seonyeong

    2016-04-01

    A drought occurs when the condition of below-average precipitation in a region continues, resulting in prolonged water deficiency. A drought can last for weeks, months or even years, so can have a great influence on various ecosystems including human society. In order to effectively reduce agricultural and economic damage caused by droughts, drought monitoring and forecasts are crucial. Drought forecast research is typically conducted using in situ observations (or derived indices such as Standardized Precipitation Index (SPI)) and physical models. Recently, satellite remote sensing has been used for short term drought forecasts in combination with physical models. In this research, drought intensification was predicted using satellite-derived drought indices such as Normalized Difference Drought Index (NDDI), Normalized Multi-band Drought Index (NMDI), and Scaled Drought Condition Index (SDCI) generated from Moderate Resolution Imaging Spectroradiometer (MODIS) and Tropical Rainfall Measuring Mission (TRMM) products over the Korean Peninsula. Time series of each drought index at the 8 day interval was investigated to identify drought intensification patterns. Drought condition at the previous time step (i.e., 8 days before) and change in drought conditions between two previous time steps (e.g., between 16 days and 8 days before the time step to forecast) Results show that among three drought indices, SDCI provided the best performance to predict drought intensification compared to NDDI and NMDI through qualitative assessment. When quantitatively compared with SPI, SDCI showed a potential to be used for forecasting short term drought intensification. Finally this research provided a SDCI-based equation to predict short term drought intensification optimized over the Korean Peninsula.

  20. Measuring inflation persistence in Brazil using a multivariate model

    Directory of Open Access Journals (Sweden)

    Vicente da Gama Machado

    2014-06-01

    Full Text Available We estimate inflation persistence in Brazil in a multivariate framework of unobserved components, accounting for the following sources affecting inflation persistence: Deviations of expectations from the actual policy target; persistence of the factors driving inflation; and the usual intrinsic measure of persistence, evaluated through lagged inflation terms. Data on inflation, output and interest rates are decomposed into unobserved components. To simplify the estimation of a great number of unknown variables, we employ Bayesian analysis. Our results indicate that expectations-based persistence matters considerably for inflation persistence in Brazil.

  1. Improved Analyses and Forecasts of Snowpack, Runoff and Drought through Remote Sensing and Land Surface Modeling in Southeastern Europe

    Science.gov (United States)

    Matthews, D.; Brilly, M.; Gregoric, G.; Polajnar, J.; Kobold, M.; Zagar, M.; Knoblauch, H.; Staudinger, M.; Mecklenburg, S.; Lehning, M.; Schweizer, J.; Balint, G.; Cacic, I.; Houser, P.; Pozzi, W.

    2008-12-01

    European hydrometeorological services and research centers are faced with increasing challenges from extremes of weather and climate that require significant investments in new technology and better utilization of existing human and natural resources to provide improved forecasts. Major advances in remote sensing, observation networks, data assimilation, numerical modeling, and communications continue to improve our ability to disseminate information to decision-makers and stake holders. This paper identifies gaps in current technologies, key research and decision-maker teams, and recommends means for moving forward through focused applied research and integration of results into decision support tools. This paper reports on the WaterNet - NASA Water Cycle Solutions Network contacts in Europe and summarizes progress in improving water cycle related decision-making using NASA research results. Products from the Hydrologic Sciences Branch, Goddard Space Flight Center, NASA, Land Information System's (LIS) Land Surface Models (LSM), the SPoRT, CREW , and European Space Agency (ESA), and Joint Research Center's (JRC) natural hazards products, and Swiss Federal Institute for Snow and Avalanche Research's (SLF), and others are discussed. They will be used in collaboration with the ESA and the European Commission to provide solutions for improved prediction of water supplies and stream flow, and droughts and floods, and snow avalanches in the major river basins serviced by EARS, ZAMG, SLF, Vituki Consult, and other European forecast centers. This region of Europe includes the Alps and Carpathian Mountains and is an area of extreme topography with abrupt 2000 m mountains adjacent to the Adriatic Sea. These extremes result in the highest precipitation ( > 5000 mm) in Europe in Montenegro and low precipitation of 300-400 mm at the mouth of the Danube during droughts. The current flood and drought forecasting systems have a spatial resolution of 9 km, which is currently being

  2. Mathematical Modeling Applied to Prediction of Landslides in Southern Brazil

    Science.gov (United States)

    Silva, Lúcia; Araújo, João; Braga, Beatriz; Fernandes, Nelson

    2013-04-01

    Mass movements are natural phenomena that occur on the slopes and are important agents working in landscape development. These movements have caused serious damage to infrastructure and properties. In addition to the mass movements occurring in natural slopes, there is also a large number of accidents induced by human action in the landscape. The change of use and land cover for the introduction of agriculture is a good example that have affected the stability of slopes. Land use and/or land cover changes have direct and indirect effects on slope stability and frequently represent a major factor controlling the occurrence of man-induced mass movements. In Brazil, especially in the southern and southeastern regions, areas of original natural rain forest have been continuously replaced by agriculture during the last decades, leading to important modifications in soil mechanical properties and to major changes in hillslope hydrology. In these regions, such effects are amplified due to the steep hilly topography, intense summer rainfall events and dense urbanization. In November 2008, a major landslide event took place in a rural area with intensive agriculture in the state of Santa Catarina (Morro do Baú) where many catastrophic landslides were triggered after a long rainy period. In this area, the natural forest has been replaced by huge banana and pine plantations. The state of Santa Catarina in recent decades has been the scene of several incidents of mass movements such as this catastrophic event. In this study, based on field mapping and modeling, we characterize the role played by geomorphological and geological factors in controlling the spatial distribution of landslides in the Morro do Baú area. In order to attain such objective, a digital elevation model of the basin was generated with a 10m grid in which the topographic parameters were obtained. The spatial distribution of the scars from this major event was mapped from another image, obtained immediately

  3. Forest biogeochemistry in response to drought.

    Science.gov (United States)

    Schlesinger, William H; Dietze, Michael C; Jackson, Robert B; Phillips, Richard P; Rhoades, Charles C; Rustad, Lindsey E; Vose, James M

    2016-07-01

    Trees alter their use and allocation of nutrients in response to drought, and changes in soil nutrient cycling and trace gas flux (N2 O and CH4 ) are observed when experimental drought is imposed on forests. In extreme droughts, trees are increasingly susceptible to attack by pests and pathogens, which can lead to major changes in nutrient flux to the soil. Extreme droughts often lead to more common and more intense forest fires, causing dramatic changes in the nutrient storage and loss from forest ecosystems. Changes in the future manifestation of drought will affect carbon uptake and storage in forests, leading to feedbacks to the Earth's climate system. We must improve the recognition of drought in nature, our ability to manage our forests in the face of drought, and the parameterization of drought in earth system models for improved predictions of carbon uptake and storage in the world's forests. PMID:26403995

  4. Drought limitations to leaf-level gas exchange: results from a model linking stomatal optimization and cohesion-tension theory.

    Science.gov (United States)

    Novick, Kimberly A; Miniat, Chelcy F; Vose, James M

    2016-03-01

    We merge concepts from stomatal optimization theory and cohesion-tension theory to examine the dynamics of three mechanisms that are potentially limiting to leaf-level gas exchange in trees during drought: (1) a 'demand limitation' driven by an assumption of optimal stomatal functioning; (2) 'hydraulic limitation' of water movement from the roots to the leaves; and (3) 'non-stomatal' limitations imposed by declining leaf water status within the leaf. Model results suggest that species-specific 'economics' of stomatal behaviour may play an important role in differentiating species along the continuum of isohydric to anisohydric behaviour; specifically, we show that non-stomatal and demand limitations may reduce stomatal conductance and increase leaf water potential, promoting wide safety margins characteristic of isohydric species. We used model results to develop a diagnostic framework to identify the most likely limiting mechanism to stomatal functioning during drought and showed that many of those features were commonly observed in field observations of tree water use dynamics. Direct comparisons of modelled and measured stomatal conductance further indicated that non-stomatal and demand limitations reproduced observed patterns of tree water use well for an isohydric species but that a hydraulic limitation likely applies in the case of an anisohydric species.

  5. A Distributed Multi-dimensional SOLAP Model of Remote Sensing Data and Its Application in Drought Analysis

    Directory of Open Access Journals (Sweden)

    LI Jiyuan

    2014-06-01

    Full Text Available SOLAP (Spatial On-Line Analytical Processing has been applied to multi-dimensional analysis of remote sensing data recently. However, its computation performance faces a considerable challenge from the large-scale dataset. A geo-raster cube model extended by Map-Reduce is proposed, which refers to the application of Map-Reduce (a data-intensive computing paradigm in the OLAP field. In this model, the existing methods are modified to adapt to distributed environment based on the multi-level raster tiles. Then the multi-dimensional map algebra is introduced to decompose the SOLAP computation into multiple distributed parallel map algebra functions on tiles under the support of Map-Reduce. The drought monitoring by remote sensing data is employed as a case study to illustrate the model construction and application. The prototype is also implemented, and the performance testing shows the efficiency and scalability of this model.

  6. Drought in a human-modified world: reframing drought definitions, understanding, and analysis approaches

    Science.gov (United States)

    Van Loon, Anne F.; Stahl, Kerstin; Di Baldassarre, Giuliano; Clark, Julian; Rangecroft, Sally; Wanders, Niko; Gleeson, Tom; Van Dijk, Albert I. J. M.; Tallaksen, Lena M.; Hannaford, Jamie; Uijlenhoet, Remko; Teuling, Adriaan J.; Hannah, David M.; Sheffield, Justin; Svoboda, Mark; Verbeiren, Boud; Wagener, Thorsten; Van Lanen, Henny A. J.

    2016-09-01

    are considered normal or reference conditions) over time? Answering these questions requires exploration of qualitative and quantitative data as well as mixed modelling approaches. The challenges related to drought research and management in the Anthropocene are not unique to drought, but do require urgent attention. We give recommendations drawn from the fields of flood research, ecology, water management, and water resources studies. The framework presented here provides a holistic view on drought in the Anthropocene, which will help improve management strategies for mitigating the severity and reducing the impacts of droughts in future.

  7. Drought characteristics and related risks in large and mesoscale tropical catchments in Latin-America and South East Asia

    Science.gov (United States)

    Nauditt, Alexandra; Ribbe, Lars; Birkel, Christian; Célleri, Rolando

    2016-04-01

    Seasonal meteorological and hydrological droughts are a recurrent phenomenon in water abundant tropical countries and are expected to become more frequent in the future. Unusual water shortage in the past months and years has severely affected societies living in the Paraiba do Sul river basin (Brazil), the Mekong, as well as in a number of basins in Central America and Vietnam among many others. Preparedness, however, is absent and site appropriate water management measures and strategies are not available. While drought related research and water management in recent years has been widely addressed in water scarce subtropical regions, the US and Europe, not much attention has been paid to drought risk in tropical catchments. Available daily or monthly precipitation and runoff time series for catchments in Brazil, Costa Rica, Ecuador, the Mekong region and Vietnam were analysed to compare historical meteorological and hydrological drought frequency (SPI/SRI). The role of tropical catchment characteristics, storage and climate variability in seasonal drought evolvement was investigated by applying the conceptual semi-distributed HBV light model to two undisturbed catchments in Central Vietnam and 18 catchments of a size of 70-5000 km² in Costa Rica. For the Mekong and the Paraíba de Sul, the hydrological module of the WEAP model was applied to undisturbed subcatchments with the same objective. To understand and separate the anthropogenic impact on drought evolvement, the abstractions (irrigation, reservoirs, water supply) and hydrological alterations were observed and quantified by applying water allocation and balance model WEAP. We conclude that such a combined model-data analysis that equally accounts for landscape related and anthropogenic impacts on the local hydrological cycle is a useful approach for drought management in tropical countries.

  8. Using Search Algorithms and Probabilistic Graphical Models to Understand the Influence of Atmospheric Circulation on Western US Drought

    Science.gov (United States)

    Malevich, S. B.; Woodhouse, C. A.

    2015-12-01

    This work explores a new approach to quantify cool-season mid-latitude circulation dynamics as they relate western US streamflow variability and drought. This information is used to probabilistically associate patterns of synoptic atmospheric circulation with spatial patterns of drought in western US streamflow. Cool-season storms transport moisture from the Pacific Ocean and are a primary source for western US streamflow. Studies overthe past several decades have emphasized that the western US hydroclimate is influenced by the intensity and phasing of ocean and atmosphere dynamics and teleconnections, such as ENSO and North Pacific variability. These complex interactions are realized in atmospheric circulation along the west coast of North America. The region's atmospheric circulation can encourage a preferential flow in winter storm tracks from the Pacific, and thus influence the moisture conditions of a given river basin over the course of the cool season. These dynamics have traditionally been measured with atmospheric indices based on values from fixed points in space or principal component loadings. This study uses collective search agents to quantify the position and intensity of potentially non-stationary atmosphere features in climate reanalysis datasets, relative to regional hydrology. Results underline the spatio-temporal relationship between semi-permanent atmosphere characteristics and naturalized streamflow from major river basins of the western US. A probabilistic graphical model quantifies this relationship while accounting for uncertainty from noisy climate processes, and eventually, limitations from dataset length. This creates probabilities for semi-permanent atmosphere features which we hope to associate with extreme droughts of the paleo record, based on our understanding of atmosphere-streamflow relations observed in the instrumental record.

  9. Observed and modeled ecosystem isoprene fluxes from an oak-dominated temperate forest and the influence of drought stress

    Energy Technology Data Exchange (ETDEWEB)

    Potosnak, M.; LeStourgeon, Lauren; Pallardy, Stephen G.; Hosman, Kevin P.; Gu, Lianghong; Karl, Thomas; Geron, Chris; Guenther, Alex B.

    2014-02-19

    Ecosystem fluxes of isoprene emission were measured during the majority of the 2011 growing season at the University of Missouri's Baskett Wildlife Research and Education Area in centralMissouri, USA (38.7° N, 92.2° W). This broadleaf deciduous forest is typical of forests common in theOzarks region of the central United States. The goal of the isoprene flux measurements was to test ourunderstanding of the controls on isoprene emission from the hourly to the seasonal timescale using a state-of-the-art emission model, MEGAN (Model of Emissions of Gases and Aerosols from Nature). Isoprene emission rates were very high from the forest with a maximum of 50.9 mg m-2 hr-1 (208 nmol m-2 s-1), which to our knowledge exceeds all other reports of canopy-scale isoprene emission. The fluxes showed a clear dependence on the previous temperature and light regimes which was successfully captured by the existing algorithms in MEGAN. During a period of drought, MEGAN was unable to reproduce the time-dependent response of isoprene emission to water stress. Overall, the performance of MEGAN was robust and could explain 87% of the observed variance in the measured fluxes, but the response of isoprene emission to drought stress is a major source of uncertainty.

  10. Drought as a natural disaster

    Energy Technology Data Exchange (ETDEWEB)

    Maybank, J. [Agvironics Consulting, SK (Canada); Bonsal, B. [Saskatchewan Univ., Saskatoon, SK (Canada). Dept. of Geography; Jones, K. [Environment Canada, Downsview, ON (Canada). Canadian Climate Centre; Lawford, R. [Canadian Climate Centre, Saskatoon, SK (Canada). National Hydrology Research Centre; O`Brien, E.G. [Agriculture Canada, Ottawa, ON (Canada). Energy Analysis and Policy Div.; Ripley, E.A. [Saskatchewan Univ., Saskatoon, SK (Canada). Dept. of Soil Science; Wheaton, E. [Saskatchewan Research Council, Saskatoon, SK (Canada)

    1995-12-31

    A discussion of droughts as a major natural disaster in dry areas such as the Canadian Prairies where precipitation patterns are seasonal, was presented. Environmental damages include soil degradation and erosion, vegetation damage, slough and lake deterioration and wildlife loss. The development and application of specific soil moisture and drought indices based on cumulative precipitation deficits have enhanced drought monitoring programs. The identification of precursor conditions raises the possibility that the likelihood of a drought occurring in a particular year or growing season might be predictable. The ability to forecast seasonal temperature and precipitation anomalies is potentially feasible using a suitable merging of precursor parameters and modelling methodologies. Research activity to identify and evaluate new mitigative measure should be increased to keep pace with the prospects of drought predictability. 90 refs., 1 tab., 7 figs.

  11. Drought, Sustainability, and the Law

    Directory of Open Access Journals (Sweden)

    Robert W. Adler

    2010-07-01

    Full Text Available Researchers and responsible officials have made considerable progress in recent years in efforts to anticipate, plan for, and respond to drought. Some of those efforts are beginning to shift from purely reactive, relief-oriented measures to programs designed to prevent or to mitigate drought impacts. Considerably less attention has been given to laws that may affect practices and policies that either increase or decrease drought vulnerability. Water law regimes, drought response and relief legislation, and laws governing broader but related issues of economic policy—especially agricultural policy—should be evaluated more comprehensively to enhance incentives for more ―water sustainable‖ practices in agriculture and other sectors of the economy. Those changes will be increasingly important if current climate change models are correct in their prediction that many parts of the world can expect more frequent and more severe conditions of meteorological drought in the ensuing decades.

  12. Propagation of model and forcing uncertainty into hydrological drought characteristics in a multi-model century-long experiment in continental river basins

    Science.gov (United States)

    Samaniego, L. E.; Kumar, R.; Schaefer, D.; Huang, S.; Yang, T.; Mishra, V.; Eisner, S.; Vetter, T.; Pechlivanidis, I.; Liersch, S.; Flörke, M.; Krysanova, V.

    2015-12-01

    Droughts are creeping hydro-meteorological events that bring societiesand natural systems to their limits and inducing considerablesocio-economic losses. Currently it is hypothesized that climate changewill exacerbate current trends leading a more severe and extendeddroughts, as well as, larger than normal recovery periods. Currentassessments, however, lack of a consistent framework to deal withcompatible initial conditions for the impact models and a set ofstandardized historical and future forcings. The ISI-MIP project provides an unique opportunity to understand thepropagation of model and forcing uncertainty into century-long timeseries of drought characteristics using an ensemble of model predictionsacross a broad range of climate scenarios and regions. In the presentstudy, we analyze this issue using the hydrologic simulations carriedout with HYPE, mHM, SWIM, VIC, and WaterGAP3 in seven large continentalriver basins: Amazon, Blue Nile, Ganges, Niger, Mississippi, Rhine,Yellow. All models are calibrated against observed streamflow duringthe period 1971-2001 using the same forcings based on the WATCH datasets. These constrained models were then forced with bias correctedoutputs of five CMIP-5 GCMs under four RCP scenarios (i.e. 2.6, 4.5,6.0, and 8.5 W/m2) for the period 1971-2099. A non-parametric kernel density approach is used to estimate thetemporal evolution of a monthly runoff index based on simulatedstreamflow. Hydrologic simulations corresponding to each GCM during thehistoric period of 1981-2010 serve as reference for the estimation ofthe basin specific monthly probability distribution functions. GCMspecific reference pdfs are then used to recast the future hydrologicmodel outputs from different RCP scenarios. Based on these results,drought severity and duration are investigated during periods: 1)2006-2035, 2) 2036-2065 and 3) 2070-2099. Two main hypothesis areinvestigated: 1) model predictive uncertainty of drought indices amongdifferent hydrologic

  13. Land Reform in Brazil: the arrival of the market model

    OpenAIRE

    Lambais, Guilherme B. R.

    2008-01-01

    In this work I will analyze past and current agrarian public policy concerning land redistribution in Brazil. Firstly, to understand the current land tenure situation the introduction will provide a description of the overall unequal land distribution. Secondly, a comparative analysis of the state-led land reform and the market-led land reform will establish the differences between the two approaches at light of land reform as a public policy tool. A historical review of the state-led land re...

  14. Epidemiology of extrapulmonary tuberculosis in Brazil: a hierarchical model

    OpenAIRE

    Gomes, Teresa; Reis-Santos, Bárbara; Bertolde, Adelmo; Johnson, John L.; Riley, Lee W.; Maciel, Ethel Leonor

    2014-01-01

    Background Although extrapulmonary tuberculosis (EPTB) is less frequent than Pulmonary Tuberculosis (PTB) and is a secondary target for national TB control programs, its significance has increased worldwide during the HIV epidemic. The objective of this study was to examine the epidemiology of EPTB in Brazil between 2007 and 2011. Methods Cross-sectional study involving all cases of TB reported to the Brazilian Notifiable Diseases Surveillance System (Sistema de Informações de Agravo de Notif...

  15. Six-month lead downscaling prediction of winter-spring drought in South Korea based on multi-model ensemble

    Science.gov (United States)

    Sohn, Soo-Jin; Ahn, Joong-Bae; Tam, Chi-Yung

    2013-04-01

    Given the changing climate, advance information on hydrological extremes such as droughts will help in planning for disaster mitigation and facilitate better decision making for water availability management. A deficit of precipitation for long-term time scales beyond 6 months has impacts on the hydrological sectors such as ground water, streamflow, and reservoir storage. The potential of using a dynamical-statistical method for long-lead drought prediction was investigated. In particular, the APEC Climate Center (APCC) 1-Tier multi-model ensemble (MME) was downscaled for predicting the standardized precipitation evapotranspiration index (SPEI) over 60 stations in South Korea. SPEI depends on both of precipitation and temperature, and can incorporate the impact of global warming on the balance between precipitation and evapotranspiration. It was found that 1-Tier MME has difficulties in capturing the local temperature and rainfall variations over extratropical land areas, and has no skill in predicting SPEI during boreal winter and spring. On the other hand, temperature and precipitation predictions were substantially improved in the downscaled MME (DMME). In conjunction with variance inflation, DMME can give reasonably skillful six-month-lead forecasts of SPEI for the winter-to-spring period. The results could potentially improve hydrological extreme predictions using meteorological forecasts for policymaker and stakeholders in water management sector for better climate adaption.

  16. 3-D Hydraulic Model Testing of the New Roundhead in Suape, Brazil

    DEFF Research Database (Denmark)

    Andersen, Thomas Lykke; Burcharth, Hans F.; Sipavicius, A.;

    This report deals with a three-dimensional model test study of the extension of the breakwater in Suape, Brazil. The roundhead was tested for stability in various sea conditions. The length scale used for the model tests was 1:35. Unless otherwise specified all values given in this report...

  17. Linking Drought Information to Crop Yield

    Science.gov (United States)

    Madadgar, S.; Farahmand, A.; Li, L.; Aghakouchak, A.

    2015-12-01

    Droughts have detrimental impacts on agricultural yields all over the world every year. This study analyzes the relationship between three drought indicators including Standardized Precipitation Index (SPI); Standardized Soil Moisture Index (SSI), Multivariate Standardized Drought Index (MSDI) and the yields of five largest rain-fed crops in Australia (wheat, broad beans, canola, lupins and barley). Variation of the five chosen crop yields is overall in agreement with the three drought indicators SPI, SSI, and MSDI during the analysis period of 1980-2012. This study develops a bivariate copula model to investigate the statistical dependence of drought and crop yield. Copula functions are used to establish the existing connections between climate variables and crop yields during the Millennium drought in Australia. The proposed model estimates the likelihood of crop yields given the observed or predicted drought indicators SPI, SSI or MSDI. The results are also useful to estimate crop yields associated with different thresholds of precipitation or soil moisture.

  18. Geocomputation and Spatial Modelling for Geographical Drought Risk Assessment: A Case Study of the Hustopeče Area, Czech Republic

    Science.gov (United States)

    Ruda, Aleš; Kolejka, Jaromír; Batelková, Kateřina

    2016-04-01

    The phenomenon of drought is serious in many landscapes with continental patterns of climate. In fact, drought risk is usually assessed in terms of prevailing issue (meteorological, hydrological, agronomical, etc.) and not in terms of complex landscape features. A procedure for detailed geographical drought risk modelling has been developed using recent meteorological data of dry period and prior precipitations, as well as a digital elevation model and geographic data layers of natural landscape features and land cover. The current version of the procedure starts with meteorological data (temperature and precipitation) processing followed by the use of soil and geological data and land cover, the national CORINE LC 2006 CZ database, for assessing the impact of the local natural features on drought risk. The methodology is based on GIS tools, geodata of the geological structure of the area (water holding capacity of the substrate, the horizontal and vertical water conductivity), soil cover (in agricultural and forested areas, soil types and kinds), landscape cover (land use), relief (digital elevation model and its derivatives), temperature and precipitation data from neighbouring representative meteorological and climate stations. The procedure uses regression equation for temperature and precipitation risk modelling, fuzzy standardization for estimation of different water retention within land cover categories and expert estimation for risk categories within rocks and soils. The final calculation is based on spatial decision-making techniques, especially the weighted sum method with a natural breaks reclassification algorithm. Combining geodata of soils, the geological environment and the active surface with their computed humidity conditions, it is possible to identify areas with a graded risk of geographic drought. The final results do not represent partial values, but identify five risk classes in the study area illustrating a possible level of geographical

  19. Effects of heat and drought on carbon and water dynamics in a regenerating semi-arid pine forest: a combined experimental and modeling approach

    Directory of Open Access Journals (Sweden)

    N. K. Ruehr

    2014-01-01

    Full Text Available Increasing summer temperatures and a reduction in precipitation will enhance drought stress in Mediterranean and semi-arid ecosystems. Predicting the net effects on forests' carbon and water balance will depend on our ability to disentangle the sensitivity of component fluxes responding to increasing soil and atmospheric drought. Here we studied carbon and water dynamics in a semi-arid regenerating ponderosa pine forest using field observations and process based modeling. Field observations of two summer dry seasons were used to calibrate a soil-plant-atmosphere (SPA model. In addition, the ecosystem's response to reduced soil drought was quantified based on a field watering experiment and evaluated with the model. Further, the SPA model was used to estimate the relative effects of increasing soil and atmospheric drought over time, by simulating temperature and precipitation scenarios for 2040 and 2080. The seasonality and drought response of ecosystem fluxes was well captured by the calibrated SPA model. Dramatic increases in summer water availability during seasonal drought had a small effect on pine physiology in both the watering experiment and the model. This clearly demonstrates that atmospheric drought induced a strong limitation on carbon uptake in young ponderosa pine due to tight regulation of stomatal conductance. Moreover, simulations showed that net ecosystem exchange (NEE and gross primary productivity (GPP were about three times more affected by summer heat and increased evaporative demand than by reductions in summer precipitation. Annual NEE decreased by 38% in response to extreme summer conditions as predicted to occur in 2080 (June–August: +4.5 °C, because of a strong decline in GPP (−17% while heterotrophic respiration was relatively unaffected (−1%. Considering warming trends across all seasons (September–May: +3 °C and June–August: +4.5 °C, the negative drought effects were largely compensated by an earlier

  20. Drought in the Anthropocene

    OpenAIRE

    van Loon, Anne; Gleeson, Tom; Clark, Julian; Van Dijk, Albert I J M; Stahl, Kerstin; Hannaford, Jamie; Di Baldassarre, Giuliano; Teuling, Adriaan J; Tallaksen, Lena M.; Uijlenhoet, Remko; Hannah, David M.; Sheffield, Justin; Svoboda, Mark; Verbeiren, Boud; Wagener, Thorsten

    2016-01-01

    Droughts are having major impacts around the world. Effective drought management is impeded by a lack of understanding of feedbacks between drought and people. In this human-influenced era, we need to rethink the concept of drought to include the role of people in mitigating or enhancing drought

  1. Management Options During the 2011-2012 Drought on the Apalachicola River: A Systems Dynamic Model Evaluation

    Science.gov (United States)

    Leitman, S.; Pine, W. E.; Kiker, G.

    2016-08-01

    The Apalachicola-Chattahoochee-Flint River basin (ACF) is a large watershed in the southeastern United States. In 2012, the basin experienced the second year of a severe drought and the third multi-year drought in the last 15 years. During severe droughts, low reservoir and river levels can cause economic and ecological impacts to the reservoir, river, and estuarine ecosystems. During drought, augmenting Apalachicola River discharge through upstream reservoir releases and demand management are intuitive and often-suggested solutions to minimizing downstream effects. We assessed whether the existing reservoir system could be operated to minimize drought impacts on downstream water users and ecosystems through flow augmentation. Our analysis finds that in extreme drought such as observed during 2012, increases in water releases from reservoir storage are insufficient to even increase Apalachicola River discharge to levels observed in the 2007 drought. This suggests that there is simply not enough water available in managed storage to offset extreme drought events. Because drought frequency and intensity is predicted to increase under a variety of climate forecasts, our results demonstrate the need for a critical assessment of how water managers will meet increasing water demands in the ACF. Key uncertainties that should be addressed include (1) identifying the factors that led to extremely low Flint River discharge in 2012, and (2) determining how water "saved" via demand management is allocated to storage or passed to downstream ecosystem needs as part of the ongoing revisions to the ACF Water Control Manual by the US Army Corps of Engineers.

  2. Modeling rain-fed maize vulnerability to droughts using the standardized precipitation index from satellite estimated rainfall—Southern Malawi case study

    Science.gov (United States)

    Funk, Christopher C.; Verdin, James; Adams Chavula,; Gregory J. Husak,; Harikishan Jayanthi,; Tamuka Magadzire,

    2013-01-01

    During 1990s, disaster risk reduction emerged as a novel, proactive approach to managing risks from natural hazards. The World Bank, USAID, and other international donor agencies began making efforts to mainstream disaster risk reduction in countries whose population and economies were heavily dependent on rain-fed agriculture. This approach has more significance in light of the increasing climatic hazard patterns and the climate scenarios projected for different hazard prone countries in the world. The Famine Early Warning System Network (FEWS NET) has been monitoring the food security issues in the sub-Saharan Africa, Asia and in Haiti. FEWS NET monitors the rainfall and moisture availability conditions with the help of NOAA RFE2 data for deriving food security status in Africa. This paper highlights the efforts in using satellite estimated rainfall inputs to develop drought vulnerability models in the drought prone areas in Malawi. The satellite RFE2 based SPI corresponding to the critical tasseling and silking phases (in the months of January, February, and March) were statistically regressed with drought-induced yield losses at the district level. The analysis has shown that the drought conditions in February and early March lead to most damage to maize yields in this region. The district-wise vulnerabilities to drought were upscaled to obtain a regional maize vulnerability model for southern Malawi. The results would help in establishing an early monitoring mechanism for drought impact assessment, give the decision makers additional time to assess seasonal outcomes, and identify potential food-related hazards in Malawi.

  3. Modeling the Impacts of Historic Climate Change and Extreme Droughts on Water Yield and Productivity of National Forests over the Conterminous U.S

    Science.gov (United States)

    Sun, S.; Sun, G.; Caldwell, P. V.; McNulty, S. G.; Zhang, Y.

    2014-12-01

    Quantifying the impacts of droughts on the U.S National Forests (NFs) is necessary to develop sound forest management plans to mitigate and adapt to climate change. This study applied a water balance model (WaSSI) to 170 National Forests (NFs) over the conterminous U.S to examine how long-term climatic change and extreme climate events impacted forest water yield and productivity. Our model predicted that mean water yield decreased by 5% while mean productivity increased by 10% between 1961-2012 across the NFs. Overall 32% of NFs showed a significant increasing trend in forest gross ecosystem productivity (GEP), while 5% of the NFs had a significant decreasing trend. This study also suggested that the extent and severity of drought events occurring in the NFs had an increasing trend during the past 50 years. Taking the 170 NFs as a whole, the top-five droughts were characterized by a 261 mm/yr (or 30%) reduction in precipitation, that resulted in reductions in evapotranspiration by 55 mm/yr (or 10%), water yield by 154 mm/yr (or 49%) and GEP by 121 gC/m2/yr (or 10%). However, distribution of these changes varied spatially due to differences in vegetation types, weather, and geography. Overall, this study provided an assessment of historical impacts of droughts on forest watershed hydrology and productivity across diverse geographic regions using a consistent database. The study also identified forest watersheds that were severely influenced by historical drought, and provided a reference to develop appropriate adaptation strategies for potential future extreme droughts on the forest ecosystem services of NFs.

  4. Plant adaptation to drought stress

    Science.gov (United States)

    Basu, Supratim; Ramegowda, Venkategowda; Kumar, Anuj; Pereira, Andy

    2016-01-01

    Plants in their natural habitats adapt to drought stress in the environment through a variety of mechanisms, ranging from transient responses to low soil moisture to major survival mechanisms of escape by early flowering in absence of seasonal rainfall. However, crop plants selected by humans to yield products such as grain, vegetable, or fruit in favorable environments with high inputs of water and fertilizer are expected to yield an economic product in response to inputs. Crop plants selected for their economic yield need to survive drought stress through mechanisms that maintain crop yield. Studies on model plants for their survival under stress do not, therefore, always translate to yield of crop plants under stress, and different aspects of drought stress response need to be emphasized. The crop plant model rice ( Oryza sativa) is used here as an example to highlight mechanisms and genes for adaptation of crop plants to drought stress. PMID:27441087

  5. a Brazilian Vulnerability Index to Natural Disasters of Drought - in the Context of Climate Change

    Science.gov (United States)

    Camarinha, P. I., Sr.; Debortoli, N. S.; Hirota, M.

    2015-12-01

    Droughts are characterized as one of the main types of natural disasters that occur in Brazil. During the 1991-2012, droughts affected more than 14 million Brazilians, so that the concern for the following decades is about the potential impacts triggered by climate change. To analyze the vulnerability of the Brazilian municipalities to drought disasters, we have assessed the effects of climate change to droughts until the end of 21th century. A composite index was created based on three different dimensions: i) Exposure, represented by climate anomalies related to the drought process, such as changes in accumulated rainfall averages, interannual variability of rainfall, and the frequency and magnitude of severe droughts (measured by the Standardized Precipitation-Evapotranspiration Index); ii) Sensitivity, encompassing socioeconomic, demographic, land use and water management data; iii) Adaptive Capacity, consisting of socioeconomic and institutional data from Brazilian municipalities, such as the Human Development Index (HDI), social inequality (Gini index) and illiteracy rate. The climate variables used in this study are results from simulations of the Regional Climate Model Eta (with a downscaling of 20km spatial resolution) nested with two global climate models (HadGEM ES and MIROC 5) and was provided by National Institute for Space Research. The baseline period was 1961-1990 and future periods was 2011-2040; 2041-2070 and 2071-2099. For the simulations of future climate it was used the 4.5 and 8.5 IPCC/AR5 RCP (Representative Concentration Pathways) scenarios. All variables used in this study was handled, exploited and related in a Geographic Information System (GIS). The methodology allowed the identification of vulnerability hotspots, the targeting of adaptation strategies and the development of public policy to minimize the potential impacts of future droughts. The final results (see attached image) indicate that the most vulnerable regions are located in

  6. The role of CSP in Brazil: A multi-model analysis

    Science.gov (United States)

    Soria, Rafael; Lucena, André F. P.; Tomaschek, Jan; Fichter, Tobias; Haasz, Thomas; Szklo, Alexandre; Schaeffer, Roberto; Rochedo, Pedro; Fahl, Ulrich; Kern, Jürgen; Hoffmann, Susanne

    2016-05-01

    MESSAGE, TIMES and REMIX-CEM are potential tools for modelling a larger penetration of variable renewable energy (VRE) into the Brazilian power system. They also allow devising the opportunities that concentrated solar power (CSP) plants offer to the power system and to the wider energy system. There are different opportunities for CSP in Brazil in the short and medium term, consolidating this technology as a feasible alternative for greenhouse gas (GHG) mitigation in Brazil. This work verified that CSP is a cost-effective option only under very stringent mitigation scenarios (4DS and 2DS) and when carbon capture and storage (CCS) is not available. Still, according to the findings of REMIX-CEM-B, CSP can provide firm energy and dispatchable capacity in the Northeast region of Brazil, optimally complementing wind and PV generation. Moreover, CSP can offer additional flexibility to the Northeast power system, especially during winter and after 2030.

  7. Assimilation of GRACE Terrestrial Water Storage into a Land Surface Model: Evaluation 1 and Potential Value for Drought Monitoring in Western and Central Europe

    Science.gov (United States)

    Li, Bailing; Rodell, Matthew; Zaitchik, Benjamin F.; Reichle, Rolf H.; Koster, Randal D.; van Dam, Tonie M.

    2012-01-01

    A land surface model s ability to simulate states (e.g., soil moisture) and fluxes (e.g., runoff) is limited by uncertainties in meteorological forcing and parameter inputs as well as inadequacies in model physics. In this study, anomalies of terrestrial water storage (TWS) observed by the Gravity Recovery and Climate Experiment (GRACE) satellite mission were assimilated into the NASA Catchment land surface model in western and central Europe for a 7-year period, using a previously developed ensemble Kalman smoother. GRACE data assimilation led to improved runoff correlations with gauge data in 17 out of 18 hydrological basins, even in basins smaller than the effective resolution of GRACE. Improvements in root zone soil moisture were less conclusive, partly due to the shortness of the in situ data record. In addition to improving temporal correlations, GRACE data assimilation also reduced increasing trends in simulated monthly TWS and runoff associated with increasing rates of precipitation. GRACE assimilated root zone soil moisture and TWS fields exhibited significant changes in their dryness rankings relative to those without data assimilation, suggesting that GRACE data assimilation could have a substantial impact on drought monitoring. Signals of drought in GRACE TWS correlated well with MODIS Normalized Difference Vegetation Index (NDVI) data in most areas. Although they detected the same droughts during warm seasons, drought signatures in GRACE derived TWS exhibited greater persistence than those in NDVI throughout all seasons, in part due to limitations associated with the seasonality of vegetation.

  8. Evaluation of strategies for nature-based solutions to drought: a decision support model at the national scale

    Science.gov (United States)

    Simpson, Mike; Ives, Matthew; Hall, Jim

    2016-04-01

    There is an increasing body of evidence in support of the use of nature based solutions as a strategy to mitigate drought. Restored or constructed wetlands, grasslands and in some cases forests have been used with success in numerous case studies. Such solutions remain underused in the UK, where they are not considered as part of long-term plans for supply by water companies. An important step is the translation of knowledge on the benefits of nature based solutions at the upland/catchment scale into a model of the impact of these solutions on national water resource planning in terms of financial costs, carbon benefits and robustness to drought. Our project, 'A National Scale Model of Green Infrastructure for Water Resources', addresses this issue through development of a model that can show the costs and benefits associated with a broad roll-out of nature based solutions for water supply. We have developed generalised models of both the hydrological effects of various classes and implementations of nature-based approaches and their economic impacts in terms of construction costs, running costs, time to maturity, land use and carbon benefits. Our next step will be to compare this work with our recent evaluation of conventional water infrastructure, allowing a case to be made in financial terms and in terms of security of water supply. By demonstrating the benefits of nature based solutions under multiple possible climate and population scenarios we aim to demonstrate the potential value of using nature based solutions as a component of future long-term water resource plans. Strategies for decision making regarding the selection of nature based and conventional approaches, developed through discussion with government and industry, will be applied to the final model. Our focus is on keeping our work relevant to the requirements of decision-makers involved in conventional water planning. We propose to present the outcomes of our model for the evaluation of nature

  9. Future discharge drought across climate regions around the world modelled with a synthetic hydrological modelling approach forced by three general circulation models

    NARCIS (Netherlands)

    Wanders, N.; Van Lanen, H. A J

    2015-01-01

    Hydrological drought characteristics (drought in groundwater and streamflow) likely will change in the 21st century as a result of climate change. The magnitude and directionality of these changes and their dependency on climatology and catchment characteristics, however, is uncertain. In this study

  10. Future discharge drought across climate regions around the world modelled with a synthetic hydrological modelling approach forced by three general circulation models

    NARCIS (Netherlands)

    Wanders, N.; Lanen, Van H.A.J.

    2015-01-01

    Hydrological drought characteristics (drought in groundwater and streamflow) likely will change in the 21st century as a result of climate change. The magnitude and directionality of these changes and their dependency on climatology and catchment characteristics, however, is uncertain. In this st

  11. The Impact of Elevated CO2 on Plant Production Responses to Drought: A Model-Data Comparison at Four US FACE Sites.

    Science.gov (United States)

    Walker, A. P.; De Kauwe, M. G.; Fenstermaker, L.; Medlyn, B. E.; Morgan, J. A.; Oren, R.; Zaehle, S.; Norby, R. J.

    2014-12-01

    Plants respond to increased atmospheric CO[2] (eCO2) by reducing stomatal apatures which increases plant water use efficiency. In some environments, increased WUE allows for water savings and can prolong the onset of drought effects on plants.Ecosystem observations from four long-term free air CO[2] enrichment (FACE) experiments—the evergreen needleleaf Duke Forest FACE experiment (NC), the deciduous broadleaf Oak Ridge FACE experiment (TN), the prairie heating and FACE experiment (WY), and the Nevada desert FACE experiment—were used to evaluate the assumptions of a suite of terrestrial ecosystem models.All sites suffered from a drought that affected annual net primary production (NPP) in at least one year. In all cases the NPP response to drought was affected by eCO2, however the relative response was both greater and smaller under eCO2 compared with ambient CO[2] conditions depending on the climate of the site in question. Model assumptions that were important in determining the eCO2 by drought interaction on plant productivity were the soil water content at which soil water becomes limiting to plants; whether soil water limitation affects stomatal conductance, photosynthetic parameters, or both; and the shape of the soil water limitation curve.

  12. Fighting Against Drought

    Institute of Scientific and Technical Information of China (English)

    YIN PUMIN

    2010-01-01

    @@ The severe drought in southwest China continues and has worsened shortages of drinking water,as recent rainfall in these areas has been far from adequate,said China's drought relief authorities on April 8. The drought situation is looking quite grave,said Chen Lei,Deputy Director of the Office of State Flood Control and Drought Relief Headquarters(SFDH).

