Sample records for brazilian semi-arid region

  1. Using GNSS observations to investigate variations of Pluviometry in the Semi-Arid Brazilian region (United States)

    Silva, Mario; Fernandes, Rui; Nascimento, Aderson; Petta, Reinaldo; Matschullat, Jörg; Monico, João; Bos, Machiel; Sá, Andre; Barbosa, Marx


    The Semi-Arid Brazilian region is the most densely populated, semi-arid region in the world. It is located in the Northeastern part of Brazil and corresponds to approximately 982,563 square kilometers (about 11% of the total Brazilian territory). The temperatures remain nearly uniform throughout the year and are typically tropical, often extremely hot with little interannual variability, exert a strong effect on the potential evapotranspiration, which in turn determine the annual water deficit leading to extensive droughts in some years. The annual rainfall averages between 500 and 800 millimeters and have great climatic variability and an irregular distribution in space and time. Most of the year the region is strongly influenced by the inter-tropical convergence zone which remains in the northern hemisphere near the equator most of the year due to the cold waters of the Atlantic Ocean. The GNSS technique has been established as a valid tool to sense the amount of PWV in the atmosphere. The direct estimated product is the ZTD (Zenith Troposphere Delay) that can be transformed to PWV by knowing the Pressure and Temperature at the station position. However, such values are not always collected together with the GNSS observations, which can force us to limit the analysis to the ZTD directly. In this work we have used data of the existing continuous GNSS (Global Navigation Satellite Systems) stations in the Semi-Arid Brazil to investigate the variability of precipitable water vapor (PWV) in the region. We firstly analysis the accuracy of using global models of pressure and temperature fields to calculate the PWV at the GNSS station locations in the Northeast of Brazil. To do such, we have estimated and compared values of PWV using both global models and local measurements at Natal city, Brazil. The differences provide us a reliable estimate of the error associated with the use of global models to compute the PWV from ZTD measurements for Northeastern Brazil. Secondly

  2. Leaf anatomy of six species of Heliotropiaceae Schrad. from the Brazilian semi-arid region

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    Elisabeth Tölke


    Full Text Available The family Heliotropiaceae has more than 450 species, mainly distributed in the tropics and subtropics. In Brazil, it is represented by the genera Euploca Nutt., Heliotropium L., Myriopus Small and Tournefortia L. The aim of this study was to describe the leaf anatomy of six species of Heliotropiaceae recorded in the semi-arid region of Brazil: E. polyphylla (Lehm. J.I.M. Melo & Semir, E. procumbens (Mill. Diane & Hilger, H. angiospermum Murray, H. curassavicum L., M. rubicundus (Salzm. ex DC. Luebert and M. salzmannii (DC. Diane & Hilger. Besides contributing to the knowledge of the anatomy of the representatives of the family in the Caatinga (Brazilian savannah, we also sought to determine and highlight the anatomical features adaptive to the region and to identify features with potential diagnostic value. Leaf structures were analyzed by light microscopy and scanning electron microscopy. Additional tests were also carried out to detect starch and total lipids. The morphological variation and the distribution of trichomes were the most relevant features for species diagnosis. The distribution of stomata in M. salzmannii and H. angiospermum differed from that described in other papers, which demonstrates the anatomical plasticity of these species. This is the first report describing the leaf blade of M. rubicundus.

  3. Leaf anatomy of six species of Heliotropiaceae Schrad. from the Brazilian semi-arid region

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    Elisabeth Emília Augusta Dantas Tölke


    Full Text Available The family Heliotropiaceae has more than 450 species, mainly distributed in the tropics and subtropics. In Brazil, it is represented by the genera Euploca Nutt., Heliotropium L., Myriopus Small and Tournefortia L. The aim of this study was to describe the leaf anatomy of six species of Heliotropiaceae recorded in the semi-arid region of Brazil: E. polyphylla (Lehm. J.I.M. Melo & Semir, E. procumbens (Mill. Diane & Hilger, H. angiospermum Murray, H. curassavicum L., M. rubicundus (Salzm. ex DC. Luebert and M. salzmannii (DC. Diane & Hilger. Besides contributing to the knowledge of the anatomy of the representatives of the family in the Caatinga (Brazilian savannah, we also sought to determine and highlight the anatomical features adaptive to the region and to identify features with potential diagnostic value. Leaf structures were analyzed by light microscopy and scanning electron microscopy. Additional tests were also carried out to detect starch and total lipids. The morphological variation and the distribution of trichomes were the most relevant features for species diagnosis. The distribution of stomata in M. salzmannii and H. angiospermum differed from that described in other papers, which demonstrates the anatomical plasticity of these species. This is the first report describing the leaf blade of M. rubicundus.


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    Juarez Benigno Paes


    Full Text Available The hide tanners of Brazil Northeast region have in Anadenanthera colubrina (Vell. Brenan var. cebil (Gris. Alts. their only source of tannins. As the activity of exploration is extractiviste without the concern of recovery of explored trees and the absence of other tannin sources, exposes the specie to exhaustion and the tanners and extractivistes family to go bankruptcy. Thus, this work aimed to evaluate the tanin potential of Prosopis juliflora, Anadenanthera colubrina var. cebil, Anacardium occidentale, Mimosa tenuiflora, Mimosa arenosa and Croton sonderianus. These species, Anacardium occidentale, Mimosa arenosa and Mimosa temuiflora showed, respectively, 19.83%, 18.11% and 17.74% of tannins. The Anadenanthera colubrina showed 11.89% and was inferior them mentioned species. The Prosopis juliflora and Croton sonderianus showed 3.02% and 6.62%, respectively. The abundance of Mimosa arenosa and Mimosa tenuiflora in the Brazilian Semi-arid proposes them as potential of tannin production. However, there is need of researches to verify their technical viability for skins, as well as for other uses for tannins.

  5. Loxosceles niedeguidonae (Araneae, Sicariidae a new species of brown spider from Brazilian semi-arid region

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    Rute Gonçclves-de-Andrade


    Full Text Available A new species of recluse spider, Loxosceles niedeguidonae sp. n., is described from the Parque Nacional Serra da Capivara, State of Piauí, Brazil. This is the first endemic species described from Brazilian semi-arid environment. The species is included in gaucho group of Gertsch (1967 due to its spermathecal shape and is considered close to L. chapadensis Bertani, Fukushima & Nagahama, 2010 by the unusual long male palpal tibia, a character not common for species of this group. An updated key for Loxosceles species of gaucho group is presented.

  6. Loxosceles niedeguidonae (Araneae, Sicariidae) a new species of brown spider from Brazilian semi-arid region (United States)

    Gonçalves-de-Andrade, Rute Maria; Bertani, Rogério; Nagahama, Roberto Hiroaki; Barbosa, Maria Fatima Ribeiro


    Abstract A new species of recluse spider, Loxosceles niedeguidonae sp. n., is described from the Parque Nacional Serra da Capivara, State of Piauí, Brazil. This is the first endemic species described from Brazilian semi-arid environment. The species is included in gaucho group of Gertsch (1967) due to its spermathecal shape and is considered close to Loxosceles chapadensis Bertani, Fukushima & Nagahama, 2010 by the unusual long male palpal tibia, a character not common for species of this group. An updated key for Loxosceles species of gaucho group is presented. PMID:22451789

  7. Development and water requirements of cowpea under climate change conditions in the Brazilian semi-arid region

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    Edmilson G. Cavalcante Junior

    Full Text Available ABSTRACT This study aimed to determine the impacts that climate change may cause on the development and evapotranspiration of cowpea, in semi-arid climate region of Northeast Brazil. The study was conducted in the municipalities of Apodi, Ipanguaçu and Mossoró, in the state of Rio Grande do Norte. In order to evaluate the influence of climate change on crop water consumption, changes in air temperature and relative humidity were simulated using the PRECIS climate model. Two scenarios of emissions were evaluated based on the report of the Intergovernmental Panel on Climate Change: a pessimistic named A2 and an optimistic B2. The duration of the crop cycle showed an average reduction of 14 and 23 days for the optimistic and pessimistic scenarios, respectively. Temperatures will be well above the limit tolerated by crop, which could have a negative impact on its development and yield. There will be a decrease in total evapotranspiration of 4.8%, considering the optimistic scenario, and 8.7% in the pessimistic scenario.

  8. Agroecology, Public Policies and Labor-Driven Intensification: Alternative Development Trajectories in the Brazilian Semi-Arid Region

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    Paulo F. Petersen


    Full Text Available The institutional recognition obtained by family farming in Brazil over recent decades has translated into the launching of a broad and diverse set of public policies specifically aimed towards this sociopolitical category. However, the design of these policies was heavily influenced by the productivist bias derived from the agricultural modernization paradigm, making the sector increasingly dependent on input and capital markets. In this same movement of institutional evolution, policies consistent with the agroecological approach created new margins for maneuvering for development trajectories founded on the use of local resources self-controlled by rural families and communities. Taking as a reference the recent trajectory of rural development in Brazil’s semi-arid region, the article analyses the role of the agroecological perspective in the strategic combination between territorially endogenous rural resources and public resources redistributed by the State. Based on the analysis of the economy of agroecosystems linked to two sociotechnical networks structured by contrasting logics of productive intensification, the study demonstrates agroecology’s potential as a scientific-technological approach for the combined attainment of various Sustainable Development Goals, starting with the economic and political emancipation of the socially most vulnerable portions of the rural population.

  9. optimization of water resources allocation in semi-arid region

    African Journals Online (AJOL)

    Eng Obi Ibeje

    Semi-arid regions are characterized by long, dry seasons and short mild wet seasons. They face periods of water shortages due to high demand and inconsistent supply. Water allocation is often the primary tool of water managers in semi- arid regions (Haten–Moussallen et al, 1999). “Water allocation is a means of dividing ...

  10. Spatial and temporal distribution of free-living protozoa in aquatic environments of a Brazilian semi-arid region

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    Maria Luisa Quinino de Medeiros


    Full Text Available Free-living protozoa organisms are distributed in aquatic environments and vary widely in both qualitative and quantitative terms. The unique ecological functions they exhibit in their habitats help to maintain the dynamic balance of these environments. Despite their wide range and abundance, studies on geographical distribution and ecology, when compared to other groups, are still scarce. This study aimed to identify and record the occurrence of free-living protozoa at three points in Piancó-Piranhas-Açu basin, in a semi-arid area of Rio Grande do Norte (RN state, and to relate the occurrence of taxa with variations in chlorophyll a, pH and temperature in the environments. Samples were collected in the Armando Ribeiro Gonçalves Dam, from two lentic environments upstream and a lotic ecosystem downstream. Sixty-five taxa of free-living protozoa were found. The Student's t-test showed significant inter-variable differences (p <0.05. Similar protozoan species were recorded under different degrees of trophic status according to chlorophyll a concentrations, suggesting the organisms identified are not ideal for indicating trophic level. We hypothesize that food availability, the influence of lentic and lotic systems and the presence of aquatic macrophytes influenced protozoan dynamics during the study period.


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    Full Text Available The replacement of natural vegetation by crop systems directly impacts the soil organic matter fractions. The objective of this study was to evaluate the total organic carbon (TOC and nitrogen (TN contents in different fractions of the soil organic matter (SOM of an Oxisol of the Brazilian semiarid region under different irrigated crops and different soil management systems. Seven treatments were evaluated, which consisted of two soil management systems (no - till and conventional tillage and three crops (maize, sunflower and sorghum, using as reference the soil under a native forest (NF. The summer crops preceded common bean crops in the autumn - winter. The total organic carbon content, total nitrogen, carbon content in humic substances and their constituents (fulvic acids, humic acids and humin and labile, non - labile and water - soluble carbon contents were evaluated two years and three months after the experiment implementation to determine the carbon lability (L lability index (LI, partitioning index (CPI and management index (CMI. The greatest carbon, nitrogen and organic matter contents in the soil surface layer (0.00 - 0.05 m were found in crops under no - till system (NTS, especially maize. The crops under NTS presented greater carbon content in humic substances than the conventional tillage system (CTS ones in the layer 0.05 - 0.10 m. The crops under NTS presented greater sustainability in the Brazilian semiarid region compared with those under CTS, as shown by their higher CMI in the soil surface layer.

  12. Waste biorefinery in arid/semi-arid regions. (United States)

    Bastidas-Oyanedel, Juan-Rodrigo; Fang, Chuanji; Almardeai, Saleha; Javid, Usama; Yousuf, Ahasa; Schmidt, Jens Ejbye


    The utilization of waste biorefineries in arid/semi-arid regions is advisable due to the reduced sustainable resources in arid/semi-arid regions, e.g. fresh water and biomass. This review focuses on biomass residues available in arid/semi-arid regions, palm trees residues, seawater biomass based residues (coastal arid/semi-arid regions), and the organic fraction of municipal solid waste. The present review aims to describe and discuss the availability of these waste biomasses, their conversion to value chemicals by waste biorefinery processes. For the case of seawater biomass based residues it was reviewed and advise the use of seawater in the biorefinery processes, in order to decrease the use of fresh water. Copyright © 2016 Elsevier Ltd. All rights reserved.

  13. Modelling radiation and energy balances with Landsat 8 images under different thermohydrological conditions in the Brazilian semi-arid region (United States)

    de C. Teixeira, Antônio H.; Leivas, Janice F.; Andrade, Ricardo G.; Hernandez, Fernando B. T.; Momesso, Franco R. A.


    Four Landsat 8 images were used together with a net of seven agro-meteorological stations for modelling the large-scale radiation and energy balances in the mixed agro-ecosystems inside a semi-arid area composed by irrigated crops and natural vegetation of the Petrolina municipality, Northeast Brazil, along the year 2014. The SAFER algorithm was used to calculate the latent heat flux (λE), net radiation (Rn) was acquired by the Slob equation, ground heat flux (G) was considered as a fraction of Rn and the sensible flux (H) was retrieved by residue in the energy balance equation. For classifying the vegetation into irrigated crops and natural vegetation, the SUREAL algorithm was applied to determine the surface resistance (rs) and threshold values for rs were used to characterize the energy fluxes from these types of vegetated surfaces. Clearly one could see higher λE from irrigated crops than from natural vegetation with some situations of heat horizontal advection increasing its values until 23% times larger than Rn, with respective average λE ranges of 5.7 (64% of Rn) to 7.9 (79% of Rn) and 0.4 (4% of Rn) to 4.3 (37% of Rn) MJ m-2 d-1. The corresponding H mean values were from 1.8 (18% of Rn) to 3.2 (28% of Rn) and 5.4 (60% of Rn) to 9.2 (94% of Rn) MJ m-2 d-1. Average G pixel values ranged from 0.3 to 0.4 MJ m-2 d-1, representing 3 and 4% of Rn for natural vegetation and irrigated crops, respectively.

  14. Enhanced cold-season warming in semi-arid regions

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    J. Huang


    Full Text Available This study examined surface air temperature trends over global land from 1901–2009. It is found that the warming trend was particularly enhanced, in the boreal cold season (November to March over semi-arid regions (with precipitation of 200–600 mm yr−1 showing a temperature increase of 1.53 °C as compared to the global annual mean temperature increase of 1.13 °C over land. In mid-latitude semi-arid areas of Europe, Asia, and North America, temperatures in the cold season increased by 1.41, 2.42, and 1.5 °C, respectively. The semi-arid regions contribute 44.46% to global annual-mean land-surface temperature trend. The mid-latitude semi-arid regions in the Northern Hemisphere contribute by 27.0% of the total, with the mid-latitude semi-arid areas in Europe, Asia, and North America accounting for 6.29%, 13.81%, and 6.85%, respectively. Such enhanced semi-arid warming (ESAW imply drier and warmer trend of these regions.

  15. Adaptation at Scale in Semi-Arid Regions | IDRC - International ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    People living in Africa and South Asia's semi-arid regions face challenges that hinder their economic growth and development. This project seeks to find proactive, longer-term approaches to climate change adaptation in these vulnerable regions, while helping locals manage existing risks. Short-term focus must shift. So far ...

  16. Uses of tree legumes in semi-arid regions

    Energy Technology Data Exchange (ETDEWEB)

    Felker, P.


    Uses of tree legumes in semi-arid and arid regions are reviewed. This review is divided into sections according to the following general use categories: fuels; human food; livestock food; to increase yields of crops grown beneath their canopies;and control of desertification. (MHR)

  17. Salma Hegga: Identifying adaptation strategies for semi-arid regions ...

    International Development Research Centre (IDRC) Digital Library (Canada)


    Feb 18, 2015 ... Together with teams from Southern, Western, and Eastern Africa, and India, she is working to assess vulnerability and adaptation to climate change in semi-arid regions. The research aims to identify adaptation strategies in these areas and determine which are the most effective. This research will also ...

  18. Reservoir in a Semi-Arid Region of Kenya

    African Journals Online (AJOL)

    a catchment devoid of roads in semi-arid region. Introduction due to the torrential nature of the rains. Formanyyears ... study took place, underground reservoirs serve as the main source of water for both domestic and ... slope steepness and the widths ofthe drains along the roads on the catchment as well as the valley which ...

  19. Arbuscular mycorrhizal fungi in Mimosa tenuiflora (Willd.) Poir from Brazilian semi-arid. (United States)

    de Souza, Tancredo Augusto Feitosa; Rodriguez-Echeverría, Susana; de Andrade, Leonaldo Alves; Freitas, Helena


    Many plant species from Brazilian semi-arid present arbuscular mycorrhizal fungi (AMF) in their rhizosphere. These microorganisms play a key role in the establishment, growth, survival of plants and protection against drought, pathogenic fungi and nematodes. This study presents a quantitative analysis of the AMF species associated with Mimosa tenuiflora, an important native plant of the Caatinga flora. AMF diversity, spore abundance and root colonization were estimated in seven sampling locations in the Ceará and Paraíba States, during September of 2012. There were significant differences in soil properties, spore abundance, percentage of root colonization, and AMF diversity among sites. Altogether, 18 AMF species were identified, and spores of the genera Acaulospora, Claroideoglomus, Dentiscutata, Entrophospora, Funneliformis, Gigaspora, Glomus, Racocetra, Rhizoglomus and Scutellospora were observed. AMF species diversity and their spore abundance found in M. tenuiflora rhizosphere shown that this native plant species is an important host plant to AMF communities from Brazilian semi-arid region. We concluded that: (a) during the dry period and in semi-arid conditions, there is a high spore production in M. tenuiflora root zone; and (b) soil properties, as soil pH and available phosphorous, affect AMF species diversity, thus constituting key factors for the similarity/dissimilarity of AMF communities in the M. tenuiflora root zone among sites. Copyright © 2016 Sociedade Brasileira de Microbiologia. Published by Elsevier Editora Ltda. All rights reserved.

  20. Estimation of evapotranspiration for different land covers in a Brazilian semi-arid region: A case study of the Brígida River basin, Brazil (United States)

    Santos, Celso Augusto Guimarães; Silva, Richarde Marques da; Silva, Alexandro Medeiros; Brasil Neto, Reginaldo Moura


    In this study, the Surface Energy Balance Algorithm for Land (SEBAL) was used to compute the surface albedo, vegetation indices (NDVI, SAVI and LAI), surface temperature, soil heat flux and evapotranspiration (ET) over two contrasting years (dry and wet) in the Brígida River basin, a semi-arid region of north-eastern Brazil. The actual ET was computed during satellite overpass and was integrated for 24 h on a pixel-by-pixel basis for the daily ET distribution. Due to the topographic effects, an attempt was also made to incorporate DEM information to estimate the net radiation. The land cover types identified in the watershed are cropland, bare land, dense canopy, grassland, and caatinga vegetation. In order to study the variation among the biophysical parameters and ET, two-way analysis of variance (ANOVA) was used. The ET calculated by SEBAL ranged between 2.46 and 6.87 mm/day for the dry year (1990) and 1.31 and 6.84 mm/day for the wet year (2009) for the river basin. The results showed that a reduction in vegetation cover is evident in the temporal and spatial analysis over the studied periods in the region and that these facts influence the values of the energy balance and ET. The results showed significant differences in the variables of land cover type and year at the probability level of 0.05 for all land cover types.


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    Full Text Available The Alismataceae (excluded Limnocharitaceae comprises twelve genera of herbaceous aquatic plants. Only two of its genera (Echinodorus and Sagittaria are native to the Neotropics. A survey of the species of Alismataceae confirmed the occurrence of four taxa of Sagittaria and eleven of Echinodorus from the semi-arid region of northeastern Brazil. Analytical keys to differentiate the genera and species are provided, as well as illustrations of their taxonomic characteristics and data on their geographical distribution. Echinodorus macrocarpus to be considered synonymous with E. pubescens. Echinodorus reticulatus is considered as a different species from E. longipetalus. There are five excluded taxa from the Brazilian semi-arid region: E. grandiflorus, E. macrophyllus, E. martii, E. bolivianus, and E. decumbens.

  2. Medicinal animals as therapeutic alternative in a semi-arid region of northeastern Brazil. (United States)

    Alves, Rômulo R N; Oliveira, Maria G G; Barboza, Raynner R D; Singh, Ranjay; Lopez, Luiz C S


    A number of animal species are offered by herbalists in markets throughout Brazil. Nevertheless, there is a general lack of information about this type of trade in the country. In this review, we report on the trade of medicinal animal species in a semi-arid region in northeastern Brazil. We gathered information from scientific articles on animal species used for medicinal purposes in that semi-arid region. The trade of medicinal animals comprises 59 species and the zootherapeutic products extracted from them, recommended for the treatment of 66 illnesses. Results demonstrate the existence of a multi-state trade network of medicinal animals. Some of the traded animals are listed in the Brazilian list of threatened species. This demonstrates the urgent need to consider zootherapy in the context of biodiversity conservation in Brazil. Our results reveal the importance of zootherapy as a therapeutic alternative and demonstrate the need of further studies on the subject. (c) 2009 S. Karger AG, Basel.

  3. Mitigation of Natural Hazards and Disasters. International Perspectives. Improving Access to Water Resources through Rainwater Harvesting as A Mitigation Measure. The Case of the Brazilian Semi-Arid Region

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    De Melo Branco, A.; Suassuna, J.; Adler Vainsencher, S. [Independent Consultant, Rua Cardeal Arcoverde, 100/701, Gracas, Recife, Pernambuco (Brazil)


    This paper focuses on the importance of rainwater harvesting to mitigate the scarcity of water in the semi-arid region of Brazil. It is a case study about the Million Cisterns Project, an initiative developed by NGOs with the support of Brazilian Federal Government Institutions and international funding organizations. The project is innovative in a series of ways when compared to mitigation measures previously implemented by the government. Instead of focussing on short-term, top-down, palliative measures based on the construction of dams and wells, it focuses on low cost, bottom-up, long-term measures and, most importantly, it involves an educational component. Thus, the provision of water is closely related to the empowerment of the most destitute population and this leads to the sustainability of the actions. The case study serves to illustrate the relevance of the partnership between grassroots organizations and governmental institutions in the context of mitigation.

  4. Mathematical Modeling for Evaluation of Field Water Supply Alternatives (Arid and Semi-Arid Regions). (United States)


    EVALUATION OF FIELD WATER SUPPLY ALTERNATIVES ( Arid and Semi - Arid Regions) FINAL REPORT eJ. M. Morgan, Jr. J. R. Sculley LV. J. Ciccone* aD. K. Jamison J. W...Final Report Water Supply Alternatives 1 August 79-31 January 81 ( Arid and Semi - Arid Regions) 6. PERFORMING ORG. REPORT NUMBER AUTHOR(S) S. CONTRACT...CLAUIFICATION OF THIS PAGE(Whan Data Entesed) 20. (Cont’d.) ~issues pertinent to the production of water in an arid or semi - arid environment, and, finally

  5. Droughts and governance impacts on water scarcity: an~analysis in the Brazilian semi-arid

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    A. C. S. Silva


    Full Text Available Extreme events are part of climate variability. Dealing with variability is still a challenge that might be increased due to climate change. However, impacts of extreme events are not only dependent on their variability, but also on management and governance. In Brazil, its semi-arid region is vulnerable to extreme events, especially droughts, for centuries. Actually, other Brazilian regions that have been mostly concerned with floods are currently also experiencing droughts. This article evaluates how a combination between climate variability and water governance might affect water scarcity and increase the impacts of extreme events on some regions. For this evaluation, Ostrom's framework for analyzing social-ecological systems (SES was applied. Ostrom's framework is useful for understanding interactions between resource systems, governance systems and resource users. This study focuses on social-ecological systems located in a drought-prone region of Brazil. Two extreme events were selected, one in 1997–2000, when Brazil's new water policy was very young, and the other one in 2012–2015. The analysis of SES considering Ostrom's principle "Clearly defined boundaries" showed that deficiencies in water management cause the intensification of drought's impacts for the water users. The reasons are more related to water management and governance problems than to drought event magnitude or climate change. This is a problem that holdup advances in dealing with extreme events.

  6. Karst characterization in a semi-arid region using gravity, seismic, and resistivity geophysical techniques.

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    Barnhart, Kevin Scott


    We proposed to customize emerging in situ geophysical monitoring technology to generate time-series data during sporadic rain events in a semi-arid region. Electrodes were to be connected to wireless \

  7. Variabilidade genética do umbuzeiro no Semi-Árido brasileiro, por meio de marcadores AFLP Genetic variability of umbu trees in Brazilian Semi-Arid region, based on AFLP markers

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    Carlos Antonio Fernandes Santos


    Full Text Available O objetivo deste trabalho foi avaliar a distribuição da variabilidade genética do umbuzeiro (Spondias tuberosa, no Semi-Árido brasileiro, por meio de marcadores AFLP, para subsidiar estratégias de prospecção e conservação da espécie. Foram analisados 68 indivíduos de umbuzeiro de 15 ecorregiões, pelo dendrograma UPGMA e pela dispersão em escala multidimensional (MDS, com o coeficiente de Jaccard de 141 bandas polimórficas de AFLP. A análise da variância molecular foi realizada pela decomposição total entre e dentro das regiões ecogeográficas. O dendrograma apresentou valor cofenético de 0,96, e o gráfico MDS apresentou 0,25 para a falta de ajustamento. A variabilidade genética do umbuzeiro foi estimada em 0,3138, o que indica grande variação entre os grupos de indivíduos. Agrupamentos específicos foram observados em seis regiões ecogeográficas, enquanto nas demais regiões observaram-se pares entre alguns indivíduos, sem formação de agrupamentos específicos por local de amostragem, o que indica que a variabilidade genética do umbuzeironão está uniformemente distribuída no Semi-Árido. Sugerem-se estratégias para o estabelecimento de maior número de áreas para conservação in situ ou amostragens de menor número de indivíduos, em várias unidades de paisagens, para conservação ex situ da variabilidade genética do umbuzeiro.The objective of this work was to evaluate the genetic variability distribution of umbu tree (Spondias tuberosa, within Brazilian Semi-Arid region, based on AFLP markers, in order to suggest prospecting and preservation strategies for this species. Sixty-eight umbu trees of 15 ecogeographic regions were analyzed for 141 polymorphic AFLP bands, through the UPGMA dendrogram and the multidimensional scaling (MDS, based on Jaccard's coefficient . Analysis of molecular variance was accomplished by total decomposition among and within ecogeographic regions. The dendrogram presented co

  8. New Possibilities for High-Resolution, Large-Scale Ecosystem Assessment of the World's Semi-Arid Regions (United States)

    Burney, J. A.; Goldblatt, R.


    Understanding drivers of land use change - and in particular, levels of ecosystem degradation - in semi-arid regions is of critical importance because these agroecosystems (1) are home to the world's poorest populations, almost all of whom depend on agriculture for their livelihoods, (2) play a critical role in the global carbon and climate cycles, and (3) have in many cases seen dramatic changes in temperature and precipitation, relative to global averages, over the past several decades. However, assessing ecosystem health (or, conversely, degradation) presents a difficult measurement problem. Established methods are very labor intensive and rest on detailed questionnaires and field assessments. High-resolution satellite imagery has a unique role semi-arid ecosystem assessment in that it can be used for rapid (or repeated) and very simple measurements of tree and shrub density, an excellent overall indicator for dryland ecosystem health. Because trees and large shrubs are more sparse in semi-arid regions, sub-meter resolution imagery in conjunction with automated image analysis can be used to assess density differences at high spatial resolution without expensive and time-consuming ground-truthing. This could be used down to the farm level, for example, to better assess the larger-scale ecosystem impacts of different management practices, to assess compliance with REDD+ carbon offset protocols, or to evaluate implementation of conservation goals. Here we present results comparing spatial and spectral remote sensing methods for semi-arid ecosystem assessment across new data sources, using the Brazilian Sertão as an example, and the implications for large-scale use in semi-arid ecosystem science.

  9. Tropical Warm Semi-Arid Regions Expanding Over Temperate Latitudes In The Projected 21st Century (United States)

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


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

  10. The characterisation of rainfall in the arid and semi-arid regions of ...

    African Journals Online (AJOL)

    of rainfall. Although it is one of the most drought-hit countries in the world, almost no study has ever been conducted in characterising the rainfall pattern of the arid and semi-arid regions of Ethiopia. In this study, rainfall data of the past 50 years was used to study the basic statistical characteristics of the rainfall of this region.

  11. Greenhouse technology for cultivation in arid and semi-arid regions

    NARCIS (Netherlands)

    Baeza Romero, Esteban; Kacira, M.


    Greenhouses have expanded from Northern areas to other climatic regions in the world, including arid and semi-arid regions. The main limiting factors for greenhouse cultivation in such areas are the high ambient temperatures with low humidity (sometimes with high humidity in coastal areas), typical

  12. Watergy, towards a closed greenhouse in semi-arid regions-Experiment with a Heat Exchanger

    NARCIS (Netherlands)

    Speetjens, S.L.; Walle, van der T.; Straten, van G.; Stigter, J.D.; Janssen, H.J.J.; Gieling, T.H.


    Water resources are diminishing in many (semi) arid regions, thus becoming a concern in the (near) future. Desalination of brackish or salt water can be a good solution to provide water for agriculture and human consumption. The Watergy project proposes an integrated system in which plants and fresh

  13. Woody plants in agro-ecosystems of semi-arid regions

    NARCIS (Netherlands)

    Breman, H.; Kessler, J.J.


    A quantitative analysis of the role of woody plants in semi-arid regions, focusing on the Sahel and Sudan zones in West-Africa, is given for the assessment of their benefits in agro-sylvopastoral land-use systems with productive and sustainability objectives.

  14. Evaluating rainwater harvesting systems in arid and semi-arid regions

    NARCIS (Netherlands)

    Ammar, Adham Ali


    Rainwater harvesting (RWH) is an ancient traditional technology practised in many parts of the world, especially in arid and semi-arid regions (ASARs). ASARs represent 40% of the earth’s land surface and are characterised by low average annual rainfall and uneven temporal and spatial

  15. Prevalence of bovine coccidial infection in the semi-arid region of ...

    African Journals Online (AJOL)

    A study was undertaken on the prevalence of coccidial infections of bovine in the semi-arid region of north-eastern Nigeria. Of the 147 bovine faecal samples examined, 108 (62.1%) had coccidial oocysts. According to breeds, however, no statistical variation (p>0.05) existed in the prevalence of infection between the ...

  16. Semi-arid Northeast Brazil: integrated modelling of regional development and global change impacts

    NARCIS (Netherlands)

    Krol, Martinus S.; Fuhr, Dagmar; Döring, Andreas; Unruh, Jon D.; Krol, Maarten S.; Kliot, Nurit


    Societies in semi-arid areas in developing regions are amongst those most vulnerable to climate variability and potentially most vulnerable to climate change. The vulnerability to climate variability emerges from a combination of the level of availability of natural resources and the human

  17. Is annual recharge coefficient a valid concept in arid and semi-arid regions? (United States)

    Cheng, Yiben; Zhan, Hongbin; Yang, Wenbin; Dang, Hongzhong; Li, Wei


    Deep soil recharge (DSR) (at depth greater than 200 cm) is an important part of water circulation in arid and semi-arid regions. Quantitative monitoring of DSR is of great importance to assess water resources and to study water balance in arid and semi-arid regions. This study used a typical bare land on the eastern margin of Mu Us Sandy Land in the Ordos Basin of China as an example to illustrate a new lysimeter method of measuring DSR to examine if the annual recharge coefficient is valid or not in the study site, where the annual recharge efficient is the ratio of annual DSR over annual total precipitation. Positioning monitoring was done on precipitation and DSR measurements underneath mobile sand dunes from 2013 to 2015 in the study area. Results showed that use of an annual recharge coefficient for estimating DSR in bare sand land in arid and semi-arid regions is questionable and could lead to considerable errors. It appeared that DSR in those regions was influenced by precipitation pattern and was closely correlated with spontaneous strong precipitation events (with precipitation greater than 10 mm) other than the total precipitation. This study showed that as much as 42 % of precipitation in a single strong precipitation event can be transformed into DSR. During the observation period, the maximum annual DSR could make up 24.33 % of the annual precipitation. This study provided a reliable method of estimating DSR in sandy areas of arid and semi-arid regions, which is valuable for managing groundwater resources and ecological restoration in those regions. It also provided strong evidence that the annual recharge coefficient was invalid for calculating DSR in arid and semi-arid regions. This study shows that DSR is closely related to the strong precipitation events, rather than to the average annual precipitation, as well as the precipitation patterns.

  18. Estratégias para o desenvolvimento de novas cultivares de mangueira para o semiárido brasileiro Mango strategies to develop new varieties to the Brazilian tropical semi-arid region

    Directory of Open Access Journals (Sweden)

    Carlos Antonio Fernandes Santos


    Full Text Available A mangueira é uma das principais fruteiras comerciais no Semiárido brasileiro, sendo que a cultivar Tommy Atkins ocupa 85% da área total cultivada com a cultura. O objetivo deste trabalho foi avaliar o emprego de estratégias para reduzir o período juvenil e as trabalhosas polinizações manuais em mangueira, de forma a acelerar o desenvolvimento de novas cultivares da espécie para o Semiárido brasileiro. Foram identificadas plantas isoladas das cultivares Haden e Espada dentro de plantios comerciais da cultivar Tommy Atkins, numa fazenda exportadora de manga, em Petrolina-PE. Mudas das progênies foram transplantadas com seis meses de idade para o campo. O manejo para a indução floral foi realizado com poda, controle da irrigação e aplicação de Paclobutrazol e nitrato de potássio. O DNA extraído das progênies e parentais foi submetido a análises com marcadores microssatélites publicados para Mangifera indica L. O manejo combinado foi eficiente para induzir a floração e a frutificação em, aproximadamente, 70% das progênies após dois anos e meio de transplantio. Dos 94 indivíduos analisados com três microssatélites, 83% foram identificados como híbridos entre 'Haden' x 'T. Atkins'. Dos 401 indivíduos analisados com um microssatélite, 10% foram identificados como híbridos entre 'Espada' x 'T. Atkins'. A estratégia adotada foi eficiente para reduzir o período juvenil e evitar os trabalhosos cruzamentos manuais em mangueira, sendo que o desenvolvimento de novas cultivares da espécie para a região pode ser concluído com oito a dez anos, incluindo as rigorosas avaliações agronômicas.Mango is one of the most important fruit crop in the Brazilian Semi-Arid region. The cultivar Tommy Atkins has been grown in 85% of total area dedicated to this crop. The goal of this research was to evaluate strategies to reduce the juvenile period and to replace the laborious hand pollinization in order to accelerate the development

  19. Dynamic of epigeous macrofauna under organic soil management in the Brazilian semi-arid regionDinâmica da macrofauna epígea sob manejo orgânico do solo no semi-árido brasileiro

    Directory of Open Access Journals (Sweden)

    Márcio Sampaio Pimentel


    Full Text Available Soil macrofauna is responsible for soil fertility through cycling of nutrients, tillage and fragmentation of organic matter, as well as through the association between groups of fauna with conserved and/or degraded pedoenvironments. Nevertheless, under the conditions of the Brazilian semi-arid region, there is little information about this resource. The objective of this study was to evaluate the epigeous macrofauna in successive cropping using previous green manure and subsequent planting of melon (Cucumis melo L. in Juazeiro county, Bahia, Brazil. Sampling dates were undertaken in November 2007 and February, April and July 2008, using traps containing 4 % formaldehyde for seven days in plots of 64 m2. Results obtained indicate that there is no difference among the treatments with mixed cover crops, and epigeous macrofauna is influenced by the time of collection. Diversity and uniformity are inversely correlated with total density of epigeous macrofauna. Diversification of plant species favors the increase of diversity and uniformity of epigeous macrofauna. Formicidae, followed by Isopoda, Coleoptera and Oligochaeta are the groups of fauna most numerous in the areas. A macrofauna do solo é responsável pela melhoria da fertilidade do solo através da ciclagem de nutrientes, revolvimento e fragmentação da matéria orgânica, como também, pela associação entre grupos de fauna com pedoambientes conservados e/ou degradados. No entanto, nas condições de semi-árido brasileiro pouca informação se tem a respeito deste recurso. Neste sentido, na região do sub-médio do Rio São Francisco, pólo de desenvolvimento da agricultura irrigada objetivou-se avaliar a macrofauna epígea em sucessão cultural utilizando prévia adubação verde e subseqüente plantio de melão (Cucumis melo L.. As coletas foram realizadas em novembro de 2007 e fevereiro, abril e julho de 2008 no município de Juazeiro, BA, utilizando armadilhas contendo formol 4

  20. Radioecological characterization of a uranium mining site located in a semi-arid region in Brazil

    Energy Technology Data Exchange (ETDEWEB)

    Fernandes, Horst M. [Instituto de Radioprotecao e Dosimetria, Environmental Impact Assessment, Av. Salvador Allende s/n - Recreio, 22780-160, Rio de Janeiro (Brazil) and University of Central Florida (United States)]. E-mail:; Lamego Simoes Filho, F. Fernando [Instituto de Radioprotecao e Dosimetria, Environmental Impact Assessment, Av. Salvador Allende s/n - Recreio, 22780-160, Rio de Janeiro (Brazil); Perez, Valeska [Instituto de Engenharia Nuclear (Brazil); Franklin, Mariza Ramalho [Instituto de Radioprotecao e Dosimetria, Environmental Impact Assessment, Av. Salvador Allende s/n - Recreio, 22780-160, Rio de Janeiro (Brazil); Gomiero, Luiz Alberto [Industrias Nucleares do Brasil (Brazil)


    The work presents the radioecological characterization of the new Brazilian uranium mining and milling site located in a semi-arid region of the country. The process characterization demonstrated that in heap leach plants most of the {sup 226}Ra remains in the leached ore. Despite the potential higher availability of radium isotopes in the soils of the studied region the lack of precipitation in that area reduces the leaching/mobilization of the radionuclides. High {sup 226}Ra and {sup 228}Ra concentrations were found in manioc while {sup 21}Pb was significant in pasture. It was suggested that a range from 10{sup -3} to 10{sup -1} may conveniently encompass most of the transfer factors (TF) values for soil/plant systems (i.e. involving different cultures, different soils and natural radionuclides). Impacts due to aerial transportation of aerosols and radon generated in the mining were proved to be minimal and restricted to an area not greater than 15 km{sup 2}. Finally, uranium complexation by carbonates was shown to be the main mechanism responding for the elevated radionuclide concentration in groundwater.

  1. Temperature variations in a housing of the semi-arid region of Djelfa (Algeria)

    Energy Technology Data Exchange (ETDEWEB)

    Ettoumi, F.Y.; Adane, A.E.H. [Universite de Sciences et Technologie Houari Boumediene, Faculte de Genie Electrique, Alger (Algeria); Messen, N. [C.N.R.B.-BP, Wilaya de Djelfa (Algeria); Sauvageot, H. [Universite Paul Sabatier, Toulouse (France). Lab. d' Aerologie


    Temperature variations are analysed for two areas of Algeria, lying in a semi-arid region and near the West Coast, respectively, the Djelfa and Oran areas. This analysis mainly consists in computing the temperature deviations with respect to the reference levels of 18{sup o}C and 25{sup o}C. Their time variations are then studied. When summing the temperature deviations per month, the amount of energy, expressed in degree hour for each month of the year, necessary to heat and cool the houses during cold weather and hot periods, respectively, is obtained. An economic study of construction material efficiency is associated with the computation of the temperature deviations and applied to housing in semi-arid regions. It is shown that cheap traditional materials having greater thermal inertia can advantageously be used for housing constructions in these regions.(author)

  2. Statistical Change Detection in Dust Storm Frequency Across Arid and Semi-arid Regions of Iran (United States)

    Modarres, R.; Sadeghi, S.; Sarhadi, A.


    Arid and semi-arid regions cover 60% of Iran which are surrendered by two major mountains in the north and west of the country. This central region of Iran not only receives very low amount of rainfall but also suffers from high human induced intense land degradation. These conditions have been leading to frequent dust storms which have been influencing soil erosion and population migration. In this study the spatial and temporal change in dust storm occurrence is investigated over arid and semi-arid region of Iran. The annual number of dust storms was collected from 22 stations for 1951-2010 period and nonparametric methods were used to detect both monotonic trend and change point in these annual time series. The number of dust storm increases from the northern reigns to the south eastern territories where climate conditions are influenced by rainfall reduction and increasing drought frequency. The trend assessment indicate negative trend of dust storm occurrence in the north and increasing trend for the southeastern territories of the region. The change point detection method also indicates the 1970 and 1980 decades have most frequent and significant change points of dust storm appearance over arid and semi-arid regions of Iran. Using Wilcoxon, Levene and Kolmogorov Smirnov tests reveal statistically significant shift in the mean, variance and frequency distribution of dust storm occurrence after the change point.

  3. The impacts of precipitation on land- atmosphere interaction over the semi-arid Loess Plateau region (United States)

    WANG, G.; Huang, J.


    To understand the impacts of precipitation on land-atmosphere interactions over semi-arid regions, 6-year continuous measurements data in situ were analyzed to investigate the influence of precipitation on soil moisture, evapotranspiration, energy partitioning and plant growing over Loess Plateau in northwest China. Results show that annual precipitation had obvious inter-annual variability, and the variation of soil moisture; evaporation and CO2 flux were very consistently with the annual cycle and intensity of precipitation. Soil moisture is the key participant in land-atmosphere interaction. However, as the water shortage and disconnected from water table over the semi-arid region, it is much more sensitive with precipitation compensation and evaporation feedbacks. Soil water can cooling the near surface air temperature by evaporation (latent heat flux), and also as the main energy partitioning consumer of net radiation in humid area or pluvial period in arid area, yet it was water limited in arid and semi-arid region, sensible heat flux predominated net radiation for enhancing the surface air temperature. We also found that soil moisture profile significantly affected the plant physiology, which was also consistent with the annual cycle and intensity of precipitation.

  4. Cyanobacterial occurrence and detection of microcystins and saxitoxins in reservoirs of the Brazilian semi-arid

    Directory of Open Access Journals (Sweden)

    Jessica Roberts Fonseca


    Full Text Available Aim:The rapid spread of cyanobacteria in water sources and reservoirs has caused serious environmental damage and public health problems, and consists in a problem that challenges the institutions responsible for providing water to the population. In this study, the quantification of microcystin, saxitoxins and cyanobacteria levels was performed over 3 years in the semi-arid reservoirs of Rio Grande do Norte (Brazil. In addition, we analyzed the seasonal distribution of cyanotoxins and the percentage of cyanobacteria and cyanotoxins which were above the limit established by Brazilian law.MethodsThe study was conducted between 2009 and 2011 in four dams with six sites: Armando Ribeiro Gonçalves (ARG in Itajá, San Rafael (SR and Jucurutu; Passagem das Traíras (PT; Itans and Gargalheiras (GARG. Cyanobacteria presence were quantified and identified and the presence of microcystins (MCYs and saxitoxins (STXs was investigated by ELISA.ResultsThe densities of cyanobacteria were found to be above the permitted in 76% of cases. The ELISA results showed that of the 128 samples analyzed, 27% were above the maximum allowed by the Brazilian Ministry of Health Order 2914/2011. A seasonal pattern for the presence of MCYs was found (0.00227 to 24.1954 µg.L–1, with the highest values in the rainy season. There was no clear seasonal pattern for STXs (0.003 to 0.766 µg.L–1.ConclusionsThis study showed the importance of establishing a water quality monitoring for human consumption and its potability standards since the concentration of MCYs in some samples was above the maximum limit allowed by Brazilian law, thus posing a risk to public health since the conventional water treatment is not able to eliminate these potent hepatotoxins.


    Directory of Open Access Journals (Sweden)

    Carla da Silva Sousa


    Full Text Available is an exclusively Brazilian biome with areas in accentuated process of desertification. Arbuscularmycorrhizal fungi (AMF act in plant succession by favoring the establishment of plant species typical ofsuccessional stages and by accelerating recovery leading to a climax stage. The objective of the present workwas to evaluate the occurrence and diversity of AMF in successional stages of caatinga in the semi-aridregion of Paraíba State. Experimental plots (30 x 60 m were delimitated in 2007 in areas corresponding todifferent caatinga successional stages: early caatinga succession (natural revegetation during the previous15 years; intermediate (natural revegetation for about 35 years; late (mature caatinga with more than50 years without major disturbances; and also in pasture areas fenced and protected to represent the initialphase of succession. Plots of all four stages were implemented with three replicates. Soil and root sampleswere collected in the experimental plots, from the 0-15 cm soil layer in the dry and in the rainy seasons.All areas presented low infectivity potential suggesting that the introduction of mycorrhizal seedlings mayaccelerate the process of revegetation of degraded soils in this region. Except for the areas of late stage, theglomalin reservoirs increased along with the advancement of the succession process. Areas in the late stageof succession presented greater richness of AMF species, indicating that the establishment of the vegetationalso exerts a significant effect in the fungal community. Glomus and Acaulospora species were predominantin both seasons, possibly because they are well adapted to semi-arid conditions

  6. Spatial Variability of Surface and Subsurface Saturated Hydraulic Conductivity in a Semi-Arid Region: Results from a Field Campaign


    Becker, Rike


    The accurate estimation of saturated hydraulic conductivity (Ks) is of high relevance to correctly reproduce water movement in hydrological simulations. Yet, estimation of Ks is challenging particularly in semi-arid regions with particular soil surface characteristics like crusting and sealing. This study presents results of a field campaign in the semi-arid Walnut Gulch Experimental Watershed, Arizona (US), where surface and subsurface Ks measurements were undertaken across the watershed. Re...

  7. A Methodology to Assess and Evaluate Rainwater Harvesting Techniques in (Semi-)Arid Regions (United States)

    Ali, Ammar; Riksen, Michel; Ouessar, Mohamed; Ritsema, Coen


    Arid and semi-arid regions around the world are generally facing water scarcity problems due to lack of precipitation and unpredictable rainfall patterns. For thousands of years rainwater harvesting (RWH) techniques have been applied to cope with water scarcity. Many researchers have presented and applied different methodologies for determining suitable sites and techniques for RWH. However, there is still little attention given to evaluation of the performance of RWH structures. The aim of this research was to design a scientifically-based and generally applicable methodology to evaluate and assess the performance of existing RWH techniques in (semi-) arid regions. The methodology takes engineering, biophysical, and socio-economic criteria into account to assess the performance of RWH using the Analytical Hierarchy Process (AHP) supported by Geographic Information System (GIS). The Oum Zessar watershed in south-eastern Tunisia is used as a case study site to test this evaluation tool. The performance of 58 RWH locations (14 jessour and 44 tabias) in three main sub-catchments of Oum Zessar watershed were assessed and evaluated. Based on the criteria selected, 60performance, 36received good performance scores. The results very accurately represent the real performance of each site. This integrated methodology, which is highly flexible, saves time and costs, and is easy to adapt in different regions, provides a scientifically based analytical tool to support designers and decision makers aiming to improve the performance of existing and new RWH sites.

  8. Evaluation of Solar Chimney Power Plant in Semi-Arid Region of Nigeria

    Directory of Open Access Journals (Sweden)

    G. M. Ngala


    Full Text Available Solar chimney power plant (SCPP is a renewable energy facility that converts the potential energy in the Sun into kinetic energy and subsequently into electrical energy. The problem of global warming and electricity generation/distribution in Nigeria cannot be over emphasized; however with the vast land in the semi arid region and the potentials of the above technology, high prospects exist for solar chimney as it is a decentralized form of power generation. The aim of this paper was to theoretically evaluate the performance of the solar chimney power plant in semi-arid region of Nigeria, and estimate the amount of electrical energy that can possibly be generated. A mathematical model was used to estimate the amount of power generated, and determine the relationship between various meteorological and physical factors to the power produced. A solar chimney power plant with collector diameter of 700 m and chimney height of 700 m can produce up to 3000 MW of electricity.

  9. New species and records of Anacroneuria (Plecoptera: Perlidae) from the northeastern semi-arid region of Brazil. (United States)

    Duarte, Tácio; Lecci, Lucas Silveira


    The genus Anacroneuria is widely distributed in the Neotropical Region. There are about 80 species listed from Brazil, five of which are recorded from the northeastern semi-arid region of Brazil, an area characterized by irregular and low precipitation. Examination of adult Anacroneuria material from this including areas of Caatinga desert vegetation and Atlantic forest revealed two new species records, A. debilis (Pictet) and A. terere Righi-Cavallaro & Lecci. Additionally, two new species, A. calori n. sp. and A. singela n. sp., are described from this material. These new records and new species reflect a major effort to document the biodiversity of the aquatic insects of the northeastern semi-arid region of Brazil by the Research Program in Semi-arid Biodiversity.

  10. Amphibian and reptile biodiversity in the semi-arid region of the municipality of Nopala de Villagrán, Hidalgo, Mexico


    Roth-Monzón, Andrea J.; Mendoza-Hernández, Andrés Alberto; Flores-Villela, Oscar


    Current global changes are putting both biodiversity and the processes that depend on it at risk. This is especially true for semi-arid regions and the flagship groups that inhabit them, such as amphibians and reptiles. Semi-arid regions are often thought to have lower biodiversity and thus have been overlooked, resulting in the underestimation of their biological richness. Therefore, the aim of this study was to conduct an inventory of amphibians and reptiles in the semi-arid municipality of...

  11. Acupunctural Afforestation for Desertification Mitigation over Semi-Arid Regions in East Asia (United States)

    Myoung, B.; Choi, Y.; Park, S. K.


    Desertification over the arid/semi-arid regions in East Asia and dust transports from the regions have been serious concerns for the societies not only in adjacent Asian countries but also in the western US. One of the strategies for desertification mitigation is tree planting over the semi-arid areas. However, unless the newly planted vegetation changes the feedback characteristics between land-surface and the atmosphere, the impact is not profound and effective for a long time. Here we show afforestation effects on the coupling strength between the land-surface and atmosphere, measured by the monthly anomalies of precipitation and evapotranspiration. The coupling strength is an important parameter to diagnose the aridity of a region since the stronger coupling strength is indicative of the higher vulnerability of the local climate to droughts. Simulations of a regional vegetation-climate coupled model reveal that afforestation substantially modulates local coupling strength mainly through controlling variability of evapotranspiration. The coupling strength decreases most significantly with an increase of unit vegetation fraction over the northern and central China including Manchurian Plains and highly populated areas of Beijing and Tianjin. The coupling characteristics of these regions are expected to reduce the occurrence of extreme weather events such as droughts by alleviating positive responses of the surface to precipitation deficit. Therefore, afforestation concentrated on these regions, which is called "acupunctural afforestation", may most effectively contribute to desertification mitigation than other regions by attenuating mechanisms maintaining warm season droughts. This study suggests that our attention should be paid to understanding the coupling strength between land and the atmosphere for desertification mitigation.

  12. Rainfall reductions over Southern Hemisphere semi-arid regions: the role of subtropical dry zone expansion. (United States)

    Cai, Wenju; Cowan, Tim; Thatcher, Marcus


    Since the late 1970s, Southern Hemisphere semi-arid regions such as southern-coastal Chile, southern Africa, and southeastern Australia have experienced a drying trend in austral autumn, predominantly during April and May. The rainfall reduction coincides with a poleward expansion of the tropical belt and subtropical dry zone by around 2°-3° in the same season. This has raised questions as to whether the regional rainfall reductions are attributable to this poleward expansion. Here we show that the impact of the poleward subtropical dry-zone shift is not longitudinally uniform: a clear shift occurs south of Africa and across southern Australia, but there is no evidence of a poleward shift in the southern Chilean sector. As such, a poleward shift of climatological April-May rainfall can explain most of the southeastern Australia rainfall decline, a small portion of the southern Africa rainfall trend, but not the autumn drying over southern Chile.

  13. Weed community and growth under the canopy of trees adapted to the brazilian semi-arid region Comunidade e crescimento de plantas daninhas sob a copa de árvores adaptadas ao semi-árido brasileiro

    Directory of Open Access Journals (Sweden)

    P.S.L. Silva


    Full Text Available The objectives of this work were to evaluate the floristic composition and dry biomass of weeds under the canopy of seven perennial species adapted to the Semi-Arid region of Brazil, and correlate these characteristics with growth traits of the perennial species. The following perennial species were evaluated in two experiments (E1 and E2: mesquite (Prosopis juliflora, jucá (Caesalpinia ferrea, white popinac (Leucaena leucocephala, mofumbo (Combretum leprosum, neem (Azadirachata indica, sabiá (Mimosa caesalpiniaefolia and tamarind (Tamarindus indica. In E1, the seven species were evaluated in a random block design with four replicates and nine plants per plot. In E2, evaluation comprised four species (mesquite, jucá, white popinac, and tamarind in a random block design with eight replicates and nine plants per plot. A circle with an area of 1.77 m² was established around the trunk of each plant, two years after they were transplanted to the permanent location. The weeds collected within this circle were cut even with the ground, classified and weighed. At this time, plant height, and crown and stem diameters were evaluated in all trees of each plot. In E1 there were no differences between tree species as to weed frequency under their canopies; however, weed growth was smaller under the canopy of sabiá trees. Mesquite and sabiá had the greatest plant height and crown diameter means, but only sabiá had the greatest stem diameter. In E2, the perennial species were not different with regard to weed frequency and growth under their canopies, but mesquite had the greatest growth, as measured by plant height (with significant results for jucá as well and crown and stem diameter.Os objetivos deste trabalho foram avaliar a composição florística e a biomassa de plantas daninhas sob a copa de sete espécies perenes adaptadas à região semi-árida do Brasil, e correlacionar essas características com características do crescimento das esp

  14. Analyzing Land Surface Evapotranspiration in Semi-Arid Regions Using A Modified Triangle Method (United States)

    Zhang, H.; Gorelick, S.; Avisse, N.; Tilmant, A.; Rajsekhar, D.; Yoon, J.


    Difficulty in estimating spatially variable actual evapotranspiration continues to pose an obstacle to regional water resources planning and management. The widely-used satellite-based triangle methods require similar elevations across the domain, an assumption that is often doubtful at the regional scale. This study presents a modified triangle method based on the discretization of digital elevation models. It disaggregates the domain into a number of overlapping elevation zones and constructs a temperature-vegetation triangle for each elevation zone. The wet edge is determined using a linear temperature lapse rate derived from annual average air temperature observations across weather stations at different elevations. Dry and wet edges are extended to a hypothetical "fully-vegetated" pixel, and evapotranspiration capacity varies on both edges. This method addresses elevation variation and water stress in semi-arid environments, without altering land surface temperature and elevation data. We demonstrate this method in northwestern Jordan with MODIS data from 2009. Results show that this method is an effective approach to correct overestimation by a traditional triangle method and underestimation by the MODIS evapotranspiration product over both natural vegetated and irrigated areas. In contrast to previous triangle algorithms in which the domain-wide lump temperature and NDVI data could mask the underlying signal and efficacy of triangle methods, this method represents a semi-distributed scheme to discretize the altitude effects on triangle methods and provides a template to address the heterogeneity of other physical factors. It constitutes an essential step towards the satellite-based quantification of irrigation water use and effective water resources management in Jordan as well as other semi-arid regions with high freshwater vulnerability.

  15. [Effect of Biochar on Soil Greenhouse Gas Emissions in Semi-arid Region]. (United States)

    Guo, Yan-liang; Wang, Dan-dan; Zheng, Ji-yong; Zhao, Shi-wei; Zhang, Xing-chang


    This study aimed to investigate the effects of biochar addition on the emission of greenhouse gases from farmland soil in semi-arid region. Through an in-situ experiments, the influence of sawdust biochar(J) and locust tree skin biochar (H) at three doses (1%, 3%, and 5% of quality percentage) on C2, CH4 and N2O emissions were studied within the six months in the south of Ningxiaprovince. The results indicated that soil CO2 emission flux was slightly increased with the addition doses for both biochars, and the averaged CO2 emission flux for sawdust and locust tree skin biochar was enhanced by 1. 89% and 3. 34% compared to the control, but the difference between treatments was not statistically significant. The soil CH4 emission was decreased with the increasing of biochar doses, by 1. 17%, 2. 55%, 4. 32% for J1, J3, J5 and 2. 35%, 5. 83%, 7. 32% for H1, H3, H5, respectively. However, the difference was statistically significant only for J5, H3 and H5 treatments (P effect on soil N2O emission. Our study indicated that the biochar has no significant influence on soil CO2 and N2O emissions within six months in semi-arid region and can significantly influence soil CH4 emissions (P < 0. 05). As for biochar type, the locust tree skin biochar is significantly better than the sawdust biochar in terms of restraining CH4 emission(P = 0. 048).

  16. Quality of Life of Post-Mastectomy Women Living in a Semi-Arid Region of Brazil. (United States)

    Araújo Neto, Emídio A; Alves, Beatriz C A; Gehrke, Flávia de S; Azzalis, Ligia A; Junqueira, Virginia C B; Sousa, Luiz Vinicius de A; Adami, Fernando; Fonseca, Fernando L A


    Health is the major reference regarding quality of life; when it comes to breast cancer in particular, the loss of a breast traumatically affects a woman's life, reflecting on her quality of life. Recognizing this problem, our aim was to investigate the quality of life of women who live in a semi-arid region of Brazil after breast cancer mastectomy. In this exploratory, transversal and observational study, a Brazilian variantof the shorter version of the original instrument from the World Health Organization Quality of Life (WHOQOL-BREF), applied in the study population, was analyzed and their socio-demographic profile was obtained. The sample was composed of 50 mastectomized women. The 50 included patients comprised women at a mean age of 54 years. Most of them had finished elementary school, and their average income was one Brazilian minimum monthly wage. Regarding the data related to quality of life, the highest score was found in the social relationships domain (4.29) followed by the psychological (4.09) and environmental (3.88) domains. The lowest score observed was for the physical domain (3.48). With these findings we can say that social and psychological parameters are driving factors of the quality of life in post-mastectomy women. Therefore, these results are useful to establish strategies to improve the quality of life of breast cancer mastectomy patients.

  17. Quality of Life of Post-Mastectomy Women Living in a Semi-Arid Region of Brazil (United States)

    Araújo Neto, Emídio A.; Alves, Beatriz C. A.; Gehrke, Flávia de S.; Azzalis, Ligia A.; Junqueira, Virginia C. B.; Sousa, Luiz Vinicius de A.; Adami, Fernando; Fonseca, Fernando L. A.


    Health is the major reference regarding quality of life; when it comes to breast cancer in particular, the loss of a breast traumatically affects a woman’s life, reflecting on her quality of life. Recognizing this problem, our aim was to investigate the quality of life of women who live in a semi-arid region of Brazil after breast cancer mastectomy. In this exploratory, transversal and observational study, a Brazilian variantof the shorter version of the original instrument from the World Health Organization Quality of Life (WHOQOL-BREF), applied in the study population, was analyzed and their socio-demographic profile was obtained. The sample was composed of 50 mastectomized women. The 50 included patients comprised women at a mean age of 54 years. Most of them had finished elementary school, and their average income was one Brazilian minimum monthly wage. Regarding the data related to quality of life, the highest score was found in the social relationships domain (4.29) followed by the psychological (4.09) and environmental (3.88) domains. The lowest score observed was for the physical domain (3.48). With these findings we can say that social and psychological parameters are driving factors of the quality of life in post-mastectomy women. Therefore, these results are useful to establish strategies to improve the quality of life of breast cancer mastectomy patients. PMID:28587244

  18. Identification of suitabel sites for rainwater harvesting structures in arid and semi-arid regions: A review

    NARCIS (Netherlands)

    Ali, A.A.; Riksen, M.J.P.M.; Ouessar, M.; Ritsema, C.J.


    Harvested rainwater is an alternative source of water in arid and semi-arid regions (ASARs) around the world. Many researchers have developed and applied various methodologies and criteria to identify suitable sites and techniques for rainwater harvesting (RWH). Determining the best method or

  19. Declining agricultural production in rapidly urbanizing semi-arid regions: policy tradeoffs and sustainability indicators (United States)

    Dozier, André Q.; Arabi, Mazdak; Wostoupal, Benjamin C.; Goemans, Christopher G.; Zhang, Yao; Paustian, Keith


    In rapidly urbanizing semi-arid regions, increasing amounts of historically irrigated cropland lies permanently fallowed due to water court policies as agricultural water rights are voluntarily being sold to growing cities. This study develops an integrative framework for assessing the effects of population growth and land use change on agricultural production and evaluating viability of alternative management strategies, including alternative agricultural transfer methods, regional water ownership restrictions, and urban conservation. A partial equilibrium model of a spatially-diverse regional water rights market is built in application of the framework to an exemplary basin. The model represents agricultural producers as profit-maximizing suppliers and municipalities as cost-minimizing consumers of water rights. Results indicate that selling an agricultural water right today is worth up to two times more than 40 years of continued production. All alternative policies that sustain agricultural cropland and crop production decrease total agricultural profitability by diminishing water rights sales revenue, but in doing so, they also decrease municipal water acquisition costs. Defining good indicators and incorporating adequate spatial and temporal detail are critical to properly analyzing policy impacts. To best improve agricultural profit from production and sale of crops, short-term solutions include alternative agricultural transfer methods while long-term solutions incorporate urban conservation.

  20. Characterization of the potential sites in the Brazilian semi-arid region for implantation of helium thermal pilot system of electric power generation; Caracterizacao dos sitios potenciais na regiao do semi-arido brasileiro para implantacao de sistema piloto heliotermico de geracao eletrica

    Energy Technology Data Exchange (ETDEWEB)

    Guimaraes, Ana Paula Cardoso; Nascimento, Marcos Vinicius Gusmao; Menezes, Paulo Cesar Pires; Cheroto, Silvia [Centro de Pesquisas de Energia Eletrica (CEPEL), Rio de Janeiro, RJ (Brazil)]. E-mails:;


    This work contains studies an analyses related to the characterization of the potential sites for application of helium thermal technology at the brazilian semi-arid, with the mapping of the solar resource from the estimative of direct solar radiation data, the mapping of the hydraulic resources indicating the importance of the Sao Francisco basin in the study context, the mapping of the local electric power network, and a survey of the environmental impacts attributed to power plants with solar concentrators. The general objective is to identify the more adequate sites in Brazil for the implantation of a helium thermal pilot system for electric power generation.

  1. Genetic resistance to natural coccidiosis infection in goats in a semi-arid region of India

    Directory of Open Access Journals (Sweden)

    P.K. Rout


    Full Text Available Coccidiosis is one of the major causes of kid mortality in tropical regions and causes significant loss to farmers by affecting growth and feed efficiency in the growing kid. The strategy to control the coccidiosis is mainly through drug usage and is not efficacious at present. Therefore, an alternative strategy is required to control the disease in goats. Increasing genetic resistance to coccidiosis may be an appropriate complementary control strategy. The purpose of this study was to analyse the genetic variation in severity of natural coccidiosis infections in kids in the semi-arid region. The observations were recorded in 227 kids of Barbari and Jamunapari goats. Barbari goats had higher mean faecal oocyst counts (FOC than Jamunapari goats at 3 and 6 months of age. The heritability for FOC was 0.05 and 0.15 at 3 and 6 months of age, respectively. All phenotypic and environmental correlations between FOC and live weight traits were low and negative, indicating a tendency for more heavily infected kids in the flock to grow more slowly. Genetic correlations were largely similar, but had large standard errors. The results suggest that genetic resistance control strategy can potentially be useful for the better performance in the existing managemental condition.

  2. Adaptation of spineless cactus to semi-arid region of Paraíba state, Brazil.

    Directory of Open Access Journals (Sweden)

    Aldo Torres-Sales


    Full Text Available The aim of this study was to evaluate the adaptation of two spineless cactus of the species Nopalea cochenillifera Salm Dyck (Miuda and Alagoas under the environmental conditions of the semi-arid region in the tate of Paraiba, Brazil. An experimental randomized block design with five replications was used. The experiment was conducted under field conditions in São João do Cariri county, State of Paraiba, Brazil (7°22’45,1”S and 36°31’47,2”W, from August 2004 to May 2007. Every twenty-eight days the relative growth rate of cladodes height, length, width, and thickness were evaluated, as well as the number of cladodes per plant and the photosynthetic active area of cladodes and plant. The biomass accumulation per hectare was also measured at the end of the experimental period. One thousand days after planting, the cultivars did not differ in length and width of cladodes. The Alagoas cultivar showed greater thickness of cladode than the Miuda. The Miuda had a larger number of cladodes (p>0.05. There was no difference (p>0.05 in biomass accumulation between cultivars. In conclusion, both cultivars showed similar behavior in the environmental conditions of the semiarid region of the State of Paraiba, Brazil.

  3. Predictability and prediction of summer rainfall in the arid and semi-arid regions of China (United States)

    Xing, Wen; Wang, Bin


    Northwest China (NWC) is an arid and semi-arid region where climate variability and environmental changes are sensitive to precipitation. The present study explores sources and limits of predictability of summer precipitation over NWC using the predictable mode analysis (PMA) of percentage of rainfall anomaly data. Two major modes of NWC summer rainfall variability are identified which are tied to Eurasian continental scale precipitation variations. The first mode features wet northern China corresponding to dry central Siberia and wet Mongolia, which is mainly driven by tropical Pacific sea surface temperature anomalies (SSTA). The second mode features wet western China reflecting wet Central Asia and dry Ural-western Siberia, which strongly links to Indian Ocean SSTA. Anomalous land warming over Eurasia also provides important precursors for the two modes. The cross-validated hindcast results demonstrate these modes can be predicted with significant correlation skills, suggesting that they may be considered as predictable modes. The domain averaged temporal correlation coefficient (TCC) skill during 1979 to 2015 using 0-month (1-month) lead models is 0.39 (0.35), which is considerably higher than dynamical models' multi-model ensemble mean skill (-0.02). Maximum potential attainable prediction skills are also estimated and discussed. The result illustrates advantage of PMA in predicting rainfall over dry land areas and large room for dynamical model improvement. However, secular changes of predictors need to be detected continuously in order to make practical useful prediction.

  4. Predictability and Prediction of Summer Rainfall in the Arid/Semi-arid Regions of China (United States)

    Wang, B.; Xing, W.


    Northwest China (NWC) is an arid and semi-arid region where climate variability and environmental changes are sensitive to precipitation. The present study explores sources and limits of predictability of summer precipitation over NWC using the predictable mode analysis (PMA) of percentage of rainfall anomaly data. Two major modes of NWC summer rainfall variability are identified which are tied to Eurasian continental scale precipitation variations. The first mode features wet northern China corresponding to dry central Siberia and wet Mongolia, which is mainly driven by tropical Pacific sea surface temperature anomalies (SSTA). The second mode features wet western China reflecting wet Central Asia and dry Ural-western Siberia, which strongly links to Indian Ocean SSTA. Anomalous land warming over Eurasia also provides important precursors for the two modes. The cross-validated hindcast results demonstrate these modes can be predicted with significant correlation skills, suggesting that they may be considered as predictable modes. The domain averaged temporal correlation coefficient (TCC) skill during 1979 to 2015 using 0-month (1-month) lead models is 0.39 (0.35), which is considerably higher than dynamical models' multi-model ensemble mean skill (-0.02). Maximum potential attainable prediction skills is also estimated and discussed. The result illustrates advantage of PMA in predicting rainfall over dry land areas and large room for dynamical model improvement. However, secular changes of predictors need to be detected continuously in order to make practical useful prediction.

  5. Allocation of Water Resources in Semi-Arid Region of Northern ...

    African Journals Online (AJOL)

    Thus, the best practice globally is to make optimal use of the little but precarious amount of water found in these areas. This study is aimed at achieving optimal water resources allocation in the semi-arid areas using Dadin-Nkowa dam in Gombe State as a case study. A dynamic model was developed based on observed ...

  6. Hydrological differentiation and spatial distribution of high altitude wetlands in a semi-arid Andean region derived from satellite data


    Otto, M.; Scherer, D; Richters, J.


    High Altitude Wetlands of the Andes (HAWA) belong to a unique type of wetland within the semi-arid high Andean region. Knowledge about HAWA has been derived mainly from studies at single sites within different parts of the Andes at only small time scales. On the one hand, HAWA depend on water provided by glacier streams, snow melt or precipitation. On the other hand, they are suspected to influence hydrology through water retention and veg...

  7. Effects Of Urbanization On Interconnected Water Cycle, Microclimate And Energy Usage In Semi-Arid Regions (United States)

    Jeyachandran, I.; Burian, S. J.; Pardyjak, E.


    Landscape changes induced by urbanization have been found to influence urban water cycle components including evapotranspiration (ET), runoff and water use. For instance, residential areas in semi-arid regions with vegetation subjected to lawn watering have higher ET rates when compared to the other areas in an urban environment. This increase associated with lawn irrigation can contribute to water scarcity problems. Conversely, development of more built surfaces with reduced vegetation leads to increased temperatures and Urban Heat Islands. This increase in temperature, can lead to an increase in energy usage. In order, to quantify the relationship of interconnected landscape, water cycle, microclimate and energy usage there is a need for a modeling system to represent landscape and surface characteristics specific to location and time. A methodology capable of modeling the interconnected urban scenario via a three-step process is presented in this paper. To account for the variability of urban form, the roughness length variation should be represented. An approach to estimate roughness length from Synthetic Aperture Radar (SAR) data has been introduced and the results are included in this paper. The effect of varying urban form and lawn irrigation practices on latent and sensible heat fluxes is represented and modeled by the Urban Heat Flux Model introduced in this paper. The Urban Heat Flux (UHFL) model has the capability to model the sensible and latent heat fluxes spatially and temporally by being able to represent varying conditions of roughness length, surface resistance and lawn irrigation patterns (soil moisture). The UHFL model has an advantage over the existing models by being driven by easily acquirable meteorological data and remote sensing data (which are available for all regions). The overall modeling framework consists of three sub-models: UHFL, the urban climate model (to simulate urban microclimate) and the energy and water usage simulation

  8. Holocene semi-arid oak woodlands in the Irano-Anatolian region of Southwest Asia: natural or anthropogenic? (United States)

    Asouti, Eleni; Kabukcu, Ceren


    It is commonly accepted that, following the end of the Pleistocene, semi-arid deciduous oak woodlands did not spread in the Irano-Anatolian region of Southwest Asia as quickly as they did in the Levantine Mediterranean littoral, despite the fact that climatic improvement occurred broadly at the same time in both regions. Prehistoric impacts on woodland vegetation (such as woodcutting, burning and clearance for cultivation), the harsh continental climate of inland Southwest Asia and its distance from late Pleistocene arboreal refugia have all been discussed in the literature as likely causes of the delay. In this paper we argue that semi-arid deciduous oak woodlands should not be viewed as part of the “natural” vegetation of the Irano-Anatolian region that has been progressively destroyed by millennia of human activities since the Neolithic. They represent instead one of the earliest anthropogenic vegetation types in Southwest Asia, one that owes its very existence to prehistoric landscape practices other scholars commonly label as “destructive”. Drawing on anthracological, pollen and modern vegetation data from central Anatolia we describe how the post-Pleistocene species-rich and structurally diverse temperate semi-arid savanna grasslands were gradually substituted by low-diversity, even-aged Quercus-dominated parklands and wood pastures in the course of the early Holocene. Economic strategies that encouraged the establishment and spread of deciduous oaks included sheep herding that impacted on grass and forb vegetation, the controlling of competing arboreal vegetation through woodcutting, and woodland management practices such as coppicing, pollarding and shredding that enhanced Quercus vegetative propagation, crown and stem growth. Understanding the origin and evolution of the Irano-Anatolian semi-arid oak woodlands of Southwest Asia is of critical importance for reconstructing the changing ecologies and geographical distributions of the progenitors of

  9. Towards a physically-based multi-scale ecohydrological simulator for semi-arid regions (United States)

    Caviedes-Voullième, Daniel; Josefik, Zoltan; Hinz, Christoph


    The use of numerical models as tools for describing and understanding complex ecohydrological systems has enabled to test hypothesis and propose fundamental, process-based explanations of the system system behaviour as a whole as well as its internal dynamics. Reaction-diffusion equations have been used to describe and generate organized pattern such as bands, spots, and labyrinths using simple feedback mechanisms and boundary conditions. Alternatively, pattern-matching cellular automaton models have been used to generate vegetation self-organization in arid and semi-arid regions also using simple description of surface hydrological processes. A key question is: How much physical realism is needed in order to adequately capture the pattern formation processes in semi-arid regions while reliably representing the water balance dynamics at the relevant time scales? In fact, redistribution of water by surface runoff at the hillslope scale occurs at temporal resolution of minutes while the vegetation development requires much lower temporal resolution and longer times spans. This generates a fundamental spatio-temporal multi-scale problem to be solved, for which high resolution rainfall and surface topography are required. Accordingly, the objective of this contribution is to provide proof-of-concept that governing processes can be described numerically at those multiple scales. The requirements for a simulating ecohydrological processes and pattern formation with increased physical realism are, amongst others: i. high resolution rainfall that adequately captures the triggers of growth as vegetation dynamics of arid regions respond as pulsed systems. ii. complex, natural topography in order to accurately model drainage patterns, as surface water redistribution is highly sensitive to topographic features. iii. microtopography and hydraulic roughness, as small scale variations do impact on large scale hillslope behaviour iv. moisture dependent infiltration as temporal

  10. Controlling stomatal aperture in semi-arid regions-The dilemma of saving water or being cool? (United States)

    Chaves, M M; Costa, J M; Zarrouk, O; Pinheiro, C; Lopes, C M; Pereira, J S


    Stomatal regulation of leaf gas exchange with the atmosphere is a key process in plant adaptation to the environment, particularly in semi-arid regions with high atmospheric evaporative demand. Development of stomata, integrating internal signaling and environmental cues sets the limit for maximum diffusive capacity of stomata, through size and density and is under a complex genetic control, thus providing multiple levels of regulation. Operational stomatal conductance to water vapor and CO2 results from feed-back and/or feed-forward mechanisms and is the end-result of a plethora of signals originated in leaves and/or in roots at each moment. CO2 assimilation versus water vapor loss, proposed to be the subject of optimal regulation, is species dependent and defines the water use efficiency (WUE). WUE has been a topic of intense research involving areas from genetics to physiology. In crop plants, especially in semi-arid regions, the question that arises is how the compromise of reducing transpiration to save water will impact on plant performance through leaf temperature. Indeed, plant transpiration by providing evaporative cooling, is a major component of the leaf energy balance. In this paper we discuss the dilemma of 'saving water or being cool' bringing about recent findings from molecular genetics, to development and physiology of stomata. The question of 'how relevant is screening for high/low WUE in crops for semi-arid regions, where drought and heat co-occur' is discussed. Copyright © 2016. Published by Elsevier Ireland Ltd.

  11. Estimating Daily Reference Evapotranspiration in a Semi-Arid Region Using Remote Sensing Data

    Directory of Open Access Journals (Sweden)

    Peshawa M. Najmaddin


    Full Text Available Estimating daily evapotranspiration is challenging when ground observation data are not available or scarce. Remote sensing can be used to estimate the meteorological data necessary for calculating reference evapotranspiration ETₒ. Here, we assessed the accuracy of daily ETₒ estimates derived from remote sensing (ETₒ-RS compared with those derived from four ground-based stations (ETₒ-G in Kurdistan (Iraq over the period 2010–2014. Near surface air temperature, relative humidity and cloud cover fraction were derived from the Atmospheric Infrared Sounder/Advanced Microwave Sounding Unit (AIRS/AMSU, and wind speed at 10 m height from MERRA (Modern-Era Retrospective Analysis for Research and Application. Four methods were used to estimate ETₒ: Hargreaves–Samani (HS, Jensen–Haise (JH, McGuinness–Bordne (MB and the FAO Penman Monteith equation (PM. ETₒ-G (PM was adopted as the main benchmark. HS underestimated ETₒ by 2%–3% (R2 = 0.86 to 0.90; RMSE = 0.95 to 1.2 mm day−1 at different stations. JH and MB overestimated ETₒ by 8% to 40% (R2= 0.85 to 0.92; RMSE from 1.18 to 2.18 mm day−1. The annual average values of ETₒ estimated using RS data and ground-based data were similar to one another reflecting low bias in daily estimates. They ranged between 1153 and 1893 mm year−1 for ETₒ-G and between 1176 and 1859 mm year−1 for ETₒ-RS for the different stations. Our results suggest that ETₒ-RS (HS can yield accurate and unbiased ETₒ estimates for semi-arid regions which can be usefully employed in water resources management.

  12. Groundwater recharge estimation in semi-arid zone: a study case from the region of Djelfa (Algeria) (United States)

    Ali Rahmani, S. E.; Chibane, Brahim; Boucefiène, Abdelkader


    Deficiency of surface water resources in semi-arid area makes the groundwater the most preferred resource to assure population increased needs. In this research we are going to quantify the rate of groundwater recharge using new hybrid model tack in interest the annual rainfall and the average annual temperature and the geological characteristics of the area. This hybrid model was tested and calibrated using a chemical tracer method called Chloride mass balance method (CMB). This hybrid model is a combination between general hydrogeological model and a hydrological model. We have tested this model in an aquifer complex in the region of Djelfa (Algeria). Performance of this model was verified by five criteria [Nash, mean absolute error (MAE), Root mean square error (RMSE), the coefficient of determination and the arithmetic mean error (AME)]. These new approximations facilitate the groundwater management in semi-arid areas; this model is a perfection and amelioration of the model developed by Chibane et al. This model gives a very interesting result, with low uncertainty. A new recharge class diagram was established by our model to get rapidly and quickly the groundwater recharge value for any area in semi-arid region, using temperature and rainfall.

  13. The semi-Arid integrated model (SIM), a regional integrated model assessing water availability, vulnerability, of ecossytems and society in NE-Brazil

    NARCIS (Netherlands)

    Krol, Martinus S.; Jaeger, A.; Bronstert, A.; Krywkow, Jorg


    Northeastern Brazil, an example of vulnerable semi-arid regions on the earth, is characterised by water scarcity and vulnerability of natural resources, pronounced climatic variability and social stress situations. Integrated studies involving hydrology, ecology, meteorology, climatology, pedology,


    Directory of Open Access Journals (Sweden)



    Full Text Available The feeding programs for naked neck chickens in semi-intensive production system from brazilian equatorial semi-arid environment, must consider regional food availability and respective nutritional values. Thus, to evaluate the digestibility and metabolizable energy of alternative forages, it was used 240 naked neck pullets (Isa Label lineage receiving water and ration ad libitum, pair-housed in cages for total collection of excreta on conventional warehouse. It was used a completely randomized design with factorial arrangement (5x2: one control ration (corn and soy meal and other four experimental rations with silk flower hay (Calotropis procera, cassava leafs hay (Manihot esculenta, kills pasture hay (Senna obtusifolia or leucaena leafs hay (Leucaena leucocephala, and all rations were balanced for two growing phases, between 8 and 10 weeks (young pullets and between 14 and 16 weeks of age (old pullets. The values of apparent digestibility of nutrients for all experimental rations were lower than control ration (P <0.05 and it was observed general means of 72.18% for dry matter, 78.12% for crude protein, 66.90% for ether extract, 28.08% for neutral detergent fiber, 18.51% for the acid detergent fiber, 71.64% for gross energy and availability of 15.61% for mineral matter. The general mean of apparent and corrected metabolizable energy of alternative forages was 1217 kcal/ kg and 1108 kcal/kg, respectively, and the higher value was determined for leucaena hay and the lower value for silk flower hay (P <0.05.

  15. Disponibilidade familiar de alimentos na Zona da Mata e Semi-Árido do Nordeste do Brasil Household food availability in the Forest Zone (Zona da Mata and Semi-Arid Brazilian Northeast regions

    Directory of Open Access Journals (Sweden)

    Mônica Maria Osório


    Full Text Available OBJETIVO: Este trabalho teve como objetivo caracterizar a disponibilidade de alimentos em domicílios de Gameleira (PE e São João do Tigre (PB, municípios das referidas regiões, considerando a freqüência dos alimentos, o número de pessoas no domicílio e a escolaridade do chefe da família. MÉTODOS: A amostra foi constituída de 502 e 458 famílias, em Gameleira (PE e São João do Tigre (PB, respectivamente, de área urbana e rural de cada município. As informações, referentes aos sete dias anteriores à entrevista, foram fornecidas pelo responsável pela preparação dos alimentos. RESULTADOS: Verifica-se a disponibilidade de 33 alimentos em Gameleira (PE e 30 em São João do Tigre (PB, em mais de 20% das famílias; restringindo-se a 16 e 15 alimentos nos dois municípios respectivamente, quando considerada a disponibilidade em 50% das famílias. Os alimentos disponíveis na maioria dos domicílios possuíam alto valor energético e pertenciam aos grupos de cereais e leguminosas, em detrimento de hortaliças, frutas e produtos de origem animal. A disponibilidade alimentar sofreu pouca variação em decorrência do número de pessoas no domicílio e da escolaridade do chefe da família. CONCLUSÃO: O estímulo ao aumento qualitativo e quantitativo da disponibilidade familiar de alimentos deve ser o foco dos esforços governamentais em programas sociais de combate à fome.OBJECTIVE: The purpose of this study was to determine household food availability in Gameleira (PE and São João do Tigre (PB, municipalities in the abovementioned regions, taking into account the frequency of food consumption, number of people per household, and education level of the head of the household. METHODS: The sample consisted of 502 and 458 families in Gameleira (PE and São João do Tigre (PB, respectively, living in both urban and rural areas. Information on food consumption during the seven days prior to the interview was provided by the person in

  16. New Approaches for Responsible Management of Offshore Springs in Semi-arid Regions (United States)

    Shaban, Amin; de Jong, Carmen; Al-Sulaimani, Zaher


    In arid and semi-arid regions, such as the Mediterranean and Gulf Region where water is scarce water demand has been exacerbated and become a major environmental challenge. Presently there is massive pressure to develop new water sources to alleviate existing water stress. In the quest for more freshwater even groundwater discharge into the sea in the form of "off-shore freshwater springs" (or submarine groundwater discharge) has been contemplated as a potential source of unconventional water in coastal zones. Offshore-springs are derived from aquifers with complex geological controls mainly in the form of faults and karst conduits. Representing a border-line discipline, they have been poorly studied with only few submarine groundwater monitoring sites existing worldwide. Recently, innovative techniques have been developed enabling springs to be detected via remote sensing such as airborne surveys or satellite images. "Thermal Anomalies" can be clearly identified as evidence for groundwater discharge into the marine environment. A diversity of groundwater routes along which off-shore springs are fed from land sources can be recognized and near-shore and offshore springs differentiated and classified according to their geometry. This is well pronounced along the coast of Lebanon and offshore of Oman. Offshore springs play an important role in the marine ecosystem as natural sources of mercury, metals, nutrients, dissolved carbon species and in cooling or warming ocean water. However, they are extremely sensitive to variations in qualitative and quantitative water inputs triggered by climate change and anthropogenic impacts especially in their recharge zones. Pollutants such as sewage, detergents, heavy metals or herbicides that negatively affect water quality of offshore springs can transit the groundwater rapidly. Recently these springs have also been severely affected by uncontrolled water abstraction from land aquifers. In Bahrain, overpumping combined with

  17. Observations of trace gases, photolysis rate coefficients and model simulations over semi-arid region, India (United States)

    Lingaswamy, A. P.; Arafath, S. Md; Balakrishnaiah, G.; Rama Gopal, K.; Siva Kumar Reddy, N.; Raja Obul Reddy, K.; Reddy, R. R.; Chakradhar Rao, T.


    Continuous ground-based measurements of CO, SO2 and NO2 were carried out in a semi-arid rural area, Anantapur [14.62 0N, 77.65 0E], Southern India, for the period January 2012-December 2012. The maximum CO concentration was observed in winter (310 ± 17 ppbv) followed by summer (180 ± 21 ppbv) and post monsoon (174 ± 20 ppbv), while the minimum in monsoon (72 ± 9 ppbv). Seasonal mean NO2/NOx ratios for monsoon, post monsoon, winter and summer were about 0.88, 0.91, 0.76 and 0.80 respectively, indicating a higher conversion of NO to NO2 over the measurement site. Monthly mean low SO2 mixing ratio was found (0.46 ± 0.02 ppbv) in monsoon and high (2.42 ± 0.21 ppbv) in winter. Keeping the emissions aside, the levels of CO, SO2 and NO2 were influenced by meteorology, urban effects and trans-boundary transport in the lower troposphere. Atmospheric boundary layer (ABL) had the good correlation coefficient (R = 0.76) with solar radiation during daytime, while it was mainly correlated with wind speed during night time (R = 0.42). Diurnal trend of atmospheric visibility was found to be maximum during noon times at around (14:00-16:00 h) about 76 k.m. and minimum during morning periods (06:00-08:00 h) about 45 k.m. A strong positive correlation was observed between BC and CO (R = 0.71) with an average slope, suggesting common or proximate sources likely to be traffic emissions contribution for the production of BC and CO. The SO2/NOx and CO/NOx study were strongly suggested that mobile sources were larger contributors over the site and the evidence of transport of emissions from other surrounding regions. Tropospheric Ultraviolet Visible (TUV) radiative transfer model was used to calculate the Photolysis rate coefficients (J(O3), J(NO2)). Chemical box model (NCAR-MM) was used to simulate diurnal variation of CO and the results were reported.

  18. Dynamics of soil carbon and nitrogen stocks after afforestation in arid and semi-arid regions: A meta-analysis. (United States)

    Liu, Xiang; Yang, Tao; Wang, Quan; Huang, Farong; Li, Lanhai


    Arid and semi-arid regions store approximately 27% of global soil organic carbon (SOC), thus playing an important role in the global carbon cycle. Although afforestation is widely used to achieve the goals of landscape protection and ecological restoration in these regions, its effects on the dynamics of SOC and total nitrogen (TN) stocks as well as the related controlling factors are still poorly understood. In this study, a meta-analysis was conducted by compiling results from published studies to evaluate the influences of afforestation on dynamics of SOC and TN stocks in mineral soils (0-30cm) in arid and semi-arid regions, and to examine whether the changes in SOC and TN stocks were influenced by prior land-use, planted tree species and plantation age. The results showed that overall, afforestation significantly increased SOC stock by 131% and TN stock by 88%. Prior land-use was found to be the most important factor that influenced the dynamics of SOC and TN stocks following afforestation. Significantly larger increases in SOC and TN stocks were observed after barren land afforestation in comparison to cropland and grassland afforestation. The accumulations in SOC and TN stocks after afforestation decreased in the following order: broadleaf deciduous forests>coniferous forests>broadleaf evergreen forests. However, significant differences in SOC and TN accumulations were only detected between broadleaf deciduous forests and broadleaf evergreen forests. Plantation age did not affect the dynamics of SOC and TN stocks after afforestation, mainly due to the rapid accumulations in SOC and TN after barren land afforestation. The results indicate that afforestation, especially on barren land with broadleaf deciduous species, provides substantial opportunities for SOC and TN sequestrations in arid and semi-arid regions. Copyright © 2017 Elsevier B.V. All rights reserved.

  19. A pollution fate and transport model application in a semi-arid region: Is some number better than no number? (United States)

    Özcan, Zeynep; Başkan, Oğuz; Düzgün, H Şebnem; Kentel, Elçin; Alp, Emre


    Fate and transport models are powerful tools that aid authorities in making unbiased decisions for developing sustainable management strategies. Application of pollution fate and transport models in semi-arid regions has been challenging because of unique hydrological characteristics and limited data availability. Significant temporal and spatial variability in rainfall events, complex interactions between soil, vegetation and topography, and limited water quality and hydrological data due to insufficient monitoring network make it a difficult task to develop reliable models in semi-arid regions. The performances of these models govern the final use of the outcomes such as policy implementation, screening, economical analysis, etc. In this study, a deterministic distributed fate and transport model, SWAT, is applied in Lake Mogan Watershed, a semi-arid region dominated by dry agricultural practices, to estimate nutrient loads and to develop the water budget of the watershed. To minimize the discrepancy due to limited availability of historical water quality data extensive efforts were placed in collecting site-specific data for model inputs such as soil properties, agricultural practice information and land use. Moreover, calibration parameter ranges suggested in the literature are utilized during calibration in order to obtain more realistic representation of Lake Mogan Watershed in the model. Model performance is evaluated using comparisons of the measured data with 95%CI for the simulated data and comparison of unit pollution load estimations with those provided in the literature for similar catchments, in addition to commonly used evaluation criteria such as Nash-Sutcliffe simulation efficiency, coefficient of determination and percent bias. These evaluations demonstrated that even though the model prediction power is not high according to the commonly used model performance criteria, the calibrated model may provide useful information in the comparison of the

  20. Modeling the Surface Water-Groundwater Interaction in Arid and Semi-Arid Regions Impacted by Agricultural Activities (United States)

    Tian, Y.; Wu, B.; Zheng, Y.


    In many semi-arid and arid regions, interaction between surface water and groundwater plays an important role in the eco-hydrological system. The interaction is often complicated by agricultural activities such as surface water diversion, groundwater pumping, and irrigation. In existing surface water-groundwater integrated models, simulation of the interaction is often simplified, which could introduce significant simulation uncertainty under certain circumstance. In this study, GSFLOW, a USGS model coupling PRMS and MODFLOW, was improved to better characterize the surface water-groundwater interaction. The practices of water diversion from rivers, groundwater pumping and irrigation are explicitly simulated. In addition, the original kinematic wave routing method was replaced by a dynamic wave routing method. The improved model was then applied in Zhangye Basin (the midstream part of Heihe River Baisn), China, where the famous 'Silk Road' came through. It is a typical semi-arid region of the western China, with extensive agriculture in its oasis. The model was established and calibrated using the data in 2000-2008. A series of numerical experiments were conducted to evaluate the effect of those improvements. It has been demonstrated that with the improvements, the observed streamflow and groundwater level were better reproduced by the model. The improvements have a significant impact on the simulation of multiple fluxes associated with the interaction, such as groundwater discharge, riverbed seepage, infiltration, etc. Human activities were proved to be key elements of the water cycle in the study area. The study results have important implications to the water resources modeling and management in semi-arid and arid basins.

  1. Immunomodulatory activity of extracts from Cordia superba Cham. and Cordia rufescens A. DC. (Boraginaceae, plant species native from Brazilian Semi-arid

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    José Fernando Oliveira Costa

    Full Text Available The family Boraginaceae is widely distributed in Brazil and in the Northeastern region some species are popularly used to treat symptoms of rheumatism, painful menstruation and dyspepsia. In this work we studied Cordia superba Cham. and C. rufescens A. DC., native from Brazilian Semi-arid region, in order to investigate their immunomodulatory activity. Six extracts were prepared from aerial parts of C. superba and C. rufescens. The cytotoxicity was evaluated using splenocytes from BALB/c mice. The immunomodulatory activity was determined by in vitro assays using activated mouse macrophages and lymphocytes. Peritoneal macrophages obtained from BALB/c mice were stimulated with IFN-gamma and LPS in the presence/absence of the samples. The NO production was measured indirectly through Griess method. Three samples inhibited the production of nitric oxide in values near 50% at a concentration of 100 µg/mL. To evaluate the effects of the extracts on lymphocytes, splenocytes from BALB/c mice were incubated with the samples and concanavalin A. Proliferation inhibition was determined by analysis of ³H-thymidine uptake. Samples from the two species had a strong inhibitory activity on lymphocyte proliferation and IL-2 production. Two chloroform extracts prepared from aerial parts of C. rufescens had the lowest IC50 values (7.6 and 11.0 µg/mL.

  2. Direct radiative forcing properties of atmospheric aerosols over semi-arid region, Anantapur in India

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    Kalluri, Raja Obul Reddy; Gugamsetty, Balakrishnaiah [Aerosol & Atmospheric Research Laboratory, Department of Physics, Sri Krishnadevaraya University, Anantapur 515 003, Andhra Pradesh (India); Kotalo, Rama Gopal, E-mail: [Aerosol & Atmospheric Research Laboratory, Department of Physics, Sri Krishnadevaraya University, Anantapur 515 003, Andhra Pradesh (India); Nagireddy, Siva Kumar Reddy; Tandule, Chakradhar Rao; Thotli, Lokeswara Reddy [Aerosol & Atmospheric Research Laboratory, Department of Physics, Sri Krishnadevaraya University, Anantapur 515 003, Andhra Pradesh (India); Rajuru Ramakrishna, Reddy [Aerosol & Atmospheric Research Laboratory, Department of Physics, Sri Krishnadevaraya University, Anantapur 515 003, Andhra Pradesh (India); Srinivasa Ramanujan Institute of Technology, B.K. Samudram Mandal, Anantapur 515 701, Andhra Pradesh (India); Surendranair, Suresh Babu [Space Physics Laboratory, Vikram Sarabhai Space Centre, Trivandrum 695 022, Kerala (India)


    This paper describes the aerosols optical, physical characteristics and the aerosol radiative forcing pertaining to semi-arid region, Anantapur for the period January 2013-December 2014. Collocated measurements of Aerosol Optical Depth (AOD) and Black Carbon mass concentration (BC) are carried out by using MICROTOPS II and Aethalometer and estimated the aerosol radiative forcing over this location. The mean values of AOD at 500 nm are found to be 0.47 ± 0.09, 0.34 ± 0.08, 0.29 ± 0.06 and 0.30 ± 0.07 during summer, winter, monsoon and post-monsoon respectively. The Angstrom exponent (α{sub 380–1020}) value is observed maximum in March (1.25 ± 0.19) and which indicates the predominance of fine - mode aerosols and lowest in the month of July (0.33 ± 0.14) and may be due to the dominance of coarse-mode aerosols. The diurnal variation of BC is exhibited two height peaks during morning 07:00–08:00 (IST) and evening 19:00–21:00 (IST) hours and one minima noticed during afternoon (13:00–16:00). The highest monthly mean BC concentration is observed in the month of January (3.4 ± 1.2 μg m{sup −3}) and the lowest in July (1.1 ± 0.2 μg m{sup −3}). The estimated Aerosol Direct Radiative Forcing (ADRF) in the atmosphere is found to be + 36.8 ± 1.7 W m{sup −2}, + 26.9 ± 0.2 W m{sup −2}, + 18.0 ± 0.6 W m{sup −2} and + 18.5 ± 3.1 W m{sup −2} during summer, winter, monsoon and post-monsoon seasons, respectively. Large difference between TOA and BOA forcing is observed during summer which indicate the large absorption of radiant energy (36.80 W m{sup −2}) which contributes more increase in atmospheric heating by ~ 1 K/day. The BC contribution on an average is found to be 64% and is responsible for aerosol atmospheric heating. - Highlights: • The mean values of AOD{sub 500} are found to be high during summer whereas low in monsoon. • The highest values of BC are observed in January and the lowest in the month of July. • The annual mean

  3. The linkage between household water consumption and rainfall in the semi-arid region of East Nusa Tenggara, Indonesia (United States)

    Messakh, J. J.; Moy, D. L.; Mojo, D.; Maliti, Y.


    Several studies have shown that the amount of water consumption by communities will depend on the factors of water consumption patterns that are influenced by social, cultural, economic and local climate conditions. Research on the linkage between rainfall and household water consumption in semi-arid areas of Indonesia has never been done. This study has been conducted on 17 regions in NTT, and case study has taken samples in one town and one village. The research used survey and documentation method. The results show that the average amount of household water consumption in semi-arid region of East Nusa Tenggara is 107 liters / person / day. Statistical test results using Pearson correlation found r = -0.194 and sig = 0.448. This means that there is a negative correlation between rainfall and household water consumption. The greater the rainfall the smaller the consumption of water, or the smaller the rainfall the greater the consumption of water, but the linkage is not significant. Research shows that the amount of household water consumption will be influenced by many interrelated factors and none of the most dominant factors, including the size of the rainfall that occurs in a region.

  4. Assessing land features in semi-arid regions from multi-temporal SAR data (United States)

    Bianchini, M.; Macelloni, G.; Paloscia, S.; Pampaloni, P.; Santi, E.; Aqid, N.; Ouazar, D.; Zribi, M.


    In this paper an experiment aimed at evaluating the potential of SAR systems in monitoring hydrological parameters in a large watershed of a semi-desert area was described. Remote sensing and ground truth measurements were carried out in Morocco, within the framework of the EC project FLAUBERT (Flood in Arid Units By Earth Remote Techniques). ERS/C-band SAR and JERS/L-band SAR images collected from October 97 to June 99 were analyzed. In spite of the very low changes in space and time, the spatial and temporal analysis of L- and C-band backscattering showed the capability of SAR to point out yearly variations due to vegetation cycle and rain events and to map semi-arid vegetation. By using interferometric coherence a separation of several soil and vegetation classes in the same image was obtained.


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    Rodrigo Ferreira de Sousa


    Full Text Available The aim of this study was to investigate aspects of ethnoecological and ethnobotanical of carnauba wax (Copernicia prunifera (Miller H. E. Moore, Arecaceae in an extractive community of municipality of Ipanguaçu, Rio Grande do Norte state. We interviewed key informants, using the technique of inducing nonspecific, guided tour and direct observation to confirm the data. According to most residents of Pedro Ezequiel Araújo community, the area of carnauba wax in the region is natural. In the research ethnoecological, 73% of informants reported the occurrence of “a different kind of carnauba”, known as “white carnauba” phenotypically distinct from the “common carnauba wax” by presenting clear stipe, smaller fruits and absence of spines on the petiole, and is rare at the study site. Much of the informants observed phenological phases of carnauba wax, being consistent in stating that the species has fruits dispersed by bats. In ethnobotany, powder wax was cited by all as the most important product extracted from leaves of carnauba and the most used, followed by fruit, stem and root. Were still reported the division of work in the extraction of powder wax from the carnauba. The results of this research will contribute to knowledge of ethnobotanical and ethnoecological carnauba, supporting strategies for management and conservation of natural populations.

  6. Amphibian and reptile biodiversity in the semi-arid region of the municipality of Nopala de Villagrán, Hidalgo, Mexico (United States)

    Mendoza-Hernández, Andrés Alberto; Flores-Villela, Oscar


    Current global changes are putting both biodiversity and the processes that depend on it at risk. This is especially true for semi-arid regions and the flagship groups that inhabit them, such as amphibians and reptiles. Semi-arid regions are often thought to have lower biodiversity and thus have been overlooked, resulting in the underestimation of their biological richness. Therefore, the aim of this study was to conduct an inventory of amphibians and reptiles in the semi-arid municipality of Nopala de Villagrán, Mexico, and analyze its biodiversity in relation to the seasons, vegetation and microhabitat. During a year of fieldwork, we found 24 species in the area, most of them of low abundance, and one of which was recorded for the first time for the state of Hidalgo. We documented five amphibian species and 19 reptile species. We also found that observed species richness was higher in the rainy season and in xeric scrub vegetation, although only the season differences were significant according to rarefaction curves. Our findings highlight the importance of seasonality and vegetation type for the species that inhabit this semi-arid region. This study broadens our understanding of the importance of semi-arid regions and, by extension, that of other areas with similar characteristics. PMID:29312825

  7. Hierarchical distance-based fuzzy approach to evaluate urban water supply systems in a semi-arid region. (United States)

    Yekta, Tahereh Sadeghi; Khazaei, Mohammad; Nabizadeh, Ramin; Mahvi, Amir Hossein; Nasseri, Simin; Yari, Ahmad Reza


    Hierarchical distance-based fuzzy multi-criteria group decision making was served as a tool to evaluate the drinking water supply systems of Qom, a semi-arid city located in central part of Iran. A list of aspects consisting of 6 criteria and 35 sub-criteria were evaluated based on a linguistic term set by five decision-makers. Four water supply alternatives including "Public desalinated distribution system", "PET Bottled Drinking Water", "Private desalinated water suppliers" and "Household desalinated water units" were assessed based on criteria and sub-criteria. Data were aggregated and normalized to apply Performance Ratings of Alternatives. Also, the Performance Ratings of Alternatives were aggregated again to achieve the Aggregate Performance Ratings. The weighted distances from ideal solution and anti-ideal solution were calculated after secondary normalization. The proximity of each alternative to the ideal solution was determined as the final step. The alternatives were ranked based on the magnitude of ideal solutions. Results showed that "Public desalinated distribution system" was the most appropriate alternative to supply the drinking needs of Qom population. Also, "PET Bottled Drinking Water" was the second acceptable option. A novel classification of alternatives to satisfy the drinking water requirements was proposed which is applicable for the other cities located in semi-arid regions of Iran. The health issues were considered as independent criterion, distinct from the environmental issues. The constraints of high-tech alternatives were also considered regarding to the level of dependency on overseas.

  8. Food resources used by three species of fish in the semi-arid region of Brazil

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    Márcio J. da Silva


    Full Text Available Temporary and semi-permanent aquatic habitats in semi-arid Brazil have been reported as important sites supporting a diverse fish fauna. As such, they must be able to trophically sustain fish species that feed at different trophic levels. This study aims to describe the diets of Astyanax aff. bimaculatus, Hoplias malabaricus and Prochilodus brevis in aquatic systems in semi-arid Brazil, providing evidence of the importance of these habitats as supporters of large consumers like fish. The diet of the three species studied was diverse, feeding on a range of food items, from microalgae to fish. Despite that, a few items were more important to each of the study species. These results and the relatively high rates of stomach fullness indicate that a diverse and abundant food range is available in the study sites, but species seem to select some food resources. The present study provides evidence that despite being highly variable, intermittent and semi-permanent aquatic systems in semi-arid Brazil are able to trophically sustain large consumers.Os ambientes aquáticos temporários e semi-permanentes do semiárido brasileiro tem sido mostrados como importantes sítios que possuem uma diversa fauna de peixes. Desta forma, esses ambientes devem ser capazes de sustentar, do ponto de vista trófico, populações de peixes que se alimentam em diversos níveis tróficos. O presente estudo tem como objetivo descrever o hábito alimentar de Astyanax aff. bimaculatus, Hoplias malabaricus e Prochilodus brevis em ambientes aquáticos do semiárido brasileiro, fornecendo evidências da importância desses habitats para manutenção da diversidade de consumidores como os peixes. A composição da dieta das espécies estudadas foi diversificada, já que alimentaram-se de uma variedade de classes de itens, desde microalgas até peixes. Apesar disso, alguns itens foram mais importantes para cada uma das três espécies. Estes resultados, e as altas taxas de reple

  9. Mapping Annual Forest Cover in Sub-Humid and Semi-Arid Regions through Analysis of Landsat and PALSAR Imagery

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    Yuanwei Qin


    Full Text Available Accurately mapping the spatial distribution of forests in sub-humid to semi-arid regions over time is important for forest management but a challenging task. Relatively large uncertainties still exist in the spatial distribution of forests and forest changes in the sub-humid and semi-arid regions. Numerous publications have used either optical or synthetic aperture radar (SAR remote sensing imagery, but the resultant forest cover maps often have large errors. In this study, we propose a pixel- and rule-based algorithm to identify and map annual forests from 2007 to 2010 in Oklahoma, USA, a transitional region with various climates and landscapes, using the integration of the L-band Advanced Land Observation Satellite (ALOS PALSAR Fine Beam Dual Polarization (FBD mosaic dataset and Landsat images. The overall accuracy and Kappa coefficient of the PALSAR/Landsat forest map were about 88.2% and 0.75 in 2010, with the user and producer accuracy about 93.4% and 75.7%, based on the 3270 random ground plots collected in 2012 and 2013. Compared with the forest products from Japan Aerospace Exploration Agency (JAXA, National Land Cover Database (NLCD, Oklahoma Ecological Systems Map (OKESM and Oklahoma Forest Resource Assessment (OKFRA, the PALSAR/Landsat forest map showed great improvement. The area of the PALSAR/Landsat forest was about 40,149 km2 in 2010, which was close to the area from OKFRA (40,468 km2, but much larger than those from JAXA (32,403 km2 and NLCD (37,628 km2. We analyzed annual forest cover dynamics, and the results show extensive forest cover loss (2761 km2, 6.9% of the total forest area in 2010 and gain (3630 km2, 9.0% in southeast and central Oklahoma, and the total area of forests increased by 684 km2 from 2007 to 2010. This study clearly demonstrates the potential of data fusion between PALSAR and Landsat images for mapping annual forest cover dynamics in sub-humid to semi-arid regions, and the resultant forest maps would be

  10. Analysis and evaluation of tillage on an alfisol in a semi-arid tropical region of India

    NARCIS (Netherlands)

    Klaij, M.C.


    Tillage field experiments were conducted on Alfisols in a semi-arid tropical environment in India. The research was conducted within the framework of the Farming Systems Research Program of the International Crops Research Institute for the Semi-Arid Tropics (ICRISAT).

    To put the

  11. Monoterpene emissions from Pinus halepensis forests in a semi-arid region (Israel) (United States)

    Seco, R.; Karl, T.; Turnipseed, A. A.; Greenberg, J.; Guenther, A. B.; Llusia, J.; Penuelas, J.; Kim, S.; Dicken, U.; Rotenberg, E.; Rohatyn, S.; Preisler, Y.; Yakir, D.


    Atmospheric volatile organic compounds (VOCs) have key environmental and biological roles, and can affect atmospheric chemisty, secondary aerosol formation, and as a consequence also climate. At the same time, global changes in climate arising from human activities can modify the VOC emissions of vegetation in the coming years. Monoterpene emission fluxes were measured during April 2013 at two forests in the semi-arid climate of Israel. Both forests were dominated by the same pine species, Pinus halepensis, but differed in the amount of annual average precipitation received (280 and 800 mm at Yatir and Birya, respectively). Measurements performed included leaf-level sampling as well as canopy-level flux calculations. Leaf level monoterpene emissions were sampled from leaf cuvettes with adsorbent cartridges and later analyzed by GC-MS. Canopy scale fluxes were calculated with the Disjunct Eddy Covariance technique by means of a Quadrupole PTRMS. We report the differences observed between the two forests in terms of photosynthetic activity and monoterpene emissions, aiming to see the effect of the different precipitation regimes at each location.