  13. FORECASTING RESIDENTIAL ELECTRICITY CONSUMPTION IN BRAZIL: APPLICATION OF THE ARX MODEL

    OpenAIRE

    Joao Bosco de Castro; Alessandra de Ávila Montini

    2010-01-01

    This work aims to propose the application of the ARX model to forecast residential electricity consumption in Brazil. Such estimates are critical for decision making in the energy sector,  from a technical, economic and environmentally sustainable standpoint. The demand for electricity follows a multiplicative model based on economic theory and involves four explanatory variables: the cost of residential electricity, the actual average income, the inflation of domestic utilities and the elect...

  14. Management Options During the 2011-2012 Drought on the Apalachicola River: A Systems Dynamic Model Evaluation.

    Science.gov (United States)

    Leitman, S; Pine, W E; Kiker, G

    2016-08-01

    The Apalachicola-Chattahoochee-Flint River basin (ACF) is a large watershed in the southeastern United States. In 2012, the basin experienced the second year of a severe drought and the third multi-year drought in the last 15 years. During severe droughts, low reservoir and river levels can cause economic and ecological impacts to the reservoir, river, and estuarine ecosystems. During drought, augmenting Apalachicola River discharge through upstream reservoir releases and demand management are intuitive and often-suggested solutions to minimizing downstream effects. We assessed whether the existing reservoir system could be operated to minimize drought impacts on downstream water users and ecosystems through flow augmentation. Our analysis finds that in extreme drought such as observed during 2012, increases in water releases from reservoir storage are insufficient to even increase Apalachicola River discharge to levels observed in the 2007 drought. This suggests that there is simply not enough water available in managed storage to offset extreme drought events. Because drought frequency and intensity is predicted to increase under a variety of climate forecasts, our results demonstrate the need for a critical assessment of how water managers will meet increasing water demands in the ACF. Key uncertainties that should be addressed include (1) identifying the factors that led to extremely low Flint River discharge in 2012, and (2) determining how water "saved" via demand management is allocated to storage or passed to downstream ecosystem needs as part of the ongoing revisions to the ACF Water Control Manual by the US Army Corps of Engineers. PMID:27272165

  15. Model or Myopia? Exploiting Water Markets to Address Population and Drought Risks in a Changing World

    Science.gov (United States)

    Reed, P. M.

    2012-12-01

    Climate change, population demands, and evolving land-use represent strong risks to the sustainable development and stability of world-wide urban water supplies. There is a growing consensus that non-structural supply management instruments such as water markets have significant potential to reduce the risks and vulnerabilities in complex urban water systems. This paper asks a common question, what are the tradeoffs for a city using water market supply instruments?. This question emerges quickly in policy and management, but its answer is deceptively difficult to attain using traditional planning tools and management frameworks. This research demonstrates new frameworks that facilitate rapid evaluation of hypotheses on the reliability, resiliency, adaptability, and cost-effectiveness of urban water supply systems. This study considers a broader exploration of the issues of "nonstationarity" and "uncertainty" in urban water planning. As we invest in new information and prediction frameworks for the coupled human-natural systems that define our water, our problem definitions (i.e., objectives, constraints, preferences, and hypotheses) themselves evolve. From a formal mathematical perspective, this means that our management problems are structurally uncertain and nonstationary (i.e., the definition of optimality changes across regions, times, and stakeholders). This uncertainty and nonstationarity in our problem definitions needs to be more explicitly acknowledged in adaptive management and integrated water resources management. This study demonstrates the potential benefits of exploring these issues in the context of a city in the Lower Rio Grande Valley (LRGV) of Texas, USA determining how to use its regional water market to manage population and drought risks.

  16. Development of a model of rain water catchment for the semiarid from Brazil

    Directory of Open Access Journals (Sweden)

    Vera Lúcia Antunes de Lima

    2009-03-01

    Full Text Available The systems capture of rainwater for human consumption through roofs and its storage tanks is a growing practice, especially in regions devoid of sanitation, as much of the Semi-Arid Brazil. Aiming to contribute in improving the performance of systems of collection of rainwater, to ensure an uninterrupted supply, even during the most severe droughts, this work aimed at developing alternative roofing central to rural households, adopting appropriate technology to the population of the Semi-arid Brazilian considering economic aspects, functional and aesthetic-formal. The work started from information obtained from a field research, conducted in the rural community of Paus Brancos, county of Campina Grande, PB, between the years 2002 and 2003. After that were developing them and evaluated prototypes of rails. Although 80% of households surveyed have a system of water abstraction composed of a tank, rails and receiving system of driving, only 16% hold a sufficient volume to supply all year. The pipeline that has a better performance in collecting and carrying water was one that showed a J-shaped profile, and is characterized in one piece with good rigidity and good finishing.

  17. A comparison of corporate distress prediction models in Brazil: hybrid neural networks, logit models and discriminant analysis

    Directory of Open Access Journals (Sweden)

    Juliana Yim

    2005-01-01

    Full Text Available This paper looks at the ability of a relatively new technique, hybrid ANN's, to predict corporate distress in Brazil. These models are compared with traditional statistical techniques and conventional ANN models. The results suggest that hybrid neural networks outperform all other models in predicting firms in financial distress one year prior to the event. This suggests that for researchers, policymakers and others interested in early warning systems, hybrid networks may be a useful tool for predicting firm failure.

  18. Development of an Assimilation Scheme for the Estimation of Drought-Induced Yield Losses Based on Multi-Source Remote Sensing and the AcquaCrop Model

    Science.gov (United States)

    Silvestro, Paolo Cosmo; Casa, Raffaele; Pignatti, Stefano; Castaldi, Fabio; Yang, Hao; Yang, Guijun

    2014-11-01

    In the context of the Dragon-3 Farmland Drought project, our research deals with the development of methods for the assimilation of biophysical variables, estimated from multi-source remote sensing, into the AquaCrop model, in order to estimate the yield losses due to drought both at the farm and at the regional scale. The first part of this project was employed to refine a methodology to obtain maps of leaf area index (LAI), canopy cover (CC), fraction of adsorbed photosynthetically active radiation (FAPAR) and chlorophyll (Cab) from satellite optical data, using algorithms based on the training of artificial neural networks (ANN) on PROSAIL model simulations. In the second part, retrieved values of CC were assimilated into the AquaCrop model using the assimilation method of the Ensemble Kalman Filter to estimate grain wheat yield at the field scale.

  19. A model for estimation of potential generation of waste electrical and electronic equipment in Brazil

    International Nuclear Information System (INIS)

    Highlights: ► Literature of WEEE generation in developing countries is reviewed. ► We analyse existing estimates of WEEE generation for Brazil. ► We present a model for WEEE generation estimate. ► WEEE generation of 3.77 kg/capita year for 2008 is estimated. ► Use of constant lifetime should be avoided for non-mature market products. - Abstract: Sales of electrical and electronic equipment are increasing dramatically in developing countries. Usually, there are no reliable data about quantities of the waste generated. A new law for solid waste management was enacted in Brazil in 2010, and the infrastructure to treat this waste must be planned, considering the volumes of the different types of electrical and electronic equipment generated. This paper reviews the literature regarding estimation of waste electrical and electronic equipment (WEEE), focusing on developing countries, particularly in Latin America. It briefly describes the current WEEE system in Brazil and presents an updated estimate of generation of WEEE. Considering the limited available data in Brazil, a model for WEEE generation estimation is proposed in which different methods are used for mature and non-mature market products. The results showed that the most important variable is the equipment lifetime, which requires a thorough understanding of consumer behavior to estimate. Since Brazil is a rapidly expanding market, the “boom” in waste generation is still to come. In the near future, better data will provide more reliable estimation of waste generation and a clearer interpretation of the lifetime variable throughout the years.

  20. Seasonal Drought Prediction in India

    Science.gov (United States)

    Shah, R.; Mishra, V.

    2015-12-01

    Drought is among the most costly natural disasters in India. Seasonal prediction of drought can assist planners to manage agriculture and water resources. Such information can be valuable for a country like India where 60% of agriculture is rain-fed. Here we evaluate precipitation and temperature forecast from the NCEP's CFSV2 for seasonal drought prediction in India. We demonstrate the utility of the seasonal prediction of precipitation and temperature for drought forecast at 1-2 months lead time at a high spatial resolution. Precipitation from CFSv2 showed moderate correlations with observed up to two months lead. For one month lead, we found a significant correlation between CFSv2 and observed precipitation during winter season. Air temperature from the CFSv2 showed a good correlation with observed temperature during the winter. We forced the Variable Infiltration Capacity (VIC) model with the CFSv2 forecast of precipitation and air temperature to generate forecast of hydrologic variables such as soil moisture and total runoff. We find that errors of the prediction reduce for the two month lead time in the majority of the study domain except the northern India. Skills of Initial Hydrologic Conditions combined with moderate skills of forcings based on the CFSv2 showed ability of drought prediction in India. The developed system was able to successfully predict observed top layer soil moisture and observed drought based on satellite remote sensing in India.

  1. A model for estimation of potential generation of waste electrical and electronic equipment in Brazil.

    Science.gov (United States)

    Araújo, Marcelo Guimarães; Magrini, Alessandra; Mahler, Cláudio Fernando; Bilitewski, Bernd

    2012-02-01

    Sales of electrical and electronic equipment are increasing dramatically in developing countries. Usually, there are no reliable data about quantities of the waste generated. A new law for solid waste management was enacted in Brazil in 2010, and the infrastructure to treat this waste must be planned, considering the volumes of the different types of electrical and electronic equipment generated. This paper reviews the literature regarding estimation of waste electrical and electronic equipment (WEEE), focusing on developing countries, particularly in Latin America. It briefly describes the current WEEE system in Brazil and presents an updated estimate of generation of WEEE. Considering the limited available data in Brazil, a model for WEEE generation estimation is proposed in which different methods are used for mature and non-mature market products. The results showed that the most important variable is the equipment lifetime, which requires a thorough understanding of consumer behavior to estimate. Since Brazil is a rapidly expanding market, the "boom" in waste generation is still to come. In the near future, better data will provide more reliable estimation of waste generation and a clearer interpretation of the lifetime variable throughout the years.

  2. RESPONSE OF REGIONAL AIR QUALITY TO SEVERE DROUGHT

    Science.gov (United States)

    Severe droughts are a recurring phenomenon throughout the southwestern United States, and most climate models suggest that these droughts will become more severe as climate changes in response to increased concentrations of greenhouse gases and other radiative forcing spec...

  3. Drought and climatic change impact on streamflow in small watersheds.

    Science.gov (United States)

    Tigkas, Dimitris; Vangelis, Harris; Tsakiris, George

    2012-12-01

    The paper presents a comprehensive, thought simple, methodology, for forecasting the annual hydrological drought, based on meteorological drought indications available early during the hydrological year. The meteorological drought of 3, 6 and 9 months is estimated using the reconnaissance drought index (RDI), whereas the annual hydrological drought is represented by the streamflow drought index (SDI). Regression equations are derived between RDI and SDI, forecasting the level of hydrological drought for the entire year in real time. Further, using a wide range of scenarios representing possible climatic changes and drought events of varying severity, nomographs are devised for estimating the annual streamflow change. The Medbasin rainfall-runoff model is used to link meteorological data to streamflow. The later approach can be useful for developing preparedness plans to combat the consequences of drought and climate change. As a case study, the area of N. Peloponnese (Greece) was selected, incorporating several small river basins.

  4. Drought and climatic change impact on streamflow in small watersheds.

    Science.gov (United States)

    Tigkas, Dimitris; Vangelis, Harris; Tsakiris, George

    2012-12-01

    The paper presents a comprehensive, thought simple, methodology, for forecasting the annual hydrological drought, based on meteorological drought indications available early during the hydrological year. The meteorological drought of 3, 6 and 9 months is estimated using the reconnaissance drought index (RDI), whereas the annual hydrological drought is represented by the streamflow drought index (SDI). Regression equations are derived between RDI and SDI, forecasting the level of hydrological drought for the entire year in real time. Further, using a wide range of scenarios representing possible climatic changes and drought events of varying severity, nomographs are devised for estimating the annual streamflow change. The Medbasin rainfall-runoff model is used to link meteorological data to streamflow. The later approach can be useful for developing preparedness plans to combat the consequences of drought and climate change. As a case study, the area of N. Peloponnese (Greece) was selected, incorporating several small river basins. PMID:22963988

  5. Applying the Triangle Method for the parameterization of irrigated areas as input for spatially distributed hydrological modeling - Assessing future drought risk in the Gaza Strip (Palestine).

    Science.gov (United States)

    Gampe, David; Ludwig, Ralf; Qahman, Khalid; Afifi, Samir

    2016-02-01

    In the Mediterranean region, particularly in the Gaza strip, an increased risk of drought is among the major concerns related to climate change. The impacts of climate change on water availability, drought risk and food security can be assessed by means of hydro-climatological modeling. However, the region is prone to severe observation data scarcity, which limits the potential for robust model parameterization, calibration and validation. In this study, the physically based, spatially distributed hydrological model WaSiM is parameterized and evaluated using satellite imagery to assess hydrological quantities. The Triangle Method estimates actual evapotranspiration (ETR) through the Normalized Difference Vegetation Index (NDVI) and land surface temperature (LST) provided by Landsat TM imagery. So-derived spatially distributed evapotranspiration is then used in two ways: first a subset of the imagery is used to parameterize the irrigation module of WaSiM and second, withheld scenes are applied to evaluate the performance of the hydrological model in the data scarce study area. The results show acceptable overall correlation with the validation scenes (r=0.53) and an improvement over the usual irrigation parameterization scheme using land use information exclusively. This model setup is then applied for future drought risk assessment in the Gaza Strip using a small ensemble of four regional climate projections for the period 2041-2070. Hydrological modeling reveals an increased risk of drought, assessed with an evapotranspiration index, compared to the reference period 1971-2000. Current irrigation procedures cannot maintain the agricultural productivity under future conditions without adaptation.

  6. The 2010 Russian Drought Impact on Satellite Measurements of Solar-Induced Chlorophyll Fluorescence: Insights from Modeling and Comparisons with the Normalized Differential Vegetation Index (NDVI)

    Science.gov (United States)

    Yoshida, Y.; Joiner, J.; Tucker, C.; Berry, J.; Lee, J. -E.; Walker, G.; Reichle, R.; Koster, R.; Lyapustin, A.; Wang, Y.

    2015-01-01

    We examine satellite-based measurements of chlorophyll solar-induced fluorescence (SIF) over the region impacted by the Russian drought and heat wave of 2010. Like the popular Normalized Difference Vegetation Index (NDVI) that has been used for decades to measure photosynthetic capacity, SIF measurements are sensitive to the fraction of absorbed photosynthetically-active radiation (fPAR). However, in addition, SIF is sensitive to the fluorescence yield that is related to the photosynthetic yield. Both SIF and NDVI from satellite data show drought-related declines early in the growing season in 2010 as compared to other years between 2007 and 2013 for areas dominated by crops and grasslands. This suggests an early manifestation of the dry conditions on fPAR. We also simulated SIF using a global land surface model driven by observation-based meteorological fields. The model provides a reasonable simulation of the drought and heat impacts on SIF in terms of the timing and spatial extents of anomalies, but there are some differences between modeled and observed SIF. The model may potentially be improved through data assimilation or parameter estimation using satellite observations of SIF (as well as NDVI). The model simulations also offer the opportunity to examine separately the different components of the SIF signal and relationships with Gross Primary Productivity (GPP).

  7. Plant Survival and Mortality during Drought Can be Mediated by Co-occurring Species' Physiological and Morphological Traits: Results from a Model

    Science.gov (United States)

    Tai, X.; Mackay, D. S.

    2015-12-01

    Interactions among co-occurring species are mediated by plant physiology, morphology and environment. Without proper mechanisms to account for these factors, it remains difficult to predict plant mortality/survival under changing climate. A plant ecophysiological model, TREES, was extended to incorporate co-occurring species' belowground interaction for water. We used it to examine the interaction between two commonly co-occurring species during drought experiment, pine (Pinus edulis) and juniper (Juniperus monosperma), with contrasting physiological traits (vulnerability to cavitation and leaf water potential regulation). TREES was parameterized and validated using field-measured plant physiological traits. The root architecture (depth, profile, and root area to leaf area ratio) of juniper was adjusted to see how root morphology could affect the survival/mortality of its neighboring pine under both ambient and drought conditions. Drought suppressed plant water and carbon uptake, as well increased the average percentage loss of conductivity (PLC). Pine had 59% reduction in water uptake, 48% reduction in carbon uptake, and 38% increase in PLC, while juniper had 56% reduction in water uptake, 50% reduction in carbon and 29% increase in PLC, suggesting different vulnerability to drought as mediated by plant physiological traits. Variations in juniper root architecture further mediated drought stress on pine, from negative to positive. Different juniper root architecture caused variations in response of pine over drought (water uptake reduction ranged 0% ~63%, carbon uptake reduction ranged 0% ~ 70%, and PLC increase ranged 2% ~ 91%). Deeper or more uniformly distributed roots of juniper could effectively mitigate stress experienced by pine. In addition, the total water and carbon uptake tended to increase as the ratio of root area to leaf area increased while PLC showed non-monotonic response, suggesting the potential trade-off between maximizing resource uptake and

  8. Índice padronizado de precipitação aplicado às condições de seca no Estado do Espírito Santo Standardized precipitation index applied to drought conditions of the State of Espírito Santo, Brazil

    Directory of Open Access Journals (Sweden)

    Gabriel C. Blain

    2010-10-01

    Full Text Available O Índice Padronizado de Precipitação (SPI é um dos métodos mais utilizados para quantificação da seca. A fim de verificar a possibilidade de utilização do SPI no monitoramento das deficiências e excessos de precipitação na escala mensal, no Estado do Espírito Santo objetivou-se, neste trabalho, verificar o ajuste das séries temporais dessa variável meteorológica à distribuição gama em cinco localidades do Estado. Por meio dos testes de aderência Kolmogorov-Smirnov e qui-quadrado, as séries mensais de precipitação pluvial das localidades sob análise podem ser consideradas oriundas de uma população com distribuição gama incompleta, permitindo o uso do SPI no monitoramento das condições de seca meteorológica. Através de análises de autocorrelação e correlação-cruzada, observou-se que a principal característica das séries do SPI é sua grande variabilidade espaço-temporal, a qual indica que em uma mesma região meses extremamente secos podem ser precedidos e/ou seguidos de meses úmidos ou normais, e que distintos casos de seca podem ocorrer de forma aleatória, entre as localidades e em um mesmo período.The Standardized Precipitation Index (SPI is one of the most widely used methods for quantification of drought conditions. In order to apply the SPI model to the climate conditions of the State of Espírito Santo, Brazil, the study evaluated the adjustment of the monthly rainfall time series to the gamma distribution in five regions of this State. Using the Kolmogorov-Smirnov test and the Chi-Square test, it was possible to verify that the monthly rainfall time series, used in this study, can be fitted to the gamma distribution. On this sense, the SPI model can be applied for monitoring the meteorological drought conditions in the State of Espírito Santo. Using the autocorrelation function and the cross-correlation function, it was possible to verify that the main characteristic of the monthly SPI series is

  9. MODELLING THIRTY FIVE YEARS OF COFFEE PRICES IN BRAZIL, GUATEMALA AND INDIA

    OpenAIRE

    Sushil Mohan; Bill Russell

    2008-01-01

    Over the past thirty five years coffee markets have been subject to market controls and regulations culminating in the liberalisation of coffee markets in the early 1990s. This paper models the relationship between the producers’ and world prices of coffee in Brazil, Guatemala and India allowing for the effects of changes in market structures. We find that liberalisation has benefited producers substantially in terms of higher real coffee prices and a higher share of the world price of coffee.

  10. A taphonomic model for the Mesosauride assemblage of the Irati Formation (Paraná Basin, Brazil)

    OpenAIRE

    Soares, M B

    2003-01-01

    The Irati Formation (Permian, Paraná Basin, Brazil) is made up of a succession of black bituminous and nonbituminous shales and mudstones with interbedded carbonate layers, which record deposition in marine environments. Mesosaur remains are abundant at several sites in this formation, where they occur preserved in centimetre- thick beds and displaying various degrees of skeletal disarticulation. This paper seeks to establish a model to explain the processes that generated the mesosaurian tap...

  11. Modified Palmer Drought Severity Index Based on Distributed Hydrological Simulation

    Directory of Open Access Journals (Sweden)

    Denghua Yan

    2013-01-01

    Full Text Available Drought monitoring at large scale is essential for fighting against drought. Aiming at the limitation of acquiring long-time serial soil moisture and actual evapotranspiration for Palmer drought severity index (PDSI, the paper modified the PDSI based on distributed hydrological model on subbasin level in Luanhe river basin, North China. The water balance was simulated using the Soil and Water Assessment Tool (SWAT. Calibration and validation results showed good agreement between simulated and measured discharges, and the SWAT model can be used to predict hydrological processes in the study area. Then the simulation results of main hydrologic components were used to establish PDSI. The verification of the drought indices showed that the modified PDSI based on SWAT model and Palmer drought severity index could better describe the characteristics of regional drought evolution in the Luanhe river basin. High drought frequency areas were mainly distributed in the grassland regions of upstream located in the eastern part of Inner Mongolia plateau, and the drought area had a significant upward trend form 1973 to 2010. Compared with the traditional Palmer drought severity index, the modified PDSI could reflect the spatial heterogeneity of regional drought and improve the physical mechanism of PDSI. The drought monitoring method can provide technical support for comprehensive understanding of drought and effective preventing and relieving of drought disasters.

  12. Modelling the ecological niche of hookworm in Brazil based on climate

    Directory of Open Access Journals (Sweden)

    Ntombi B. Mudenda

    2012-09-01

    Full Text Available The distribution of hookworm in schistosomiasis-endemic areas in Brazil was mapped based on climate suitability. Known biological requirements of hookworm were fitted to data in a monthly long-term normal climate grid (18 x 18 km using geographical information systems. Hookworm risk models were produced using the growing degree day (GDD water budget (WB concept. A moisture-adjusted model (MA-GDD was developed based on accumulation of monthly temperatures above a base temperature of 15 °C (below which there is no lifecycle progression of Necator americanus conditional on concurrent monthly values (rain/potential, evapotranspiration of over 0.4. A second model, designated the gradient index, was calculated based on the monthly accumulation of the product of GDD and monthly WB values (GDD x WB. Both parameters had a significant positive correlation to hookworm prevalence. In the northeastern part of Brazil (the Caatinga, low hookworm prevalence was due to low soil moisture content, while the low prevalence in southern Brazil was related to low mean monthly temperatures. Both environmental temperature and soil moisture content were found to be important parameters for predicting the prevalence of N. americanus.

  13. Citrus plants: a model system for unlocking the secrets of NO and ROS-inspired priming against salinity and drought

    Directory of Open Access Journals (Sweden)

    Athanassios eMolassiotis

    2016-02-01

    Full Text Available Plants treated with chemical compounds can develop an enhanced capacity to resist long after treatment to (abiotic stress, a phenomenon known as priming. Evidence suggests that reactive oxygen species (ROS and reactive nitrogen species (RNS coordinately regulate plant stress responses to adverse environmental conditions; however the mechanisms underlying this function remain unknown. Based on the observation that pre-exposure of citrus (Citrus aurantium L. roots to the NO donor sodium nitroprusside (SNP or to H2O2 prior to NaCl application can induce acclimation against subsequent stress we characterized the changes occurred in primed citrus tissues using several approaches. Herein, using this experimental model system, we provide an overview of our current knowledge of the possible mechanisms associated with NO and H2O2 priming to abiotic stresses, most remarkably on salt and drought. The data and ideas presented here introduce six aspects of priming behaviour in citrus under abiotic stress that provide knowledge necessary to exploit priming syndrome in the context of sustainable agriculture.

  14. Citrus Plants: A Model System for Unlocking the Secrets of NO and ROS-Inspired Priming Against Salinity and Drought.

    Science.gov (United States)

    Molassiotis, Athanassios; Job, Dominique; Ziogas, Vasileios; Tanou, Georgia

    2016-01-01

    Plants treated with chemical compounds can develop an enhanced capacity to resist long after being subjected to (a)biotic stress, a phenomenon known as priming. Evidence suggests that reactive oxygen species (ROS) and reactive nitrogen species (RNS) coordinately regulate plant stress responses to adverse environmental conditions; however, the mechanisms underlying this function remain unknown. Based on the observation that pre-exposure of citrus (Citrus aurantium L.) roots to the NO donor sodium nitroprusside (SNP) or to H2O2 prior to NaCl application can induce acclimation against subsequent stress we characterized the changes occurring in primed citrus tissues using several approaches. Herein, using this experimental model system, we provide an overview of our current knowledge of the possible mechanisms associated with NO and H2O2 priming to abiotic stresses, particularly concerning salinity and drought. The data and ideas presented here introduce six aspects of priming behavior in citrus under abiotic stress that provide knowledge necessary to exploit priming syndrome in the context of sustainable agriculture.

  15. MicroRNAs and drought responses in sugarcane

    OpenAIRE

    Gentile, Agustina; Dias, Lara I.; Mattos, Raphael S.; Ferreira, Thaís H.; Menossi, Marcelo

    2015-01-01

    There is a growing demand for renewable energy, and sugarcane is a promising bioenergy crop. In Brazil, the largest sugarcane producer in the world, sugarcane plantations are expanding into areas where severe droughts are common. Recent evidence has highlighted the role of miRNAs in regulating drought responses in several species, including sugarcane. This review summarizes the data from miRNA expression profiles observed in a wide array of experimental conditions using different sugarcane cu...

  16. MicroRNAs and Drought Responses in Sugarcane

    OpenAIRE

    Marcelo Menossi Menossi; Agustina eGentile; Thaís Helena Ferreira; Raphael de Souza Mattos; Lara Isys Dias

    2015-01-01

    There is a growing demand for renewable energy, and sugarcane is a promising bioenergy crop. In Brazil, the largest sugarcane producer in the world, sugarcane plantations are expanding into areas where severe droughts are common. Recent evidence has highlighted the role of miRNAs in regulating drought responses in several species, including sugarcane. This review summarizes the data from miRNA expression profiles observed in a wide array of experimental conditions using different sugarcane cu...

  17. Estimating drought risk across Europe from reported drought impacts, hazard indicators and vulnerability factors

    Science.gov (United States)

    Blauhut, V.; Stahl, K.; Stagge, J. H.; Tallaksen, L. M.; De Stefano, L.; Vogt, J.

    2015-12-01

    Drought is one of the most costly natural hazards in Europe. Due to its complexity, drought risk, the combination of the natural hazard and societal vulnerability, is difficult to define and challenging to detect and predict, as the impacts of drought are very diverse, covering the breadth of socioeconomic and environmental systems. Pan-European maps of drought risk could inform the elaboration of guidelines and policies to address its documented severity and impact across borders. This work (1) tests the capability of commonly applied hazard indicators and vulnerability factors to predict annual drought impact occurrence for different sectors and macro regions in Europe and (2) combines information on past drought impacts, drought hazard indicators, and vulnerability factors into estimates of drought risk at the pan-European scale. This "hybrid approach" bridges the gap between traditional vulnerability assessment and probabilistic impact forecast in a statistical modelling framework. Multivariable logistic regression was applied to predict the likelihood of impact occurrence on an annual basis for particular impact categories and European macro regions. The results indicate sector- and macro region specific sensitivities of hazard indicators, with the Standardised Precipitation Evapotranspiration Index for a twelve month aggregation period (SPEI-12) as the overall best hazard predictor. Vulnerability factors have only limited ability to predict drought impacts as single predictor, with information about landuse and water resources as best vulnerability-based predictors. (3) The application of the "hybrid approach" revealed strong regional (NUTS combo level) and sector specific differences in drought risk across Europe. The majority of best predictor combinations rely on a combination of SPEI for shorter and longer aggregation periods, and a combination of information on landuse and water resources. The added value of integrating regional vulnerability information

  18. Global integrated drought monitoring and prediction system.

    Science.gov (United States)

    Hao, Zengchao; AghaKouchak, Amir; Nakhjiri, Navid; Farahmand, Alireza

    2014-01-01

    Drought is by far the most costly natural disaster that can lead to widespread impacts, including water and food crises. Here we present data sets available from the Global Integrated Drought Monitoring and Prediction System (GIDMaPS), which provides drought information based on multiple drought indicators. The system provides meteorological and agricultural drought information based on multiple satellite-, and model-based precipitation and soil moisture data sets. GIDMaPS includes a near real-time monitoring component and a seasonal probabilistic prediction module. The data sets include historical drought severity data from the monitoring component, and probabilistic seasonal forecasts from the prediction module. The probabilistic forecasts provide essential information for early warning, taking preventive measures, and planning mitigation strategies. GIDMaPS data sets are a significant extension to current capabilities and data sets for global drought assessment and early warning. The presented data sets would be instrumental in reducing drought impacts especially in developing countries. Our results indicate that GIDMaPS data sets reliably captured several major droughts from across the globe. PMID:25977759

  19. Not all droughts are created equal: The impacts of interannual drought pattern and magnitude on grassland carbon cycling

    Science.gov (United States)

    Hoover, David L; Rogers, Brendan M.

    2016-01-01

    Climate extremes, such as drought, may have immediate and potentially prolonged effects on carbon cycling. Grasslands store approximately one-third of all terrestrial carbon and may become carbon sources during droughts. However, the magnitude and duration of drought-induced disruptions to the carbon cycle, as well as the mechanisms responsible, remain poorly understood. Over the next century, global climate models predict an increase in two types of drought: chronic but subtle ‘press-droughts’, and shorter term but extreme ‘pulse-droughts’. Much of our current understanding of the ecological impacts of drought comes from experimental rainfall manipulations. These studies have been highly valuable, but are often short term and rarely quantify carbon feedbacks. To address this knowledge gap, we used the Community Land Model 4.0 to examine the individual and interactive effects of pulse- and press-droughts on carbon cycling in a mesic grassland of the US Great Plains. A series of modeling experiments were imposed by varying drought magnitude (precipitation amount) and interannual pattern (press- vs. pulse-droughts) to examine the effects on carbon storage and cycling at annual to century timescales. We present three main findings. First, a single-year pulse-drought had immediate and prolonged effects on carbon storage due to differential sensitivities of ecosystem respiration and gross primary production. Second, short-term pulse-droughts caused greater carbon loss than chronic press-droughts when total precipitation reductions over a 20-year period were equivalent. Third, combining pulse- and press-droughts had intermediate effects on carbon loss compared to the independent drought types, except at high drought levels. Overall, these results suggest that interannual drought pattern may be as important for carbon dynamics as drought magnitude and that extreme droughts may have long-lasting carbon feedbacks in grassland ecosystems.

  20. Advancing Drought Understanding, Monitoring and Prediction

    Science.gov (United States)

    Mariotti, Annarita; Schubert, Siegfried D.; Mo, Kingtse; Peters-Lidard, Christa; Wood, Andy; Pulwarty, Roger; Huang, Jin; Barrie, Dan

    2013-01-01

    Having the capacity to monitor droughts in near-real time and providing accurate drought prediction from weeks to seasons in advance can greatly reduce the severity of social and economic damage caused by drought, a leading natural hazard for North America. The congressional mandate to establish the National Integrated Drought Information System (NIDIS; Public Law 109-430) in 2006 was a major impulse to develop, integrate, and provide drought information to meet the challenges posed by this hazard. Significant progress has been made on many fronts. On the research front, efforts by the broad scientific community have resulted in improved understanding of North American droughts and improved monitoring and forecasting tools. We now have a better understanding of the droughts of the twentieth century including the 1930s "Dust Bowl"; we have developed a broader array of tools and datasets that enhance the official North American Drought Monitor based on different methodologies such as state-of-the-art land surface modeling (e.g., the North American Land Data Assimilation System) and remote sensing (e.g., the evaporative stress index) to better characterize the occurrence and severity of drought in its multiple manifestations. In addition, we have new tools for drought prediction [including the new National Centers for Environmental Prediction (NCEP) Climate Forecast System, version 2, for operational prediction and an experimental National Multimodel Ensemble] and have explored diverse methodologies including ensemble hydrologic prediction approaches. Broad NIDIS-inspired progress is influencing the development of a Global Drought Information System (GDIS) under the auspices of the World Climate Research Program. Despite these advances, current drought monitoring and forecasting capabilities still fall short of users' needs, especially the need for skillful and reliable drought forecasts at regional and local scales. To tackle this outstanding challenging problem

  1. Sugarcane Water Sustainability Assessment Through the Indicators Extracted from Spatial Models: Case Study of Sugarcane Expansion Hotspots in Brazil

    Science.gov (United States)

    Ferraz, R. P.; Simoes, M.; Dubreuil, V.

    2012-12-01

    The CanaSat project data from INPE (2010) has evidenced the trend of sugarcane expansion into savanna areas in the Midwest region of Brazil that has a great potential for the sugarcane development, in terms of topography and suitable soils, according to Sugarcane Agroecological Zoning (EMBRAPA, 2009). However, in this region the climatic water availability has limitations, once the climate is marked by drought season with a strong water deficiency due to reduction of rainfall (SILVA et al. 2008). There may be serious risks to the sugarcane culture conducted in dryland crop system without any support from additional irrigation. Silva et al. (2008) state that, for the expansion of sugarcane cultivation in the Cerrado region will be necessary supplemental irrigation with 80 to 120 mm of water applied after cutting or planting. In the Brazilian Midwest the sugarcane agroindustry expansion is technically viable, but for the sustainable development of this activity it is necessary an adequate planning based on knowledge about water demand and availability. The aim of this study was to conduct an assessment of the potential water sustainability for the sugarcane cultivation in four microregions in Goiás State, Brazil, through the use of indicators proposed in Indicators System of Sugarcane Water Sustainability Assessment (Ferraz, 2012), that was thought to subsidize the public policies proposals and sectoral planning in strategic level by means of indicators that enable to perform diagnostic and prognostic analysis. These indicators are direct and relevant indexes obtained from data extracted through geoprocessing techniques from integration of many spatial models. The used indicators were: (i) Three indexes expressing the land favorability for sugarcane development conducted in dryland or irrigation system through the establishment of the ratio between the sugarcane suitable area for each different system and the total area of territorial unit of analysis (micro

  2. Upscaling drought information from the catchment scale to the global scale: how seasonality in climate influences drought characteristics

    Science.gov (United States)

    Van Loon, Anne; Tijdeman, Erik; Wanders, Niko; Van Lanen, Henny; Teuling, Adriaan; Uijlenhoet, Remko

    2013-04-01

    The upscaling of the understanding of hydrological processes from the catchment scale to the global scale is not straightforward, especially not for hydrological extremes as floods and droughts. For large-scale water resources management, information on the development and persistence of soil moisture and hydrological droughts is crucial. The characteristics of these droughts (i.e. duration and severity) vary around the world and are dependent on climate and catchment properties. In this study, we investigated climate controls on drought propagation (i.e. the translation of meteorological conditions to a soil moisture drought and/or hydrological drought) by isolating forcing effects from effects of catchment properties. We used a conceptual hydrological model, forced by the WATCH forcing data, that was run for 1271 grid cells distributed over the global climate zones. The precipitation that was used as input, and soil moisture storage and subsurface discharge that were outcomes of the model, were then analysed with a well-known drought identification method (variable threshold level method). Drought characteristics duration and standardised deficit (deficit below the smoothed monthly-varying threshold, divided by the mean of the variable for that grid cell) were determined for each drought event. These drought characteristics were clustered per subclimate type and combined into bivariate probability density fields. The shape and orientation of these density fields provide information on the propagation of drought in different climate zones. Drought propagation features that are apparent on the catchment scale, such as pooling (meteorological droughts are merged into a prolonged hydrological drought) and attenuation (the damping effect of stores on the drought signal), were reproduced in all climate zones. But also seasonal drought types that can have severe impacts on the catchment scale (e.g. rain-to-snow-season drought) leave a pronounced signal in the density

  3. How climate seasonality modifies drought duration and deficit

    NARCIS (Netherlands)

    van Loon, A.F.; Tijdeman, E.; Wanders, N.; Lanen, H.A.J.; Teuling, A.J.; Uijlenhoet, R.

    2014-01-01

    Drought propagation through the terrestrial hydrological cycle is associated with a change in drought characteristics (duration and deficit), moving from precipitation via soil moisture to discharge. Here we investigate climate controls on drought propagation with a modeling experiment in 1271 virtu

  4. Tests of species-specific models reveal the importance of drought in postglacial range shifts of a Mediterranean-climate tree: insights from integrative distributional, demographic and coalescent modelling and ABC model selection.

    Science.gov (United States)

    Bemmels, Jordan B; Title, Pascal O; Ortego, Joaquín; Knowles, L Lacey

    2016-10-01

    Past climate change has caused shifts in species distributions and undoubtedly impacted patterns of genetic variation, but the biological processes mediating responses to climate change, and their genetic signatures, are often poorly understood. We test six species-specific biologically informed hypotheses about such processes in canyon live oak (Quercus chrysolepis) from the California Floristic Province. These hypotheses encompass the potential roles of climatic niche, niche multidimensionality, physiological trade-offs in functional traits, and local-scale factors (microsites and local adaptation within ecoregions) in structuring genetic variation. Specifically, we use ecological niche models (ENMs) to construct temporally dynamic landscapes where the processes invoked by each hypothesis are reflected by differences in local habitat suitabilities. These landscapes are used to simulate expected patterns of genetic variation under each model and evaluate the fit of empirical data from 13 microsatellite loci genotyped in 226 individuals from across the species range. Using approximate Bayesian computation (ABC), we obtain very strong support for two statistically indistinguishable models: a trade-off model in which growth rate and drought tolerance drive habitat suitability and genetic structure, and a model based on the climatic niche estimated from a generic ENM, in which the variables found to make the most important contribution to the ENM have strong conceptual links to drought stress. The two most probable models for explaining the patterns of genetic variation thus share a common component, highlighting the potential importance of seasonal drought in driving historical range shifts in a temperate tree from a Mediterranean climate where summer drought is common.

  5. FORECASTING RESIDENTIAL ELECTRICITY CONSUMPTION IN BRAZIL: APPLICATION OF THE ARX MODEL

    Directory of Open Access Journals (Sweden)

    Joao Bosco de Castro

    2010-11-01

    Full Text Available This work aims to propose the application of the ARX model to forecast residential electricity consumption in Brazil. Such estimates are critical for decision making in the energy sector,  from a technical, economic and environmentally sustainable standpoint. The demand for electricity follows a multiplicative model based on economic theory and involves four explanatory variables: the cost of residential electricity, the actual average income, the inflation of domestic utilities and the electricity consumption. The coefficients of the electricity consumption equation  were determined using the ARX model, which considers the influence of exogenous variables to estimate the dependent variable and employs an autoregression process for residual modeling to improve the explanatory power. The resulting model has a determination coefficient of 95.4 percent and all estimated coefficients were significant at the 0.10 descriptive level. Residential electricity consumption estimates were also determined for January and February 2010 within the 95 percent confidence interval, which included the actual consumption figures observed. The proposed model has been shown to be useful for estimating residential electricity consumption  in Brazil. Key-words: Time series. Electricity consumption. ARX modeling

  6. A rate equation model of stomatal responses to vapour pressure deficit and drought

    Directory of Open Access Journals (Sweden)

    Shanahan ST

    2002-08-01

    Full Text Available Abstract Background Stomata respond to vapour pressure deficit (D – when D increases, stomata begin to close. Closure is the result of a decline in guard cell turgor, but the link between D and turgor is poorly understood. We describe a model for stomatal responses to increasing D based upon cellular water relations. The model also incorporates impacts of increasing levels of water stress upon stomatal responses to increasing D. Results The model successfully mimics the three phases of stomatal responses to D and also reproduces the impact of increasing plant water deficit upon stomatal responses to increasing D. As water stress developed, stomata regulated transpiration at ever decreasing values of D. Thus, stomatal sensitivity to D increased with increasing water stress. Predictions from the model concerning the impact of changes in cuticular transpiration upon stomatal responses to increasing D are shown to conform to experimental data. Sensitivity analyses of stomatal responses to various parameters of the model show that leaf thickness, the fraction of leaf volume that is air-space, and the fraction of mesophyll cell wall in contact with air have little impact upon behaviour of the model. In contrast, changes in cuticular conductance and membrane hydraulic conductivity have significant impacts upon model behaviour. Conclusion Cuticular transpiration is an important feature of stomatal responses to D and is the cause of the 3 phase response to D. Feed-forward behaviour of stomata does not explain stomatal responses to D as feedback, involving water loss from guard cells, can explain these responses.

  7. DroughtDB: an expert-curated compilation of plant drought stress genes and their homologs in nine species

    OpenAIRE

    Alter, Svenja; Bader, Kai C.; Spannagl, Manuel; Wang, Yu; Bauer, Eva; Schön, Chris-Carolin; Mayer, Klaus F. X.

    2015-01-01

    Plants are sessile and therefore exposed to a number of biotic and abiotic stresses. Drought is the major abiotic stress restricting plant growth worldwide. A number of genes involved in drought stress response have already been characterized, mainly in the model species Arabidopsis thaliana and Oryza sativa. However, with the aim to produce drought tolerant crop varieties, it is of importance to identify the respective orthologs for each species. We have developed DroughtDB, a manually curat...

  8. On the spatio-temporal analysis of hydrological droughts from global hydrological models

    NARCIS (Netherlands)

    Corzo Perez, G.; Huijgevoort, van M.H.J.; Voss, F.; Lanen, van H.A.J.

    2011-01-01

    The recent concerns for world-wide extreme events related to climate change have motivated the development of large scale models that simulate the global water cycle. In this context, analysis of hydrological extremes is important and requires the adaptation of identification methods used for river

  9. Survival benefits of antiretroviral therapy in Brazil: a model-based analysis

    Science.gov (United States)

    Luz, Paula M; Girouard, Michael P; Grinsztejn, Beatriz; Freedberg, Kenneth A; Veloso, Valdilea G; Losina, Elena; Struchiner, Claudio J; MacLean, Rachel L; Parker, Robert A; Paltiel, A David; Walensky, Rochelle P

    2016-01-01

    Objective In Brazil, universal provision of antiretroviral therapy (ART) has been guaranteed free of charge to eligible HIV-positive patients since December 1996. We sought to quantify the survival benefits of ART attributable to this programme. Methods We used a previously published microsimulation model of HIV disease and treatment (CEPAC-International) and data from Brazil to estimate life expectancy increase for HIV-positive patients initiating ART in Brazil. We divided the period of 1997 to 2014 into six eras reflecting increased drug regimen efficacy, regimen availability and era-specific mean CD4 count at ART initiation. Patients were simulated first without ART and then with ART. The 2014-censored and lifetime survival benefits attributable to ART in each era were calculated as the product of the number of patients initiating ART in a given era and the increase in life expectancy attributable to ART in that era. Results In total, we estimated that 598,741 individuals initiated ART. Projected life expectancy increased from 2.7, 3.3, 4.1, 4.9, 5.5 and 7.1 years without ART to 11.0, 17.5, 20.7, 23.0, 25.3, and 27.0 years with ART in Eras 1 through 6, respectively. Of the total projected lifetime survival benefit of 9.3 million life-years, 16% (or 1.5 million life-years) has been realized as of December 2014. Conclusions Provision of ART through a national programme has led to dramatic survival benefits in Brazil, the majority of which are still to be realized. Improvements in initial and subsequent ART regimens and higher CD4 counts at ART initiation have contributed to these increasing benefits. PMID:27029828

  10. Generalized drought assessment in Dongliao river basin based on water resources system

    Science.gov (United States)

    Weng, B. S.; Yan, D. H.; Wang, H.; Qin, T. L.; Yin, J.

    2014-11-01

    Drought is firstly a resource issue, and with its development it transforms into a disaster issue. The occurrences of drought events usually feature determinacy and randomness. Drought issue has become one of the major factors to affect sustainable economic and social development. In this paper, we propose the generalized drought assessment index (GDAI) based on water resources system for assessing drought events. The GDAI considers water supply and water demand using a distributed hydrological model. We demonstrate the use of the proposed index in the Dongliao river basin (DRB) in the northeast China. The results simulated by the GDAI are then compared to observed drought disaster records in DRB. As second, the temporal distribution of drought events and the spatial distribution of drought frequency from the GDAI are compared with the traditional approach (i.e. the SPI, the PDSI, and the RWD). Then, generalized drought times (GDT), generalized drought duration (GDD), and generalized drought severity (GDS) were calculated by theory of runs. Application of the GDT, the GDD, and the GDS of various drought levels (i.e. mild drought, moderate drought, severe drought, and extreme drought) to the period 1960-2010 shows that the centers of gravity of them are all distributed in the middle reached of DRB, and change with time. The proposed methodology helps water managers in water-stressed regions to quantify the impact of drought, consequently, to make decisions regarding coping with drought issue.

  11. Simulation of a Severe Autumn/Winter Drought in Eastern China by Regional Atmospheric Modeling System(RAMS)

    Science.gov (United States)

    Meng, Chunchun; Ma, Yaoming

    2016-04-01

    Compared with European Centre for Medium-Range Weather Forecasts (ERA-interim) Reanalysis data and Global Summary Of Day (GSOD) observation data, the outcomes from RAMS of the 2008/2009 severe autumn/winter drought in eastern china are analyzed in this study. The reanalysis data showed that most parts of north China are controlled by northwest wind which was accompanied by cold air, the warm and moist air from South Sea is so weak to meet with cold air, therefore forming a circulation which is unfavorable for the formation of precipitation over Eastern China. RAMS performs very well over the simulation of this atmospheric circulation, so do the rainfall and air temperature over China and where the drought occurred. Meanwhile, the simulation of the time series of precipitation and temperature behaves excellent, the square of correlation coefficient between simulations and observations reached above 0.8. Although the performance of RAMS on this drought simulation is fairly accurate, there is amount of research work to be continued to complete a more realistic simulation. KEY WORDS RAMS; severe drought; numerical simulation; atmospheric circulation; precipitation and air temperature

  12. Hydro-Economic Modeling with Minimum Data Requirements: An Application to the São Francisco River Basin, Brazil

    Science.gov (United States)

    Torres, M.; Maneta, M.; Vosti, S.; Wallender, W.; Howitt, R.

    2008-12-01

    Policymakers have been charged with the efficient, equitable, and sustainable use of water resources of the São Francisco River Basin (SFRB), Brazil, and also with the promotion of economic growth and the reduction of poverty within the basin. To date, policymakers lack scientific evidence on the potential consequences for growth, poverty alleviation or environmental sustainability of alternative uses of water resources. To address these key knowledge gaps, we have linked a hydrologic and an economic model of agriculture to investigate how economic decisions affect available water, and vice versa. More specifically, the models are used to predict the effects of the application of Brazilian federal surface water use policies on farmer's net revenues and on the hydrologic system. The Economic Model of Agriculture. A spatially explicit, farm-level model capable of accommodating a broad array of farm sizes and farm/farmer characteristics is developed and used to predict the effects of alternative water policies and neighbors' water use patterns on crop mix choice. A production function comprised of seven categories of non-water-related inputs used in agriculture (land, fertilizers, pesticides, seeds, hired labor, family labor and machinery) and four water-related inputs used in agriculture (applied water, irrigation labor, irrigation capital and energy) is estimated. The parameters emerging from this estimated production function are then introduced into a non-linear, net revenue maximization positive mathematical programming algorithm that is used for simulations. The Hydrological Model. MIKE Basin, a semi-distributed hydrology model, is used to calculate water budgets for the SFRB. MIKE Basin calculates discharge at selected nodes by accumulating runoff down the river network; it simulates reservoirs using stage-area-storage and downstream release rule curves. The data used to run the model are discharge to calculate local runoff, precipitation, reference ET, crop

  13. Functional Genomics of Drought Tolerance in Bioenergy Crops

    Energy Technology Data Exchange (ETDEWEB)

    Yin, Hengfu [ORNL; Chen, Rick [ORNL; Yang, Jun [ORNL; Weston, David [ORNL; Chen, Jay [ORNL; Muchero, Wellington [ORNL; Ye, Ning [ORNL; Tschaplinski, Timothy J [ORNL; Wullschleger, Stan D [ORNL; Cheng, Zong-Ming [ORNL; Tuskan, Gerald A [ORNL; Yang, Xiaohan [ORNL

    2014-01-01

    With the predicted trends in climate change, drought will increasingly impose a grand challenge to biomass production. Most of the bioenergy crops have some degree of drought susceptibility with low water-use efficiency (WUE). It is imperative to improve drought tolerance and WUE in bioenergy crops for sustainable biomass production in arid and semi-arid regions with minimal water input. Genetics and functional genomics can play a critical role in generating knowledge to inform and aid genetic improvement of drought tolerance in bioenergy crops. The molecular aspect of drought response has been extensively investigated in model plants like Arabidopsis, yet our understanding of the molecular mechanisms underlying drought tolerance in bioenergy crops are limited. Crops exhibit various responses to drought stress depending on species and genotype. A rational strategy for studying drought tolerance in bioenergy crops is to translate the knowledge from model plants and pinpoint the unique features associated with individual species and genotypes. In this review, we summarize the general knowledge about drought responsive pathways in plants, with a focus on the identification of commonality and specialty in drought responsive mechanisms among different species and/or genotypes. We describe the genomic resources developed for bioenergy crops and discuss genetic and epigenetic regulation of drought responses. We also examine comparative and evolutionary genomics to leverage the ever-increasing genomics resources and provide new insights beyond what has been known from studies on individual species. Finally, we outline future exploration of drought tolerance using the emerging new technologies.

  14. Location model of specialized terminals for soybe an exports in Brazil

    Directory of Open Access Journals (Sweden)

    Alessandra Fraga Dubke

    2011-04-01

    Full Text Available The purpose of this work is the development of a location model for specialized terminals used as transshipment points in the supply chain of soybeans. The theoretical basis of the study relies on the association of a transshipment model with a multi-commodity, multi-facility capacitated location model. The shipping ports might be seen as specialized terminals that add value to the exported products by transforming raw soy grains into soy oil and soy meal. The proposed model also considers service activities in each terminal and the capacity of the maritime ports. Using representative data from the year 2004, the model is illustrated by a small case study, which considers six points of production in inland Brazil, all served by railways, one maritime port on the north and five on the east coast, and three destination ports in Europe and Asia. The study includes a rough sensitivity analysis regarding volumes, capacities, prices, and transportation costs

  15. Monitoring agricultural drought with climate-based drought indices in China

    Science.gov (United States)

    Wang, H.; Zhang, C., Sr.; Jeffery, R. C.

    2015-12-01

    Agricultural drought monitoring significantly influences food security in recent decades. Soil moisture shortages adversely affecting agriculture is one important indicator for agricultural drought monitoring. Because of limited soil moisture observations, characterizing soil moisture using climate-based drought indices has great practical meaning. The agricultural area in China was identified by crop identification from remotely sensed data. Drought indices of multiple timescale or from two-layer bucket model were analyzed. In most agricultural areas of China, surface soil moisture is more affected by drought indices having shorter time scales while deep-layer soil moisture is more related on longer time scales. In general, multiscalar drought indices work better than drought indices from two-layer bucket models. The standardized precipitation evapotranspiration index (SPEI) works similarly or better than the standardized precipitation index (SPI) in characterizing soil moisture at different soil layers. In most stations in China, the Z index has a higher correlation with soil moisture at 0-5 cm than the Palmer drought severity index (PDSI), which in turn has a higher correlation with soil moisture at 90-100-cm depth than the Z index. Soil moisture-drought indices relationship was significantly affected by soil organic carbon density. Effective agriculture drought monitoring can be conducted with climate-based drought indices from widely available climatic data and crop area identification from remote sensing. Authors:Hongshuo wang1, Chao Zhang1, Jeffery C Rogers2 1 China agricultural university 2 Ohio state University Key words: Agricultural drought, SPI, SPEI, PDSI, Z index, crop identification

  16. Numerical modeling of failure mechanisms in phyllite mine slopes in Brazil

    Institute of Scientific and Technical Information of China (English)

    Lana Milene Sabino

    2014-01-01

    This paper presents three case studies comprising failure mechanisms in phyllite mine slopes at Quadrilá-tero Ferrífero, State of Minas Gerais, Brazil. Numerical modeling techniques were used in this study. Fail-ure mechanisms involving discontinuities sub parallel to the main foliation are very common in these mines. Besides, failure through the rock material has also been observed due to the low strength of phyl-lites in this site. Results of this work permitted to establish unknown geotechnical parameters which have significant influence in failure processes, like the in situ stress field and the discontinuity stiffness.

  17. A Predictive Model for Daily Inoculum Levels of Gibberella zeae in Passo Fundo, Brazil

    Directory of Open Access Journals (Sweden)

    Marcio Nicolau

    2012-01-01

    Full Text Available The deposition of spores of Gibberella zeae, the causal agent of Fusarium head blight of wheat, was monitored during 2008–2011, in Passo Fundo, RS, Brazil. The sampling was carried out in a 31-day period around wheat flowering. The numbers of colonies formed were related to meteorological variables. In this study, a hierarchical autoregressive binary data model was used. The model relates a binary response variable to potential covariates while accounting for dependence over discrete time points. This paper proposes an approach for both model parameter inference and prediction at future time points using the Markov chain Monte Carlo (MCMC. The developed model appeared to have a high degree of accuracy and may have implications in the disease control and risk-management planning.

  18. Droughts in the Czech Lands: Past, Present and Future

    Science.gov (United States)

    Brázdil, Rudolf; Trnka, Miroslav

    2015-04-01

    The presentation highlights main results of the InterDrought project (2013-2015), which includes several Czech universities and research institutes, and also shows overview of multidisciplinary scientific monograph on drought. The basic data sources consisting of instrumental, documentary, tree-ring and satellite data are presented. Selected drought indices (SPI, SPEI, Z-index and PDSI) calculated from homogenised Czech temperature and precipitation series are used to describe spatial and temporal variability of droughts in the Czech Lands for the 1804-2010 period including selection of drought extreme episodes and their detail description with respect to meteorological and synoptic patterns and impacts as well. Analysis of droughts prior 1804 is based on documentary data and oak tree-ring widths used for compilation of 500-year Czech drought chronology. The occurrence of extreme droughts is further analysed with respect to sea-level pressure patterns in the Atlantic-European area, climate forcings and changes in land-use. Examples of agricultural and hydrological droughts are mentioned. High resolution soil moisture models are used to estimate drought trends in last five decades as well as estimate future development of droughts in the Czech Republic. Overview represented by this paper will be complemented by several individual detail studies of other InterDrought Team members.

  19. A Global Grassland Drought Index (GDI Product: Algorithm and Validation

    Directory of Open Access Journals (Sweden)

    Binbin He

    2015-09-01

    Full Text Available Existing drought indices have been widely used to monitor meteorological drought and agricultural drought; however, few of them are focus on drought monitoring for grassland regions. This study presented a new drought index, the Grassland Drought Index (GDI, for monitoring drought conditions in global grassland regions. These regions are vital for the environment and human society but susceptible to drought. The GDI was constructed based on three measures of water content: precipitation, soil moisture (SM, and canopy water content (CWC. The precipitation information was extracted from the available precipitation datasets, and SM was estimated by downscaling exiting soil moisture data to a 1 km resolution, and CWC was retrieved based on the PROSAIL (PROSPECT + SAIL model. Each variable was scaled from 0 to 1 for each pixel based on absolute minimum and maximum values over time, and these scaled variables were combined with the selected weights to construct the GDI. According to validation at the regional scale, the GDI was correlated with the Standardized Precipitation Index (SPI to some extent, and captured most of the drought area identified by the United States Drought Monitor (USDM maps. In addition, the global GDI product at a 1 km spatial resolution substantially agreed with the global Standardized Precipitation Evapotranspiration Index (SPEI product throughout the period 2005–2010, and it provided detailed and accurate information about the location and the duration of drought based on the evaluation using the known drought events.

  20. Use of Land Surface Temperature Observations in a Two-Source Energy Balance Model Towards Improved Monitoring of Evapotranspiration and Drought

    Science.gov (United States)

    Hain, C.; Anderson, M. C.; Otkin, J.; Semmens, K. A.; Zhan, X.; Fang, L.; Li, Z.

    2014-12-01

    As the world's water resources come under increasing tension due to the dual stressors of climate change and population growth, accurate knowledge of water consumption through evapotranspiration (ET) over a range in spatial scales will be critical in developing adaptation strategies. However, direct validation of ET models is challenging due to lack of available observations that are sufficiently representative at the model grid scale (10-100 km). Prognostic land-surface models require accurate information about observed precipitation, soil moisture storage, groundwater, and artificial controls on water supply (e.g., irrigation, dams, etc.) to reliably link rainfall to evaporative fluxes. In contrast, diagnostic estimates of ET can be generated, with no prior knowledge of the surface moisture state, by energy balance models using thermal-infrared remote sensing of land-surface temperature (LST) as a boundary condition. One such method, the Atmosphere Land Exchange Inverse (ALEXI) model provides estimates of surface energy fluxes through the use of mid-morning change in LST and radiation inputs. The LST inputs carry valuable proxy information regarding soil moisture and its effect on soil evaporation and canopy transpiration. Additionally, the Evaporative Stress Index (ESI) representing anomalies in the ratio of actual-to-potential ET has shown to be a reliable indicator of drought. ESI maps over the continental US show good correspondence with standard drought metrics and with patterns of precipitation, but can be generated at significantly higher spatial resolution due to a limited reliance on ground observations. Furthermore, ESI is a measure of actual stress rather than potential for stress, and has physical relevance to projected crop development. Because precipitation is not used in construction of the ESI, it provides an independent assessment of drought conditions and has particular utility for real-time monitoring in regions with sparse rainfall data or

  1. A PROPOSAL FORECASTING MODEL FOR THE GROWTH OF THE MOBILE TELEPHONE MARKET IN BRAZIL

    Directory of Open Access Journals (Sweden)

    Luís Fernando Ascenção Guedes

    2009-10-01

    Full Text Available The element that characterizes the information era is the key role of communication and connectivity, broadly speaking, in social life. Among the ways in which users can enter voice or data networks, one of the most prominent is mobile telephony.Therefore, determining the number of mobile phones in operation in Brazil over the next few years is a relevant issue for the strategic planning of firms in this sector. Thus, this article aims to define a mathematical model suitable for calculating the number of mobile phones in operation in Brazil in forthcoming years, as a function of the behavior of the following variables during the course of time: GDP per capita, population and percentage GDP growth.To this end, a quantitative study was conducted, based on secondary data taken from preceding survey; then a linear and polynomial regression was employed to correlate GDP per capita with mobile phone density. The results showed high correlation (97.5% between phone density and Brazil’s GDP growth from 2004 to 2007. This correlation is also high in Russia, India and China.Moreover, we found that the limiting value of good correlation between GDP per capita and mobile phone density is roughly US$20,000.00 and that the limit of mobile telephony penetration is approximately 120%. Thus, taking into account several economic growth rates, we estimate that the penetration of mobile telephony will take 5 to 11 years to reach its upper limit in Brazil.Key words: Mobile telephony. Prediction model. Telecommunications.

  2. How 21st century droughts affect food and environmental security

    Science.gov (United States)

    Kogan, Felix

    The first 13th years of the 21st century has begun with a series of widespread, long and intensive droughts around the world. Extreme and severe-to-extreme intensity droughts covered 2-6% and 7-16% of the world land, respectively, affecting environment, economies and humans. These droughts reduced agricultural production, leading to food shortages, human health deterioration, poverty, regional disturbances, population migration and death. This presentation is a travelogue of the 21st century global and regional droughts during the warmest years of the past 100 years. These droughts were identified and monitored with the NOAA operational space technology, called Vegetation Health (VH), which has the longest period of observation and provide good data quality. The VH method was used for assessment of vegetation condition or health, including drought early detection and monitoring. The VH method is based on operational satellites data estimating both land surface greenness (NDVI) and thermal conditions. The 21st century droughts in the USA, Russia, Australia Argentina, Brazil, China, India and other principal grain producing countries were intensive, long, covered large areas and caused huge losses in agricultural production, which affected food and environmental security and led to food riots in some countries. This presentation investigate how droughts affect food and environmental security, if they can be detected earlier, how to monitor their area, intensity, duration and impacts and also their dynamics during the climate warming era with satellite-based vegetation health technology.

  3. Towards pan-European drought risk maps: quantifying the link between drought indices and reported drought impacts

    International Nuclear Information System (INIS)

    Drought in Europe is a hazard with a wide range of transboundary, environmental and socio-economic impacts on various sectors including agriculture, energy production, public water supply and water quality. Despite the apparent importance of this natural hazard, observed pan-European drought impacts have not yet been quantitatively related to the most important climatological drivers to map drought risk on a continental scale. This contribution approaches the issue by quantitatively assessing the likelihood of drought impact occurrence as a function of the standardized precipitation evapotranspiration index for four European macro regions using logistic regression. The resulting models allow mapping the sector-specific likelihood of drought impact occurrence for specific index levels. For the most severe drought conditions the maps suggest the highest risk of impact occurrence for ‘Water Quality’ in Maritime Europe, followed by ‘Agriculture and Livestock Farming’ in Western Mediterranean Europe and ‘Energy and Industry’ in Maritime Europe. Merely impacts on ‘Public Water Supply’ result in overall lower risk estimates. The work suggests that modeling and mapping for North- and Southeastern Europe requires further enhancement to the impact database in these regions. Such maps may become an essential component of drought risk management to foster resilience for this hazard at large scale. (letter)

  4. Towards pan-European drought risk maps: quantifying the link between drought indices and reported drought impacts

    Science.gov (United States)

    Blauhut, Veit; Gudmundsson, Lukas; Stahl, Kerstin

    2015-01-01

    Drought in Europe is a hazard with a wide range of transboundary, environmental and socio-economic impacts on various sectors including agriculture, energy production, public water supply and water quality. Despite the apparent importance of this natural hazard, observed pan-European drought impacts have not yet been quantitatively related to the most important climatological drivers to map drought risk on a continental scale. This contribution approaches the issue by quantitatively assessing the likelihood of drought impact occurrence as a function of the standardized precipitation evapotranspiration index for four European macro regions using logistic regression. The resulting models allow mapping the sector-specific likelihood of drought impact occurrence for specific index levels. For the most severe drought conditions the maps suggest the highest risk of impact occurrence for ‘Water Quality’ in Maritime Europe, followed by ‘Agriculture & Livestock Farming’ in Western Mediterranean Europe and ‘Energy & Industry’ in Maritime Europe. Merely impacts on ‘Public Water Supply’ result in overall lower risk estimates. The work suggests that modeling and mapping for North- and Southeastern Europe requires further enhancement to the impact database in these regions. Such maps may become an essential component of drought risk management to foster resilience for this hazard at large scale.

  5. Water Quality-Quantity Evaluation of the Ribeirão das Posses Watershed, Brazil, applying the AgES-W model.

    Science.gov (United States)

    Green, T. R.; Cruz, P. P. N. D.; Figueiredo, R. D. O.; Camargo, P. B. D.; Santos, C. P.

    2015-12-01

    Southeastern Brazil is under a period of drought that has impacted the conservation of watersheds and the management of water quality and quantity for agricultural and urban demands. In this context agro-hydrological modeling tools can generate information of water response over time in response to climate and landuse changes. A 12-km2 watershed which has suffered from anthropogenic activities is the Ribeirão das Posses watershed that is located in the extreme south of Minas Gerais State and is a headwater catchment of the Jaguari river, one of the contributing rivers of the Cantareira Reservoir Complex in the state of São Paulo. This watershed had its landscape changed over the last century from native forests to more homogeneous vegetation for pastures and small crops and some forest plantations fragments with eucalyptus. Currently, the Conservative Waters project has planted some small areas with vegetation of native species, especially where there are springs and at the top of the hills, in order to recover degraded areas and improve the hydrogeochemistry in this study basin. In this context, the AgroEcoSystem-Watershed (AgES-W) model is presented to simulate the water movement and storage in agricultural watersheds with different spatial resolutions of land areas or hydrological responses units. The objectives are to evaluate the quality and quantity of water in Ribeirão das Posses Basin using measured data, then simulate these responses in space and time to test the AgES-W model. The period chosen for research was from 2011 to 2015, because the water quality data were collected during this period. The answers that we hope to find out are: How well does the AgES-W model simulate this Brazilian watershed in the tropics? What are the future prospects of the quality and quantity of water in this basin? The results will help to guide hydrological simulations in similar tropical environments in Brazil in this and other agricultural watersheds with AgES-W.

  6. Precipitation variability, extremes and uncertainties over southeastern Brazil projected by the Eta regional model

    Science.gov (United States)

    Cavalcanti, Iracema; Silveira, Virginia; Chan, Chou; Marengo, Jose Antonio

    2014-05-01

    Southeastern Brazil is an area affected by extreme precipitation, mainly in the austral summer, associated with frontal systems or the South Atlantic Convergence Zone (SACZ). Flooding and landslides have occurred in the region with serious impact on society and economy. The region has many vulnerable areas, therefore, projections of precipitation and extremes in the future for the region are important to provide information that can be used in adaptations and management decisions. Results of regional models in South America have been analyzed to assess the future climate changes with higher resolution than global models. In this study the Regional Eta model is used with resolution of 40 and 20 Km to analyze the projections of precipitation changes and extremes over Brazil and mainly over the southeastern region. Simulations and projections obtained from four integrations of the Regional Eta model are analyzed to investigate the model behavior during the period of 1961-1990 and the projections in the near (2011 to 2040) and more distant future (2041 to 2100). Results from four integrations with resolution of 40 km with different lateral boundary conditions from the HadCM3 Global Model and one integration with resolution of 20 km are used to give a confidence interval and the related uncertainty. The first analysis was to verify changes in the main mode of precipitation variability in the future projections, compared to the base period. There is a change in the main centers of extremes variability over South America, which was comparable to changes projected in CMIP5 models. The second analysis was related to changes in the position and intensity of the SACZ. Specific locations in southeastern Brazil were analyzed regarding indices of extremes, such as SDII (mean precipitation of rainy days), SDII_10 (mean precipitation of rainy days >=10 mm/day), R10mm (number of days with precipitation >= 10 mm/day), CDD (maximum number of consecutive dry days), CWD (maximum number

  7. Using plant growth modeling to analyze C source–sink relations under drought: inter- and intraspecific comparison

    OpenAIRE

    Pallas, Benoît; Clément-Vidal, Anne; Rebolledo, Maria-Camila; Soulié, Jean-Christophe; Luquet, Delphine

    2013-01-01

    The ability to assimilate C and allocate non-structural carbohydrates (NSCs) to the most appropriate organs is crucial to maximize plant ecological or agronomic performance. Such C source and sink activities are differentially affected by environmental constraints. Under drought, plant growth is generally more sink than source limited as organ expansion or appearance rate is earlier and stronger affected than C assimilation. This favors plant survival and recovery but not always agronomic per...

  8. Using plant growth modeling to analyse C source-sink relations under drought: inter and intra specific comparison

    OpenAIRE

    Benoit ePallas; Anne eClément-Vidal; Maria-Camila eRebolledo; Jean-Christophe eSoulié; Delphine eLuquet

    2013-01-01

    The ability to assimilate C and allocate NSC (non structural carbohydrates) to the most appropriate organs is crucial to maximize plant ecological or agronomic performance. Such C source and sink activities are differentially affected by environmental constraints. Under drought, plant growth is generally more sink than source limited as organ expansion or appearance rate is earlier and stronger affected than C assimilation. This favors plant survival and recovery but not always agronomic perf...

  9. Large-scale hydrological modelling in the semi-arid north-east of Brazil

    Science.gov (United States)

    Güntner, Andreas

    2002-07-01

    Semi-arid areas are, due to their climatic setting, characterized by small water resources. An increasing water demand as a consequence of population growth and economic development as well as a decreasing water availability in the course of possible climate change may aggravate water scarcity in future, which often exists already for present-day conditions in these areas. Understanding the mechanisms and feedbacks of complex natural and human systems, together with the quantitative assessment of future changes in volume, timing and quality of water resources are a prerequisite for the development of sustainable measures of water management to enhance the adaptive capacity of these regions. For this task, dynamic integrated models, containing a hydrological model as one component, are indispensable tools. The main objective of this study is to develop a hydrological model for the quantification of water availability in view of environmental change over a large geographic domain of semi-arid environments. The study area is the Federal State of Ceará (150 000 km2) in the semi-arid north-east of Brazil. Mean annual precipitation in this area is 850 mm, falling in a rainy season with duration of about five months. Being mainly characterized by crystalline bedrock and shallow soils, surface water provides the largest part of the water supply. The area has recurrently been affected by droughts which caused serious economic losses and social impacts like migration from the rural regions. The hydrological model Wasa (Model of Water Availability in Semi-Arid Environments) developed in this study is a deterministic, spatially distributed model being composed of conceptual, process-based approaches. Water availability (river discharge, storage volumes in reservoirs, soil moisture) is determined with daily resolution. Sub-basins, grid cells or administrative units (municipalities) can be chosen as spatial target units. The administrative units enable the coupling of Wasa in

  10. Forecasts of Agricultural Drought in Sri Lanka

    Science.gov (United States)

    Gilligan, J. M.; Gunda, T.; Hornberger, G. M.

    2015-12-01

    As the most frequent natural disaster in Sri Lanka, drought greatly affects crop production and livelihoods. Over half of all agricultural crop damage in Sri Lanka is currently due to drought; the frequency and severity of drought in the country is only expected to increase with the changing climate. Previous work indicates that the Palmer Drought Severity Index (PDSI) and Standardized Precipitation Index (SPI) are capable of capturing agricultural drought patterns (between 1881-2010) in the island nation. In this work, PDSI and SPI from 13 long-term meteorological stations will be projected into the future using a combination of artificial neural network and autoregressive integrated moving average models. The impacts of large-scale atmospheric circulation patterns (such as the Niño 3.4 index, a measure of sea surface temperature) and lead times on projection accuracy will also be explored. Model projections will be compared to weather data since 2010 to determine if the 2014 drought could have been forecasted using these methods. Since agricultural systems are strongly influenced by both natural and human systems, it is important to frame these physical findings within a social context. This work is part of an interdisciplinary project that assesses the perceptions of and adaptations to drought by rice farmers in Sri Lanka; disciplines represented in the group include hydrology, social psychology, ethnography, policy, and behavioral economics. Insights from the diverse research perspectives within the group will be drawn upon to highlight the social implications of the physical results.

  11. Modeling sugarcane ripening as a function of accumulated rainfall in Southern Brazil

    Science.gov (United States)

    Cardozo, Nilceu P.; Sentelhas, Paulo C.; Panosso, Alan R.; Palhares, Antonio L.; Ide, Bernardo Y.

    2015-12-01

    The effect of weather variables on sugarcane ripening is a process still not completely understood, despite its huge impact on the quality of raw material for the sugar energy industry. The aim of the present study was to evaluate the influence of weather variables on sugarcane ripening in southern Brazil, propose empirical models for estimating total recoverable sugar (TRS) content, and evaluate the performance of these models with experimental and commercial independent data from different regions. A field experiment was carried out in Piracicaba, in the state of São Paulo, Brazil, considering eight sugarcane cultivars planted monthly, from March to October 2002. In 2003, at the harvest, 12 months later, samples were collected to evaluate TRS (kg t-1). TRS and weather variables (air temperature, solar radiation, relative humidity, and rainfall) were analyzed using descriptive and multivariate statistical analysis to understand their interactions. From these correlations, variables were selected to generate empirical models for estimating TRS, according to the cultivar groups and their ripening characteristics (early, mid, and late). These models were evaluated by residual analysis and regression analysis with independent experimental data from two other locations in the same years and with independent commercial data from six different locations from 2005 to 2010. The best performances were found with exponential models which considered cumulative rainfall during the 120 days before harvest as an independent variable ( R 2 adj ranging from 0.92 to 0.95). Independent evaluations revealed that our models were capable of estimating TRS with reasonable to high precision ( R 2 adj ranging from 0.66 to 0.99) and accuracy ( D index ranging from 0.90 to 0.99), and with low mean absolute percentage errors (MAPE ≤ 5 %), even in regions with different climatic conditions.

  12. Drought, Climate Change and Potential Agricultural Productivity

    Science.gov (United States)

    Sheffield, J.; Herrera-Estrada, J. E.; Caylor, K. K.; Wood, E. F.

    2011-12-01

    Drought is a major factor in agricultural productivity, especially in developing regions where the capacity for water resources management is limited and climate variability ensures that drought is recurrent and problematic. Recent events in East Africa are testament to this, where drought conditions that have slowly developed over multiple years have contributed to reduced productivity and ultimately food crises and famine. Prospects for the future are not promising given ongoing problems of dwindling water supplies from non-renewable sources and the potential for increased water scarcity and increased drought with climate change. This is set against the expected increase in population by over 2 billion people by 2050 and rise in food demand, coupled with changes in demographics that affect food choices and increases in non-food agriculture. In this talk we discuss the global variability of drought over the 20th century and recent years, and the projected changes over the 21st century, and how this translates into changes in potential agricultural productivity. Drought is quantified using land surface hydrological models driven by a hybrid reanalysis-observational meteorological forcing dataset. Drought is defined in terms of anomalies of hydroclimatic variables, in particular precipitation, evaporation and soil moisture, and we calculate changes in various drought characteristics. Potential agricultural productivity is derived from the balance of precipitation to crop water demand, where demand is based on potential evaporation and crop coefficients for a range of staple crops. Some regional examples are shown of historic variations in drought and potential productivity, and the estimated water deficit for various crops. The multitude of events over the past decade, including heat waves in Europe, fires in Russia, long-term drought in northern China, southeast Australia, the Western US and a series of droughts in the Amazon and Argentina, hint at the influence of

  13. GEOWOW: a drought scenario for multidisciplinary data access and use

    Science.gov (United States)

    Santoro, Mattia; Sorichetta, Alessandro; Roglia, Elena; Craglia, Massimo; Nativi, Stefano

    2013-04-01

    Recent enhancements of the GEOSS Common Infrastructure (GCI; http://www.earthobservations.org/gci_gci.shtml), and in particular the introduction of a middleware in the GCI that brokers across heterogeneous information systems, have increased significantly the number of information resources discoverable worldwide. Now the challenge moves to the next level of ensuring access and use of the resources discovered, which have many different and domain-specific data models, communication protocols, encoding formats, etc. The GEOWOW Project - GEOSS interoperability for Weather, Ocean and Water, http://www.geowow.eu - developed a set of multidisciplinary use scenarios to advance the present GCI. This work describes the "Easy discovery and use of GEOSS resources for addressing multidisciplinary challenges related to drought scenarios" showcase demonstrated at the last GEO Plenary in Foz de Iguazu (Brazil). The scientific objectives of this showcase include: prevention and mitigation of water scarcity and drought situations, assessment of the population and geographical area potentially affected, evaluation of the possible distribution of mortality and economic loss risk, and support in building greater capacity to cope with drought. The need to address these challenges calls for producing scientifically robust and consistent information about the extent of land affected by drought and degradation. Similarly, in this context it is important: (i) to address uncertainties about the way in which various biological, physical, social, and economic factors interact each other and influence the occurrence of drought events, and (ii) to develop and test adequate indices and/or combination of them for monitoring and forecasting drought in different geographic locations and at various spatial scales (Brown et al., 2002). The scientific objectives above can be met with an increased interoperability across the multidisciplinary domains relevant to this drought scenario. In particular

  14. Comparative analysis of integrated water resources management models and instruments in South America: case studies in Brazil and Colombia

    Directory of Open Access Journals (Sweden)

    Raquel dos Santos

    2013-04-01

    Full Text Available Brazil and Colombia are rich in terms of water supply, ranking as world leaders in the supply of water resources. Despite this, both countries have problems of relative scarcity of this vital liquid in highly populated areas with much economic activity. Establishing policies and legal environmental standards has long tradition in both countries. However, although there are provisions and instruments for water management at the water basin level, these do not necessarily follow the conceptual development of integrated water resources management (IWRM. As a result, the two countries have partially implemented IWRM elements but with different characteristics both in its structure and instrumentality. In Colombia the State Government, through the Regional Environmental Corporations, implements IWRM (concessions, fee for water use, pollution rate, basin plans, etc, with no formal involvement of civil society management. In Brazil, however, IWRM management structure and tools are decentralized and participatory, as are the Water Basin Committees, entities where the State Government, municipalities and users participate, those with the greatest weight in water management. In Brazil, however, this model is not yet implemented in all watersheds. Thus, the aim of this paper is to compare the institutional and legal aspects of water management models in Brazil and Colombia with regard to the integrated water management concept. For the latter, we worked with a case study for each country regarding Nima River watershed (Colombia and Tietê Jacaré (Brazil.

  15. The meat market: a dea international perspective and an econometric behavioral model for Brazil

    Directory of Open Access Journals (Sweden)

    Geraldo da Silva e Souza

    2014-09-01

    Full Text Available We describe the relative participation of the Brazilian meat market (beef, pork and chicken in total agribusiness exports and in total country exports. An analysis of the world meat market is carried out from the point of view of the values of consumption, production, exports and imports. A DEA (data envelopment analysis approach is then used to generate classifications of the importance of countries in the meat world market, and the insertion of Brazil into this market is viewed from these perspectives. A partial equilibrium model for the meat market is fitted to Brazilian data by a three-stage least squares procedure. The model is consistent with the data and is used for simulation purposes. In this context, we investigate the joint and separate effects of changes in the corn price and in the exchange rate on the market of endogenous variables, ceteris paribus.

  16. Agricultural Productivity Forecasts for Improved Drought Monitoring

    Science.gov (United States)

    Limaye, Ashutosh; McNider, Richard; Moss, Donald; Alhamdan, Mohammad

    2010-01-01

    Water stresses on agricultural crops during critical phases of crop phenology (such as grain filling) has higher impact on the eventual yield than at other times of crop growth. Therefore farmers are more concerned about water stresses in the context of crop phenology than the meteorological droughts. However the drought estimates currently produced do not account for the crop phenology. US Department of Agriculture (USDA) and National Oceanic and Atmospheric Administration (NOAA) have developed a drought monitoring decision support tool: The U.S. Drought Monitor, which currently uses meteorological droughts to delineate and categorize drought severity. Output from the Drought Monitor is used by the States to make disaster declarations. More importantly, USDA uses the Drought Monitor to make estimates of crop yield to help the commodities market. Accurate estimation of corn yield is especially critical given the recent trend towards diversion of corn to produce ethanol. Ethanol is fast becoming a standard 10% ethanol additive to petroleum products, the largest traded commodity. Thus the impact of large-scale drought will have dramatic impact on the petroleum prices as well as on food prices. USDA's World Agricultural Outlook Board (WAOB) serves as a focal point for economic intelligence and the commodity outlook for U.S. WAOB depends on Drought Monitor and has emphatically stated that accurate and timely data are needed in operational agrometeorological services to generate reliable projections for agricultural decision makers. Thus, improvements in the prediction of drought will reflect in early and accurate assessment of crop yields, which in turn will improve commodity projections. We have developed a drought assessment tool, which accounts for the water stress in the context of crop phenology. The crop modeling component is done using various crop modules within Decision Support System for Agrotechnology Transfer (DSSAT). DSSAT is an agricultural crop

  17. Oral health in Brazil: the challenges for dental health care models.

    Science.gov (United States)

    Chaves, Sônia Cristina Lima

    2012-01-01

    This paper discusses adult oral health in Brazil according to three perspectives: 1) the available epidemiological evidence about the population's oral-health-related epidemiological situation, especially adults and the elderly population, in relation to two high prevalence oral injuries (dental caries and tooth loss), 2) the main health care models for dealing with this situation, by analyzing the related historical processes in order to reveal the likely social, political and epidemiological implications of the different models, and 3) lastly, the possible challenges to Brazilian dentistry or collective oral health in overcoming these obstacles. The main results of the study indicate that, from an epidemiological point of view, Brazil is undergoing a transition in dental caries and tooth loss, which is not yet reflected in the profile of the elderly, but which is tentatively evidenced in young adults. Tooth loss remains high. Certain aspects of society's economic and political superstructure have an important impact on oral health indicators and existing inequalities. Oral health care models have a relative importance and must not be neglected. Vestiges of ideological movements, like preventive medicine, may explain the current impasse in collective oral health practices, such as the preeminence of Finalized Treatment (FT) in clinics and of preventive care in schools fostered by community-based programs. It is therefore important to develop conceptual, theoretical reflections and to increase the objects of intervention, their purposes and their modus operandi. The practice of dentistry according to these alternative models is still being constructed. New studies related to the different formats of these new practices are recommended.

  18. Hydrological drought severity explained by climate and catchment characteristics

    Science.gov (United States)

    Van Loon, A. F.; Laaha, G.

    2015-07-01

    Impacts of a drought are generally dependent on the severity of the hydrological drought event, which can be expressed by streamflow drought duration or deficit volume. For prediction and the selection of drought sensitive regions, it is crucial to know how streamflow drought severity relates to climate and catchment characteristics. In this study we investigated controls on drought severity based on a comprehensive Austrian dataset consisting of 44 catchments with long time series of hydrometeorological data (on average around 50 year) and information on a large number of physiographic catchment characteristics. Drought analysis was performed with the variable threshold level method and various statistical tools were applied, i.e. bivariate correlation analysis, heatmaps, linear models based on multiple regression, varying slope models, and automatic stepwise regression. Results indicate that streamflow drought duration is primarily controlled by storage, quantified by the Base Flow Index or by a combination of catchment characteristics related to catchment storage and release, e.g. geology and land use. Additionally, the duration of dry spells in precipitation is important for streamflow drought duration. Hydrological drought deficit, however, is governed by average catchment wetness (represented by mean annual precipitation) and elevation (reflecting seasonal storage in the snow pack and glaciers). Our conclusion is that both drought duration and deficit are governed by a combination of climate and catchment control, but not in a similar way. Besides meteorological forcing, storage is important; storage in soils, aquifers, lakes, etc. influences drought duration and seasonal storage in snow and glaciers influences drought deficit. Consequently, the spatial variation of hydrological drought severity is highly dependent on terrestrial hydrological processes.

  19. Drought in Southwestern United States

    Science.gov (United States)

    2007-01-01

    The southwestern United States pined for water in late March and early April 2007. This image is based on data collected by the Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA's Terra satellite from March 22 through April 6, 2007, and it shows the Normalized Difference Vegetation Index, or NDVI, for the period. In this NDVI color scale, green indicates areas of healthier-than-usual vegetation, and only small patches of green appear in this image, near the California-Nevada border and in Utah. Larger areas of below-normal vegetation are more common, especially throughout California. Pale yellow indicates areas with generally average vegetation. Gray areas appear where no data were available, likely due to persistent clouds or snow cover. According to the April 10, 2007, update from the U.S. Drought Monitor, most of the southwestern United Sates, including Utah, Nevada, California, and Arizona, experienced moderate to extreme drought. The hardest hit areas were southeastern California and southwestern Arizona. Writing for the Drought Monitor, David Miskus of the Joint Agricultural Weather Facility reported that March 2007 had been unusually dry for the southwestern United States. While California's and Utah's reservoir storage was only slightly below normal, reservoir storage was well below normal for New Mexico and Arizona. In early April, an international research team published an online paper in Science noting that droughts could become more common for the southwestern United States and northern Mexico, as these areas were already showing signs of drying. Relying on the same computer models used in the Intergovernmental Panel on Climate Change (IPCC) report released in early 2007, the researchers who published in Science concluded that global warming could make droughts more common, not just in the American Southwest, but also in semiarid regions of southern Europe, Mediterranean northern Africa, and the Middle East.