  12. Robust environmental flow release strategies in arid and semi-arid regions to rehabilitate endangered saline lakes (United States)

    Fazel, Nasim; Torabi Haghighi, Ali; Kløve, Bjørn


    Saline lakes despite their extreme importance for critical habitat, are often threatened by desiccation due to irrigation and land development. For many closed lakes, the lake's level and salinity is highly controlled by hydrology of the basin and the balance between inflows and evaporation. In arid and semi-arid regions overexploitation of water for agricultural use in upstream has imbalance the natural inflow to the lake and the evaporation from surface. Due to the high irrigation water demand in these regions, environmental flow release has led to greater water withdrawals in irrigation seasons. Considering farmers attitude in irrigation along with hydrological and climatic condition, could be an important criteria to design proper environmental flow release plan to maximise lakes' inflow. This study employs a new methodology to define environmental flow strategy in arid and semi-arid regions with intensive agricultural lands adjacent to a terminal lake. The method analyzes farmers' water-use behaviour and natural flow regime in the upstream to design the environmental flow release strategy from a reservoir. We have applied the methodology to water resources systems in Lake Urmia Basin, a highly endangered saline lake in Iran. The spatial analysis show that the lake basin's hydrology is controlled by many upstream reservoirs and intensive agricultural water demand in downstream. Cropland has increased rapidly in the lake basin during last decades through construction of dams and diversion. The released environmental flow was exploited by farmers in lowlands and inflow to the lake in some rivers has been decreased even by 80%. The new environmental flow release has showed water should be released in the shortest possible time (according to reservoir outlet capacity) during the lowest irrigation demand period.

  13. Spatiotemporal reference evapotranspiration changes in humid and semi-arid regions of Iran: past trends and future projections (United States)

    Nouri, Milad; Homaee, Mehdi; Bannayan, Mohammad


    This study was undertaken to investigate the reference evapotranspiration (ET0) changes in semi-arid and humid regions of Iran during the past (1966-2010) and future (2011-2099). For detecting possible trend in ET0 over 1966-2010, the Mann-Kendall trend test was employed. The outputs of Hadley Centre coupled model version 3 (HadCM3) and the third generation couple global climate model (CGCM3) under A2, B2, and A1B emission scenarios were also used to simulate the future ET0 changes by statistical downscaling model (SDSM). The results indicated upward trends in annual ET0 during 1966-2010 in the most sites. Furthermore, the significant increasing ET0 trends were identified for 54.5, 18.2, 27.3, 22.7, and 36.3% of studied locations during winter, spring, summer, autumn, and entire year, respectively. Positive trends in ET0 were mostly found in northeast, west, and northwest Iran, and insignificant downward ET0 trends were primarily detected in southwestern and southern stations in 1966-2010. The ET0 changes were attributed to wind speed changes in semi-arid regions and mean temperature changes in humid areas in the past period. An increase in ET0 was projected under all scenarios due mainly to temperature rise and declined relative humidity in the investigated regions from 2011 to 2100. Averaged over all stations, the lowest and highest ET0 increment were, respectively, modeled for autumn and summer using CGCM3 outputs and winter and autumn using HadCM3 outputs. Given significant ET0 increase over the twenty-first century, appropriate adaptive measures are required to reduce negative impacts of climate change on water resources and agricultural productions.

  14. Epidemiology and seasonal dynamics of gastrointestinal nematode infections of sheep in a semi-arid region of eastern Ethiopia. (United States)

    Sissay, Menkir M; Uggla, Arvid; Waller, Peter J


    A study on the epidemiology and seasonal dynamics of gastrointestinal nematode infections of sheep was carried out in a semi-arid region of eastern Ethiopia for 2.5 years (May 2003 to September 2005). The experimental flock comprised a total of 60 Black Head Ogaden sheep, consisting of four equal groups of young male and female and old male and female sheep. These grazed on communal pastures together with a larger university flock, as well as with animals owned by neighbouring small-holder farmers. A new experimental flock was established each year of the study. Parasitological data (EPG, faecal culture L3, PCV and FAMACHA estimates) and animal performance (weight change) were recorded each month on all experimental animals. In addition, four tracer lambs were assigned each month to the flock to determine the seasonal patterns of infective larvae acquired from pasture. Results showed distinct seasonal patterns associated with the bi-modal annual rainfall. High levels of infection occurred during the short and long rain seasons with peaks occurring in May and September of each year. Haemonchus contortus was the most prevalent parasite, followed by Trichostrongylus spp., with a number of other nematode species being occasionally recorded. H. contortus showed and increased propensity to undergo arrested development during the dry seasons. Correlations between EPG and PCV, EPG and FAMACHA eye scores, and PCV and FAMACHA eye scores were all highly significant (P<0.001). However, there was no significant association between the EPG and LW of the study animals during each study year. This information will provide a basis for developing epidemiologically based control strategies for gastrointestinal nematode parasites that are appropriate for flocks owned by small-holder farmers of semi-arid areas of eastern Ethiopia.

  15. Linking Bayesian and agent-based models to simulate complex social-ecological systems in semi-arid regions

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    Aloah J Pope


    Full Text Available Interdependencies of ecologic, hydrologic, and social systems challenge traditional approaches to natural resource management in semi-arid regions. As a complex social-ecological system, water demands in the Sonoran Desert from agricultural and urban users often conflicts with water needs for its ecologically-significant riparian corridors. To explore this system, we developed an agent-based model to simulate complex feedbacks between human decisions and environmental conditions in the Rio Sonora Watershed. Cognitive mapping in conjunction with stakeholder participation produced a Bayesian model of conditional probabilities of local human decision-making processes resulting to changes in water demand. Probabilities created in the Bayesian model were incorporated into the agent-based model, so that each agent had a unique probability to make a positive decision based on its perceived environment at each point in time and space. By using a Bayesian approach, uncertainty in the human decision-making process could be incorporated. The spatially-explicit agent-based model simulated changes in depth-to-groundwater by well pumping based on an agent’s water demand. Changes in depth-to-groundwater feedback to influence agent behavior, as well as determine unique vegetation classes within the riparian corridor. Each vegetation class then provides varying stakeholder-defined quality values of ecosystem services. Using this modeling approach allowed us to examine effects on both the ecological and social system of semi-arid riparian corridors under various scenarios. The insight provided by the model contributes to understanding how specific interventions may alter the complex social-ecological system in the future.

  16. Quantifying the impact of groundwater depth on evapotranspiration in a semi-arid grassland region

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    M. E. Soylu


    Full Text Available Interactions between shallow groundwater and land surface processes play an important role in the ecohydrology of riparian zones. Some recent land surface models (LSMs incorporate groundwater-land surface interactions using parameterizations at varying levels of detail. In this paper, we examine the sensitivity of land surface evapotranspiration (ET to water table depth, soil texture, and two commonly used soil hydraulic parameter datasets using four models with varying levels of complexity. The selected models are Hydrus-1D, which solves the pressure-based Richards equation, the Integrated Biosphere Simulator (IBIS, which simulates interactions among multiple soil layers using a (water-content variant of the Richards equation, and two forms of a steady-state capillary flux model coupled with a single-bucket soil moisture model. These models are first evaluated using field observations of climate, soil moisture, and groundwater levels at a semi-arid site in south-central Nebraska, USA. All four models are found to compare reasonably well with observations, particularly when the effects of groundwater are included. We then examine the sensitivity of modelled ET to water table depth for various model formulations, node spacings, and soil textures (using soil hydraulic parameter values from two different sources, namely Rawls and Clapp-Hornberger. The results indicate a strong influence of soil texture and water table depth on groundwater contributions to ET. Furthermore, differences in texture-specific, class-averaged soil parameters obtained from the two literature sources lead to large differences in the simulated depth and thickness of the "critical zone" (i.e., the zone within which variations in water table depth strongly impact surface ET. Depending on the depth-to-groundwater, this can also lead to large discrepancies in simulated ET (in some cases by more than a factor of two. When the Clapp-Hornberger soil parameter dataset is used, the

  17. Impacts of wastewater irrigation in arid and semi arid regions: case of Sidi Abid region, Tunisia (United States)

    Bouri, Salem; Abida, Habib; Khanfir, Hafedh


    Impacts of irrigation with treated wastewater effluents on soils and groundwater aquifer in the vicinity of Sidi Abid Region (Tunisia) are evaluated. The groundwater aquifer was monitored by several piezometers, where monthly water levels were registered and groundwater salinity was evaluated. This resulted in characterizing the spatial and temporal evolution of the hydrochemical and hydrodynamic properties of the aquifer, showing thereby the impact of artificial recharge. Piezometric maps for pre-recharge and post-recharge situations were developed and a comparison study of both piezometric situations was considered. The piezometric evolution map showed a generalized rise of the piezometric level in the vicinity of the irrigation zone. The extent of recharge was shown to increase with time as the groundwater level increase, which was localized in the vicinity of the irrigation area, reached more extended zones. Several groundwater samples were withdrawn from wells and piezometers and analyzed. Examining the corresponding physical and chemical parameters showed an increase in the concentrations of nutrients (28 mg/l for NO3 and 3.97 mg/l for NH4) in the groundwater aquifer below the irrigation zone, which confirms again the infiltration of treated wastewater effluents. The evolution of soil salinity was examined through chemical analysis of soil samples. Electric conductivities of soils were generally shown to be less than 4 mS/cm while the irrigation water has an electric conductivity that may reach 6.63 mS/cm. This might be explained by the phenomenon of dilution and the capacity of soils to evacuate salts downward.

  18. Breeding under unpredictable conditions: Annual variation in gonadal maturation, energetic reserves and plasma levels of androgens and corticosterone in anurans from the Brazilian semi-arid. (United States)

    Madelaire, Carla Bonetti; Gomes, Fernando Ribeiro


    Anurans living in arid and semi-arid habitats are subjected to unpredictable rain patterns. Consequently, they should be prepared to reproduce at the onset of rain events. We investigated the covariation between calling behavior, testicular maturation, abdominal fat body index (FBI), plasma levels of androgens (T-DHT) and corticosterone (CORT) of males from three species of anurans in the Brazilian semi-arid during the reproductive period and drought. One of these species aestivates during the drought, while the other two species remain foraging. Although the three species display different behavioral strategies during the dry period, they present the same general reproductive patterns. T-DHT levels on the plasma and germinative cyst diameters were higher during the reproductive and breeding period compared to the drought. Additionally, the germinative cysts had all cell stages including sperm bundles during the dry season, however, it was only during the breeding event that free spermatozoa were found in the cyst lumen. These results suggest that these species present the reproductive pattern typical of desert anurans, consisting of opportunistic breeders that reproduce when triggered by a rain stimulus. Rhinella jimi and Pleurodema diplolister had higher CORT when males were calling. Moreover, Rhinella granulosa and P. diplolister showed lower FBI during breeding event, when males were calling. The high levels of CORT and lower FBI during reproductive period are associated, indicating that CORT modulates the recruitment of energy stores to prepare and maintain reproduction, particularly the expensive calling effort. Copyright © 2016 Elsevier Inc. All rights reserved.

  19. Genetic Variability and Symbiotic Efficiency of Erythrina velutina Willd. Root Nodule Bacteria from the Semi-Arid Region in Northeastern Brazil

    Directory of Open Access Journals (Sweden)

    Kelly Alexsandra Souza Menezes

    Full Text Available ABSTRACT Legume-rhizobia symbiosis is a cross-kingdom association that results in large amounts of nitrogen incorporated in food webs. For the Brazilian semi-arid region, data on genetic variability and symbiotic efficiency of Papilionoidae rhizobial communities are very scarce. The aim of this study was to evaluate the genetic variability and the symbiotic efficiency of eight rhizobial isolates obtained from “mulungu” (Erythrina velutina Willd. nodules. For 16S rRNA gene sequencing, the genomic DNA was extracted using a commercial kit, amplified with universal primers, and subjected to sequencing reactions. For the isolate ESA 71, PCR amplifications for nodC and nodA genes were attempted. Rhizobial efficiency was assessed by two greenhouse experiments. The first assay was carried out under gnotobiotic conditions, with sterile sand as a substrate; the second experiment was conducted in a non-sterile soil. For both experiments, the inoculation treatments consisted of a single inoculation of each isolate, in addition to a treatment with Bradyrhizobium elkanii BR 5609 as a reference strain. Furthermore, two non-inoculated control treatments, supplied and not supplied with mineral N, were also evaluated. Bacterial identification indicated that both α and β-rhizobia could be found in “mulungu” root nodules. Three isolates where classified within the Rhizobium genus, four bacteria belonged to Bradyrhizobium and one isolate clustered with Burkholderia. Positive amplification of an intragenic fragment of the nodA gene using a primer set to β-rhizobia could be found for ESA 71 (Burkholderia. All bacterial isolates were effective in colonizing “mulungu” roots. In the first experiment, all inoculated treatments and N fertilization increased the N concentration in “mulungu” shoot tissues. For total N in the shoots, the isolates ESA 70, ESA 72, and ESA 75 stood out. In the non-sterile substrate experiment, the isolates ESA 70, ESA 71, ESA

  20. Responses of Soil CO2 Emissions to Extreme Precipitation Regimes: a Simulation on Loess Soil in Semi-arid Regions (United States)

    Wang, R.; Zhao, M.; Hu, Y.; Guo, S.


    Responses of soil CO2 emission to natural precipitation play an essential role in regulating regional C cycling. With more erratic precipitation regimes, mostly likely of more frequent heavy rainstorms, projected into the future, extreme precipitation would potentially affect local soil moisture, plant growth, microbial communities, and further soil CO2 emissions. However, responses of soil CO2 emissions to extreme precipitation have not yet been systematically investigated. Such performances could be of particular importance for rainfed arable soil in semi-arid regions where soil microbial respiration stress is highly sensitive to temporal distribution of natural precipitation.In this study, a simulated experiment was conducted on bare loess soil from the semi-arid Chinese Loess Plateau. Three precipitation regimes with total precipitation amounts of 150 mm, 300 mm and 600 mm were carried out to simulate the extremely dry, business as usual, and extremely wet summer. The three regimes were individually materialized by wetting soils in a series of sub-events (10 mm or 150 mm). Co2 emissions from surface soil were continuously measured in-situ for one month. The results show that: 1) Evident CO2 emission pulses were observed immediately after applying sub-events, and cumulative CO2 emissions from events of total amount of 600 mm were greater than that from 150 mm. 3) In particular, for the same total amount of 600 mm, wetting regimes by applying four times of 150 mm sub-events resulted in 20% less CO2 emissions than by applying 60 times of 10 mm sub-events. This is mostly because its harsh 150 mm storms introduced more over-wet soil microbial respiration stress days (moisture > 28%). As opposed, for the same total amount of 150 mm, CO2 emissions from wetting regimes by applying 15 times of 10 mm sub-events were 22% lower than by wetting at once with 150 mm water, probably because its deficiency of soil moisture resulted in more over-dry soil microbial respiration

  1. Multi-criteria analysis for improving strategic environmental assessment of water programmes. A case study in semi-arid region of Brazil. (United States)

    Garfì, Marianna; Ferrer-Martí, Laia; Bonoli, Alessandra; Tondelli, Simona


    Multi-criteria analysis (MCA) is a family of decision-making tools that can be used in strategic environmental assessment (SEA) procedures to ensure that environmental, social and economic aspects are integrated into the design of human development strategies and planning, in order to increase the contribution of the environment and natural resources to poverty reduction. The aim of this paper is to highlight the contribution of a particular multi-criteria technique, the analytic hierarchy process (AHP), in two stages of the SEA procedure applied to water programmes in developing countries: the comparison of alternatives and monitoring. This proposal was validated through its application to a case study in Brazilian semi-arid region. The objective was to select and subsequently monitor the most appropriate programme for safe water availability. On the basis of the SEA results, a project was identified and implemented with successful results. In terms of comparisons of alternatives, AHP meets the requirements of human development programme assessment, including the importance of simplicity, a multidisciplinary and flexible approach, and a focus on the beneficiaries' concerns. With respect to monitoring, the study shows that AHP contributes to SEA by identifying the most appropriate indicators, in order to control the impacts of a project. Copyright © 2010 Elsevier Ltd. All rights reserved.

  2. Assessment of Groundwater Chemistry and Status in a Heavily Used Semi-Arid Region with Multivariate Statistical Analysis

    Directory of Open Access Journals (Sweden)

    Xuedi Zhang


    Full Text Available This hydrogeological study assessed the quality of phreatic water supplies across the semi-arid, traditional agricultural region of the Yinchuan region in northwest China, near the upper reaches of the Yellow River. We analyzed the chemical characteristics of water collected from 39 sampling stations before the 2011 summer-autumn irrigation period, using multivariate statistical analysis and geostatistical methods. We determined which factors influence the composition of groundwater, using principal component analysis (PCA and two modes of cluster analysis. PCA showed that the most important variables in the study area were the strong evaporation effect caused by the dry climate, dissolution of carbonate minerals and those containing F− and K−, and human activity including the treatment of domestic sewage and chemical fertilization. The Q-mode of cluster analysis identified three distinct water types that were distinguished by different chemical compositions, while the R-mode of analysis revealed two distinct clusters of sampling stations that appeared to be influenced by distinct sets of natural and/or anthropogenic factors.

  3. Chemical composition and potential ethanol yield of Jerusalem artichoke in a semi-arid region of China

    Directory of Open Access Journals (Sweden)

    Zu Xin Liu


    Full Text Available The study was aimed to evaluate the potential of existing genotypes of Jerusalem artichoke (Helianthus tuberosus L. as biomass feedstock for ethanol production. We investigated the biomass productivity and chemical composition of twenty-six Jerusalem artichoke clones grown in a semi-arid region of China. Jerusalem artichoke was demonstrated to be a sustainable feedstock for bioethanol production. All structural and non-structural carbohydrates in whole plant of Jerusalem artichoke could be 5000 L/ha. The above-ground biomass of Jerusalem artichoke could be a promising feedstock for cellulosic ethanol. The ethanol potential yield from cellulose and hemicellulose in aboveground biomass were 1821 to 5930 L/ha, contributing 29.8-66.4% of the total ethanol yield, which could be as high as that from switchgrass and sweet sorghum stem. Large variation among the investigated genotypes for carbohydrates makes it possible to select suitable clones to be used in bioethanol production in semiarid regions. Clones HB-3, HEN-3, IM-1, SC-1, SHX-3, SX-2 and ZJ-2 yielded tuber total soluble sugar higher than 4.0 t/ha. Clones BJ-4, HUB-2, HUN-2, QH-1, SD-2 and SHH-1 produced more than 5.0 t/ha cellulose and hemicellulose in above-ground biomass. Clones BJ-4 and HUB-2 have the highest ethanol potential based on structural carbohydrates. These clones were promising material if used as biofuel feedstock in this growth condition.

  4. Dimethylamine as a major alkyl amine species in particles and cloud water: Observations in semi-arid and coastal regions (United States)

    Youn, J.-S.; Crosbie, E.; Maudlin, L. C.; Wang, Z.; Sorooshian, A.


    Aerosol and cloud water measurements of dimethylamine (DMA), the most abundant amine in this study, were conducted in semi-arid (Tucson, Arizona) and marine (Nucleation in California Experiment, NiCE; central coast of California) areas. In both regions, DMA exhibits a unimodal aerosol mass size distribution with a dominant peak between 0.18 and 0.56 μm. Particulate DMA concentrations increase as a function of marine biogenic emissions, sulfate, BVOC emissions, and aerosol-phase water. Such data supports biogenic sources of DMA, aminium salt formation, and partitioning of DMA to condensed phases. DMA concentrations exhibit positive correlations with various trace elements and most especially vanadium, which warrants additional investigation. Cloud water DMA levels are enhanced significantly during wildfire periods unlike particulate DMA levels, including in droplet residual particles, due to effective dissolution of DMA into cloud water and probably DMA volatilization after drop evaporation. DMA:NH4+ molar ratios peak between 0.18 and 1.0 μm depending on the site and time of year, suggesting that DMA competes better with NH3 in those sizes in terms of reactive uptake by particles.

  5. Identification of suitable sites for rainwater harvesting structures in arid and semi-arid regions: A review

    Directory of Open Access Journals (Sweden)

    Ammar Adham


    Full Text Available Harvested rainwater is an alternative source of water in arid and semi-arid regions (ASARs around the world. Many researchers have developed and applied various methodologies and criteria to identify suitable sites and techniques for rainwater harvesting (RWH. Determining the best method or guidelines for site selection, however, is difficult. The main objective of this study was to define a general method for selecting suitable RWH sites in ASARs by assembling an inventory of the main methods and criteria developed during the last three decades. We categorised and compared four main methodologies of site selection from 48 studies published in scientific journals, reports of international organisations, or sources of information obtained from practitioners. We then identified three main sets of criteria for selecting RWH locations and the main characteristics of the most common RWH techniques used in ASARs. The methods were diverse, ranging from those based only on biophysical criteria to more integrated approaches including socio-economic criteria, especially after 2000. The most important criteria for the selection of suitable sites for RWH were slope, land use/cover, soil type, rainfall, distance to settlements/streams, and cost. The success rate of RWH projects tended to increase when these criteria were considered, but an objective evaluation of these selection methods is still lacking. Most studies now select RHW sites using geographic information systems in combination with hydrological models and multi-criteria analysis.

  6. Development of an Evapotranspiration Data Assimilation Technique for Streamflow Estimates: A Case Study in a Semi-Arid Region

    Directory of Open Access Journals (Sweden)

    Ying Zhang


    Full Text Available Streamflow estimates are substantially important as fresh water shortages increase in arid and semi-arid regions where evapotranspiration (ET is a significant contribution to the water balance. In this regard, evapotranspiration data can be assimilated into a distributed hydrological model (SWAT, Soil and Water Assessment Tool for improving streamflow estimates. The SWAT model has been widely used for streamflow estimations, but the applications combining SWAT and ET products were rare. Thus, this study aims to develop a SWAT-based evapotranspiration data assimilation system. In particular, SWAT is gridded at Hydrologic Response Unit (HRU level to incorporate gridded ET products acquired from the remote sensing-based ETMonitor model. In the modeling case, Gridded SWAT (GSWAT shows a good agreement of streamflow modeling with the original SWAT. Such a scant margin between them is due to the modeling domain mismatch caused by different HRU delineations. In the ET assimilation case, we carry out a synthetic data experiment to illustrate the state augmentation Direct Insertion (DI method and a real data experiment for the upper Heihe River Basin. The results demonstrate the benefits of the ET assimilation for improving hydrologic processes representations. In the future, more remotely sensed data can be assimilated into the data assimilation system to provide more reliable hydrological predictions.

  7. Structural variations among monocot emergent and amphibious species from lakes of the semi-arid region of Bahia, Brazil

    Directory of Open Access Journals (Sweden)

    KRB Leite

    Full Text Available Temporary lakes are common in the semi-arid region of the State of Bahia and form water mirrors in the rainy season. In this period, various vegetal species appear having different life forms adapted to the seasonality conditions of the rainfall regime. This work surveyed the adaptive anatomical structures of some emergent and amphibious monocot species occurring in these lakes. We studied the anatomy of roots, rhizomes, leaves and scapes of Cyperus odoratus, Oxycaryum cubense, Pycreus macrostachyos (Cyperaceae - amphibious species; and of Echinodorus grandiflorus (Alismataceae, Eichhornia paniculata (Pontederiaceae and Habenaria repens (Orchidaceae - emergent species. The anatomical features of the dermal, fundamental and vascular systems confirming the tendency of the adaptive convergence of these plants to temporary lacustrine the environment include: single layered epidermal cells with a thin cuticle layer in the aerial organs; the presence of air canals in all the organs; few or no supporting tissues; and less numerous conducting elements and thinner cell walls in the xylem. The reduction of the supporting tissues, the number of stomata, which can even be absent, and the number of conducting elements and the degree of cell wall lignification in the xylem of the emergent species is more accentuated than that of the amphibious species. The pattern of distribution of aerenchyma in the roots of the studied species was considered important to distinguish between amphibious and emergent life forms.

  8. Assessing anthropogenic impacts on limited water resources under semi-arid conditions: three-dimensional transient regional modelling in Jordan (United States)

    Rödiger, Tino; Magri, Fabien; Geyer, Stefan; Morandage, Shehan Tharaka; Ali Subah, H. E.; Alraggad, Marwan; Siebert, Christian


    Both increasing aridity and population growth strongly stress freshwater resources in semi-arid areas such as Jordan. The country's second largest governorate, Irbid, with over 1 million inhabitants, is already suffering from an annual water deficit of 25 million cubic meters (MCM). The population is expected to double within the next 20 years. Even without the large number of refugees from Syria, the deficit will likely increase to more then 50 MCM per year by 2035 The Governorate's exclusive resource is groundwater, abstracted by the extensive Al Arab and Kufr Asad well fields. This study presents the first three-dimensional transient regional groundwater flow model of the entire Wadi al Arab to answer important questions regarding the dynamic quality and availability of water within the catchment. Emphasis is given to the calculation and validation of the dynamic groundwater recharge, derived from a multi-proxy approach, including (1) a hydrological model covering a 30-years dataset, (2) groundwater level measurements and (3) information about springs. The model enables evaluation of the impact of abstraction on the flow regime and the groundwater budget of the resource. Sensitivity analyses of controlling parameters indicate that intense abstraction in the southern part of the Wadi al Arab system can result in critical water-level drops of 10 m at a distance of 16 km from the production wells. Moreover, modelling results suggest that observed head fluctuations are strongly controlled by anthropogenic abstraction rather than variable recharge rates due to climate changes.

  9. Soil surface moisture estimation over a semi-arid region using ENVISAT ASAR radar data for soil evaporation evaluation

    Directory of Open Access Journals (Sweden)

    M. Zribi


    Full Text Available The present paper proposes a method for the evaluation of soil evaporation, using soil moisture estimations based on radar satellite measurements. We present firstly an approach for the estimation and monitoring of soil moisture in a semi-arid region in North Africa, using ENVISAT ASAR images, over two types of vegetation covers. The first mapping process is dedicated solely to the monitoring of moisture variability related to rainfall events, over areas in the "non-irrigated olive tree" class of land use. The developed approach is based on a simple linear relationship between soil moisture and the backscattered radar signal normalised at a reference incidence angle. The second process is proposed over wheat fields, using an analysis of moisture variability due to both rainfall and irrigation. A semi-empirical model, based on the water-cloud model for vegetation correction, is used to retrieve soil moisture from the radar signal. Moisture mapping is carried out over wheat fields, showing high variability between irrigated and non-irrigated wheat covers. This analysis is based on a large database, including both ENVISAT ASAR and simultaneously acquired ground-truth measurements (moisture, vegetation, roughness, during the 2008–2009 vegetation cycle. Finally, a semi-empirical approach is proposed in order to relate surface moisture to the difference between soil evaporation and the climate demand, as defined by the potential evaporation. Mapping of the soil evaporation is proposed.

  10. Heritability of stem straightness and genetic correlations in Eucalyptus cladocalyx in the semi-arid region of Chile

    Directory of Open Access Journals (Sweden)

    Carlos Alberto Scapim


    Full Text Available The aim of this study was to determine genetic parameters for straightness of the trunk of Eucalyptus cladocalyx, witha view to the selection of straight trees, while keeping the impact on growth minimal. The tests were conducted at two locations inthe semi-arid region of Chile, using a randomized block design, with 30 replications and 49 half-sib families. The parameters wereestimated by a bi-character model of individual trees, using Bayesian inference by Gibbs algorithm. The heritability for stem straightnesswas shown to be moderate, with h2=0.40 [0.29-0.57]. Heritabilities for diameter and height were moderate: 0.30 [0.24-0.38]and 0.30 [0.22-0.44]. Genetic correlations between straightness and growth were statistically not different from zero. The genotypeenvironmentinteraction was not significant (p>0.05 for the traits. The moderate degree of genetic control allows significant geneticgains in environments under water stress.

  11. Regional differences in the surface temperature of Naked Neck laying hens in a semi-arid environment. (United States)

    de Souza, João Batista Freire; de Arruda, Alex Martins Varela; Domingos, Hérica Girlane Tertulino; de Macedo Costa, Leonardo Lelis


    The aim of this study was to evaluate the regional differences in the surface temperature of Naked Neck hens that were subjected to different temperatures in a semi-arid environment. The surface temperature was measured in four body regions (face, neck, legs and feathered area) of 60 Naked Neck hens. The following environmental variables were measured at the center of the shed: the black globe temperature (T G ), air temperature (T A ), wind speed (U) and relative humidity (R H ). The T A was divided into three classes: 1 (24.0-26.0 °C), 2 (26.1-28.9 °C) and 3 (29.0-31.0 °C). An analysis of variance was performed by the least squares method and a comparison of the means by the Tukey-Kramer test. The results showed a significant effect of T A class, the body region and the interaction between these two effects on the surface temperature. There was no significant difference between the T A classes for the face and neck. The legs and feathered area showed significant differences between the T A classes. Regarding the effect of body regions within each T A class, there was a significant difference among all regions in the three T A classes. In all T A classes the neck had the highest average followed by the face and legs. The feathered area showed the lowest average of the different T A classes. In conclusion, this study showed that there are regional differences in the surface temperature of Naked Neck hens, with the legs acting as thermal windows.

  12. Hydrological differentiation and spatial distribution of high altitude wetlands in a semi-arid Andean region derived from satellite data (United States)

    Otto, M.; Scherer, D.; Richters, J.


    High Altitude Wetlands of the Andes (HAWA) belong to a unique type of wetland within the semi-arid high Andean region. Knowledge about HAWA has been derived mainly from studies at single sites within different parts of the Andes at only small time scales. On the one hand, HAWA depend on water provided by glacier streams, snow melt or precipitation. On the other hand, they are suspected to influence hydrology through water retention and vegetation growth altering stream flow velocity. We derived HAWA land cover from satellite data at regional scale and analysed changes in connection with precipitation over the last decade. Perennial and temporal HAWA subtypes can be distinguished by seasonal changes of photosynthetically active vegetation (PAV) indicating the perennial or temporal availability of water during the year. HAWA have been delineated within a region of 12 800 km2 situated in the Northwest of Lake Titicaca. The multi-temporal classification method used Normalized Differenced Vegetation Index (NDVI) and Normalized Differenced Infrared Index (NDII) data derived from two Landsat ETM+ scenes at the end of austral winter (September 2000) and at the end of austral summer (May 2001). The mapping result indicates an unexpected high abundance of HAWA covering about 800 km2 of the study region (6 %). Annual HAWA mapping was computed using NDVI 16-day composites of Moderate Resolution Imaging Spectroradiometer (MODIS). Analyses on the relation between HAWA and precipitation was based on monthly precipitation data of the Tropical Rain Measurement Mission (TRMM 3B43) and MODIS Eight Day Maximum Snow Extent data (MOD10A2) from 2000 to 2010. We found HAWA subtype specific dependencies on precipitation conditions. A strong relation exists between perennial HAWA and snow fall (r2: 0.82) in dry austral winter months (June to August) and between temporal HAWA and precipitation (r2: 0.75) during austral summer (March to May). Annual changes in spatial extend of perennial HAWA

  13. Development of vegetation based soil quality indices for mineralized terrane in arid and semi-arid regions (United States)

    S. W. Blecker; L. L. Stillings; M. C. Amacher; J. A. Ippolito; N. M. DeCrappeo


    Soil quality indices (SQIs) are often management driven and attempt to describe key relationships between above- and below-ground parameters. In terrestrial systems, indices that were initially developed and modified for agroecosystems have been applied to non-agricultural systems in increasing number. We develop an SQI in arid and semi-arid ecosystems of the Western...

  14. A decision support approach for the selection and implementation of water harvesting techniques in arid and semi-arid regions

    NARCIS (Netherlands)

    Grum, Berhane; Hessel, Rudi; Kessler, Aad; Woldearegay, Kifle; Yazew, Eyasu; Ritsema, Coen; Geissen, Violette


    Water harvesting techniques (WHTs) improve the availability of water, which is essential for growing crops, especially in arid and semi-arid areas. A decision support approach can help in the selection of WHTs suitable under site-specific bio-physical and socio-economic conditions. This paper

  15. Modelling the topsoil carbon stock of agricultural lands with the Stochastic Gradient Treeboost in a semi-arid Mediterranean region

    KAUST Repository

    Schillaci, Calogero


    ETM+ panchromatic Band 8 were the most important predictors of SOC stock. Finally, SOC stocks were estimated for each land cover class. SGT predicted SOC stock better than GSOC and ISRIC for most data. This resulted in a percentage of data in the prediction confidence interval ± 50% compared to the observed values of 71.4%, 65.8%, and 50.7% for SGT, GSOC, and SGT, respectively. This consisted of a higher R2 and a slope (β) that was closer to 1 for the pseudo-regression constructed with SGT compared to GSOC and ISRIC. In conclusion, the results of the present study showed that the integration of RS with climatic and soil texture spatial data could strongly improve SOC prediction in a semi-arid Mediterranean region. In addition, the panchromatic band of Landsat 7 ETM + was more predictive compared to the conventionally used NDVI. This information is crucial to guiding decision-making processes, especially at a regional scale and/or in semi-arid Mediterranean areas. The model performance of the SGT could be further improved by adopting predictors with greater spatial resolutions. The results of the present experiment yield valuable information, especially for assessing climate change or land use change scenarios for SOC stocks and their spatial distribution.

  16. Hazard Analysis of Arid and Semi-Arid (ASAL) Regions of Kenya ...

    African Journals Online (AJOL)

    There is need to undertake a comprehensive hazard and Vulnerability analysis at regional and country level to inform interventions and other developmental activities. Women should be targeted at the community and leadership level, and efforts to empower them should be stepped up. Keywords: hazard, natural disaster, ...

  17. Uncertainties in downscaled relative humidity for a semi-arid region ...

    Indian Academy of Sciences (India)

    impact studies based on variables (IPCC 2001) and regional ... Future scenarios are derived in this study using trans- fer functions as they are conceptually simple and the most common statistical downscaling approach. (Schoof et ..... (b) Probability density function (PDF) of predictors whose grid points lie on land and sea.

  18. Field-based experimental water footprint study of sunflower growth in a semi-arid region of China. (United States)

    Qin, Lijie; Jin, Yinghua; Duan, Peili; He, Hongshi


    Field-scale changes in the water footprint during crop growth play an important role in formulating sustainable water utilisation strategies. This study aimed to explore field-scale variation in the water footprint of growing sunflowers in the western Jilin Province, China, during a 3-year field experiment. The goals of this study were to (1) determine the components of the 'blue' and 'green' water footprints for sunflowers sown with water, and (2) analyse variations in water footprints and soil water balance under different combinations of temperature and precipitation. Specific actions could be adopted to maintain sustainable agricultural water utilisation in the semi-arid region based on this study. The green, blue, and grey water footprints accounted for 93.7-94.7%, 0.4-0.5%, and 4.9-5.8%, respectively, of the water footprint of growing sunflowers. The green water footprint for effective precipitation during the growing season accounted for 58.8% in a normal drought year but 48.2% in an extreme drought year. When the effective precipitation during the growing season could not meet the green water use, a moisture deficit arose. This increase in the moisture deficit can have a significant impact on soil water balance. Green water was the primary water source for sunflower growth in the study area, where a scarcity of irrigation water during sunflower growth damaged the soil water balance, particularly in years with continuous drought. The combination of temperature and precipitation effected the growing environment, leading to differences in yield and water footprint. The field experiments in this area may benefit from further water footprint studies at the global, national and regional scale. © 2016 The Authors. Journal of The Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry. © 2016 The Authors. Journal of The Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of

  19. Sources and Pathways of Nutrients in the Semi-Arid Region of Beijing–Tianjin, China (United States)


    Semiarid regions worldwide are particularly prone to eutrophication, which causes immense ecological and economic problems. One region that is in transition and requires systematic research for effective intervention is the dry landscape of Beijing-Tianjin (P. R. China). We investigated the sources and spatiotemporal loads of nitrogen and phosphorus species over a one-year period in the Haihe catchment that drains the megacity of Beijing. Although wastewater treatment was improved in recent years, the rivers were heavily contaminated by 0.3–5.3 mgP L–1 and 3.0–49 mgN L–1, with toxic levels of nitrite (≥1 mgNO2–N L–1) and ammonia (≥0.6 mgNH3–N L–1). The average NH4+ (16.9 mgN L–1) increased by 160% compared to 1996-levels. Mass fluxes and δ15N-signatures revealed that nutrients originated almost exclusively from sewage. Furthermore, the water balance demonstrated that >90% of the polluted river water was diverted for irrigation, thereby threatening food safety and groundwater quality. Per capita loads of 1.42 kgN/yr and 115 gP/yr were comparable to the peak discharges typical of Europe and the United States in 1970–1990, but concentrations were 2–3 times higher in the Beijing–Tianjin region. Our research identified sewage as the predominant nutrient source in this semiarid region, which suggests that state-of-the-art wastewater treatment would drastically mitigate eutrophication and even more rapidly than was previously observed in Europe. PMID:22401269

  20. Consistency between Sweat Rate and Wet Bulb Globe Temperature for the Assessment of Heat Stress of People Working Outdoor in Arid and Semi-arid Regions

    Directory of Open Access Journals (Sweden)

    Hamidreza Heidari


    Full Text Available Background: Heat stress is common among workers in arid and semi-arid areas. In order to take every preventive measure to protect exposed workers against heat-related disorders, it is crucial to choose an appropriate index that accurately relates environmental parameters to physiological responses. Objective: To investigate the consistency between 2 heat stress and strain indices, ie, sweat rate and wet bulb globe temperature (WBGT, for the assessment of heat stress of people working outdoor in arid and semi-arid regions in Iran. Methods: During spring and summer, 136 randomly selected outdoor workers were enrolled in this study. Using a defined protocol, the sweat rate of these workers was measured 3 times a day. Simultaneously, the environmental parameters including WBGT index were recorded for each working station. Results: The level of agreement between sweat rate and WBGT was poor (κ<0.2. Based on sweat rate, no case exceeding the reference value was observed during the study. WBGT overestimated the heat stress in outdoor workers compared to sweat rate. Conclusion: It seems that the sweat rate standards may need some modifications related to real condition of work in arid and semi-arid regions in Iran. Moreover, it seems that judging workers solely based on monitoring their sweat rate in such regions, can probably result in underestimation of heat stress.

  1. Application of Bayesian Decision Networks for sustainable groundwater resources management in semi-arid regions (United States)

    Mohajerani, Hadis; Casper, Markus; Kholghi, Majid; Mosaedi, Abolfazl; Farmani, Raziyeh; Saadoddin, Amir; Meftah Halaghi, Mehdi


    This paper presents management of groundwater resource using a Bayesian Decision Network (BDN). The Kordkooy region in North East of Iran has been selected as study area. The region has been divided to three parts based on Transmissivity (T) and Electrical Conductivity (EC) values. The BDN parameters (prior probabilities and Conditional Probability Tables (CPTs) have been identified for each of the three zones. Three groups of management scenarios have been developed based on the two decision variables including "Crop pattern" and "Domestic water demand" across the three zones of the study area: 1) status quo management for all three zones representing current conditions. 2) the effect of change in cropping pattern on management endpoints and 3) the effect of increasing domestic water demand on management endpoints in the future. The outcomes arising from implementing each scenario have been predicted using the BDN for each of the zones. Results reveal that probability of drawdown in groundwater levels of southern areas is relatively high compared with other zones. Groundwater withdrawal from northern and northwestern areas of the study area should be limited due to the groundwater quality problems associated with shallow groundwater of these two zones. The ability of the Bayesian Decision Network to take into account key uncertainties in natural resources and performing a meaningful analysis in cases where there is not vast amount of information and observed data available -even based partly on expert opinion- emphasizes the advantage of this approach in groundwater resources management process, as limited data availability was a serious problem faced by groundwater resources of the study area.

  2. Hunting strategies used in the semi-arid region of northeastern Brazil

    Directory of Open Access Journals (Sweden)

    Lopez Luiz CS


    Full Text Available Abstract Hunting for wild animals is stimulated by the many different human uses of faunal resources, and these animals constitute important subsistence items in local communities in the Caatinga region. In order to gain access to these resources, hunters have developed a series of techniques and strategies that are described in the present work. The principal hunting techniques encountered were: waiting, especially directed towards hunting diurnal birds; calling ("arremedo", a technique in which the hunters imitate the animal's call to attract it to close range; hunting with dogs, a technique mostly used for capturing mammals; tracking, a technique used by only a few hunters who can recognize and follow animal tracks; and "facheado", in which the hunters go out at night with lanterns to catch birds in their nests. Additionally, many animal species are captured using mechanical traps. The types of traps used by the interviewees were: dead-fall traps ("quixó", iron-jaw snap traps ("arataca", wooden cages with bait ("arapuca", iron-cage traps ("gaiola', "visgo", multi-compartment bird cages ("alçapão", buried ground traps with pivoted tops ("fojo", and nooses and cages for carnivorous. The choice of which technique to use depends on the habits of the species being hunted, indicating that the hunters possess a wide knowledge of the biology of these animals. From a conservation perspective, active hunting techniques (waiting, imitation, hunting with dogs, and "facheado" have the greatest impact on the local fauna. The use of firearm and dogs brought greater efficiency to hunting activities. Additional studies concerning these hunting activities will be useful to contribute to proposals for management plans regulating hunting in the region – with the objective of attaining sustainable use of faunal resources of great importance to the local human communities.

  3. Evaluating relationships between urban land cover composition and evapotranspiration in semi-arid regions (United States)

    Manago, K. F.; Hogue, T. S.; Litvak, E.; Pataki, D. E.


    California experienced its most severe drought on record in 2013 and 2014, forcing the governor to call for the first statewide reductions in urban water use. This led to numerous water conservation efforts including turf removal and restrictions on outdoor irrigation. The decrease in irrigation across the city of Los Angeles has had major effects on regional hydrologic fluxes. Previous studies have found that conservation efforts have decreased streamflow but little work has been done on the impact of reduced irrigation on Evapotranspiration (ET). ET is one of the most difficult variables to measure as a result of its heterogeneity both spatially and temporally; yet, it is imperative in characterizing energy and hydrologic processes and in aiding water management decisions. Estimating ET is further complicated in urban regions where land cover composition is extremely variable, even at small scales. Irrigated landscape and impervious surfaces are two of the most common land cover types associated with urbanization, but they have opposite effects on ET. While numerous studies have evaluated changes in ET caused by urbanization, they have all produced varying results. This is expected as changes to ET are highly dependent on land cover composition. In this study, we modeled the relationship between ET and urban land cover change in Los Angeles. We utilized empirical equations derived from in situ measurements to calculate tree and irrigated turfgrass ET and compared the results to estimates based on remote-sensing and California Irrigation Management Information System (CIMIS) network of weather stations. We found that unshaded turfgrass largely increased ET compared to impervious surfaces, which reveals lavish irrigation practices. Trees also increased ET, but they provided shade that decreased ET from turf grass. With much of the western United States facing drought and water supply uncertainty due to climate change, understanding and predicting how land cover

  4. Hydrologic cycle and dynamics of aquatic macrophytes in two intermittent rivers of the semi-arid region of Brazil

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    F. Pedro

    Full Text Available The dynamics of aquatic macrophytes in intermittent rivers is generally related to the characteristics of the resistance and resilience of plants to hydrologic disturbances of flood and drought. In the semi-arid region of Brazil, intermittent rivers and streams are affected by disturbances with variable intensity, frequency, and duration throughout their hydrologic cycles. The aim of the present study is to determine the occurrence and variation of biomass of aquatic macrophyte species in two intermittent rivers of distinct hydrologic regimes. Their dynamics were determined with respect to resistance and resilience responses of macrophytes to flood and drought events by estimating the variation of biomass and productivity throughout two hydrologic cycles. Twenty-one visits were undertaken in the rewetting, drying, and drought phases in a permanent puddle in the Avelós stream and two temporary puddles in the Taperoá river, state of Paraíba, Northeast Brazil. The sampling was carried out by using the square method. Floods of different magnitudes occurred during the present study in the river and in the stream. The results showed that floods and droughts are determining factors in the occurrence of macrophytes and in the structure of their aquatic communities. The species richness of the aquatic macrophyte communities was lower in the puddles of the river and stream subject to flood events, when compared to areas where the run-off water is retained. At the beginning of the recolonization process, the intensity of the floods was decisive in the productivity and biomass of the aquatic macrophytes in the Taperoá river and the Avelós stream. In intermediate levels of disturbance, the largest values of productivity and biomass and the shortest time for starting the recolonization process occurred.

  5. Effects of different agricultural managements in soil microbial community structure in a semi-arid Mediterranean region. (United States)

    García-Orenes, Fuensanta; Morugan, Alicia; Mataix-Solera, Jorge; Scow, Kate


    Agriculture has been practiced in semi-arid Mediterranean regions for 10.000 years and in many cases these practices have been unsuitable causing land degradation for millennium and an important loss of soil quality. The land management can provide solutions to find the best agricultural practices in order to maintain the soil quality and get a sustainable agriculture model. Microbiological properties are the most sensitive and rapid indicators of soil perturbations and land use managements. The study of microbial community and diversity has an important interest as indicators of changes in soil quality. The main objective of this work was to asses the effect of different agricultural management practices in soil microbial community (evaluated as abundance of phospholipid fatty acids, PLFA). Four different treatments were selected, based on the most commonly practices applied by farmers in the study area, "El Teularet Experimental Station", located at the Enguera Range in the southern part of the Valencia province (eastern Spain). These treatments were: a) ploughing, b) herbicides c) mulch, using the types applied by organic farmers to develop a sustainable agriculture, such as oat straw and d) control that was established as plot where the treatment was abandonment after farming. An adjacent area with the same type of soil, but with natural vegetation was used as a standard or reference high quality soil. Soil samples were taken to evaluate the changes in microbial soil structure, analysing the abundance of PLFA. The results showed a major content of total PLFA in soils treated with oats straw, being these results similar to the content of PLFA in the soil with natural vegetation, also these soils were similar in the distribution of abundance of different PLFA studied. However, the herbicide and tillage treatments showed great differences regarding the soil used as reference (soil under natural vegetation).

  6. Lake Dynamics in Arid and Semi-Arid Regions of Central Asia and Their Responses to Climate Changes (United States)

    Li, J.; Sheng, Y.; Chen, X.


    As an essential component of the water cycles in arid and semi-arid regions of Central Asia, lakes provide valuable water resources to the fragile ecological environments and human beings. These lakes are mainly endorheic lakes sensitive to climate change and human impacts, and have been found experiencing great changes since 1960s. Mapping and monitoring these inland lakes facilitates our understanding of mechanisms of lake changes and their responses to the climatic and anthropogenic impacts. This paper uses both Landsat and satellite altimetry data to monitor both the seasonal and decadal changes of 30 typical inland lakes in Central Asia, and the lake change mechanisms are analyzed using historical meteorological data. Lake decadal changes are characterized using Landsat imagery in 1970s, 1990s, 2000s and 2009. Lake seasonal variations are characterized using high-temporal resolution satellite data to differentiate the seasonal lake variations from decadal lake changes. Seasonal variation analysis has revealed that these lakes have experienced significant changes within a year: > 0.5 m lake level change and over 5% in lake area change, and that they remain relatively stable between September and November. The analysis of decadal lake change during the stable seasons showes that lake change highly depends on lake types. Endorheic lakes in plains have larger change rates and have shrunk by 20% in areas, while open-basin lakes and alpine lakes remained relatively stable. Open lakes showed a shrinking trend in the last 20 years while alpine lakes showed an expanding trend. According to our analyses, different types of inland lakes presented different trends of area changes and level changes under the background of global warming effects in central Asia, and climate change is the prominent factor of inland lake changes.

  7. [Centipede (Scolopendra sp.) envenomation in a rural village of semi-arid region from Falcon State, Venezuela]. (United States)

    Acosta, María; Cazorla, Dalmiro


    Centipedes are invertebrate animals belonging to Phylum Arthropoda, Class Chilopoda, with a first pair of front legs that has been modified to form large, poisonous fangs connected to venomous glands. Likely, due to relatively benignity of the clinical manifestations, in Venezuela studies and research on centipede envenomation are virtually scarse. The objective of this work was to study, biological, clinical, epidemiological and treatment profiles of envenomation caused by centipedes from Río Seco town, semi-arid area of Falcon State, Venezuelan north-western region. Between August 2001 and July 2002, patients who referred centipede attack were attended in ambulatory emergency. These were clinically examined, and by means of anamnesis the site and time of bite were recorded. The centipede was collected for identification. Ringer solution and non steroid analgesic plus hidrocortisone (500 mg, one doses) were administered parenterally and intravenously, respectively. In one case with abscess, the patient received intravenously antibiotic therapy for 3 days plus orally for 4 days (500 mg every 6 hours). It was registered 17 cases bitten by Scolopendra sp., aged 3-52 years, 9 females and 8 males, with an estimated Incidence Density (ID) of 1.34/100 persons/year. The majority of the accidents prevailed in the dry season (100%), inside the home (70.59%), during the night (52.94%) and on the hands (29.41%). Most clinical manifestations were local: hyperthermia (100%), pain (64.7%) and paresthesias (52.94%). The majority of the patients resolved symptoms quickly between 2-24 hours after cessation of the treatment (analgesic + hydrocortisone). Due to be expected an ID between 1.28 x 10(-12) and 0.010 (X = 0.0021)/100 persons/year, thus envenomation rate at Rio Seco, Falcon State, Venezuela, can be considered of "very high" or epidemic. Sinanthropic and domestic habits of scolopendromorphae centipedes increase the frequency of stings. Only symptomatic therapeutical

  8. Index of Relative Importance of the Dietary Proportions of Sloth Bear (Melursus ursinus in Semi-Arid Region

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    Tana P. MEWADA


    Full Text Available Characterisations of the Sloth bear (Melursus ursinus diet during three distinguished seasons (monsoon, winter and summer in the semi-arid region of western India was under study. Diet was estimated using scat analysis, based on the calculation of Index of Relative Importance (IRI in order to determine the contribution of different food items in the Sloth bear diet. Sloth bears were observed to feed on a wide variety of prey items. They are specialized on insect prey, particularly termites or ants, and are considered as myrmecophagous. The myrmecophagousis character was confirmed by the highest score of insect part (IRI = 21.37 from the samples (n = 566, which was followed by Diospyros melanoxylon (IRI Score 13.51, Ficus spp. (IRI score 12.69 and Cassia fistula (IRI Score 10.13. Sloth bear dietary proportions varied among the three seasons under the study interval. Data suggested that the Sloth bear is essentially behaving as an omnivore, having similar diet (in terms of high incidence of wild fruits and insects with the bears inhabiting semi-arid regions. The opportunistic and generalist strategy of selecting diet ingredients has probably helped the species to survive in semi-arid habitat across the North Gujarat.

  9. Ethnopharmacological study of Stryphnodendron rotundifoliumin two communities in the semi-arid region of northeastern Brazil

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    Dayanne Rakelly de Oliveira

    Full Text Available This work describes the local knowledge of the medicinal use of Stryphnodendron rotundifolium Mart., Fabaceae, according to informants in two areas of the Araripe bioregion, in the Northeast Region of Brazil. We used interviews to investigate the ethnomedicinal use of the local species to determine the mode of use, frequency of administration, duration of treatment and restrictions of use. In traditional medicine, the use of S. rotundifoliumis associated with the treatment of inflammatory and infectious diseases. The part of the plant most used was the stem bark (86.11%, the predominant mode of preparation was immersion in water (52.83%, and oral administration was the most cited (48.43%. For inflammatory and infectious diseases, the treatment lasted 3-10 days and the frequency of administration was 2-3 times/day. For gastroprotective effects, treatment lasted up to 30 days, and the herb was administered 1-3 times/day. For pain complaints, the therapy varied from 2-3 days to continuous administration.The informants (46.87% did not mention restrictions of use, except for pregnant women, with a rate of 25%. A comparison of these results with the ethnopharmacological information from other studies showed that some of the traditional indications are scientifically supported by the literature or clinical studies. Nevertheless, the results showed that pharmacologists have not fully investigated all the possible bioactivities that healers credit to this plant.

  10. Design of municipal solid waste incinerator for use in semi-arid regions

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    M. B. Oumarou


    Full Text Available The paper treats the design of a municipal solid waste incinerator suited to the semiarid regions with northern Nigeria and Niger Republic in West Africa as the study area. Proximate and ultimate analyses results from the solid waste were used as basis for calculations, using standard formulas and correlations. The calorific value of the solid waste samples in the study area is not high enough to sustain an incineration process and it ranges from 5.024 MJ/kg to 5.867 MJ/kg. For these types of low calorific value fuels, the parallel flow concept was found to be the appropriate type of incinerator. The solid waste to be fed in the incinerator needs to be mixed with 50% of supplementary fuel in the form of readily available bagasse to make it up to the required lower calorific value. Major characteristics of the designed municipal solid waste incinerator were: total volume of incinerator chamber: 82.5 m3, length of the incinerator bed: 11m; width of the incinerator bed: 3m and height of the incinerator chamber: 2.5 m, while the suitable adiabatic flame temperature was found to be 1,587 K.