  20. Drought Tolerance in Wheat

    Directory of Open Access Journals (Sweden)

    Arash Nezhadahmadi

    2013-01-01

    Full Text Available Drought is one of the most important phenomena which limit crops’ production and yield. Crops demonstrate various morphological, physiological, biochemical, and molecular responses to tackle drought stress. Plants’ vegetative and reproductive stages are intensively influenced by drought stress. Drought tolerance is a complicated trait which is controlled by polygenes and their expressions are influenced by various environmental elements. This means that breeding for this trait is so difficult and new molecular methods such as molecular markers, quantitative trait loci (QTL mapping strategies, and expression patterns of genes should be applied to produce drought tolerant genotypes. In wheat, there are several genes which are responsible for drought stress tolerance and produce different types of enzymes and proteins for instance, late embryogenesis abundant (lea, responsive to abscisic acid (Rab, rubisco, helicase, proline, glutathione-S-transferase (GST, and carbohydrates during drought stress. This review paper has concentrated on the study of water limitation and its effects on morphological, physiological, biochemical, and molecular responses of wheat with the possible losses caused by drought stress.

  1. Drought tolerance in potato (S. tuberosum L.): Can we learn from drought tolerance research in cereals?

    Science.gov (United States)

    Monneveux, Philippe; Ramírez, David A; Pino, María-Teresa

    2013-05-01

    Drought tolerance is a complex trait of increasing importance in potato. Our knowledge is summarized concerning drought tolerance and water use efficiency in this crop. We describe the effects of water restriction on physiological characteristics, examine the main traits involved, report the attempts to improve drought tolerance through in vitro screening and marker assisted selection, list the main genes involved and analyze the potential interest of native and wild potatoes to improve drought tolerance. Drought tolerance has received more attention in cereals than in potato. The review compares these crops for indirect selection methods available for assessment of drought tolerance related traits, use of genetic resources, progress in genomics, application of water saving techniques and availability of models to anticipate the effects of climate change on yield. It is concluded that drought tolerance improvement in potato could greatly benefit from the transfer of research achievements in cereals. Several promising research directions are presented, such as the use of fluorescence, reflectance, color and thermal imaging and stable isotope techniques to assess drought tolerance related traits, the application of the partial root-zone drying technique to improve efficiency of water supply and the exploitation of stressful memory to enhance hardiness.

  2. Comparison between Two Methods for agricultural drought disaster risk in southwestern China

    Science.gov (United States)

    han, lanying; zhang, qiang

    2016-04-01

    The drought is a natural disaster, which lead huge loss to agricultural yield in the world. The drought risk has become increasingly prominent because of the climatic warming during the past century, and which is also one of the main meteorological disasters and serious problem in southwestern China, where drought risk exceeds the national average. Climate change is likely to exacerbate the problem, thereby endangering Chinaʹs food security. In this paper, drought disaster in the southwestern China (where there are serious drought risk and the comprehensive loss accounted for 3.9% of national drought area) were selected to show the drought change under climate change, and two methods were used to assess the drought disaster risk, drought risk assessment model and comprehensive drought risk index. Firstly, we used the analytic hierarchy process and meteorological, geographic, soil, and remote-sensing data to develop a drought risk assessment model (defined using a comprehensive drought disaster risk index, R) based on the drought hazard, environmental vulnerability, sensitivity and exposure of the values at risk, and capacity to prevent or mitigate the problem. Second, we built the comprehensive drought risk index (defined using a comprehensive drought disaster loss, L) based on statistical drought disaster data, including crop yields, drought-induced areas, drought-occurred areas, no harvest areas caused by drought and planting areas. Using the model, we assessed the drought risk. The results showed that spatial distribution of two drought disaster risks were coherent, and revealed complex zonality in southwestern China. The results also showed the drought risk is becoming more and more serious and frequent in the country under the global climatic warming background. The eastern part of the study area had an extremely high risk, and risk was generally greater in the north than in the south, and increased from southwest to northeast. The drought disaster risk or

  3. [Analysis of contractual incentives for kidney transplants in Brazil using the principal-agent model].

    Science.gov (United States)

    Costa, Cassia Kely Favoretto; Balbinotto, Giácomo; Sampaio, Luciano Menezes Bezerra

    2016-01-01

    The aim of this article was to analyze contractual incentives for kidney transplants in Brazil based on the principal-agent model. The approach assumes that the Brazilian Ministry of Health is the principal and the public hospitals accredited by the National Transplant System are the agent. The Ministry of Health's welfare depends on measures taken by hospitals in kidney uptake. Hospitals allocate administrative, financial, and management efforts to conduct measures in kidney donation, removal, uptake, and transplantation. Hospitals may choose the levels of effort that are consistent with the payments and incentives received in relation to transplantation costs. The solution to this type of problem lies in structuring an optimal incentives contract, which requires aligning the interests of both parties involved in the transplantation system. PMID:27626647

  4. Drought management plans and water availability in agriculture: A risk assessment model for a Southern European basin

    Directory of Open Access Journals (Sweden)

    Carlos Dionisio Pérez-Blanco

    2014-08-01

    Full Text Available The Drought Management Plans (DMPs are regulatory instruments that establish priorities among the different water uses and define more stringent constraints to access to publicly provided water during droughts, especially for non-priority uses such as agriculture. These plans have recently become widespread across EU southern basins. However, in some of these basins the plans were approved without an assessment of the potential impacts that they may have on the economic activities exposed to water restrictions. This paper develops a stochastic methodology to estimate the expected water availability in agriculture that results from the decision rules of the recently approved DMPs. The methodology is applied to the particular case of the Guadalquivir River Basin in southern Spain. Results show that if DMPs are successfully enforced, available water will satisfy in average 62.2% of current demand, and this figure may drop to 50.2% by the end of the century as a result of climate change. This is much below the minimum threshold of 90% that has been guaranteed to irrigators so far.

  5. Assessing Urban Droughts in a Smart City Framework

    Science.gov (United States)

    Obringer, R.; Zhang, X.; Mallick, K.; Alemohammad, S. H.; Niyogi, D.

    2016-06-01

    This study aims to integrate environmental data for drought monitoring to reduce uncertainty in urban drought characterization as part of the smart city framework. Currently, drought monitoring in urban areas is a challenge. This is due, in part, to a lack of knowledge on the subject of urban droughts and urban drought vulnerability. A critical part to assessing urban drought and implementing the necessary policies is determining drought conditions. Often the timing and severity of the drought can leave cities to enforce water restrictions, so accuracy of this determination has socioeconomic implications. To determine drought conditions, we need to know the water balance over the urban landscape, of which evapotranspiration (ET) is a key variable. However, ET data and models have high uncertainty when compared to other hydrological variables (i.e., precipitation). This is largely due to ill-defined empirical models for characterizing the urban surface resistance parameter (rs) that is used in ET calculations. We propose a method to estimate rs values using a combination of the Surface Temperature Initiated Closure (STIC) method that calculates regional evapotranspiration data and an inverted version of the Penman-Monteith equation. We use this approach across the region surrounding Indianapolis, IN (USA) from 2010-2014. We discuss the potential for this method to be integrated in to smart city framework to improve urban drought assessment.

  6. Drought modes in West Africa and how well CORDEX RCMs simulate them

    Science.gov (United States)

    Diasso, Ulrich; Abiodun, Babatunde J.

    2015-12-01

    This study presents the spatial-temporal structure of droughts in West Africa and evaluates the capability of CORDEX regional climate models in simulating the droughts. The study characterize droughts with the standardized evapo-transpiration index (SPEI) computed using the monthly rainfall and temperature data from the Climatic Research Unit (CRU) and CORDEX models simulation datasets. To obtain the spatial-temporal structure of the droughts, we applied the principal component analysis on the observed and simulated SPEIs and retained the first four principal factors as the leading drought modes over West Africa. The relationship between the drought modes and atmospheric teleconnections was studied using wavelet coherence analysis, while the ability of the CORDEX models to simulate the drought modes was quantified with correlation analysis. The analysis of the relationship between drought modes and atmospheric teleconnections is based on SPEI from observation dataset (CRU). The study shows that about 60 % of spatial-temporal variability in SPEI over West Africa can be grouped into four drought modes. The first drought mode features drought over east Sahel, the second over west Sahel, the third over the Savanna, and the fourth over the Guinea coast. Each drought mode is linked to sea surface temperature anomalies (SSTAs) over tropical areas of Pacific, Atlantic, and Indian Oceans. Most CORDEX models reproduce at least two of the drought modes, but only two models (REMO and CNRM) reproduce all the four drought modes. REMO and WRF give the best simulation of the seasonal variation of the drought mode over the Sahel in March-May and June-August seasons, while CNRM gives the best simulation of seasonal variation in the drought pattern over the Savanna. Results of this study may guide in selecting appropriate CORDEX models for seasonal prediction of droughts and for downscaling projected impacts of global warming on droughts in West Africa.

  7. A USCLIVAR Project to Assess and Compare the Responses of Global Climate Models to Drought-Related SST Forcing Patterns: Overview and Results

    Science.gov (United States)

    Schubert, Siegfried; Wang, Hailan; Koster, Randal; Weaver, Scott; Gutzler, David; Dai, Aiguo; Delworth, Tom; Deser, Clara; Findell, Kristen; Fu, Rong; Higgins, Wayne; Hoerline, Martin; Kirtman, Ben; Kumar, Arun; Mo, Kingtse; Pegion, Philip; Phillips, Adam; Suarez, Max; Legler, David; Lettenmaier, Dennis; Lyon, Bradfield; Magana, Victor; Nigam, Sumant; Pulwarty, Roger; Rind, David

    2009-01-01

    The USCLI VAR working group on drought recently initiated a series of global climate model simulations forced with idealized SST anomaly patterns, designed to address a number of uncertainties regarding the impact of SST forcing and the role of land-atmosphere feedbacks on regional drought. Specific questions that the runs are designed to address include: What are the mechanisms that maintain drought across the seasonal cycle and from one year to the next? What is the role of the leading patterns of SST variability, and what are the physical mechanisms linking the remote SST forcing to regional drought, including the role of land-atmosphere coupling? The runs were carried out with five different atmospheric general circulation models (AGCM5), and one coupled atmosphere-ocean model in which the model was continuously nudged to the imposed SST forcing. This paper provides an overview of the experiments and some initial results focusing on the responses to the leading patterns of annual mean SST variability consisting of a Pacific El Nino/Southern Oscillation (ENSO)-like pattern, a pattern that resembles the Atlantic Multi-decadal Oscillation (AMO), and a global trend pattern. One of the key findings is that all the AGCMs produce broadly similar (though different in detail) precipitation responses to the Pacific forcing pattern, with a cold Pacific leading to reduced precipitation and a warm Pacific leading to enhanced precipitation over most of the United States. While the response to the Atlantic pattern is less robust, there is general agreement among the models that the largest precipitation response over the U.S. tends to occur when the two oceans have anomalies of opposite sign. That is, a cold Pacific and warm Atlantic tend to produce the largest precipitation reductions, whereas a warm Pacific and cold Atlantic tend to produce the greatest precipitation enhancements. Further analysis of the response over the U.S. to the Pacific forcing highlights a number of

  8. Past and Future Drought Regimes in Turkey

    Science.gov (United States)

    Sen, Burak; Topcu, Sevilay; Turkes, Murat; Sen, Baha

    2010-05-01

    Climate variability in the 20th century was characterized by apparent precipitation variability at both temporal and spatial scales. In addition to the well-known characteristic seasonal and year-to-year variability, some marked and long-term changes in precipitation occurred in Turkey, particularly after the early 1970s. Drought, originating from a deficiency of precipitation over an extended time period (which is usually a season or more) has become a recurring phenomenon in Turkey in the past few decades. Spatially coherent with the significant drought events since early 1970s, water stress and shortages for all water user sectors have also reached their critical points in Turkey. Analyzing the historical occurrence of drought provides an understanding of the range of climate possibilities for a country, resulting in more informed management decision-making. However, future projections about spatial and temporal changes in drought characteristics such as frequency, intensity and duration can be challenging for developing appropriate mitigation and adaptation strategies. Hence, the objectives of this study are (i) to analyze the spatial and temporal dimensions of historical droughts in Turkey, (2) to predict potential intensity, frequency and duration of droughts in Turkey for the future (2070-2100). The Standardized Precipitation Index (SPI) and the Percent to Normal Index (PNI) have been used to assess the drought characteristics. Rainfall datasets for the reference period, 1960-1990, were acquired from 52 stations (representative of all kinds of regions with different rainfall regimes in the country) of the Turkish State Meteorological Service (TSMS). The future rainfall series for the 2070-2100 period were simulated using a regional climate model (RegCM3) for IPCC's SRESS-A2 scenario conditions. For verification of RegCM3 simulations, the model was performed for the reference period and simulated rainfall data were used for computing two drought indices (SPI

  9. Remote Sensing of Drought: Progress and Opportunities for Improving Drought Monitoring

    Science.gov (United States)

    AghaKouchak, A.

    2015-12-01

    This presentation surveys current and emerging drought monitoring approaches using satellite remote sensing observations from climatological and ecosystem perspectives. We argue that satellite observations not currently used for operational drought monitoring, such as near-surface air relative humidity data from the Atmospheric Infrared Sounder (AIRS) mission, provide opportunities to improve early drought warning. Current and future satellite missions offer opportunities to develop composite and multi-indicator drought models. While there are immense opportunities, there are major challenges including data continuity, unquantified uncertainty, sensor changes, and community acceptability. One of the major limitations of many of the currently available satellite observations is their short length of record. A number of relevant satellite missions and sensors (e.g., the Gravity Recovery and Climate Experiment, GRACE) provide only a decade of data, which may not be sufficient to study droughts from a climate perspective. However, they still provide valuable information about relevant hydrologic and ecological processes linked to this natural hazard. Therefore, there is a need for models and algorithms that combine multiple datasets and/or assimilate satellite observations into model simulations to generate long-term climate data records. Finally, the study identifies a major gap in indicators for describing drought impacts on the carbon and nitrogen cycle, which are fundamental to assessing drought impacts on ecosystems.

  10. MAESPA: a model to study interactions between water limitation, environmental drivers and vegetation function at tree and stand levels, with an example application to [CO2] × drought interactions

    Directory of Open Access Journals (Sweden)

    B. E. Medlyn

    2012-07-01

    Full Text Available Process-based models (PBMs of vegetation function can be used to interpret and integrate experimental results. Water limitation to plant carbon uptake is a highly uncertain process in the context of environmental change, and many experiments have been carried out that study drought limitations to vegetation function at spatial scales from seedlings to entire canopies. What is lacking in the synthesis of these experiments is a quantitative tool incorporating a detailed mechanistic representation of the water balance that can be used to integrate and analyse experimental results at scales of both the whole-plant and the forest canopy. To fill this gap, we developed an individual tree-based model (MAESPA, largely based on combining the well-known MAESTRA and SPA ecosystem models. The model includes a hydraulically-based model of stomatal conductance, root water uptake routines, drainage, infiltration, runoff and canopy interception, as well as detailed radiation interception and leaf physiology routines from the MAESTRA model. The model can be applied both to single plants of arbitrary size and shape, as well as stands of trees. The utility of this model is demonstrated by studying the interaction between elevated [CO2] (eCa and drought. Based on theory, this interaction is generally expected to be positive, so that plants growing in eCa should be less susceptible to drought. Experimental results, however, are varied. We apply the model to a previously published experiment on droughted cherry, and show that changes in plant parameters due to long-term growth at eCa (acclimation may strongly affect the outcome of Ca × drought experiments. We discuss potential applications of MAESPA and some of the key uncertainties in process representation.

  11. MAESPA: a model to study interactions between water limitation, environmental drivers and vegetation function at tree and stand levels, with an example application to [CO2] × drought interactions

    Directory of Open Access Journals (Sweden)

    B.E. Medlyn

    2012-02-01

    Full Text Available Process-based models (PBMs of vegetation function can be used to interpret and integrate experimental results. Water limitation to plant carbon uptake is a highly uncertain process in the context of environmental change, and many experiments have been carried out that study drought limitations to vegetation function at spatial scales from seedlings to entire canopies. What is lacking in the synthesis of these experiments is a quantitative tool that can be used to integrate and analyse experimental results at scales of both the whole-plant and the forest canopy, and that includes a detailed mechanistic representation of the water balance. To fill this gap, we developed an individual tree-based model (MAESPA, largely based on combining the well-known MAESTRA and SPA ecosystem models. The model includes a hydraulically-based model of stomatal conductance, root water uptake routines, drainage, infiltration, runoff and canopy interception, as well as detailed radiation interception and leaf physiology routines from the MAESTRA model. The model can be applied both to single plants of arbitrary size and shape, as well as stands of trees. The utility of this model is demonstrated by studying the interaction between elevated [CO2] (eCa and drought. Based on theory, this interaction is generally expected to be positive, so that plants growing in eCa should be less susceptible to drought. Experimental results, however, are varied. We apply the model to a previously published experiment on droughted cherry, and show that changes in plant parameters due to long-term growth at eCa (acclimation may strongly affect the outcome of Ca × drought experiments. We discuss potential applications of MAESPA and some of the key uncertainties in process representation.

  12. Trends and variability of droughts over the Indian monsoon region

    Directory of Open Access Journals (Sweden)

    Ganeshchandra Mallya

    2016-06-01

    Full Text Available Drought characteristics for the Indian monsoon region are analyzed using two different datasets and standard precipitation index (SPI, standardized precipitation-evapotranspiration index (SPEI, Gaussian mixture model-based drought index (GMM-DI, and hidden Markov model-based drought index (HMM-DI for the period 1901–2004. Drought trends and variability were analyzed for three epochs: 1901–1935, 1936–1971 and 1972–2004. Irrespective of the dataset and methodology used, the results indicate an increasing trend in drought severity and frequency during the recent decades (1972–2004. Droughts are becoming more regional and are showing a general shift to the agriculturally important coastal south-India, central Maharashtra, and Indo-Gangetic plains indicating higher food security and socioeconomic vulnerability in the region.

  13. Drought - A Global Assessment

    Science.gov (United States)

    Lackner, S.; Barnwal, P.; von der Goltz, J.

    2013-12-01

    We investigate the lasting effects of early childhood exposure to drought on economic and health outcomes in a large multi-country dataset. By pooling all Demographic and Health Survey rounds for which household geocodes are available, we obtain an individual-level dataset covering 47 developing countries. Among other impact measures, we collect infant and child mortality data from 3.3m live births and data on stunting and wasting for 1.2m individuals, along with data on education, employment, wealth, marriage and childbearing later in life for similarly large numbers of respondents. Birth years vary from 1893 to 2012. We seek to improve upon existing work on the socio-economic impact of drought in a number of ways. First, we introduce from the hydrological literature a drought measure, the Standardized Precipitation Index (SPI), that has been shown to closely proxy the Palmer drought index, but has far less demanding data requirements, and can be obtained globally and for long time periods. We estimate the SPI for 110 years on a global 0.5° grid, which allows us to assign drought histories to the geocoded individual data. Additionally, we leverage our large sample size to explicitly investigate both how drought impacts have changed over time as adaptation occurred at a varying pace in different locations, and the role of the regional extent of drought in determining impacts.

  14. COMPETITIVE INTELLIGENCE: SYSTEMIC MODEL PROPOSAL FOR ORGANIZATIONAL CHANGE FOR HOSPITALS IN SOUTHERN BRAZIL

    Directory of Open Access Journals (Sweden)

    Marcelo Jorge, Fernandez

    2011-01-01

    Full Text Available The success of an organization depends increasingly on its business strategy. A structural component of the strategy is the fittting between their primary activities and support activities. And as in industry, in a hospital, a new strategy to be implemented in general involves reviewing business processes or introduce new ways to run the operations of the company. However, organizations that have problems of alienation between the business strategy with its Information Technology infrastructure will have difficulties to implement a systemic model of the competitive intelligence process. It is believed that the private hospital sector has problems of synchronization between the business strategy with information technology infrastructure. Therefore, one can question: A systemic model of Competitive Intelligence for the private hospital sector can be a conceptual model of the change process, liable to be implemented in this type of organization? The main objective of this research is to propose a systemic model of Competitive Intelligence process version 2 in private hospitals in the southern region of Brazil.

  15. 基于SWAT模型的清江流域中上游旱灾监测%Drought monitoring of upper and middle reaches of Qingjiang Basin based on SWAT model

    Institute of Scientific and Technical Information of China (English)

    孙丽; 陈曦炜; 裴志远

    2014-01-01

    In recent years droughts occurred frequently in western, southwestern remote mountainous areas of China, affecting the local agricultural production and farmers' life. Drought monitoring and prediction is one of the main tasks of crop condition monitoring. Remote sensing data and ground survey data are used to monitor drought in current crop condition monitoring system, while high-resolution Remote sensing data and enough ground survey data for effective monitoring are often unable to access timely in those remote mountainous areas due to complex topography and broken plots. The aim of the study was to develop drought monitoring method to meet the complex terrain area and then to provide reliable scientific information to guide agricultural production. Crop water deficit index (CWDI) as an index characterizing agricultural drought has been widely used, which includes parameters of potential evapotranspiration (PET) and precipitation. Soil and water assessment tool (SWAT) as a distributed hydrological model with strong mechanism has been used to simulate crop’s potential evapotranspiration in those areas with complex topography. Those tools provide a feasible way of this study. The upper and middle reaches of Qingjiang River Basin, as the study area, from which drought conditions were monitored by the combination of CWDI and SWAT. Land use/cover data, soil data, topography data, meteorology data and hydrological data from 2003 to 2005 and 2007 to 2010 were used for calibration and validation of SWAT model. The PET simulated by SWAT had a high correlation fit with the PET calculated with meteorological data. Comparison of the statistical indexes included relative bias, root mean square error and multiple correlation coefficients. Standard precipitation index (SPI) was used for two times of drought monitoring tests to compare with the crop water deficit index (CWDI) based on the SWAT model. In July 2009, heavy drought happened in upper and middle reaches of

  16. Drought Management Strategies in Spain

    Directory of Open Access Journals (Sweden)

    Pilar Paneque

    2015-11-01

    Full Text Available The ongoing debate on water policies in Spain is characterised by a traditional paradigm, dominated by the intervention on hydrological systems through the construction and management of infrastructure, which is progressively being abandoned but is currently still strong while the emergence of new management approaches. Climate change and the Water Framework Directive (WFD are, in addition, the background to increasing challenges to traditional perspectives on drought, and important steps have been taken towards their replacement. This work analyzes the evolution of the normative structure and management models to identify recent shifts. The analysis is based on a fundamental conceptual change that places drought in the framework of risk, rather than that of crisis. I argue for the need to advance new prevention policies that can finally overcome productivist inertia and undertake essential tasks such as reallocating water flows, revising and controlling the water-concession system, and reinforcing and guaranteeing public participation.

  17. Spatio-temporal modelling of climate-sensitive disease risk: Towards an early warning system for dengue in Brazil

    Science.gov (United States)

    Lowe, Rachel; Bailey, Trevor C.; Stephenson, David B.; Graham, Richard J.; Coelho, Caio A. S.; Sá Carvalho, Marilia; Barcellos, Christovam

    2011-03-01

    This paper considers the potential for using seasonal climate forecasts in developing an early warning system for dengue fever epidemics in Brazil. In the first instance, a generalised linear model (GLM) is used to select climate and other covariates which are both readily available and prove significant in prediction of confirmed monthly dengue cases based on data collected across the whole of Brazil for the period January 2001 to December 2008 at the microregion level (typically consisting of one large city and several smaller municipalities). The covariates explored include temperature and precipitation data on a 2.5°×2.5° longitude-latitude grid with time lags relevant to dengue transmission, an El Niño Southern Oscillation index and other relevant socio-economic and environmental variables. A negative binomial model formulation is adopted in this model selection to allow for extra-Poisson variation (overdispersion) in the observed dengue counts caused by unknown/unobserved confounding factors and possible correlations in these effects in both time and space. Subsequently, the selected global model is refined in the context of the South East region of Brazil, where dengue predominates, by reverting to a Poisson framework and explicitly modelling the overdispersion through a combination of unstructured and spatio-temporal structured random effects. The resulting spatio-temporal hierarchical model (or GLMM—generalised linear mixed model) is implemented via a Bayesian framework using Markov Chain Monte Carlo (MCMC). Dengue predictions are found to be enhanced both spatially and temporally when using the GLMM and the Bayesian framework allows posterior predictive distributions for dengue cases to be derived, which can be useful for developing a dengue alert system. Using this model, we conclude that seasonal climate forecasts could have potential value in helping to predict dengue incidence months in advance of an epidemic in South East Brazil.

  18. A System Dynamics Model for Long-Term Planning of the Undergraduate Education in Brazil

    Science.gov (United States)

    Strauss, Luísa Mariele; Borenstein, Denis

    2015-01-01

    Higher education in Brazil has experienced a rapid expansion since the 1990s as a consequence of the government's pliability in launching new programs and educational institutions. This expansion was mainly driven by the private sector. Despite this expansion, Brazil has not yet achieved the enrollment goal expected in the National Education Plan…

  19. Spatial modeling using mixed models: an ecologic study of visceral leishmaniasis in Teresina, Piauí State, Brazil

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    Werneck Guilherme L.

    2002-01-01

    Full Text Available Most ecologic studies use geographical areas as units of observation. Because data from areas close to one another tend to be more alike than those from distant areas, estimation of effect size and confidence intervals should consider spatial autocorrelation of measurements. In this report we demonstrate a method for modeling spatial autocorrelation within a mixed model framework, using data on environmental and socioeconomic determinants of the incidence of visceral leishmaniasis (VL in the city of Teresina, Piauí, Brazil. A model with a spherical covariance structure indicated significant spatial autocorrelation in the data and yielded a better fit than one assuming independent observations. While both models showed a positive association between VL incidence and residence in a favela (slum or in areas with green vegetation, values for the fixed effects and standard errors differed substantially between the models. Exploration of the data's spatial correlation structure through the semivariogram should precede the use of these models. Our findings support the hypothesis of spatial dependence of VL rates and indicate that it might be useful to model spatial correlation in order to obtain more accurate point and standard error estimates.

  20. Spatial modeling using mixed models: an ecologic study of visceral leishmaniasis in Teresina, Piauí State, Brazil.

    Science.gov (United States)

    Werneck, Guilherme L; Maguire, James H

    2002-01-01

    Most ecologic studies use geographical areas as units of observation. Because data from areas close to one another tend to be more alike than those from distant areas, estimation of effect size and confidence intervals should consider spatial autocorrelation of measurements. In this report we demonstrate a method for modeling spatial autocorrelation within a mixed model framework, using data on environmental and socioeconomic determinants of the incidence of visceral leishmaniasis (VL) in the city of Teresina, Piauí, Brazil. A model with a spherical covariance structure indicated significant spatial autocorrelation in the data and yielded a better fit than one assuming independent observations. While both models showed a positive association between VL incidence and residence in a favela (slum) or in areas with green vegetation, values for the fixed effects and standard errors differed substantially between the models. Exploration of the data's spatial correlation structure through the semivariogram should precede the use of these models. Our findings support the hypothesis of spatial dependence of VL rates and indicate that it might be useful to model spatial correlation in order to obtain more accurate point and standard error estimates. PMID:12048589

  1. AquaCrop 模型在农业旱灾损失评估中的应用%Application of AquaCrop model in evaluation of agricultural drought losses

    Institute of Scientific and Technical Information of China (English)

    常文娟; 梁忠民

    2014-01-01

    利用作物生长机理模型---AquaCrop 模型,建立作物生长环境要素(气象、土壤水分等)与产量之间的定量关系,以此构建农业旱灾损失定量评估模型,并对云南省曲靖市沾益县一季中稻的旱灾损失进行了实例计算。结果表明, AquaCrop 模型能够客观地评估农业因旱损失,为旱灾风险分析计算提供灾损数据支撑。%T he AquaCrop model, based on t he mechanism of crop growth process, was introduced to develop the quantitative rela-tionship betw een crop environmental factors( w eather, soil moisture, etc) and crop yields, and t hen to construct a quantitat ive e-valuation model of the agricultural drought losses. The model w as applied to calculate the agricultural drought losses of season rice in Zhanyi County of Qujing City in Yunnan Province. The results showed that the AquaCrop model can assess the agricul-tural drought losses objectively and provide data support for drought risk analysis.

  2. Comparison between global solar radiation models in Aquidauana, “Alto Pantanal” region, Brazil

    Directory of Open Access Journals (Sweden)

    Gabriel Queiroz de Oliveira

    2014-09-01

    Full Text Available Solar radiation is a meteorological component of great importance to soil-plant-atmosphere processes, and the majority of weather stations do not register this component since they do not have the equipment for its quantification. The objective of this study was to evaluate the efficiency of models to estimate solar radiation for the annual, rainy and dry periods in Aquidauana “Alto Pantanal” region of Mato Grosso do Sul, Brazil. This study was conducted using meteorological data obtained from January 2008 to December 201. The automatic meteorological station was located in Aquidauana, and belongs to the network of the Instituto Nacional de Meteorologia (INMET. The data collected included maximum and minimum temperatures, and solar radiation. The Annandale, Bristow-Campbell, Hargreaves-Samani and Weiss empirical models were evaluated, and all were compared with the solar radiation value measured by the meteorological station. In Aquidauana, the Alto Pantanal region of Mato Grosso do Sul, regardless of the time of year, the Bristow-Campbell model is recommended to estimate solar radiation.

  3. Modelling of food intake in Brazil and Germany: Examining the effects of self-construals.

    Science.gov (United States)

    Hirata, Elizabeth; Kühnen, Ulrich; Hermans, Roel C J; Lippke, Sonia

    2015-12-01

    The current research focused on the influence of informational eating norms on people's food intake, and examined whether this influence was moderated by participants' self-construal levels. In two experiments, a two (intake norm manipulation: low vs. high) by two (self-construal manipulation: interdependent versus independent) between-participant factorial design was used. The studies were conducted in Brazil (Experiment 1) and in Germany (Experiment 2) as participants' self-construal levels differ between these countries. In Experiment 1, results indicated that participants exposed to a high-intake norm ate more than participants exposed to a low-intake norm. However, self-construal was not found to moderate the influence of food intake norms on participants' intake. In Experiment 2, replicating the results of Experiment 1, exposure to a high-intake norm increased participants' food intake, but self-construals again did not moderate modelling effects on food intake. Although differences in individuals' self-construal were found between both countries, they did not affect the magnitude of modelling effects on eating. Our studies provide evidence for cross-cultural similarity in the extent to which Brazilian and German female young adults are vulnerable to modelling effects on food intake, independent on their self-construal.

  4. Modelling of food intake in Brazil and Germany: Examining the effects of self-construals.

    Science.gov (United States)

    Hirata, Elizabeth; Kühnen, Ulrich; Hermans, Roel C J; Lippke, Sonia

    2015-12-01

    The current research focused on the influence of informational eating norms on people's food intake, and examined whether this influence was moderated by participants' self-construal levels. In two experiments, a two (intake norm manipulation: low vs. high) by two (self-construal manipulation: interdependent versus independent) between-participant factorial design was used. The studies were conducted in Brazil (Experiment 1) and in Germany (Experiment 2) as participants' self-construal levels differ between these countries. In Experiment 1, results indicated that participants exposed to a high-intake norm ate more than participants exposed to a low-intake norm. However, self-construal was not found to moderate the influence of food intake norms on participants' intake. In Experiment 2, replicating the results of Experiment 1, exposure to a high-intake norm increased participants' food intake, but self-construals again did not moderate modelling effects on food intake. Although differences in individuals' self-construal were found between both countries, they did not affect the magnitude of modelling effects on eating. Our studies provide evidence for cross-cultural similarity in the extent to which Brazilian and German female young adults are vulnerable to modelling effects on food intake, independent on their self-construal. PMID:26348265

  5. Exploration of drought evolution using numerical simulations over the Xijiang (West River) basin in South China

    Science.gov (United States)

    Niu, Jun; Chen, Ji; Sun, Liqun

    2015-07-01

    The knowledge of drought evolution characteristics may aid the decision making process in mitigating drought impacts. This study uses a macro-scale hydrological model, Variable Infiltration Capacity (VIC) model, to simulate terrestrial hydrological processes over the Xijiang (West River) basin in South China. Three drought indices, namely standardized precipitation index (SPI), standardized runoff index (SRI), and soil moisture anomaly index (SMAI), are employed to examine the spatio-temporal and evolution features of drought events. SPI, SRI and SMAI represent meteorological drought, hydrological drought and agricultural drought, respectively. The results reveal that the drought severity depicted by SPI and SRI is similar with increasing timescales; SRI is close to that of SPI in the wet season for the Liu River basin as the high-frequency precipitation is conserved more by runoff; the time lags appear between SPI and SRI due to the delay response of runoff to precipitation variability for the You River basin. The case study in 2010 spring drought further shows that the spatio-temporal evolutions are modulated by the basin-scale topography. There is more consistency between meteorological and hydrological droughts for the fan-like basin with a converged river network. For the west area of the Xijiang basin with the high elevation, the hydrological drought severity is less than meteorological drought during the developing stage. The recovery of hydrological and agricultural droughts is slower than that of meteorological drought for basins with a longer mainstream.

  6. Institutional adaptation to drought: the case of Fars Agricultural Organization.

    Science.gov (United States)

    Keshavarz, Marzieh; Karami, Ezatollah

    2013-09-30

    Recurrent droughts in arid and semi-arid regions are already rendering agricultural production, mainstay of subsistence livelihoods, uncertain. In order to mitigate the impact of drought, agricultural organizations must increase their capacity to adapt. Institutional adaptation refers to the creation of an effective, long-term government institution or set of institutions in charge of planning and policy, and its capacity to develop, revise, and execute drought policies. Using the Fars Agricultural Organization in Iran, as a case study, this paper explores the institutional capacities and capabilities, necessary to adapt to the drought conditions. The STAIR model was used as a conceptual tool, and the Bayesian network and Partial Least Squares (PLS) path modeling was applied to explain the mechanisms by which organizational capacities influence drought management. A survey of 309 randomly selected managers and specialists indicated serious weaknesses in the ability of the organization to apply adaptation strategies effectively. Analysis of the causal models illustrated that organizational culture and resources and infrastructure significantly influenced drought management performance. Moreover, managers and specialists perceived human resources and strategy, goals, and action plan, respectively, as the main drivers of institutional adaptation to drought conditions. Recommendations and implications for drought management policy are offered to increase organizational adaptation to drought and reduce the subsequent sufferings.

  7. Variation and Trends of Regional Drought in China

    Science.gov (United States)

    Wu, Z.; Lu, G.; Wen, L.; Kuang, Y.

    2011-12-01

    Drought is a long-lasting and widespread natural disaster that casts shadow on socioeconomic development and ecological environment. A comprehensive study of drought holds the key to achieve effective disaster prevention and mitigation. Variation and trends of regional drought in China are analyzed using a soil moisture based drought index derived from a 59-year (1951-2009) simulation of the terrestrial hydrologic cycle. The Variable Infiltration Capacity (VIC) land surface macro-scale hydrology model is used for the soil moisture simulation and is driven by observed air temperature and precipitation. The simulated soil moisture values are used to calculate the Soil Moisture Anomaly Percentage Index (SMAPI) as an indicator for measuring the severity of agricultural and hydrological droughts on a global basis. A SMAPI-based drought identification procedure is developed for practical uses in the identification of both grid point and regional drought events. As a result, a total of 325 regional drought events varying in time and strength are identified from China's nine drought study regions during 1951-2009. These drought events can thus be assessed quantitatively at different spatial and temporal scales. The result shows that on average, up to 30% of the total area of China is prone to drought over the past 59 years. There exist two regional dry centers. The first center is located in the area partially covered by two drought study regions North and Northwest, which extends to the southeastern portion of Inner Mongolia and the southwest part of Northeast. The second one is found in the central to southern portion of the drought study region South. Regionally, Inner Mongolia was often hit by successive droughts during autumn-winter months. However, such a characteristic is likely to undergo change in the future as more and more successive droughts observed in all four seasons in recent 10 year. Two regions (Northeast and North) are prone to multi-year drought

  8. Palmer Drought Severity Index

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — PDSI from the Dai dataset. The Palmer Drought Severity Index (PDSI) is devised by Palmer (1965) to represent the severity of dry and wet spells over the U.S. based...

  9. A Bayesian Network-Based Probabilistic Framework for Drought Forecasting and Outlook

    Directory of Open Access Journals (Sweden)

    Ji Yae Shin

    2016-01-01

    Full Text Available Reliable drought forecasting is necessary to develop mitigation plans to cope with severe drought. This study developed a probabilistic scheme for drought forecasting and outlook combined with quantification of the prediction uncertainties. The Bayesian network was mainly employed as a statistical scheme for probabilistic forecasting that can represent the cause-effect relationships between the variables. The structure of the Bayesian network-based drought forecasting (BNDF model was designed using the past, current, and forecasted drought condition. In this study, the drought conditions were represented by the standardized precipitation index (SPI. The accuracy of forecasted SPIs was assessed by comparing the observed SPIs and confidence intervals (CIs, exhibiting the associated uncertainty. Then, this study suggested the drought outlook framework based on probabilistic drought forecasting results. The overall results provided sufficient agreement between the observed and forecasted drought conditions in the outlook framework.

  10. Drought Policy: A State-contingent View

    OpenAIRE

    Quiggin, John; Chambers, Robert G.

    2003-01-01

    The standard approach to modelling production under uncertainty has relied on the concept of the stochastic production. In this paper, it is argued that a state-contingent production model is more flexible and realistic. The model is applied to the problem of drought policy.

  11. Long term context for recent drought in northwestern Africa

    Science.gov (United States)

    Touchan, Ramzi; Anchukaitis, Kevin J.; Meko, David M.; Attalah, Said; Baisan, Christopher; Aloui, Ali

    2008-07-01

    Anthropogenic climate change is projected to exacerbate midlatitude aridity. Here, we analyze newly developed multi-century tree-ring records for a long-term perspective on drought in Tunisia and Algeria. We use a new set of 13 Cedrus atlantica and Pinus halepensis chronologies with a strong signal for warm-season drought (May-August) to generate a robust, well-validated reconstruction of the Palmer Drought Severity Index (PDSI) for the period AD 1456-2002. Key features of the reconstruction reveal the magnitude of pre-instrumental droughts from the historic record. Remarkably, the most recent drought (1999-2002) appears to be the worst since at least the middle of the 15th century. This drought is consistent with the early signature of a transition to more arid midlatitude conditions, as projected by general circulation models.

  12. Root Niche Separation Can Explain Avoidance of Seasonal Drought Stress and Vulnerability of Overstory Trees to Extended Drought

    Science.gov (United States)

    Ivanov, V. Y.; Hutyra, L.; Wofsy, S. C.; Munger, J. W.; Saleska, S. R.; Oliveira, R. C.; Camargo, P. B.

    2011-12-01

    Large areas of Amazonian evergreen forests experience seasonal droughts extending for three or more months, and show maximum rates of photosynthesis and evapotranspiration during dry intervals. This apparent resilience is belied by disproportionate mortality of the large trees in manipulations that reduce wet season rainfall, occurring after 2-3 years of treatment. The goal of this study is to characterize the mechanisms that produce these contrasting ecosystem responses. A mechanistic vegetation-hydrology model is developed to test the roles of deep roots and of soil capillary flux to provide water to the forest during the dry season. Also examined is the importance of ``root niche separation,'' in which roots of overstory trees extend to depth, where during the dry season they use water stored from wet season precipitation, while roots of understory trees are concentrated in shallow layers that access dry season precipitation directly. Observational data on canopy phenology, energy fluxes, soil moisture, and soil and root structure from the Tapajos National Forest, Brazil, provided comprehensive observational constraints on the model. Results strongly suggest that deep roots with root niche separation adaptations explain both the observed resilience during seasonal drought and the vulnerability of canopy-dominant trees to extended deficits of wet season rainfall. These mechanisms appear to provide an adaptive strategy that enhances productivity of the largest trees in the face of their disproportionate heat loads and water demand in the dry season. A sensitivity analysis exploring how wet season rainfall affects the stability of the rainforest system is presented. The model can be used to quantitatively predict ecosystem water balances and explore ecosystem tipping points under future climate change.

  13. Drought, Water Scarcity and Climate Change

    Science.gov (United States)

    van Lanen, H. A. J.; Tallaksen, L. M.; Stahl, K.; van Loon, A. F.; van Huijgevoort, M. H. J.; Corzo Perez, G. A.; Wanders, N.

    2012-04-01

    A recent multi-model analysis using global hydrological model shows a decline of future available water resources by 10-50% in substantial parts of southern, western and central Europe. This implies that water scarcity (long-term unsustainable use of water resources) likely will increase. Additionally, there is some confidence that in southern and central Europe drought will intensify in the 21st century, hence impacts of drought will become more severe. The higher risk for water scarcity and drought calls for an intensified debate on the adaptation of land and water management in Europe. The debate requires a distinction to be made between drought and water scarcity because underlying processes are fundamentally different, which requires management to identify different measures. A case study will be presented demonstrating on how to distinguish between drought and water scarcity. The impacts of drought usually exacerbate scarcity, which makes it necessary to have a comprehensive understanding of future drought risk to identify promising management options. Usually models are applied to project future changes in drought characteristics. The EU project WATCH provided gridded time series (0.5 degree) of a suite of global hydrological models forced by three GCMs. Several characteristics (e.g. change in areas with zero runoff, frequency, durations) of future drought have been derived and will be presented for the globe and Europe in particular. Model performance was evaluated by an intercomparison exercise, assuming that the more the models agree, the more likely they are providing a good representation of reality. Key drought characteristics (e.g. frequency, duration) have been mapped at the global scale and the results will be presented for the range of models included. The large-scale models were also assessed by comparing against an extensive dataset of streamflow observations in Europe. Modelled trends in annual, monthly and low flow simulated with large

  14. Classification of Meteorological Drought

    Institute of Scientific and Technical Information of China (English)

    Zhang Qiang; Zou Xukai; Xiao Fengjin; Lu Houquan; Liu Haibo; Zhu Changhan; An Shunqing

    2011-01-01

    Background The national standard of the Classification of Meteorological Drought (GB/T 20481-2006) was developed by the National Climate Center in cooperation with Chinese Academy of Meteorological Sciences,National Meteorological Centre and Department of Forecasting and Disaster Mitigation under the China Meteorological Administration (CMA),and was formally released and implemented in November 2006.In 2008,this Standard won the second prize of the China Standard Innovation and Contribution Awards issued by SAC.Developed through independent innovation,it is the first national standard published to monitor meteorological drought disaster and the first standard in China and around the world specifying the classification of drought.Since its release in 2006,the national standard of Classification of Meteorological Drought has been used by CMA as the operational index to monitor and drought assess,and gradually used by provincial meteorological sureaus,and applied to the drought early warning release standard in the Methods of Release and Propagation of Meteorological Disaster Early Warning Signal.

  15. Simultaneous Control of Phenanthrene and Drought by Dual Exposure System

    DEFF Research Database (Denmark)

    Schmidt, Stine N.; Holmstrup, Martin; Damgaard, Christian;

    2014-01-01

    and independent control of chemical and drought exposure in bioassays with terrestrial organisms: Passive dosing from silicone controlled the chemical activity of phenanthrene (chemical stress), while saline solutions controlled the water activity (drought stress) in the closed exposure system. The dual exposure...... system was then applied in a full factorial experiment with seven exposure levels (72), which aimed at determining the combined effects of phenanthrene and drought on the survival of the terrestrial springtail Folsomia candida after 7 d exposure. Fitting an "independent action" model to the complete data...... set revealed statistically significant synergy between phenanthrene and drought (p

  16. A global evaluation of streamflow drought characteristics

    Directory of Open Access Journals (Sweden)

    A. K. Fleig

    2006-01-01

    Full Text Available How drought is characterised depends on the purpose and region of the study and the available data. In case of regional applications or global comparison a standardisation of the methodology to characterise drought is preferable. In this study the threshold level method in combination with three common pooling procedures is applied to daily streamflow series from a wide range of hydrological regimes. Drought deficit characteristics, such as drought duration and deficit volume, are derived, and the methods are evaluated for their applicability for regional studies. Three different pooling procedures are evaluated: the moving-average procedure (MA-procedure, the inter-event time method (IT-method, and the sequent peak algorithm (SPA. The MA-procedure proved to be a flexible approach for the different series, and its parameter, the averaging interval, can easily be optimised for each stream. However, it modifies the discharge series and might introduce dependency between drought events. For the IT-method it is more difficult to find an optimal value for its parameter, the length of the excess period, in particular for flashy streams. The SPA can only be recommended as pooling procedure for the selection of annual maximum series of deficit characteristics and for very low threshold levels to ensure that events occurring shortly after major events are recognized. Furthermore, a frequency analysis of deficit volume and duration is conducted based on partial duration series of drought events. According to extreme value theory, excesses over a certain limit are Generalized Pareto (GP distributed. It was found that this model indeed performed better than or equally to other distribution models. In general, the GP-model could be used for streams of all regime types. However, for intermittent streams, zero-flow periods should be treated as censored data. For catchments with frost during the winter season, summer and winter droughts have to be analysed

  17. Bivariate Drought Analysis Using Streamflow Reconstruction with Tree Ring Indices in the Sacramento Basin, California, USA

    Directory of Open Access Journals (Sweden)

    Jaewon Kwak

    2016-03-01

    Full Text Available Long-term streamflow data are vital for analysis of hydrological droughts. Using an artificial neural network (ANN model and nine tree-ring indices, this study reconstructed the annual streamflow of the Sacramento River for the period from 1560 to 1871. Using the reconstructed streamflow data, the copula method was used for bivariate drought analysis, deriving a hydrological drought return period plot for the Sacramento River basin. Results showed strong correlation among drought characteristics, and the drought with a 20-year return period (17.2 million acre-feet (MAF per year in the Sacramento River basin could be considered a critical level of drought for water shortages.

  18. Is drought helping or killing dengue? Investigation of spatiotemporal relationship between dengue fever and drought

    Science.gov (United States)

    Lee, Chieh-Han; Yu, Hwa-Lung

    2015-04-01

    Dengue Fever is a vector-borne disease that is transmitted between human and mosquitos in tropical and sub-tropical regions. Previous studies have found significant relationship between the epidemic of dengue cases and climate variables, especially temperature and precipitation. Besides, the natural phenomena (e.g., drought) are considered that significantly drop the number of dengue cases by killing vector's breeding environment. However, in Kaohsiung City, Taiwan, there are evidences that the temporal pattern of dengue is correlated to drought events. Kaohsiung City experienced two main dengue outbreaks in 2002 and 2014 that both years were confirmed with serious drought. Especially in 2014, Kaohsiung City was suffered from extremely dengue outbreak in 2014 that reported the highest number of dengue cases in the history. This study constructs the spatiotemporal model of dengue incidences and index of drought events (Standardized Precipitation Index, SPI) based on the distributed lag nonlinear model (DLNM). Other meteorological measures are also included in the analysis.

  19. Analysis and Forecasting of Drought by Developing a Fuzzy-Based Hybrid Index in Iran

    OpenAIRE

    Moghaddasi, Reza; Eghbali, Alireza; Lakhaye Rizi, Parisa

    2014-01-01

    Drought is the most important and destructive climate phenomenon which is usually of importance in a regional scale. Therefore, this study offers a fuzzy-based hybrid index in order to analyze the regional drought in Abadan and khoramshahr, Khuzestan, Iran. Influencing all aspects of human activity, drought does not have a comprehensive definition and an appropriate and general index to explore it. Consequently, in order to develop a model to evaluate and analyze drought, the fuzzy model has...

  20. Drought in Northeast Brazil—past, present, and future

    Science.gov (United States)

    Marengo, Jose A.; Torres, Roger Rodrigues; Alves, Lincoln Muniz

    2016-06-01

    This study provides an overview of the drought situation in Northeast Brazil for the past, present, and future. Droughts affect more people than any other natural hazard owing to their large scale and long-lasting nature. They are recurrent in the region and while some measures have been taken by the governments to mitigate their impacts, there is still a perception that residents, mainly in rural areas, are not yet adapted to these hazards. The drought affecting the Northeast from 2012 to 2015, however, has had an intensity and impact not seen in several decades and has already destroyed large swaths of cropland, affecting hundreds of cities and towns across the region, and leaving ranchers struggling to feed and water cattle. Future climate projections for the area show large temperature increases and rainfall reductions, which, together with a tendency for longer periods with consecutive dry days, suggest the occurrence of more frequent/intense dry spells and droughts and a tendency toward aridification in the region. All these conditions lead to an increase in evaporation from reservoirs and lakes, affecting irrigation and agriculture as well as key water uses including hydropower and industry, and thus, the welfare of the residents. Integrating drought monitoring and seasonal forecasting provides efficient means of assessing impacts of climate variability and change, identifying vulnerabilities, and allowing for better adaptation measures not only for medium- and long-term climate change but also for extremes of the interannual climate variability, particularly droughts.

  1. Estimating the water needed to end the drought or reduce the drought severity in the Carpathian region

    OpenAIRE

    T. Antofie; Naumann, G.; J. Spinoni; Vogt, J

    2015-01-01

    A drought severity climatology for the Carpathian region has been produced using the self-calibrating Palmer Drought Severity Index (Sc-PDSI) for the period 1961–2010. Using the Sc-PDSI and the assumptions of the Palmer drought model (PDM) the precipitation required for drought termination (when Sc-PDSI reaches −0.5) and amelioration (when Sc-PDSI reaches −2.0) are computed for periods of 1, 3, and 6 months. We discuss the reduction of the uncertainty in the dete...

  2. ABACC - Brazil-Argentina Agency for Accounting and Control of Nuclear Materials, a model of integration and transparence

    International Nuclear Information System (INIS)

    Argentina and Brazil began its activities in the nuclear area about the same time, in the 50 century past. The existence of an international nuclear nonproliferation treaty-TNP-seen by Brazil and Argentina as discriminatory and prejudicial to the interests of the countries without nuclear weapons, led to the need for a common system of control of nuclear material between the two countries to somehow provide assurances to the international community of the exclusively peaceful purpose of its nuclear programs. The creation of a common system, assured the establishment of uniform procedures to implement safeguards in Argentina and Brazil, so the same requirements and safeguards procedures took effect in both countries, and the operators of nuclear facilities began to follow the same rules of control of nuclear materials and subjected to the same type of verification and control. On July 18, 1991, the Bilateral Agreement for the Exclusively Peaceful Use of Nuclear Energy created a binational body, the Argentina-Brazil Agency for Accounting and Control of Nuclear Materials-ABACC-to implement the so-called Common System of Accounting and Control of Nuclear materials - SCCC. The deal provided, permanently, a clear commitment to use exclusively for peaceful purposes all material and nuclear facilities under the jurisdiction or control of the two countries. The Quadripartite Agreement, signed in December of that year, between the two countries, ABACC and IAEA completed the legal framework for the implementation of comprehensive safeguards system. The 'model ABACC' now represents a paradigmatic framework in the long process of economic, political, technological and cultural integration of the two countries. Argentina and Brazil were able to establish a guarantee system that is unique in the world today and that consolidated and matured over more than twenty years, has earned the respect of the international community

  3. Assessing water resource system vulnerability to unprecedented hydrological drought using copulas to characterize drought duration and deficit

    Science.gov (United States)

    Borgomeo, Edoardo; Pflug, Georg; Hall, Jim W.; Hochrainer-Stigler, Stefan

    2015-11-01

    Global climate models suggest an increase in evapotranspiration, changing storm tracks, and moisture delivery in many parts of the world, which are likely to cause more prolonged and severe drought, yet the weakness of climate models in modeling persistence of hydroclimatic variables and the uncertainties associated with regional climate projections mean that impact assessments based on climate model output may underestimate the risk of multiyear droughts. In this paper, we propose a vulnerability-based approach to test water resource system response to drought. We generate a large number of synthetic streamflow series with different drought durations and deficits and use them as input to a water resource system model. Marginal distributions of the streamflow for each month are generated by bootstrapping the historical data, while the joint probability distributions of consecutive months are constructed using a copula-based method. Droughts with longer durations and larger deficits than the observed record are generated by perturbing the copula parameter and by adopting an importance sampling strategy for low flows. In this way, potential climate-induced changes in monthly hydrological persistence are factored into the vulnerability analysis. The method is applied to the London water system (England) to investigate under which drought conditions severe water use restrictions would need to be imposed. Results indicate that the water system is vulnerable to drought conditions outside the range of historical events. The vulnerability assessment results were coupled with climate model information to compare alternative water management options with respect to their vulnerability to increasingly long and severe drought.

  4. Possible Future Climate Change Impacts on the Hydrological Drought Events in the Weihe River Basin, China

    Directory of Open Access Journals (Sweden)

    Fei Yuan

    2016-01-01

    Full Text Available Quantitative evaluation of future climate change impacts on hydrological drought characteristics is one of important measures for implementing sustainable water resources management and effective disaster mitigation in drought-prone regions under the changing environment. In this study, a modeling system for projecting the potential future climate change impacts on hydrological droughts in the Weihe River basin (WRB in North China is presented. This system consists of a large-scale hydrological model driven by climate outputs from three climate models (CMs for future streamflow projections, a probabilistic model for univariate drought assessment, and a copula-based bivariate model for joint drought frequency analysis under historical and future climates. With the observed historical climate data as the inputs, the Variable Infiltration Capacity hydrological model projects an overall runoff reduction in the WRB under the Intergovernmental Panel on Climate Change A1B scenario. The univariate drought assessment found that although fewer hydrological drought events would occur under A1B scenario, drought duration and severity tend to increase remarkably. Moreover, the bivariate drought assessment reveals that future droughts in the same return period as the baseline droughts would become more serious. With these trends in the future, the hydrological drought situation in the WRB would be further deteriorated.

  5. Wound Healing and Anti-Inflammatory Effect in Animal Models of Calendula officinalis L. Growing in Brazil

    OpenAIRE

    Leila Maria Leal Parente; Ruy de Souza Lino Júnior; Leonice Manrique Faustino Tresvenzol; Marina Clare Vinaud; José Realino de Paula; Neusa Margarida Paulo

    2012-01-01

    Calendula officinalis is an annual herb from Mediterranean origin which is popularly used in wound healing and as an anti-inflammatory agent. In this study, the ethanolic extract, the dichloromethane, and hexanic fractions of the flowers from plants growing in Brazil were produced. The angiogenic activity of the extract and fractions was evaluated through the chorioallantoic membrane and cutaneous wounds in rat models. The healing activity of the extract was evaluated by the same cutaneous wo...

  6. A synthesized drought monitoring model based on multi-source remote sensing data%基于多源遥感数据的综合干旱监测模型构建

    Institute of Scientific and Technical Information of China (English)

    杜灵通; 田庆久; 王磊; 黄彦; 南岭

    2014-01-01

    As global climate change become more complex, accurately monitoring the impact of drought on main grain producing areas in North China Plain has important guiding implication for regional agricultural production planning. The conventional remote sensing methods only monitor single drought response factors such as soil,vegetation. This method does not reflect the comprehensive information of drought. Based on the soil water stress, vegetation growth status and precipitation deficit in drought developing process, a synthesized drought monitoring model was developed using spatial data mining techniques and multi-source remote sensing data includingMODIS and TRMM. For assessing the accuracy of this drought monitoring model, a validation experiment was conducted in Shandong province. The results showed that the main drought events monitored by this model in recent years were consistent with observed droughts in Shandong province. The Synthesized Drought Index (SDI), a drought indicator produced by the model, not only includes agricultural drought informaion but also includes meteorological drought informaion. In the wheat growing period (March-May), the correlation coefficient of accumulated monthly SDI with crop yield as a standardized variable all were exceeding 0.7 (P<0.05) in Heze, Liaocheng and Dezhou, three main wheat producing cities of Shandong province. SDI was negatively correlated with drought affected crop area. The correlation coefficient of monthly SDI with drought affected crop area in wheat (March-May) and maize (July-September) growing period are between-0.67--0.85 and all passed significance test (P<0.01) except March (P<0.05). The SDI was also significantly correlated with meteorological drought index. In wheat and maize growing period, the correlation coefficients between monthly SDI and Standardized Precipitation Index (SPI) are between 0.44-0.67 and all correlation coefficients passed P<0.01 significance test except March. This work provides a new

  7. Biophysical modelling of intra-ring variations in tracheid features and wood density of Pinus pinaster trees exposed to seasonal droughts.

    Science.gov (United States)

    Wilkinson, Sarah; Ogée, Jérôme; Domec, Jean-Christophe; Rayment, Mark; Wingate, Lisa

    2015-03-01

    Process-based models that link seasonally varying environmental signals to morphological features within tree rings are essential tools to predict tree growth response and commercially important wood quality traits under future climate scenarios. This study evaluated model portrayal of radial growth and wood anatomy observations within a mature maritime pine (Pinus pinaster (L.) Aït.) stand exposed to seasonal droughts. Intra-annual variations in tracheid anatomy and wood density were identified through image analysis and X-ray densitometry on stem cores covering the growth period 1999-2010. A cambial growth model was integrated with modelled plant water status and sugar availability from the soil-plant-atmosphere transfer model MuSICA to generate estimates of cell number, cell volume, cell mass and wood density on a weekly time step. The model successfully predicted inter-annual variations in cell number, ring width and maximum wood density. The model was also able to predict the occurrence of special anatomical features such as intra-annual density fluctuations (IADFs) in growth rings. Since cell wall thickness remained surprisingly constant within and between growth rings, variations in wood density were primarily the result of variations in lumen diameter, both in the model and anatomical data. In the model, changes in plant water status were identified as the main driver of the IADFs through a direct effect on cell volume. The anatomy data also revealed that a trade-off existed between hydraulic safety and hydraulic efficiency. Although a simplified description of cambial physiology is presented, this integrated modelling approach shows potential value for identifying universal patterns of tree-ring growth and anatomical features over a broad climatic gradient. PMID:25769337

  8. Biophysical modelling of intra-ring variations in tracheid features and wood density of Pinus pinaster trees exposed to seasonal droughts.

    Science.gov (United States)

    Wilkinson, Sarah; Ogée, Jérôme; Domec, Jean-Christophe; Rayment, Mark; Wingate, Lisa

    2015-03-01

    Process-based models that link seasonally varying environmental signals to morphological features within tree rings are essential tools to predict tree growth response and commercially important wood quality traits under future climate scenarios. This study evaluated model portrayal of radial growth and wood anatomy observations within a mature maritime pine (Pinus pinaster (L.) Aït.) stand exposed to seasonal droughts. Intra-annual variations in tracheid anatomy and wood density were identified through image analysis and X-ray densitometry on stem cores covering the growth period 1999-2010. A cambial growth model was integrated with modelled plant water status and sugar availability from the soil-plant-atmosphere transfer model MuSICA to generate estimates of cell number, cell volume, cell mass and wood density on a weekly time step. The model successfully predicted inter-annual variations in cell number, ring width and maximum wood density. The model was also able to predict the occurrence of special anatomical features such as intra-annual density fluctuations (IADFs) in growth rings. Since cell wall thickness remained surprisingly constant within and between growth rings, variations in wood density were primarily the result of variations in lumen diameter, both in the model and anatomical data. In the model, changes in plant water status were identified as the main driver of the IADFs through a direct effect on cell volume. The anatomy data also revealed that a trade-off existed between hydraulic safety and hydraulic efficiency. Although a simplified description of cambial physiology is presented, this integrated modelling approach shows potential value for identifying universal patterns of tree-ring growth and anatomical features over a broad climatic gradient.

  9. Modeling HIV/AIDS Drug Price Determinants in Brazil: Is Generic Competition a Myth?

    OpenAIRE

    Constance Meiners; Luis Sagaon-Teyssier; Lia Hasenclever; Jean-Paul Moatti

    2011-01-01

    BACKGROUND: Brazil became the first developing country to guarantee free and universal access to HIV/AIDS treatment, with antiretroviral drugs (ARVs) being delivered to nearly 190,000 patients. The analysis of ARV price evolution and market dynamics in Brazil can help anticipate issues soon to afflict other developing countries, as the 2010 revision of the World Health Organization guidelines shifts demand towards more expensive treatments, and, at the same time, current evolution of internat...

  10. Rainwater harvesting in the challenge of droughts and climate change in semi-arid Brazil%巴西半干旱地区干旱和气候多变情况下的雨水收集

    Institute of Scientific and Technical Information of China (English)

    Johann Gnadlinger

    2014-01-01

    Some successful experiences of rainwater harvesting in Brazil’s semi-arid region are shown how rural communities are living during the severe drought from 2011 to 2013 using technologies of rainwater harvesting for the household in agriculture livestock raising and the environment.Starting from the positive experiences principles of living in the challenge of droughts and climate change are elaborated and summarized into different guidelines for sustainable livelihood and production access to water and sufficient land area rainwater harvesting to provide water security to households and communities preservation recovering and management of drought-resistant vegetation emphases on raising of small and medium sized livestock and water and forage storage appropriate crop selection and sustainable extraction processing and marketing of crop products capacity building of the people. These principles contribute to preparing a national policy on living in harmony with the semi-arid climate. Rainwater harvesting is an important part of a package of measures which enables a sustainable livelihood in such a difficult environment.%通过巴西半干旱地区的一些成功案例,介绍了当地农村社区在2011~2013年严重旱灾期间所采取的有效措施:对生活用水、农业用水和畜牧用水采取水资源管理技术;对土壤湿度和含水层采取诸如蓄水池、地下水坝等环境保护措施。根据这些经验,总结出旱灾和气候变化环境下的生活原则,并制定成可持续性生活生产的指导方针:获取足够的水资源和土地面积;利用雨水以保证家庭和社区的用水安全;种植、养护与管理抗旱植物;倡导对中小型家畜养殖的水和饲料储存;加强农作物品种甄选及其产品的可持续生产、加工和销售;重视居民的水资源保护思想和能力培养。这些原则为指导干旱气候条件下人与环境和谐相处提供了宝贵的经验。

  11. Deficit of sand in a sediment transport model favors coral reef development in Brazil

    Directory of Open Access Journals (Sweden)

    Abílio C.S.P. Bittencourt

    2008-03-01

    Full Text Available This paper shows that the location of the shoreface bank reefs along the northeastern and eastern coasts of Brazil, in a first order approximation, seem to be controlled by the deficit of sediment in the coastal system. The sediment transport pattern defined by a numerical modeling of wave refraction diagrams, representing circa 2000 km of the northeastern and eastern coasts of Brazil, permitted the regional-scale reproduction of several drift cells of net longshore sediment transport. Those drift cells can reasonably explain the coastal sections that present sediment surplus or sediment deficit, which correspond, respectively, to regions where there is deposition and erosion or little/no deposition of sand. The sediment deficit allows the exposure and maintenance of rocky substrates to be free of sediment, a favorable condition for the fixation and development of coral larvae.Este trabalho mostra que a localização dos recifes de coral ao longo dos litorais leste e nordeste do Brasil, em uma aproximação de primeira ordem, parece ser controlada pelo déficit de sedimentos no sistema costeiro. O padrão de transporte de sedimentos definido por modelagem numérica a partir de diagramas de refração de ondas, representando cerca de 2000 km dos litorais leste e nordeste do Brasil, permitiu a reprodução, em escala regional, de várias células de deriva litorânea efetiva de sedimentos. Essas células de deriva podem razoavelmente explicar os segmentos costeiros que representam superávit, ou deficit de sedimentos que correspondem, respectivamente, a regiões onde existe deposição e erosão ou pouca/nenhuma deposição de areia. O deficit de sedimentos propicia a exposição e manutenção de substratos rochosos livres de sedimento, uma condição favorável para a fixação e desenvolvimento das larvas de coral.

  12. Geographic Distribution of Chagas Disease Vectors in Brazil Based on Ecological Niche Modeling

    Directory of Open Access Journals (Sweden)

    Rodrigo Gurgel-Gonçalves

    2012-01-01

    Full Text Available Although Brazil was declared free from Chagas disease transmission by the domestic vector Triatoma infestans, human acute cases are still being registered based on transmission by native triatomine species. For a better understanding of transmission risk, the geographic distribution of Brazilian triatomines was analyzed. Sixteen out of 62 Brazilian species that both occur in >20 municipalities and present synanthropic tendencies were modeled based on their ecological niches. Panstrongylus geniculatus and P. megistus showed broad ecological ranges, but most of the species sort out by the biome in which they are distributed: Rhodnius pictipes and R. robustus in the Amazon; R. neglectus, Triatoma sordida, and T. costalimai in the Cerrado; R. nasutus, P. lutzi, T. brasiliensis, T. pseudomaculata, T. melanocephala, and T. petrocchiae in the Caatinga; T. rubrovaria in the southern pampas; T. tibiamaculata and T. vitticeps in the Atlantic Forest. Although most occurrences were recorded in open areas (Cerrado and Caatinga, our results show that all environmental conditions in the country are favorable to one or more of the species analyzed, such that almost nowhere is Chagas transmission risk negligible.

  13. Geologic conceptual model of the municipality of Sete Lagoas (MG, Brazil and the surroundings

    Directory of Open Access Journals (Sweden)

    PAULO GALVÃO

    2016-03-01

    Full Text Available ABSTRACT The study area is located in the state of Minas Gerais, Brazil, among the municipalities of Pedro Leopoldo, Matozinhos, and Sete Lagoas, with Velhas River as the eastern boundary. It is located in the São Francisco Craton, where carbonated argillo-arenaceous sediments are emplaced giving origin to the Bambuí Group, in the São Francisco Basin. Despite the geological knowledge previously developed, the region needs work on integration and detailing of such information. For this reason, the main objective was to contribute to the quality of the geologic cartography, the spatial distribution, and the structural framework geometry. Thus, geologic mapping, aerial photography interpretation, and evaluation of 270 lithologic well profiles were carried out. It was possible to establish a new geologic perspective of the region by obtaining the detailed geologic map of the municipality of Sete Lagoas, 14 geologic cross sections, and a geologic conceptual model. The study showed that the area is within a basin border, presenting a geometry conditioned by horst and graben system controlled by faulting. This structural feature displaced stratigraphic sequences positioning them side by side with lithologic sequences with different ages.

  14. Application of agrometeorological spectral model in rice area in southern Brazil

    Science.gov (United States)

    Leivas, Janice F.; de C. Teixeira, Antonio Heriberto; Andrade, Ricardo G.; de C. Victoria, Daniel; Bayma-Silva, Gustavo; Bolfe, Edson L.

    2015-10-01

    The southern region is responsible for 70% of rice production in Brazil. In this study, rice areas of Rio Grande do Sul were selected, using the land use classification, scale 1: 100,000, provided by Brazilian Institute of Geography and Statistics (IBGE). MODIS Images were used and meteorological data, available by National Institute of Meteorology (INMET). The period of analysis was crop season 2011/2012, October to March. To obtain evapotranspiration was applied agrometeorological-spectral model SAFER (Simple Algorithm For Retrieving Evapotranspiration). From the analysis of the results, on planting and cultivation period , the average evapotranspiration (ET) daily was 1.93 +/- 0.96 mm.day-1. In the vegetative development period of rice, the daily ET has achieved 4.94 mm.day-1, with average value 2,31+/- 0.97 mm.day-1. In the period of harvest, evapotranspiration daily average was 1.84 +/- 0.80 mm.day-1. From results obtained, the estimation of evapotranspiration from satellite images may assist in monitoring the culture during the cycle, assisting in estimates of water productivity and crop yield.

  15. Contributions to uncertainty in projections of future drought under climate change scenarios

    Directory of Open Access Journals (Sweden)

    I. H. Taylor

    2012-11-01

    Full Text Available Drought is a cumulative event, often difficult to define and involving wide reaching consequences for agriculture, ecosystems, water availability, and society. Understanding how the occurrence of drought may change in the future and which sources of uncertainty are dominant can inform appropriate decisions to guide drought impacts assessments. Uncertainties in future projections of drought arise from several sources and our aim is to understand how these sources of uncertainty contribute to future projections of drought. We consider four sources of uncertainty; climate model uncertainty associated with future climate projections, future emissions of greenhouse gases (future scenario uncertainty, type of drought (drought index uncertainty and drought event definition (threshold uncertainty. Three drought indices (the Standardised Precipitation Index (SPI, Soil Moisture Anomaly (SMA and Palmer Drought Severity Index (PDSI are calculated for the A1B and RCP2.6 future emissions scenarios using monthly model output from a 57 member perturbed parameter ensemble of climate simulations of the HadCM3C Earth system model, for the baseline period, 1961–1990, and the period 2070–2099 (representing the 2080s. We consider where there are significant increases or decreases in the proportion of time spent in drought in the 2080s compared to the baseline and compare the effects from the four sources of uncertainty. Our results suggest that, of the included uncertainty sources, choice of drought index is the most important factor influencing uncertainty in future projections of drought (60%–85% of total included uncertainty. There is a greater range of uncertainty between drought indices than that between the mitigation scenario RCP2.6 and the A1B emissions scenario (5%–6% in the 2050s to 17%–18% in the 2080s and across the different model variants in the ensemble (9%–17%. Choice of drought threshold has the least influence on uncertainty in future

  16. Climate and Hydrological Data Analysis for hydrological and solute transport modelling purposes in the Muriaé River basin, Atlantic Forest Biome, SE Brazil

    Science.gov (United States)

    Santos, Juliana; Künne, Annika; Kralisch, Sven; Fink, Manfred; Brenning, Alexander

    2016-04-01

    The Muriaé River basin in SE Brazil has been experiencing an increasing pressure on water resources, due to the population growth of the Rio de Janeiro urban area connected with the growth of the industrial and agricultural sector. This leads to water scarcity, riverine forest degradation, soil erosion and water quality problems among other impacts. Additionally the region has been suffering with seasonal precipitation variations leading to extreme events such as droughts, floods and landslides. Climate projections for the near future indicate a high inter-annual variability of rainfall with an increase in the frequency and intensity of heavy rainfall events combined with a statistically significant increase in the duration of dry periods and a reduced duration of wet periods. This may lead to increased soil erosion during the wet season, while the longer dry periods may reduce the vegetation cover, leaving the soil even more exposed and vulnerable to soil erosion. In consequence, it is crucial to understand how climate affects the interaction between the timing of extreme rainfall events, hydrological processes, vegetation growth, soil cover and soil erosion. In this context, physically-based hydrological modelling can contribute to a better understanding of spatial-temporal process dynamics in the Earth's system and support Integrated Water Resourses Management (IWRM) and adaptation strategies. The study area is the Muriaé river basin which has an area of approx. 8000 km² in Minas Gerais and Rio de Janeiro States. The basin is representative of a region of domain of hillslopes areas with the predominancy of pasture for livestock production. This study will present some of the relevant analyses which have been carried out on data (climate and streamflow) prior to using them for hydrological modelling, including consistency checks, homogeneity, pattern and statistical analyses, or annual and seasonal trends detection. Several inconsistencies on the raw data were

  17. Diagnosing Drought in a Changing Climate

    Science.gov (United States)

    Swann, A. L. S.; Hoffman, F. M.; Koven, C. D.; Randerson, J. T.

    2015-12-01

    Predictions of future climate impacts such as drought rely heavily on metrics based on changes in rainfall and changes in the demand for water from the atmosphere. However, the underlying driver of climate change is the increasing concentration of atmospheric carbon dioxide (CO2), which simultaneously increases temperature globally and modifies the water needs of plants. Although the influence of CO2 on plant stomatal conductance and transpiration is well established, the relative impact of this physiology on different drought metrics has not been rigorously assessed. We find that predictions of increasing drought stress derived using atmospheric demand metrics in many regions (including potential evapotraspiration and Palmer Drought Stress Index) correspond to places where Earth system models show stable or increasing water availability on land when assessed using the difference between precipitation and evapotranspiration. Approximately 70% of the increase in global water availability is a direct result of the effect of CO2 reducing plant water needs. Current models predict a decoupling of water flux and carbon flux, which require revisions to how aridity is measured and drought is calculated under changing CO2.

  18. Water regime and growth of young oak stands subjected to air-warming and drought on two different forest soils in a model ecosystem experiment.

    Science.gov (United States)

    Kuster, T M; Arend, M; Bleuler, P; Günthardt-Goerg, M S; Schulin, R

    2013-01-01

    Global climate change is expected to increase annual temperatures and decrease summer precipitation in Central Europe. Little is known of how forests respond to the interaction of these climate factors and if their responses depend on soil conditions. In a 3-year lysimeter experiment, we investigated the growth response of young mixed oak stands, on either acidic or calcareous soil, to soil water regime, air-warming and drought treatments corresponding to an intermediate climate change scenario. The air-warming and drought treatments were applied separately as well as in combination. The air-warming treatment had no effect on soil water availability, evapotranspiration or stand biomass. Decreased evapotranspiration from the drought-exposed stands led to significantly higher air and soil temperatures, which were attributed to impaired transpirational cooling. Water limitation significantly reduced the stand foliage, shoot and root biomass as droughts were severe, as shown in low leaf water potentials. Additional air warming did not enhance the drought effects on evapotranspiration and biomass, although more negative leaf water potentials were observed. After re-watering, evapotranspiration increased within a few days to pre-drought levels. Stands not subjected to the drought treatment produced significantly less biomass on the calcareous soil than on the acidic soil, probably due to P or Mn limitation. There was no difference in biomass and water regime between the two soils under drought conditions, indicating that nutrient availability was governed by water availability under these conditions. The results demonstrate that young oak stands can cope with severe drought and therefore can be considered for future forestry. PMID:22288508

  19. Estimation of Phosphorus Emissions in the Upper Iguazu Basin (brazil) Using GIS and the More Model

    Science.gov (United States)

    Acosta Porras, E. A.; Kishi, R. T.; Fuchs, S.; Hilgert, S.

    2016-06-01

    Pollution emissions into the drainage basin have direct impact on surface water quality. These emissions result from human activities that turn into pollution loads when they reach the water bodies, as point or diffuse sources. Their pollution potential depends on the characteristics and quantity of the transported materials. The estimation of pollution loads can assist decision-making in basin management. Knowledge about the potential pollution sources allows for a prioritization of pollution control policies to achieve the desired water quality. Consequently, it helps avoiding problems such as eutrophication of water bodies. The focus of the research described in this study is related to phosphorus emissions into river basins. The study area is the upper Iguazu basin that lies in the northeast region of the State of Paraná, Brazil, covering about 2,965 km2 and around 4 million inhabitants live concentrated on just 16% of its area. The MoRE (Modeling of Regionalized Emissions) model was used to estimate phosphorus emissions. MoRE is a model that uses empirical approaches to model processes in analytical units, capable of using spatially distributed parameters, covering both, emissions from point sources as well as non-point sources. In order to model the processes, the basin was divided into 152 analytical units with an average size of 20 km2. Available data was organized in a GIS environment. Using e.g. layers of precipitation, the Digital Terrain Model from a 1:10000 scale map as well as soils and land cover, which were derived from remote sensing imagery. Further data is used, such as point pollution discharges and statistical socio-economic data. The model shows that one of the main pollution sources in the upper Iguazu basin is the domestic sewage that enters the river as point source (effluents of treatment stations) and/or as diffuse pollution, caused by failures of sanitary sewer systems or clandestine sewer discharges, accounting for about 56% of the

  20. Study on Comprehensive Drought Monitoring Model of Winter Wheat in Hebei Province%河北省冬小麦干旱综合监测模型研究

    Institute of Scientific and Technical Information of China (English)

    康西言; 乐章燕; 车少静; 李春强

    2012-01-01

    干旱是影响河北省冬小麦生产的主要灾害之一.为了客观地辨识、监测干旱的发生发展,针对河北省冬小麦干旱监测业务服务需求,开展冬小麦干旱综合监测模型研究,选取能反映土壤、作物、大气三方面干旱的土壤相对湿度指数、作物水分亏缺距平指数、降水量距平指数,采用层次分析法确定各指数权重系数,建立冬小麦干旱综合监测模型;应用1981-2010年唐山、涿州、定州、黄骅、深县、栾城、南宫、肥乡8个农业气象观测站资料,计算各站冬小麦干旱综合指数,并对其描述干旱的能力进行分析.结果表明:当不存在旱情时,各单一指数和综合指数均可正确反映,这种情况占总样本的17.6%.当存在旱情时,综合指数克服了距平指数不能反映灌溉对旱情的影响,及土壤相对湿度指数受灌溉影响,掩盖前期旱情的不足,比较客观地反映了旱情的发生发展情况,这种情况占总样本的67.6%;同时,综合指数也克服了距平指数对降水过度敏感的不足,既能反映降水对旱情的影响,又能反映降水大小对旱情的影响程度,较单一指数能更准确的反映旱情,这种情况占总样本的14.8%.%Drought is one of the main hazards for winter wheat production in Hebei Province. Aiming at the service demand of monitoring the winter wheat drought in Hebei Province, in order to objectively identify and monitor the occurrence and development of winter wheat drought, we designed the wheat drought monitoring model. Based on the analysis of the limitations of single drought index, the soil relative moisture index, crop water deficit departure index and precipitation departure index were applied in the model of winter wheat drought monitoring, because they could reflect the drought of soil, crop and atmospheric respectively. The weight coefficient of the three drought indexes were defined by analytic hierarchy method. Data were selected

  1. 基于水文模型的滦河流域综合干旱指数研究%Based on the Hydrological Model to Build Integrated Drought Index in Luanhe Basin

    Institute of Scientific and Technical Information of China (English)

    屈海晨; 胡艳阳; 刘晓东

    2015-01-01

    Soil moisture is an important indicator of watershed judgment of drought,which was measured with a one-sided, and unpredictable,but hydrological model can effectively simulate soil moisture throughout the basin. With Luan River basin above the county hydrological station as a research area,based on soil moisture runoff model to simulate vertical mixing basin, the relative soil moisture drought index is constructed. Through the principal component analysis the relative soil moisture, precipitation anomaly percentage and relative wetting degree are integrated to build a comprehensive drought index in order to make a quantitative assessment of the frequency of the different time scales Watershed(year,month,quarter scale)drought. The results show that:the comprehensive drought index can be used to Luan River drought assessment,and drought events that have occurred have better goodness of fit;1960—1989 in Luan River Basin the maximum frequency of special drought for three months is 18.23 percent ,the highest frequency of continuous drought for five months is 17.26 percent,the frequency of light drought for seven months is 9.24 percent;in Luan River Basin the highest frequency of drought in winter is 37.8 percent , the lower frequency of drought in summer is 22.6 percent,the frequencies of severe drought and average drought in winter are respectively 6.0 percent and 11.3 percent,the maximum frequency of special drought in spring is 3.5 percent,the frequency of light drought in summer is 18.1 percent.The results is important to predict the drought in Luanhe basin.%土壤墒情是判定流域干旱的一个重要指标,其测定具有片面性且无法预测,而水文模型可有效模拟整个流域的土壤含水量。以滦河滦县水文站以上流域作为研究区域,基于垂向混合产流模型模拟流域土壤含水量,构建土壤相对湿润度干旱指数,并运用主成分分析法将土壤相对湿润度、降水距平

  2. Monthly hydrometeorological ensemble prediction of streamflow droughts and corresponding drought indices

    Directory of Open Access Journals (Sweden)

    F. Fundel

    2013-01-01

    Full Text Available Streamflow droughts, characterized by low runoff as consequence of a drought event, affect numerous aspects of life. Economic sectors that are impacted by low streamflow are, e.g., power production, agriculture, tourism, water quality management and shipping. Those sectors could potentially benefit from forecasts of streamflow drought events, even of short events on the monthly time scales or below. Numerical hydrometeorological models have increasingly been used to forecast low streamflow and have become the focus of recent research. Here, we consider daily ensemble runoff forecasts for the river Thur, which has its source in the Swiss Alps. We focus on the evaluation of low streamflow and of the derived indices as duration, severity and magnitude, characterizing streamflow droughts up to a lead time of one month.

    The ECMWF VarEPS 5-member ensemble reforecast, which covers 18 yr, is used as forcing for the hydrological model PREVAH. A thorough verification reveals that, compared to probabilistic peak-flow forecasts, which show skill up to a lead time of two weeks, forecasts of streamflow droughts are skilful over the entire forecast range of one month. For forecasts at the lower end of the runoff regime, the quality of the initial state seems to be crucial to achieve a good forecast quality in the longer range. It is shown that the states used in this study to initialize forecasts satisfy this requirement. The produced forecasts of streamflow drought indices, derived from the ensemble forecasts, could be beneficially included in a decision-making process. This is valid for probabilistic forecasts of streamflow drought events falling below a daily varying threshold, based on a quantile derived from a runoff climatology. Although the forecasts have a tendency to overpredict streamflow droughts, it is shown that the relative economic value of the ensemble forecasts reaches up to 60%, in case a forecast user is able to take preventive

  3. Assessing vulnerability to drought: identifying underlying factors across Europe

    Science.gov (United States)

    Urquijo, Julia; Gonzalez Tánago, Itziar; Ballesteros, Mario; De Stefano, Lucia

    2015-04-01

    Drought is considered one of the most severe and damaging natural hazards in terms of people and sectors affected and associated losses. Drought is a normal and recurrent climatic phenomenon that occurs worldwide, although its spatial and temporal characteristics vary significantly among climates. In the case of Europe, in the last thirty years, the region has suffered several drought events that have caused estimated economic damages over a €100 billion and have affected almost 20% of its territory and population. In recent years, there has been a growing awareness among experts and authorities of the need to shift from a reactive crisis approach to a drought risk management approach, as well as of the importance of designing and implementing policies, strategies and plans at country and river basin levels to deal with drought. The identification of whom and what is vulnerable to drought is a central aspect of drought risk mitigation and planning and several authors agree that societal vulnerability often determines drought risk more than the actual precipitation shortfalls. The final aim of a drought vulnerability assessment is to identify the underlying sources of drought impact, in order to develop policy options that help to enhance coping capacity and therefore to prevent drought impact. This study identifies and maps factors underlying vulnerability to drought across Europe. The identification of factors influencing vulnerability starts from the analysis of past drought impacts in four European socioeconomic sectors. This analysis, along with an extensive literature review, led to the selection of vulnerability factors that are both relevant and adequate for the European context. Adopting the IPCC model, vulnerability factors were grouped to describe exposure, sensitivity and adaptive capacity. The aggregation of these components has resulted in the mapping of vulnerability to drought across Europe at NUTS02 level. Final results have been compared with

  4. Drought in the Emerald City

    International Nuclear Information System (INIS)

    This paper discusses a drought preparedness study being conducted for the Cedar River and Green River basins in western Washington state. The study is one of four regional case studies being managed by the U.S. Army Corps of Engineers as part of the National Study of Water Management During Drought. The overriding objective of the drought preparedness study is to leave the region better prepared for drought, through demonstration and test of drought preparedness tools and strategies. The study has served as a vehicle to promote a greater regional focus on drought related water supply problem solving. The 1992 drought in the Seattle/Tacoma metropolitan area provided a unique opportunity for the study team to demonstrate approaches to drought management being researched and tested as part of the study

  5. Forecasting solar irradiation using WRF model and refining statistics for Northeastern Brazil

    Science.gov (United States)

    Pereira, E. B.; Lima, F. J. L.; Martins, F. R.