  11. Effects of harbor activities on sediment quality in a semi-arid region in Brazil. (United States)

    Moreira, Lucas B; Castro, Ítalo B; Hortellani, Marcos A; Sasaki, Silvio T; Taniguchi, Satie; Petti, Mônica A V; Fillmann, Gilberto; Sarkis, Jorge E S; Bícego, Márcia C; Costa-Lotufo, Leticia V; Abessa, Denis M S


    Tropical marine environments are rich in biodiversity and the presence of harbor activities in these areas can harm the coastal ecosystems. In this study, we assessed sediment quality of two harbors from a tropical region in Brazil by applying multiple lines-of-evidence approach. This approach included the integration of results on: (1) grain size, organic matter, organic carbon, nitrogen, phosphorus, trace metals, polycyclic aromatic hydrocarbons, linear alkylbenzenes, and tributyltin; (2) acute toxicity of whole sediments and chronic toxicity of liquid phases; and (3) benthic community descriptors. Our results revealed that the main contaminants detected in sediments from Mucuripe and Pecém Harbors were chromium, copper, nitrogen, zinc, and tributyltin. These toxicants arise from typical harbor activities. However, the changes in benthic composition and structure appear to depend on a combination of physical impacts, such as the deposition of fine sediments and the toxic potential of contaminants, especially in Mucuripe. Thus, apart from toxicants physical processes are important in describing risks. This information may assist in management and conservation of marine coastal areas. Copyright © 2016 Elsevier Inc. All rights reserved.

  12. Data on fluoride concentration levels in semi-arid region of Medak, Telangana, South India

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    Adimalla Narsimha


    Full Text Available According to the World Health Organization recommendation, the optimal fluoride concentration levels in drinking water have to be in the range of 0.5 and 1.5 mg/L since this permissible range is essential for normal mineralization of bones and teeth as well as for dental enamel formation in human's body Bell and budwig, 1970; Adimalla and Venkatayogi, 2017; Narsimha and Sudarshan, 2013, 2016; 2017 [1,2,4,5,6]. If continues intake of high fluoride (>1.5 water can severely cause dental and skeletal fluorosis. The investigated area people majorly depend on groundwater for drinking purposes and fluoride concentration ranged from 0.2 to 7.4 mg/L with mean concentration of 2.7 mg/L and data was compared with WHO guidelines for drinking purposes. Overall, data reveals that the 57% of groundwater samples data was not safe for drinking purposes. Therefore, distribution of fluoride in the groundwater of Medak region in Telangana was suggested to intake drinking water, which are below level of fluoride concentration in the groundwater and take care about health implications.

  13. Comparison of energy of irrigation regimes in sugar beet production in a semi-arid region

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    Topak, Ramazan; Sueheri, Sinan; Acar, Bilal [Department of Agricultural Structures and irrigation, Faculty of Agriculture, Selcuk University, 42075 Konya (Turkey)


    This study analyzed the effect of three levels of drip irrigation in sugar beet (Beta vulgaris L.) production in the Middle Anatolian region of Turkey. Two deficit irrigation treatments 75% and 50% of measured soil water depletion were compared with a full irrigation control treatment. In this paper, root yield, NEY (net energy yield), EEP (efficiency of energy production) and EWUE (energy water use efficiency) were investigated. Energy consumption of irrigation was found to be about 60% of total energy input in sugar beet production under full and deficit irrigation treatments. It was found that sugar beet had the highest EEP value (6.29) under the partial deficit irrigation (representing 75% of full irrigation). However, it was observed that full and severe deficit irrigation (representing 50% of full irrigation) treatments had a lower value. Results of this study indicated that the partial deficit drip irrigation technique can be applied in sugar beet production. In practice, deficit irrigation technique can reduce irrigation water use up to 25% compared to full irrigation technique. In addition, partial deficit drip irrigation technique may save 11.2% of total energy inputs, 16.1% of irrigation energy inputs, 21.2% of total fuel use and 25% of fuel use in irrigation. (author)

  14. The influence of agricultural management on soil's CO2 regime in semi-arid and arid regions (United States)

    Eshel, G.; Lifshithz, D.; Sternberg, M.; Ben-Dor, E.; Bonfile, D. J.; Arad, B.; Mingelgrin, U.; Fine, P.; Levy, G. J.


    Two of the more important parameters which may help us better evaluate the impact of agricultural practices on the global carbon cycle are the in-situ soil pCO2 profile and the corresponding CO2 fluxes to the atmosphere. In an ongoing study, we monitored the pCO2 to a depth of 5 m in two adjacent irrigated Avocado orchards in the coastal plain of Israel (semi-arid region), and to a depth of 2 m in a semi- arid rain-fed and a arid rain-fed wheat fields in southern Israel. The soil pCO2 profiles and CO2 fluxes measurements were supplemented by measurements of soil moisture and temperature. The results showed differences in the CO2 profiles (both in the depth of the highest concentration and its absolute values) and the CO2 fluxes between the orchards and the wheat fields as well as along the year. In the irrigated Avocado orchards pCO2 values were in the range of 1.5 kPa at a depth of 0.5 m up to 8 kPa at depths of 3-5 m (even though Avocado trees are characterized by shallow roots). Such levels could affect reactions (e.g., enhancement of inorganic carbon dissolution) that may take place in the soil and some of its chemical properties (e.g., pH). As expected, soil pCO2 was affected by soil moisture and temperature, and the distance from the trees. Maximum soil respiration was observed during the summer when the orchards are under irrigation. In the wheat fields pCO2 level ranged from 0.2- 0.6 kPa at a depth of 0.2 m to 0.2-1 kPa at depths of 1-1.5 m (in arid and semiarid respectively). These pCO2 levels were much lower than those obtained in the irrigated orchards and seemed to depend on the wheat growing cycle (high concentration were noted at depth of 1-1.5 m close to the end of grain filling) and precipitation gradient (arid vs. semiarid). Since CO2 fluxes are directly affected by the pCO2 profile and soil moister and temperature the CO2 fluxes from the wheat fields were much lower (0.02- 0.2 ml min-1 m-2) compared to those obtained from the Avocado orchards (2

  15. Too Much or Too Little? Eco-hydrology in Arid and Semi-arid Regions (United States)

    Toch, S. L.


    Around the world, disastrous effects of floods and droughts are painful evidence of our continuing struggle between human resource demands and the sustainability of our hydrologic ecosystems. Too much or too little rainfall is often deemed the culprit in these water crises, focusing on water "lacks and needs" instead of exploring the diverse mechanisms of the hydrologic functions and processes that sustain us. Applicable to regions around the world, this unified approach focuses on the connections between our human and ecological qualities, with user friendly concepts and how-to guides backed up by real life experiences. From the poorest parts of Africa to Urban France to the wealthiest state in the USA, examples from surface to groundwater to marine environments demonstrate how the links between vulnerable natural areas, and the basins that they support are integral to the availability, adequacy and accessibility of our drinking water. The interactions of watersheds within our diverse communities can link our resource practices with our human needs, serving as a basis for our ecological health and human well-being. Hydrologic ecosystems provide links to geographic and cultural information traversing physical and social boundaries. This international, community-based project demonstrates how our human resource demands can be managed within ecological constraints. An inter-disciplinary process is used that specifically explores the connections between ecological integrity and the preservation of potable supplies. A monitoring strategy is developed that assesses risk to human health from resource use practices, and explores the similarities and interactions between our human needs and those of the ecosystems in which we all must live together. This work is geared as a reference for groups, individuals and agencies concerned with land use and watershed management, a supplement for interdisciplinary high school through University curriculum, for professional

  16. Land Surface Model and Particle Swarm Optimization Algorithm Based on the Model-Optimization Method for Improving Soil Moisture Simulation in a Semi-Arid Region. (United States)

    Yang, Qidong; Zuo, Hongchao; Li, Weidong


    Improving the capability of land-surface process models to simulate soil moisture assists in better understanding the atmosphere-land interaction. In semi-arid regions, due to limited near-surface observational data and large errors in large-scale parameters obtained by the remote sensing method, there exist uncertainties in land surface parameters, which can cause large offsets between the simulated results of land-surface process models and the observational data for the soil moisture. In this study, observational data from the Semi-Arid Climate Observatory and Laboratory (SACOL) station in the semi-arid loess plateau of China were divided into three datasets: summer, autumn, and summer-autumn. By combing the particle swarm optimization (PSO) algorithm and the land-surface process model SHAW (Simultaneous Heat and Water), the soil and vegetation parameters that are related to the soil moisture but difficult to obtain by observations are optimized using three datasets. On this basis, the SHAW model was run with the optimized parameters to simulate the characteristics of the land-surface process in the semi-arid loess plateau. Simultaneously, the default SHAW model was run with the same atmospheric forcing as a comparison test. Simulation results revealed the following: parameters optimized by the particle swarm optimization algorithm in all simulation tests improved simulations of the soil moisture and latent heat flux; differences between simulated results and observational data are clearly reduced, but simulation tests involving the adoption of optimized parameters cannot simultaneously improve the simulation results for the net radiation, sensible heat flux, and soil temperature. Optimized soil and vegetation parameters based on different datasets have the same order of magnitude but are not identical; soil parameters only vary to a small degree, but the variation range of vegetation parameters is large.

  17. Hydrological differentiation and spatial distribution of high altitude wetlands in a semi-arid Andean region derived from satellite data

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    M. Otto


    Full Text Available High Altitude Wetlands of the Andes (HAWA belong to a unique type of wetland within the semi-arid high Andean region. Knowledge about HAWA has been derived mainly from studies at single sites within different parts of the Andes at only small time scales. On the one hand, HAWA depend on water provided by glacier streams, snow melt or precipitation. On the other hand, they are suspected to influence hydrology through water retention and vegetation growth altering stream flow velocity. We derived HAWA land cover from satellite data at regional scale and analysed changes in connection with precipitation over the last decade. Perennial and temporal HAWA subtypes can be distinguished by seasonal changes of photosynthetically active vegetation (PAV indicating the perennial or temporal availability of water during the year. HAWA have been delineated within a region of 12 800 km2 situated in the Northwest of Lake Titicaca. The multi-temporal classification method used Normalized Differenced Vegetation Index (NDVI and Normalized Differenced Infrared Index (NDII data derived from two Landsat ETM+ scenes at the end of austral winter (September 2000 and at the end of austral summer (May 2001. The mapping result indicates an unexpected high abundance of HAWA covering about 800 km2 of the study region (6 %. Annual HAWA mapping was computed using NDVI 16-day composites of Moderate Resolution Imaging Spectroradiometer (MODIS. Analyses on the relation between HAWA and precipitation was based on monthly precipitation data of the Tropical Rain Measurement Mission (TRMM 3B43 and MODIS Eight Day Maximum Snow Extent data (MOD10A2 from 2000 to 2010. We found HAWA subtype specific dependencies on precipitation conditions. A strong relation exists between perennial HAWA and snow fall (r2: 0.82 in dry austral winter months (June to August and between temporal HAWA and precipitation (r2: 0.75 during austral summer

  18. Population structure of the bivalve Anomalocardia brasiliana, (Gmelin, 1791 in the semi-arid estuarine region of northeastern Brazil

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    AML Rodrigues

    Full Text Available For several decades, the bivalve mollusk Anomalocardia brasiliana has been extracted in estuarine areas in the semi-arid region of northeastern Brazil. However, information on both dynamics and abundance of their populations are missing. In this context, the present study, therefore, investigated several aspects of the population structure of A. brasiliana on beaches near the estuary of the Apodi River in Northeast Brazil. The aims were to determine the population density of A. brasiliana during different times of the year, to estimate population parameters, and to relate species density and distribution to the abiotic characteristics of the region. Sampling was performed from March/2007 and May/2008, we collected samples of sediments and mollusks along 180 m transects in the intertidal area on the beaches Barra and Pernambuquinho, Grossos - RN. At each sampling site, samples of sediments and mollusks were collected in the intertidal area along 180 m transects. The highest and lowest average densities on Pernambuquinho beach were 1148 (April/2007, and 100 individuals.m–2 (May/ 2008, respectively. On Barra beach, the highest and lowest densities were 1813 (April/2007 and 951 individuals.m–2, (November/2007, respectively. The densities of A. brasiliana on both beaches were significantly different only in the months of January, April and May/ 2008. Length of the individuals ranged from 1 to 28 mm, with most individuals measuring between 22 and 24 mm. Length growth rate parameters for A. brasiliana were L∞ = 28.68 mm and k = 0.61 year–1 on Barra beach, and L∞ = 29.87 mm and k = 0.48 year–1 on Pernambuquinho beach. The growth rate curves for A. brasiliana suggest the presence of three well defined cohorts, thus pointing to a continuous reproduction cycle with peak recruitment between October/2007 and March/2008. A. brasiliana density decreased predominantly during the heavy rains of 2008, probably due to an accumulation of sediments and

  19. Diversity of the ground-dwelling ant fauna (Hymenoptera:Formicidae of a moist,montane forest of the semi-arid Brazilian "Nordeste "

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    N. L Hites


    Full Text Available Although the so called "green islands" of the semi-arid Brazilian "Nordeste" are economically, socially, and ecologically important, relatively little is known about their biodiversity. We present the results of the first survey of the ground-dwelling ant fauna of a secondary forest in the Serra de Baturité (4° 05’ - 4° 40’ S / 38° 30’ - 39° 10’ W, among the biggest of the moist, montane forests of the state of Ceará, Brazil. From February to March 2001, samples were taken every 50 m along twelve 200 m transects, each separated from the others by at least 50 m and cut on either side of a recreational trail. Where possible, two transects were cut from the same starting point on the trail, one on either side. At each sample site two methods were used, as recommended in the ALL protocol: a pitfall trap and the treatment of 1 m² of leaf litter with the Winkler extractor. The myrmecofauna of the Serra de Baturité is quite diverse: individuals from 72 species, 23 genera, and six subfamilies were collected. The observed patterns of specific richness show the same tendencies noted in other tropical regions, particularly the frequency of capture distribution with many rare and few abundant species. Differences with the Atlantic and Amazonian forests were also observed, especially the relative importance of the Ponerinae and Formicinae subfamilies, indicating a possible influence of the surrounding "caatinga" (savanna-like ecosystem on the myrmecofauna of the moist,montane forest. Rev. Biol. Trop. 53(1-2:165-173. Epub 2005 Jun 24Se presentan los resultados del primer inventario de la mirmecofauna del suelo en un parche de bosque montano húmedo del "Nordeste" semi-árido brasileño. Aunque estos parches o "islas verdes" son importantes económica, social, y ecológicamente, se conoce relativamente poco acerca de su biodiversidad. La investigación fue llevada a cabo en un bosque secundario en la Serra de Baturité, uno de los mayores del

  20. Fluvial transport and surface enrichment of arsenic in semi-arid mining regions: examples from the Mojave Desert, California. (United States)

    Kim, Christopher S; Stack, David H; Rytuba, James J


    As a result of extensive gold and silver mining in the Mojave Desert, southern California, mine wastes and tailings containing highly elevated arsenic (As) concentrations remain exposed at a number of former mining sites. Decades of weathering and erosion have contributed to the mobilization of As-enriched tailings, which now contaminate surrounding communities. Fluvial transport plays an intermittent yet important and relatively undocumented role in the migration and dispersal of As-contaminated mine wastes in semi-arid climates. Assessing the contribution of fluvial systems to tailings mobilization is critical in order to assess the distribution and long-term exposure potential of tailings in a mining-impacted environment. Extensive sampling, chemical analysis, and geospatial mapping of dry streambed (wash) sediments, tailings piles, alluvial fans, and rainwater runoff at multiple mine sites have aided the development of a conceptual model to explain the fluvial migration of mine wastes in semi-arid climates. Intense and episodic precipitation events mobilize mine wastes downstream and downslope as a series of discrete pulses, causing dispersion both down and lateral to washes with exponential decay behavior as distance from the source increases. Accordingly a quantitative model of arsenic concentrations in wash sediments, represented as a series of overlapping exponential power-law decay curves, results in the acceptable reproducibility of observed arsenic concentration patterns. Such a model can be transferable to other abandoned mine lands as a predictive tool for monitoring the fate and transport of arsenic and related contaminants in similar settings. Effective remediation of contaminated mine wastes in a semi-arid environment requires addressing concurrent changes in the amounts of potential tailings released through fluvial processes and the transport capacity of a wash.

  1. Reconstructing Holocene paleoenvironmental conditions in the semi-humid to semi-arid lowlands of the southeastern Caucasus region using ancient terrestrial land snails (United States)

    von Suchodoletz, Hans; Yanes, Yurena; Hausdorf, Bernhard; Faust, Dominik


    Unlike the western humid lowlands of the southern Caucasus region (Kolkheti Lowland), the Holocene paleoenvironmental evolution of the semi-humid to semi-arid lowlands in the southeastern part (Kura Lowland) has been minimally investigated. Because geographically close areas with different hydrological regimes may not follow equivalent paleoenvironmental histories, local profiles from each locale are necessary to accurately evaluate the paleoenvironmental evolution between contrasting settings. This study reconstructs the paleoenvironmental conditions of the Kura Lowlands using oxygen and carbon stable isotopes of ancient terrestrial land snails recovered from several Holocene fluvial sediment sequences of eastern Georgia. Snail shell samples were recovered from two main areas. The first area represents several profiles encompassing the period between 9.5 and 0.35 cal. ka BP in the semi-arid surroundings of Tbilisi that are outcropped along Kura and Shulaveris Ghele River (MAP = 450 - 560 mm/yr). The second area depicts sediments from one profile encompassing the period between ca. 8.0 and 1.6 cal. ka BP that is outcropped along the upper Alazani River in the semi-humid foothills of the Greater Caucasus (MAP = 720 mm/yr). The results from the semi-humid foothills of the Greater Caucasus suggest that humidity appears to have remained similar throughout the Holocene. In contrast, snails from the semi-arid Tbilisi region indicate that conditions were somewhat wetter during the first part of the Holocene (9.5 - 7 cal. ka BP), became gradually drier during the late Holocene and are the driest at present-day. This study illustrates that geographically close regions with differing hydrological regimes seem to be impacted by climate change in a different manner, and reinforces the need for developing local proxies rather than relying on regional-scale proxy data.

  2. Potential of the Thermal Infrared Wavelength Region to predict semi-arid Soil Surface Properties for Remote Sensing Monitoring (United States)

    Eisele, Andreas; Chabrillat, Sabine; Lau, Ian; Hecker, Christoph; Hewson, Robert; Carter, Dan; Wheaton, Buddy; Ong, Cindy; Cudahy, Thomas John; Kaufmann, Hermann


    Digital soil mapping with the means of passive remote sensing basically relies on the soils' spectral characteristics and an appropriate atmospheric window, where electromagnetic radiation transmits without significant attenuation. Traditionally the atmospheric window in the solar-reflective wavelength region (visible, VIS: 0.4 - 0.7 μm; near infrared, NIR: 0.7 - 1.1 μm; shortwave infrared, SWIR: 1.1 - 2.5 μm) has been used to quantify soil surface properties. However, spectral characteristics of semi-arid soils, typically have a coarse quartz rich texture and iron coatings that can limit the prediction of soil surface properties. In this study we investigated the potential of the atmospheric window in the thermal wavelength region (long wave infrared, LWIR: 8 - 14 μm) to predict soil surface properties such as the grain size distribution (texture) and the organic carbon content (SOC) for coarse-textured soils from the Australian wheat belt region. This region suffers soil loss due to wind erosion processes and large scale monitoring techniques, such as remote sensing, is urgently required to observe the dynamic changes of such soil properties. The coarse textured sandy soils of the investigated area require methods, which can measure the special spectral response of the quartz dominated mineralogy with iron oxide enriched grain coatings. By comparison, the spectroscopy using the solar-reflective region has limitations to discriminate such arid soil mineralogy and associated coatings. Such monitoring is important for observing potential desertification trends associated with coarsening of topsoil texture and reduction in SOC. In this laboratory study we identified the relevant LWIR wavelengths to predict these soil surface properties. The results showed the ability of multivariate analyses methods (PLSR) to predict these soil properties from the soil's spectral signature, where the texture parameters (clay and sand content) could be predicted well in the models

  3. Integrated meteorological and hydrological drought model: A management tool for proactive water resources planning of semi-arid regions (United States)

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


    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 characteristics to assess drought events for ultimate management of water resources, at small scales, i.e., sub-watersheds. The chosen study area is a sub-basin located at Karkheh watershed (western Iran), with five raingauge stations and one hydrometric station, located upstream and at the outlet, respectively, which represent 41-year of data. Prior to drought analysis, time series of precipitation and streamflow records are investigated for possible dependency/significant trend. Considering semi-arid nature of the study area, boxplots are utilized to graphically capture the rainy months, which are used to evaluate the degree of correlation between streamflow and precipitation records via nonparametric correlations. 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 (GOF) tests, Anderson-Darling is found preferable for defining copula distribution functions through GOF measures, i.e., Akaike and Bayesian information criteria and normalized root mean square error. Furthermore, a GOF method is proposed to evaluate the uncertainty associated with different copula models using the concept of entropy. A new bivariate drought modeling approach is proposed through copulas. The proposed index named standardized precipitation-streamflow index (SPSI) unlike common indices which are used in conjunction with station data, can be applied on a regional basis. SPDI is compared with widely applied streamflow drought index (SDI) and standardized precipitation index (SPI). To assess the homogeneity of the dependence structure of SPSI regionally, Kendall-τ and upper tail coefficient

  4. Responses of Soil Seed Bank and Vegetation to the Increasing Intensity of Human Disturbance in a Semi-Arid Region of Northern China

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    Cui Li


    Full Text Available To provide more insights into the responses of the soil seed bank and vegetation to human disturbance intensity, we selected four land use types, including: native grassland (no human disturbance, abandoned artificial grassland (light human disturbance, artificial grassland (moderate human disturbance, and farmland (severe human disturbance in a semi-arid climate of northern China. The species composition and density of the soil seed bank were measured, as well as the species composition and amount of vegetation. The native grassland had a significantly higher soil seed density and species richness than the other land use types. Moreover, the common species both in the soil seed bank and vegetation between the native grassland and other land use types gradually decreased as disturbance intensity increased. The abandoned artificial grassland and artificial grassland still had abundant soil seed banks according to their seed density (≥28.2% of the native grassland and species richness (≥70.0% of the native grassland to restore the vegetation. Conversely, it was hard to restore the vegetation on the farmland due to its low soil seed density (10.0% of the native grassland and species richness (40.0% of the native grassland. In conclusion, human disturbance would generate significant negative effects on the soil seed bank in desertified regions in a semi-arid climate; however, the soil seed bank in land use types with light/moderate disturbance are more adapted to vegetation restoration compared with land use types with severe disturbance in a semi-arid region.

  5. Spatial Distribution of Aboveground Carbon Stock of the Arboreal Vegetation in Brazilian Biomes of Savanna, Atlantic Forest and Semi-Arid Woodland (United States)


    The objective of this study was to map the spatial distribution of aboveground carbon stock (using Regression-kriging) of arboreal plants in the Atlantic Forest, Semi-arid woodland, and Savanna Biomes in Minas Gerais State, southeastern Brazil. The database used in this study was obtained from 163 forest fragments, totaling 4,146 plots of 1,000 m2 distributed in these Biomes. A geographical model for carbon stock estimation was parameterized as a function of Biome, latitude and altitude. This model was applied over the samples and the residuals generated were mapped based on geostatistical procedures, selecting the exponential semivariogram theoretical model for conducting ordinary Kriging. The aboveground carbon stock was found to have a greater concentration in the north of the State, where the largest contingent of native vegetation is located, mainly the Savanna Biome, with Wooded Savanna and Shrub Savanna phytophysiognomes. The largest weighted averages of carbon stock per hectare were found in the south-center region (48.6 Mg/ha) and in the southern part of the eastern region (48.4 Mg/ha) of Minas Gerais State, due to the greatest predominance of Atlantic Forest Biome forest fragments. The smallest weighted averages per hectare were found in the central (21.2 Mg/ha), northern (20.4 Mg/ha), and northwestern (20.7 Mg/ha) regions of Minas Gerais State, where Savanna Biome fragments are predominant, in the phytophysiognomes Wooded Savanna and Shrub Savanna. PMID:26066508

  6. Contamination risk and drinking water protection for a large-scale managed aquifer recharge site in a semi-arid karst region, Jordan (United States)

    Xanke, Julian; Liesch, Tanja; Goeppert, Nadine; Klinger, Jochen; Gassen, Niklas; Goldscheider, Nico


    Karst aquifers in semi-arid regions are particularly threatened by surface contamination, especially during winter seasons when extremely variable rainfall of high intensities prevails. An additional challenge is posed when managed recharge of storm water is applied, since karst aquifers display a high spatial variability of hydraulic properties. In these cases, adapted protection concepts are required to address the interaction of surface water and groundwater. In this study a combined protection approach for the surface catchment of the managed aquifer recharge site at the Wala reservoir in Jordan and the downstream Hidan wellfield, which are both subject to frequent bacteriological contamination, is developed. The variability of groundwater quality was evaluated by correlating contamination events to rainfall, and to recharge from the reservoir. Both trigger increased wadi flow downstream of the reservoir by surface runoff generation and groundwater seepage, respectively. A tracer test verified the major pathway of the surface flow into the underground by infiltrating from pools along Wadi Wala. An intrinsic karst vulnerability and risk map was adapted to the regional characteristics and developed to account for the catchment separation by the Wala Dam and the interaction of surface water and groundwater. Implementation of the proposed protection zones for the wellfield and the reservoir is highly recommended, since the results suggest an extreme contamination risk resulting from livestock farming, arable agriculture and human occupation along the wadi. The applied methods can be transferred to other managed aquifer recharge sites in similar karstic environments of semi-arid regions.

  7. Yield and quality responses of drip-irrigated spinach to different irrigation quantities in a semi-arid region with a high altitude

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    Yasemin KUSLU


    Full Text Available The effect of different irrigation quantities on the growth, marketable yield, crop quality (antioxidant activity, mineral and total phenolic content and irrigation water use efficiency (IWUE of spinach grown in a semi-arid region of high altitude (1795 m a.s.l. was determined. Plants were irrigated with three different irrigation quantities which determined considering 100 (I1, 85 (I2 and 70% (I3 of the evaporation obtained from a Class A pan. Irrigation quantities in the I1, I2 and I3 treatments as two years average were 290, 264.3 and 238.6 mm, respectively. The I1 treatment provided the highest growth, marketable yield (28.06 t*ha-1 and IWUE (9.7 kg*m-3. However, mineral and total phenolic content and antioxidant activity in the leaves of spinach were significantly higher under lower water application conditions. The I2 treatment resulted with the highest antioxidant activity and content of N, K, Mg, Na, Fe, Cu and total phenolics. As a result of the study, I1 treatment in spinach production could be suitable for water sufficient regions due to higher yield and IWUE. However, I2 treatment may be more appropriate for water scarce semi-arid regions of high altitude for obtaining higher minerals and antioxidant activity.

  8. Co-occurrence of arsenic and fluoride in groundwater of semi-arid regions in Latin America: genesis, mobility and remediation. (United States)

    Alarcón-Herrera, María Teresa; Bundschuh, Jochen; Nath, Bibhash; Nicolli, Hugo B; Gutierrez, Melida; Reyes-Gomez, Victor M; Nuñez, Daniel; Martín-Dominguez, Ignacio R; Sracek, Ondra


    Several million people around the world are currently exposed to excessive amounts of arsenic (As) and fluoride (F) in their drinking water. Although the individual toxic effects of As and F have been analyzed, there are few studies addressing their co-occurrences and water treatment options. Several studies conducted in arid and semi-arid regions of Latin America show that the co-occurrences of As and F in drinking water are linked to the volcaniclastic particles in the loess or alluvium, alkaline pH, and limited recharge. The As and F contamination results from water-rock interactions and may be accelerated by geothermal and mining activities, as well as by aquifer over-exploitation. These types of contamination are particularly pronounced in arid and semi-arid regions, where high As concentrations often show a direct relationship with high F concentrations. Enrichment of F is generally related to fluorite dissolution and it is also associated with high Cl, Br, and V concentrations. The methods of As and F removal, such as chemical precipitation followed by filtration and reverse osmosis, are currently being used at different scales and scenarios in Latin America. Although such technologies are available in Latin America, it is still urgent to develop technologies and methods capable of monitoring and removing both of these contaminants simultaneously from drinking water, with a particular focus towards small-scale rural operations. Copyright © 2012 Elsevier B.V. All rights reserved.

  9. Water Quality and Toxic Element Effects on Isohumic Soil Properties and Crops in Semi-arid Regions. (United States)

    Azouzi, Rim; Charef, Abdelkrim; Ayed, Lamia


    Treated wastewater (TWW) and freshwater used separately or within the same agricultural soil is a key element in soil parameter evolution, soil-plant pollution and crop yields. The long-term application of TWW increased CaCO3, P, N, K, TOC, metal contents, pH and salinity in isohumic soil in semi-arid and arid climates. Also, it was found that using freshwater after TWW within the same land leached soil compounds and pollutants. Consequently, a clear decline of salinity, pH, macronutrient and pollutant concentrations occured. Therefore, the economic profitability in topsoil decreased. TWW contributed to crop production increase, despite high fertilizer and metal concentrations in TWW and soil. Also, no toxic metal trace was detected in cultivated plants despite soil pollution. Occasional rainwater removed the stable part of fertilizers in topsoil and slightly improved plant development.

  10. Cost/benefit analysis of biomass energy supply options for rural smallholders in the semi-arid eastern part of Shinyanga Region in Tanzania

    Energy Technology Data Exchange (ETDEWEB)

    Wiskerke, W.T.; Dornburg, V.; Faaij, A.P.C. [Department of Science, Technology and Society, Utrecht University, Heidelberglaan 2, 3584 CS, Utrecht (Netherlands); Rubanza, C.D.K. [Tanzania Forestry Research Institute (TAFORI)/National Forest Resource Management and Agroforestry Centre (NACRAF), P.O. Box 1257, Shinyanga (Tanzania); Malimbwi, R.E. [Faculty of Forestry and Natural Resources, Sokoine University, P.O. Box 3010, Morogoro (Tanzania)


    This study analyzes the economic feasibility of sustainable smallholder bio-energy production under semi-arid conditions. The eastern part of Shinyanga region in Tanzania was chosen as a case study area. Three different sustainable biomass energy supply systems were compared by means of cost/benefit analysis: a small-scale forestation project for carbon sequestration, a short rotation woodlot and a Jatropha plantation, thereby using the produced Jatropha oil as a substitute for fuelwood or diesel. Rotational woodlots are most profitable with a Net Present Value of up to US${sub 2007} 1165/ha, a return on labour of up to US${sub 2007} 6.69/man-day and a fuelwood production cost of US${sub 2007} 0.53/GJ, compared to a local market price of US${sub 2007} 1.95/GJ. With a production cost of US${sub 2007} 19.60/GJ, Jatropha oil is too expensive to be used as an alternative for fuelwood. Instead it can be utilized economically as a diesel substitute, at an observed diesel cost of US${sub 2007} 1.49/l. The mean annual biomass increment (MAI) in semi-arid East Shinyanga is too low to collect sufficient benefits from trading forestation carbon credits under the Clean Development Mechanism (CDM) to cover the costs of forestation and forest management. (author)

  11. FIRST RECORD OF Hemidactylus agrius (SQUAMATA, GEKKONIDAE IN THICKETS OF Encholirium spectabile (Bromeliaceae IN THE BRAZILIAN SEMI-ARID

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    Jaqueiuto Silva Jorge


    Full Text Available Although highly diverse, few species of geckos (including the families Gekkonidae, Phylodactylidae and Sphaerodactylidae have been reported from bromeliad habitats, where the main goal of the present study is to provide preliminary information regarding the biology Hemidactylus agrius in association with  bromeliad (Encholirium spectabile growing on rock outcrops in the Agreste region, northeastern of Brazil, where the field work was carried out from December 2009 through September 2010 during a survey of the herpetofauna in Santa Maria municipality, during this study we report the occurrence of Hemidactylus agrius in touceiras of Encholirium spectabile, where in one night more than fifteen exemplars were observed, this report represent a great importance of conservation of this species, because this is considered a rare species and this report is a good and new notice for conservation of the H. agrius population in association with bromeliads of the genera Encholirium.

  12. Daily global solar radiation modelling using multi-layer perceptron neural networks in semi-arid region

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    Mawloud GUERMOUI


    Full Text Available Accurate estimation of Daily Global Solar Radiation (DGSR has been a major goal for solar energy application. However, solar radiation measurements are not a simple task for several reasons. In the cases where data are not available, it is very common the use of computational models to estimate the missing data, which are based mainly of the search for relationships between weather variables, such as temperature, humidity, sunshine duration, etc. In this respect, the present study focuses on the development of artificial neural network (ANN model for estimation of daily global solar radiation on horizontal surface in Ghardaia city (South Algeria. In this analysis back-propagation algorithm is applied. Daily mean air temperature, relative humidity and sunshine duration was used as climatic inputs parameters, while the daily global solar radiation (DGSR was the only output of the ANN. We have evaluated Multi-Layer Perceptron (MLP models to estimate DGSR using three year of measurement (2005-2008. It was found that MLP-model based on sunshine duration and mean air temperature give accurate results in term of Mean Absolute Bias Error, Root Mean Square Error, Relative Square Error and Correlation Coefficient. The obtained values of these indicators are 0.67 MJ/m², 1.28 MJ/m², 6.12%and 98.18%, respectively which shows that MLP is highly qualified for DGSR estimation in semi-arid climates.

  13. Soil temperature investigations using satellite acquired thermal-infrared data in semi-arid regions. Thesis. Final Report; [Utah (United States)

    Day, R. L.; Petersen, G. W.


    Thermal-infrared data from the Heat Capacity Mapping Mission satellite were used to map the spatial distribution of diurnal surface temperatures and to estimate mean annual soil temperatures (MAST) and annual surface temperature amplitudes (AMP) in semi-arid east central Utah. Diurnal data with minimal snow and cloud cover were selected for five dates throughout a yearly period and geometrically co-registered. Rubber-sheet stretching was aided by the WARP program which allowed preview of image transformations. Daytime maximum and nighttime minimum temperatures were averaged to generation average daily temperature (ADT) data set for each of the five dates. Five ADT values for each pixel were used to fit a sine curve describing the theoretical annual surface temperature response as defined by a solution of a one-dimensinal heat flow equation. Linearization of the equation produced estimates of MAST and AMP plus associated confidence statistics. MAST values were grouped into classes and displayed on a color video screen. Diurnal surface temperatures and MAST were primarily correlated with elevation.


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    Deeksha Gaur


    Full Text Available Thermophilic organisms can be defined as, micro-organisms which are adapted to survive at high temperatures. The enzymes secreted by thermophilic bacteria are capable of catalyzing biochemical reactions at high temperatures. Thermophilic bacteria are able to produce thermostable lipolytic enzymes (capable of degradation of lipid at temperatures higher than mesophilic bacteria. Therefore, the isolation of thermophilic bacteria from natural sources and their identification are quite beneficial in terms of discovering thermostable lipase enzymes. Due to great temperature fluctuation in hot arid and semi-arid region of Rajasthan, this area could serve as a good source for new thermophilic lipase producing bacteria with novel industrially important properties. The main objective of this research is the isolation and estimation of industrially important thermophilic lipase enzyme produced by thermophilic bacteria, isolated from arid and semi-arid region of Rajasthan. For this research purpose soil samples were collected from Churu, Sikar and Jhunjunu regions of Rajasthan. Total 16 bacterial strains were isolated and among only 2 thermostable lipolytic enzyme producing bacteria were charcterized. The thermostable lipolytic enzyme was estimated by qualitative and quantitative experiments. The isolates were identified as Bacillus sp. by microscopic, biochemical and molecular characterization. The optimum enzyme activity was observed at pH 8, temperature 60°C and 6% salt concentrations at 24 hrs time duration. Lipolytic enzyme find useful in a variety of biotechnological fields such as food and dairy (cheese ripening, flavour development, detergent, pharmaceutical (naproxen, ibuprofen, agrochemical (insecticide, pesticide and oleochemical (fat and oil hydrolysis, biosurfactant synthesis industries. Lipolytic enzyme can be further used in many newer areas where they can serve as potential biocatalysts.

  15. The photovoltaic solar technology in a semi-arid Piaui region: case study; A tecnologia solar fotovoltaica no semi-arido piauiense: estudo de caso

    Energy Technology Data Exchange (ETDEWEB)

    Moraes, Albemerc Moura de; Trigoso, Federico B. Morante [Universidade Federal do ABC (UFABC), Santo Andre, SP (Brazil). Centro de Engenharia, Modelagem e Ciencias Sociais Aplicadas. Programa de Pos Graduacao em Energia


    The following work has as objective to present some results of a research of field carried through in the Piaui semi-arid region that it aimed at to verify the use of the photovoltaic solar technology. For this six questionnaires in three rural communities of three municipal territories of the State in the valley of the river Caninde had been applied. It was verified that due to lack of maintenance of these systems good part of them left to still function in the first years of its installation. Although this almost all the interviewed ones had revealed signal of approval to the electric energy proceeding from these systems for the community use, however they had questioned the lack of maintenance of these and had revealed interested in possessing access in its residences of this so important good is useful, the electricity. (author)

  16. Utilização de água salina e condicionador de solo na produção de beterraba no semi-árido brasileiro Effect of saline water and soil conditioner on sugar beet yield in the Brazilian semi-arid region

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    Gilberto G. Cordeiro


    Full Text Available O experimento foi conduzido no Campo Experimental da Embrapa Semi-Árido em Petrolina - PE, no primeiro semestre de 1997 com o objetivo de avaliar o efeito de diferentes níveis de salinidade da água de irrigação e do condicionador de solo Sper Sal (ácido polimaléico na produção de beterraba (Beta vulgaris L., cultivar Early Wonder. O delineamento experimental foi de blocos ao acaso com quatro repetições. Os tratamentos foram: água com condutividade elétrica de 0,1 (água do Rio São Francisco - testemunha 4 e 8 dS/m e água com condutividade elétrica 0,1, 4 e 8 dS/m mais Sper Sal, com parcelas de 2 m². Os resultados obtidos mostraram que as produtividades variaram de 20,2 a 65,4 t/ha para os tratamentos irrigados com água salina mais Sper Sal e água do Rio São Francisco, respectivamente. Não se verificou diferença significativa na produtividade quando do uso de água com níveis de salinidade de 4 e 8 dS/m, cujas produtividades foram 29,4 e 26,3 t/ha respectivamente. Nos tratamentos com Sper Sal, observou-se que na concentração salina de 4 dS/m, o condicionador de solo demonstrou ser mais eficiente, em relação à concentração de 8 dS/m.An experiment was carried out at an experimental field in Embrapa Semi-arid, Petrolina - PE, during the first semester of 1997, with the objective of evaluating the effect of different irrigation water salinity levels, with and without the soil conditioner Sper Sal (polymaleic acid, on the yield of sugar beet (Beta vulgaris L., cv. Early Wonder. The experiment was set up in complete randomized block design, with four replications. Six treatments were tested: water with electrical conductivity of 0.1 (control, 4 and 8 dS/m, and the levels of electrical conductivity cited above plus Sper salt. The size of the plots was 2m². The results obtained showed that the yield varied from 20.2 to 65.4 t/ha, respectively, for irrigation treatments of saline with Sper Sal and water from the S

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

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


    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. Occurrence and identification of the etiologic agents of plant diseases in cactus (Opuntia ficus-indica Mill. in the semi-arid region of Paraiba

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    Anne Evelyne Franco de Souza


    Full Text Available Cactus forage (Opuntia ficus-indica Mill., intensely cultivated in dry regions of northeast Brazil, although well adapted to the harsh semi-arid climate is affected by major problems such as pests and diseases, responsible for significant losses in production. This study aimed to investigate the occurrence and diversity of the etiologic agents of diseases of cactus cultivated in 38 municipalities in the semi-arid region of Paraiba. The analyses were conducted and processed at the Laboratory of Phytopathology of the Centro de Ciências Agrárias da Universidade Federal da Paraíba, in Areia - PB. Starting from sick cladodes isolations, multiplications and identifications of the found microorganisms were made. The identification of the microorganisms was achieved through observations of the macro and micromorphological characteristics of the cultures and tests of Gram and pathogenicity. Great incidence and diversity of microorganisms was verified in the cacti researched, but the highest occurrence was mainly that of fungus. The fungi of widest occurrence were: Scytallidium lignicola, Alternate tenuis, Macrophomina phaseolina, Cladosporium cladosporides, Lasiodiplodia theobromae, Fusarium oxysporum f. sp. opuntiarum, Curvularia lunata, Aspergillus niger, Nigrospora sphaerica, Colletotrichum gloeosporioides, Exserohilum turcicum, Pestalotia pitospora, Rhizopus stolonifer, Rhizoctonia solani and Sphaceloma protearum. A bacterium was also detected that was suspected to belong to the Erwinia sp. strain. Satisfaction of the Postulates of Koch proved the infectious nature of the detected microorganisms. High occurrence of the fungus S. lignicola, an agent of scale rot disease in 100% of the places researched, was observed. This fact is of great concern, since the progression of the disease can cause significant losses in production.

  19. Occurrence and identification of the etiologic agents of plant diseases in cactus (Opuntia ficus-indica Mill. in the semi-arid region of Paraiba

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    Anne Evelyne Franco de Souza


    Full Text Available Cactus forage (Opuntia ficus-indica Mill., intensely cultivated in dry regions of northeast Brazil, although well adapted to the harsh semi-arid climate is affected by major problems such as pests and diseases, responsible for significant losses in production. This study aimed to investigate the occurrence and diversity of the etiologic agents of diseases of cactus cultivated in 38 municipalities in the semi-arid region of Paraiba. The analyses were conducted and processed at the Laboratory of Phytopathology of the Centro de Ciências Agrárias da Universidade Federal da Paraíba, in Areia – PB. Starting from sick cladodes isolations, multiplications and identifications of the found microorganisms were made. The identification of the microorganisms was achieved through observations of the macro and micromorphological characteristics of the cultures and tests of Gram and pathogenicity. Great incidence and diversity of microorganisms was verified in the cacti researched, but the highest occurrence was mainly that of fungus. The fungi of widest occurrence were: Scytallidium lignicola, Alternate tenuis, Macrophomina phaseolina, Cladosporium cladosporides, Lasiodiplodia theobromae, Fusarium oxysporum f. sp. opuntiarum, Curvularia lunata, Aspergillus niger, Nigrospora sphaerica, Colletotrichum gloeosporioides, Exserohilum turcicum, Pestalotia pitospora, Rhizopus stolonifer, Rhizoctonia solani and Sphaceloma protearum. A bacterium was also detected that was suspected to belong to the Erwinia sp. strain. Satisfaction of the Postulates of Koch proved the infectious nature of the detected microorganisms. High occurrence of the fungus S. lignicola, an agent of scale rot disease in 100% of the places researched, was observed. This fact is of great concern, since the progression of the disease can cause significant losses in production.

  20. Trends and variations of pH and hardness in a typical semi-arid river in a monsoon climate region during 1985-2009. (United States)

    Hao, Shaonan; Li, Xuyong; Jiang, Yan; Zhao, Hongtao; Yang, Lei


    The rapid growth of urbanization and industrialization, along with dramatic climate change, has strongly influenced hydrochemical characteristics in recent decades in China and thus could cause the variation of pH and general total hardness of a river. To explore such variations and their potential influencing factors in a river of the monsoon climate region, we analyzed a long-term monitoring dataset of pH, SO4 (2-), NOx, general total hardness (GH), Mg(2+), Ca(2+), and Cl(-) in surface water and groundwater in the Luan River basin from 1985 to 2009. The nonparametric Seasonal Kendall trend test was used to test the long-term trends of pH and GH. Relationship between the affecting factors, pH and GH were discussed. Results showed that pH showed a decreasing trend and that GH had an increasing trend in the long-term. Seasonal variation of pH and GH was mainly due to the typical monsoon climate. Results of correlation analysis showed that the unit area usage amounts of chemical fertilizer, NO3 (-), and SO4 (2-) were negatively correlated with pH in groundwater. In addition, mining activity affected GH spatial variation. Acid deposition, drought, and increasing the use of chemical fertilizers would contribute to the acidification trend, and mining activities would affect the spatial variation of GH. Variations of precipitation and runoff in semi-arid monsoon climate areas had significant influences on the pH and GH. Our findings implied that human activities played a critical role in river acidification in the semi-arid monsoon climate region of northern China.

  1. Feed handling of lactating crossbred cows maintained in a semi-arid region during the hot season: physiological parameters, ingestive behavior and performance. (United States)

    de Paula Xavier de Andrade, Rafael; de Andrade Ferreira, Marcelo; de Azevedo, Marcílio; da Silva, Emmanuelle Cordeiro; Urbano, Stela Antas; da Conceição, Maria Gabriela; de Lima Silva, Janaina


    The effects of time of feed delivery (14.00 hours; 14.00 and 20.00 hours; 16.00 and 18.00 hours) on the physiological parameters, ingestive behavior, nutrient intake and production of lactating cows maintained in a semi-arid region during the hot season were evaluated. Regardless of treatment, all animals received the first feeding supply at 06.00 hours. Eight cows with an average body weight of 600 kg, average milk yield of 20 kg/day and 80 days in milk were utilized. The rectal temperature, respiratory rate and sweating rate were not affected (P > 0.05), with average values of 38.5°C, 53.8 movements/min and 104 g/m2 /h respectively. There was no effect (P > 0.05) on the eating time (314 min/day), ruminating time (564 min/day), drinking time (61 min/day) and idle time (502 min/day). Similarly, the intake of nutrients and performance of lactating cows were not affected (P > 0.05), with average dry matter intake of 19.8 kg/day, 4% fat-corrected milk of 20.6 kg/day and milk fat concentration of 4.03 g/100 g. Since the behavior and performance have not altered, any times of feed delivery evaluated could be used to crossbred Holstein × Zebu cows maintained on a feedlot in semi-arid regions during the hot season. © 2016 Japanese Society of Animal Science.

  2. Ectoparasite Infestations and Canine Infection by Rickettsiae and Ehrlichiae in a Semi-Arid Region of Northeastern Brazil. (United States)

    Araes-Santos, Ana Isabel; Moraes-Filho, Jonas; Peixoto, Renata M; Spolidorio, Mariana G; Azevedo, Sérgio S; Costa, Mateus M; Labruna, Marcelo B; Horta, Mauricio C


    This study investigated the prevalence of Rickettsia spp. and Ehrlichia canis infection in dogs and their ectoparasites from rural and urban areas of two municipalities, Petrolina and Juazeiro, within a semiarid region (Caatinga biome) of northeastern Brazil, by immunofluorescence assay (IFA) and polymerase chain reaction (PCR). Overall, 12.1% (61/504) and 23.0% (116/504) of canine plasma samples had antibodies reactive to Rickettsia spp. and E. canis. E. canis DNA was detected by PCR in 8.3% (42/504) of canine blood samples, whereas no blood sample was positive for Rickettsia spp. The infection by E. canis was determined by PCR in 4.9% (14/285) Rhipicephalus sanguineus sensu lato (s.l.) ticks and by Rickettsia felis in 1.1% (3/285) and 40.6% (74/182) ticks and fleas, respectively. Multivariate regression analyses revealed that canine seropositivity to Rickettsia spp. was associated statistically with the variables "to reside in Petrolina" and "presence of ectoparasites." Our results indicate that canine infection by E. canis might be endemic in the Caatinga biome as it is in other Brazilian biomes. Although no previous serosurvey for Rickettsia spp. has been conducted on dogs from the Caatinga biome, our values are much lower than the ones reported for rural dogs from other Brazilian biomes. These differences are likely related to the semiarid climate of the aatinga biome, which minimizes the exposure of rural dogs to Amblyomma spp. ticks, the most common vectors of Rickettsia spp. in Brazil. Considering that dogs are excellent sentinels for human exposure to Rickettsia spp., we can infer that the risks of human acquiring tick-borne rickettsiosis in the Caatinga region of the present study are low. The rickettsial infection rates in fleas and ticks were not related to canine seropositivity; i.e., areas with higher Rickettsia infection rates in fleas had the lowest canine seroreactivity to Rickettsia spp.

  3. Application of Dempster-Shafer theory, spatial analysis and remote sensing for groundwater potentiality and nitrate pollution analysis in the semi-arid region of Khuzestan, Iran. (United States)

    Rahmati, Omid; Melesse, Assefa M


    Effective management and sustainable development of groundwater resources of arid and semi-arid environments require monitoring of groundwater quality and quantity. The aim of this paper is to develop a reasonable methodological framework for producing the suitability map for drinking water through the geographic information system, remote sensing and field surveys of the Andimeshk-Dezful, Khozestan province, Iran as a semi-arid region. This study investigated the delineation of groundwater potential zone based on Dempster-Shafer (DS) theory of evidence and evaluate its applicability for groundwater potentiality mapping. The study also analyzed the spatial distribution of groundwater nitrate concentration; and produced the suitability map for drinking water. The study has been carried out with the following steps: i) creation of maps of groundwater conditioning factors; ii) assessment of groundwater occurrence characteristics; iii) creation of groundwater potentiality map (GPM) and model validation; iv) collection and chemical analysis of water samples; v) assessment of groundwater nitrate pollution; and vi) creation of groundwater potentiality and quality map. The performance of the DS was also evaluated using the receiver operating characteristic (ROC) curve method and pumping test data to ensure its generalization ability, which eventually, the GPM showed 87.76% accuracy. The detailed analysis of groundwater potentiality and quality revealed that the 'non acceptable' areas covers an area of about 1479km(2) (60%). The study will provide significant information for groundwater management and exploitation in areas where groundwater is a major source of water and its exploration is critical to support drinking water need. Copyright © 2016 Elsevier B.V. All rights reserved.

  4. Políticas públicas de recursos hídricos para o semi-árido Public water resources policy for the semi-arid region

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    José Almir Cirilo


    Full Text Available As características climáticas e socioeconômicas do semi-árido brasileiro requerem tecnologias específicas de utilização e conservação dos recursos hídricos. É preciso analisar as alternativas de obtenção de água para usos diversos. Em contraposição às formas tradicionais de acumular água em pequenos reservatórios de superfície (açudes e perfuração de poços no cristalino, têm-se buscado alternativas como poços de grande profundidade nas áreas sedimentares, metodologias para redução da evaporação e controle da salinização, destinação e uso de efluentes. Por fim, obras de integração de bacias hidrográficas e transporte de água a grande distância começam a ser construídas na região. A abordagem dessas diferentes políticas hídricas para o semi-árido é o objetivo deste trabalho.The climatic, social and economic characteristics in the Brazilian semi-arid region require specific technologies of water resources uses and conservation. So, many alternatives for clean water acquisition must be analyzed. In opposition to the traditional way of accumulating water in small surface reservoirs and perforation of wells in crystalline terrains, alternatives have been looking like great depth wells in sedimentary areas, methodologies for evaporation reduction and salinization control, destination and use of effluents. Finally, works for river basins integration and water transport over long distances are starting to be built in Northeast region. The approach in those water policies for the Brazilian semi-arid region is the purpose of this paper.

  5. Dynamics and sources of soil organic C following afforestation of croplands with poplar in a semi-arid region in northeast China.

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    Ya-Lin Hu

    Full Text Available Afforestation of former croplands has been proposed as a promising way to mitigate rising atmospheric CO2 concentration in view of the commitment to the Kyoto Protocol. Central to this C sequestration is the dynamics of soil organic C (SOC storage and stability with the development of afforested plantations. Our previous study showed that SOC storage was not changed after afforestation except for the 0-10 cm layer in a semi-arid region of Keerqin Sandy Lands, northeast China. In this study, soil organic C was further separated into light and heavy fractions using the density fractionation method, and their organic C concentration and (13C signature were analyzed to investigate the turnover of old vs. new SOC in the afforested soils. Surface layer (0-10 cm soil samples were collected from 14 paired plots of poplar (Populus × xiaozhuanica W. Y. Hsu & Liang plantations with different stand basal areas (the sum of the cross-sectional area of all live trees in a stand, ranging from 0.2 to 32.6 m(2 ha(-1, and reference maize (Zea mays L. croplands at the same sites as our previous study. Soil ΔC stocks (ΔC refers to the difference in SOC content between a poplar plantation and the paired cropland in bulk soil and light fraction were positively correlated with stand basal area (R (2 = 0.48, p<0.01 and R (2 = 0.40, p = 0.02, respectively, but not for the heavy fraction. SOCcrop (SOC derived from crops contents in the light and heavy fractions in poplar plantations were significantly lower as compared with SOC contents in croplands, but tree-derived C in bulk soil, light and heavy fraction pools increased gradually with increasing stand basal area after afforestation. Our study indicated that cropland afforestation could sequester new C derived from trees into surface mineral soil, but did not enhance the stability of SOC due to a fast turnover of SOC in this semi-arid region.

  6. Seroepidemiological survey on Leptospira spp. infection in wild and domestic mammals in two distinct areas of the semi-arid region of northeastern Brazil. (United States)

    Dos Santos, Laís Ferrari; Guimarães, Maíra Freitas; de Souza, Gisele Oliveira; da Silva, Ivo Wesley Gomes; Santos, Josenilton Rodrigues; Azevedo, Sérgio Santos; Labruna, Marcelo Bahia; Heinemann, Marcos Bryan; Horta, Mauricio Claudio


    Leptospirosis is a bacterial zoonotic disease that causes severe reproductive problems in livestock and generates economic losses for farmers. This study aimed to determine the seroprevalence of anti-Leptospira antibodies in small mammals, both wild and domestic, in two distinct areas of the semi-arid region of northeastern Brazil: the National Park of Serra das Confusões (NPSC), state of Piauí, a preserved area; and rural areas in the municipalities of Petrolina and Lagoa Grande, state of Pernambuco, non-preserved areas. Serum samples were evaluated using the microscopic agglutination test (MAT). Approximately 4% (6/152) of the wild animals were positive, all of them in the non-preserved area. Overall, the seroprevalence rates among goats and sheep were 13.4 (77/576) and 4.6% (24/518), respectively, confirmed in both areas. The seroprevalence rates in dogs and cats were 5.6 (10/180) and 4.7% (2/43) and were determined only in the non-preserved area. The risk factors associated with Leptospira spp. infection were as follows: ages of 1-3 and > 3 years for goats and sheep, region (preserved area) for goats, intensive management system for sheep, and region (non-preserved area) for dogs and wildlife. The present study confirmed the presence of circulation of Leptospira spp. in both of these areas of the Caatinga biome, as well as a variety of serotypes in these areas.

  7. Screening of efficient arbuscular mycorrhizal fungi for Azadirachta indica under nursery condition: a step towards afforestation of semi-arid region of western India

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    K. Banerjee


    Full Text Available To optimize nursery practices for efficient plant production procedures and to keep up to the ever growing demand of seedlings, identification of the most suitable species of arbuscular mycorrhizal fungi (AMF, specific for a given tree species, is clearly a necessary task. Sixty days old seedlings of Neem (Azadirachta indica A. Juss raised in root trainers were inoculated with six species of AMF and a mixed inoculum (consortia and kept in green house. Performances of the treatments on this tree species were evaluated in terms of growth parameters like plant height shoot collar diameter, biomass and phosphorous uptake capabilities. Significant and varied increase in the growth parameters and phosphorous uptake was observed for most of the AMF species against control. Consortia culture was found to be the best suited AMF treatment for A.indica, while Glomus intraradices and Glomus mosseae were the best performing single species cultures. It is the first time in the state of Gujarat that a wide variety of AMF species, isolated from the typical semi-arid region of western India, were tested for the best growth performance with one of the most important tree species for the concerned region.

  8. Screening of efficient arbuscular mycorrhizal fungi for Azadirachta indica under nursery condition: a step towards afforestation of semi-arid region of western India. (United States)

    Banerjee, K; Gadani, M H; Srivastava, K K; Verma, Neelam; Jasrai, Y T; Jain, N K


    To optimize nursery practices for efficient plant production procedures and to keep up to the ever growing demand of seedlings, identification of the most suitable species of arbuscular mycorrhizal fungi (AMF), specific for a given tree species, is clearly a necessary task. Sixty days old seedlings of Neem (Azadirachta indica A. Juss) raised in root trainers were inoculated with six species of AMF and a mixed inoculum (consortia) and kept in green house. Performances of the treatments on this tree species were evaluated in terms of growth parameters like plant height shoot collar diameter, biomass and phosphorous uptake capabilities. Significant and varied increase in the growth parameters and phosphorous uptake was observed for most of the AMF species against control. Consortia culture was found to be the best suited AMF treatment for A. indica, while Glomus intraradices and Glomus mosseae were the best performing single species cultures. It is the first time in the state of Gujarat that a wide variety of AMF species, isolated from the typical semi-arid region of western India, were tested for the best growth performance with one of the most important tree species for the concerned region.

  9. Religiousness/spirituality do not necessarily matter: Effect on risk perception and adaptive strategies in the semi-arid region of NE Brazil

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    Regina Célia da Silva Oliveira


    Full Text Available The impact of environmental changes is a major threat to livelihoods, especially for small farmers in semi-arid regions. Therefore, local communities undertake efforts to cope with these new environmental conditions and researchers try to understand the limits of possible adaptive strategies. Religiousness/spirituality are two important factors that can influence environmental awareness and adaptive responses to risks caused by natural phenomena. However, studies addressing the relationship between such factors are either scarce or based on anecdotal information. This article discusses the influence of religiousness/spirituality on the perception of environmental risks by farmers in a rural community in Brazil's northeast region, and their knowledge of adaptive strategies to deal with such concerns. Religiousness/spirituality can positively or negatively influence the perception of risk and knowledge of adaptive strategies when facing environmental uncertainty. We note that dimensions of religiousness/spirituality such as religious history, values/beliefs, commitment, and daily spiritual experiences influence wealth and the sharing of natural perceived risks, as well as adaptive strategies. Based on our results, we conclude that religiousness/spirituality dimensions exert both positive and negative effects on the perception of environmental risks and ways of coping with the impacts of rapid environmental changes.

  10. Diversity and structure of microcrustacean assemblages (Cladocera and Copepoda and limnological variability in perennial and intermittent pools in a semi-arid region, Bahia, Brazil

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    Nadson R. Simões


    Full Text Available Temporary wetlands undergo recurrent drought due to the scarcity of water, which disrupts the hydrological connectivity with adjacent aquatic systems. However, some environments retain water for longer periods, allowing greater persistence of the community. The current study evaluated differences in the microcrustacean assemblages and limnological variability between perennial and intermittent pools in a semi-arid region of Brazil. The abiotic features (water temperature, pH, total alkalinity, electrical conductivity and depth of intermittent pools were affected more than perennial pools due to loss of water volume. This may have contributed to a higher average richness and diversity index in some intermittent pools and differences in the structure of the assemblages. The lowest species richness and diversity were recorded where physical factors, such as a large quantity of suspended solids and variability in the electrical conductivity of the water and pH, make the environment unsuitable for these organisms. These results suggest that community development in intermittent pools is interrupted by the dry season; when the water returns, due to rainfall or rising groundwater, each pond undergoes a different process of colonization. In these circumstances, the biological importance of temporary aquatic environments is clear, since such pools provide shelters and have an important role in the maintenance of the regional diversity of aquatic environments.

  11. Genotypic and symbiotic diversity of Rhizobium populations associated with cultivated lentil and pea in sub-humid and semi-arid regions of Eastern Algeria. (United States)

    Riah, Nassira; Béna, Gilles; Djekoun, Abdelhamid; Heulin, Karine; de Lajudie, Philippe; Laguerre, Gisèle


    The genetic structure of rhizobia nodulating pea and lentil in Algeria, Northern Africa was determined. A total of 237 isolates were obtained from root nodules collected on lentil (Lens culinaris), proteaginous and forage pea (Pisum sativum) growing in two eco-climatic zones, sub-humid and semi-arid, in Eastern Algeria. They were characterised by PCR-restriction fragment length polymorphism (RFLP) of the 16S-23S rRNA intergenic region (IGS), and the nodD-F symbiotic region. The combination of these haplotypes allowed the isolates to be clustered into 26 distinct genotypes, and all isolates were classified as Rhizobium leguminosarum. Symbiotic marker variation (nodD-F) was low but with the predominance of one nod haplotype (g), which had been recovered previously at a high frequency in Europe. Sequence analysis of the IGS further confirmed its high variability in the studied strains. An AMOVA analysis showed highly significant differentiation in the IGS haplotype distribution between populations from both eco-climatic zones. This differentiation was reflected by differences in dominant genotype frequencies. Conversely, no host plant effect was detected. The nodD gene sequence-based phylogeny suggested that symbiotic gene diversity in pea and lentil nodulating rhizobial populations in Algeria was low compared to that reported elsewhere in the world. Copyright © 2014 Elsevier GmbH. All rights reserved.

  12. Estratégias na suplementação de vacas leiteiras no semi-árido do Brasil Strategies for the supplementation of dairy cows in the Brazilian semi-arid

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    Marcelo de Andrade Ferreira


    Full Text Available A região semi-árida do Brasil prolonga-se por uma área de 928 km² abrangendo uma parte do norte dos estados de Minas Gerais e Espírito Santo, os sertões da Bahia, Sergipe, Alagoas, Pernambuco, Paraíba, Rio Grande do Norte, Ceará e Piauí e mais 45 municípios do sudeste do Maranhão. A população é predominantemente rural e a ocupação principal de sua força de trabalho é a agropecuária. A pecuária leiteira aparece como uma das poucas opções nas regiões semi-áridas, principalmente no nordeste do Brasil, onde a alimentação dos rebanhos fundamenta-se na utilização de forrageiras cultivadas e no uso da vegetação nativa, predominantemente a caatinga, aspecto que imprime características estacionais à produção nesta região. A escassez e irregularidade acentuada na distribuição de chuvas, tanto no tempo quanto no espaço, com a ocorrência de longos períodos de estiagem, praticamente, determina a obrigatoriedade de suplementação de vacas leiteiras nos sistemas de produções em regiões semi-áridas do Brasil.Desta forma, a suplementação tem se baseado na utilização de recursos forrageiros adaptados à seca, co- produtos e resíduos da agroindústria local e em alimentos concentrados. Algumas alternativas têm sido utilizadas pelos produtores na tentativa de reduzir custos sem perder produtividade nos períodos de estiagem. Para superar as adversidades alguns sistemas de produção têm sido propostos como o CBL (Caatinga-buffel-leucena e o Sistema Glória. Além desses sistemas mencionados anteriormente, merecem destaque a utilização de co-produtos agroindustriais, restos de cultura, além de forrageiras nativas e adaptadas. Neste aspecto, a palma forrageira (Opuntia fícus indica- Mill merece atenção especial pela sua grande adaptação, valor nutritivo e produtividade.The Brazilian semi-arid region has 928 km² ranging from the northern portion of Minas Gerais and Espirito Santo States, the semi-arid lands

  13. Spatial and temporal analysis of the drought vulnerability and risks over eight decades in a semi-arid region (Tensift basin: Morocco) (United States)

    Fniguire, Fatima; Laftouhi, Nour-Eddine; Saidi, Mohamed Elmehdi; Zamrane, Zineb; El Himer, Hicham; Khalil, Nourddine


    In the last few decades, drought has become a chronic phenomenon in Morocco. It began at the end of the 1970s and continued to the late 2000s. In the present study, hydrometeorological data sets, Standardized Precipitation Index method, and non-parametric tests were used to recognize the frequency and the severity of drought events during the period between 1929 and 2010. The Standardized Precipitation Index showed significant inter-annual fluctuation and evolution of rainfall amounts representing wet cycles (i.e., before 1975) followed by a long period of drought between 1975 and 2004. The inter-annual variability of rainfall is accompanied by shifts of stationarity in the rainfall series. The statistical test of Pettitt, Bayesian method of Lee and Heghinian, Buishand procedure, and Hubert test revealed shifts around the mid 70s. After this period, a deficit of rainfall (with a maximum value of -30 %) was registered. The probabilities of monthly Standardized Precipitation Index values were normal to below normal during the last 40 years. In fact, the increase of drought risk may be resulted from the increase of frequency and severity of meteorological drought. The proposed Standardized Precipitation Index method and non-parametric tests yielded reasonable and satisfactory results for Morocco. Therefore, this approach could be successfully applied to other semi-arid, dry, sub-humid, or semi-humid regions worldwide, where rainfall series are showing high seasonality and year-to-year variability.

  14. Regional and local influence of grazing activity on the diversity of a semi-arid dung beetle community

    DEFF Research Database (Denmark)

    Lobo, Jorge M.; Hortal, Joaquín; Cabrero-Sañudo, Francisco J.


    This study analyses the effect of resource availability (i.e. sheep dung) on dung beetle communities in an arid region of Central Spain, both at regional and at local scales. A total of 18 sites within 600 km2 were sampled for the regional analysis and 16 sites within the 30 km2 of an Iberian mun...

  15. Rivers through time: historical changes in the riparian vegetation of the semi-arid, winter rainfall region of South Africa in response to climate and land use. (United States)

    Hoffman, M Timm; Rohde, Richard Frederick


    This paper examines how the riparian vegetation of perennial and ephemeral rivers systems in the semi-arid, winter rainfall region of South Africa has changed over time. Using an environmental history approach we assess the extent of change in plant cover at 32 sites using repeat photographs that cover a time span of 36-113 years. The results indicate that in the majority of sites there has been a significant increase in cover of riparian vegetation in both the channel beds and adjacent floodplain environments. The most important species to have increased in cover across the region is Acacia karroo. We interpret the findings in the context of historical changes in climate and land use practices. Damage to riparian vegetation caused by mega-herbivores probably ceased sometime during the early 19th century as did scouring events related to large floods that occurred at regular intervals from the 15th to early 20th centuries. Extensive cutting of riparian vegetation for charcoal and firewood has also declined over the last 150 years. Changes in the grazing history as well as increased abstraction and dam building along perennial rivers in the region also account for some of the changes observed in riparian vegetation during the second half of the 20th century. Predictions of climate change related to global warming anticipate increased drought events with the subsequent loss of species and habitats in the study area. The evidence presented here suggests that an awareness of the region's historical ecology should be considered more carefully in the modelling and formulation of future climate change predictions as well as in the understanding of climate change impacts over time frames of decades and centuries.

  16. Evaluation of two empirical wind erosion models in arid and semi-arid regions of China and the USA (United States)

    The Tarim Basin in China and Columbia Plateau in the USA are important agricultural regions as well as source regions of windblown dust that impact air quality in Asia and North America. Wind erosion models are important tools for assessing the potential erodibility of soils and best management prac...

  17. Bi-decadal groundwater level trends in a semi-arid south indian region: Declines, causes and management

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    Rajendra P. Sishodia


    New hydrological insights for the region: Contrary to common perception of widespread groundwater declines only 22–36% of the wells showed statistically significant declines. The use of well depth during dry well periods may slightly underestimate the number of declining wells (by 1% and rate of decline. Increase in groundwater irrigated area combined with rainfall and power subsidy policy, were the main causative factors for the decline. Groundwater decline after implementation of free-electricity policy in 2004 confirmed the nexus between power subsidy and groundwater. These declines are likely to worsen due to future well drillings. Trends in other regions with similar hydro-geologic conditions need to be analyzed to verify groundwater declines and its linkages with power subsidy. Once established, reforms in power subsidy and well permit policy along with conversion to efficient micro–irrigation may be needed to maintain or enhance groundwater availability in the crystalline aquifer region of India (240 million ha.

  18. Temporal and elevation trends in rainfall erosivity on a 149 km2 watershed in a semi-arid region of the American Southwest

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    Mark A. Nearing


    Full Text Available Temporal changes in rainfall erosivity can be expected to occur with changing climate, and because rainfall amounts are known to be in part of a function of elevation, erosivity can be expected to be influenced by elevation as well. This is particularly true in mountainous regions such as are found over much of the western United States. The objective of this study was to identify temporal and elevation trends in rainfall erosivity on a 149 km2 (58 miles2 watershed in a semi-arid region of southeastern Arizona. Data from 84 rain gages for the years 1960–2012 at elevations ranging from 1231 to 1644 m (4038–5394 ft were used in the analyses. The average annual erosivity over the watershed as a whole was 1104 MJ mm ha−1 h−1 yr−1 (65 hundreds of foot ton inch acre−1 h−1 yr−1, and ranged from approximately 950 to 1225 MJ mm ha−1 h−1 yr−1 (56–72 hundreds of foot ton inch acre−1 h−1 yr−1, with a statistical trend showing greater erosivity at the higher elevations. No statistically significant temporal changes in annual or summer erosivities were found. This result stands in contrast to recent modeling studies of runoff and erosion in the area based on downscaled GCM information that project significant levels of erosivity changes over coming decades. These results are consistent with known orographic rainfall effects, but contrast with recent studies that presented projections of significant trends of increasing erosivity in the future based on downscaled GCM outputs for the area. The results illustrate the need for testing and developing improved techniques to evaluate future erosion scenarios for purposes of making targeted soil conservation decisions.

  19. Achieve a Better Understanding of Cloud and Precipitation Processes for the Promotion of Water Security in Arid and Semi-Arid Regions (United States)

    Farrah, S.; Al Yazidi, O.


    has been recently replaced by a new drive to solve the technical obstacles impeding its potential. There is now a real prospect that this science will come of age and play its rightful part in boosting sustainable water supplies for people at risk in arid and semi-arid regions of the world.

  20. Detection and differentiation of pollution in urban surface soils using magnetic properties in arid and semi-arid regions of northwestern China. (United States)

    Wang, Bo; Xia, Dunsheng; Yu, Ye; Jia, Jia; Xu, Shujing


    Increasing urbanization and industrialization over the world has caused many social and environmental problems, one of which drawing particular concern is the soil pollution and its ecological degradation. In this study, the efficiency of magnetic methods for detecting and discriminating contaminates in the arid and semi-arid regions of northwestern China was investigated. Topsoil samples from six typical cities (i.e. Karamay, Urumqi, Lanzhou, Yinchuan, Shizuishan and Wuhai) were collected and a systematic analysis of their magnetic properties was conducted. Results indicate that the topsoil samples from the six cities were all dominated by coarse low-coercivity magnetite. In addition, the average magnetite contents in the soils from Urumqi and Lanzhou were shown to be much higher than those from Karamay, Yinchuan, Shizuishan and Wuhai, and they also have relatively higher χlf and χfd% when compared with cities in eastern China. Moreover, specific and distinctive soil pollution signals were identified at each sampling site using the combined various magnetic data, reflecting distinct sources. Industrial and traffic-derived pollution was dominant in Urumqi and Lanzhou, in Yinchuan industrial progress was observed to be important with some places affected by vehicle emission, while Karamay, Shizuishan and Wuhai were relatively clean. The magnetic properties of these latter three cities are significantly affected by both anthropogenic pollution and local parent materials from the nearby Gobi desert. The differences in magnetic properties of topsoil samples affected by mixed industrial and simplex traffic emissions are not obvious, but significant differences exist in samples affected by simplex industrial/vehicle emissions and domestic pollution. The combined magnetic analyses thus provide a sensitive and powerful tool for classifying samples according to likely sources, and may even provide a valuable diagnostic tool for discriminating among different cities

  1. Managing Environmental Flows for Impounded Rivers in Semi-Arid Regions- A Habitat Suitability Index (HSI) Approach for the Assessment of River Habitat for Salmonid Populations (United States)

    Pai, H.; Sivakumaran, K.; Villamizar, S. R.; Flanagan, J.; Guo, Q.; Harmon, T. C.


    Balancing ecosystem health in water-scarce, agriculturally dominated river basins remains a challenge. In dry water years, maintaining conditions for restored and sustained indigenous fish populations (a frequently used indicator for ecosystem health) is particularly challenging. Competing human demands include urban and agricultural water supplies, hydropower, and flood control. In many semi-arid regions, increasing drought intensity and frequency under future climate scenarios will combine with population increases to water scarcity. The goal of this work is to better understand how reservoir releases affect fish habitat and overall river aquatic ecosystem quality. Models integrating a diverse array of physical and biological processes and system state are used to forecast the river ecosystem response to changing drivers. We propose a distributed parameter-based Habitat Suitability Index (HSI) approach for assessing fish habitat quality. Our river ecosystem HSI maps are based on a combination of the following: (1) In situ data describing stream flow and water quality conditions; (2) Spatial observations, including surveyed cross-sections, aerial imagery and digital elevation maps (DEM) of the river and its riparian corridor; and (3) Simulated spatially distributed water depths, flow velocities, and temperatures estimated from 1D and 2D river flow and temperature models (HEC-RAS and CE-QUAL-W2, respectively). With respect to (2), image processing schemes are used to classify and map key habitat features, namely riparian edge and shallow underwater vegetation. HSI maps can be modified temporally to address specific life cycle requirements of indicator fish species. Results are presented for several reaches associated with the San Joaquin River Restoration Project, focusing on several components of the Chinook salmon life cycle. HSI maps and interpretations are presented in the context of a range of prescribed reservoir release hydrographs linked to California water

  2. Managing forests, water resources and their interaction in the face of increasing drought frequency and severity in semi-arid regions. (United States)

    Tague, C.; Moritz, M.


    Drought and in particular high-temperature droughts are increasingly a concern in semi-arid climates through the globe. Within these regions both forest health and water resources are highly sensitive to the severity and frequency of drought. Drought conditions reduce streamflow, but also water availability and in the case of high temperature drought, water demand for terrestrial ecosystems. Hydrologic and ecosystem responses are coupled since changes in water use by terrestrial ecosystems can in turn influence the impact of drought on downslope streamflow. Further the impact of drought on forest structure, via declines in productivity, increases in fire and mortality and ultimately species change can have longer-term impacts on streamflow, even after precipitation and temperature regimes return to more normal conditions. We argue that accounting for multi-year and coupled ecohydrologic post-drought impacts is an important component of assessing ecosystem health and water resource impacts of droughts in a changing climate. A multi-year, coupled perspective is also important for the strategic allocation of forest management practices, including fuel treatments that may be targeted for reducing the impact of droughts. We utilize a coupled eco-hydrologic model, combined with field measurements from the Sierra Critical Zone Observatory and elsewhere to show how forest structural changes can be a dominant control on streamflow responses, particularly in years following drought and show how forest management practices can interact with drought vulnerability in sometimes surprising ways. We conclude by presenting an approach for rapid assessment of location specific drought vulnerability and management impacts that takes these interactions into account.

  3. Combining hydrology and mosquito population models to identify the drivers of Rift Valley fever emergence in semi-arid regions of West Africa.

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    Valérie Soti

    Full Text Available BACKGROUND: Rift Valley fever (RVF is a vector-borne viral zoonosis of increasing global importance. RVF virus (RVFV is transmitted either through exposure to infected animals or through bites from different species of infected mosquitoes, mainly of Aedes and Culex genera. These mosquitoes are very sensitive to environmental conditions, which may determine their presence, biology, and abundance. In East Africa, RVF outbreaks are known to be closely associated with heavy rainfall events, unlike in the semi-arid regions of West Africa where the drivers of RVF emergence remain poorly understood. The assumed importance of temporary ponds and rainfall temporal distribution therefore needs to be investigated. METHODOLOGY/PRINCIPAL FINDINGS: A hydrological model is combined with a mosquito population model to predict the abundance of the two main mosquito species (Aedes vexans and Culex poicilipes involved in RVFV transmission in Senegal. The study area is an agropastoral zone located in the Ferlo Valley, characterized by a dense network of temporary water ponds which constitute mosquito breeding sites. The hydrological model uses daily rainfall as input to simulate variations of pond surface areas. The mosquito population model is mechanistic, considers both aquatic and adult stages and is driven by pond dynamics. Once validated using hydrological and entomological field data, the model was used to simulate the abundance dynamics of the two mosquito species over a 43-year period (1961-2003. We analysed the predicted dynamics of mosquito populations with regards to the years of main outbreaks. The results showed that the main RVF outbreaks occurred during years with simultaneous high abundances of both species. CONCLUSION/SIGNIFICANCE: Our study provides for the first time a mechanistic insight on RVFV transmission in West Africa. It highlights the complementary roles of Aedes vexans and Culex poicilipes mosquitoes in virus transmission, and recommends

  4. Reservoir inflow forecasting with a modified coactive neuro-fuzzy inference system: a case study for a semi-arid region (United States)

    Allawi, Mohammed Falah; Jaafar, Othman; Mohamad Hamzah, Firdaus; Mohd, Nuruol Syuhadaa; Deo, Ravinesh C.; El-Shafie, Ahmed


    Existing forecast models applied for reservoir inflow forecasting encounter several drawbacks, due to the difficulty of the underlying mathematical procedures being to cope with and to mimic the naturalization and stochasticity of the inflow data patterns. In this study, appropriate adjustments to the conventional coactive neuro-fuzzy inference system (CANFIS) method are proposed to improve the mathematical procedure, thus enabling a better detection of the high nonlinearity patterns found in the reservoir inflow training data. This modification includes the updating of the back propagation algorithm, leading to a consequent update of the membership rules and the induction of the centre-weighted set rather than the global weighted set used in feature extraction. The modification also aids in constructing an integrated model that is able to not only detect the nonlinearity in the training data but also the wide range of features within the training data records used to simulate the forecasting model. To demonstrate the model's efficacy, the proposed CANFIS method has been applied to forecast monthly inflow data at Aswan High Dam (AHD), located in southern Egypt. Comparative analyses of the forecasting skill of the modified CANFIS and the conventional ANFIS model are carried out with statistical score indicators to assess the reliability of the developed method. The statistical metrics support the better performance of the developed CANFIS model, which significantly outperforms the ANFIS model to attain a low relative error value (23%), mean absolute error (1.4 BCM month-1), root mean square error (1.14 BCM month-1), and a relative large coefficient of determination (0.94). The present study ascertains the better utility of the modified CANFIS model in respect to the traditional ANFIS model applied in reservoir inflow forecasting for a semi-arid region.

  5. Analysis of drought events in a Mediterranean semi-arid region, Using SPOT-VGT and TERRA-MODIS satellite products (United States)

    Zribi, Mehrez; Dridi, Ghofrane; Amri, Rim; Lili-Chabaane, Zohra


    In semi-arid regions, and northern Africa in particular, the scarcity of rainfall and the occurrence of long periods of drought, represent one of the main environmental factors having a negative effect on agricultural productivity. This is the case in Central Tunisia, where the monitoring of agricultural and water resources is of prime importance. Vegetation cover is a key parameter to analyse this problem. Remote sensing has shown in the last decades a high potential to estimate these surface parameters. This study is based on two satellite products: SPOT-VGT (1998-2012) and TERRA-MODIS (2001-2012) NDVI products. They are used to study the dynamics of vegetation and land use. Different behaviors linked to drought periods have been observed. A strong agreement is observed between products proposed by the two sensors. Low spatial resolution SPOT-VGT and TERRA-MODIS NDVI images were used to map the land into three characteristic classes: olive trees, annual agriculture and pastures. An analysis of vegetation behaviour for dry years is proposed using the Windowed Fourier Transform (WTF). The Fourier Transform is able to analyze the frequency content of a signal in the time domain by decomposing the signal as the superposition of sine and cosine basis functions. Analysis for annual agricultural areas demonstrates a combined effect between climate and farmers behaviours. In these areas, bare soils show a high increasing for drought years. Highest percent of bare soil is retrieved with TERRA-MODIS than with SPOT-VGT. This could be explained by the spatial resolution of the two sensors. The temporal series of optical images are finally used to calculate a drought index, namely the VAI (Vegetation Anomaly Index), on the plain of Kairouan (Amri et al., 2011). This index shows a high correlation with precipitation statistics.

  6. Species Specific Drought Stress and Temperature Induced Growth Decline in Semi-arid Region of Trans-Himalaya in Central Nepal (United States)

    Tiwari, A.; Zhe-Kun, Z.


    Investigations of growth-climate relationships are important to understand the response of forest growth and the dendroclimatic reconstructions (Briffa et al., 1998a; Tessier et al., 1997). This also provides crucial information to assess future forest productivity, growth performance, vegetation dynamics and tree species distributions (Thuiller et al., 2005; Tardif et al., 2006). We explored growth climate response of Abies spectabilis, Betula utilis and Picea smithiana at different elevations of same mountain slope from the semi-arid trans-Himalayan zone of central Himalaya (Mustang, Nepal) in order to observe their drought tolerance. The ring width indices were correlated with the instrumental data (1970-2013 AD) from the nearest climate station to observe the growth climate response. Spring season (March-May) moisture was found to be highly critical for radial growth in all species. Further, we compared the basal area increment (BAI) trend among different species as BAI is the strong indicator of growth trend over the conventional detrended tree ring width indices. Our results demonstrated that BAI is rapidly declining for Betula utilis among three species irrespective of being distributed comparatively to the moist region in the mountain indicating that drought tolerance is highly species specific, as an early warning signal of climate change. Since the global climate models disagree on predicting precipitation intensity and seasonality in the coming decades, and more extreme precipitation events are likely worldwide (IPCC 2013), the least drought tolerant species like birch would be threatened to their survival and might decline due to warming induced drought stress which is already seen with rapid growth decline in the recent decades.

  7. An analytical framework for extracting hydrological information from time series of small reservoirs in a semi-arid region (United States)

    Annor, Frank; van de Giesen, Nick; Bogaard, Thom; Eilander, Dirk


    small reservoirs in the Upper East Region of Ghana. Reservoirs without obvious large seepage losses (field survey) were selected. To verify this, stable water isotopic samples are collected from groundwater upstream and downstream from the reservoir. By looking at possible enrichment of downstream groundwater, a good estimate of seepage can be made in addition to estimates on evaporation. We estimated the evaporative losses and compared those with field measurements using eddy correlation measurements. Lastly, we determined the cumulative surface runoff curves for the small reservoirs .We will present this analytical framework for extracting hydrological information from time series of small reservoirs and show the first results for our study region of northern Ghana.

  8. Spatial variability of air temperature in a free-stall in the Northeastern semi-arid region of Brazil

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    Indira C. M. Gonçalves


    Full Text Available ABSTRACT The knowledge on the spatial variability of climatic attributes and the building of Kriging maps can assist in the design and management of confined animal facilities, by allowing a spatial visualization that is helpful for the planning and control of information from the production environment. The study aimed to characterize the spatial variability of air temperature in a free-stall barn used for dairy cattle confinement located in Petrolina-PE, Brazil, in different seasons and at different times. The variable air temperature was recorded at 136 points distributed in the areas under the shed and the shade cloth for the study of spatial variability and the construction of maps by Kriging. Air temperature data was collected in the winter and in the summer, in the months of July and August (2013 and January and February (2014, at different times (9 and 15 h. According to the results, the use of geostatistics enabled to define areas with different spatial variabilities in air temperature and specific areas in the free-stall with values higher than the recommended levels for thermal comfort. In addition, the central part of the facility is the region with the lowest values of air temperatures, due to the presence of a ridge vent.

  9. The role of economic analysis in groundwater management in semi-arid regions: the case of Nigeria (United States)

    Acharya, Gayatri

    The aim of this paper is to use an economic framework to derive decision making rules for river basin management with a focus on groundwater resources. Using an example from northern Nigeria, the paper provides an example of how decision making for sustainable water resources management may be facilitated by comparing net benefits and costs across a river basin. It is argued that economic tools can be used to assess the value of water resources in different uses, identify and analyze management scenarios, and provide decision rules for the sustainable use and management of surface and ground water resources in the region. L'objet de cet article est l'utilisation d'un cadre économique pour établir des règles de prise de décision pour la gestion d'un bassin versant prenant en compte les ressources en eau souterraine. À partir d'un exemple du Nigéria septentrional, cet article explique comment une prise de décision pour la gestion durable de ressources en eau peut être facilitée en comparant les bénéfices nets et les coûts sur tout le bassin versant. Il est montré que les outils économiques peuvent être utilisés pour établir la valeur des ressources en eau dans les différents usages, pour identifier et analyser des scénarios de gestion et pour fournir des règles de décision pour un usage et une gestion durables des ressources en eaux de surface et souterraines dans la région. El objetivo de este artículo es utilizar un enfoque económico para deducir reglas de toma de decisión en la gestión de cuencas, haciendo énfasis en los recursos subterráneos. Por medio de un ejemplo del Norte de Nigeria, se ilustra cómo la toma de decisiones orientadas a la gestión sustentable de los recursos hídricos puede ser facilitada si se compara los beneficios netos y los costes en toda la cuenca. Se argumenta que las herramientas económicas pueden servir para establecer el valor de los recursos hídricos destinados a usos diferentes, para identificar y

  10. Ele não quer com camisinha e eu quero me prevenir: exposição de adolescentes do sexo feminino às DST/aids no semi-árido nordestino He does not want it with condom and I want to protect myself: exposure of female adolescents to STD/AIDS in the semi-arid region of the Brazilian northeast

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    Juliana Sampaio


    semi-arid region located in the Northeast of Brazil. The applied methodology was supported by the qualitative approach in health, and Discursive Practices and Production of Meaning (Spink, 2004; Medrado and Spink, 1999 were used as the theoretical and methodological model. Three methodological strategies were used for data collection: 1,024 hours of participant observation, 72 semi-structured interviews and 36 focus groups, comprising two groups of actors: 72 professionals of 8 health teams and 360 adolescents of both sexes. From the analysis of results it was possible to verify that the Northeastern reality is permeated by characteristics that make the women vulnerable to STD / AIDS, such as: a low educational levels; b unequal gender relations; c absence of a prevention policy targeted at teenagers; d lack of bonds between health professionals and the population; e the frequent understanding of health services as a space exclusively for women. In light of this context, we point to the need of policies of integral health care to adolescents that approach the sexual and reproductive rights in a gender perspective for the effective prevention of STD / AIDS, exerting a direct impact on improving the quality of their lives.

  11. Proposal for regional sustainable development in semi-arid promoted by agents of the electric sector; Proposta de desenvolvimento regional sustentavel no semi-arido promovido por agente do setor eletrico

    Energy Technology Data Exchange (ETDEWEB)

    Polizel, L.H.; Tahan, C.M.V.; Pelegrini, M.A.; Soares, B.F. [Universidade de Sao Paulo (ENERQ/USP), SP (Brazil). Centro de Estudo em Regulacao e Qualidade de Energia; Takeno, H.K. [Companhia Energetica de Petrolina (CEP), PE (Brazil); Silva, O.C. da; Monteiro, B.; Velazquez, S.M.S.G. [Universidade de Sao Paulo (CENBIO/USP), SP (Brazil). Centro Nacional de Referencia em Biomassa; Drumond, M.A.


    This paper shows a thoroughly analysis of a biodiesel production model tailored to insert in the production chain communities near fossil fuels fired power plants located in the northeast Brazilian semi-arid. Such insertion would be conduced by the replacement of diesel by a diesel-bio diesel mixture, the last produced by local families. Among the factors analyzed on this small scale bio diesel production chain are: the castor oil extraction, transesterification process, efficiency and adequacy in power plants. The aim is to turn thermal power plants into a sustainable development vector, considering social, economical and environmental aspects such as local employment and income boost, settlement increase on rural areas, decrease of green house gases emissions, clean energy production and so forth. (author)

  12. [Effects of climate warming on oil flax growth and water use efficiency in semi-arid region of Loess Plateau, Northwest China]. (United States)

    Yao, Yu-bi; Wang, Run-yuan; Yang, Jin-hu; Xiao, Guo-ju; Zhang, Xiu-yun; Yue, Ping


    By using the site-specific observation data of oil flax growth and related meteorological records in semi-arid region of Loess Plateau, this paper studied the effects of climate change on the oil flax growth, and analyzed the relationships between the oil flax water use efficiency and meteorological condition. In this region, the annual precipitation displayed a decreasing trend, and its climatic trend rate was -15.80 mm (10 a)(-1), with an annual periodic change of 3 a and 6 a, whereas the annual air temperature had an increasing trend, and its climatic trend rate was 0.36 degrees C (10 a)(-1). In crop growth period, the aridity index displayed a marked increasing trend, its climatic trend rate was 0.12 (10 a)(-1), and the aridity tendency was more obvious from the beginning of 1990s to the year 2009. From sowing to maturation, oil flax needed 120-150 d, 1700-2100 degrees C d of > or = 0 degrees C accumulated temperature, 200-250 mm precipitation, and 1000-1300 h sunshine hours. The main meteorological factors affecting the oil flax growth in the region were air temperature and precipitation. The increase of air temperature shortened the prophase vegetative growth stage, whereas the increase of air temperature and the decrease of precipitation extended the reproductive growth stage, causing the extension of the whole growth period of the oil flax. The air temperature in the oil flax whole growth period except at seeding stage and maturing stage had negative effect on the yield formation, being more obvious at squaring stage, whereas the precipitation in the whole growth period except at blooming stage had positive effect on the yield formation, being more obvious at seeding stage. The water use efficiency of the oil flax was significantly positively correlated with the air temperature and sunshine hours at seeding stage as well as the aridity index from squaring stage to maturing stage, and negatively correlated with the precipitation from squaring stage to

  13. Evaluation of Three Evaporation Estimation Techniques In A Semi-Arid Region (Omar El Mukhtar Reservoir Sluge, Libya- As a case Study

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    Lubna s. Ben Taher


    Full Text Available In many semi-arid countries in the world like Libya, drinking water supply is dependent on reservoirs water storage. Since the evaporation rate is very high in semi-arid countries, estimates and forecasts of reservoir evaporation rate can be useful in the management of major water source. Many researchers have been investigating the suitability of estimates evaporation rates methods in many climatic settings, infrequently of which were in an arid setting. This paper presents the modeling results of evaporation from Omar El Mukhtar Reservoir, Libya. Three techniques namely (artificial neural networks (ANN, Multiple linear regression (MLR and response surface methods (RSM were developed, to assess the estimation of monthly evaporation records from 2001 to 2009; their relative performance were compared using the coefficient of determination(E, mean absolute percentage error (MAPE%, and 95% confidence interval. The key variables used to develop and validate the models were: monthly (precipitation Rf., average temperature Temp., relative humidity Rh., sunshine hours Sh., atmospheric pressure Pa. and wind speed Ws.. The encouraging results approved that the models with more inputs generally had better accuracies and the ANN model performed superior to the other models in predicting monthly Evp with high E=0.86 and low MAPE%= 13.9 and the predicted mean within the range of observed 95CI%. In summary, it is revealed in this study that the ANN and RSM models are appropriate for predicting Evp using climatic inputs in semi-arid climate.

  14. Improving estimates of water resources in a semi-arid region by assimilating GRACE data into the PCR-GLOBWB hydrological model (United States)

    Tangdamrongsub, Natthachet; Steele-Dunne, Susan C.; Gunter, Brian C.; Ditmar, Pavel G.; Sutanudjaja, Edwin H.; Sun, Yu; Xia, Ting; Wang, Zhongjing


    An accurate estimation of water resources dynamics is crucial for proper management of both agriculture and the local ecology, particularly in semi-arid regions. Imperfections in model physics, uncertainties in model land parameters and meteorological data, as well as the human impact on land changes often limit the accuracy of hydrological models in estimating water storages. To mitigate this problem, this study investigated the assimilation of terrestrial water storage variation (TWSV) estimates derived from the Gravity Recovery And Climate Experiment (GRACE) data using an ensemble Kalman filter (EnKF) approach. The region considered was the Hexi Corridor in northern China. The hydrological model used for the analysis was PCR-GLOBWB, driven by satellite-based forcing data from April 2002 to December 2010. The impact of the GRACE data assimilation (DA) scheme was evaluated in terms of the TWSV, as well as the variation of individual hydrological storage estimates. The capability of GRACE DA to adjust the storage level was apparent not only for the entire TWSV but also for the groundwater component. In this study, spatially correlated errors in GRACE data were taken into account, utilizing the full error variance-covariance matrices provided as a part of the GRACE data product. The benefits of this approach were demonstrated by comparing the EnKF results obtained with and without taking into account error correlations. The results were validated against in situ groundwater data from five well sites. On average, the experiments showed that GRACE DA improved the accuracy of groundwater storage estimates by as much as 25 %. The inclusion of error correlations provided an equal or greater improvement in the estimates. In contrast, a validation against in situ streamflow data from two river gauges showed no significant benefits of GRACE DA. This is likely due to the limited spatial and temporal resolution of GRACE observations. Finally, results of the GRACE DA study

  15. Geoenvironmental and structural studies for developing new water resources in arid and semi-arid regions using remote sensing and GIS (United States)

    Amer, Reda Mohammed


    Water crises are rising with increasing world population and decreasing of freshwater resources. This problem is magnified in the arid and semi-arid regions because surface water resources are very limited and highly unreliable and therefore groundwater is the primary source of water supply in these regions. This study presents an integrated approach for the identification of groundwater occurrences using remote sensing, geological, and geophysical data, and establishing sustainable paths to groundwater management. The Central Eastern Desert (CED) of Egypt was selected as a test site for this study because its climate is arid and there is an urgent need to identify potential areas for groundwater accumulations. Field investigations indicated that the CED has three types of aquifers; shallow alluvial (SA), and fracture zone (FZ) aquifers in the valley depressions, and deep aquifers in the sedimentary succession that range in age from Late Cretaceous to Recent in the marginal extensional sub-basins (ESB) along the Red Sea coast. I developed three models: (1) a Geographic Information System (GIS) model for groundwater potential in the SA and FZ shallow aquifers; (2) a kinematic model for the development of the ESB; and (3) a groundwater budget model for the ESB aquifers. The GIS model is based on the analysis of remote sensing data of the Phased Array L-band Synthetic Aperture Radar, the Landsat Enhanced Thematic Mapper Plus, and the Advanced Spaceborne Thermal Emission and Reflection Radiometer digital elevation model. The model was evaluated and proven successful against the existing shallow water wells, and by geophysical surveys using Ground Penetrating Radar and Geoelectric methods. The kinematic model indicated that the ESB were formed in the orthogonal rifting phase in the late Oligocene that is followed by oblique rifting phase during the early Miocene which resulted to the en-echelon pattern of the inland ESB and nucleation of the rift depression into

  16. Forecasting wheat and barley crop production in arid and semi-arid regions using remotely sensed primary productivity and crop phenology: A case study in Iraq. (United States)

    Qader, Sarchil Hama; Dash, Jadunandan; Atkinson, Peter M


    Crop production and yield estimation using remotely sensed data have been studied widely, but such information is generally scarce in arid and semi-arid regions. In these regions, inter-annual variation in climatic factors (such as rainfall) combined with anthropogenic factors (such as civil war) pose major risks to food security. Thus, an operational crop production estimation and forecasting system is required to help decision-makers to make early estimates of potential food availability. Data from NASA's MODIS with official crop statistics were combined to develop an empirical regression-based model to forecast winter wheat and barley production in Iraq. The study explores remotely sensed indices representing crop productivity over the crop growing season to find the optimal correlation with crop production. The potential of three different remotely sensed indices, and information related to the phenology of crops, for forecasting crop production at the governorate level was tested and their results were validated using the leave-one-year-out approach. Despite testing several methodological approaches, and extensive spatio-temporal analysis, this paper depicts the difficulty in estimating crop yield on an annual base using current satellite low-resolution data. However, more precise estimates of crop production were possible. The result of the current research implies that the date of the maximum vegetation index (VI) offered the most accurate forecast of crop production with an average R2=0.70 compared to the date of MODIS EVI (Avg R2=0.68) and a NPP (Avg R2=0.66). When winter wheat and barley production were forecasted using NDVI, EVI and NPP and compared to official statistics, the relative error ranged from -20 to 20%, -45 to 28% and -48 to 22%, respectively. The research indicated that remotely sensed indices could characterize and forecast crop production more accurately than simple cropping area, which was treated as a null model against which to evaluate

  17. Effects of a Reservoir Water on the GW Quality in a Coastal Aquifer of Semi-arid Region, North-east of Tunisia (United States)

    Uchida, C.; Kawachi, A.; Tsujimura, M.; Tarhouni, J.


    This study investigated effects of a reservoir water in a salinized shallow aquifer based on spatial distribution of geochemical properties in groundwater (GW). In many coastal shallow aquifers of arid and semi-arid regions, groundwater table (GWT) depression and salinization have occurred due to GW overexploitation. In Korba aquifer, north-east of Tunisia, after a dam reservoir has been constructed in order to assure a water resource for irrigation, improvement of GW level and quality have been observed in the downstream area of the dam (area-A), while the GW in the other area (area-B) still has high salinity. This study, therefore, aimed to investigate the effects of the reservoir water on the GW quality. In June 2013, water quality survey and sampling were carried out at 60 wells (GW), a dam reservoir, river and the sea. Major ions, boron, bromide, and oxygen-18 and deuterium in collected samples were analyzed. From the results, in the area-B, the GWT was lower than the sea level and the high salinity were observed. The Br- concentration of the GW was correlated with the Cl- concentration, and the values of B/Cl- and Br-/Cl- of the GW were similar to the seawater. Since the GWT depression allowed the seawater to intrude into the aquifer, the GW salinization occurred in this area. On the other hand, in the area-A, GWT was higher than the seawater level, and the Na+ and Cl- concentrations were lower than the area-B. Especially, in the irrigated areas by using the reservoir water, the isotopic values, B/Cl- and Br-/Cl- of the GW were relatively higher than the others. The reservoir water has high isotopic values due to evaporation effect, and the B/Cl- and Br-/Cl- values become higher due to organic matters in sediment of the reservoir or soil in the filtration process. Thus, in addition to the direct infiltration from the reservoir into the aquifer, irrigation using a reservoir water probably has a positive impact on the GW quality in this area.

  18. Evaluating persistence and identifying trends and abrupt changes in monthly and annual rainfalls of a semi-arid region in Western India (United States)

    Machiwal, Deepesh; Jha, Madan Kumar


    In this study, 43-year (1965-2007) monthly and annual rainfall time series of ten rainfall stations in a semi-arid region of western India are analyzed by adopting three tests for testing normality and by applying autoregressive technique for exploring persistence. Gradual trends are identified by three tests, and their magnitudes are assessed by the Sen's slope estimator. Also, abrupt changes are detected by using four tests and they are further confirmed by two tests. Box-whisker plots revealed that the rainfalls of June and September are right skewed for all the stations. The annual rainfalls of Bhinder, Dhariawad, and Gogunda stations are found considerably right skewed. The normality tests indicated that the rainfall of July does not deviate from the normal distribution at all the stations. However, the annual rainfall is found non-normal at five stations. The monthly rainfalls of June, July, and August have persistence respectively at three (Mavli, Salumber, and Sarada), two (Kherwara and Sarada), and one (Mavli) stations, whereas the annual rainfall has persistence at Girwa and Mavli stations. Significantly increasing trend is detected at Mavli in the rainfall of July and in the annual rainfall ( p value > 0.05), while the negative trend in August rainfall at Dhariawad is found significant ( p value > 0.10). This study revealed that the presence of serial correlation does not affect the performance of the Mann-Kendall test. Mean values of trend magnitudes for the rainfalls of June, July, August, and September are 0.3, 0.8, -0.4, and 0.4 mm year-1, respectively, and the overall mean value for the annual rainfall is 0.9 mm year-1. It is found that the standard normal homogeneity test and the Pettitt test are biased towards the end of the series to locate a change point. Conversely, the Bayesian test has a tendency to look for a change point in the beginning of time series. Confirmed abrupt changes in the rainfall time series are found in the year 2003 (Bhinder

  19. Comparing the efficiency of digital and conventional soil mapping to predict soil types in a semi-arid region in Iran (United States)

    Zeraatpisheh, Mojtaba; Ayoubi, Shamsollah; Jafari, Azam; Finke, Peter


    The efficiency of different digital and conventional soil mapping approaches to produce categorical maps of soil types is determined by cost, sample size, accuracy and the selected taxonomic level. The efficiency of digital and conventional soil mapping approaches was examined in the semi-arid region of Borujen, central Iran. This research aimed to (i) compare two digital soil mapping approaches including Multinomial logistic regression and random forest, with the conventional soil mapping approach at four soil taxonomic levels (order, suborder, great group and subgroup levels), (ii) validate the predicted soil maps by the same validation data set to determine the best method for producing the soil maps, and (iii) select the best soil taxonomic level by different approaches at three sample sizes (100, 80, and 60 point observations), in two scenarios with and without a geomorphology map as a spatial covariate. In most predicted maps, using both digital soil mapping approaches, the best results were obtained using the combination of terrain attributes and the geomorphology map, although differences between the scenarios with and without the geomorphology map were not significant. Employing the geomorphology map increased map purity and the Kappa index, and led to a decrease in the 'noisiness' of soil maps. Multinomial logistic regression had better performance at higher taxonomic levels (order and suborder levels); however, random forest showed better performance at lower taxonomic levels (great group and subgroup levels). Multinomial logistic regression was less sensitive than random forest to a decrease in the number of training observations. The conventional soil mapping method produced a map with larger minimum polygon size because of traditional cartographic criteria used to make the geological map 1:100,000 (on which the conventional soil mapping map was largely based). Likewise, conventional soil mapping map had also a larger average polygon size that resulted

  20. Evaluation of the SAFRAN-ISBA-RAPID hydrometeorological chain on a mountainous catchment in a semi-arid region. Case of the Rheraya (Marrakech, Morocco) (United States)

    Szczypta, Camille; Gascoin, Simon; Habets, Florence; Saaidi, Amina; Berjamy, Brahim; Marchane, Ahmed; Boulet, Gilles; Hanich, Lahoucine; Jarlan, Lionel


    The water content of snow pack is an important resource for many watershed in semi-arid areas where downstream plains are dominated by irrigated agriculture. As part of the ANR Amethyst, this work is to develop, adapt and evaluate a hydro-meteorological forecasting chain for quantifying streamflows at the outlet of a mountainous watershed (Rheraya wadi, Marrakech region, Morocco), a pilot basin instrumented since 2003 as part of SudMed project. Two sets of atmospheric forcing were used: (1) The first was generated by spatializing meteorological data observed on 6 stations (Asni, Aremdt, Tachedert, Oukaimeden, Imskerbour and Neltner) using the semi-physical module Micromet (Liston and Elder, 2006) on the hydrological period September 2003 - August 2012; (2) the second is provided by the SAFRAN re-analysis, implemented by the Metoffice of Morocco (Casablanca, Morocco), during the period August 2004 - July 2008. These two sets were then used as inputs for the ISBA surface model, within the modeling platform SURFEX. Finally, runoff and drainage simulations derived from ISBA were forced into the hydrological model RAPID to predict streamflows. The flows predictions and the snow covered area (SCA) were compared respectively to the observations available for the 2003-2009 period and to the daily MODIS products of SCA. Despite time unsystematic lags and low biases on flow values, the initial results are encouraging due to topographical and hydro-complexity of the studied area. Despite a slight tendency to underestimate the SCA for the "Micromet" run and to over-estimate for the "Safran" run, SCA is well reproduced with a determination coefficient of r²=0.76 and r²=0.79, respectively. Given the complex topography of the basin, a sensitivity analysis to the size of the grid point (from 8 km to 250 m) was conducted. If the different simulated series of SCA are close from a resolution to another, streamflows simulations are, by contrast, highly sensitive to the resolution

  1. Conservation tillage of rainfed maize in semi-arid Zimbabwe: A review

    NARCIS (Netherlands)

    Nyakudya, I.W.; Stroosnijder, L.


    Food security in Sub-Saharan Africa, particularly in semi-arid tropics (41% of the region; 6 months of dry season) is threatened by droughts, dry spells and infertile soils. In Zimbabwe, 74% of smallholder farming areas are located in semi-arid areas mostly in areas with soils of low fertility and

  2. Rainwater harvesting in arid and semi-arid zones

    NARCIS (Netherlands)

    Boers, T.M.


    In arid and semi-arid regions, the scarcity of water can be alleviated by rainwater harvesting, which is defined as a method of inducing, collecting, storing, and conserving local surface runoff for agriculture. Rainwater harvesting can be applied with different

  3. Environmental Effects of Irrigation in Arid and Semi-Arid Regions Efectos Ambientales del Riego en Regiones Áridas y Semi-Áridas en América Latina

    Directory of Open Access Journals (Sweden)

    Alicia Fernández Cirelli


    Full Text Available This article reviews the state of the art with respect to the environmental effects of irrigated agriculture on water and soil quality in arid and semi-arid regions on a field scale. Information is scarce and fragmentary. Examples in selected areas of other arid and semi-arid regions in the world clearly show the importance of studying the environmental impact of irrigation practices on water and soil quality. Studies mainly refer to waterlogging and salinization. As regards agrochemicals, fertilizers have been taken into account through nitrate leaching. The impact of micropollutants such as pesticides and heavy metals on water and soil quality is studied mainly by modeling. Pharmaceutical compounds emerge as pollutants when wastewater is used for irrigation without any previous treatment, situation which is now the object of new studies. There is an obvious need to study in-depth knowledge related to appropriate technologies for the use, treatment, and reuse of wastewater which is a valuable resource in arid and semi-arid regions.En este trabajo se presenta una revisión del estado del arte relativo a los efectos ambientales de la agricultura bajo riego en la calidad del agua y de los suelos en regiones semiáridas y áridas de América Latina a escala de campo. La información relevada es escasa y fragmentaria. Ejemplos en áreas seleccionadas de otras regiones del mundo muestran claramente la importancia del estudio del impacto ambiental de las prácticas de riego en la calidad de agua y del suelo. La mayor parte de los estudios se refieren a anegamiento y salinización de suelos. En relación a los agroquímicos, los fertilizantes han recibido mayor atención, en particular considerando la lixiviación de nitratos. El impacto de los microcontaminantes, como los pesticidas o los metales pesados, se ha estudiado mayormente a través de la aplicación de modelos. Los compuestos farmacéuticos surgen como contaminantes cuando las aguas servidas

  4. Do Red Edge and Texture Attributes from High-Resolution Satellite Data Improve Wood Volume Estimation in a Semi-Arid Mountainous Region?

    DEFF Research Database (Denmark)

    Schumacher, Paul; Mislimshoeva, Bunafsha; Brenning, Alexander


    Remote sensing-based woody biomass quantification in sparsely-vegetated areas is often limited when using only common broadband vegetation indices as input data for correlation with ground-based measured biomass information. Red edge indices and texture attributes are often suggested as a means...... red edge and texture attributes, to estimate wood volume in semi-arid ecosystems characterized by scarce vegetation. LASSO (Least Absolute Shrinkage and Selection Operator) and random forest were used as predictive models relating in situ-measured aboveground standing wood volume to satellite data...

  5. Potential of remote sensing data for improving water resources management in semi-arid regions: a case study in Burkina Faso (United States)

    Papa, M. N.; Ciervo, F.; Koussoube, y.; Di Martino, G.; Iodice, A.; Natale, A.; Riccio, D.; Ruello, G.; Zinno, I.