    2015-12-01

    Solar energy is referred to as variable generation sources because their electricity production varies based on the availability of sun irradiance. To accommodate this variability, electricity grid operators use a variety of tools to maintain a reliable electricity supply, one of them is to forecast solar irradiation, and to adjust other electricity sources as needed. This work reports an approach to forecast solar irradiation in the Brazilian Northeastern region (NEB) by using statistically post-processing data from mesoscale model outputs. The method assimilates the diversity of climate characteristics occurring in the region presenting the largest solar energy potentials in Brazil. Untreated solar irradiance forecasts for 24h in advance were obtained using the WRF model runs. Cluster analysis technique was employed to find out areas presenting similar climate characteristics and to reduce uncertainties. Comparison analysis between WRF model outputs and site-specific measured data were performed to evaluate the model skill in forecasting the surface solar irradiation. After that, post-processing of WRF outputs using artificial neural networks (ANNs) and multiple regression methods refined the short-term solar irradiation forecasts. A set of pre-selected variables of the WRF model outputs representing the forecasted atmospheric conditions were used as predictors by the ANNs. Several predictors were tested in the adjustment and simulation of the ANNs. We found the best ANNs architecture and a group of 10 predictors, with which more in-depth analyzes were carried out, including performance evaluation for fall and spring of 2011 (rainy and dry season in NEB). The site-specific measured solar radiation data came from 110 stations distributed throughout the NEB. Data for the rainy season were acquired from March to May, and for the dry season from September to November. We concluded that the untreated numerical forecasts of solar irradiation provided by WRF exhibited a

  6. A Bayesian Network-Based Probabilistic Framework for Drought Forecasting and Outlook

    OpenAIRE

    Ji Yae Shin; Muhammad Ajmal; Jiyoung Yoo; Tae-Woong Kim

    2016-01-01

    Reliable drought forecasting is necessary to develop mitigation plans to cope with severe drought. This study developed a probabilistic scheme for drought forecasting and outlook combined with quantification of the prediction uncertainties. The Bayesian network was mainly employed as a statistical scheme for probabilistic forecasting that can represent the cause-effect relationships between the variables. The structure of the Bayesian network-based drought forecasting (BNDF) model was designe...

  7. Bivariate Drought Analysis Using Streamflow Reconstruction with Tree Ring Indices in the Sacramento Basin, California, USA

    OpenAIRE

    Jaewon Kwak; Soojun Kim; Gilho Kim; Singh, Vijay P; Jungsool Park; Hung Soo Kim

    2016-01-01

    Long-term streamflow data are vital for analysis of hydrological droughts. Using an artificial neural network (ANN) model and nine tree-ring indices, this study reconstructed the annual streamflow of the Sacramento River for the period from 1560 to 1871. Using the reconstructed streamflow data, the copula method was used for bivariate drought analysis, deriving a hydrological drought return period plot for the Sacramento River basin. Results showed strong correlation among drought characteris...

  8. Coping With Droughts

    Science.gov (United States)

    Zaporozec, Alexander

    This book is a collection of selected papers from the NATO Advanced Study Institute on Droughts entitled “Drought Impact Control Technology,” held at the National Laboratory of Civil Engineering in Lisbon, Portugal, in June 1980. The editors of the book have chosen a nontraditional but successful approach to presenting the papers. Instead of including a verbatim proceedings of the institute, they assembled 21 papers presented by 14 of the institute's lecturers, reshaped and synthesized them, and supplemented them by five new papers that cover obvious gaps in topics. The result is enlightening reading and a more or less complete presentation of the subject. The edited material in the book was arranged around three central themes related to efforts needed to cope with or manage the droughts. In the process, the identity of individual contributors has been preserved.

  9. Global trends in future hydrological drought

    Science.gov (United States)

    Van Lanen, H.; Wanders, N.; Wada, Y.

    2013-12-01

    Climate change very likely impacts future hydrological drought characteristics worldwide (i.e. duration and intensity of drought in runoff). However, the magnitude and sign of the change is largely unknown. In this study we quantify impact of climate change on future low flows and hydrological droughts characteristics on a global scale. The global hydrological and water resources model PCR-GLOBWB was used to simulate future river runoff at 0.5 degree globally on a daily basis. The newly available CMIP5 climate projections were obtained through the Inter-Sectoral Impact Model Intercomparison Project (ISI-MIP). The model was forced with the daily transient climate fields taken from five GCMs and four underlying emission scenarios (here accounted for by using four Representative Concentration Pathways or RCPs). The monthly Q80 (20 percentile lowest flow) was used to evaluate the changes in low flows and as the threshold level for the hydrological drought characterisation. The monthly threshold was smoothed to allow for drought calculations on a daily basis. The thresholds in the future remained transient and were calculated over the climatology of the last 30 year period to reflect the adaptation of society to new conditions. Trends in the thresholds and drought characteristics were analysed over the period 2000-2099. Results for most GCMs and all RCPs showed that Q80 discharge (low flow metric) indicates a significant negative trend in large parts of South America, Central Africa, the Mediterranean and South East Asia. Under the higher greenhouse gas emission scenarios of RCP6.0 and RCP8.5, the USA and Central and South Europe were also projected to have drier conditions. For all future projections Russia and Canada were expected to get wetter during the 21st century. Under RCP6.0 and RCP8.5 scenarios, the results generally showed the strongest negative changes in future low flow. The results simulated with most GCMs agree well over many parts of the world, however

  10. Modeling Soil Water in the Caatinga Tropical Dry Forest of Northeastern Brazil

    Science.gov (United States)

    Wright, C.; Wilcox, B.; Souza, E.; Lima, J. R. D. S.; West, J. B.

    2015-12-01

    The Caatinga is a tropical dry forest unique to northeastern Brazil. It has a relatively high degree of endism and supports a population of about 20 million subsistence farmers. However, it is poorly understood, under-researched and often over-looked in regards to other Brazilian ecosystems. It is a highly perturbed system that suffers from deforestation, land use change, and may be threatened by climate change. How these perturbations affect hydrology is unknown, but may have implications for biodiversity and ecosystem services and resiliency. Therefore, understanding key hydrological processes is critical, particularly as related to deforestation. In this study, Hydrus 1D, which is based on van Genuchten parameters to describe the soil water curve and Richard's Equation to describe flow in the vadose zone, was used to model soil moisture in the Caatinga ecosystem. The aim was 1) to compare hydraulic characterization between a forested Caatinga site and a deforested pasture site, 2) to analyze inter-annual variability, and 3) to compare with observed soil moisture data. Hydraulic characterization included hydraulic conductivity, infiltration, water content and pressure head trends. Van Genuchten parameters were derived using the Beerkan method, which is based on soil texture, particle distribution, as well as in-situ small-scale infiltration experiments. Observational data included soil moisture and precipitation logged every half-hour from September 2013 to April 2014 to include the dry season and rainy season. It is expected that the forested Caatinga site will have a higher hydraulic conductivity as well as retain higher soil moisture values. These differences may be amplified during the dry season, as water resources become scarce. Deviations between modeled data and observed data will allow for further hypothesis to be proposed, especially those related to soil water repellency. Hence, these results may indicate difference in soil water dynamics between a

  11. Drought Risk Identification: Early Warning System of Seasonal Agrometeorological Drought

    Science.gov (United States)

    Dalecios, Nicolas; Spyropoulos, Nicos V.; Tarquis, Ana M.

    2014-05-01

    By considering drought as a hazard, drought types are classified into three categories, namely meteorological or climatological, agrometeorological or agricultural and hydrological drought and as a fourth class the socioeconomic impacts can be considered. This paper addresses agrometeorological drought affecting agriculture within the risk management framework. Risk management consists of risk assessment, as well as a feedback on the adopted risk reduction measures. And risk assessment comprises three distinct steps, namely risk identification, risk estimation and risk evaluation. This paper deals with the quantification and monitoring of agrometeorological drought, which constitute part of risk identification. For the quantitative assessment of agrometeorological or agricultural drought, as well as the computation of spatiotemporal features, one of the most reliable and widely used indices is applied, namely the Vegetation Health Index (VHI). The computation of VHI is based on satellite data of temperature and the Normalized Difference Vegetation Index (NDVI). The spatiotemporal features of drought, which are extracted from VHI are: areal extent, onset and end time, duration and severity. In this paper, a 20-year (1981-2001) time series of NOAA/AVHRR satellite data is used, where monthly images of VHI are extracted. Application is implemented in Thessaly, which is the major agricultural region of Greece characterized by vulnerable and drought-prone agriculture. The results show that every year there is a seasonal agrometeorological drought with a gradual increase in the areal extent and severity with peaks appearing usually during the summer. Drought monitoring is conducted by monthly remotely sensed VHI images. Drought early warning is developed using empirical relationships of severity and areal extent. In particular, two second-order polynomials are fitted, one for low and the other for high severity drought, respectively. The two fitted curves offer a seasonal

  12. Drought, Mortality and Social Structure.

    Science.gov (United States)

    Sharma, Sanjay

    1995-01-01

    Examines the relationship between the human population explosion, resource depletion, drought, malnutrition, and disease. As a sample study, mortality trends in Rajasthan State in India in the 1980s were analyzed to correlate the increased death rate with the drought of 1987. It is demonstrated that drought-induced malnutrition was the root cause…

  13. Anthropogenic climate change affects meteorological drought risk in Europe

    International Nuclear Information System (INIS)

    Drought constitutes a significant natural hazard in Europe, impacting societies and ecosystems across the continent. Climate model simulations with increasing greenhouse gas concentrations project increased drought risk in southern Europe, and on the other hand decreased drought risk in the north. Observed changes in water balance components and drought indicators resemble the projected pattern. However, assessments of possible causes of the reported regional changes have so far been inconclusive. Here we investigate whether anthropogenic emissions have altered past and present meteorological (precipitation) drought risk. For doing so we first estimate the magnitude of 20 year return period drought years that would occur without anthropogenic effects on the climate. Subsequently we quantify to which degree the occurrence probability, i.e. the risk, of these years has changed if anthropogenic climate change is accounted for. Both an observational and a climate model-based assessment suggest that it is >95% likely that human emissions have increased the probability of drought years in the Mediterranean, whereas it is >95% likely that the probability of dry years has decreased in northern Europe. In central Europe the evidence is inconclusive. The results highlight that anthropogenic climate change has already increased drought risk in southern Europe, stressing the need to develop efficient mitigation measures. (letter)

  14. Wind Power Energy in Southern Brazil: evaluation using a mesoscale meteorological model

    Science.gov (United States)

    Krusche, Nisia; Stoevesandt, Bernhard; Chang, Chi-Yao; Peralta, Carlos

    2015-04-01

    In recent years, several wind farms were build in the coast of Rio Grande do Sul state. This region of Brazil was identified, in wind energy studies, as most favorable to the development of wind power energy, along with the Northeast part of the country. Site assessments of wind power, over long periods to estimate the power production and forecasts over short periods can be used for planning of power distribution and enhancements on Brazil's present capacity to use this resource. The computational power available today allows the simulation of the atmospheric flow in great detail. For instance, one of the authors participated in a research that demonstrated the interaction between the lake and maritime breeze in this region through the use of a atmospheric model. Therefore, we aim to evaluate simulations of wind conditions and its potential to generate energy in this region. The model applied is the Weather Research and Forecasting , which is the mesoscale weather forecast software. The calculation domain is centered in 32oS and 52oW, in the southern region of Rio Grande do Sul state. The initial conditions of the simulation are taken from the global weather forecast in the time period from October 1st to October 31st, 2006. The wind power potential was calculated for a generic turbine, with a blade length of 52 m, using the expression: P=1/2*d*A*Cp*v^3, where P is the wind power energy (in Watts), d is the density (equal to 1.23 kg/m^3), A is the area section, which is equal to 8500 m2 , and v is the intensity of the velocity. The evaluation was done for a turbine placed at 50 m and 150 m of height. A threshold was chosen for a turbine production of 1.5 MW to estimate the potential of the site. In contrast to northern Brazilian region, which has a rather constant wind condition, this region shows a great variation of power output due to the weather variability. During the period of the study, at least three frontal systems went over the region, and thre was a

  15. A theoretical drought classification method for the multivariate drought index based on distribution properties of standardized drought indices

    Science.gov (United States)

    Hao, Zengchao; Hao, Fanghua; Singh, Vijay P.; Xia, Youlong; Ouyang, Wei; Shen, Xinyi

    2016-06-01

    Drought indices have been commonly used to characterize different properties of drought and the need to combine multiple drought indices for accurate drought monitoring has been well recognized. Based on linear combinations of multiple drought indices, a variety of multivariate drought indices have recently been developed for comprehensive drought monitoring to integrate drought information from various sources. For operational drought management, it is generally required to determine thresholds of drought severity for drought classification to trigger a mitigation response during a drought event to aid stakeholders and policy makers in decision making. Though the classification of drought categories based on the univariate drought indices has been well studied, drought classification method for the multivariate drought index has been less explored mainly due to the lack of information about its distribution property. In this study, a theoretical drought classification method is proposed for the multivariate drought index, based on a linear combination of multiple indices. Based on the distribution property of the standardized drought index, a theoretical distribution of the linear combined index (LDI) is derived, which can be used for classifying drought with the percentile approach. Application of the proposed method for drought classification of LDI, based on standardized precipitation index (SPI), standardized soil moisture index (SSI), and standardized runoff index (SRI) is illustrated with climate division data from California, United States. Results from comparison with the empirical methods show a satisfactory performance of the proposed method for drought classification.

  16. The Impacts of Droughts in Tropical Forests.

    Science.gov (United States)

    Corlett, Richard T

    2016-07-01

    Tropical forests exchange more carbon dioxide (CO2) with the atmosphere than any other vegetation type and, thus, form a crucial component of the global carbon cycle. However, the impacts of anthropogenic climate change on drought occurrence and intensity could weaken the tropical forest carbon sink, with resulting feedback to future climates. We urgently need a better understanding of the mechanisms and processes involved to predict future responses of tropical forest carbon sequestration to climate change. Recent progress has been made in the study of drought responses at the molecular, cellular, organ, individual, species, community, and landscape levels. Although understanding of the mechanisms is incomplete, the models used to predict drought impacts could be significantly improved by incorporating existing knowledge.

  17. Assessment of natural dynamics and anthropogenic impacts on residence times in the urban aquifers of Recife (Brazil) using a multi- tracer approach (noble gases, CFCs, SF6, 14C)

    OpenAIRE

    Chatton, Eliot; Labasque, Thierry; Aquilina, Luc; Petelet-Giraud, Emmanuelle; Cary, Lise; Bertrand, Guillaume; Hochreutener, Rébecca

    2015-01-01

    The Metropolitan Region of Recife (RMR) is an urban area of the northeastern coast of Brazil located in an estuary zone and overlying a complex multi-layered sedimentary set. Over the last decades, population growth and recurrent droughts have been increasing the pressures on the aquifers of the region (over-exploitation, contamination and salinization). Through a multi-tracer approach (major and noble gases, CFCs, SF6, 14C) and the implementation of an inverse model to infer recharge conditi...

  18. Diverging trends between meteorological drought indices (SPI and SPEI) in Europe

    Science.gov (United States)

    Stagge, James; Kingston, Daniel; Tallaksen, Lena; Hannah, David

    2016-04-01

    Severe European droughts over the last decade and climate change projections of increased regional drought severity for the Mediterranean and eastern Europe make understanding drought events in a non-stationary climate a major scientific and practical concern for Europe. Additionally, the existence of numerous differing drought metrics is a challenge for the robust detection of drought occurrence trends. This research addresses these issues by testing the hypotheses that (a) there have been recent trends in meteorological drought severity across Europe, and (b) that the choice of drought index significantly affects these observed trends. Meteorological drought is quantified in this study using the 6-month Standardized Precipitation Index (SPI-6) and Standardized Precipitation-Evapotranspiration Index (SPEI-6), which are commonly recommended drought metrics that measure accumulated precipitation and climatic water balance (precipitation minus reference potential evapotranspiration), respectively. Climate data are based on the WATCH Forcing Data (WFD) and WFD ERA-Interim (WFDEI) datasets, which together cover the period 1958-2014. Trends in percentage of European land area in drought were calculated for this 56 year period by defining drought as occurring below the 20th index percentile (SPI/SPEI SPEI-6 drought area have been moderate, with a slight decrease in precipitation-only drought (SPI) area and a slight increase in climatic water balance drought (SPEI) area. The observed spatial trends in drought frequency are consistent with climate model output, with increases in drought frequency for southern Europe and decreases across northern Europe. However, the difference between percentage drought area measured using these two indices has steadily increased. Investigating the constituent climate variables shows that the increasing divergence between drought measured by SPI and SPEI is driven by an increase in temperature and thus PET, which is only accounted for in

  19. Analysis of a general circulation model product. I - Frontal systems in the Brazil/Malvinas and Kuroshio/Oyashio regions

    Science.gov (United States)

    Garzoli, Silvia L.; Garraffo, Zulema; Podesta, Guillermo; Brown, Otis

    1992-01-01

    The general circulation model (GCM) of Semtner and Chervin (1992) is tested by comparing the fields produced by this model with available observations in two western boundary current regions, the Brazil/Malvinas and the Kuroshio/Oyashio confluences. The two sets of data used are the sea surface temperature from satellite observations and the temperature field product from the GCM at levels 1 (12.5 m), 2 (37.5 m), and 6 (160 m). It is shown that the model reproduces intense thermal fronts at the sea surface and in the upper layers (where they are induced by the internal dynamics of the model). The location of the fronts are reproduced in the model within 4 to 5 deg, compared with observations. However, the variability of these fronts was found to be less pronounced in the model than in the observations.

  20. Drought and groundwater management

    DEFF Research Database (Denmark)

    Amundsen, Eirik S; Jensen, Frank

    This paper considers the problem of a water management authority faced with the threat of a drought that hits at an uncertain date. Three management policies are investigated: i) a laissez-faire (open-access) policy of automatic adjustment through a zero marginal private net benefit condition, ii...

  1. Probabilistic forecasting of seasonal drought behaviors in the Huai River basin, China

    Science.gov (United States)

    Xiao, Mingzhong; Zhang, Qiang; Singh, Vijay P.; Chen, Xiaohong

    2016-01-01

    The Huai River basin is one of the major supplier of agricultural products in China, and droughts have critical impacts on agricultural development. Good knowledge of drought behaviors is of great importance in the planning and management of agricultural activities in the Huai River basin. With the copula functions to model the persistence property of drought, the probabilistic seasonal drought forecasting models have been built in the Huai River basin. In this study, droughts were monitored by the Standardized Precipitation Evapotranspiration Index (SPEI) with the time scales of 3, 6, and 9 months, and their composite occurrence probability has been used to forecast the seasonal drought. Results indicated that the uncertainty related to the predicted seasonal drought is larger when more severe droughts occurred in the previous seasons, and the severe drought which occurs in summer and autumn will be more likely to be persistent in the next season while the severe drought in winter and spring will be more likely to be recovered in the subsequent season. Furthermore, given the different drought statuses in the previous season, spatial patterns of the predicted drought events with the largest occurrence probability have also been investigated, and results indicate that the Huai River basin is vulnerable to the extreme drought in most parts of the basin, e.g., the severe drought in winter will be more likely to be persistent in spring in the central part of the southern Huai River basin. Such persistent drought events pose serious challenges for planning and management of agricultural irrigation, then results of the study will be valuable for the planning of crop cultivation or mitigation of the losses caused by drought in the Huai River basin, China.

  2. A new framework for evaluating the impacts of drought on net primary productivity of grassland.

    Science.gov (United States)

    Lei, Tianjie; Wu, Jianjun; Li, Xiaohan; Geng, Guangpo; Shao, Changliang; Zhou, Hongkui; Wang, Qianfeng; Liu, Leizhen

    2015-12-01

    This paper presented a valuable framework for evaluating the impacts of droughts (single factor) on grassland ecosystems. This framework was defined as the quantitative magnitude of drought impact that unacceptable short-term and long-term effects on ecosystems may experience relative to the reference standard. Long-term effects on ecosystems may occur relative to the reference standard. Net primary productivity (NPP) was selected as the response indicator of drought to assess the quantitative impact of drought on Inner Mongolia grassland based on the Standardized Precipitation Index (SPI) and BIOME-BGC model. The framework consists of six main steps: 1) clearly defining drought scenarios, such as moderate, severe and extreme drought; 2) selecting an appropriate indicator of drought impact; 3) selecting an appropriate ecosystem model and verifying its capabilities, calibrating the bias and assessing the uncertainty; 4) assigning a level of unacceptable impact of drought on the indicator; 5) determining the response of the indicator to drought and normal weather state under global-change; and 6) investigating the unacceptable impact of drought at different spatial scales. We found NPP losses assessed using the new framework were more sensitive to drought and had higher precision than the long-term average method. Moreover, the total and average losses of NPP are different in different grassland types during the drought years from 1961-2009. NPP loss was significantly increased along a gradient of increasing drought levels. Meanwhile, NPP loss variation under the same drought level was different in different grassland types. The operational framework was particularly suited for integrative assessing the effects of different drought events and long-term droughts at multiple spatial scales, which provided essential insights for sciences and societies that must develop coping strategies for ecosystems for such events. PMID:26204052

  3. Modeling the Paranagua Estuarine Complex, Brazil: tidal circulation and cotidal charts

    Directory of Open Access Journals (Sweden)

    Ricardo de Camargo

    2003-01-01

    Full Text Available The tidal circulation in Paranagua Bay (Parana State, Southern Brazil was studied based on the Princeton Ocean Model. The model domain covered the near shore region and the estuarine area, with about 1 km grid resolution in cross-shore and along-shore directions. Homogeneous and diagnostic distributions for temperature and salinity were used and 12 tidal constituents were considered to specify the elevations at the open boundaries. Tidal analysis of 29-days time series of elevations and currents for each grid point generated corange and cophase lines as well as the correspondent axes of the current ellipses for each constituent. These computed values reproduced well the observed amplifications and phase lags of surface elevations and currents. Residual flows show the formation of tidal eddies, related to coastal geometry and bottom topography.A circulação de maré na Baía de Paranaguá (Estado do Paraná, sul do Brasil foi estudada através do Princeton Ocean Model. O domino do modelo abrange a região costeira adjacente e a área estuarina, com resolução de aproximadamente I km nas direções perpendicular e paralela à costa. Distribuições homogêneas e diagnosticas para temperatura e salinidade foram usadas e 12 constituintes de maré especificaram as elevações de superfície nos contornos abertos. Análises de maré de séries temporais de 29 dias de elevações e correntes para cada ponto de grade geraram linhas cotidais de amplitude e de fase, assim como elipses de correntes, para cada constituinte. Os valores obtidos pelo modelo reproduziram satisfatoriamente as amplificações e defasagens observadas nas elevações e correntes de superfície. Fluxos residuais mostram a formação de vórtices de maré, relacionados com a geometria da costa e a topografia do fundo.

  4. Projected Changes in Evapotranspiration Rates over Northeast Brazil

    Science.gov (United States)

    Costa, Alexandre; Guimarães, Sullyandro; Vasconcelos, Francisco, Jr.; Sales, Domingo; da Silva, Emerson

    2015-04-01

    Climate simulations were performed using a regional model (Regional Atmospheric Modeling System, RAMS 6.0) driven by data from one of the CMIP5 models (Hadley Centre Global Environmental Model, version 2 - Earth System, HadGEM2-ES) over two CORDEX domains (South America and Central America) for the heavy-emission scenario (RCP8.5). Potential evapotranspiraion data from the RCM and from the CMIP5 global models were analyzed over Northeast Brazil, a semiarid region with a short rainy season (usually February to May in its northern portion due to the seasonal shift of the Intertropical Convergence Zone) and over which droughts are frequent. Significant changes in the potential evapotranspiration were found, with most models showing a increasing trend along the 21st century, which are expected to alter the surface water budget, increasing the current water deficit (precipitation is currently much smaller than potential evapotranspiration). Based on the projections from the majority of the models, we expect important impacts over local agriculture and water resources over Northeast Brazil.

  5. A drought-based predictor of recent haze events in western Indonesia

    Science.gov (United States)

    Field, Robert D.; Wang, Yonghe; Roswintiarti, Orbita; Guswanto

    Indonesia's fire and haze problem is reviewed, and a model quantifying the relationship between drought and haze from biomass burning in western Indonesia is presented. Visibility observations from weather stations in Sumatra and Kalimantan were used as a haze indicator. The Drought Code component of the Canadian Forest Fire Weather Index System was used as a drought indicator. Using meteorological data from 1994 to 1998, we obtained regional haze and drought signals for western Indonesia. Nonlinear regression analysis was performed between the two signals to obtain a model of haze potential based on the Drought Code. Using the curvature properties of the nonlinear model, we estimated that severe haze is likely above a threshold Drought Code of 388.2. Using this threshold value, we propose four levels of drought that can be used operationally as an early warning tool in managing Indonesia's serious haze problem.

  6. Modeling the land requirements and potential productivity of sugarcane and jatropha in Brazil and India using the LPJmL dynamic global vegetation model

    Energy Technology Data Exchange (ETDEWEB)

    Lapola, David M. [Center for Environmental Systems Research, University of Kassel, D-34109 Kassel (Germany); International Max Planck Research School on Earth System Modeling, D-20146 Hamburg (Germany); Priess, Joerg A. [Center for Environmental Systems Research, University of Kassel, D-34109 Kassel (Germany); Bondeau, Alberte [Potsdam Institute for Climate Impact Research, D-14412 Potsdam (Germany)

    2009-08-15

    The governments of Brazil and India are planning a large expansion of bioethanol and biodiesel production in the next decade. Considering that limitation of suitable land and/or competition with other land uses might occur in both countries, assessments of potential crop productivity can contribute to an improved planning of land requirements for biofuels under high productivity or marginal conditions. In this paper we model the potential productivity of sugarcane and jatropha in both countries. Land requirements for such expansions are calculated according to policy scenarios based on government targets for biofuel production in 2015. Spatial variations in the potential productivity lead to rather different land requirements, depending on where plantations are located. If jatropha is not irrigated, land requirements to fulfill the Indian government plans in 2015 would be of 410 000 to 95 000 km{sup 2} if grown in low or high productivity areas respectively (mean of 212 000 km{sup 2}). In Brazil land requirements, are of 18 000-89 000 km{sup 2} (mean of 29 000 km{sup 2}), suggesting a promising substitute to soybean biodiesel. Although future demand for sugarcane ethanol in Brazil is approximately ten times larger than in India, land requirements are comparable in both countries due to large differences in ethanol production systems. In Brazil this requirement ranges from 25 000 to 211 000 km{sup 2} (mean of 33 000 km{sup 2}) and in India from 7000 to 161 000 km{sup 2} (mean 17 000 km{sup 2}). Irrigation could reduce the land requirements by 63% and 41% (24% and 15%) in India (Brazil) for jatropha and sugarcane respectively. (author)

  7. Future hydrological drought in the context of water scarcity

    Science.gov (United States)

    van Lanen, Henny A. J.; Wanders, Niko

    2013-04-01

    Observations show that droughts and water scarcity have increased over the last decades in Europe. In particular summer low flows show downward trends in vast areas (only in Scandinavia wetting trends occur). The lower water availability and the enhanced water demands led to growing water scarcity and increasing challenges for water management to assess future water resources and to develop a pro-active approach. A key element in the assessment is how drought will develop, i.e. will drought become more severe (frequency, intensity, spatial scale, location). Hydrological drought (groundwater and streamflow) development is the most relevant among drought types for water resources assessment. This study presents the likely change of hydrological droughts characteristics in the 21st century as a result of climate change across the world. Magnitude and directionality of these changes and their dependency on climatology and catchment characteristics, is largely unknown. A conceptual hydrological model was forced with downscaled and bias-corrected outcome from three General Circulation Models (GCM forced models), A2 emission scenario The same hydrological model was also forced with the WATCH Forcing re-analysis dataset (reference model). The variable threshold level method was applied to identify hydrological drought occurrence, duration and severity in time series of simulated discharge. Results for the control period (1971-2000) show that the drought characteristics of the GCM forced models reasonably agree with the reference model implying that the climate models produce realistic outcome for global drought analyses. For the near future (2021-2050) and far future (2071-2100) the GCM forced models project a global average decrease in drought occurrence (67-74% end of 21st century), indicating that the number of drought days per year will become lower. However, all three GCM forced models project a substantial increase of both average drought duration (43-57%) and

  8. Spatial evaluation and modeling of Dengue seroprevalence and vector density in Rio de Janeiro, Brazil.

    Directory of Open Access Journals (Sweden)

    Nildimar Alves Honório

    Full Text Available BACKGROUND: Rio de Janeiro, Brazil, experienced a severe dengue fever epidemic in 2008. This was the worst epidemic ever, characterized by a sharp increase in case-fatality rate, mainly among younger individuals. A combination of factors, such as climate, mosquito abundance, buildup of the susceptible population, or viral evolution, could explain the severity of this epidemic. The main objective of this study is to model the spatial patterns of dengue seroprevalence in three neighborhoods with different socioeconomic profiles in Rio de Janeiro. As blood sampling coincided with the peak of dengue transmission, we were also able to identify recent dengue infections and visually relate them to Aedes aegypti spatial distribution abundance. We analyzed individual and spatial factors associated with seroprevalence using Generalized Additive Model (GAM. METHODOLOGY/PRINCIPAL FINDINGS: Three neighborhoods were investigated: a central urban neighborhood, and two isolated areas characterized as a slum and a suburban area. Weekly mosquito collections started in September 2006 and continued until March 2008. In each study area, 40 adult traps and 40 egg traps were installed in a random sample of premises, and two infestation indexes calculated: mean adult density and mean egg density. Sera from individuals living in the three neighborhoods were collected before the 2008 epidemic (July through November 2007 and during the epidemic (February through April 2008. Sera were tested for DENV-reactive IgM, IgG, Nested RT-PCR, and Real Time RT-PCR. From the before-after epidemics paired data, we described seroprevalence, recent dengue infections (asymptomatic or not, and seroconversion. Recent dengue infection varied from 1.3% to 14.1% among study areas. The highest IgM seropositivity occurred in the slum, where mosquito abundance was the lowest, but household conditions were the best for promoting contact between hosts and vectors. By fitting spatial GAM we found

  9. GEOWOW: a drought scenario for multidisciplinary data access and use

    Science.gov (United States)

    Santoro, Mattia; Sorichetta, Alessandro; Roglia, Elena; Craglia, Massimo; Nativi, Stefano

    2013-04-01

    Recent enhancements of the GEOSS Common Infrastructure (GCI; http://www.earthobservations.org/gci_gci.shtml), and in particular the introduction of a middleware in the GCI that brokers across heterogeneous information systems, have increased significantly the number of information resources discoverable worldwide. Now the challenge moves to the next level of ensuring access and use of the resources discovered, which have many different and domain-specific data models, communication protocols, encoding formats, etc. The GEOWOW Project - GEOSS interoperability for Weather, Ocean and Water, http://www.geowow.eu - developed a set of multidisciplinary use scenarios to advance the present GCI. This work describes the "Easy discovery and use of GEOSS resources for addressing multidisciplinary challenges related to drought scenarios" showcase demonstrated at the last GEO Plenary in Foz de Iguazu (Brazil). The scientific objectives of this showcase include: prevention and mitigation of water scarcity and drought situations, assessment of the population and geographical area potentially affected, evaluation of the possible distribution of mortality and economic loss risk, and support in building greater capacity to cope with drought. The need to address these challenges calls for producing scientifically robust and consistent information about the extent of land affected by drought and degradation. Similarly, in this context it is important: (i) to address uncertainties about the way in which various biological, physical, social, and economic factors interact each other and influence the occurrence of drought events, and (ii) to develop and test adequate indices and/or combination of them for monitoring and forecasting drought in different geographic locations and at various spatial scales (Brown et al., 2002). The scientific objectives above can be met with an increased interoperability across the multidisciplinary domains relevant to this drought scenario. In particular

  10. Multi-GCM Projections of Global Drought Conditions With Use of the Palmer Drought Indices

    Science.gov (United States)

    Dubrovsky, M.; Svoboda, M.; Trnka, M.; Hayes, M.; Wilhite, D.; Zalud, Z.

    2007-12-01

    We use two Palmer Drought Indices (the PDSI and Z-index) to assess the drought conditions in future climates as projected by seven Global Climate Models (GCMs). Both indices are based on precipitation and temperature data (this makes them more suitable for climate change impact studies compared to the Standardized Precipitation Index, which is based only on precipitation) and the available water content of the soil. In contrast to the PDSI, the Z-index does not account for any persistence within the climate; rather, it characterizes the immediate (for a given week or month) conditions. The indices are calculated by computer programs available from the National Drought Mitigation Center and the Computer Science and Engineering Department, both located at the University of Nebraska-Lincoln. To allow for the assessment of climate change impacts, we modified the original computer code: the indices (which we named "relative" drought indices) are now calibrated using the present climate weather series and then applied to the future climate weather series. The resultant time series thus displays the drought conditions in terms of the present climate. The relative drought indices are applied to gridded (whole globe) GCM-simulated surface monthly weather series (available from the IPCC database), and the available water content is based on soil- texture-based water holding capacity global data developed by Webb et al. (1993, Global Biogeochem. Cycles 7: 97-108). The indices are calibrated with 1991-2020 period (considered to be the present climate) and then applied to two future periods: 2031-2060 and 2060-2099. To quantify impacts of climate change on the drought conditions, we analyze shifts in the grid-specific means of the drought indices and in the frequency of months belonging to drought spells. The drought spell is defined here as continuous periods in which the index does not exceed -1, and falls below -3 for at least one month. Results obtained by single GCMs

  11. Mechanisms of plant survival and mortality during drought: why do some plants survive while others succumb to drought?

    Science.gov (United States)

    McDowell, Nate G.; Pockman, William T.; Allen, Craig D.; Breshears, David D.; Cobb, Neil; Kolb, Thomas; Plaut, Jennifer; Sperry, John; West, Adam; Williams, David G.; Yepez, Enrico A.

    2008-01-01

    Severe droughts have been associated with regional-scale forest mortality worldwide. Climate change is expected to exacerbate regional mortality events; however, prediction remains difficult because the physiological mechanisms underlying drought survival and mortality are poorly understood. We developed a hydraulically based theory considering carbon balance and insect resistance that allowed development and examination of hypotheses regarding survival and mortality. Multiple mechanisms may cause mortality during drought. A common mechanism for plants with isohydric regulation of water status results from avoidance of drought-induced hydraulic failure via stomatal closure, resulting in carbon starvation and a cascade of downstream effects such as reduced resistance to biotic agents. Mortality by hydraulic failure per se may occur for isohydric seedlings or trees near their maximum height. Although anisohydric plants are relatively drought-tolerant, they are predisposed to hydraulic failure because they operate with narrower hydraulic safety margins during drought. Elevated temperatures should exacerbate carbon starvation and hydraulic failure. Biotic agents may amplify and be amplified by drought-induced plant stress. Wet multidecadal climate oscillations may increase plant susceptibility to drought-induced mortality by stimulating shifts in hydraulic architecture, effectively predisposing plants to water stress. Climate warming and increased frequency of extreme events will probably cause increased regional mortality episodes. Isohydric and anisohydric water potential regulation may partition species between survival and mortality, and, as such, incorporating this hydraulic framework may be effective for modeling plant survival and mortality under future climate conditions.

  12. Assessing future drought impacts on yields based on historical irrigation reaction to drought for four major crops in Kansas.

    Science.gov (United States)

    Zhang, Tianyi; Lin, Xiaomao

    2016-04-15

    Evaluation of how historical irrigation reactions can adapt to future drought is indispensable to irrigation policy, however, such reactions are poorly quantified. In this paper, county-level irrigation data for maize, soybean, grain sorghum, and wheat crops in Kansas were compiled. Statistical models were developed to quantify changes of irrigation and yields in response to drought for each crop. These were then used to evaluate the ability of current irrigation to cope with future drought impacts on each crop based on an ensemble Palmer Drought Severity Index (PDSI) prediction under the Representative Concentration Pathways 4.5 scenario. Results indicate that irrigation in response to drought varies by crop; approximately 10 to 13% additional irrigation was applied when PDSI was reduced by one unit for maize, soybean, and grain sorghum. However, the irrigation reaction for wheat exhibits a large uncertainty, indicating a weaker irrigation reaction. Analysis of future climate conditions indicates that maize, soybean, and grain sorghum yields would decrease 2.2-12.4% at the state level despite additional irrigation application induced by drought (which was expected to increase 5.1-19.0%), suggesting that future drought will exceed the range that historical irrigation reactions can adapt to. In contrast, a lower reduction (-0.99 to -0.63%) was estimated for wheat yields because wetter climate was projected in the central section of the study area. Expanding wheat areas may be helpful in avoiding future drought risks for Kansas agriculture.

  13. Integrated Nitrogen CAtchment model (INCA) applied to a tropical catchment in the Atlantic Forest, São Paulo, Brazil

    OpenAIRE

    Ranzini, M.; Forti, M. C.; Whitehead, P. G.; Arcova, F. C. S.; De Cicco, V.; Wade, A. J.

    2007-01-01

    Stream-water flows and in-stream nitrate and ammonium concentrations in a small (36.7 ha) Atlantic Forest catchment were simulated using the Integrated Nitrogen in CAtchments (INCA) model version 1.9.4. The catchment, at Cunha, is in the Serra do Mar State Park, SE Brazil and is nearly pristine because the nearest major conurbations, São Paulo and Rio, are some 450 km distant. However, intensive farming may increase nitrogen (N) deposition and there are growing pressures for urbanisation. The...

  14. A modeling of the carbon-nitrogen cycle transport at Igap\\'o I Lake - Londrina, Paran\\'a, Brazil

    CERN Document Server

    Pardo, Suellen Ribeiro; Romeiro, Neyva Maria Lopes; Cirilo, Eliandro Rodrigues

    2010-01-01

    This work is a contribution to better understand the effect that domestic sewage discharges may cause in a water body, specifically Igap\\'o I Lake, in Londrina, Paran\\'a, Brazil. The simulation of the dynamics of pollutant concentrations all over the water body is conducted by means of structured discretization of the geometry of Igap\\'o I Lake, together with the finite differences and the finite elements methods. Firstly, the hydrodynamic flow (without the pollutants), modeled by Navier-Stokes and pressure equations, is numerically resolved by the finite differences method, and associated with the fourth order Runge-Kutta procedure. After that, by using the hydrodynamic field velocity, the flow of the reactive species (pollutants) is described through a transport model, which considers advective and diffusive processes, as well as through a reactions model, restricted to the carbon-nitrogen cycle. The transport and reactions model is numerically resolved by the stabilized finite elements method, by means of ...

  15. Evaluation of the IPCC Models (AR4 and AR5) in the Precipitation Simulation in the Northeast of Brazil

    Science.gov (United States)

    Alves, José; Vasconcelos Junior, Francisco; Chaves, Rosane; Silva, Emerson; Servain, Jacques; Costa, Alexandre; Sombra, Sérgio; Barbosa, Augusto; Dos Santos, Antonio

    2016-04-01

    With the simulations of the models used in the latest reports from the Intergovernmental Panel on Climate Change (IPCC), comparative studies are necessary between observations and the so-called historical run (C20) and future projections of the AR4 (A2) and AR5 (RCP8.5) experiments, in order to assess whether the AR5 models had a better performance in the representation of physical processes. This article compares the sensitivity of IPCC models (AR4 and AR5) in representing the anuall average and seasonal rainfall variation (summer and autumn) in three regions of the Northeast of Brazil between 1979 and 2000, using the CMAP - CPC (Merged Analysis of Precipitation) data as reference. The projections made by these models for the period 2040-2070 were also analyzed.

  16. Evaluation of the IPCC Models (AR4 and AR5 in the Precipitation Simulation in the Northeast of Brazil

    Directory of Open Access Journals (Sweden)

    José Brabo Alves

    2016-04-01

    Full Text Available With the simulations of the models used in the latest reports from the Intergovernmental Panel on Climate Change (IPCC, comparative studies are necessary between observations and the so-called historical run (C20 and future projections of the AR4 (A2 and AR5 (RCP8.5 experiments, in order to assess whether the AR5 models had a better performance in the representation of physical processes. This article compares the sensitivity of IPCC models (AR4 and AR5 in representing the anuall average and seasonal rainfall variation (summer and autumn in three regions of the Northeast of Brazil between 1979 and 2000, using the CMAP - CPC (Merged Analysis of Precipitation data as reference. The projections made by these models for the period 2040-2070 were also analyzed.

  17. Adaptability analysis of the drought monitoring model based on the cloud parameters method in Africa%云参数法干旱遥感监测模型在非洲地区的适应性研究

    Institute of Scientific and Technical Information of China (English)

    张穗; 向大享; 孙忠华

    2013-01-01

    Firstly,the drought monitoring model based on CPI(Cloud Parameters Method/Index) is briefly introduced.Meanwhile,the characteristics of sensors,Spinning Enhanced Visible and Infra-Red Imager (SEVIRI),key payload of METAOSAT,are analyzed from the aspect for drought monitoring.Secondly,a suitable multi-spectral model is promoted to detect cloud pixels to calculate three cloud parameters.Then,the drought conditions of Africa in the winter of 2009 and spring of 2010 are monitored by using the cloud parameters method.Finally,the monitoring result is evaluated by comparing the monthly evaporation and monthly precipitation data from Climate Prediction Center,National Weather Service,US as reference data.The analysis indicated that the degree and scope of draught is almost same by comparing the monitoring results of CPI and area the reference data.Consequently,CPI is adaptable for the drought detecting in Africa.%从云参数法干旱遥感监测模型的需求角度分析了欧洲静止气象卫星SEVIRI数据的应用潜力,并提出了一种适合该数据的多光谱云检测方法;利用云参数法干旱遥感监测模型进行非洲地区2009年底和2010年初的干旱监测,以月度降水和蒸散数据作为参考数据评估监测结果.研究结果表明:云参数法监测结果与参考数据在干旱程度与范围方面基本一致,相对精度高达83.88%,云参数法适合进行非洲地区的干旱监测.

  18. System robustness analysis for drought risk management in South Florida

    Science.gov (United States)

    Eilander, D.; Bouwer, L.; Barnes, J.; Mens, M.; Obeysekera, J.