    In this work we present the rationale and the first results of a Cosmo-SkyMed AO project devoted to use high resolution synthetic aperture radar data for water resource management in semi-arid regions. A case study was developed in Burkina Faso, one of the poorest countries of the world, where almost 80% of the population lives in rural areas depending from agriculture and livestock. It is characterized by the alternation of a rainy (3 months) and a dry (9 months) season, with extreme climate conditions (drought and floods). The project was approved by the Italian Space Agency, that provided Cosmo SkyMed Stripmap (3m resolution) and Spotligth (1m resolution) SAR images. The study area is in the northern part of Burkina Faso around the village of Bidi. A first study is related on the identification of eroded areas, which are indicative of desertification processes. Eroded soils are no more able to absorb and drain water, so that their humidity and, as a consequence, their dielectric constant and conductivity are almost independent by the precipitation. By comparing SAR images acquired during the rainy and the dry seasons, the eroded soils do not change their reflectivity and they can be identified by change detection techniques. In this work we employ innovative fractal change detection techniques, based on the image spectrum evaluation and the comparison of the fractal dimension. As the precipitations occur only during three months, it is crucial to collect water in the rainy season, by the means of artificial basins, in order to irrigate the fields in the dry season. The construction of little artificial basins is usually carried out under the initiative of small associations of farmers. The location, design and management of the basins sometimes is not rational, for the lack of all the information needed for the design. The best location for the construction of a new artificial basin depends on the total volume of surface water that may be collected in one year

  6. Assessing gendered roles in water decision-making in semi-arid regions through sex-disaggregated water data with UNESCO-WWAP gender toolkit (United States)

    Miletto, Michela; Greco, Francesca; Belfiore, Elena


    . Extreme climatic events like floods and droughts could severely impact the status of water resources and dependent ecosystems and the sustainability of household activities and local economies, given the absence of gender sensitive preparedness to hydrological and meteorological extremes. This paper describes the application of the WWAP Gender Toolkit to water data assessments in semi-arid region of the Stampriet transboundary aquifer shared by Botwana, Namibia and South Africa, in the framework of the "Groundwater Resources Governance in Transboundary Aquifers" - GGRETA project, led and executed by the UNESCO International Hydrological Programme (IHP), and financed by the Swiss Agency for Development and Cooperation (SDC). The tests in the field proved the reliability of WWAP gender toolkit and selected gender-sensitive indicators in the freshwater assessment. Further analysis could inform on the gaps and needs for climate adaptation practices. Field data identified socially-determined differences in roles, and confirmed the prevalent role of women in managing freshwater for drinking and sanitation purposes within the household boundaries, while decision-making for water allocation and use (with implications on hydrological risk) for agriculture and livestock purposes, is broadly under men's responsibility.

  7. Biodigestor for validation of the productive system self-sustainable in the Brazil semi-arid; Biodigestor para validacao de sistema produtivo auto-sustentavel no semi-arido

    Energy Technology Data Exchange (ETDEWEB)

    Carvalho, Paulo C.M. [Universidade Federal do Ceara (UFCE), Fortaleza, CE (Brazil). Dept. de Engenharia Eletrica; Silveira Neto, Jose W.; Diniz, Magilce M.N. [Instituto Joazeiro de Desenvolvimento Sustentavel, Fortaleza, CE (Brazil); Canafistula, Francisco J.F. [Universidade Federal do Ceara (UFCE), Fortaleza, CE (Brazil). Dept. de Engenharia Agricola


    The present paper shows the first phase of a project about the use of digester adapted to the conditions of the semi-arid areas of the Brazilian Northeast region. The project aims to analyze the technical, economical, financial and environmental viability of a production system based on the use of digesters. (author)

  8. Application of a statistical model for the assessment of environmental quality in neotropical semi-arid reservoirs. (United States)

    de Lira Azevêdo, Evaldo; de Lucena Barbosa, José Etham; Viana, Leandro Gomes; Anacleto, Maria José Pinheiro; Callisto, Marcos; Molozzi, Joseline


    The aim of this study was to develop a statistical model to assess the environmental quality of reservoirs located in semi-arid region using metrics of anthropogenic disturbance, water quality variables, and benthic macroinvertebrate communities as indicators. The proposed model was applied to 60 sites located in three reservoirs in the Paraíba river basin, Brazilian semi-arid region. Collections were made in December 2011. In each site, we collected one sample of benthic macroinvertebrates and one water sample for the determination of physical and chemical parameters. Characterization of the landscape was made through application of 10 physical habitat protocols on each site for the collected information on disturbance and subsequent calculation of disturbance metrics. The results showed the formation of two groups: group 1, consisting of 16 minimally altered sites, and group 2, with 44 severely altered sites. The proposed statistical model was sensitive enough to detect changes. In the minimally altered group, the Chironomids Aedokritus and Fissimentum were dominant, indicating a higher environmental quality, while Coelotanypus and Chironomus were abundant in severely altered sites with lower environmental quality. The conservation and management of reservoirs in semi-arid regions should be intensified in view of the need to maintain the environmental quality of these ecosystems.

  9. Perdas de solo e de água em sistemas de captação in situ no Semi-Árido brasileiro Soil and water losses in situ water harvesting systems in the brazilian semi-arid

    Directory of Open Access Journals (Sweden)

    Luiza T. L. Brito


    Full Text Available Os sistemas de cultivo utilizados no semi-árido brasileiro apresentam riscos de perda devido à irregularidade das chuvas, devendo-se associá-los a práticas que propiciem maior infiltração e, conseqüentemente, menor erosão, o que pode ser obtido por meio de técnicas de captação de água de chuva in situ. Neste trabalho, teve-se o objetivo de avaliar as perdas de água e de solo em área cultivada com milho (Zea mays L., submetida a diferentes sistemas de preparo do solo, correspondendo aos tratamentos Guimarães Duque (T1; aração profunda (T2; aração parcial (T3 e sulcos barrados (T4, comparados com o sistema tradicional (T5, que corresponde ao plantio sem preparo do solo. Após cada evento de chuva, a água e o solo escoados foram coletados e medidos. A umidade do solo em diferentes profundidades foi monitorada durante o ciclo de produção da cultura e avaliada a produtividade dos grãos por meio da análise de variância. A partir dos resultados, pode-se observar que o método Guimarães Duque (T1 proporcionou maiores perdas de água (6.696 L e de solo (15.225 kg ha-1, enquanto as menores perdas foram obtidas com os sulcos barrados (T4, correspondendo a 1.066 L e 1.022 kg ha-1, respectivamente. Nesse tratamento (T4, também foi obtida a maior produtividade de grãos (606 kg ha-1, apresentando-se como o sistema mais indicado para as condições analisadas.The cropping systems used in the Brazilian semi-arid show risks of losses due to irregularity of rainfall, requiring the use of practices which produce higher water infiltration and, as a consequence, lower soil erosion, which can be obtained through in situ rainwater harvest techniques. This study had the objective of evaluating soil and water losses in a corn (Zea mays L. area subjected to different soil preparation systems: Guimarães Duque (T1, deep plowing (T2, partial plowing (T3, and furrows with barriers (T4, compared to the traditional system (T5, i.e., plain planting

  10. Biological Invasion Influences the Outcome of Plant-Soil Feedback in the Invasive Plant Species from the Brazilian Semi-arid. (United States)

    de Souza, Tancredo Augusto Feitosa; de Andrade, Leonaldo Alves; Freitas, Helena; da Silva Sandim, Aline


    Plant-soil feedback is recognized as the mutual interaction between plants and soil microorganisms, but its role on the biological invasion of the Brazilian tropical seasonal dry forest by invasive plants still remains unclear. Here, we analyzed and compared the arbuscular mycorrhizal fungi (AMF) communities and soil characteristics from the root zone of invasive and native plants, and tested how these AMF communities affect the development of four invasive plant species (Cryptostegia madagascariensis, Parkinsonia aculeata, Prosopis juliflora, and Sesbania virgata). Our field sampling revealed that AMF diversity and frequency of the Order Diversisporales were positively correlated with the root zone of the native plants, whereas AMF dominance and frequency of the Order Glomerales were positively correlated with the root zone of invasive plants. We grew the invasive plants in soil inoculated with AMF species from the root zone of invasive (I changed) and native (I unaltered) plant species. We also performed a third treatment with sterilized soil inoculum (control). We examined the effects of these three AMF inoculums on plant dry biomass, root colonization, plant phosphorous concentration, and plant responsiveness to mycorrhizas. We found that I unaltered and I changed promoted the growth of all invasive plants and led to a higher plant dry biomass, mycorrhizal colonization, and P uptake than control, but I changed showed better results on these variables than I unaltered. For plant responsiveness to mycorrhizas and fungal inoculum effect on plant P concentration, we found positive feedback between changed-AMF community (I changed) and three of the studied invasive plants: C. madagascariensis, P. aculeata, and S. virgata.

  11. Integrating management objectives and grazing strategies on semi-arid rangelands (United States)

    US Fish and Wildlife Service, Department of the Interior — Rangelands account for almost half of Nebraska's 24 million acres. Much of these expansive natural resource areas are in the semi-arid climatic region of Nebraska...

  12. Influência da aptidão produtiva (leite ou carne sobre a libido de bodes de raças exóticas e naturais da região semi-árida do nordeste brasileiro Influence of the productive aptitude (milk or meat on the libido of exotic male goats it is naturalized to the semi-arid area from the brazilian northeast region

    Directory of Open Access Journals (Sweden)

    Fernando Carlos Borja dos Santos


    Full Text Available Dezesseis reprodutores caprinos agrupados de acordo com a aptidão produtiva (carne ou leite foram avaliados quanto à libido. Em cada grupo racial (Anglo-Nubiano e Pardo-Sertanejo - para leite; e Boer e Moxotó - para carne, havia quatro animais. Cinco fêmeas mestiças de Anglo-Nubiano foram utilizadas, todas elas estrogenizadas. O experimento foi realizado em Patos - PB (região semi-árida do Nordeste brasileiro durante 42 dias, entre agosto e setembro de 2002. Os trinta dias iniciais foram reservados para o período adaptativo dos animais e os últimos doze dias, para o processo intensivo de coleta seminal, que obedeceu a um sistema contínuo e crescente de coletas dividido em três fases, cada uma com quatro dias: fase 1, uma coleta ao dia; fase 2, três coletas ao dia; fase 3, seis coletas ao dia. Durante as coletas seminais, todo o comportamento sexual dos bodes foi monitorado, inclusive a libido. Encontrou-se influência significativa (P Sixteen male goats were agrouped accord to productive aptitude (meat or milk and they were evaluated for the libido. In each racial group (Anglo-Nubiano and Pardo-Sertanejo - for milk; and Boer and Moxotó - for meat being a total of four animals. Five females crosbreed from Anglo-Nubiano in oestrous were used.. The experiment was conducted in Patos - PB (Brazilian Northeast, semi-area region during 42 days from August and September of 2002. The thirty initial days were reserved for the adaptadion period of the animals and the last twelve days the animals were submitted to intensive process of seminal collection in a continuous and growing system of collections divided in three phases, each one with four days: phase 1, a collection a day; phase 2, three collections a day; phase 3, six collections a day. During the seminal collections the whole sexual behavior of the male goats was monitored, besides the libido. The data shown a significant influence (P <0.05 on the productive aptitude as well the

  13. Correlations of condition factor and gonadosomatic, hepatosomatic and lipo-somatic relations of Leptodactylus macrosternum (ANURA: Leptodactylidae in the Brazilian Semi-arid

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    Full Text Available ABSTRACT The objective of this study was to assess variations of the condition factor (K1 in relation to the gonadosomatic- RGS and energy reserves (hepatosomatic - RWL and liposomatic - RFB relations of Leptodactylus macrosternum and their relationship to climate variation in the Northeast of Brazil, Caatinga area, state of Paraiba. The animals were captured fortnightly through active collecting, between January and December 2013. Significant differences were observed in the monthly variations of K1, RGS and RFB indices in male and female L. macrosternum over the months of collection. In males, K1 showed no significant relationship with the other variables. In females, RGS values only show notable correlations with RWF and K1 values. K1 values showed significant correlations with all other weight and length ratios. Climate change in the HFOB region showed significant relationships with the variation of the indexes evaluated, with the exception of RWF. The variation of K1, RGS, RWL and RFB values over the months of collection as well as their relation with the local climatic variation, showed a brief reproductive activity for the species.

  14. Assessment of vulnerability in karst aquifers using a quantitative integrated numerical model: catchment characterization and high resolution monitoring - Application to semi-arid regions- Lebanon. (United States)

    Doummar, Joanna; Aoun, Michel; Andari, Fouad


    Karst aquifers are highly heterogeneous and characterized by a duality of recharge (concentrated; fast versus diffuse; slow) and a duality of flow which directly influences groundwater flow and spring responses. Given this heterogeneity in flow and infiltration, karst aquifers do not always obey standard hydraulic laws. Therefore the assessment of their vulnerability reveals to be challenging. Studies have shown that vulnerability of aquifers is highly governed by recharge to groundwater. On the other hand specific parameters appear to play a major role in the spatial and temporal distribution of infiltration on a karst system, thus greatly influencing the discharge rates observed at a karst spring, and consequently the vulnerability of a spring. This heterogeneity can only be depicted using an integrated numerical model to quantify recharge spatially and assess the spatial and temporal vulnerability of a catchment for contamination. In the framework of a three-year PEER NSF/USAID funded project, the vulnerability of a karst catchment in Lebanon is assessed quantitatively using a numerical approach. The aim of the project is also to refine actual evapotranspiration rates and spatial recharge distribution in a semi arid environment. For this purpose, a monitoring network was installed since July 2014 on two different pilot karst catchment (drained by Qachqouch Spring and Assal Spring) to collect high resolution data to be used in an integrated catchment numerical model with MIKE SHE, DHI including climate, unsaturated zone, and saturated zone. Catchment characterization essential for the model included geological mapping and karst features (e.g., dolines) survey as they contribute to fast flow. Tracer experiments were performed under different flow conditions (snow melt and low flow) to delineate the catchment area, reveal groundwater velocities and response to snowmelt events. An assessment of spring response after precipitation events allowed the estimation of the

  15. Evaluating the influence of geo-environmental factors on gully erosion in a semi-arid region of Iran: An integrated framework. (United States)

    Rahmati, Omid; Tahmasebipour, Naser; Haghizadeh, Ali; Pourghasemi, Hamid Reza; Feizizadeh, Bakhtiar


    Despite the importance of soil erosion in sustainable development goals in arid and semi-arid areas, the study of the geo-environmental conditions and factors influencing gully erosion occurrence is rarely undertaken. As effort to this challenge, the main objective of this study is to apply an integrated approach of Geographic Object-Based Image Analysis (GEOBIA) together with high-spatial resolution imagery (SPOT-5) for detecting gully erosion features at the Kashkan-Poldokhtar watershed, Iran. We also aimed to apply a Conditional Probability (CP) model for establishing the spatial relationship between gullies and the Geo-Environmental Factors (GEFs). The gully erosion inventory map prepared using GEOBIA and field surveying was randomly partitioned into two subsets: (1) part 1 that contains 70% was used in the training phase of the CP model; (2) part 2 is a validation dataset (30%) for validation of the model and to confirm its accuracy. Prediction performances of the GEOBIA and CP model were checked by overall accuracy and Receiver Operating Characteristics (ROC) curve methods, respectively. In addition, the influence of all GEFs on gully erosion was evaluated by performing a sensitivity analysis model. The validation findings illustrated that overall accuracy for GEOBIA approach and the area under the ROC curve for the CP model were 92.4% and 89.9%, respectively. Also, based on sensitivity analysis, soil texture, drainage density, and lithology represent significantly effects on the gully erosion occurrence. This study has shown that the integrated framework can be successfully used for modeling gully erosion occurrence in a data-poor environment. Copyright © 2016 Elsevier B.V. All rights reserved.

  16. Columnar-integrated aerosol optical properties and classification of different aerosol types over the semi-arid region, Anantapur, Andhra Pradesh. (United States)

    Rama, Gopal K; Arafath, S Md; Balakrishnaiah, G; Raja, Obul Reddy K; Siva, Kumar Reddy N; Lingaswamy, A P; Pavan, Kumari S; Uma, Devi K; Reddy, R R; Suresh, Babu S


    This study presents a characterization of aerosol columnar properties measured at a semi-arid station Anantapur in the southern part of India during the period from October 2012 to September 2013. Aerosol optical depth (AOD) and Angstrom exponent (α) have been retrieved from Microtops II Sunphotometer over the observation site. The results show that a pronounced spectral and monthly variability in the optical properties of aerosols is mainly due to anthropogenic sources. The results show that the spectral curvature can effectively be used as a tool for aerosol type discrimination, since the fine-mode aerosols exhibit negative curvature, while the coarse-mode particles are positive. The classification of aerosols is also proposed by using the values of AOD at 500 nm and Angstrom exponent values (α(380-870)) by applying threshold values obtained from the frequency distribution of AOD. The results of the analysis were identified by four individual components (anthropogenic/biomass burning, coarse/dust, coarse/marine, clean continental) of different origin and compositions. The most frequent situations observed over the site are that due to the anthropogenic/biomass burning situations which account for about 45.37%, followed by coarse/dust (43.64%), clean continental (7.2%) and coarse/marine (3.82%) during summer. The identification of the aerosol source type and the modification processes are analyzed by using the Gobbi et al. (2007) classification scheme based on the measured scattering properties (α, dα) derived from the Microtops II Sunphotometer. Copyright © 2015 Elsevier B.V. All rights reserved.

  17. Myxomycetes ocorrentes em áreas de caatinga e brejo de altitude no sertão de Pernambuco, Brasil Myxomycetes from caatinga and brejo de altitude areas in the semi-arid region of Pernambuco, Brazil

    Directory of Open Access Journals (Sweden)

    Nylber Augusto da Silva


    Full Text Available O bioma Caatinga, localizado na região semiárida brasileira, está distribuído em nove estados, incluindo Pernambuco. Os objetivos deste estudo foram: obter informações que contribuam para a compreensão da diversidade alfa e gama da microbiota da Caatinga; comparar a composição da mixobiota em áreas de caatinga situadas nos municípios de Serra Talhada (ST e Mirandiba (M com a encontrada em um enclave de floresta úmida (brejo de altitude situado no município de Triunfo (T. Os espécimes foram coletados sobre restos lenhosos (173, folhedo (26, restos de plantas suculentas (3, casca de árvore viva (1 e fezes de herbívoros (1. Hemitrichia calyculata foi a espécie mais abundante (60 registros; outras espécies comuns foram Arcyria cinerea (20, Ceratiomyxa fruticulosa (19, A. denudata (16 e H. serpula (13. Apresenta-se uma lista comentada de 37 espécies, distribuídas em 17 gêneros, sete famílias e cinco ordens. A mixobiota dos três ambientes difere entre si: CC M/ST = 0,25; CC M/T = 0,06; CC ST/T = 0,39. A relação espécie/gênero foi muito baixa na caatinga e relativamente alta na floresta úmida (S/G M = 1,0; S/G ST= 1,3; S/G T = 2,14. A abundância de espécimes e o número de espécies (M = 4/4; ST= 26/12; T= 172/29 tendem a aumentar com a elevação da altitude e da pluviosidade. Fuligo megaspora é referida pela primeira vez para o Nordeste e Didymium perforatum é um novo registro para o Brasil.The Caatinga biome, situated in the Brazilian semi-arid region, is distributed among the territories of nine states, including Pernambuco. The objectives of this study were: (1 to understand the alpha and gamma diversity of the Caatinga myxobiota; and (2 to compare the composition of the myxobiota present in two areas of typical xerophilous vegetation situated in Serra Talhada (ST and Mirandiba (M municipalities with an enclave of rain forest situated in the municipality of Triunfo (T. Specimens were collected on woody debris (173

  18. The legacy of organochlorine pesticide usage in a tropical semi-arid region (Jaguaribe River, Ceará, Brazil): Implications of the influence of sediment parameters on occurrence, distribution and fate. (United States)

    Oliveira, André H B; Cavalcante, Rivelino M; Duaví, Wersângela C; Fernandes, Gabrielle M; Nascimento, Ronaldo F; Queiroz, Maria E L R; Mendonça, Kamila V


    Between the 1940s and 1990s, immeasurable amounts of organochlorine pesticides (OCPs) were used in endemic disease control campaigns and agriculture in the tropical semi-arid regions of Brazil. The present study evaluated the legacy of banned OCP usage, considering the levels, ecological risk and dependence on sediment physicochemical properties for the fate and distribution in the Jaguaribe River. The sum concentration of OCPs (ΣOCPs) ranged from 5.09 to 154.43 ng·g(-1), comparable to the levels found in other tropical and subtropical regions that have traditionally used OCPs. The environmental and geographical distribution pattern of p,p-DDT, p,p-DDD and p,p-DDE shows that the estuarine zone contained more than 3.5 times the levels observed in the fluvial region, indicating that the estuary of the Jaguaribe River is a sink. The temporal pattern indicates application of dichloro-diphenyl-trichloroethanes (DDTs) in the past; however, there is evidence of recent input of these pesticides. High ecological risk was observed for levels of γ-hexachlorocyclohexanes (γ-HCH) and heptachlor, and moderate ecological risk was observed for levels of DDTs in sediments from the Jaguaribe River. The heptachlor, γ-HCH and hexachlorobenzene (HCB) concentrations depend on the organic and inorganic fractions of sediment from the Jaguaribe River, whereas the p,p-DDE, p,p-DDD, p,p-DDT and α-endosulfan concentrations depend solely on the organic fraction of the sediment.

  19. Does total tannin content explain the use value of spontaneous medicinal plants from the Brazilian semi-arid region?

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    Julio M. Monteiro

    Full Text Available Due to the current predatory exploitation and consequent extinction of native medicinal plants around the world, strategies have been proposed aiming at the sustainable use of these resources. Accordingly, this study aims at verifying the differences in tannin compounds content in the bark of eleven species with high use value (UV and also relating the amounts of tannins with their therapeutic indications. To quantify the total phenolic content in the samples the Folin-Ciocalteu reagent was used, and for total tannins chemical casein precipitation was applied. The amount of tannins ranged intra-specifically and the greater variation was found for Anadenanthera colubrina(angico that displayed between 157.57 and 107.39 mg/g. The lowest variation occurred in Lafoensia replicata(mangabeira with values ranging between 76.55 and 68.96 mg/g. There were significant differences between several of the eleven species and according to the simple regression analysis, the quantities of tannins found failed to justify their UV. Thus, it was not possible to establish whether the amount of total tannins influenced to a greater or lesser degree in the accumulation of knowledge. Moreover, this is the first study to investigate the relationship between the amount of total tannins and local botanical knowledge expressed by the UV.

  20. Sediment delivery ratio in a small semi-arid watershed under conditions of low connectivity

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    Julio Cesar Neves dos Santos

    Full Text Available ABSTRACT The semi-arid region in the northeast of Brazil is characterised by rains of high intensity and short duration, with the processes of erosion being aggravated by an inappropriate land-use model. In this region, the lack of measured data for runoff and sediment yield increases the need to apply hydro-sedimentological models in estimating erosion, requiring knowledge of the actual sediment delivery ratio for the region. The aim of this study therefore, was to map soil erosion, making use of the Universal Soil Loss Equation (USLE, in the Iguatu Experimental Watershed (IEW. The mean annual sediment delivery ratio (SDR, and the SDR for individual events, was calculated from hydro-sedimentological measurements, contributing to an understanding of the processes of sediment propagation in the Brazilian semi-arid region, allowing identification of areas susceptible to water erosion. The IEW has an area of 16.74 km2 and is equipped with sensors for the continuous measurement of rainfall, flow and sediment yield. The mean annual SDR for the IEW was 0.37%. The SDR for individual rainfall events ranged from 0.08 to 1.67%, with an average of 0.68%. Among the main variables that influence the SDR for individual events is the magnitude of rainfall depth and antecedent soil moisture that can be better represented by the total antecedent precipitation of the previous 15 days. According to maps of soil loss, only 6.27% of the watershed presented losses beyond tolerable limits.

  1. Fuel consumption of tractor for different soil types in semi-arid regions; Consumo de combustivel de um trator agricola para diferentes tipos de solo em regioes semi-aridas

    Energy Technology Data Exchange (ETDEWEB)

    Montanha, Gustavo K. [Universidade Estadual Paulista (FAC/UNESP), Botucatu, SP (Brazil). Fac. de Ciencias Agronomicas. Dept. de Engenharia Rural], E-mail:; Guerra, Saulo P.S. [Universidade Estadual Paulista (UNESP), Botucatu, SP (Brazil). Dept. de Gestao e Tecnologia Agroindustrial; Andrade-Sanchez, Pedro; Heun, John [The University of Arizona, Maricopa, AZ (United States); Monteiro, Leonardo A. [The University of Arizona (MAC/UA), Maricopa, AZ (United States). Maricopa Agricultural Center


    The appropriate use of agricultural machinery enables greater operational efficiency and higher productivity for the farmer. Some factors such as soil type can influence the fuel consumption, one of the biggest costs. This study aimed to compare the fuel consumption of a tractor operating in two different conditions of soil in semi-arid regions. The area used for testing is located in the city of Maricopa, in Arizona, belonging to 'The University of Arizona'. The area 1 is classified as sandy clay loam soil (52% sand, 35% clay, 13% silt). The area 2 is classified as a sandy loam soil (71% sand, 12% clay and 17% silt). The tractor 4 x 2 TDA, with 88 kw (120 hp) engine power equipped with auto pilot system and an implement for tillage were used in the experiment. A data acquisition system was installed in the tractor to collect the data generated by the GPS and fuel consumption sensor. The results showed significant statistical difference in fuel consumption between soil textures. (author)

  2. An observation of seasonal and diurnal behavior of O3–NOx relationships and local/regional oxidant (OX = O3 + NO2 levels at a semi-arid urban site of western India

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    Payal Pancholi


    Full Text Available The present study summarizes the continuous measurements of ozone (O3 and oxides of nitrogen (NOx = NO + NO2 along with meteorological conditions in the ambient atmosphere of semi-arid urban site of western India during the year 2012–13. Seasonal and diurnal variations of gaseous pollutants were investigated and compared using the results of time series analysis. The marked seasonal difference was observed for O3 as highest/(lowest during pre-monsoon/(monsoon, respectively. In contrast, NO and NO2 exhibit the highest and lowest levels during post-monsoon and monsoon, respectively. The diurnal cycle of O3 and NOx exhibited inverse relationship where surface O3 showed mid-day peak and lower night-time concentrations. The dataset was used to examine the association of O3 with the ambient levels of NO, NO2 and NOx during day-time and night-time, separately. The variation of an oxidant OX (O3 + NO2 with the levels of NOx was examined to infer the atmospheric sources of OX as sum of NOx-independent regional and NOx-dependent local contributions. Significantly strong positive correlations were observed of O3 with temperature and solar radiation with strong negative correlation with relative humidity during the studied seasons. Inconsiderable difference (< 10 μg m−3 was observed between weekends and weekdays for the levels of O3 during entire observation period.

  3. Fungos anamórficos (Hyphomycetes no Semi-árido do Estado da Bahia, Brasil Anamorphic fungi (Hyphomycetes in the Semi-arid Region of Bahia State, Brazil

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    Flavia Rodrigues Barbosa


    Full Text Available Durante o levantamento de fungos anamórficos associados à folhas em decomposição de diferentes plantas na região semi-árida do Estado da Bahia, 23 espécies, pertencentes a 19 gêneros foram encontradas. Dessas, uma espécie constitui novo registro para a Bahia e três para o Brasil, respectivamente: Drechslera victoriae (F. Meehan & H.C. Murphy Subram. & B.L. Jain, Ochroconis crassihumicola (Matsush. de Hoog & Arx, Pyricularia caffera Matsush. e Tretopileus sphaerophorus (Berk & M.A. Curtis Hughes & Deighton. Descrições, comentários e ilustrações são apresentados para essas espécies.During a survey of the anamorphic fungi associated with leaf litter of different plants from the semi-arid region of Bahia state, 23 species belonging to 19 genera were found. One species is recorded for the first time for Bahia and three for Brazil, respectively: Drechslera victoriae (F. Meehan & H.C. Murphy Subram. & B.L. Jain, Ochroconis crassihumicola (Matsush. de Hoog & Arx, Pyricularia caffera Matsush. and Tretopileus sphaerophorus (Berk & M.A. Curtis Hughes & Deighton. Descriptions, comments and illustrations are provided for these species.

  4. The influence of the climatology of the semi-arid from Alagoas-Brazil on the raw milk microbiota

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    Ticiano Gomes do Nascimento


    Full Text Available This study aimed to evaluate the influence of the climatology of the semi-arid from Alagoas-Brazil on the raw milk microbiota in semi-arid area of the 07 micro-regions of the State of Alagoas of Alagoas, Brazil. The climatic data were extracted from National Institute of Meteorology from the Brazilian government. The raw milk was collected after the dairy cow milking process in 12 small rural associations of the semi-arid from the State of Alagoas, during the 4 seasons and the raw milk was carried out procedures of sampling, transportation and microbiological analysis. A total of 58 samples were counted coliforms at 45°C, Escherichia coli and coagulase-positive Staphylococcus. Only 02 rural associations presented low levels of microbiological contamination, which were located in areas of climatic conditions and parameters of thermal comfort index and vegetation index favorable, but 10 rural associations presented high counting of coliforms at 45°C, Escherichia coli. The climatologic parameters (maximum temperature, atmospheric pressure, bovine comfort thermal index and vegetation index have showed to influence the growth of the coliforms at 45°C and Escherichia coli with high incidence during the summer weather. The precipitation parameter, bovine thermal comfort and vegetation index have displayed to influence coagulase-positive Staphylococcus counting especially during the period between the summer end and the autumn beginning seasons. New Actions, and Rural Education and Health Programs should be implemented as politics of Food Safety. New strategies and programs for dissemination more effective on the risks of transmission of pathogens and Foodborne Diseases are necessary as the part of emergence politics of the health and education areas. Regulatory Actions should be encouraged within the processes that improve the quality control of raw milk as well its bioproducts, with professional assistance relevant in agriculture area.

  5. Dynamics in carbon exchange fluxes for a grazed semi-arid savanna ecosystem in West Africa

    DEFF Research Database (Denmark)

    Tagesson, Torbern; Fensholt, Rasmus; Cropley, Ford


    The main aim of this paper is to study land-atmosphere exchange of carbon dioxide (CO2) for semi-arid savanna ecosystems of the Sahel region and its response to climatic and environmental change. A subsidiary aim is to study and quantify the seasonal dynamics in light use efficiency (ε) being a key...... variable in scaling carbon fluxes from ground observations using earth observation data. The net ecosystem exchange of carbon dioxide (NEE) 2010-2013 was measured using the eddy covariance technique at a grazed semi-arid savanna site in Senegal, West Africa. Night-time NEE was not related to temperature......, confirming that care should be taken before applying temperature response curves for hot dry semi-arid regions when partitioning NEE into gross primary productivity (GPP) and ecosystem respiration (Reco). Partitioning was instead done using light response curves. The values of ε ranged between 0.02g carbon...

  6. Sustainable Small-Scale Agriculture in Semi-Arid Environments

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    Katherine A. Spielmann


    Full Text Available For at least the past 8000 years, small-scale farmers in semi-arid environments have had to mitigate shortfalls in crop production due to variation in precipitation and stream flow. To reduce their vulnerability to a shortfall in their food supply, small-scale farmers developed short-term strategies, including storage and community-scale sharing, to mitigate inter-annual variation in crop production, and long-term strategies, such as migration, to mitigate the effects of sustained droughts. We use the archaeological and paleoclimatic records from A.D. 900-1600 in two regions of the American Southwest to explore the nature of variation in the availability of water for crops, and the strategies that enhanced the resilience of prehistoric agricultural production to climatic variation. Drawing on information concerning contemporary small-scale farming in semi-arid environments, we then suggest that the risk coping and mitigation strategies that have endured for millennia are relevant to enhancing the resilience of contemporary farmers' livelihoods to environmental and economic perturbations.

  7. Development of urbanization in arid and semi arid regions based on the water resource carrying capacity -- a case study of Changji, Xinjiang (United States)

    Xiao, H.; Zhang, L.; Chai, Z.


    The arid and semiarid region in China where have a relatively weak economic foundation, independent development capacity, and the low-level of urbanization. The new urbanization within these regions is facing severe challenges brought by the constraints of resources. In this paper, we selected the Changji Hui Autonomous Prefecture, Xinjiang Uyghur Autonomous Region as study area. We found that agricultural planting structure is the key water consumption index based on the research about the main water demands of domestic, agriculture and industry. Finally, we suggest that more attentions should be paid to the rational utilization of water resources, population carrying capacity, and adjust and upgrade the industrial structure, with the purpose of coordination with the Silk Road Economic Belt.

  8. Guidelines for Establishing Monitoring Programs to Assess the Success of Riparian Restoration Efforts in Arid and Semi-Arid Landscapes (United States)


    ERDC TN-EMRRP-SR-50 1 Guidelines for Establishing Monitoring Programs to Assess the Success of Riparian Restoration Efforts in Arid and Semi ...Management and Restoration Research Program (EMRRP) work unit titled “Techniques for Reestablishing Riparian Hardwoods in Arid and Semi - arid ...Regions.” The objectives of this work are to provide technology to improve capabilities of restoring riparian areas in arid and semi - arid regions. The

  9. Livestock Farming Systems and Cattle Production Orientation in Eastern High Plains of Algeria, Cattle Farming System in Algerian Semi Arid Region


    Lounis Semara; Charefeddine Mouffok; Toufik Madani


    This study was an attempt to devise productive orientations of cattle herds in eastern high plains of Algeria. In this regard, 165 farms randomly identified were investigated. The selection of breeders was based to existence of cattle on the farm, and the farmer proposed to investigation must have at least two cows. The approach taken was to identify all systems adopted by farmers in a region through the analysis of the relationship between the maintenance of different types of cattle and pre...

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

    Energy Technology Data Exchange (ETDEWEB)

    Guentner, A.


    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.)

  11. A regional field-based assessment of organic C sequestration and GHG balances in irrigated agriculture in Mediterranean semi-arid land (United States)

    Virto, Inigo; Antón, Rodrigo; Arias, Nerea; Orcaray, Luis; Enrique, Alberto; Bescansa, Paloma


    In a context of global change and increasing food demand, agriculture faces the challenge of ensuring food security making a sustainable use of resources, especially arable land and water. This implies in many areas a transition towards agricultural systems with increased and stable productivity and a more efficient use of inputs. The introduction of irrigation is, within this framework, a widespread strategy. However, the C cycle and the net GHG emissions can be significantly affected by irrigation. The net effect of this change needs to be quantified at a regional scale. In the region of Navarra (NE Spain) more than 22,300 ha of rainfed agricultural land have been converted to irrigation in the last years, adding to the previous existing irrigated area of 70,000 ha. In this framework the project Life+ Regadiox (LIFE12 ENV/ES/000426, has the objective of evaluating the net GHG balances and atmospheric CO2 fixation rates of different management strategies in irrigated agriculture in the region. The project involved the identification of areas representative of the different pedocllimatic conditions in the region. This required soil and climate characterizations, and the design of a network of agricultural fields representative of the most common dryland and irrigation managements in these areas. This was done from available public datasets on climate and soil, and from soil pits especially sampled for this study. Two areas were then delimited, mostly based on their degree of aridity. Within each of those areas, fields were selected to allow for comparisons at three levels: (i) dryland vs irrigation, (ii) soil and crop management systems for non-permanent crops, and (iii) soil management strategies for permanent crops (namely olive orchards and vineyards). In a second step, the objective of this work was to quantify net SOC variations and GHG balances corresponding to the different managements identified in the previous step. These

  12. Morpho-Physiological Responses of Maize to Drought Stress at Different Growth Stages in Northern Semi-Arid Region of Fars

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    R. Hemati


    Full Text Available In order to evaluate morpho-physiological responses of hybrid corn KSC750 to water stress at various stages of growth, a field experiment was conducted at the Pasargad region (northwest Fars in 2010. The experiment carried out as a randomized complete block design, with 3 replications. In this study, corn growth period was divided into three phases: the establishment of plant to tasseling (phase I, tasseling to dough development (phase II and dough development to ripening (phase III. Treatments were consisted of control, irrigation cut off after dough development, water stress of 75 percent of FC during vegetative phase and after dough development, water stress of 75 percent of FC during whole growth phase, water stress of 50 percent of FC during vegetative stage and after dough development and water stress of 50 percent of FC during whole growth phase. Results showed that mild drought stress (75% FC at vegetative phase was not significantly effected growth and yield of corn. However, application of drought stress during the whole growth period significantly reduced morphological parameters as well as yield and yield components. Based on these results, flowering and grain filling stages were identified as more sensitive stages to drought stress in corn. Moreover, irrigation cut off after dough development terminated to a satisfactory yield. The results indicated that, overall, under Pasargad region and similar agro climatic conditions, it would be possible to save water to 75 percentage of corn water requirement through application of deficit irrigation after dough development stage.

  13. Anatomia de espécies anfíbias de Cyperaceae de lagoas do semi-árido, BA, Brasil Anatomy of amphibious Cyperaceae species from lakes in the semi-arid region of Bahia State, Brazil

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    Kelly Regina Batista Leite


    Full Text Available Foi estudada a anatomia de raízes, rizomas, folhas e escapos de Cyperus odoratus L., Oxycaryum cubense (Poep. & Kunth Lye e Pycreus macrostachyos (Lam. Raynal (Cyperaceae-Poales de lagoas do semi-árido da Bahia visando caracterizar anatomicamente as espécies e levantar estruturas adaptativas à forma de vida anfíbia. As espécies apresentam raízes com epiderme unisseriada, córtex com exoderme e lacunas de ar. Os rizomas apresentam feixes vasculares anfivasais ou colaterais no cilindro vascular. As folhas apresentam epiderme unisseriada, com células de parede periclinal externa mais espessada que a interna, estômatos somente na face abaxial, parênquima clorofiliano alternado com lacunas de ar e feixes vasculares colaterais. Os escapos apresentam epiderme unisseriada, feixes de fibras distribuídos perifericamente alternados com parênquima clorofiliano, lacunas de ar e feixes vasculares colaterais. Oxycaryum cubense difere de Cyperus odoratus e Pycreus macrostachyos por apresentar raízes com pêlos longos, rizomas e estolões com feixes vasculares colaterais, folhas com bordo agudo, e ausência de estrutura Kranz nas folhas e escapos. Características anatômicas como: lacunas de ar observadas principalmente nas raízes, células buliformes na face adaxial da epiderme foliar, hipoderme, reduzido número de elementos xilemáticos e pouca lignificação nas paredes celulares dos tecidos nos diferentes órgãos estudados são consideradas importantes na adaptação dessas plantas anfíbias às lagoas temporárias do semi-árido da Bahia.We examined the anatomy of roots, rhizomes, leaves, and scapes of Cyperus odoratus L., Oxycaryum cubense (Poep. & Kunth Lye, and Pycreus macrostachyos (Lam. Raynal (Cyperaceae-Poales from temporary lakes in the semi-arid region of Bahia in order to characterize the anatomy and examine structural adaptations to amphibious lifestyle. All species had roots with uniseriate epidermal cells, cortex with exoderm

  14. Assessment of soil erosion and conservation on agricultural sloping lands using plot data in the semi-arid hilly loess region of China

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    T.X. Zhu


    New hydrological insights for the region: The results revealed that runoff per unit area slightly increased with slope angle on SSP, but reached a maximum at 15° and then decreased with slope angle on LSP. Soil loss per unit area increased with slope angle on both SSP and LSP. An average of 36.4% less runoff but only 3.6% less soil loss per unit area was produced on LSP than on SSP. The S factor calculated using the slope factor equations in USLE/RUSLE was significantly greater than that estimated from the measured soil loss on the plots. Rainstorms with recurrence intervals greater than 2 years were responsible for more than two thirds of the total soil and water loss. The effectiveness in reducing surface runoff by five types of conservation practices was mixed. However, all the conservation practices yielded much less soil loss than cropland.

  15. Dynamics of Small-Scale Perched Aquifers in the Semi-Arid South-Western Region of Madagascar and Implications for the Sustainable Groundwater Exploitation (United States)

    Englert, A.; Brinkmann, K.; Kobbe, S.; Buerkert, A.


    The south-western region of Madagascar is characterized by limited water resources throughout the year and recurrent droughts, which affect agricultural production and increase the risk of food insecurity. To deliver reliable estimates on the availability and dynamics of water resources, we studied the hydrogeology of several villages in the Mahafaly region. Detailed investigations were conducted for a selected village on a calcareous plateau to predict the local water resources under changing boundary conditions including enhanced water abstraction and changes in groundwater recharge. In 2014 a participatory monitoring network was established, which allowed groundwater level measurements in three wells twice a day. Additional hydrogeological investigations included pumping tests, automatic monitoring of meteorological data, daily groundwater abstraction appraisal and mapping of the spatial extent of the perched aquifer using satellite data. Analysis of the measured data unraveled the aquifer dynamic to be dominated by a groundwater level driven leakage process. The latter is superimposed by groundwater recharge in the rainy season and a daily groundwater abstraction. Based on these findings we developed a model for the aquifer, which allows to predict the duration of groundwater availability as a function of annual precipitation and daily water abstraction. The latter will be implemented in an agent-based land-use model, were groundwater abstraction is a function of population and livestock. The main objective is to model land use scenarios and global trends (climate, market trends and population development) through explicit imbedding of artificial and natural groundwater dynamics. The latter is expected to enable the evaluation of additional water abstraction for agricultural purposes without endangering water supply of the local population and their livestock.

  16. Distribution and diversity of aquatic macroinvertebrate assemblages in a semi-arid region earmarked for shale gas exploration (Eastern Cape Karoo, South Africa.

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    Annah Mabidi

    Full Text Available This study aims to investigate macroinvertebrate assemblage structure and composition across the three major waterbody types (temporary rivers, depression wetlands and semi-permanent dams of the Eastern Cape Karoo, and to identify important environmental and spatial correlates of macroinvertebrate assemblage composition in the region. A total of 33 waterbodies (9 dams, 13 depression wetlands and 11 rivers were sampled. Altogether, 91 taxa were recorded in November 2014 and 82 in April 2015. Twenty-seven taxa were common to all three waterbody types (across both sampling occasions, with 17 of these observed in November and 19 in April. The ANOSIM tests revealed significant differences in assemblage composition between the depression wetlands and rivers for both sampling occasions, but dams did not differ from the other waterbody types. SIMPER analyses indicated that the notonectid Anisops varia and the corixid Micronecta scutellaris were abundant across all three waterbody types during both sampling occasions. The mayfly Cloeon africanum and the damselfly Pseudagrion sp. were abundant in river habitats during both sampling occasions, while the gastropod mollusc Bulinus tropicus and the copepod Lovenula falcifera best characterised depression wetlands on both occasions. Non-metric multidimensional scaling ordination highlighted a clear separation of assemblages between November and April, while distance-based Redundancy Analysis revealed that conductivity, altitude, turbidity and pH were the most important variables explaining the variation in macroinvertebrate assemblage patterns. These results provide baseline information which is important for future biological monitoring of impacts associated with hydraulic fracturing activities and climatic changes in the region.

  17. Utilization of solar electric fence for containment of caprine in familiar production of the Pernambuco semi-arid region; Utilizacao de cerca eletrica solar para confinamento de caprinos na producao familiar do semi-arido pernambucano

    Energy Technology Data Exchange (ETDEWEB)

    Costa, Heitor Scalambrini; Costa Neto, Guilherme [Universidade Federal de Pernambuco (UFPE), Recife, PE (Brazil). Nucleo de Apoio a Projetos de Energias Renovaveis], Email:; Araujo, Kassia; Silva, Gerson Flavio da; Raquel, Karine [ONG NAPER SOLAR, Recife, PE (Brazil). Centro de Estudos e Projetos], Email:


    The Center for Studies and Projects - Naper Solar is an NGO, which works for the dissemination of use of alternative energies resources in the semi-arid Brazilian Northeast in collaboration with the Federal University of Pernambuco. It has implemented caprine raising systems in the back lands of Pajeu in the State of Pernambuco making use of electrified fences energized by solar energy.This project was executed in a joint effort with the City Halls of Afogados da Ingazeira e Sao Jose do Egito and the NGOs Diaconia and the Northeast Woman House and has benefited 20 families of farmers from 9 rural communities. It is funded by a Technical Cooperation Program established between the National Fund for the Environment - Ministry for the Environment and the Netherlands Government. The implemented system, in opposition to the traditional extensive production system, allow for a more animal sanitary control - minimizing the risks of contamination; a more controlled and balanced feeding system - taking into account the weight gaining factor together with pasture management, leading the a guarantee of food supply for the animals. Other advantages of this system include the reduction of fence cost and less deforesting. Electrical fences used in the contention of caprine are built with only 4 straight wires, fixed with isolators on wood posts spaced 10 m from each other, while the conventional fences use 9 barbed-wire lines fixed with clamps on posts spaced 1 m from each other. Therefore, the use of electrical fences instead of the conventional one represent a cost reduction, which can go as high as 40 % of the total cost. Besides that the electrical fences have low maintenance cost, easier and faster installation and relocation. The fenced areas vary from 0.5 ha to 4 ha for the raising of 5 to 50 animals. In the electrification of a fence one needs one photovoltaic module, one electrifier, a battery, isolators (passage and corner), electric ground rods and a thunderbolt

  18. Distribuição da anemia em pré-escolares do semi-árido da Bahia Distribution of anemia among preschool children from the semi-arid region of Bahia

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    Ana Marlúcia O. Assis


    Full Text Available O objetivo desta investigação foi identificar a prevalência da anemia e alguns de seus potenciais determinantes em 754 crianças de áreas urbanas de sete municípios na região do semi-árido baiano. Hemoglobina foi determinada em 745 crianças de um a 72 meses de idade. Para o grupo etário de seis a 72 meses um valor de hemoglobina The objective of this survey was to determine the prevalence of anemia and potential determinants thereof in 754 children from urban areas of seven small towns in the semi-arid region of Bahia. Hemoglobin was measured in 745 children 1 to 72 months of age. For the 6-to-72 month-old group, hemoglobin < 11.0 g/dl was considered anemia (following WHO recommendations whereas <9.5 g/dl was considered severe anemia. The same cutoffs were used for children under 6 months, which are the same ones used in clinical-hematology. A mean hemoglobin of 12.1 g/dl was found, distributed differently according to age groups (p=0.001. The study found prevalences of 22.2 % for anemia and 5.8% for severe anemia, respectively. Occurrence of anemia varied significantly with age (p=0.001; the highest prevalence was 50.0% in children 12 to 23 months of age, followed by 29.9% in children below 12 months. The association of anemia with mother's education (controlled for age and per capita family income was not statistically significant.

  19. Interannual variability of a precipitation gradient along the semi-arid catchment areas for the metropolitan region of Lima- Peru in relation to atmospheric circulation at the mesoscale (United States)

    Otto, Marco; Seidel, Jochen; Trachte, Katja


    The main moisture source for precipitation on the western slopes of the Central Andes is located east of the mountain range known as the Amazon basin. However, the Andean mountains, which reach up to 6000 m a.s.l., strongly influence climatic conditions along the Pacific coastline of South America as a climatic barrier for the low-level tropospheric flow and associated moisture transport from the Amazon basin. Additional, large scale subsidence caused by the South Pacific High inhabits convective rainfall at the Pacific coast where large metropolitan areas such as the Peruvian capital Lima are located. Two contrasts in precipitation can be found while crossing the Andean mountains from West to East. On the Pacific coast, at the location of the metropolitan area of Lima, no more than 10 mm mean annual rainfall occurs. In contrast, up to 1000 mm mean annual rainfall occur only 100 km east of Lima within the upper region (4000 m .a.s.l.) of the Western Cordillera. The transition takes place along the western slopes of the Western Cordillera and is characterised by a strong precipitation gradient. Here, catchment areas are located that provide most of the water resources needed to sustain an urban area of approximately 10 million people. This study investigates the interannual variability of the precipitation gradient between 1998 and 2012. The analysis is based on daily precipitation data of 22 rain gauge station, daily rainfall data of the Tropical Rainfall Mission (TRMM 3B42) at 0.25 degrees and reanalysis data at 36 km spatial resolution at the mesoscale. The reanalysis data was produced using the Weather Research and Forecasting Model. Station data was provided by the Peruvian weather service during the project "Sustainable Water and Wastewater Management in Urban Growth Centres Coping with Climate Change - Concepts for Lima Metropolitana (Peru) (LiWa)", which is financed by the German Federal Ministry of Education and Research (BMBF). We are interested in the

  20. Wild flora of mine tailings: perspectives for use in phytoremediation of potentially toxic elements in a semi-arid region in Mexico. (United States)

    Sánchez-López, Ariadna S; Del Carmen A González-Chávez, Ma; Carrillo-González, Rogelio; Vangronsveld, Jaco; Díaz-Garduño, Margarita


    The aim of this research was to identify wild plant species applicable for remediation of mine tailings in arid soils. Plants growing on two mine tailings were identified and evaluated for their potential use in phytoremediation based on the concentration of potentially toxic elements (PTEs) in roots and shoots, bioconcentration (BCF) and translocation factors (TF). Total, water-soluble and DTPA-extractable concentrations of Pb, Cd, Zn, Cu, Co and Ni in rhizospheric and bulk soil were determined. Twelve species can grow on mine tailings, accumulate PTEs concentrations above the commonly accepted phytotoxicity levels, and are suitable for establishing a vegetation cover on barren mine tailings in the Zimapan region. Pteridium sp. is suitable for Zn and Cd phytostabilization. Aster gymnocephalus is a potential phytoextractor for Zn, Cd, Pb and Cu; Gnaphalium sp. for Cu and Crotalaria pumila for Zn. The species play different roles according to the specific conditions where they are growing at one site behaving as a PTEs accumulator and at another as a stabilizer. For this reason and due to the lack of a unified approach for calculation and interpretation of bioaccumulation factors, only considering BCF and TF may be not practical in all cases.

  1. Birds and fish as bioindicators of tourist disturbance in springs in semi-arid regions in Mexico: a basis for management

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    Palacio-Núñez, J.


    Full Text Available Tourist disturbance in semi–arid springs was analysed; birds and fish were selected as bioindicators. Media Luna spring is the biggest and most spatially complex system in the region, with the highest biodiversity levels and tourist use. Areas with the highest bird species richness and abundances showed highest structural heterogeneity and least direct human impact. No differences in species richness of fish were observed between sectors and the most abundant species were found in the sectors least perturbed by human activity. Factors that explained the bird distribution were the species´ tolerance to the effects of direct tourism (noise and direct presence of people and habitat quality, mainly riparian vegetation. Aquatic vegetation condition was very important for fish. Six bird species and two fish species were relevant as indicators of the habitat quality related to human impact. Anthropic disturbance such as tree plantation favoured some bird species, whereas aquatic vegetation removal was favourable for some fish species, such as the endemic Cichlasoma bartoni, however, both types of disturbance were unfavourable for other species; riparian vegetation removal was negative for both groups. Controlled tourism promotes good conditions for C. bartoni establishment. Efficient conservation measures such as limiting touristic distribution are necessary for all species, especially for the fish community, in order to conserve biodiversity in general.

  2. Dryland salinity: threatening water resources in the semi-arid Western Cape

    CSIR Research Space (South Africa)

    Bugan, Richard DH


    Full Text Available : THREATENING WATER RESOURCES IN THE SEMI-ARID WESTERN CAPE Increased dryland salinity in the Swartland and Overberg regions poses a threat to the bread basket of the Western Cape, water resources in an already water-stressed area, water supply... an increase in salt concentrations, particularly in the mid- to lower reaches of the river, thereby impacting on drinking water quality and agriculture. Dryland salinity poses a major threat to water quality, particularly in semi-arid areas. It is usually...

  3. Remote sensing for mapping soil moisture and drainage potential in semi-arid regions: Applications to the Campidano plain of Sardinia, Italy. (United States)

    Filion, Rébecca; Bernier, Monique; Paniconi, Claudio; Chokmani, Karem; Melis, Massimo; Soddu, Antonino; Talazac, Manon; Lafortune, Francois-Xavier


    The aim of this study is to investigate the potential of radar (ENVISAT ASAR and RADARSAT-2) and LANDSAT data to generate reliable soil moisture maps to support water management and agricultural practice in Mediterranean regions, particularly during dry seasons. The study is based on extensive field surveys conducted from 2005 to 2009 in the Campidano plain of Sardinia, Italy. A total of 12 small bare soil fields were sampled for moisture, surface roughness, and texture values. From field scale analysis with ENVISAT ASAR (C-band, VV polarized, descending mode, incidence angle from 15.0° to 31.4°), an empirical model for estimating bare soil moisture was established, with a coefficient of determination (R(2)) of 0.85. LANDSAT TM5 images were also used for soil moisture estimation using the TVX slope (temperature/vegetation index), and in this case the best linear relationship had an R(2) of 0.81. A cross-validation on the two empirical models demonstrated the potential of C-band SAR data for estimation of surface moisture, with and R(2) of 0.76 (bias +0.3% and RMSE 7%) for ENVISAT ASAR and 0.54 (bias +1.3% and RMSE 5%) for LANDSAT TM5. The two models developed at plot level were then applied over the Campidano plain and assessed via multitemporal and spatial analyses, in the latter case against soil permeability data from a pedological map of Sardinia. Encouraging estimated soil moisture (ESM) maps were obtained for the SAR-based model, whereas the LANDSAT-based model would require a better field data set for validation, including ground data collected on vegetated fields. ESM maps showed sensitivity to soil drainage qualities or drainage potential, which could be useful in irrigation management and other agricultural applications. Copyright © 2015 Elsevier B.V. All rights reserved.