    2015-12-01

    Drought is a frequently returning natural hazard in Florida, with at least one severe drought to be expected every decade. These droughts have had many impacts such as loss of agricultural products, inadequate public water supply and salt water intrusion into freshwater aquifers. Furthermore, climate change projections for South Florida suggest that dry spells are likely to be more frequent and prolonged, with negative impacts on water supply management for all users. In this study a System Robustness Analysis was conducted in order to analyse the effectiveness of strategies to limit the socio-economic impact of droughts under climate change. System Robustness Analysis (SRA) aims to support decision making by quantifying how well a system, with and without additional measures, can remain functioning under a range of external disturbances. Two system characteristics add up to system robustness: Resistance is the ability to withstand disturbances without responding (zero impact), and resilience is the ability to recover from the response to a disturbance. SRA can help to provide insight into the sensitivity of a system to changing magnitudes of extreme weather events. A regional-scale hydrologic and water management model is used to simulate the effect of changing precipitation and evaporation forcing on agricultural and urban water supply and demand in South Florida. The complex water management operational rules including water use restrictions are simulated in the model. Based on model runs with a various climate scenarios, drought events with a wide range of severity are identified and for each event the socio-economic impacts are determined. Here, a drought is defined as a reduced streamflow in the upstream Kissimmee basin, which contributes most to Lake Okeechobee, the major surface water storage in the system. The drought severity is characterized by the maximum drought deficit volume. Drought impacts are analyzed for several users in Miami Dade County. From

  19. Southwestern USA Drought over Multiple Millennia

    Science.gov (United States)

    Salzer, M. W.; Kipfmueller, K. F.

    2014-12-01

    Severe to extreme drought conditions currently exist across much of the American West. There is increasing concern that climate change may be worsening droughts in the West and particularly the Southwest. Thus, it is important to understand the role of natural variability and to place current conditions in a long-term context. We present a tree-ring derived reconstruction of regional-scale precipitation for the Southwestern USA over several millennia. A network of 48 tree-ring chronologies from California, Nevada, Utah, Arizona, New Mexico, and Colorado was used. All of the chronologies are at least 1,000 years long. The network was subjected to data reduction through PCA and a "nested" multiple linear regression reconstruction approach. The regression model was able to capture 72% of the variance in September-August precipitation over the last 1,000 years and 53% of the variance over the first millennium of the Common Era. Variance captured and spatial coverage further declined back in time as the shorter chronologies dropped out of the model, eventually reaching 24% of variance captured at 3250 BC. Results show regional droughts on decadal- to multi-decadal scales have been prominent and persistent phenomena in the region over the last several millennia. Anthropogenic warming is likely to exacerbate the effects of future droughts on human and other biotic populations.

  20. Multi-level modeling of light-induced stomatal opening offers new insights into its regulation by drought.

    Science.gov (United States)

    Sun, Zhongyao; Jin, Xiaofen; Albert, Réka; Assmann, Sarah M

    2014-11-01

    Plant guard cells gate CO2 uptake and transpirational water loss through stomatal pores. As a result of decades of experimental investigation, there is an abundance of information on the involvement of specific proteins and secondary messengers in the regulation of stomatal movements and on the pairwise relationships between guard cell components. We constructed a multi-level dynamic model of guard cell signal transduction during light-induced stomatal opening and of the effect of the plant hormone abscisic acid (ABA) on this process. The model integrates into a coherent network the direct and indirect biological evidence regarding the regulation of seventy components implicated in stomatal opening. Analysis of this signal transduction network identified robust cross-talk between blue light and ABA, in which [Ca2+]c plays a key role, and indicated an absence of cross-talk between red light and ABA. The dynamic model captured more than 10(31) distinct states for the system and yielded outcomes that were in qualitative agreement with a wide variety of previous experimental results. We obtained novel model predictions by simulating single component knockout phenotypes. We found that under white light or blue light, over 60%, and under red light, over 90% of all simulated knockouts had similar opening responses as wild type, showing that the system is robust against single node loss. The model revealed an open question concerning the effect of ABA on red light-induced stomatal opening. We experimentally showed that ABA is able to inhibit red light-induced stomatal opening, and our model offers possible hypotheses for the underlying mechanism, which point to potential future experiments. Our modelling methodology combines simplicity and flexibility with dynamic richness, making it well suited for a wide class of biological regulatory systems.

  1. Probabilistic Drought Forecasting in Southern Taiwan Using El Niño-Southern Oscillation Index

    Directory of Open Access Journals (Sweden)

    Shien-Tsung Chen

    2013-01-01

    Full Text Available This study proposes a probabilistic drought forecasting model to forecast meteorological drought in Southern Taiwan using the El Niño-SouthernNiño-Southern Oscillation (ENSO index. Meteorological drought is defined by the standardized precipitation index (SPI, and the ENSO index is El NiñoNiño sea surface temperature (SST. Two probabilistic forecasting model architectures were constructed based on the transition probabilities from El NiñoNiño SSTs to SPIs. Both model architectures forecast a one-month-ahead probability distribution for meteorological drought using different combinations of El NiñoNiño SST variables. Forecasting results showed the robustness of the probabilistic drought forecasting models. In addition, this study discussed the selection of El NiñoNiño SST variables used in the probabilistic drought forecasting model, and found that models with a single SST input outperformed those with multiple SST inputs.

  2. Impact of drought on wildfires in Iberia

    Science.gov (United States)

    Russo, Ana; Gouveia, Célia M.; DaCamara, Carlos; Sousa, Pedro; Trigo, Ricardo M.

    2015-04-01

    months in August. In the Eastern and Northwestern regions the correlation was most significant for the SPI for 3 and 6 months. Thus, the relation between wildfires and drought is better explained in the Northern and Southwestern regions by the temperature influence and on the Northwestern and Eastern by the precipitation influence. Gouveia C.M., Bastos A., Trigo R.M., DaCamara C.C. (2012) "Drought impacts on vegetation in the pre and post-fire events over Iberian Peninsula". Natural Hazards and Earth System Sciences, 12, 3123-3137, 2012. Vicente-Serrano S.M., Santiago Beguería, Juan I. López-Moreno (2010) "A Multi-scalar drought index sensitive to global warming: The Standardized Precipitation Evapotranspiration Index - SPEI". Journal of Climate 23: 1696-1718. Trigo R.M., Sousa P., Pereira M., Rasilla D., Gouveia C.M. (2013) "Modelling wildfire activity in Iberia with different Atmospheric Circulation Weather Types". International Journal of Climatology, DOI: 10.1002/joc.3749 Sousa PM, Trigo RM, Pereira MG, Bedia J, Gutiérrez JM, 2014. Different approaches to model future burnt area in the Iberian Peninsula. Agricultural and Forest Meteorology 202, 11-25. doi:10.1016/j.agrformet.2014.11.018 Acknowledgements: This work was partially supported by national funds through FCT (Fundação para a Ciência e a Tecnologia, Portugal) under project QSECA (PTDC/AAGGLO/4155/2012).

  3. Drought in West Africa

    Science.gov (United States)

    2007-01-01

    Drought settled over West Africa's Ivory Coast region when wet season rains came late in 2007. Instead of beginning in February, the rainy season didn't start until March, and steady rains didn't start until late March, said the Famine Early Warning System Network. Though the rain had started to alleviate the drought, vegetation was still depressed in parts of Cote d'Ivoire (Ivory Coast) between March 22 and April 6, 2007, when the Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA's Terra satellite captured the data used to make this image. The image shows current vegetation conditions compared to average conditions recorded since 2000. Areas where plants are growing more slowly or more sparsely than average are brown, while areas where vegetation is denser than average are green. The brown tint that dominates the image indicates that plants through most of the country are more sparse than normal. Among the crops affected by the lack of rain was West Africa's cocoa crop. About 70 percent of the world's cocoa comes from West Africa, and Cote d'Ivoire is a top grower, said Reuters. Cocoa prices climbed as the crop fell short. Farmers called the drought the worst in living memory, Reuters said. The delay in rainfall also led to water shortages in parts of Cote d'Ivoire, according to the United Nations Office for the Coordination of Humanitarian Affairs.

  4. A Distributed Multi-dimensional SOLAP Model of Remote Sensing Data and Its Application in Drought Analysis

    OpenAIRE

    Li, Jiyuan; Meng, Lingkui; Cai, Yang; Zhang, Wen; Duan, Hongwei

    2014-01-01

    SOLAP (Spatial On-Line Analytical Processing) has been applied to multi-dimensional analysis of remote sensing data recently. However, its computation performance faces a considerable challenge from the large-scale dataset. A geo-raster cube model extended by Map-Reduce is proposed, which refers to the application of Map-Reduce (a data-intensive computing paradigm) in the OLAP field. In this model, the existing methods are modified to adapt to distributed environment based on the multi-level ...

  5. Modeling HIV/AIDS drug price determinants in Brazil: is generic competition a myth?

    Directory of Open Access Journals (Sweden)

    Constance Meiners

    Full Text Available BACKGROUND: Brazil became the first developing country to guarantee free and universal access to HIV/AIDS treatment, with antiretroviral drugs (ARVs being delivered to nearly 190,000 patients. The analysis of ARV price evolution and market dynamics in Brazil can help anticipate issues soon to afflict other developing countries, as the 2010 revision of the World Health Organization guidelines shifts demand towards more expensive treatments, and, at the same time, current evolution of international legislation and trade agreements on intellectual property rights may reduce availability of generic drugs for HIV care. METHODS AND FINDINGS: Our analyses are based on effective prices paid for ARV procurement in Brazil between 1996 and 2009. Data panel structure was exploited to gather ex-ante and ex-post information and address various sources of statistical bias. In-difference estimation offered in-depth information on ARV market characteristics which significantly influence prices. Although overall ARV prices follow a declining trend, changing characteristics in the generic segment help explain recent increase in generic ARV prices. Our results show that generic suppliers are more likely to respond to factors influencing demand size and market competition, while originator suppliers tend to set prices strategically to offset compulsory licensing threats and generic competition. SIGNIFICANCE: In order to guarantee the long term sustainability of access to antiretroviral treatment, our findings highlight the importance of preserving and stimulating generic market dynamics to sustain developing countries' bargaining power in price negotiations undertaken with originator companies.

  6. Validation of energy consumption forecasting model for the Brazil; Validacao de um modelo de previsao de consumo de energia para o Brasil

    Energy Technology Data Exchange (ETDEWEB)

    Duarte, Jose A.; Lima, Lutero C. de; Silva, Rui Pitanga M. da [Uberlandia Univ., MG (Brazil)

    1995-07-01

    A forecasting model for energy demand and consumption for Brazil has been adapted and developed from a model originally developed in the United States. Different forms of energetics were investigated and the results obtained shown good agreement with the historical data, available at the National Energy Balance.

  7. Drought analysis in middle Heihe River

    Institute of Scientific and Technical Information of China (English)

    Jin Junying; Zhang Zhenwei; Zhang Weihua

    2005-01-01

    Water shortage has become one of the severest problems in the middle Heihe River Basin because of high water demand but low available water supply. This paper is oriented to provide solutions to the problem through the analysis of drought. The main objectives to analyze the difference between water demand and supply in various water users in past, present (2000), and project (2010) situation, especially in agriculture, and the most important is to propose and assess a reasonable measure with the purpose of minimum drought and sustainable development. A simulation model, WAFLEX (Water Allocation Flow model in Excel) model is applied in this study to cope with water availability, distribution and requirement of various water users, and the result shows the model and the method is effective and feasible.

  8. Disentangling the contribution of multiple land covers to fire-mediated carbon emissions in Amazonia during the 2010 drought

    Science.gov (United States)

    Anderson, Liana Oighenstein; Aragão, Luiz E. O. C.; Gloor, Manuel; Arai, Egídio; Adami, Marcos; Saatchi, Sassan S.; Malhi, Yadvinder; Shimabukuro, Yosio E.; Barlow, Jos; Berenguer, Erika; Duarte, Valdete

    2015-10-01

    In less than 15 years, the Amazon region experienced three major droughts. Links between droughts and fires have been demonstrated for the 1997/1998, 2005, and 2010 droughts. In 2010, emissions of 510 ± 120 Tg C were associated to fire alone in Amazonia. Existing approaches have, however, not yet disentangled the proportional contribution of multiple land cover sources to this total. We develop a novel integration of multisensor and multitemporal satellite-derived data on land cover, active fires, and burned area and an empirical model of fire-induced biomass loss to quantify the extent of burned areas and resulting biomass loss for multiple land covers in Mato Grosso (MT) state, southern Amazonia—the 2010 drought most impacted region. We show that 10.77% (96,855 km2) of MT burned. We estimated a gross carbon emission of 56.21 ± 22.5 Tg C from direct combustion of biomass, with an additional 29.4 ± 10 Tg C committed to be emitted in the following years due to dead wood decay. It is estimated that old-growth forest fires in the whole Brazilian Legal Amazon (BLA) have contributed to 14.81 Tg of C (11.75 Tg C to 17.87 Tg C) emissions to the atmosphere during the 2010 fire season, with an affected area of 27,555 km2. Total C loss from the 2010 fires in MT state and old-growth forest fires in the BLA represent, respectively, 77% (47% to 107%) and 86% (68.2% to 103%) of Brazil's National Plan on Climate Change annual target for Amazonia C emission reductions from deforestation.

  9. Drought Forecasting Based on Machine Learning of Remote Sensing and Long-Range Forecast Data

    Science.gov (United States)

    Rhee, J.; Im, J.; Park, S.

    2016-06-01

    The reduction of drought impacts may be achieved through sustainable drought management and proactive measures against drought disaster. Accurate and timely provision of drought information is essential. In this study, drought forecasting models to provide high-resolution drought information based on drought indicators for ungauged areas were developed. The developed models predict drought indices of the 6-month Standardized Precipitation Index (SPI6) and the 6-month Standardized Precipitation Evapotranspiration Index (SPEI6). An interpolation method based on multiquadric spline interpolation method as well as three machine learning models were tested. Three machine learning models of Decision Tree, Random Forest, and Extremely Randomized Trees were tested to enhance the provision of drought initial conditions based on remote sensing data, since initial conditions is one of the most important factors for drought forecasting. Machine learning-based methods performed better than interpolation methods for both classification and regression, and the methods using climatology data outperformed the methods using long-range forecast. The model based on climatological data and the machine learning method outperformed overall.

  10. DROUGHT FORECASTING BASED ON MACHINE LEARNING OF REMOTE SENSING AND LONG-RANGE FORECAST DATA

    Directory of Open Access Journals (Sweden)

    J. Rhee

    2016-06-01

    Full Text Available The reduction of drought impacts may be achieved through sustainable drought management and proactive measures against drought disaster. Accurate and timely provision of drought information is essential. In this study, drought forecasting models to provide high-resolution drought information based on drought indicators for ungauged areas were developed. The developed models predict drought indices of the 6-month Standardized Precipitation Index (SPI6 and the 6-month Standardized Precipitation Evapotranspiration Index (SPEI6. An interpolation method based on multiquadric spline interpolation method as well as three machine learning models were tested. Three machine learning models of Decision Tree, Random Forest, and Extremely Randomized Trees were tested to enhance the provision of drought initial conditions based on remote sensing data, since initial conditions is one of the most important factors for drought forecasting. Machine learning-based methods performed better than interpolation methods for both classification and regression, and the methods using climatology data outperformed the methods using long-range forecast. The model based on climatological data and the machine learning method outperformed overall.

  11. Modeling the impact of drought on canopy carbon and water fluxes through parameter optimization using an ensemble Kalman filter

    Directory of Open Access Journals (Sweden)

    W. Ju

    2009-08-01

    Full Text Available Soil and atmospheric water deficits have significant influences on CO2 and energy exchanges between the atmosphere and terrestrial ecosystems. Model parameterization significantly affects the ability of a model to simulate carbon, water, and energy fluxes. In this study, an ensemble Kalman filter (EnKF and observations of gross primary productivity (GPP and latent heat (LE fluxes were used to optimize model parameters significantly affecting the calculation of these fluxes for a subtropical coniferous plantation in southeastern China. The optimized parameters include the maximum carboxylation rate (Vcmax, the Ball-Berry coefficient (m and the coefficient determining the sensitivity of stomatal conductance to atmospheric water vapor deficit D0. Optimized Vcmax and m showed larger seasonal and interannual variations than D0. Seasonal variations of Vcmax and m are more pronounced than the interannual variations. Vcmax and m are associated with soil water content (SWC. During dry periods, SWC at the 20 cm depth can explain 61% and 64% of variations of Vcmax and m, respectively. EnKF parameter optimization improves the simulations of GPP, LE and sensible heat (SH, mainly during dry periods. After parameter optimization using EnKF, the variations of GPP, LE and SH explained by the model increased by 1% to 4% at half-hourly steps and by 3% to 5% at daily time steps. Efforts are needed to develop algorithms that can properly describe the variations of these parameters under different environmental conditions.

  12. Multilevel and multiscale drought reanalysis over France with the Safran-Isba-Modcou hydrometeorological suite

    Directory of Open Access Journals (Sweden)

    J.-P. Vidal

    2010-03-01

    Full Text Available Physically-based droughts can be defined as a water deficit in at least one component of the land surface hydrological cycle. The reliance of different activity domains (water supply, irrigation, hydropower, etc. on specific components of this cycle requires drought monitoring to be based on indices related to meteorological, agricultural, and hydrological droughts. This paper describes a high-resolution retrospective analysis of such droughts in France over the last fifty years, based on the Safran-Isba-Modcou (SIM hydrometeorological suite. The high-resolution 1958–2008 Safran atmospheric reanalysis was used to force the Isba land surface scheme and the hydrogeological model Modcou. Meteorological droughts are characterized with the Standardized Precipitation Index (SPI at time scales varying from 1 to 24 months. Similar standardizing methods were applied to soil moisture and streamflow for identifying multiscale agricultural droughts – through the Standardized Soil Wetness Index (SSWI – and multiscale hydrological droughts, through the Standardized Flow Index (SFI. Based on a common threshold level for all indices, drought event statistics over the 50-yr period – number of events, duration, severity and magnitude – have been derived locally in order to highlight regional differences at multiple time scales and at multiple levels of the hydrological cycle (precipitation, soil moisture, streamflow. Results show a substantial variety of temporal drought patterns over the country that are highly dependent on both the variable and time scale considered. Independent spatio-temporal drought events have then been identified and described by combining local characteristics with the evolution of area under drought. Summary statistics have finally been used to compare past severe drought events, from multi-year precipitation deficits (1989–1990 to short hot and dry periods (2003. Results show that the ranking of drought events depends highly

  13. Synthetic drought event sets: thousands of meteorological drought events for risk-based management under present and future conditions

    Science.gov (United States)

    Guillod, Benoit P.; Massey, Neil; Otto, Friederike E. L.; Allen, Myles R.; Jones, Richard; Hall, Jim W.

    2016-04-01

    Droughts and related water scarcity can have large impacts on societies and consist of interactions between a number of natural and human factors. Meteorological conditions are usually the first natural trigger of droughts, and climate change is expected to impact these and thereby the frequency and intensity of the events. However, extreme events such as droughts are, by definition, rare, and accurately quantifying the risk related to such events is therefore difficult. The MaRIUS project (Managing the Risks, Impacts and Uncertainties of drought and water Scarcity) aims at quantifying the risks associated with droughts in the UK under present and future conditions. To do so, a large number of drought events, from climate model simulations downscaled at 25km over Europe, are being fed into hydrological models of various complexity and used for the estimation of drought risk associated with human and natural systems, including impacts on the economy, industry, agriculture, terrestrial and aquatic ecosystems, and socio-cultural aspects. Here, we present the hydro-meteorological drought event set that has been produced by weather@home [1] for MaRIUS. Using idle processor time on volunteers' computers around the world, we have run a very large number (10'000s) of Global Climate Model (GCM) simulations, downscaled at 25km over Europe by a nested Regional Climate Model (RCM). Simulations include the past 100 years as well as two future horizons (2030s and 2080s), and provide a large number of sequences of spatio-temporally consistent weather, which are consistent with the boundary forcing such as the ocean, greenhouse gases and solar forcing. The drought event set for use in impact studies is constructed by extracting sequences of dry conditions from these model runs, leading to several thousand drought events. In addition to describing methodological and validation aspects of the synthetic drought event sets, we provide insights into drought risk in the UK, its

  14. Assessment of Trends of Drought in China from CMIP5

    Science.gov (United States)

    Yang, Xiaoli; Ren, Liliang; Liu, Yi; Ma, Mingwei; Cheng, Xuerong; Jiang, Shanhu; Yuan, Fei

    2015-04-01

    Droughts are becoming the most expensive natural disasters in China and have exerted serious impacts on local economic development and ecological environment. With the global warming, the frequency and density of drought are showing increasing over China. The fifth phase of the Coupled Model Intercomparison Project (CMIP5) shows that the temperature will increasing about 0.7°C/10 annual and the area-averaged annual mean precipitation will be increasing under highest RCP scenarios. The main objective of this study is to evaluate the drought trends with the estimation of the Palmer Drought Severity Index (PDSI) and Soil Moisture Index (SMI) in the future over China. In order to do this, the downscaled precipitation and temperature time series from CMIP5 are used as input forcing data of the Variable Infiltration Capacity (VIC) model. The Change trends and temporal-spatial characteristics of the simulation results from the CMIP5 models and VIC model are analyzed over seven climate regions as well as at whole country level. The trends of drought in 21st century over China based on the PDSI is analyzed with the output of CMIP5 models from 1950 to 2099. The SMI is estimated from the VIC soil moisture simulation with a spatial resolution of 0.5°×0.5° from 1950 to 2099, which is forced by the statistics downscaled output of CMIP5 models. The Mann-Kendall (MK) method is used to analyzing the trends of drought occurrence in seven climate regions and whole China. The results show that the drought will be more seriously in the 21st century than that in 20th century over the whole China with the increasing of temperature. Furthermore, most areas of China will become drier in 21st century baesd on the analysis results of PDSI and SMI. Especially, southwest of China is projected to experience more severe drought in the future than any other part of China.

  15. Drought effects on biomass production and radiation-use efficiency in barley

    International Nuclear Information System (INIS)

    Changes in biomass production of a barley crop in response to droughts of various timing and duration were analysed using a simple radiation interception model. Decreased growth rates were caused primarily by reductions in radiation-use efficiency when drought was imposed from emergence. In these treatments radiation-use efficiency was depressed even after drought was relieved. In contrast, in treatments where drought was imposed from two weeks before anthesis or later, the primary cause of reduced biomass production was a decrease in the amount of radiation intercepted, mostly associated with more rapid leaf senescence. For the later drought treatments, the radiation-use efficiency was stable and near the maximum value for unstressed crops. However, final biomass was sensitive to drought timing and, in particular, was more sensitive to maximum potential soil moisture deficit for the early than the later drought treatments. (author)

  16. Vegetation Drought Response Index: 2010-Present

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — VegDRI, short for Vegetation Drought Response Index, is a drought-monitoring tool developed by scientists at EROS in collaboration with the National Drought...

  17. Assessing various drought indicators in representing drought in boreal forests in Finland

    Science.gov (United States)

    Gao, Y.; Markkanen, T.; Thum, T.; Aurela, M.; Lohila, A.; Mammarella, I.; Hagemann, S.; Aalto, T.

    2015-08-01

    Droughts can impact on forest functioning and production, and even lead to tree mortality. However, drought is an elusive phenomenon that is difficult to quantify and define universally. In this study, we assessed the performance of a set of indicators that have been used to describe drought conditions in the summer months (June, July, August) over a 30 year period (1981-2010) in Finland. Those indicators include the Standardized Precipitation Index (SPI), the Standardized Precipitation-Evapotranspiration Index (SPEI), the Soil Moisture Index (SMI) and the Soil Moisture Anomaly (SMA). Herein, regional soil moisture was produced by the land surface model JSBACH. While SPI, SPEI, and SMA show a degree of anomalies from the statistical means over a period, SMI is directly connected to plant available water and closely dependent on soil properties. Moreover, the buffering effect of soil moisture and the associated soil moisture memory can impact on the onset and duration of drought as indicated by the SMI and SMA, whereas SPI and SPEI are directly controlled by meteorological conditions. In particular, we investigated whether the SMI, SMA and SPEI are able to indicate the Extreme Drought affecting Forest health (EDF) in Finland. EDF thresholds for these indicators are suggested, based on the spatially representative statistics of forest health observations in the exceptional dry year 2006. Our results showed that SMI was the best indicator in capturing the spatial extent of forest damage induced by the extreme drought in 2006. In addition, the derived thresholds were applied to those indicators to capture EDF events over the summer months of the 30 year study period. The SPEI and SMA showed more frequent EDF events over the 30 year period, and typically described a higher fraction of influenced area than SMI. In general, the suggested EDF thresholds for those indicators may be used for the indication of EDF events in Finland or other boreal forests areas in the context

  18. Assessing various drought indicators in representing drought in boreal forests in Finland

    Directory of Open Access Journals (Sweden)

    Y. Gao

    2015-08-01

    Full Text Available Droughts can impact on forest functioning and production, and even lead to tree mortality. However, drought is an elusive phenomenon that is difficult to quantify and define universally. In this study, we assessed the performance of a set of indicators that have been used to describe drought conditions in the summer months (June, July, August over a 30 year period (1981–2010 in Finland. Those indicators include the Standardized Precipitation Index (SPI, the Standardized Precipitation–Evapotranspiration Index (SPEI, the Soil Moisture Index (SMI and the Soil Moisture Anomaly (SMA. Herein, regional soil moisture was produced by the land surface model JSBACH. While SPI, SPEI, and SMA show a degree of anomalies from the statistical means over a period, SMI is directly connected to plant available water and closely dependent on soil properties. Moreover, the buffering effect of soil moisture and the associated soil moisture memory can impact on the onset and duration of drought as indicated by the SMI and SMA, whereas SPI and SPEI are directly controlled by meteorological conditions. In particular, we investigated whether the SMI, SMA and SPEI are able to indicate the Extreme Drought affecting Forest health (EDF in Finland. EDF thresholds for these indicators are suggested, based on the spatially representative statistics of forest health observations in the exceptional dry year 2006. Our results showed that SMI was the best indicator in capturing the spatial extent of forest damage induced by the extreme drought in 2006. In addition, the derived thresholds were applied to those indicators to capture EDF events over the summer months of the 30 year study period. The SPEI and SMA showed more frequent EDF events over the 30 year period, and typically described a higher fraction of influenced area than SMI. In general, the suggested EDF thresholds for those indicators may be used for the indication of EDF events in Finland or other boreal forests

  19. Hydrological drought types in cold climates

    OpenAIRE

    Loon, van, R.R.; S. W. Ploum; Parajka, J.; A. K. Fleig; Garnier, E.; Laaha, G.; Lanen, van, H.A.J.

    2015-01-01

    For drought management and prediction, knowledge of causing factors and socio-economic impacts of hydrological droughts is crucial. Propagation of meteorological conditions in the hydrological cycle results in different hydrological drought types that require separate analysis. In addition to the existing hydrological drought typology, we here define two new drought types related to snow and ice. A snowmelt drought is a deficiency in the snowmelt discharge peak in spring in snow-influenced ba...

  20. Probabilistic analysis of hydrological drought characteristics using meteorological drought

    NARCIS (Netherlands)

    Wong, G.; Lanen, van H.A.J.; Torfs, P.J.J.F.

    2013-01-01

    Droughts are an inevitable consequence of climate variability and are pervasive across many regions. Their effects can vary on an extensive scale, depending on the type of drought and people’s vulnerability. Crucial characteristics of both hydrological (groundwater, streamflow) and meteorological (p

  1. A comprehensive framework for tourism and recreation drought vulnerability reduction

    International Nuclear Information System (INIS)

    The effects of drought are vast, but loss statistics often do not reflect the impacts on the tourism and recreation sector, which for many places is one of the most critical economic drivers. This is concerning because drought events are common across the globe, with varying frequency, duration, and intensity, and are therefore unavoidable. Over the years, drought conditions have been at record levels in many regions, causing deep societal and economic impacts. However, little research has been conducted on connections between tourism/recreation and drought, revealing a distinct disconnect between the tourism/recreation sector and drought management. To bridge this gap in the current understanding of, and approaches to, managing drought in the tourism/recreation sector, we present an interdisciplinary conceptual framework that integrates tourism/recreation into the drought management process to ensure sustainable economic development and community vitality. The model presented here promotes understanding of critical interactions through a bottom-up stakeholder engagement process balanced with formal top-down management approaches. (letter)

  2. A comprehensive framework for tourism and recreation drought vulnerability reduction

    Science.gov (United States)

    Thomas, Deborah S. K.; Wilhelmi, Olga V.; Finnessey, Taryn N.; Deheza, Veva

    2013-12-01

    The effects of drought are vast, but loss statistics often do not reflect the impacts on the tourism and recreation sector, which for many places is one of the most critical economic drivers. This is concerning because drought events are common across the globe, with varying frequency, duration, and intensity, and are therefore unavoidable. Over the years, drought conditions have been at record levels in many regions, causing deep societal and economic impacts. However, little research has been conducted on connections between tourism/recreation and drought, revealing a distinct disconnect between the tourism/recreation sector and drought management. To bridge this gap in the current understanding of, and approaches to, managing drought in the tourism/recreation sector, we present an interdisciplinary conceptual framework that integrates tourism/recreation into the drought management process to ensure sustainable economic development and community vitality. The model presented here promotes understanding of critical interactions through a bottom-up stakeholder engagement process balanced with formal top-down management approaches.

  3. Diurnal oscillations of soybean circadian clock and drought responsive genes.

    Directory of Open Access Journals (Sweden)

    Juliana Marcolino-Gomes

    Full Text Available Rhythms produced by the endogenous circadian clock play a critical role in allowing plants to respond and adapt to the environment. While there is a well-established regulatory link between the circadian clock and responses to abiotic stress in model plants, little is known of the circadian system in crop species like soybean. This study examines how drought impacts diurnal oscillation of both drought responsive and circadian clock genes in soybean. Drought stress induced marked changes in gene expression of several circadian clock-like components, such as LCL1-, GmELF4- and PRR-like genes, which had reduced expression in stressed plants. The same conditions produced a phase advance of expression for the GmTOC1-like, GmLUX-like and GmPRR7-like genes. Similarly, the rhythmic expression pattern of the soybean drought-responsive genes DREB-, bZIP-, GOLS-, RAB18- and Remorin-like changed significantly after plant exposure to drought. In silico analysis of promoter regions of these genes revealed the presence of cis-elements associated both with stress and circadian clock regulation. Furthermore, some soybean genes with upstream ABRE elements were responsive to abscisic acid treatment. Our results indicate that some connection between the drought response and the circadian clock may exist in soybean since (i drought stress affects gene expression of circadian clock components and (ii several stress responsive genes display diurnal oscillation in soybeans.

  4. Multiyear drought-induced morbidity preceding tree death in southeastern U.S. forests.

    Science.gov (United States)

    Berdanier, Aaron B; Clark, James S

    2016-01-01

    Recent forest diebacks, combined with threats of future drought, focus attention on the extent to which tree death is caused by catastrophic events as opposed to chronic declines in health that accumulate over years. While recent attention has focused on large-scale diebacks, there is concern that increasing drought stress and chronic morbidity may have pervasive impacts on forest composition in many regions. Here we use long-term, whole-stand inventory data from southeastern U.S. forests to show that trees exposed to drought experience multiyear declines in growth prior to mortality. Following a severe, multiyear drought, 72% of trees that did not recover their pre-drought growth rates died within 10 yr. This pattern was mediated by local moisture availability. As an index of morbidity prior to death, we calculated the difference in cumulative growth after drought relative to surviving conspecifics. The strength of drought-induced morbidity varied among species and was correlated with drought tolerance. These findings support the ability of trees to avoid death during drought events but indicate shifts that could occur over decades. Tree mortality following drought is predictable in these ecosystems based on growth declines, highlighting an opportunity to address multiyear drought-induced morbidity in models, experiments, and management decisions.

  5. Identification and comparative analysis of drought-associated microRNAs in two cowpea genotypes

    Directory of Open Access Journals (Sweden)

    Roberts Philip A

    2011-09-01

    Full Text Available Abstract Background Cowpea (Vigna unguiculata is an important crop in arid and semi-arid regions and is a good model for studying drought tolerance. MicroRNAs (miRNAs are known to play critical roles in plant stress responses, but drought-associated miRNAs have not been identified in cowpea. In addition, it is not understood how miRNAs might contribute to different capacities of drought tolerance in different cowpea genotypes. Results We generated deep sequencing small RNA reads from two cowpea genotypes (CB46, drought-sensitive, and IT93K503-1, drought-tolerant that grew under well-watered and drought stress conditions. We mapped small RNA reads to cowpea genomic sequences and identified 157 miRNA genes that belong to 89 families. Among 44 drought-associated miRNAs, 30 were upregulated in drought condition and 14 were downregulated. Although miRNA expression was in general consistent in two genotypes, we found that nine miRNAs were predominantly or exclusively expressed in one of the two genotypes and that 11 miRNAs were drought-regulated in only one genotype, but not the other. Conclusions These results suggest that miRNAs may play important roles in drought tolerance in cowpea and may be a key factor in determining the level of drought tolerance in different cowpea genotypes.

  6. Multiyear drought-induced morbidity preceding tree death in southeastern U.S. forests.

    Science.gov (United States)

    Berdanier, Aaron B; Clark, James S

    2016-01-01

    Recent forest diebacks, combined with threats of future drought, focus attention on the extent to which tree death is caused by catastrophic events as opposed to chronic declines in health that accumulate over years. While recent attention has focused on large-scale diebacks, there is concern that increasing drought stress and chronic morbidity may have pervasive impacts on forest composition in many regions. Here we use long-term, whole-stand inventory data from southeastern U.S. forests to show that trees exposed to drought experience multiyear declines in growth prior to mortality. Following a severe, multiyear drought, 72% of trees that did not recover their pre-drought growth rates died within 10 yr. This pattern was mediated by local moisture availability. As an index of morbidity prior to death, we calculated the difference in cumulative growth after drought relative to surviving conspecifics. The strength of drought-induced morbidity varied among species and was correlated with drought tolerance. These findings support the ability of trees to avoid death during drought events but indicate shifts that could occur over decades. Tree mortality following drought is predictable in these ecosystems based on growth declines, highlighting an opportunity to address multiyear drought-induced morbidity in models, experiments, and management decisions. PMID:27039506

  7. Distinguishing warming-induced drought from drought-induced warming

    Science.gov (United States)

    Roderick, M. L.; Yin, D.

    2015-12-01

    It is usually observed that temperatures, especially maximum temperatures are higher during drought. A very widely held public perception is that the increase in temperature is a cause of drought. This represents the warming-induced drought scenario. However, the agricultural and hydrologic scientific communities have a very different interpretation with drought being the cause of increasing temperature. In essence, those communities assume the warming is a surface feedback and their interpretation is for drought-induced warming. This is a classic cause-effect problem that has resisted definitive explanation due to the lack of radiative observations at suitable spatial and temporal scales. In this presentation we first summarise the observations and then use theory to untangle the cause-effect relationships that underlie the competing interpretations. We then show how satellite data (CERES, NASA) can be used to disentangle the cause-effect relations.

  8. Erosivity, surface runoff, and soil erosion estimation using GIS-coupled runoff-erosion model in the Mamuaba catchment, Brazil.

    Science.gov (United States)

    Marques da Silva, Richarde; Guimarães Santos, Celso Augusto; Carneiro de Lima Silva, Valeriano; Pereira e Silva, Leonardo

    2013-11-01

    This study evaluates erosivity, surface runoff generation, and soil erosion rates for Mamuaba catchment, sub-catchment of Gramame River basin (Brazil) by using the ArcView Soil and Water Assessment Tool (AvSWAT) model. Calibration and validation of the model was performed on monthly basis, and it could simulate surface runoff and soil erosion to a good level of accuracy. Daily rainfall data between 1969 and 1989 from six rain gauges were used, and the monthly rainfall erosivity of each station was computed for all the studied years. In order to evaluate the calibration and validation of the model, monthly runoff data between January 1978 and April 1982 from one runoff gauge were used as well. The estimated soil loss rates were also realistic when compared to what can be observed in the field and to results from previous studies around of catchment. The long-term average soil loss was estimated at 9.4 t ha(-1) year(-1); most of the area of the catchment (60%) was predicted to suffer from a low- to moderate-erosion risk (catchment, the soil erosion was estimated to exceed > 12 t ha(-1) year(-1). Expectedly, estimated soil loss was significantly correlated with measured rainfall and simulated surface runoff. Based on the estimated soil loss rates, the catchment was divided into four priority categories (low, moderate, high and very high) for conservation intervention. The study demonstrates that the AvSWAT model provides a useful tool for soil erosion assessment from catchments and facilitates the planning for a sustainable land management in northeastern Brazil. PMID:23652539

  9. A European Drought Reference Database: Design and Online Implementation

    NARCIS (Netherlands)

    Stagge, J.H.; Tallaksen, L.M.; Kohn, I.; Stahl, K.; Loon, van A.

    2013-01-01

    This report presents the structure and status of the online European Drought Reference (EDR) database. This website provides detailed historical information regarding major historical European drought events. Each drought event is summarized using climatological drought indices, hydrological drought

  10. Numerical model to evaluate the mitigation strategies to combat desertification and drought in the arid land of northern Chile.

    Science.gov (United States)

    Salinas, Carla; Mendieta, Jon

    2014-05-01

    Desertification is considered a global environmental problem with political and socioeconomic implications. Desertification, exacerbated by climate change, is the largest environmental problem in Chile affecting almost two third of the national territory. This study takes place in a latitudinal gradient of the north-central Chilean drylands, where desertification is a threat to agriculture, livestock and forestry (ALF). The critical areas or priority areas for combating desertification are the northernmost areas of the region under study. In the context of the United Nations Convention to Combat Desertification (UNCCD) and the implementation of the Chilean National Action Programme (NAP), the country is conducting policies and investing in mitigation strategies to combat land degradation and desertification. The main objective of this study is the development of an integrative methodological approach using real data of the territorial and socioeconomic indicators. With the proposed methodology we assess the impact of the mitigation and land degradation strategies supported by the ALF promotion agencies in the fight against desertification, projecting different scenarios of change. The data were collected in 2008 in Santiago, Chile. The results of the Principal Component Analysis (PCA) suggest that technical irrigation and the improvement of grasslands and pastures play an important role in the fight against desertification. The results of the model projections are consistent, suggesting that the efforts of the ALF promotion agencies have a positive impact in fighting desertification. Inaction of ALF mitigation strategies would increase desertification. This methodological approach, performed with real data, can also determine the main causes of desertification in such a complex area as the studied one, where we can find the desert itself, and its desertification endangered valleys, the Andean plateau, the transitional area and the southern regions. Ii is also a

  11. Root niche separation can explain avoidance of seasonal drought stress and vulnerability of overstory trees to extended drought in a mature Amazonian forest

    Science.gov (United States)

    Ivanov, Valeriy Y.; Hutyra, Lucy R.; Wofsy, Steven C.; Munger, J. William; Saleska, Scott R.; de Oliveira, Raimundo C., Jr.; de Camargo, Plínio B.

    2012-12-01

    Large areas of Amazonian evergreen forest experience seasonal droughts extending for three or more months, yet show maximum rates of photosynthesis and evapotranspiration during dry intervals. This apparent resilience is belied by disproportionate mortality of the large trees in manipulations that reduce wet season rainfall, occurring after 2-3 years of treatment. The goal of this study is to characterize the mechanisms that produce these contrasting ecosystem responses. A mechanistic model is developed based on the ecohydrological framework of TIN (Triangulated Irregular Network)-based Real Time Integrated Basin Simulator + Vegetation Generator for Interactive Evolution (tRIBS+VEGGIE). The model is used to test the roles of deep roots and soil capillary flux to provide water to the forest during the dry season. Also examined is the importance of "root niche separation," in which roots of overstory trees extend to depth, where during the dry season they use water stored from wet season precipitation, while roots of understory trees are concentrated in shallow layers that access dry season precipitation directly. Observational data from the Tapajós National Forest, Brazil, were used as meteorological forcing and provided comprehensive observational constraints on the model. Results strongly suggest that deep roots with root niche separation adaptations explain both the observed resilience during seasonal drought and the vulnerability of canopy-dominant trees to extended deficits of wet season rainfall. These mechanisms appear to provide an adaptive strategy that enhances productivity of the largest trees in the face of their disproportionate heat loads and water demand in the dry season. A sensitivity analysis exploring how wet season rainfall affects the stability of the rainforest system is presented.

  12. UPDATE July 2012 | The Food Crises: The US Drought

    OpenAIRE

    Marco Lagi; Yavni Bar-Yam; Yaneer Bar-Yam

    2012-01-01

    Recent droughts in the midwestern United States threaten to cause global catastrophe driven by a speculator amplified food price bubble. Here we show the effect of speculators on food prices using a validated quantitative model that accurately describes historical food prices. During the last six years, high and fluctuating food prices have lead to widespread hunger and social unrest. While a relative dip in food prices occurred during the spring of 2012, a massive drought in the American Mid...

  13. Monte Carlo approach to assess the uncertainty of wide-angle layered models: Application to the Santos Basin, Brazil

    Science.gov (United States)

    Loureiro, Afonso; Afilhado, Alexandra; Matias, Luís; Moulin, Maryline; Aslanian, Daniel

    2016-06-01

    In the Santos Basin (Brazil), two parallel wide-angle refraction profiles show different crustal structures. One shows moderate crustal velocity gradient, and a clear Moho with topography. The other has an anomalous velocity zone, and no clear Moho reflections. This has large implications on the geological and geodynamical interpretation of the basin. Model uncertainties must be excluded as a source of these differences. We developed VMONTECARLO, a tool to assess model uncertainty of layered velocity models using a Monte Carlo approach and simultaneous parameter perturbation using all picked refracted and reflected arrivals. It gives insights into the acceptable geological interpretations allowed by data and model uncertainty through velocity-depth plots that provide: a) the velocity-depth profile range that is consistent with the travel times; b) the random model that provides the best fit, keeping most of the observations covered by ray-tracing; c) insight into valid models dispersion; d) main model features unequivocally required by the travel times, e.g., first-order versus second-order discontinuities, and velocity gradient magnitudes; e) parameter value probability distribution histograms. VMONTECARLO is seamlessly integrated into a RAYINVR-based modelling work-flow, and can be used to assess final models or sound the solution space for alternate models, and is also capable of evaluating forward models without the need for inversion, thus avoiding local minima that may trap the inversion algorithms and providing information for models still not well-parametrised. Results for the Brazilian models show that the imaged structures are indeed geologically different and are not due to different interpretations of the same features within the model uncertainty bounds. These differences highlight the strong heterogeneity of the crust in the middle of the Santos Basin, where the rift is supposed to have failed.

  14. Geomorphic response to historic drought in northern California

    Science.gov (United States)

    Bennett, Georgina; Roering, Joshua; Mackey, Ben; Handwerger, Alexander; Guillod, Benoit; Schmidt, David

    2016-04-01

    California declared a state of drought emergency in early 2014 with a recent study showing that 2012 - 2015 constitutes a drought unprecedented in the state's historical record. Much has been reported on the drought's devastating impacts on water supply, agriculture and wildfire occurrence as well as its possible origins, including the role of anthropogenic climate change. However, its geomorphic impact has been given little attention. We address this gap by assessing the response of earthflows to drought in the Eel River in northern California. Despite their slow-moving nature, earthflows contribute ~50% of erosion in the region and are a constant threat to transport routes, making their behavior important to understand. We used pixel tracking in the program COSI CORR to measure velocities of 98 earthflows for the periods 2009 - 2012 and 2012 - 2015 from 0.5 m resolution Worldview satellite imagery. Putting these measurements in the context of velocities manually measured from aerial photographs dating back to the 1950s indicates that whilst earthflows have decelerated significantly in the ensuing drought this is part of a slowing trend commencing around 2000. We show that decadal earthflow velocities are closely correlated with the Palmer Drought Severity Index (PDSI), which in turn is correlated with North American Land Data Assimilation System (NLDAS)-modeled soil moisture. Slowing of earthflows since 2000 is coincident with a reduction of soil moisture, starting with the 2000 - 2001 drought from which earthflows have not yet returned to their pre-drought values and which set the stage for the slowest mean velocities observed in recent decades during the current drought. It will be important to continue to monitor these earthflows as rains return, particularly given the hypothesis that extreme drying may increase pathways for future runoff into earthflows.

  15. Soil microbiology under drought stress

    Science.gov (United States)

    he severity of the 2012 drought affecting much of the Midwestern U.S. is readily observed in the extremely stressed conditions of crops and natural vegetation. However, we may not realize that the extent of drought effects is just as severe on the biology below the soil surface. Detrimental effects ...

  16. Distinguishing drought and water scarcity

    NARCIS (Netherlands)

    Loon, van A.

    2013-01-01

    Water resources can become strained by both natural factors such as drought and human factors such as unsustainable use. Water resource managers can develop practices to reduce overuse of water resources, but they cannot prevent droughts, so distinguishing the causes of water stress can be useful. H

  17. Drought over China in the 21st Century: Results of RegCM3%Drought over China in the 21st Century: Results of RegCM3

    Institute of Scientific and Technical Information of China (English)

    LIU Ke; JIANG Da-Bang; MA Jian-Yong

    2012-01-01

    Based on 150-year simulations of a regional climate model, RegCM3, under the Special Report on Emissions Scenarios (SRES) A1B scenario, the effective drought index (EDI) is used to project the future drought change in China. During the baseline period 1986–2005, RegCM3 was found to reliably simulate the spatial pattern of drought over the country. Over the 21st century, the regionally averaged EDI should increase, corresponding to a decrease of drought, while the probability of extreme drought events should increase. Geographically, drought should clearly increase in Northeast China, the middle and lower reaches of the Yangtze River valley, Southwest China, and southern Tibet but decrease in most parts of the rest of the country.

  18. Past and future hydrological drought in water-scarce European regions

    Science.gov (United States)

    Van Lanen, Henny A. J.; Van Loon, Anne F.; Van Huijgevoort, Marjolein H. J.; Wanders, Niko; Alderlieste, Marcel A. A.; Stahl, Kerstin; Tallaksen, Lena M.

    2013-04-01

    In many Mediterranean regions water resources are heavily exploited leading to water scarcity. Global change likely will worsen water scarcity. This is particularly felt during drought. Therefore, drought should be explicitly addressed in water resources assessments. IPCC states that lack of hydrological data, multiple definitions, imperfect knowledge on drought-generating processes, and the imperfectness of models impede high confidence in drought assessments. This study addresses trends in past and future drought with focus on the Mediterranean region. We argue that, for water resources assessment, hydrological drought needs to be investigated instead of the more often used meteorological drought. This implies that drought propagation should be considered, incl. non-linearities due to temperature-related and storage-related processes resulting in different hydrological drought types, which have different impacts on water resources. Drought and water scarcity are closely linked and complex interrelationships exist. Trend studies on past drought, however, require that the two phenomena are separated. An innovative observational-modelling approach is presented that, through a combined flow naturalisation and analysis of anomalies, distinguishes between water scarcity and drought. We investigated trends in observed low flows (for near-natural catchments in southern Europe) and trends in hydrological drought characteristics (for other selected Mediterranean study areas), which were obtained from multi-model simulated runoff. Observed low flows showed drying trends and drought intensities increased. In the Jucar (Spain), Po (Italy), and Syros (Greece), the intensity increased by 20-25%, whereas the increase in Portugal was about 5% (1963-2001). Uncertainty in trends in drought characteristics is presented, on a pan-European scale and for selected Mediterranean study areas, through model intercomparison and through comparison against observed characteristics. Modeling

  19. An agricultural drought index to incorporate the irrigation process and reservoir operations: A case study in the Tarim River Basin

    Science.gov (United States)

    Li, Zehua; Hao, Zhenchun; Shi, Xiaogang; Déry, Stephen J.; Li, Jieyou; Chen, Sichun; Li, Yongkun

    2016-08-01

    To help the decision making process and reduce climate change impacts, hydrologically-based drought indices have been used to determine drought severity in the Tarim River Basin (TRB) over the past decades. As the major components of the surface water balance, however, the irrigation process and reservoir operations have not been incorporated into drought indices in previous studies. Therefore, efforts are needed to develop a new agricultural drought index, which is based on the Variable Infiltration Capacity (VIC) model coupled with an irrigation scheme and a reservoir module. The new drought index was derived from the simulated soil moisture data from a retrospective VIC simulation from 1961 to 2007 over the irrigated area in the TRB. The physical processes in the coupled VIC model allow the new agricultural drought index to take into account a wide range of hydrologic processes including the irrigation process and reservoir operations. Notably, the irrigation process was found to dominate the surface water balance and drought evolution in the TRB. Furthermore, the drought conditions identified by the new agricultural drought index presented a good agreement with the historical drought events that occurred in 1993-94, 2004, and 2006-07, respectively. Moreover, the spatial distribution of coupled VIC model outputs using the new drought index provided detailed information about where and to what extent droughts occurred.

  20. Groundwater as an emergency source for drought mitigation in the Crocodile River catchment, South Africa

    Directory of Open Access Journals (Sweden)

    F. E. F. Mussá

    2014-03-01

    and environmental damages to the society. In this study, we assess the drought intensity and severity and the groundwater potential to be used as a supplement source of water to mitigate drought impacts in the Crocodile River catchment, a water-stressed sub-catchment of the Incomati River catchment in South Africa. The research methodology consists mainly of three parts. First, the spatial and temporal variation of the meteorological and hydrological drought severity and intensity over the catchment were evaluated. The Standardized Precipitation Index (SPI was used to analyse the meteorological drought and the Standardized Runoff Index (SRI was used for the hydrological drought. Second, the water deficit in the catchment during the drought period was computed using a simple water balance method. Finally, a groundwater model was constructed in order to assess the feasibility of using groundwater as an emergency source for drought impact mitigation. Results show that the meteorological drought severity varies accordingly with the precipitation; the low rainfall areas are more vulnerable to severe meteorological droughts (lower and upper crocodile. Moreover, the most water stressed sub-catchments with high level of water uses but limited storage, such as the Kaap located in the middle catchment and the Lower Crocodile sub-catchments are those which are more vulnerable to severe hydrological droughts. The analysis of the potential groundwater use during droughts showed that a deficit of 97 Mm3 yr−1 could be supplied from groundwater without considerable adverse impacts on the river base flow and groundwater storage. Abstraction simulations for different scenarios of extremely severe droughts reveal that it is possible to use groundwater to cope with the droughts in the catchment. However, local groundwater exploitation in Nelspruit and White River sub-catchment will cause large drawdowns (> 10 m and high base flow reduction (> 20%. This case study shows that

  1. Not all droughts are created equal: translating meteorological drought into woody plant mortality.

    Science.gov (United States)

    Anderegg, Leander D L; Anderegg, William R L; Berry, Joseph A

    2013-07-01

    Widespread drought-induced mortality of woody plants has recently occurred worldwide, is likely to be exacerbated by future climate change and holds large ecological consequences. Yet despite decades of research on plant-water relations, the pathways through which drought causes plant mortality are poorly understood. Recent work on the physiology of tree mortality has begun to reveal how physiological dysfunction induced by water stress leads to plant death; however, we are still far from being able to predict tree mortality using easily observed or modeled meteorological variables. In this review, we contend that, in order to fully understand when and where plants will exceed mortality thresholds when drought occurs, we must understand the entire path by which precipitation deficit is translated into physiological dysfunction and lasting physiological damage. In temperate ecosystems with seasonal climate patterns, precipitation characteristics such as seasonality, timing, form (snow versus rain) and intensity interact with edaphic characteristics to determine when and how much water is actually available to plants as soil moisture. Plant and community characteristics then mediate how quickly water is used and seasonally varying plant physiology determines whether the resulting soil moisture deficit is physiologically damaging. Recent research suggests that drought seasonality and timing matter for how an ecosystem experiences drought. But, mortality studies that bridge the gaps between climatology, hydrology, plant ecology and plant physiology are rare. Drawing upon a broad hydrological and ecological perspective, we highlight key and underappreciated processes that may mediate drought-induced tree mortality and propose steps to better include these components in current research.

  2. Regional validity of the parameters of a distributed runoff-erosion model in the semi-arid region of Brazil

    Institute of Scientific and Technical Information of China (English)

    SRINIVASAN; Vajapeyam; Srirangachar; PAIVA; Fernanda; Maria; de; Lima

    2009-01-01

    The present paper examines the validity of the application of a distributed rainfall-runoff-erosion model on a regional basis in a semi-arid region of Brazil. The model tested is known as WESP (Water Erosion Simulation Program) developed by Lopes (1987). The model simulates the hydrograph and the sediment graph for individual events and thus, the model when properly calibrated can serve as a predictive tool for runoff and soil erosion on an individual or a continuous basis. The possibility of the existence of regionally applicable values for the parameters of the model WESP would be very interesting from the point of view of predictability of runoff and soil erosion from ungauged basins in the region. For this purpose, data collected in several experimental units in the experimental basin of Sumé as well as in the experimental basin of So Joo de Cariri have been used. The model was calibrated and validated in each of the experimental units (consisting of erosion plots and micro-basins) and the average value from all of the units for each of the parameters was considered to be the regional value. With these average values, all the events in all the experimental units were simulated. The results show that the runoff and erosion values simulated with this single parameter set were very good in all the units, being well within the acceptable deviations.

  3. Regional validity of the parameters of a distributed runoff-erosion model in the semi-arid region of Brazil

    Institute of Scientific and Technical Information of China (English)

    SRINIVASAN Vajapeyam Srirangachar; PAIVA Fernanda Maria de Lima

    2009-01-01

    The present paper examines the validity of the application of a distributed rainfall-runoff-erosion model on a regional basis in a semi-arid region of Brazil.The model tested is known as WESP (Water Erosion Simulation Program) developed by Lopes (1987).The model simulates the hydrograph and the sedi-ment graph for individual events and thus, the model when properly calibrated can serve as a predic-tive tool for runoff and soil erosion on an individual or a continuous basis.The possibility of the exis-tence of regionally applicable values for the parameters of the model WESP would be very interesting from the point of view of predictability of runoff and soil erosion from ungauged basins in the region.For this purpose, data collected in several experimental units in the experimental basin of Sume as well as in the experimental basin of Sao Joao de Cariri have been used.The model was calibrated and validated in each of the experimental units (consisting of erosion plots and micro-basins) and the av-erage value from all of the units for each of the parameters was considered to be the regional value.With these average values, all the events in all the experimental units were simulated.The results show that the runoff and erosion values simulated with this single parameter set were very good in all the units, being well within the acceptable deviations.

  4. Drought Risk Assessment based on Natural and Social Factors

    Science.gov (United States)

    Huang, Jing; Wang, Huimin; Han, Dawei

    2015-04-01

    In many parts of the world, drought hazard is becoming more frequent and severe due to climate change and human activities. It is crucial to monitor and assess drought conditions, especially for decision making support in agriculture sector. The vegetation index (VI) decreases, and the land surface temperature (LST) increases when the vegetation is under drought stress. Therefore both of these remotely sensed indices are widely used in drought monitoring and assessment. Temperature-Vegetation Dryness Index (TVDI) is obtained by establishing the feature space of the normalized difference vegetation index (NDVI) and LST, which reflects agriculture dry situation by inverting soil moisture. However, these indices only concern the natural hazard-causing factors. Our society is a complex large-scale system with various natural and social elements. The drought risk is the joint consequence of hazard-causing factors and hazard-affected bodies. For example, as the population increases, the exposure of the hazard-affected bodies also tends to increase. The high GDP enhances the response ability of government, and the irrigation and water conservancy reduces the vulnerability. Such characteristics of hazard-affected bodies should be coupled with natural factors. In this study, the 16-day moderate-resolution imaging spectroradiometer (MODIS) NDVI and LST data are combined to establish NDVI-Ts space according to different land use types in Yunnan Province, China. And then, TVDIs are calculated through dry and wet edges modeled as a linear fit to data for each land cover type. Next, the efforts are turned to establish an integrated drought assessment index of social factors and TVDI through ascertaining attribute weight based on rough sets theory. Thus, the new CDI (comprehensive drought index) recorded during spring of 2010 and the spatial variations in drought are analyzed and compared with TVDI dataset. Moreover, actual drought risk situation in the study area is given to

  5. U.S. agriculture in a modern Dust Bowl drought

    Science.gov (United States)

    Glotter, M.; Chryssanthacopoulos, J.; Moyer, E. J.; Elliott, J. W.

    2015-12-01

    Drought-induced agricultural loss is one of the leading weather-related harms to the U.S. economy, but little is known about the effects of extreme droughts or of consecutive multi-year drought events on agriculture. Three droughts in the early 1930s make the Dust Bowl era the driest and hottest for agriculture in modern U.S. history and a useful analog to study extreme weather and its impact on human society. Improvements in technology and farm management over the last eight decades have dramatically increased average crop yields in the U.S., but the elimination of most non-climatic crop stresses means rainfed yields are now more tightly linked to climate. To understand how a 1930s-type drought would affect agriculture in the modern U.S., we drive empirical and biophysical process-based crop models with 1930s weather -- with and without increases in mean temperature -- to estimate effects of successive droughts on current and near-future U.S. maize, soy and wheat production. Our results suggest that Dust-Bowl-type droughts today would have unprecedented consequences for agricultural productivity, with single-year losses up to ~50% larger than the central U.S. drought of 2012, one of the most severe for modern agriculture. Sensitivity tests imply that damages at these extremes are highly sensitive to temperature. If extreme drought conditions are even modestly warmer (1-4 oC), single-year losses jump to more than twice the 2012 drought. Assuming that repeated crop failure over a relatively short period is likely to induce changes to land-use and management, we find that a future Dust-Bowl-like drought, especially under higher temperature scenarios, could lead to significant long-term consequences for U.S. agriculture. Changes in climate may increase the severity and frequency of future droughts, so understanding the complex interactions of weather extremes and a changing agricultural system is critical to effective preparation and response if and when the next Dust

  6. Recent La Plata basin drought conditions observed by satellite gravimetry

    CERN Document Server

    Chen, J L; Tapley, B D; Longuevergne, L; Yang, Z L; Scanlon, B R; 10.1029/2010JD014689

    2010-01-01

    The Gravity Recovery and Climate Experiment (GRACE) provides quantitative measures of terrestrial water storage (TWS) change. GRACE data show a significant decrease in TWS in the lower (southern) La Plata river basin of South America over the period 2002-2009, consistent with recognized drought conditions in the region. GRACE data reveal a detailed picture of temporal and spatial evolution of this severe drought event, which suggests that the drought began in lower La Plata in around austral spring 2008 and then spread to the entire La Plata basin and peaked in austral fall 2009. During the peak, GRACE data show an average TWS deficit of ~12 cm (equivalent water layer thickness) below the 7 year mean, in a broad region in lower La Plata. GRACE measurements are consistent with accumulated precipitation data from satellite remote sensing and with vegetation index changes derived from Terra satellite observations. The Global Land Data Assimilation System model captures the drought event but underestimates its in...

  7. use of LOGARITHMIC FUNCTION FOR DROUGHT SEVERITY ASSESSMENT

    Directory of Open Access Journals (Sweden)

    I.C. STÂNGĂ

    2011-03-01

    Full Text Available Use of logarithmic function for drought severity assessment. Due to the multiplicative and cumulative effect of various risk events, the use of logarithmic function can provide satisfactory results in the analysis of risks. Based on the monthly values of climatic parameters from fourteen stations in the eastern part of Romania (1961-2006, the author uses the logarithmic function to evaluate and interpret the severity of droughts. With this function, deficient rainfall periods are diagnosed and classified according to three levels (moderate, high and extreme droughts. On these bases, the mathematical modeling allows to assess and evaluate the susceptibility to drought phenomena and the degree of continentalism in the eastern part of Romania.

  8. Consumer contribution to food contamination in Brazil: modelling the food safety risk in the home

    Directory of Open Access Journals (Sweden)

    Sergio Paulo Olinto da Motta

    2014-06-01

    Full Text Available Foodborne diseases are among the most widespread public health issues, killing about 2.2 million people annually, and costing hundreds of billions of US dollars for governments, companies, families and consumers (WHO, 2007. In Brazil, foodborne diseases acquired in the home account for 55% of notified outbreaks (BRASIL, 2012. Several studies have investigated aspects of consumer behaviour concerning food poisoning, mapping practices in the home, but it remains a challenge to obtain a full picture of the consumer contribution to food contamination (REDMOND and GRIFFITH, 2003. This study aimed to assess the risks of food contamination in the home. A questionnaire containing 140 questions concerning food safety knowledge, handling practices, personal hygiene and basic health care, covering the stages when the food is under the control of the consumer, was developed and used to gather data for analysis. Appropriate scores were attributed to the questions (consequences to food safety and answers (likelihood of food contamination. A risk estimate algorithm and an appropriate risk ranking scale were used to assess the results. From August 2011 to March 2012, survey questionnaires were collected from 2,775 consumers in Brazil across 19 out of 27 state capitals. The study found risky practices with the potential to lead to food poisoning occurrences in the domestic environment in the following handling steps: food transportation, food preparation, cooking and the handling of leftovers. The personal hygiene, age, formal education, family income and basic health care habits represented the factors most related to the risky practices of consumers, which could orientate food safety educational campaigns for the Brazilian population.

  9. Comparison of empirical and data driven hydrometeorological hazard models on coastal cities of São Paulo, Brazil

    Science.gov (United States)

    Koga-Vicente, A.; Friedel, M. J.

    2010-12-01

    Every year thousands of people are affected by floods and landslide hazards caused by rainstorms. The problem is more serious in tropical developing countries because of the susceptibility as a result of the high amount of available energy to form storms, and the high vulnerability due to poor economic and social conditions. Predictive models of hazards are important tools to manage this kind of risk. In this study, a comparison of two different modeling approaches was made for predicting hydrometeorological hazards in 12 cities on the coast of São Paulo, Brazil, from 1994 to 2003. In the first approach, an empirical multiple linear regression (MLR) model was developed and used; the second approach used a type of unsupervised nonlinear artificial neural network called a self-organized map (SOM). By using twenty three independent variables of susceptibility (precipitation, soil type, slope, elevation, and regional atmospheric system scale) and vulnerability (distribution and total population, income and educational characteristics, poverty intensity, human development index), binary hazard responses were obtained. Model performance by cross-validation indicated that the respective MLR and SOM model accuracy was about 67% and 80%. Prediction accuracy can be improved by the addition of information, but the SOM approach is preferred because of sparse data and highly nonlinear relations among the independent variables.

  10. Fitting mathematical models to lactation curves from holstein cows in the southwestern region of the state of Parana, Brazil

    Directory of Open Access Journals (Sweden)

    Abílio G.T. Ferreira

    2015-03-01

    Full Text Available The objective of this study was to evaluate four mathematical models with regards to their fit to lactation curves of Holstein cows from herds raised in the southwestern region of the state of Parana, Brazil. Initially, 42,281 milk production records from 2005 to 2011 were obtained from "Associação Paranaense de Criadores de Bovinos da Raça Holandesa (APCBRH". Data lacking dates of drying and total milk production at 305 days of lactation were excluded, resulting in a remaining 15,142 records corresponding to 2,441 Holstein cows. Data were sorted according to the parity order (ranging from one to six, and within each parity order the animals were divided into quartiles (Q25%, Q50%, Q75% and Q100% corresponding to 305-day lactation yield. Within each parity order, for each quartile, four mathematical models were adjusted, two of which were predominantly empirical (Brody and Wood whereas the other two presented more mechanistic characteristics (models Dijkstra and Pollott. The quality of fit was evaluated by the corrected Akaike information criterion. The Wood model showed the best fit in almost all evaluated situations and, therefore, may be considered as the most suitable model to describe, at least empirically, the lactation curves of Holstein cows raised in Southwestern Parana.

  11. Robust assessment of spatial non-stationarity in model associations related to pediatric mortality due to diarrheal disease in Brazil.

    Science.gov (United States)

    Leyk, Stefan; Norlund, Petra U; Nuckols, John R

    2012-06-01

    Approximately 1.5 million people, mostly children, die annually due to disease attributed to diarrhea reflecting urgent needs for improved understanding of associations between the disease and potential risk factors. Numerous epidemiological studies found spatially varying (non-stationary) disease associations attributable to changing geographic or demographic context. Spatial non-stationarity implies that average relationships from statistical models fitted to the whole study area might be inappropriate since they do not reflect local conditions. Spatial modeling techniques such as geographically weighted regression (GWR) have limitations in providing statistically robust analysis of spatial non-stationarity. Thus, there is a need for development or expansion of modeling techniques to address this issue. Using data for pediatric diarrheal mortality in Brazil in 2000, and different risk factors, we develop an analytical framework to determine regions of similar (stationary) local associations by combining GWR and max-p regionalization. We fit statistical models to these regions, and compare goodness-of-fit and regionally varying coefficients to the national-scale model measures. The proposed framework allows us to examine (a) impact of non-stationarity for regions of different geographic extent with acceptable statistical power, (b) the explanatory power of each risk factor in each region, and (c) if these regions reflect changing data quality or truly existing variations in putative associations.

  12. Fitting mathematical models to lactation curves from Holstein cows in the southwestern region of the state of Parana, Brazil.

    Science.gov (United States)

    Ferreira, Abílio G T; Henrique, Douglas S; Vieira, Ricardo A M; Maeda, Emilyn M; Valotto, Altair A

    2015-03-01

    The objective of this study was to evaluate four mathematical models with regards to their fit to lactation curves of Holstein cows from herds raised in the southwestern region of the state of Parana, Brazil. Initially, 42,281 milk production records from 2005 to 2011 were obtained from "Associação Paranaense de Criadores de Bovinos da Raça Holandesa (APCBRH)". Data lacking dates of drying and total milk production at 305 days of lactation were excluded, resulting in a remaining 15,142 records corresponding to 2,441 Holstein cows. Data were sorted according to the parity order (ranging from one to six), and within each parity order the animals were divided into quartiles (Q25%, Q50%, Q75% and Q100%) corresponding to 305-day lactation yield. Within each parity order, for each quartile, four mathematical models were adjusted, two of which were predominantly empirical (Brody and Wood) whereas the other two presented more mechanistic characteristics (models Dijkstra and Pollott). The quality of fit was evaluated by the corrected Akaike information criterion. The Wood model showed the best fit in almost all evaluated situations and, therefore, may be considered as the most suitable model to describe, at least empirically, the lactation curves of Holstein cows raised in Southwestern Parana.

  13. Politics and drought planning: Friends or foes?

    International Nuclear Information System (INIS)

    Nothing frustrates the average drought planner more than politics. Yet, droughts cannot be prepared for realistically without reliable political partners, smoothly cooperating government agencies, and strong public support. This paper suggests six rules for linking technical drought planning processes to the political processes and institutions that can implement drought plans

  14. 33 CFR 203.62 - Drought assistance.

    Science.gov (United States)

    2010-07-01

    ... 33 Navigation and Navigable Waters 3 2010-07-01 2010-07-01 false Drought assistance. 203.62... Supplies: Contaminated Water Sources and Drought Assistance § 203.62 Drought assistance. (a) Authority. The... political subdivisions, within areas determined to be drought-distressed. (b) General policy. (1) It is...

  15. Root Niche Separation as Strategy of Avoidance of Seasonal Drought Stress in a Mature Amazonian Forest (Invited)

    Science.gov (United States)

    Ivanov, V. Y.; Hutyra, L.; Wofsy, S. C.; Munger, J. W.; Saleska, S. R.; De Oliveira, R., Jr.; Camargo, P. B.; Fatichi, S.

    2013-12-01

    Large areas of Amazonian evergreen forests experience seasonal droughts extending for three or more months, and show maximum rates of photosynthesis and evapotranspiration during dry intervals. This apparent resilience is belied by disproportionate mortality of the large trees in manipulations that reduce wet season rainfall, occurring after 2-3 years of treatment. The goal of this study is to characterize the mechanisms that produce these contrasting ecosystem responses. A mechanistic vegetation-hydrology model is developed to test the roles of deep roots and the possibility of 'root niche separation,' in which roots of overstory trees extend to depth, where during the dry season they use water stored from wet season precipitation, while roots of understory trees are concentrated in shallow layers that access dry season precipitation directly. Observational data on canopy phenology, energy fluxes, soil moisture, and soil and root structure from the Tapajos National Forest, Brazil, provided comprehensive observational constraints on the model. Results strongly suggest that deep roots with root niche separation adaptations explain both the observed resilience during seasonal drought and the vulnerability of canopy-dominant trees to extended deficits of wet season rainfall. These mechanisms appear to provide an adaptive strategy that enhances productivity of the largest trees in the face of their disproportionate heat loads and water demand in the dry season. A sensitivity analysis exploring how wet season rainfall affects the stability of the rainforest system is presented.

  16. Extreme drought events in Germany during the last 60 yrs

    Science.gov (United States)

    Samaniego, L. E.; Kumar, R.; Zink, M.

    2011-12-01

    Droughts are among the most costly natural disasters because they heavily impact on the economy of a region as well as on its social and cultural activities. Droughts do not only occur in arid or semiarid regions but also in humid ones. The year 2007, for example, was the sunniest, hottest and driest in Germany in the last two centuries. In this case, it was too dry too early. As a result, the harvest was cut by half leading to enormous losses in the primary sector. Consumer prices of some agricultural products went up 26 percent. The purpose of this study is to identify the major agricultural and hydrological droughts in Germany since 1950 based on their severity, duration and areal extend. To achieve this goal, a 60-yr retrospective hydrological simulation of the land surface water budget over Germany was carried out with the process-based distributed hydrological model mHM. The model was forced with grided daily precipitation and temperature data at 4x4 km, and the model simulations were carried out at same spatial resolutions. Point measurement data from more than 5600 raingauges and about 1120 meteorological stations (DWD) were interpolated with EDK. Land cover change was also considered during this period. Drought indices were derived as monthly quantiles of the simulated fluxes which include root zone soil moisture and total runoff. A Gaussian kernel smoother was used to estimate these quantiles at each grid cell. A spatio-temporal cluster algorithm was used to consolidate all significant drought events. Main statistics such as magnitude, areal extend, duration, and severity were estimated only on those selected clusters. The mHM model was calibrated in major river basins giving Nash-Sutcliffe efficiencies for daily discharge simulations greater than 0.8 in the evaluation period. Plausibility tests between the simulated mHM soil moisture and land surface temperature from MODIS and regional climate model reanalysis data compared well. Results indicated that

  17. Reaction norms models in the adjusted weight at 550 days of age for Polled Nellore cattle in Northeast Brazil

    Directory of Open Access Journals (Sweden)

    Diego Pagung Ambrosini

    2014-07-01

    Full Text Available The objective of this study was to evaluate the genotype-environment interaction (GEI in the body weight adjusted to 550 days of age (W550 of Polled Nellore cattle raised in Northeastern Brazil using reaction norms (RN models. Hierarchical RN models included fixed effects for age of cow (linear and quadratic and random effects for contemporary groups (CG and additive genetic RN level and slope. Four RN hierarchical models (RNHM were used. The RNHM2S uses the solutions of contemporary groups estimated by the standard animal model (AM and considers them as environmental level for predicting the reaction norms and the RNHM1S, which jointly estimate these two sets of unknowns. Two versions were considered for both models, one with a homogeneous (Hm and another with a heterogeneous (He residual variance. The one-step homogeneous residual variance model (RNHM1SHm offered better adjustment to the data when compared with other models. For the RNHM1SHm model, estimates of additive genetic variance and heritability increased with environment improvement (260.75±75.80 kg2 to 4298.39±356.56 kg2 and 0.22±0.05 to 0.82±0.01, for low- and high-performance environments, respectively. High correlation (0.97±0.01 between the intercept and the slope of RN shows that animals with higher genetic values respond better to environment improvement. In the evaluation of breeding sires with higher genetic values in the various environments using Spearman's correlation, values between 0 and 0.98 were observed, pointing to high reclassification, especially among genetic values obtained by the animal model in comparison with those obtained via RNHM1SHm. The existence of GEI is confirmed, and so is the need for specific evaluations for low, medium and high level production environments.

  18. Assessing various drought indicators in representing summer drought in boreal forests in Finland

    Science.gov (United States)

    Gao, Y.; Markkanen, T.; Thum, T.; Aurela, M.; Lohila, A.; Mammarella, I.; Kämäräinen, M.; Hagemann, S.; Aalto, T.

    2016-01-01

    Droughts can have an impact on forest functioning and production, and even lead to tree mortality. However, drought is an elusive phenomenon that is difficult to quantify and define universally. In this study, we assessed the performance of a set of indicators that have been used to describe drought conditions in the summer months (June, July, August) over a 30-year period (1981-2010) in Finland. Those indicators include the Standardized Precipitation Index (SPI), the Standardized Precipitation-Evapotranspiration Index (SPEI), the Soil Moisture Index (SMI), and the Soil Moisture Anomaly (SMA). Herein, regional soil moisture was produced by the land surface model JSBACH of the Max Planck Institute for Meteorology Earth System Model (MPI-ESM). Results show that the buffering effect of soil moisture and the associated soil moisture memory can impact on the onset and duration of drought as indicated by the SMI and SMA, while the SPI and SPEI are directly controlled by meteorological conditions. In particular, we investigated whether the SMI, SMA and SPEI are able to indicate the Extreme Drought affecting Forest health (EDF), which we defined according to the extreme drought that caused severe forest damages in Finland in 2006. The EDF thresholds for the aforementioned indicators are suggested, based on the reported statistics of forest damages in Finland in 2006. SMI was found to be the best indicator in capturing the spatial extent of forest damage induced by the extreme drought in 2006. In addition, through the application of the EDF thresholds over the summer months of the 30-year study period, the SPEI and SMA tended to show more frequent EDF events and a higher fraction of influenced area than SMI. This is because the SPEI and SMA are standardized indicators that show the degree of anomalies from statistical means over the aggregation period of climate conditions and soil moisture, respectively. However, in boreal forests in Finland, the high initial soil moisture

  19. Possible Future Climate Change Impacts on the Hydrological Drought Events in the Weihe River Basin, China

    OpenAIRE

    Fei Yuan; Mingwei Ma; Liliang Ren; Hongren Shen; Yue Li; Shanhu Jiang; Xiaoli Yang; Chongxu Zhao; Hao Kong

    2016-01-01

    Quantitative evaluation of future climate change impacts on hydrological drought characteristics is one of important measures for implementing sustainable water resources management and effective disaster mitigation in drought-prone regions under the changing environment. In this study, a modeling system for projecting the potential future climate change impacts on hydrological droughts in the Weihe River basin (WRB) in North China is presented. This system consists of a large-scale hydrologi...

  20. Variability of runoff-based drought conditions in the conterminous United States

    Science.gov (United States)

    McCabe, Gregory; Wolock, David M.; Austin, Samuel H.

    2016-01-01

    In this study, a monthly water-balance model is used to simulate monthly runoff for 2109 hydrologic units (HUs) in the conterminous United States (CONUS) for water-years 1901 through 2014. The monthly runoff time series for each HU were smoothed with a 3-month moving average, and then the 3-month moving-average runoff values were converted to percentiles. For each HU, a drought was considered to occur when the HU runoff percentile dropped to the 20th percentile or lower. A drought was considered to end when the HU runoff percentile exceeded the 20th percentile. After identifying drought events for each HU, the frequency and length of drought events were examined. Results indicated that (1) the longest mean drought lengths occur in the eastern CONUS and parts of the Rocky Mountain region and the northwestern CONUS, (2) the frequency of drought is highest in the southwestern and central CONUS, and lowest in the eastern CONUS, the Rocky Mountain region, and the northwestern CONUS, (3) droughts have occurred during all months of the year and there does not appear to be a seasonal pattern to drought occurrence, (4) the variability of precipitation appears to have been the principal climatic factor determining drought, and (5) for most of the CONUS, drought frequency appears to have decreased during the 1901 through 2014 period.

  1. Monitoring southwest drought of China using HJ-1A/B and Landsat remote sensing data

    Science.gov (United States)

    Huang, He; Zhou, Hongjian; Wang, Ping; Wu, Wei; Yang, Siquan

    2012-10-01

    Drought is one major nature disaster in the world. The affected population and agriculture loss caused by drought are the largest in all natural disasters. Drought has the characteristics of wide affected areas, long duration and periodic strong feature. Remote sensing has the advantages of large coverage, frequent observation, repeatable observation, reliable information source and low cost. These advantages make remote sensing a vital contributor for drought disaster monitoring and forecasting. So, remote sensing data have been widely used and delivered significant benefits in drought prevention and reduction in China. Three drought monitor models including Vegetation Condition Index (VCI), Temperature Condition Index (TCI) and Temperature Vegetation Dryness Index (TVDI) had been used to monitor southwest drought occurred in China from 2009 to 2011 based on the small satellite constellation for environment and disaster monitoring and forecasting A/B satellites (HJ-1AB) and Landsat remote sensing data. The results shown that five regions including Sichuan province, Chongqing, Guizhou province, Yunnan province, Guangxi province in southwest of China had suffered different degrees agricultural drought disaster in 2010 and 2011. The comprehensive agricultural disaster situation of five affected areas in 2010 was more serious than drought events occurred in 2011. The many regions in Guizhou province were hardest-hit areas cased by the two consecutive year drought events in southwest China.

  2. Drought Legacy and the Impacts on the Amazon Forest Carbon Exchange

    Science.gov (United States)

    Saatchi, S. S.

    2015-12-01

    Sassan Saatchi1,2, Yifan Yu1, Xiang Xu2, Luiz Aragao3, Liana Anderson31Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109, USA2Institute of Environment and Sustainability, University of California, Los Angeles, CA 90045. USA3 Remote Sensing Division, National Institute for Space Research, São José dos Campos, Brazil, 12227-010, BrazilRecent Amazonian droughts have drawn attention to the vulnerability of tropical forests to climate perturbations. Ground and satellite observations of 2005 and 2010 mega-droughts have shown an increase in fire occurrence and tree mortality during the period of drought. Here, we use a combination of satellite observations over a period of about 15 years to examine the legacy of the droughts in terms of impacts on the ecological structure and function of the forests in years following the droughts and the subsequent carbon exchange. Using data from microwave satellite sensors of rainfall, canopy backscatter (2000-2014) and GRACE and GOSAT, we show that the 2005 drought has a legacy of 2-5 years in western Amazonia, by increasing the disturbance in canopy trees and impacting the gross primary production of the forest significantly. Amazonian forests, particularly in the southern region were again impacted by the 2010 mega-drought, causing a legacy of 2-4 years with potential decrease in GPP and productivity observed by GOSAT fluorescence. The persistent of low canopy water content observed by a joint QSCAT and OceanSAT observations were linked to a delay in recharging of the hydrological system observed by GRACE over a period of 2-5 years. The results suggest that Amazonian forests with distinct dry seasons in southern and western regions of the basin are potentially more vulnerable to droughts compared to regions with less seasonality. The long recovery time from the 2005 and 2010 droughts suggests that the occurence of droughts in Amazonia at 5-10 year frequency may lead to long-term alteration of the

  3. Modeling field-scale vertical movement of zinc and copper in a pig slurry-amended soil in Brazil.

    Science.gov (United States)

    Mallmann, Fábio Joel Kochem; dos Santos, Danilo Rheinheimer; Ceretta, Carlos Alberto; Cella, Cesar; Simůnek, Jirka; van Oort, Folkert

    2012-12-01

    Organic amendments often represent a source of trace metals (TMs) in soils, which may partly leach into the groundwater. The objectives of this study were (1) to validate Hydrus-2D for modeling the transport of Zn and Cu in an Alfisol amended with pig slurry (PS) by comparing numerical simulations and experimental field data, and (2) to model the next 50 years of TM movements under scenarios of suspended or continued PS amendments. First, between 2000 and 2008, we collected detailed Zn and Cu data from a soil profile in Santa Maria, Brazil. Two hypotheses about Zn and Cu reactivity with the solid phase were tested, considering physical, hydraulic, and chemical characteristics of six soil layers. Using a two-site sorption model with a sorption kinetic rate adjusted based on laboratory EDTA extractions, Hydrus simulations of the vertical TM transport were found to satisfactorily describe the soil Zn and Cu concentration profiles. Second, the long-term fate of Zn and Cu in the soil was assessed using the validated parameterized model. Numerical simulations showed that Zn and Cu did not present risks for groundwater pollution. However, future Cu accumulation in the surface soil layer would exceed the Brazilian threshold for agricultural soils.

  4. Improving Regional Dynamic Downscaling with Multiple Linear Regression Model Using Components Principal Analysis: Precipitation over Amazon and Northeast Brazil

    Directory of Open Access Journals (Sweden)

    Aline Gomes da Silva

    2014-01-01

    Full Text Available In the current context of climate change discussions, predictions of future scenarios of weather and climate are crucial for the generation of information of interest to the global community. Due to the atmosphere being a chaotic system, errors in predictions of future scenarios are systematically observed. Therefore, numerous techniques have been tested in order to generate more reliable predictions, and two techniques have excelled in science: dynamic downscaling, through regional models, and ensemble prediction, combining different outputs of climate models through the arithmetic average, in other words, a postprocessing of the output data species. Thus, this paper proposes a method of postprocessing outputs of regional climate models. This method consists in using the statistical tool multiple linear regression by principal components for combining different simulations obtained by dynamic downscaling with the regional climate model (RegCM4. Tests for the Amazon and Northeast region of Brazil (South America showed that the method provided a more realistic prediction in terms of average daily rainfall for the analyzed period prescribed, after comparing with the prediction made by set through the arithmetic averages of the simulations. This method photographed the extreme events (outlier that the prediction by averaging failed. Data from the Tropical Rainfall Measuring Mission (TRMM were used to evaluate the method.

  5. Mathematical model for timber decay in contact with the ground adjusted for the state of São Paulo, Brazil

    Directory of Open Access Journals (Sweden)

    Roberto Ramos de Freitas

    2010-06-01

    Full Text Available At this moment, the environmental sustainability has been incorporated to all branches of activity more and more; timber seems to be the best alternative in civil construction. Nevertheless, for a correct and better usage of timber as a structural material, it is necessary to have a higher degree of knowledge not only of the structural mechanical behavior, but also about its durability and service life. With help from mathematical models the service life of the timber structures can be foreseen, by obtaining the "Climate Indices", that show comparatively among the studied regions, which ones have a higher or lesser propensity of being attacked by fungi. In this paper, utilizing climatologic data from several cities of the State of São Paulo - Brazil was determined through numerical analysis and statistics, the simplification of one aggressive model to timber in contact with the ground, being this model adjusted to the State of São Paulo. The simplified model of timber degradation can be used to quantity the effect of the environment in the process of decay for the regional climatic conditions.

  6. DroughtView: Satellite Based Drought Monitoring and Assessment

    Science.gov (United States)

    Hartfield, K. A.; Van Leeuwen, W. J. D.; Crimmins, M.; Marsh, S. E.; Torrey, Y.; Rahr, M.; Orr, B. J.

    2014-12-01

    Drought is an ever growing concern within the United States and Mexico. Extended periods of below-average precipitation can adversely affect agricultural production and ecosystems, impact local water resources and create conditions prime for wildfire. DroughtView (www.droughtview.arizona.edu) is a new on-line resource for scientists, natural resource managers, and the public that brings a new perspective to remote-sensing based drought impact assessment that is not currently available. DroughtView allows users to monitor the impact of drought on vegetation cover for the entire continental United States and the northern regions of Mexico. As a spatially and temporally dynamic geospatial decision support tool, DroughtView is an excellent educational introduction to the relationship between remotely sensed vegetation condition and drought. The system serves up Normalized Difference Vegetation Index (NDVI) and Enhanced Vegetation Index (EVI) data generated from 250 meter 16-day composite Moderate-resolution Imaging Spectroradiometer (MODIS) imagery from 2000 to the present. Calculation of difference from average, previous period and previous year greenness products provide the user with a proxy for drought conditions and