  4. Benefits from using combined dynamical-statistical downscaling approaches in building crop water demand scenarios in a semi-arid Mediterranean region. (United States)

    Guyennon, Nicolas; Portoghese, Ivan; Romano, Emanuele; Calmanti, Sandro


    Various downscaling techniques have been developed to bridge the scale gap between global climate models (GCMs) and finer scales required to assess hydrological impacts of climate change. Although statistical downscaling (SD) has been traditionally seen as an alternative to dynamical downscaling (DD), recent works on statistical downscaling have aimed to combine the benefits of these two approaches. The overall objective of this study is to assess whether a DD processing performed before the SD permits to obtain more suitable scenarios of crop water demand. The case study presented here focuses on the north-western part of the Apulia region named Capitanata plain (South East of Italy, surface area about 4000 km2), dominated by agriculture (about 15% of the national production of cereals and olive trees) and mainly depending on surface water. The fifth-generation ECHAM model from the Max-Planck-Institute for Meteorology was adopted as GCM. The DD was carried out with the Protheus system (ENEA), while the SD was performed through a monthly quantile-quantile correction. Finally the crop water demand is estimated through the water mass-balance model G-MAP, considering monthly precipitation, monthly temperature and the major landscape features that determine the soil water balance. The latter introduces a strong non linearity with respect to the meteorological input, due to the non-linear solution of soil infiltration and moisture-dependent evapotranspiration and the threshold-based runoff mechanism, which prevents from forecasting the crop water demand as simple linear combination of the precipitation and temperature scenarios. The crop water demand scenarios resulting from the different downscaling and their combination are then compared in terms of bias, long term non stationarity and spatial variability.

  5. Use and management of Mimosa species in the Tehuacán-Cuicatlán Valley, a tropical semi-arid region in Mexico (Fabaceae-Mimosoideae

    Directory of Open Access Journals (Sweden)

    S.L Camargo-Ricalde


    Full Text Available We report on the use of 15 Mimosa species within the Tehucán-Cuicatlán Valley,south-central Mexico.Seven of these species are endemic to Mexico,and four species and one variety are endemic to the Valley.We reviewed historical,ethnobotanical and floristic manuscripts,and conducted field studies.Several herbaria were consulted,as well as the BADEPLAM data base.Field work in the Valley has been done from 1994 to date.Most of the Mimosa species occur in the arid tropical scrub and the tropical deciduous forest,which are considered the most endangered vegetation types of the Valley.Our findings show that Mimosa species are used as fodder (45%,fuel (31%,living fences (14%and construction material (7%.Only one species is used as medicine.Mimosa species are "multipurpose "shrubs/trees of the agrosilvopastoral system of this region.Rev. Biol.Trop.52(4:845-851.Epub 2005 Jun 24.En este trabajo se informa el uso de 15 especies del género Mimosa dentro de la Reserva de la Biósfera del Valle de Tehuacán-Cuicatlán,en la región centro-sur de México.De las 15 especies de Mimosa estudiadas,siete de ellas son endémicas de México y cuatro especies y una variedad son endémicas del Valle.Se revisaron manuscritos y documentos históricos,etnobotánicos y florísticos,y se llevó a cabo trabajo de campo.Se consultaron varios herbarios,así como la base de datos BADEPLAM.El trabajo de campo en el Valle se está realizando desde 1994 hasta la fecha.La mayoría de las especies de Mimosa se establecen en el matorral xerófilo,el cual está considerado como el tipo de vegetación que está más en peligro de todos los que se encuentran en la Reserva.Los resultados muestran que la mayoría de las especies de Mimosa se usan como forraje (45%y como combustible (31%,así como en la formación de cercas vivas (14%y como material para construcción (7%;mientras que sólo una especie presenta un uso medicinal.Las especies de Mimosa son arbustos y/o árboles "multiprop

  6. Canola integration into semi-arid wheat cropping systems of the inland Pacific Northwestern USA (United States)

    The inland Pacific Northwestern USA (iPNW) wheat-producing region has a diversity of environments and soils, yet it lacks crop diversity and is one of the few semi-arid wheat-growing regions without significant integration of oilseeds. Four major agroecological zones, primarily characterised by wate...

  7. Modelling annual evapotranspiration in a semi-arid, African savanna ...

    African Journals Online (AJOL)

    Modelling annual evapotranspiration in a semi-arid, African savanna: functional convergence theory, MODIS LAI and the Penman–Monteith equation. ... and, when used independently of the eddy covariance data, ETMODIS predicted an annual ET of 378 mm in 2007 for the semi-arid savanna around the Skukuza flux site.

  8. Vegetation pattern formation in semi-arid grazing systems

    NARCIS (Netherlands)

    HillerisLambers, R.; Rietkerk, M.G.; Bosch, F. van den; Prins, H.H.T.; Kroon, H. de


    Hypotheses about the origin of vegetation pattern formation in semi-arid areas around the world almost all include a common feature of semi-arid areas: the presence of a positive feedback between plant density and water infiltration. We investigate whether this positive feedback and the spatial

  9. Characterisation of rainfall at a semi-arid ecotope in the Limpopo ...

    African Journals Online (AJOL)

    Despite the importance of rain-fed agriculture to food security in the semi-arid regions of South Africa, studies to understand the spatial and temporal variability of rainfall are not widely documented. Twenty-three years (1983 to 2005) of rainfall data were analysed in order to study the basic statistical rainfall characteristics at ...

  10. Energy Balance and Heat Storage of Small Shallow Water Bodies in Semi-arid Areas

    NARCIS (Netherlands)

    Abbasi, A.


    This research aims at developing a flexible and efficient (numerical) approach for estimating energy balance and heat storage of small shallow lakes in arid and semi-arid regions. To reach to this aim, some numerical methods and improvements in conventional methods were done. Optimizing the methods

  11. Assessment of Reservoir Storage in a Semi-Arid Environment Using ...

    African Journals Online (AJOL)

    Nekky Umera

    There was also clear indication of climatic change within the region as rainfall of North Central and ... probability matrix to 156 Australian streams but modified the Gould. Probability procedure and estimated the ... The climate of the area was a semi-arid, tropical climate dominated by the tropical maritime air mass which ...

  12. Effects of irrigation and plastic mulch on soil properties on semi-arid abandoned fields

    NARCIS (Netherlands)

    van der Meulen, E.S.; Nol, L.; Cammeraat, L.H.


    The Guadalentín Basin in Spain is one of the driest areas of Europe and has problems with high evaporation rates, and high risks of desertification exist including soil quality loss and soil erosion. Farmers in this semi-arid region use polyethylene covers on their irrigated croplands to reduce

  13. Adaptation of agriculture to climate change in semi-arid Borena, Ethiopia

    NARCIS (Netherlands)

    Ng'ang'a, Stanley; Wijk, van Mark T.; Rufino, Mariana C.; Giller, Ken E.


    Livestock production is very risky due to climate variability in semi-arid Sub-Saharan Africa. Using data collected from 400 households in the Borena zone of the Oromia Region, we explored what drives adoption of agricultural practices that can decrease the vulnerability of agro-pastoralists to

  14. Modeling Sediment Yield in Semi-Arid Pasture Micro-Catchments, NW Iran

    NARCIS (Netherlands)

    Vaezi, Ali Reza; Abbasi, Mohammad; Bussi, Gianbattista; Keesstra, Saskia


    Modeling sediment yield is a complex task because of the nonlinearity of natural processes intervening at slope and basin scale. In this study slope steepness, vegetation cover, and soil properties along with sediment yield were studied in 20 pasture micro-catchments in a semi-arid region, NW Iran

  15. Precision farming for increased land and labour productivity in semi-arid West Africa. A review

    NARCIS (Netherlands)

    Aune, Jens B.; Coulibaly, Adama; Giller, Ken E.


    Farmers in the semi-arid regions of West Africa face challenges related to poor crop establishment, variable rainfall, low soil fertility and a shortage of labour at times of peak demand. Farmers are generally low on resources. Given these conditions, it is important to develop farming practices

  16. Evaluation of small scale water harvesting techniques for semi-arid environments

    NARCIS (Netherlands)

    Lasage, R.; Verburg, P.H.


    Water harvesting is widely practiced and is expected to improve water availability for domestic and agricultural use in semi-arid regions. New funds are becoming available to stimulate the implementation of water harvesting projects. We review the literature to gain insight regarding characteristics

  17. Preface paper to the Semi-Arid Land-Surface-Atmosphere (SALSA) Program special issue (United States)

    Goodrich, D.C.; Chehbouni, A.; Goff, B.; MacNish, B.; Maddock, T.; Moran, S.; Shuttleworth, W.J.; Williams, D.G.; Watts, C.; Hipps, L.H.; Cooper, D.I.; Schieldge, J.; Kerr, Y.H.; Arias, H.; Kirkland, M.; Carlos, R.; Cayrol, P.; Kepner, W.; Jones, B.; Avissar, R.; Begue, A.; Bonnefond, J.-M.; Boulet, G.; Branan, B.; Brunel, J.P.; Chen, L.C.; Clarke, T.; Davis, M.R.; DeBruin, H.; Dedieu, G.; Elguero, E.; Eichinger, W.E.; Everitt, J.; Garatuza-Payan, J.; Gempko, V.L.; Gupta, H.; Harlow, C.; Hartogensis, O.; Helfert, M.; Holifield, C.; Hymer, D.; Kahle, A.; Keefer, T.; Krishnamoorthy, S.; Lhomme, J.-P.; Lagouarde, J.-P.; Lo, Seen D.; Luquet, D.; Marsett, R.; Monteny, B.; Ni, W.; Nouvellon, Y.; Pinker, R.; Peters, C.; Pool, D.; Qi, J.; Rambal, S.; Rodriguez, J.; Santiago, F.; Sano, E.; Schaeffer, S.M.; Schulte, M.; Scott, R.; Shao, X.; Snyder, K.A.; Sorooshian, S.; Unkrich, C.L.; Whitaker, M.; Yucel, I.


    The Semi-Arid Land-Surface-Atmosphere Program (SALSA) is a multi-agency, multi-national research effort that seeks to evaluate the consequences of natural and human-induced environmental change in semi-arid regions. The ultimate goal of SALSA is to advance scientific understanding of the semi-arid portion of the hydrosphere-biosphere interface in order to provide reliable information for environmental decision making. SALSA approaches this goal through a program of long-term, integrated observations, process research, modeling, assessment, and information management that is sustained by cooperation among scientists and information users. In this preface to the SALSA special issue, general program background information and the critical nature of semi-arid regions is presented. A brief description of the Upper San Pedro River Basin, the initial location for focused SALSA research follows. Several overarching research objectives under which much of the interdisciplinary research contained in the special issue was undertaken are discussed. Principal methods, primary research sites and data collection used by numerous investigators during 1997-1999 are then presented. Scientists from about 20 US, five European (four French and one Dutch), and three Mexican agencies and institutions have collaborated closely to make the research leading to this special issue a reality. The SALSA Program has served as a model of interagency cooperation by breaking new ground in the approach to large scale interdisciplinary science with relatively limited resources.

  18. Permafrost distribution modelling in the semi-arid Chilean Andes

    National Research Council Canada - National Science Library

    Azócar, Guillermo F; Brenning, Alexander; Bodin, Xavier


    ...; this kind of model approach has never been applied for a large portion of the Andes. In the present study, this methodology is applied to map permafrost favourability throughout the semi-arid Andes of central Chile (29–32...

  19. Impact of sustained drought on a semi-arid Colophospermum ...

    African Journals Online (AJOL)

    Keywords: botany; Colophospermum mopane; composition change; drought; impact; mopane; Mopani Veld; mortality; Northern Province; perennial grass; recruitment; savanna; semi-arid; South Africa; vegetation changes; abundance; browsing; browsing pressure; combretum apiculatum; condition; decline; dominance; ...

  20. Bró, caxixe e ouricuri estratégias de sobrevivência no semi-árido baiano "Bró", chayote and uricury syagrus palm strategies of survival in the semi-arid region of Bahia, Brazil

    Directory of Open Access Journals (Sweden)

    Ana Marlúcia Oliveira Assis


    Full Text Available Trata-se de um estudo etnográfico desenvolvido no contexto do Projeto Cansanção - PROCAN - realizado no período de 1987 a 1990. Analisa-se um conjunto de informações sobre os padrões culturais que cercam o ato alimentar dos grupos sociais que habitam Cansanção, região do semi-árido baiano. Foram investigados modelos de alimentação, a partir de depoimentos das mulheres trabalhadoras rurais, observando-se as estratégias de sobrevivência alimentar, enquanto ações concretas com vistas a assegurar a reprodução da unidade familiar. O medo da proximidade da doença e da morte são referências fundamentais como modos de conceber a vida e de definições de hábitos alimentares, apoiadas pela compreensão particular de seus próprios mundos. Os hábitos que cercam o ato alimentar em Cansanção indicam uma relação entre a sobrevivência do corpo e a reprodução da unidade familiar, permeados pelo cotidiano da seca. A atividade central, o trabalho da roça, subordinado às condições precárias de vida permite a produção e reprodução de formas de conceber a vida, e em particular, define os vários conceitos e classificações sobre as necessidades de alimentar o corpo. Em algumas áreas do município de Cansanção, observa-se um modo de conceber o alimento a partir de uma razão subordinada a valores do comércio, mas o fenômeno da seca constitui ainda o determinante da cultura alimentar da população e de suas ações concretas para solucionar a carência alimentar no grupo familiar.This study was developed within the context of the project Cansanção - PROCAN- developed by the Federal University of Bahia, Brazil. The study analyzed information concerning cultural patterns which surround the eating habits of the social groups which live in the semi-arid region of Bahia. It is an ethnographic study carried out over the period of 1987 to 1990. The subject of the investigation was the cultural aspect of eating habits of

  1. Requerimento hídrico e coeficiente de cultura da cana-de-açúcar irrigada no semiárido brasileiro Water requirement and crop coefficient of irrigated sugarcane in a semi-arid region

    Directory of Open Access Journals (Sweden)

    Thieres G. F. da Silva


    Full Text Available O objetivo deste trabalho foi determinar o requerimento hídrico e o coeficiente de cultura (Kc da cana-de-açúcar irrigada durante o ciclo de soca, variedade RB 92-579, na região semiárida do Submédio do Vale do São Francisco. O experimento foi conduzido em área de cultivo comercial de cana-de-açúcar situada no município de Juazeiro, BA. Obteve-se o requerimento hídrico da cultura por meio do método do Balanço de Energia Razão de Bowen. Foram monitoradas também a biomassa acumulada e a fração da radiação fotossinteticamente ativa interceptada pela cultura (fRFA. Com os resultados constatou-se que a evapotranspiração da cana-de-açúcar atingiu uma taxa média diária de 4,7 mm, em resposta ao acúmulo de biomassa e, mas a fRFA apresentou, entretanto, influência do tombamento da cultura durante a fase de crescimento máximo. O requerimento hídrico total da cana-de-açúcar foi de 1710 mm, e o Kc atingiu o valor médio de 1,10 na fase de crescimento máximo. As equações de estimativa do Kc mensal, tendo graus dias acumulados e dias após o corte como variáveis independentes apresentaram ótimos ajustes (R2 ~ 0,95 e 0,98 e consideram a redução nos valores de Kc devida ao tombamento da cultura.The objective of this study was to determine the water requirement and crop coefficient of the irrigated sugarcane, variety RB 92-579, in the semi-arid region of the lower middle of São Francisco Valley. The experiment was carried out in a commercial area of sugarcane located in the municipality of Juazeiro in the State of Bahia. The crop water requirement was estimated with the Bowen Ratio Energy Balance method. The accumulated biomass and the photosynthetic active radiation intercepted (fPAR by the crop were monitored. The sugarcane evapotranspiration reached a mean value of 4.7 mm d-1 in response to fPAR and accumulated biomass; however presented influence of the crop lodging during the maximum growth phase. The total water

  2. Parâmetros de rugosidade aerodinâmica sobre vegetação esparsa em região semi-árida Aerodynamic roughness parameters over sparse vegetation in a semi-arid region

    Directory of Open Access Journals (Sweden)

    Gustavo Bastos Lyra


    Full Text Available Utilizando observações micrometeorológicas e da estrutura física da vegetação do experimento HAPEX-Sahel foi possível avaliar alguns métodos para determinar o comprimento de rugosidade (z0 e o deslocamento do plano zero (d. Propõe-se também uma alternativa para estimar esses parâmetros em escoamentos atmosféricos sobre vegetação esparsa em região semi-árida. O método proposto combinou o perfil logarítmico do vento com z0 = lambda (h - d, em que, h é a altura da vegetação e lambda depende de sua estrutura física. Valores de lambda foram estimados em função da estrutura física da vegetação ou obtido na literatura. A altura média da vegetação era 2,06 (± 0,47 m. O perfil do vento foi caracterizado por medidas a quatro níveis acima da superfície (3,0; 4,1; 5,3 e 8,5 m, com a velocidade de fricção (u* determinada por correlações dos turbilhões a 9 m. O método proposto estimou adequadamente a rugosidade aerodinâmica da superfície com lambda = 0,188 e 0,190, determinados pela estrutura da vegetação local, o que não ocorreu para lambda = 0,166, da literatura. Os parâmetros de rugosidade determinados pelos métodos que utilizam u* na solução da lei logarítmica do vento descreveram melhor a rugosidade da superfície. Nos períodos de observações a rugosidade da área foi descrita satisfatoriamente por d = 0,95 m = 0,46 h e z0 = 0,204 m = 0,1 h.Using micrometeorological observations and the physical structure of the vegetation during the HAPEX-Sahel experiment it was possible to evaluate some methods to determine the roughness length (z0 and the zero-plane displacement (d. It is also proposed an alternative to estimate such parameters for the atmospheric flow over sparse vegetation in a semi-arid region. It combines the wind logarithmic profile with z0 = lambda (h - d, where, h is the vegetation height, and lambda is a coefficient determined by the physical structure of the vegetation. Here, lambda values

  3. Seasonal response of edaphic bioindicators using green manure in Brazilian semi-arid conditions Sazonalidade de resposta de bioindicadores edáficos utilizando adubação verde no semi-árido brasileiro

    Directory of Open Access Journals (Sweden)

    Márcio Sampaio Pimentel


    Full Text Available The goal of this work was to evaluate the response of edaphic macrofauna, soil microbial biomass carbon, soil basal respiration, metabolic quotient and labile carbon of fumigated soil in a Fluvic Neosol. The experimental design was in randomized blocks, with five treatments (four green manure mix and one control and four replications, and subsequent planting of melon (Cucumis melo L. under semi-arid conditions in Juazeiro, Bahia State, Brazil, from August 2006 to August 2007. Soil samples were collected at a depth of 0-10 cm at 6 days before, and 117; 215 and 354 days after green manure mix planting. The results indicate that none of the attributes presented a significant difference for the treatments, but changed significantly in relation to the time of sample collection. The higher levels of soil microbial biomass carbon and labile carbon of fumigated soil were measured 117 days after planting. Soil microbial biomass carbon was inversely correlated with soil basal respiration and metabolic quotient, which increased as of 215 days after planting. At 354 days after planting, the edaphic macrofauna presented the highest density, richness, diversity and uniformity. Ants and beetles were most abundant in the areas studied.O objetivo deste trabalho foi avaliar a resposta da macrofauna edáfica, carbono da biomassa microbiana, respiração do solo, quociente metabólico e carbono lábil de solo fumigado em Neossolo Flúvico. O delineamento experimental foi em locos ao acaso com cinco tratamentos (quatro combinações de coquetéis vegetais e testemunha e quatro repetições, e subseqüente plantio de melão na região semi-árida de Juazeiro, Bahia, Brasil, entre os meses de agosto de 2006 a agosto de 2007. Foram realizadas quatro coletas de solo na profundidade de 0-10 cm aos: seis dias antes do plantio do coquetel vegetal, 117; 215 e 354 dias após plantio do coquetel vegetal. Os resultados obtidos indicam que todos os atributos não apresentaram

  4. Using NDVI to measure precipitation in semi-arid landscapes (United States)

    Birtwhistle, Amy N.; Laituri, Melinda; Bledsoe, Brian; Friedman, Jonathan M.


    Measuring precipitation in semi-arid landscapes is important for understanding the processes related to rainfall and run-off; however, measuring precipitation accurately can often be challenging especially within remote regions where precipitation instruments are scarce. Typically, rain-gauges are sparsely distributed and research comparing rain-gauge and RADAR precipitation estimates reveal that RADAR data are often misleading, especially for monsoon season convective storms. This study investigates an alternative way to map the spatial and temporal variation of precipitation inputs along ephemeral stream channels using Normalized Difference Vegetation Index (NDVI) derived from Landsat Thematic Mapper imagery. NDVI values from 26 years of pre- and post-monsoon season Landsat imagery were derived across Yuma Proving Ground (YPG), a region covering 3,367 km2 of semiarid landscapes in southwestern Arizona, USA. The change in NDVI from a pre-to post-monsoon season image along ephemeral stream channels explained 73% of the variance in annual monsoonal precipitation totals from a nearby rain-gauge. In addition, large seasonal changes in NDVI along channels were useful in determining when and where flow events have occurred.

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

    Energy Technology Data Exchange (ETDEWEB)

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


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

  6. Intra-seasonal NDVI change projections in semi-arid Africa (United States)

    Funk, Christopher C.; Brown, Molly E.


    Early warning systems (EWS) tend to focus on the identification of slow onset disasters such famine and epidemic disease. Since hazardous environmental conditions often precede disastrous outcomes by many months, effective monitoring via satellite and in situ observations can successfully guide mitigation activities. Accurate short term forecasts of NDVI could increase lead times, making early warning earlier. This paper presents a simple empirical model for making 1 to 4 month NDVI projections. These statistical projections are based on parameterized satellite rainfall estimates (RFE) and relative humidity demand (RHD). A quasi-global, 1 month ahead, 1° study demonstrates reasonable accuracies in many semi-arid regions. In Africa, a 0.1° cross-validated skill assessment quantifies the technique's applicability at 1 to 4 month forecast intervals. These results suggest that useful projections can be made over many semi-arid, food insecure regions of Africa, with plausible extensions to drought prone areas of Asia, Australia and South America.

  7. Greenhouse Gases Emission and Potential Carbon Sequestration: A Case Study of Semi-arid Area in South India


    K Lenin Babu; Raju, K. V.


    Global warming and climate change have made adoption measures essential, more so in semi arid regions. Kolar district is typical of semi arid regions with a low Development Index in Karnataka State. Greenhouse gases emissions from various sectors are in tune of 2717 kilotons, however, with a significant potential in the district for Carbon Emission Reduction (15,572 tCO2) and carbon Sequestration measures (3,508,010 tons CO2e) under Kyoto Protocol. If developed, revenues from these measures c...

  8. Integrated catchment modelling in a Semi-arid area

    CSIR Research Space (South Africa)

    Bugan, Richard DH


    Full Text Available optimization, statistical and sensitivity analyses are also included in the model. exAMple oF ApplIcAtIon the J2000 process model was applied to the Sandspruit seasonal tributary of the Berg river, in the semi-arid climate (300-400 mm a-1 precipitation... Catchment Modelling in a Semi-arid Area RDH BUGAN AND NZ JOVANOVIC CSIR Natural Resources and the Environment, PO Box 320, Stellenbosch, 7599, South Africa Email: – IntroductIon Water management in South Africa...

  9. Estratégias de Gestão da Água em Situação de Escassez: Regiões Semiáridas e Mediterrânicas Water management strategies in a scarcity situation: Semi-arid and Mediterranean regions

    Directory of Open Access Journals (Sweden)

    Joana Rosado


    Full Text Available No início do século XXI a escassez da água é inquestionável constituindo uma ameaça para a humanidade e para a biosfera. Esta situação é sentida nas regiões Áridas, Semiáridas e Mediterrânicas. A gestão dos recursos aquáticos e da disponibilidade de água é um tema complexo e de uma enorme importância estratégica para o desenvolvimento sustentável. O principal objectivo deste trabalho é apresentar e discutir estratégias de gestão da água em regiões Semiáridas e Mediterrânicas através da revisão da literatura disponível. Conclui-se que as regiões Semiáridas, devido às suas características específicas, sofrerão mais com a escassez. Relativamente ao Mediterrâneo, todos os cenários de evolução futura prevêem uma diminuição da precipitação, tendência que trará graves impactes em termos sociais e ambientais. Interessará às regiões Mediterrânicas implementar as técnicas simples e de baixo custo utilizadas nas regiões Semiáridas, muitas das quais presentemente abandonadas mas com tradições centenárias na história do Mediterrâneo.At the beginning of the 21st century, the shortage of water is unquestionable constituting a threat to humanity and the biosphere. This situation is experienced in arid, Semi-arid and Mediterranean regions. The management of aquatic resources and the availability of water is a complex issue and of a huge strategic importance for sustainable development. The main objective of this paper is to present and discuss strategies for water management in the Mediterranean and Semi-arid regions through a literature review. As a conclusion, the semi-arid regions, due to its specific characteristics, will suffer more with water scarcity. Regarding the Mediterranean, all scenarios of future developments foresee a decline in rainfall, a trend which will bring serious impacts on society and environment. Hence, Mediterranean regions should focus in implementing simple techniques and

  10. Effects of fishing technique on assessing species composition in aquatic systems in semi-arid Brazil

    Directory of Open Access Journals (Sweden)

    ESF Medeiros

    Full Text Available In most ecological field research, appropriate sampling is critical for the understanding of processes underlying fish populations and communities, and is even more important in heterogeneous environments such as the aquatic systems of the semi-arid region of Brazil. This study intends to make a contribution to the development of sampling programs and gear selection in aquatic systems of semi-arid Brazil by evaluating the effects of different fishing techniques on the assessment of richness and composition of the fish fauna in selected aquatic environments. Six sites were selected to represent typical artificial (reservoirs and natural (intermittent streams environments and four different types of sampling gear were applied to each site during four occasions. The present study shows that when selecting sampling techniques to be used in aquatic systems in semi-arid Brazil, one must consider the objectives of the study, e.g. ecological or taxonomic, in order to decide on inclusion of rare species in the sampling population. Also, the effect of the sampling gear on natural abundances of fish must be considered given that some sampling techniques are highly detrimental to fish population numbers.

  11. Coprophilous Mucorales (ex Zygomycota) from three areas in the semi-arid of Pernambuco, Brazil. (United States)

    Souza, Carlos Alberto Fragoso de; Lima, Diogo Xavier; Gurgel, Luciana M S; Santiago, André Luiz Cabral Monteiro de Azevedo

    Mucorales comprises fungi commonly isolated as saprobes from soil, dung, stored grains and plants. Although these fungi have been studied in several countries, there are relatively a few reports of them in semi-arid areas. Therefore, the aims of the present study were to assess and compare the Mucorales communities in dung from different species and breeds of herbivores in the semi-arid of Pernambuco, based on the frequency of occurrence and species richness of these fungi. Samples of dung collected in the cities of Arcoverde, Serra Talhada and Sertânia were incubated in moist chambers in triplicate. Altogether, 24 taxa of Mucorales distributed in the genera Absidia, Circinella, Cunninghamella, Lichtheimia, Mucor, Pilobolus, Rhizopus and Syncephalastrum were identified. The highest species richness was found in sheep excrement. Mucor circinelloides f. griseo-cyanus was the most common taxon, followed by M. ramosissimus. The similarity of the composition of Mucorales species was greatest between the excrements of Guzerá and Sindi breeds (bovine). All mucoralean species isolated are being cited for the first time from animal dung found in Caatinga and a new species of Mucor was recorded. An identification key for species of Mucorales from dung in the semi-arid region of Brazil is provided. Copyright © 2016 Sociedade Brasileira de Microbiologia. Published by Elsevier Editora Ltda. All rights reserved.

  12. Coprophilous Mucorales (ex Zygomycota from three areas in the semi-arid of Pernambuco, Brazil

    Directory of Open Access Journals (Sweden)

    Carlos Alberto Fragoso de Souza

    Full Text Available Abstract Mucorales comprises fungi commonly isolated as saprobes from soil, dung, stored grains and plants. Although these fungi have been studied in several countries, there are relatively a few reports of them in semi-arid areas. Therefore, the aims of the present study were to assess and compare the Mucorales communities in dung from different species and breeds of herbivores in the semi-arid of Pernambuco, based on the frequency of occurrence and species richness of these fungi. Samples of dung collected in the cities of Arcoverde, Serra Talhada and Sertânia were incubated in moist chambers in triplicate. Altogether, 24 taxa of Mucorales distributed in the genera Absidia, Circinella, Cunninghamella, Lichtheimia, Mucor, Pilobolus, Rhizopus and Syncephalastrum were identified. The highest species richness was found in sheep excrement. Mucor circinelloides f. griseo-cyanus was the most common taxon, followed by M. ramosissimus. The similarity of the composition of Mucorales species was greatest between the excrements of Guzerá and Sindi breeds (bovine. All mucoralean species isolated are being cited for the first time from animal dung found in Caatinga and a new species of Mucor was recorded. An identification key for species of Mucorales from dung in the semi-arid region of Brazil is provided.

  13. Pathways to Resilience in Semi-Arid Economies | IDRC ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    How can populations become resilient to climate change while pursuing economic growth? This question is at the heart of a research project designed to support climate-resilient economic development in semi-arid lands. It will do so by addressing the conditions for economic growth and considering the needs of women ...

  14. Pathways to Resilience in Semi-Arid Economies (PRISE)

    International Development Research Centre (IDRC) Digital Library (Canada)


    should adaptation be integrated into economic development policies? 3. What are the new opportunities for and threats to markets in SALs arising from climate change in semi-arid areas, and how is the private sector adapting? 4. How do natural resource management policies condition vulnerability and resilience in.

  15. Aboveground biomass production of a semi-arid southern African ...

    African Journals Online (AJOL)

    Following a field campaign to determine the species composition, canopy cover, aboveground annual production and leaf area index (LAI) of the semi-arid savanna of north-western Namibia, we present a production model that can be used by graziers to determine the livestock carrying capacity. The model predicts the ...

  16. Mixed livestock grazing in diverse temperate and semi-arid ...

    African Journals Online (AJOL)

    Concerns for product quality, uniformity and continuity and for animal welfare will increasingly drive production processes. In this paper, the potential of mixed grazing for higher output of quality animal products, within these constraints, is assessed under both temperate and semi-arid conditions. Complementary ...

  17. Paclobutrazol biodegradation in unsaturated soil in the Semi-Arid ...

    African Journals Online (AJOL)

    Paclobutrazol (PBZ) is a plant growth regulator, increasing flowe ring and yield that is widely used in mango cultivation in the semi-arid northeastern Brazil. PBZ remains active in the soil for several years. However, it can severely affect the growth and development of subsequent crops, mainly by reducing vegetative vigor.

  18. Soil Compressibility under Irrigated Perennial and Annual Crops in a Semi-Arid Environment

    Directory of Open Access Journals (Sweden)

    Rafaela Watanabe

    Full Text Available ABSTRACT In irrigated soils, a continuous state of high moisture reduces resistance of the soil to applied external forces, favouring compaction. The aim of this study was to evaluate the susceptibility to compaction of developed calcareous soils in irrigated annual and perennial cropping systems of the Apodi Plateau, located in the Brazilian semi-arid region. Four areas of irrigated crops were evaluated: banana after two (B2 and 15 (B15 years cultivation, pasture (P, and a corn and beans succession (MB, as well as the reference areas for soil quality and corresponding natural vegetation (NVB2, NVB15, NVP and NVMB. Samples were collected at layers of 0.00-0.10 and 0.20-0.30 m; and for B2 and B15, samples were collected in the row and inter-row spaces. The following properties were determined: degree of compactness (DC, preconsolidation pressure (σp, compression index (Cc, maximum density (ρmax, critical water content (WCcrit, total organic carbon (TOC and carbon of light organic matter (Clom. Mean values were compared by the t-test at 5, 10, 15 and 20 % probability. An increase was seen in DC at a layer of 0.20-0.30 m in MB (p<0.15, showing the deleterious effects of preparing the soil by ploughing and chiselling, together with the cumulative traffic of heavy machinery. The TOC had a greater influence on ρmax than the stocks of Clom. Irrigation caused a reduction in Cc, and there was no effect on σp at field capacity. The planting rows showed different behaviour for Cc, ρmax, and WCcrit,, and in general the physical properties displayed better conditions than the inter-row spaces. Values for σp and Cc showed that agricultural soils display greater load-bearing capacity and are less susceptible to compaction in relation to soils under natural vegetation.

  19. Tailoring conservation agriculture technologies to West Africa semi-arid zones: Building on traditional local practices for soil restoration

    NARCIS (Netherlands)

    Lahmar, R.; Bationo, B.A.; Lamso, N.D.; Guéro, Y.; Tittonell, P.A.


    Low inherent fertility of tropical soils and degradation, nutrient deficiency and water stress are the key factors that hamper rainfed agriculture in semi-arid West Africa. Conservation Agriculture (CA) is currently promoted in the region as a technology to reduce soil degradation, mitigate the

  20. Biophysical controls on canopy transpiration in a black locust ( Robinia pseudoacacia ) plantation on the semi-arid Loess Plateau, China (United States)

    Lei Jiao; Nan Lu; Ge Sun; Eric J. Ward; Bojie Fu


    In the semi-arid Loess Plateau of China, black locust (Robinia pseudoacacia) was widely planted for soil conservation and afforestation purposes during the past three decades. Investigating biophysical controls on canopy transpiration (Ec) of the plantations is essential to understanding the effects of afforestation on watershed hydrology and regional water resources....

  1. Patch scale turbulence over dryland and irrigated surfaces in a semi-arid landscape during BEAREX08 (United States)

    Quantifying turbulent fluxes of heat and water vapor over heterogeneous surfaces presents unique challenges. For example, in many arid and semi-arid regions, parcels of irrigated cropland are juxtaposed with hot, dry surfaces. Contrasting surface conditions can result in the advection of warm dry ai...

  2. Permafrost distribution modelling in the semi-arid Chilean Andes (United States)

    Azócar, Guillermo F.; Brenning, Alexander; Bodin, Xavier


    Mountain permafrost and rock glaciers in the dry Andes are of growing interest due to the increase in mining industry and infrastructure development in this remote area. Empirical models of mountain permafrost distribution based on rock glacier activity status and temperature data have been established as a tool for regional-scale assessments of its distribution; this kind of model approach has never been applied for a large portion of the Andes. In the present study, this methodology is applied to map permafrost favourability throughout the semi-arid Andes of central Chile (29-32° S), excluding areas of exposed bedrock. After spatially modelling of the mean annual air temperature distribution from scarce temperature records (116 station years) using a linear mixed-effects model, a generalized additive model was built to model the activity status of 3524 rock glaciers. A permafrost favourability index (PFI) was obtained by adjusting model predictions for conceptual differences between permafrost and rock glacier distribution. The results indicate that the model has an acceptable performance (median AUROC: 0.76). Conditions highly favourable to permafrost presence (PFI ≥ 0.75) are predicted for 1051 km2 of mountain terrain, or 2.7 % of the total area of the watersheds studied. Favourable conditions are expected to occur in 2636 km2, or 6.8 % of the area. Substantial portions of the Elqui and Huasco watersheds are considered to be favourable for permafrost presence (11.8 % each), while in the Limarí and Choapa watersheds permafrost is expected to be mostly limited to specific sub-watersheds. In the future, local ground-truth observations will be required to confirm permafrost presence in favourable areas and to monitor permafrost evolution under the influence of climate change.

  3. Situação nutricional e alimentar de pré-escolares no semi-árido da Bahia (Brasil: I.Avaliação antropométrica Nutritional status of pre-school children of the semi-arid region of Bahia (Brazil: I. Anthropometric status

    Directory of Open Access Journals (Sweden)

    Leonor M.P. Santos


    Full Text Available Foram estudados 754 pré-escolares de áreas urbanas de sete municípios do semi-árido da Bahia, Brasil. Os objetivos foram determinar a prevalência de déficit ponderal e estatural, indicativos de desnutrição atual e/ou pregressa e sua associação com a idade, sexo, renda em salário-mínimo (SM, escolaridade materna e adequação do consumo alimentar. Encontrou-se 22,9% de crianças com altura/idade abaixo de -2,0 DP (desnutrição pregressa, 19,1% com peso/idade e 3,6% com peso/altura abaixo de -2,0 DP (desnutrição atual. Em relação ao inquérito dietético somente 6,8% das crianças haviam consumido no dia anterior uma dieta que suprisse os requerimentos energéticos para sua faixa etária. Houve forte associação entre os indicadores A/l e P/l inadequados com renda familiar per capita (p=0,001 e p=0,000, respectivamente; crianças de famílias com renda per capita 1/2 SM. Em relação ao P/A como também P/l, os pré-escolares estudados no semi-árido apresentaram prevalências significativamente superiores às encontradas por pesquisa nacional realizada na mesma época (p=0,047 e p=0,000, respectivamente. Esses achados surpreendem, já que nas últimas décadas tem sido demonstrada no Brasil uma melhoria signifivativa na desnutrição e mortalidade infantil e parecem indicar que as crianças do semi-árido não lograram ainda alcançar os mesmos benefícios que o restante da população infantil brasileira.A survey of 754 preschool children was undertaken in the urban areas of seven small towns of the semi-arid region of Bahia, Northeast Brazil. The study set out to determine the prevalence of weight and height deficits, as well as to correlate them with variables such as age, family income, mother's schooling and food consumption. A prevalence of 22.9% of Height for Age (HA below -2.0 SD was found (stunting and prevalence of 19.1% and 3.6% were determined, respectively for Weight for Age (WA and Weight for Height (WH below -2

  4. Multi-Elements in Source Water (Drinking and Surface Water) within Five Cities from the Semi-Arid and Arid Region, NW China: Occurrence, Spatial Distribution and Risk Assessment. (United States)

    Wu, Ting; Li, Xiaoping; Yang, Tao; Sun, Xuemeng; Mielke, Howard W; Cai, Yue; Ai, Yuwei; Zhao, Yanan; Liu, Dongying; Zhang, Xu; Li, Xiaoyun; Wang, Lijun; Yu, Hongtao


    The purpose of this study was to identify the concentration of multi-elements (MEs) in source water (surface and drinking water) and assess their quality for sustainability. A total of 161 water samples including 88 tap drinking waters (DW) and 73 surface waters (SW) were collected from five cities in Xi'an, Yan'an, Xining, Lanzhou, and Urumqi in northwestern China. Eighteen parameters including pH, electrical conductivity (EC), total organic carbon (TOC) total nitrogen (TN), chemical compositions of anions (F - , Cl - , NO₃ - ,HCO₃ - , SO₄ 2- ), cations (NH₄⁺, K⁺, Na⁺, Ca 2+ ,Mg 2+ ), and metals (lead (Pb), chromium (Cr), cadmium (Cd), copper (Cu)) were analyzed in the first time at the five cities . The results showed that pH values and concentrations of Cl - , SO₄ 2- , Na⁺, K⁺, Ca 2+ , Mg 2+ and Cd, Cr, Cu in DW were within the permissible limits of the Chinese Drinking Water Quality Criteria, whereas the concentrations of other ions (F - , NO₃ - , NH₄⁺ and Pb) exceeded their permissible values. In terms of the SW, the concentrations of F - , Cl - , NO₃ - , SO₄ 2- were over the third range threshold i.e., water suitable for fishing and swimming of the Surface Water Quality Standards in China. The spatial distributions of most MEs in source water are similar, and there was no clear variation for all ions and metals. The metals in DW may be caused by water pipes, faucets and their fittings. The noncarcinogenic risk of metals in DW for local children are in decreasing order Cr > Cd > Pb > Cu. The carcinogenic risk from Cr exposure was at the acceptable level according to threshold of USEPA. Although the comprehensive index of potential ecological assessment of Cr, Cd, Pb and Cu in SW ranked at low risk level and was in the order of Huang River in Xining > Peaceful Canal in Urumqi > Yan River in Yan'an > Yellow River in Lanzhou, their adverse effects to ecology and human health at a low concentration in local semi-arid and arid areas

  5. Multi-Elements in Source Water (Drinking and Surface Water within Five Cities from the Semi-Arid and Arid Region, NW China: Occurrence, Spatial Distribution and Risk Assessment

    Directory of Open Access Journals (Sweden)

    Ting Wu


    Full Text Available The purpose of this study was to identify the concentration of multi-elements (MEs in source water (surface and drinking water and assess their quality for sustainability. A total of 161 water samples including 88 tap drinking waters (DW and 73 surface waters (SW were collected from five cities in Xi’an, Yan’an, Xining, Lanzhou, and Urumqi in northwestern China. Eighteen parameters including pH, electrical conductivity (EC, total organic carbon (TOC total nitrogen (TN, chemical compositions of anions (F−, Cl−, NO3−,HCO3−, SO42−, cations (NH4+, K+, Na+, Ca2+,Mg2+, and metals (lead (Pb, chromium (Cr, cadmium (Cd, copper (Cu were analyzed in the first time at the five cities . The results showed that pH values and concentrations of Cl−, SO42−, Na+, K+, Ca2+, Mg2+ and Cd, Cr, Cu in DW were within the permissible limits of the Chinese Drinking Water Quality Criteria, whereas the concentrations of other ions (F−, NO3−, NH4+ and Pb exceeded their permissible values. In terms of the SW, the concentrations of F−, Cl−, NO3−, SO42− were over the third range threshold i.e., water suitable for fishing and swimming of the Surface Water Quality Standards in China. The spatial distributions of most MEs in source water are similar, and there was no clear variation for all ions and metals. The metals in DW may be caused by water pipes, faucets and their fittings. The noncarcinogenic risk of metals in DW for local children are in decreasing order Cr > Cd > Pb > Cu. The carcinogenic risk from Cr exposure was at the acceptable level according to threshold of USEPA. Although the comprehensive index of potential ecological assessment of Cr, Cd, Pb and Cu in SW ranked at low risk level and was in the order of Huang River in Xining > Peaceful Canal in Urumqi > Yan River in Yan’an > Yellow River in Lanzhou, their adverse effects to ecology and human health at a low concentration in local semi-arid and arid areas should not be ignored in

  6. An Overview of Biodegradation of LNAPLs in Coastal (Semi)-arid Environment.

    KAUST Repository

    Yadav, Brijesh Kumar


    Contamination of soil and water due to the release of light non-aqueous phase liquids (LNAPLs) is a ubiquitous problem. The problem is more severe in arid and semi-arid coastal regions where most of the petroleum production and related refinery industries are located. Biological treatment of these organic contaminated resources is receiving increasing interests and where applicable, can serve as a cost-effective remediation alternative. The success of bioremediation greatly depends on the prevailing environmental variables, and their remediation favoring customization requires a sound understanding of their integrated behavior on fate and transport of LNAPLs under site-specific conditions. The arid and semi-arid coastal sites are characterized by specific environmental extremes; primarily, varying low and high temperatures, high salinity, water table dynamics, and fluctuating soil moisture content. An understanding of the behavior of these environmental variables on biological interactions with LNAPLs would be helpful in customizing the bioremediation for restoring problematic sites in these regions. Therefore, this paper reviews the microbial degradation of LNAPLs in soil-water, considering the influences of prevailing environmental parameters of arid and semi-arid coastal regions. First, the mechanism of biodegradation of LNAPLs is discussed briefly, followed by a summary of popular kinetic models used by researchers for describing the degradation rate of these hydrocarbons. Next, the impact of soil moisture content, water table dynamics, and soil-water temperature on the fate and transport of LNAPLs are discussed, including an overview of the studies conducted so far. Finally, based on the reviewed information, a general conclusion is presented with recommendations for future research subjects on optimizing the bioremediation technique in the field under the aforesaid environmental conditions. The present review will be useful to better understand the

  7. Prevalence and factors associated with stunting and excess weight in children aged 0-5 years from the Brazilian semi-arid region. (United States)

    Ramos, Clariana V; Dumith, Samuel C; César, Juraci A


    To analyze the prevalence of excess weight and low height, and identify associated factors among children younger than five years. Cross-census study. A total of 1,640 children from two municipalities in Piauí, Brazil were included. The prevalence of low height was 10.9% (95% CI: 9.3 to 12.4), inversely associated with mother's younger age and low level of education, lower socioeconomic status, mothers who had fewer than six prenatal consultations, and households that had more than one child younger than 5 years. Excess weight prevalence was 19.1% (95% CI: 17.2 to 21.0), and remained inversely associated with lower maternal age, low maternal education, and cesarean delivery. Stunting was greater in children aged between 12 and 23 months, while excess weight decreased with age. It is noteworthy that the stunting rate, although decreasing, is still high, while the prevalence of excess weight, even in this very poor area, already exceeds the expected percentage for a population with better socioeconomic level. Copyright © 2014 Sociedade Brasileira de Pediatria. Published by Elsevier Editora Ltda. All rights reserved.

  8. Effects of irrigation and plastic mulch on soil properties on semi-arid abandoned fields


    Van der Meulen, E.S.; Nol, L.; Cammeraat, L.H.


    The Guadalentín Basin in Spain is one of the driest areas of Europe and has problems with high evaporation rates, and high risks of desertification exist including soil quality loss and soil erosion. Farmers in this semi-arid region use polyethylene covers on their irrigated croplands to reduce evaporation in order to enhance crop yield. When farmers abandon the acres, they leave the plastic covers on the fields. Up to now research has been concentrating on the effects of plastic covers on cr...

  9. Role of radiatively forced temperature changes in enhanced semi-arid warming over East Asia (United States)

    Guan, X.; Huang, J.; Guo, R.; Lin, P.; Zhang, Y.


    As the climate change occurred over East Asia since 1950s, intense interest and debate have arisen concerning the contribution of human activities to the warming observed in previous decades. In this study, we investigate surface temperature change using a recently developed methodology that can successfully identify and separate the dynamically induced temperature (DIT) and radiatively forced temperature (RFT) changes in raw surface air temperature (SAT) data. For regional averages, DIT and RFT make 43.7 and 56.3 % contributions to the SAT over East Asia, respectively. The DIT changes dominate the SAT decadal variability and are mainly determined by internal climate variability, such as the North Atlantic Oscillation (NAO), Pacific Decadal Oscillation (PDO), and Atlantic Multi-decadal Oscillation (AMO). The radiatively forced SAT changes made major contribution to the global-scale warming trend and the regional-scale enhanced semi-arid warming (ESAW). Such enhanced warming is also found in radiatively forced daily maximum and minimum SAT. The long-term global-mean SAT warming trend is mainly related to radiative forcing produced by global well-mixed greenhouse gases. The regional anthropogenic radiative forcing, however, caused the enhanced warming in the semi-arid region, which may be closely associated with local human activities. Finally, the relationship between global warming hiatus and regional enhanced warming is discussed.

  10. Land cover controls on summer discharge and runoff solution chemistry of semi-arid urban catchments (United States)

    Gallo, Erika L.; Brooks, Paul D.; Lohse, Kathleen A.; McLain, Jean E. T.


    SummaryRecharge of urban runoff to groundwater as a stormwater management practice has gained importance in semi-arid regions where water resources are scarce and urban centers are growing. Despite this trend, the importance of land cover in controlling semi-arid catchment runoff quantity and quality remains unclear. Here we address the question: How do land cover characteristics control the amount and quality of storm runoff in semi-arid urban catchments? We monitored summertime runoff quantity and quality from five catchments dominated by distinct urban land uses: low, medium, and high density residential, mixed use, and commercial. Increasing urban land cover increased runoff duration and the likelihood that a rainfall event would result in runoff, but did not increase the time to peak discharge of episodic runoff. The effect of urban land cover on hydrologic responses was tightly coupled to the magnitude of rainfall. At distinct rainfall thresholds, roads, percent impervious cover and the stormwater drainage network controlled runoff frequency, runoff depth and runoff ratios. Contrary to initial expectations, runoff quality did not vary in repose to impervious cover or land use. We identified four major mechanisms controlling runoff quality: (1) variable solute sourcing due to land use heterogeneity and above ground catchment connectivity; (2) the spatial extent of pervious and biogeochemically active areas; (3) the efficiency of overland flow and runoff mobilization; and (4) solute flushing and dilution. Our study highlights the importance of the stormwater drainage systems characteristics in controlling urban runoff quantity and quality; and suggests that enhanced wetting and in-stream processes may control solute sourcing and retention. Finally, we suggest that the characteristics of the stormwater drainage system should be integrated into stormwater management approaches.

  11. Carbon cycle responses of semi-arid ecosystems to positive asymmetry in rainfall. (United States)

    Haverd, Vanessa; Ahlström, Anders; Smith, Benjamin; Canadell, Josep G


    Recent evidence shows that warm semi-arid ecosystems are playing a disproportionate role in the interannual variability and greening trend of the global carbon cycle given their mean lower productivity when compared with other biomes (Ahlström et al. 2015 Science, 348, 895). Using multiple observations (land-atmosphere fluxes, biomass, streamflow and remotely sensed vegetation cover) and two state-of-the-art biospheric models, we show that climate variability and extremes lead to positive or negative responses in the biosphere, depending on vegetation type. We find Australia to be a global hot spot for variability, with semi-arid ecosystems in that country exhibiting increased carbon uptake due to both asymmetry in the interannual distribution of rainfall (extrinsic forcing), and asymmetry in the response of gross primary production (GPP) to rainfall change (intrinsic response). The latter is attributable to the pulse-response behaviour of the drought-adapted biota of these systems, a response that is estimated to be as much as half of that from the CO 2 fertilization effect during 1990-2013. Mesic ecosystems, lacking drought-adapted species, did not show an intrinsic asymmetric response. Our findings suggest that a future more variable climate will induce large but contrasting ecosystem responses, differing among biomes globally, independent of changes in mean precipitation alone. The most significant changes are occurring in the extensive arid and semi-arid regions, and we suggest that the reported increased carbon uptake in response to asymmetric responses might be contributing to the observed greening trends there. © 2016 John Wiley & Sons Ltd.

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

    Directory of Open Access Journals (Sweden)

    Lin Deng


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

  13. Estimation of crop water requirement for onion in Maiduguri, a semi-arid environment

    Directory of Open Access Journals (Sweden)

    M. Yaji


    Full Text Available The estimation of peak crop water requirement for matching farm sizes with available water is necessary for efficient water management. There are various methods of predicting crop water requirements ranging from those requiring several measured weather data (Penman, Jensen & Haise, and by Radiation; to those requiring single measured weather data (Blaney-Criddle and the direct evaporation from class “A” pan. Out of these methods the most suitable method for estimating the crop water requirements for onion in Maiduguri a semi arid environment was determined to be the modified Blaney-Criddle method. The method was used to estimate the peak irrigation requirement for onion and was found to be in April amounting to 67 m3/day/ha which is equivalent to 1.28 l/s/ha at 60% efficiency. This value is within the acceptable limits of 1.0-1.5 l/s/ha recommended for canal design in arid and semi-arid regions.

  14. Performance of fenugreek bioinoculated with Rhizobium meliloti strains under semi-arid condition. (United States)

    Singh, N K; Patel, D B


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

  15. Richness and distribution of aquatic macrophytes in Brazilian semi-arid aquatic ecosystems Riqueza e distribuição de macrófitas aquáticas em ecossistemas aquáticos do semi-árido brasileiro

    Directory of Open Access Journals (Sweden)

    Gustavo Gonzaga Henry-Silva


    Full Text Available AIM: The aim of this study was to evaluate the richness and distribution of the aquatic macrophytes in the basin of the Apodi/Mossoró River, in the semi-arid region (caatinga of Rio Grande do Norte, Brazil; METHODS: A survey of the floristic composition of the aquatic macrophytes was made at 20 sampling stations in the basin at four seasons (August/2007, November/2007, February/2008, May/2008. Specimens of each species were collected and deposited in the Dárdano de Andrade Lima Herbarium of the Universidade Federal Rural do Semi-Árido; RESULTS: We found 40 species of aquatic macrophytes, in 33 genera and 22 families. The families with the most species were Poaceae and Cyperaceae, and the most species-rich genera were Cyperus and Eleocharis. The most common plant form was amphibian (42.5%, followed by emergent (27.5%, free-floating (12.5%, rooted-submersed (10.0%, and floating-leaved (7.5%. The lowest richness was observed at the estuarine region (3 species, and the highest richness in the upper basin (17 species. The rooted-submersed Hydrothrix gardneri Hooker f. and Ceratophyllum demersum L. were observed in great abundance and frequency in the Santa Cruz Reservoir of Apodi, especially in areas close to cage farms of Nile tilapia (Oreochromis niloticus (Linnaeus, 1758. The most common free-floating species were Eichhornia crassipes (Mart. Solms., Pistia stratiotes L., and Salvinia auriculata Aubl., predominantly in stretches that run through urban centers; CONCLUSION: The species richness of aquatic macrophytes in aquatic environments of the caatinga is similar to that observed in other basins of Brazil. Because of the many dams and reservoirs in the semi-arid Northeast, inventory and monitoring of aquatic macrophytes have become essential, especially in basins that will receive water from the diversion of the São Francisco River.OBJETIVO: Nós objetivamos avaliar a riqueza e a distribuição das macrófitas aquáticas nos ambientes aqu

  16. Economic valuation of sheep genetic resources: implications for sustainable utilization in the Kenyan semi-arid tropics. (United States)

    Omondi, I; Baltenweck, I; Drucker, A G; Obare, G; Zander, K K


    Sheep, recognised as one of the important livestock species especially in the semi-arid tropics with high genetic resource potentials, can be exploited through sustainable utilization in order to improve livestock keepers' livelihoods. This study presents the evaluation of the economic values of sheep genetic resources (SGR) in terms of the important non-market traits embedded in sheep and how this information can be utilised to improve livelihoods in semi-arid regions. The results obtained from mixed logit models results derived from stated choice data collected from 157 respondents in the semi-arid Marsabit district of Kenya reveal that disease resistance is the most highly valued trait whose resultant increment results into a welfare improvement of up to KShs.1537. Drought tolerance and fat deposition traits were found to be implicitly valued at KShs.694 and 738 respectively. The results further point out that for livestock stakeholders to effectively improve the livelihoods of poor livestock-keepers, development strategies for improving the management and/or utilisation of SGR in terms of drought tolerance, should not only be tailor made to target regions that are frequently devastated by drought but should also succeed other strategies or efforts that would first lead to the improvement of producers' economic status.

  17. Hydrologic feasibility of artificial forestation in the semi-arid Loess Plateau of China

    Directory of Open Access Journals (Sweden)

    T. T. Jin


    Full Text Available Hydrologic viability, in terms of moisture availability, is fundamental to ecosystem sustainability in arid and semi-arid regions. In this study, we examine the spatial distribution and after-planting variations of soil moisture content (SMC in black locust tree (Robinia pseudoacacia L. plantings in the Loess Plateau of China at a regional scale. Thirty sites (5 to 45 yr old were selected, spanning an area of 300 km by 190 km in the northern region of the Shaanxi Province. The SMC was measured to a depth of 100 cm at intervals of 10 cm. Geographical, topographic and vegetation information was recorded, and soil organic matter was evaluated. The results show that, at the regional scale, SMC spatial variability was most highly correlated with rainfall. The negative relationship between the SMC at a depth of 20–50 cm and the stand age was stronger than at other depths, although this relationship was not significant at a 5 % level. Watershed analysis shows that the after-planting SMC variation differed depending upon precipitation. The SMC of plantings in areas receiving sufficient precipitation (e.g., mean annual precipitation (MAP of 617 mm may increase with stand age due to improvements in soil water-holding capacity and water-retention abilities after planting. For areas experiencing water shortages (e.g., MAP = 509 mm, evapotranspiration may cause planting soils to dry within the first 20 yr of growth. It is expected that, as arid and semi-arid plantings age, evapotranspiration will decrease, and the soil profile may gradually recover. In extremely dry areas (e.g., MAP = 352 mm, the variation in after-planting SMC with stand age was found to be negligible. The MAP can be used as an index to divide the study area into different ecological regions. Afforestation may sequentially exert positive, negative and negligible effects on SMCs with a decrease in the MAP. Therefore, future restoration measures should correspond to the local climate

  18. Nitrogen cycling: water use efficiency interactions in semi-arid ecosystems in relation to management of tree legumes (Prosopis)

    Energy Technology Data Exchange (ETDEWEB)

    Felker, P.; Clark, P.R.; Osborn, J.; Cannell, G.H.


    Plant productivity in semi-arid ecosystems is often limited by soil fertility as much as it is by moisture availability. A quantitative assessment of nitrogen limitations on water use efficiency has been made after careful review of plant water use efficiency data at high and low soil fertilities and after careful review of nitrogen inputs to semi arid ecosystems in the form of: blue-green algae-lichen crusts; non-symbiotic nitrogen fixers; rainfall; and tree legumes. This analysis indicates that plant productivity in semi-arid regions may be 10 fold more limited by nitrogen than moisture availability. Forage yields of non-nitrogen fixing trees and shrubs could be greatly increased by interplanting with drought adapted nitrogen fixers such as Prosopis and Acacia. Calculations based on water use efficiencies of annual legumes and nitrogen fixation values of tree legumes predict that well managed, spaced, and cared for orchards of specially selected Prosopis could produce 4000 Kgha/sup -1/ yr/sup -1/ of 13% protein pods at 500 mm annual rainfall with only light fertilization with phosphate, potassium and sulfur. Field measurements of pod yields for 25 selections of 3 year old Prosopis grown under managed orchard conditions in southern California are presented. Spacing regimes and harvesting techniques for Prosopis are proposed to facilitate pod production.

  19. Effects of legume cover crop and sub-soiling on soil properties and Maize (Zea mays L) growth in semi arid area of Machakos district, Kenya = Efecto del cultivo de cobertua y el subsolado sobre las propiedades del suelo y crecimiento de maiz (Zea mays L.) en la region semi arida de Machakos, Kenia

    NARCIS (Netherlands)

    Karuma, A.; Gachene, C.K.K.; Gicheru, P.; Mwangombe, A.W.; Mwangi, H.W.; Clavel, D.; Verhagen, A.; Kaufmann, Von R.; Francis, J.; Ekaya, W.


    Low crop yields in the semi arid areas of Kenya have been attributed to, among other factors, low soil fertility, low farm inputs, labour constraints and inappropriate tillage practices that lead to pulverized soils. The aim of this study was to determine the effects of legume cover crops (LCC) on

  20. Understanding runoff processes in a semi-arid environment through isotope and hydrochemical hydrograph separations (United States)

    Camacho Suarez, V. V.; Saraiva Okello, A. M. L.; Wenninger, J. W.; Uhlenbrook, S.


    The understanding of runoff generation mechanisms is crucial for the sustainable management of river basins such as the allocation of water resources or the prediction of floods and droughts. However, identifying the mechanisms of runoff generation has been a challenging task, even more so in arid and semi-arid areas where high rainfall and streamflow variability, high evaporation rates, and deep groundwater reservoirs may increase the complexity of hydrological process dynamics. Isotope and hydrochemical tracers have proven to be useful in identifying runoff components and their characteristics. Moreover, although widely used in humid temperate regions, isotope hydrograph separations have not been studied in detail in arid and semi-arid areas. Thus the purpose of this study is to determine whether isotope hydrograph separations are suitable for the quantification and characterization of runoff components in a semi-arid catchment considering the hydrological complexities of these regions. Through a hydrochemical characterization of the surface water and groundwater sources of the catchment and two- and three-component hydrograph separations, runoff components of the Kaap catchment in South Africa were quantified using both isotope and hydrochemical tracers. No major disadvantages while using isotope tracers over hydrochemical tracers were found. Hydrograph separation results showed that runoff in the Kaap catchment is mainly generated by groundwater sources. Two-component hydrograph separations revealed groundwater contributions of between 64 and 98 % of total runoff. By means of three-component hydrograph separations, runoff components were further separated into direct runoff, shallow and deep groundwater components. Direct runoff, defined as the direct precipitation on the stream channel and overland flow, contributed up to 41 % of total runoff during wet catchment conditions. Shallow groundwater defined as the soil water and near-surface water component (and

  1. The use of soil quality indicators to assess soil functionality in restored semi-arid ecosystems (United States)

    Muñoz-Rojas, Miriam; Erickson, Todd E.; Dixon, Kingsley W.; Merritt, David J.


    Keywords: Pilbara, 1-day CO2 test, microbial activity, mine restoration, soil health, ecosystem services. Introduction Semi-arid and arid environments are highly vulnerable to land degradation and their restoration has commonly showed low rates of success (James et al., 2013). A systematic knowledge of soil functionality is critical to successful restoration of degraded ecosystems since approximately 80% of ecosystem services can be connected to soil functions. The assessment of soil functionality generally involves the evaluation of soil properties and processes as they relate to the ability of soil to function effectively as a component of a healthy ecosystem (Costantini et al., 2015) Using soil quality indicators may be a valuable approach to assess functionality of topsoil and novel substrates used in restoration (Muñoz-Rojas et al., 2014; 2015). A key soil chemical indicator is soil organic C, that has been widely used as an attribute of soil quality because of the many functions that it provides and supports (Willaarts et al., 2015). However, microbial indicators can be more sensitive to disturbances and could be a valuable addition in soil assessment studies in restoration programs. Here, we propose a set of soil quality indicators to assess the soil status in restored soils (topsoil and waste material) of semi-arid environments. The study was conducted during March 2015 in the Pilbara biogeographical region (northwestern Australia) at an iron ore mine site rehabilitated in 2011. Methods Soil samples were collected from two sub-areas with different soil materials used as growth media: topsoil retrieved from nearby stockpiles and a lateritic waste material utilised for its erosive stability and physical competence. An undisturbed natural shrub-grassland ecosystem dominated by Triodia spp. and Acacia spp. representative of the restored area was selected as the analogue reference site. Soil physicochemical analysis were undertaken according to standard methods

  2. Is the future blue-green or brown? The effects of extreme events on phytoplankton dynamics in a semi-arid man-made lake

    NARCIS (Netherlands)

    Meideiros, L.D.C.; Mattos, A.; Lurling, M.F.L.L.W.; Becker, V.


    In arid and semi-arid regions, a hydrological regime characterized by an annual cycle of drought and rainy seasons changes the volume and retention time of reservoirs. Such changes affect the limnological characteristics and lead to changes on phytoplankton community. Phytoplankton seasonal

  3. The dominant role of semi-arid ecosystems in the trend and variability of the land CO2 sink

    DEFF Research Database (Denmark)

    Ahlström, Anders; Raupach, Michael R.; Schurgers, Guy


    regions. Whereas the mean sink is dominated by highly productive lands (mainly tropical forests), the trend and interannual variability of the sink are dominated by semi-arid ecosystems whose carbon balance is strongly associated with circulation-driven variations in both precipitation and temperature....

  4. Surficial weathering of iron sulfide mine tailings under semi-arid climate. (United States)

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


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

  5. Comportamento de seis variedades de pomelo (Citrus paradisi Macfad. cultivadas sob irrigação na região semi-árida de Pernambuco Behavior of six grapefruit varieties grown under irrigation at the semi-arid region of Pernambuco - Brazil

    Directory of Open Access Journals (Sweden)

    Ildo Eliezer Lederman


    Full Text Available O uso da irrigação nas regiões semi-áridas do Nordeste brasileiro tem viabilizado o cultivo comercial de inúmeras fruteiras, tais como a uva, a manga, a goiaba, o coco e a banana. Outras espécies, como o pomelo, ou grapefruit, vêm sendo ainda objeto de estudos e avaliações. Uma coleção formada de 06 variedades de pomelos (Citrus paradisi, de polpas com coloração rosa-avermelhada ('Marsh Foster', 'Star Ruby', 'Rio Red' e 'Red Blush' e amarelada ('Triumph' e 'Marsh Foster Nucelar', foi implantada em 1993 na Estação Experimental de Ibimirim, localizada no município de Ibimirim, no Vale do Rio Moxotó - região semi-árida de Pernambuco. Contando com cinco plantas por parcela, a coleção foi conduzida sob irrigação localizada e as avaliações realizadas durante três anos (2000 a 2002. Os resultados demostraram alta variabilidade na produção de frutos, tendo a variedade 'Marsh Foster Nucelar' alcançado a produção média de 135,0 kg/planta, enquanto a 'Star Ruby' atingiu apenas 31,0 kg/planta. O peso médio dos frutos variou de 285,5g ('Red Blush' até um máximo de 401,6g na variedade 'Triumph'. O volume de suco extraído, os sólidos solúveis totais (SST, a acidez total titulável (ATT e a relação SSS/ATT também apresentaram mudanças entre as variedades estudadas.The use of irrigation at the semi-arid region of Northeast Brazil has made feasible several commercial fruit trees crops such as grapevines, mango, guava, coconut, banana and others, like grapefruit, which actually is being studied. A collection formed by six grapefruit varieties showing a pink-red pulp color (Marsh Foster, Star Ruby, Rio Red and Red Blush and a creamy color (Triumph and Marsh Foster Nucelar and consisting of five plants/plot was installed in 1993 at the Ibimirim Experimental Station, located in the Moxotó river valley at the semi-arid region of Pernambuco - Northeast Brazil, under irrigation. Evaluations carried out during three years (from

  6. Prevalência e determinantes de obesidade e sobrepeso em mulheres em idade reprodutiva residentes na região semiárida do Brasil Prevalence and determinants of obesity and overweight among reproductive age women living in the semi-arid region of Brazil

    Directory of Open Access Journals (Sweden)

    Luciano Lima Correia


    Full Text Available O estudo estimou a prevalência e identificou fatores determinantes do sobrepeso e obesidade em mulheres em idade fértil na região semiárida do Brasil. Na amostra por conglomerados de oito mil domicílios do estado do Ceará, foram pesquisadas 6.845 mulheres. Sobrepeso e obesidade foram medidos pelo Índice de Massa Corporal, utilizando-se a análise multivariada para a identificação dos fatores determinantes. As prevalências de sobrepeso e obesidade foram de 32,6% e 16,1%, respectivamente. Na análise ajustada, a obesidade esteve positivamente associada a: idade >30 anos (RP=1,55, estado civil casada (RP=1,36, escolaridade fundamental (RP=1,40, idade na menarca 1 filho (RP=1,65, uso de contraceptivos (RP=1,31. Os fatores relacionados à saúde e à nutrição, referentes à obesidade mórbida, foram: hipertensão arterial (RP=3,11, diabetes (RP=2,08, insatisfação com a imagem corporal (RP=4,26 e procedimentos para perder peso (RP=2,73. Sobrepeso e obesidade são altamente prevalentes na região semiárida. A educação foi o único fator socioeconômico passível de ser modificado. Os fatores reprodutivos identificados apontam para a necessidade de mobilização dos serviços de pré-natal, pós-parto e planejamento familiar na prevenção e no controle da obesidade.The study estimated the prevalence and determinants of overweight and obesity in women of reproductive age in the Semi-Arid Region of Brazil. In the cluster sampling of 8,000 households of the state of Ceará, 6,845 women were surveyed. Overweight and obesity were measured by the body mass index and risk factors identified by multivariate analysis. The prevalences of overweight and obesity were 32.6% and 16.1%, respectively. After adjusted analysis, obesity was positively associated with age >30 years (PR = 1.55, marital status, married (PR = 1.36, elementary education (PR = 1.40, age at menarche 1 child (PR = 1.65 and contraceptive use (PR = 1.31. Specific health and

  7. Conidial fungi from the semi-arid Caatinga biome of Brazil: The genus Menisporopsis

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    Alisson Cardoso Rodrigues da Cruz


    Full Text Available The genus Menisporopsis S. Hughes is characterized by synnematous conidiomata around a central seta, phialidic conidiogenous cells and falcate to lunate 0- to 1-septate conidia with terminal setulae. Currently, nine species are included in the genus. In the course of investigating conidial fungi associated with decaying plant material in the semi-arid region of Brazil, we identified five Menisporopsis species: M. kobensis Matsush.; M. novae-zelandiae S. Hughes & Kendr.; M. pirozynskii Varghese & Rao; M. profusa Piroz. & Hodges; and M. theobromae S. Hughes. Ours represents only the second record of M. kobensis for the world. We present descriptions, comments, geographic distributions and illustrations for all five species, as well as a key to the recognized species.

  8. Coupled flow and salinity transport modelling in semi-arid environments

    DEFF Research Database (Denmark)

    Bauer-Gottwein, Peter; Held, R.J.; Zimmermann, S.


    Numerical groundwater modelling is used as the base for sound aquifer system analysis and water resources assessment. In many cases, particularly in semi-arid and arid regions, groundwater flow is intricately linked to salinity transport. A case in point is the Shashe River Valley in Botswana....... A freshwater aquifer located around an ephemeral stream is depleted by the combined effect of transpiration and pumping. Quantitative system analysis reveals that the amount of water taken by transpiration is far more than the quantities pumped for water supply. Furthermore, the salinity distribution...... in and around Shashe River Valley as well as its temporal dynamics can be satisfactorily reproduced if the transpiration is modelled as a function of groundwater salinity. The location and dynamics of the saltwater–freshwater interface are highly sensitive to the parameterization of evaporative...

  9. Variability of atmospheric carbonyl sulfide at a semi-arid urban site in western India. (United States)

    Mallik, Chinmay; Chandra, Naveen; Venkataramani, S; Lal, Shyam


    Atmospheric carbonyl sulfide (COS) is a major precursor for sulfate aerosols that play a critical role in climate regulation. Recent studies have highlighted the importance of COS measurements as a reliable means to constrain biospheric carbon assimilation. In a scenario of limited availability of COS data around the globe, we present gas-chromatographic measurements of atmospheric COS mixing ratios over Ahmedabad, a semi-arid, urban region in western India. These measurements, being reported for the first time over an Indian site, enable us to understand the diurnal and seasonal variation in atmospheric COS with respect to its natural, anthropogenic and photochemical sources and sinks. The annual mean COS mixing ratio over Ahmedabad is found to be 0.83±0.43ppbv, which is substantially higher than free tropospheric values for the northern hemisphere. Inverse correlation of COS with soil and skin temperature, suggests that the dry soil of the semi-arid study region is a potential sink for atmospheric COS. Positive correlations of COS with NO2 and CO during post-monsoon and the COS/CO slope of 0.78pptv/ppbv reveals influence of diesel combustion and tire wear. The highest concentrations of COS are observed during pre-monsoon; COS/CO2 slope of 44.75pptv/ppmv combined with information from air mass back-trajectories reveal marshy wetlands spanning over 7500km(2) as an important source of COS in Ahmedabad. COS/CO2 slopes decrease drastically (8.28pptv/ppmv) during post-monsoon due to combined impact of biospheric uptake and anthropogenic emissions. Copyright © 2016 Elsevier B.V. All rights reserved.

  10. Spatio-temporal topsoil organic carbon mapping of a semi-arid Mediterranean region: The role of land use, soil texture, topographic indices and the influence of remote sensing data to modelling

    KAUST Repository

    Schillaci, Calogero


    SOC is the most important indicator of soil fertility and monitoring its space-time changes is a prerequisite to establish strategies to reduce soil loss and preserve its quality. Here we modelled the topsoil (0–0.3m) SOC concentration of the cultivated area of Sicily in 1993 and 2008. Sicily is an extremely variable region with a high number of ecosystems, soils, and microclimates. We studied the role of time and land use in the modelling of SOC, and assessed the role of remote sensing (RS) covariates in the boosted regression trees modelling. The models obtained showed a high pseudo-R2 (0.63–0.69) and low uncertainty (s.d.<0.76gCkg−1 with RS, and <1.25gCkg−1 without RS). These outputs allowed depicting a time variation of SOC at 1arcsec. SOC estimation strongly depended on the soil texture, land use, rainfall and topographic indices related to erosion and deposition. RS indices captured one fifth of the total variance explained, slightly changed the ranking of variance explained by the non-RS predictors, and reduced the variability of the model replicates. During the study period, SOC decreased in the areas with relatively high initial SOC, and increased in the area with high temperature and low rainfall, dominated by arables. This was likely due to the compulsory application of some Good Agricultural and Environmental practices. These results confirm that the importance of texture and land use in short-term SOC variation is comparable to climate. The present results call for agronomic and policy intervention at the district level to maintain fertility and yield potential. In addition, the present results suggest that the application of RS covariates enhanced the modelling performance.

  11. Uso e qualidade da água subterrânea para irrigação no semi-árido piauiense Use and quality of groundwater for irrigation in semi-arid region of the Piauí State, Brazil

    Directory of Open Access Journals (Sweden)

    Aderson S. de Andrade Júnior


    Full Text Available A região semi-árida do Estado do Piauí é caracterizada por baixa intensidade pluviométrica e elevadas taxas de evapotranspiração. Porém a reserva de água subterrânea torna possível o desenvolvimento de atividades antrópicas, potencializada, na maioria dos casos, pelas características hidrogeológicas do subsolo, que permitem explotações de alta vazão de água com boa qualidade; todavia, alguns poços atingem formações de baixa vazão e qualidade de água com concentração de sais elevada e que, se utilizada para irrigação, pode ocasionar a salinização e a sodificação dos solos. Dessa forma, objetivou-se caracterizar as formas de uso e a qualidade das águas subterrâneas em parte da região semi-árida do Piauí, visando ao seu uso para irrigação. Coletaram-se amostras em 225 poços distribuídos espacialmente, nas quais foram analisadas as seguintes variáveis: condutividade elétrica, sódio, cálcio, magnésio, relação de adsorção de sódio, carbonato, bicarbonato, cloreto e sulfato. Em relação ao uso da água, predominou o uso doméstico (53,61%, seguido pela irrigação (21,17%, com os seguintes métodos: gotejamento (14,03%; microaspersão (3,83%; aspersão convencional (16,11%; canhão e autopropelido (13,66%; superfície (16,76% e outros métodos artesanais (35,52%. Os mapas de classes de risco de uso para irrigação, gerados a partir da qualidade da água subterrânea, evidenciam a ocorrência de sub-áreas com as seguintes classes: nenhuma restrição, moderada restrição e severa restrição.The semi-arid region in the State of Piauí, Brazil, is characterized by low rain fall and high evapotranspiration. However, the groundwater reserves make possible the economic development by underground hydrogeology characteristics, which allow extractions of high water flow with good quality, in most of the cases. However, some wells reached formations that have low discharge and water with high salt

  12. Mapping of Temporal Surface-water Resources Availability and Agricultural Adaptability due to Climate Change and Anthropogenic Activity in a Hot Semi-arid Region of Maharashtra State, India (United States)

    Roy, A.; Inamdar, A. B.


    Major part of Godavari River Basin is intensely drought prone and climate vulnerable in the Western Maharashtra State, India. The economy of the state depends on the agronomic productivity of this region. So, it is necessary to regulate the effects of existing and upcoming hydro-meteorological advances in various strata. This study investigates and maps the surface water resources availability and vegetation, their decadal deviations with multi-temporal LANDSAT images; and finally quantifies the agricultural adaptations. This work involves the utilization of Remote Sensing and GIS with Hydrological modeling. First, climatic trend analysis is carried out with NCEP dataset. Then, multi-temporal LANDSAT images are classified to determine the decadal LULC changes and correlated to the community level hydrological demand. Finally, NDVI, NDWI and SWAT model analysis are accomplished to determine irrigated and non-irrigated cropping area for identifying the agricultural adaptations. The analysis shows that the mean value of annual and monsoon rainfall is significantly decreasing, whereas the mean value of annual and summer temperature is increasing significantly and the winter temperature is decreasing. The analysis of LANDSAT images shows that the surface water availability is highly dependent on climatic conditions. Barren-lands are most dynamic during the study period followed by, vegetation, and water bodies. The spatial extent of barren-lands is increased drastically during the climate vulnerable years replacing the vegetation and surface water bodies. Hence, the barren lands are constantly increasing and the vegetation cover is linearly decreasing, whereas the water extent is changing either way in a random fashion. There appears a positive correlation between surface water and vegetation occurrence; as they are fluctuating in a similar fashion in all the years. The vegetation cover is densely replenished around the dams and natural water bodies which serve as the

  13. Caracterización y monitoreo de paisaje semiárida en la Región del Maule mediante datos satelitales Characterization and monitoring of semi-arid landscape in the Maule region from satellite data

    Directory of Open Access Journals (Sweden)

    Carlos M. Frau


    Full Text Available El objetivo del trabajo es aplicar la técnica Rotación Radiométrica Controlada por Eje de No-cambio (RCEN en imágenes Landsat TM de los años 2004 y 2008, para la región semi-árida del Maule, Chile. Esta aplicación tiene el fin de obtener la distribución espacial de los cambios del paisaje forestal. El procedimiento de RCEN permite el uso de imágenes sin corrección atmosférica, combinado a un método empírico para seccionar y legendar la imagen de cambio basado en las observaciones de campo. El índice Kappa para la imagen temática del cambio fue 0.74 indicando que, durante el período considerado por la detección, los porcentajes de recuperación y la degradación la vegetación fueron 17 y 5% respectivamente. Datos altimétricos de SRTM (Shuttle Radar Topography Mission fueron utilizados para obtener la pendiente y la distribución de las clases de cambios en relación a esta. La mayor parte de la superficie de la clase no-cambio está localizada en altas y bajas declividades. En la categoría de recuperación de la vegetación, la mayor proporción tiene lugar en el rango de declividad 10 a 50%. Por otra parte, la pérdida de vegetación es uniformemente distribuida en todos los gradientes de declividad.The objective of this research is to apply the Radiometric Rotation Controlled by No-change Axis (RCNA technique on Landsat TM images, 2004 and 2008, covering the coastal dry land of the Region of Maule, Chile, in order to obtain the spatial distribution of changes and degradation in the forest landscape. The RCNA procedure allows the use of images without atmospheric calibrations, whose empirical method for the label was based on field observations. The Kappa Index for the change thematic image was 0.74, showing that the recovery and loss of vegetation were 17 and 5%, respectively. SRTM (Shuttle Radar Topography Mission data were used to derive slope angle, where the major proportion of no-change surface occurs in areas of high

  14. ENSO elicits opposing responses of semi-arid vegetation between Hemispheres (United States)

    Zhang, Anzhi; Jia, Gensuo; Epstein, Howard E.; Xia, Jiangjiang


    Semi-arid ecosystems are key contributors to the global carbon cycle and may even dominate the inter-annual variability (IAV) and trends of the land carbon sink, driven largely by the El Niño–Southern Oscillation (ENSO). The linkages between dynamics of semi-arid ecosystems and climate at the hemispheric scale however are not well known. Here, we use satellite data and climate observations from 2000 to 2014 to explore the impacts of ENSO on variability of semi-arid ecosystems, using the Ensemble Empirical Mode Decomposition method. We show that the responses of semi-arid vegetation to ENSO occur in opposite directions, resulting from opposing controls of ENSO on precipitation between the Northern Hemisphere (positively correlated to ENSO) and the Southern Hemisphere (negatively correlated to ENSO). Also, the Southern Hemisphere, with a robust negative coupling of temperature and precipitation anomalies, exhibits stronger and faster responses of semi-arid ecosystems to ENSO than the Northern Hemisphere. Our findings suggest that natural coherent variability in semi-arid ecosystem productivity responded to ENSO in opposite ways between two hemispheres, which may imply potential prediction of global semi-arid ecosystem variability, particularly based on variability in tropical Pacific Sea Surface Temperatures. PMID:28181570

  15. ENSO elicits opposing responses of semi-arid vegetation between Hemispheres. (United States)

    Zhang, Anzhi; Jia, Gensuo; Epstein, Howard E; Xia, Jiangjiang


    Semi-arid ecosystems are key contributors to the global carbon cycle and may even dominate the inter-annual variability (IAV) and trends of the land carbon sink, driven largely by the El Niño-Southern Oscillation (ENSO). The linkages between dynamics of semi-arid ecosystems and climate at the hemispheric scale however are not well known. Here, we use satellite data and climate observations from 2000 to 2014 to explore the impacts of ENSO on variability of semi-arid ecosystems, using the Ensemble Empirical Mode Decomposition method. We show that the responses of semi-arid vegetation to ENSO occur in opposite directions, resulting from opposing controls of ENSO on precipitation between the Northern Hemisphere (positively correlated to ENSO) and the Southern Hemisphere (negatively correlated to ENSO). Also, the Southern Hemisphere, with a robust negative coupling of temperature and precipitation anomalies, exhibits stronger and faster responses of semi-arid ecosystems to ENSO than the Northern Hemisphere. Our findings suggest that natural coherent variability in semi-arid ecosystem productivity responded to ENSO in opposite ways between two hemispheres, which may imply potential prediction of global semi-arid ecosystem variability, particularly based on variability in tropical Pacific Sea Surface Temperatures.

  16. Impacts of intensive agricultural irrigation and livestock farming on a semi-arid Mediterranean catchment. (United States)

    Martín-Queller, Emi; Moreno-Mateos, David; Pedrocchi, César; Cervantes, Juan; Martínez, Gonzalo


    Irrigation return flows (IRF) are a major contributor of non-point source pollution to surface and groundwater. We evaluated the effects of irrigation on stream hydrochemistry in a Mediterranean semi-arid catchment (Flumen River, NE Spain). The Flumen River was separated into two zones based on the intensity of irrigation activities in the watershed. General linear models were used to compare the two zones. Relevant covariables (urban sewage, pig farming, and gypsum deposits in the basin) were quantified with the help of geographic information system techniques, accompanied by ground-truthing. High variability of the water quality parameters and temporal dynamics caused by irrigation were used to distinguish the two river reaches. Urban activity and livestock farming had a significant effect on water chemistry. An increase in the concentration of salts (240-541 more in winter) and nitrate (average concentrations increased from 8.5 to 20.8 mg.l(-1) during irrigation months) was associated with a higher level of IRF. Those river reaches more strongly influenced by urban areas tended to have higher phosphorus (0.19-0.42 mg.l(-1) more in winter) concentrations. These results support earlier research about the significant consequences to water quality of both urban expansion and intensive agricultural production in arid and semi-arid regions. Data also indicate that salinization of soils, subsoils, surface water, and groundwater can be an unwelcome result of the application of pig manure for fertilization (increase in sodium concentration in 77.9 to 138.6 mg.l(-1)).

  17. When does colonisation of a semi-arid hillslope generate vegetation patterns? (United States)

    Sherratt, Jonathan A


    Patterned vegetation occurs in many semi-arid regions of the world. Most previous studies have assumed that patterns form from a starting point of uniform vegetation, for example as a response to a decrease in mean annual rainfall. However an alternative possibility is that patterns are generated when bare ground is colonised. This paper investigates the conditions under which colonisation leads to patterning on sloping ground. The slope gradient plays an important role because of the downhill flow of rainwater. One long-established consequence of this is that patterns are organised into stripes running parallel to the contours; such patterns are known as banded vegetation or tiger bush. This paper shows that the slope also has an important effect on colonisation, since the uphill and downhill edges of an isolated vegetation patch have different dynamics. For the much-used Klausmeier model for semi-arid vegetation, the author shows that without a term representing water diffusion, colonisation always generates uniform vegetation rather than a pattern. However the combination of a sufficiently large water diffusion term and a sufficiently low slope gradient does lead to colonisation-induced patterning. The author goes on to consider colonisation in the Rietkerk model, which is also in widespread use: the same conclusions apply for this model provided that a small threshold is imposed on vegetation biomass, below which plant growth is set to zero. Since the two models are quite different mathematically, this suggests that the predictions are a consequence of the basic underlying assumption of water redistribution as the pattern generation mechanism.

  18. optimization of water resources allocation in semi-arid region

    African Journals Online (AJOL)

    Eng Obi Ibeje

    basically due to allocation of water for various industrial purposes like product processing, cooling of machines, washing of plants and other diverse industrial applications are classified as industrial returns. The allocations from the dam are jointly pumped as town water supply; no separate meters were available to measure.

  19. Adaptation at Scale in Semi-arid Regions (ASSAR)

    International Development Research Centre (IDRC) Digital Library (Canada)

    Microsoft Office User

    Develop and trial relevant and actionable strategies for adaptation. • Innovative communication approaches for effective knowledge sharing on climate change vulnerability and adaptation in SARs. • Capacity strengthening for adaptation in SARs, in research, policy and practice domains. • ASSAR research is used well ...

  20. Safeguarding semi-arid regions from climate shocks | IDRC ...

    International Development Research Centre (IDRC) Digital Library (Canada)


    Apr 21, 2016 ... The panel took place during the Our Common Future Under Climate Change conference, the largest climate science forum in advance of the COP21 climate summit. In the Indian tropics, knowledge gaps around social vulnerability still exist, said Andaleeb Rahman of the Indian Institute for Human ...

  1. KAJIAN PEMENUHAN KEBUTUHAN AIR MINUM UNTUK MASYARAKAT DI KAWASAN SEMI-ARID INDONESIA (A Study on Fulfillment of Drinking Water Need of People in Semi-Arid Areas in Indonesia

    Directory of Open Access Journals (Sweden)

    Jakobis Johanis Messakh


    Full Text Available ABSTRAK Kawasan Kota Kupang dan sekitarnya saat ini berkembang menjadi pusat perekonomian, pendidikan dan sosial budaya di NTT, dengan laju permintaan kebutuhan air minum yang tinggi. Tantangan penyediaan air minum semakin besar, karena daerah tersebut merupakan kawasan semi-arid di Indonesia yang memiliki keterbatasan ketersediaan dan kontinuitas air dari berbagai sumber air yang ada. Penelitian ini bertujuan untuk menganalisa pemenuhan kebutuhan air minum bagi masyarakat di kawasan semi-arid Indonesia, khususnya Regional Kupang, tahun 2015-2035. Penelitian dibagi atas tiga tahap, yakni tahap pertama mengkaji proyeksi laju permintaan air minum tahun 2015-2035, tahap kedua melakukan identifikasi potensi sumber air tersedia, dan tahap ketiga mengatur skenario pemenuhan kebutuhan air minum. Hasil penelitian menunjukkan bahwa, potensi sumber air yang ada, sulit untuk memenuhi kebutuhan air minum pada rentang waktu perencanaan 2015-2035, khususnya mulai tahun 2019 dengan target pencapaian pelayanan air minum harus mencapai 100%. Untuk mengatasi hal ini maka, paradigma pengelolaan sumber daya air untuk keperluan multisektor perlu disesuaikan menurut kekhasan kawasan semi-arid, dengan prioritas utama untuk kebutuhan air minum. Potensi curah hujan yang terjadi perlu dioptimalkan pemanfaatannya sebagai sumber air baku, melalui pembangunan waduk, sarana penampungan air hujan lainnya dan disertai upaya konservasi. Penghematan penggunaan air sesuai kebutuhan dan kearifan lokal daerah, serta pengaturan prioritas daerah pelayanan untuk sistem perpipaan air minum, merupakan strategi lainnya yang bisa dilakukan. Penggunaan air tanah yang merupakan sumber air baku utama, harus dikendalikan dengan mempertimbangkan daya dukung lingkungan. ABSTRACT Kupang and its surrounding region are currently developing into a center of economy, education and socio-culture in the NTT province, with a high rate of demand for drinking water. The challenge to provide drinking

  2. Antiproliferative Activity, Antioxidant Capacity and Tannin Content in Plants of Semi-Arid Northeastern Brazil  

    Directory of Open Access Journals (Sweden)

    Silene Carneiro do Nascimento


    Full Text Available The objective of this study was to evaluate antiproliferative activity, antioxidant capacity and tannin content in plants from semi-arid northeastern Brazil (Caatinga. For this study, we selected 14 species and we assayed the methanol extracts for antiproliferative activity against the HEp-2 (laryngeal cancer and NCI-H292 (lung cancer cell lines using the (3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazole (MTT method. In addition, the antioxidant activity was evaluated with the DPPH (2,2-diphenyl-2-picrylhydrazyl assay, and the tannin content was determined by the radial diffusion method. Plants with better antioxidant activity (expressed in a dose able to decrease the initial DPPH concentration by 50%, or IC50 and with higher levels of tannins were: Poincianella pyramidalis (42.95 ± 1.77 µg/mL IC50 and 8.17 ± 0.64 tannin content, Jatropha mollissima (54.09 ± 4.36µg/mL IC50 and 2.35 ± 0.08 tannin content and Anadenanthera colubrina (73.24 ± 1.47 µg/mL IC50 and 4.41 ± 0.47 tannin content. Plants with enhanced antiproliferative activity (% living cells were Annona muricata (24.94 ± 0.74 in NCI-H292, Lantana camara (25.8 ± 0.19 in NCI-H292, Handroanthus impetiginosus (41.8 ± 0.47 in NCI-H292 and Mentzelia aspera (45.61 ± 1.94 in HEp-2. For species with better antioxidant and antiproliferative activities, we suggest future in vitro and in vivo comparative studies with other pharmacological models, and to start a process of purification and identification of the possible molecule(s responsible for the observed pharmacological activity. We believe that the flora of Brazilian semi-arid areas can be a valuable source of plants rich in tannins, cytotoxic compounds and antioxidant agents.

  3. Groundwater Recharge Rates and Surface Runoff Response to Land Use and Land Cover Changes in Semi-arid Environments (United States)

    Owuor, Steven; Butterbach-Bahl, Klaus; Guzha, Alphonce; Rufino, Mariana; Pelster, David; Díaz-Pinés, Eugenio; Breuer, Lutz; Merbold, Lutz


    Conclusive evidence and understanding of the effects of land use and land cover (LULC) on both groundwater recharge and surface runoff is critical for effective management of water resources in semi-arid region as those heavily depend on groundwater resources. However, there is limited quantitative evidence on how changes to LULC in semi-arid tropical and subtropical regions affect the subsurface components of the hydrologic cycle, particularly groundwater recharge. In this study, we reviewed a total of 27 studies (2 modelling and 25 experimental), which reported on pre- and post-land use change groundwater recharge or surface runoff magnitude, and thus allowed to quantify the response of groundwater recharge rates and runoff to LULC. Restoration of bare land induces a decrease in groundwater recharge from 42 % of precipitation to between 6 and 12 % depending on the final LULC. If forests are cleared for rangelands, groundwater recharge increases by 7.8 ± 12.6 %, while conversion to cropland or grassland results in increases of 3.4 ± 2.5 and 4.4 ± 3.3 %, respectively. Rehabilitation of bare land to cropland results in surface runoff reductions of between 5.2 and 7.3 %. The conversion of forest vegetation to managed LULC shows an increase in surface runoff from 1 to 14.1 % depending on the final LULC. Surface runoff is reduced from 2.5 to 1.1 % when grassland is converted to forest vegetation. While there is general consistency in the results from the selected case studies, we conclude that there are few experimental studies that have been conducted in tropical and subtropical semi-arid regions, despite that many people rely heavily on groundwater for their livelihoods. Therefore, there is an urgent need to increase the body of quantitative evidence given the pressure of growing human population and climate change on water resources in the region.

  4. Acclimation of Pistacia integerrima trees to frost in semi-arid environments depends on autumn's drought. (United States)

    Sperling, Or; Secchi, Francesca; Godfrey, Jessie; Zwieniecki, Maciej A


    Main conclusion Cold acclimation is revealed through induced stem respiration during pre-winter frost of native Pistacia integerrima trees in continental semi-arid environments. Semi-arid environments challenge vegetation by simultaneous abiotic stresses. In this study, we examine the combined effects of water stress and frost on the physiology of Pistacia integerrima stems. This species is native to semi-arid environments where drought and frost frequently co-occur. We quantified carbohydrates and proline in P. integerrima stems responding to frost and experiencing water potentials between -0.2 and -1.8 MPa. We report that dehydrated trees (i.e., Ψstem semi-arid environments.

  5. Ethno-ornithology and conservation of wild birds in the semi-arid Caatinga of northeastern Brazil (United States)


    The utilization of birds as pets has been recognized as one of the principal threats to global avifauna. Most of the information about the use and sale of birds as pets has been limited to areas of high biodiversity and whose impacts of anthropic actions have been widely broadcast internationally, for example for the Amazon Forest and forest remnants of Southeast Asia. The Caatinga predominates in the semi-arid region of Brazil, and is one of the semi-arid biomes with the greatest biological diversity in the world, where 511 species of birds exist. Many of these birds are used as pets, a common practice in the region, which has important conservationist implications but has been little studied. Therefore, the aim of the present study was to detail aspects of the use of birds as pets in a locality in the semi-arid region of Northeast Brazil. Information on the use of avifauna was obtained through interviews and visits to the homes of 78 wild bird keepers. A total of 41 species of birds were recorded, mostly of the families Emberizidae (n = 9 species), Columbidae (n = 7 species), Icteridae (n = 6 species) and Psittacidae (n = 3 species). The birds that were most often recorded were Paroaria dominicana (n = 79 especimens), Sporophila albogularis (n = 67), Aratinga cactorum (n = 49), Sporophila lineola (n = 36), Sicalis flaveola (n = 29) and Sporophila nigricollis (n = 27). The use of wild birds in the area studied, as an example of what occurs in other places in the semi-arid Northeast, demonstrates that such activities persist in the region, in spite of being illegal, and have been happening in clandestine or semi-clandestine manner. No statistically significant correlation were found between socioeconomic factors and keeping birds as pets reflects the cultural importance of this practice of rearing wild birds for pets in the region, which is widespread among the local population, independent of socioeconomic factors. Obviously

  6. Evaluating water controls on vegetation growth in the semi-arid sahel using field and earth observation data

    DEFF Research Database (Denmark)

    Abdi, Abdulhakim M.; Boke-Olen, Niklas; Tenenbaum, David E.


    Water loss is a crucial factor for vegetation in the semi-arid Sahel region of Africa. Global satellite-driven estimates of plant CO2 uptake (gross primary productivity, GPP) have been found to not accurately account for Sahelian conditions, particularly the impact of canopy water stress. Here, we...... identify the main biophysical limitations that induce canopy water stress in Sahelian vegetation and evaluate the relationships between field data and Earth observation-derived spectral products for up-scaling GPP. We find that plant-available water and vapor pressure deficit together control the GPP...


    Directory of Open Access Journals (Sweden)

    E. O. Adam


    Full Text Available The arid and semi-arid catchments in dry lands in general require a special effective management as the scarcity of resources and information which is needed to leverage studies and investigations is the common characteristic. Hydrology is one of the most important elements in the management of resources. Deep understanding of hydrological responses is the key towards better planning and land management. Surface runoff quantification of such ungauged semi-arid catchments considered among the important challenges. A 7586 km2 catchment under investigation is located in semi-arid region in central Sudan where mean annual rainfall is around 250 mm and represent the ultimate source for water supply. The objective is to parameterize hydrological characteristics of the catchment and estimate surface runoff using suitable methods and hydrological models that suit the nature of such ungauged catchments with scarce geospatial information. In order to produce spatial runoff estimations, satellite rainfall was used. Remote sensing and GIS were incorporated in the investigations and the generation of landcover and soil information. Five days rainfall event (50.2 mm was used for the SCS CN model which is considered the suitable for this catchment, as SCS curve number (CN method is widely used for estimating infiltration characteristics depending on the landcover and soil property. Runoff depths of 3.6, 15.7 and 29.7 mm were estimated for the three different Antecedent Moisture Conditions (AMC-I, AMC-II and AMC-III. The estimated runoff depths of AMCII and AMCIII indicate the possibility of having small artificial surface reservoirs that could provide water for domestic and small household agricultural use.

  8. Aquatic systems in semi-arid Brazil: limnology and management Ecossistemas aquáticos do semi-árido brasileiro: aspectos limnológicos e manejo

    Directory of Open Access Journals (Sweden)

    José Etham de Lucena Barbosa


    Full Text Available Aquatic systems in semi-arid Brazil include natural shallow lakes, artificial reservoirs and intermittent streams and rivers. These systems are distinctive features in the semi-arid landscape and comprise a range of associated systems functioning as an ever-changing mosaic of dry/wet patches. Lakes and reservoirs in semi-arid Brazil are subject to important periods of water shortages, whereas rivers and streams are characterized as highly variable and driven by the extremes of water flow and its absence. Within this view a catchment-scale approach must be used to create a holistic model to conceptualize and comprehend these aquatic systems, since the aquatic environment types in the semi-arid region of Brazil incorporate broader aspects within the catchment scale such as geomorphology, vegetation, climate and land use. This paper summarizes some of the information on the aquatic systems of the Brazilian semi-arid region and shows the importance of limnological studies in this region. It also attempts to establish perspectives for future research considering the catchment as a scale for surveying biological processes and limnological characteristics of the various aquatic systems. It is presented information on their overall structure and functioning, as well as characteristics of some biological communities, such as phytoplankton, periphyton, aquatic macrophytes, benthic invertebrates and fish. The importance of the understanding of eutrophication in reservoirs and the role of the dry phase in streams is emphasized, and information on possible actions of planning and management to improve water quality of reservoirs are presented.Os ecossistemas no semiárido brasileiro englobam lagos rasos naturais, reservatórios artificiais e rios e riachos intermitentes. Estes sistemas são particularidades na paisagem do semiárida e compreendem uma grande variedade de sistemas associados, funcionando como um mosaico em constante mudança entre épocas de

  9. Biogeochemical factors contributing to enhanced carbon storage following afforestation of a semi-arid shrubland

    Directory of Open Access Journals (Sweden)

    J. M. Grünzweig


    Full Text Available Ecosystems in dry regions are generally low in productivity and carbon (C storage. We report, however, large increases in C sequestration following afforestation of a semi-arid shrubland with Pinus halepensis trees. Using C and nitrogen (N inventories, based in part on site-specific allometric equations, we measured an increase in the standing ecosystem C stock from 2380 g C m−2 in the shrubland to 5840 g C m−2 in the forest after 35 years, with no significant change in N stocks. Carbon sequestration following afforestation was associated with increased N use efficiency as reflected by an overall increase in C/N ratio from 7.6 in the shrubland to 16.6 in the forest. The C accumulation rate in the forest was particularly high for soil organic C (SOC; increase of 1760 g C m−2 or 50 g C m−2 yr−1, which was associated with the following factors: 1 Analysis of a small 13C signal within this pure C3 system combined with size fractionation of soil organic matter indicated a significant addition of new SOC derived from forest vegetation (68% of total forest SOC and a considerable portion of the old original shrubland SOC (53% still remaining in the forest. 2 A large part of both new and old SOC appeared to be protected from decomposition as about 60% of SOC under both land-use types were in mineral-associated fractions. 3 A short-term decomposition study indicated decreased decomposition of lower-quality litter and SOC in the forest, based on reduced decay rates of up to 90% for forest compared to shrubland litter. 4 Forest soil included a significant component of live and dead roots (12% of total SOC. Our results suggest a role for increased N use efficiency, enhanced SOC protection and reduced decomposition rates in the large C sequestration potential following afforestation in semi-arid regions. These results are particularly relevant in light of persistent

  10. Atributos químicos de solos sob diferentes usos em perímetro irrigado no semiárido de Pernambuco Soil chemical properties under different uses in an irrigated area in the semi arid region of Pernambuco, Brazil

    Directory of Open Access Journals (Sweden)

    Rossini Mattos Corrêa


    salinização do solo, tornando suas utilizações agrícolas menos sustentáveis.Soils developed at semi-arid climate can present salt accumulation, which compromise the agricultural use, being increased by inadequate irrigation management. Based on the use, the degradation of these soils can occur at higher or smaller intensity. This study aimed to evaluate the effect of soil uses based on physical and chemical properties of an irrigated area in the semi-arid region of northeastern Brazil. The soil uses were annual crops (C, fruticulture (F, pasture (P, discarded lands (D, or native vegetation (V. Disturbed soil samples were collected from the 0-10, 10-30 and 30-60 cm layers for chemical analysis, and undisturbed samples from the first two layers for soil density analysis. The indicators pH and electrical conductivity of the saturation extract, soil pH, available phosphorus, total organic carbon, exchangeable cations, calcium, magnesium, potassium, and sodium, cation exchange capacity, sum of bases, base saturation percentage, percentage of exchangeable sodium, and carbon stocks were subjected to multivariate analysis by Principal Component Analysis, and clustering by the Tocher method. The soil chemical properties under production systems was different from V; the chemical quality of the production systems C and D, and that of C and P was similar. For the uses C, D, P, and F, the values of the soil properties (pH, pH and electrical conductivity of the saturation extract, exchangeable calcium and magnesium, sum of bases, base saturation and available phosphorus was higher than for V in the three analyzed layers. The highest total organic carbon content was observed under F and P. The electrical conductivity of the saturation extract was higher under C, D and P than under F and V, indicating the beginning of a soil salinization process, thus characterizing them as less sustainable land uses.

  11. Soil bacterial community responses to revegetation of moving sand dune in semi-arid grassland. (United States)

    Cao, Chengyou; Zhang, Ying; Cui, Zhenbo; Feng, Shuwei; Wang, Tingting; Ren, Qing


    the native soil of NC, suggesting that the plantation type and soil properties exhibit a minimal effect on the compositions of soil microbial communities within a continuous landscape. These results revealed that the structure of the soil bacterial community of degraded sandy grassland (even degenerated into a mobile sand dunes) in semi-arid region can be reversibly restored by planting indigenous shrub or semi-shrub plantation on human time scales.

  12. Applying an Avian Index of Biological Integrity to Assess and Monitor Arid and Semi-arid Riparian Ecosystems (United States)


    ERDC TN-EMRRP-RQ-01 January 2009 Applying an Avian Index of Biological Integrity to Assess and Monitor Arid and Semi - arid Riparian Ecosystems by...00-2009 to 00-00-2009 4. TITLE AND SUBTITLE Applying an Avian Index of Biological Integrity to Assess and Monitor Arid and Semi - arid Riparian...biological integrity to assess and monitor arid and semi - arid riparian eco- systems. EMRRP Technical Notes Collection (ERDC TN-EMRRP-RQ-01). Vicksburg, MS

  13. Mapping the variation of soil organic carbon (SOC) stock in time and space in Sicily, an extremely variable semi-arid Mediterranean region, highlighted that C was lost in area rich in organic C and gained in poor-C areas (United States)

    Schillaci, Calogero; Acutis, Marco; Lombardo, Luigi; Lipani, Aldo; Fantappiè, Maria; Märker, Michael; Saia, Sergio


    The stock of organic carbon in the soil (SOC) is an indicator of soil ability to support agro-ecosystems productivity and resilience to environmental changes (Schillaci et al. 2016; 2017). In addition, SOC stock change through space and especially time is a valuable indicator of the soil ability to sequester CO2 from the atmosphere and thus its potential to reduce the greenhouse gas effect. In the present work, we mapped (1-km resolution) the space-time variation of the SOC stock after 15 years (1993 to 2008) in a semi-arid Mediterranean area (25,286 km2) after modelling SOC concentration (0-0.4 m depth) with boosted regression trees (BRT) and computing the SOC stock after the application of the bulk density maps of ISRIC (, Hengl et al., 2014). The area under study (Sicily, south of Italy) has a plenty of contrasting environments, with changing ecosystems, soils, and microclimatic regions. The BRT procedure was run with a set of 25 predictors per year, including land use, soil traits, morphometric indicators and remote sensing covariates (derived from Landsat5 data). The BRT output consisted of a high pseudo-R2(=0.71 for 1993 and 0.63 for 2008) of the SOC concentration, low uncertainty (standard deviation mountainous environments with high initial SOC stock and extensively used for forestry. This decrease was likely due to both high erosion rates and a short-term change in the climate, especially temperature. A high and positive percentage variation of the SOC stock (+39.1 % to +180.0%, corresponding to the data higher than the mean+s.d.) was found in 14.3% of the area under study. These environments are dominated by non-irrigated arable lands and characterized by low SOC, low rainfall and high temperature. In these conditions, the increase of the SOC stock found in 15 years likely occurred to the compulsory application of some Good Agricultural and Environmental Conditions, some of which were compulsory during the study period. Despite the mean SOC

  14. Retorno econômico do aproveitamento de resíduos gerados na produção de frutas no semiárido cearense = Economic return of the residues generated in fruit production in the semi-arid region of Ceará

    Directory of Open Access Journals (Sweden)

    Ariana Carvalho Pinto


    Full Text Available O reaproveitamento dos resíduos plásticos pode se tornar uma atividade agrícola economicamente viável, principalmente na fruticultura localizada no semiárido cearense. Os materiais nos quais eram tidos como lixo nas áreas agrícolas podem ser uma fonte alternativa de geração de capital e empregos para a região, utilizando-se técnicas de reaproveitamento e reciclagem desses materiais. O objetivo deste trabalho foi avaliar a importância e a viabilidade econômica da reutilização dos materiais plásticos empregados diretamente na fruticultura. Os dados foram coletados de uma empresa agrícola de fruticultura e de uma empresa de reciclagem no município de Icapuí, no estado do Ceará. Foram calculados indicadores de viabilidade financeira como Valor Presente Líquido [VPL], Taxa Interna de Retorno [TIR], Payback simples [PB], Payback descontado [PBD]. Os resultados mostraram que a utilização de técnicas e equipamentos de reciclagem em empresas é um caminho que gera muitas oportunidades de reutilização de materiais antes descartados, bem como a viabilidade econômica, confirmada pelos valores obtidos de VPL (R$ 529.777,58 e TIR de 31%. Conforme o cálculo do Payback descontado, serão necessários dois anos e quatro meses para recuperar o investimento dos fluxos líquidos de caixa descontados. Conclui-se que a atividade é sustentável e rentável, trazendo benefícios e lucro ao fruticultor, além de disponibilizar empregos diretos e indiretos. = The reuse of plastic can become an economically viable agricultural activity, mainly in the fruticulture located in the semi-arid region of Ceará. The materials in which they were treated as garbage in the agricultural areas can be an alternative source of capital generation and jobs for the region, using reuse and recycling techniques. The objective of this work was to evaluate the importance and economic viability of the reuse of plastic materials used directly in the fruticulture

  15. Interaction of water components in the semi-arid Huasco and Limarí river basins, North Central Chile (United States)

    Strauch, G.; Oyarzún, R.; Reinstorf, F.; Oyarzún, J.; Schirmer, M.; Knöller, K.


    For sustainable water resource management in semi-arid regions, sound information is required about interactions between the different components of the water system: rain/snow precipitation, surface/subsurface run-off, groundwater recharge. Exemplarily, the Huasco and Limarí river basins as water stressed river catchments have been studied by isotope and hydrochemical methods for (i) the origin of water, (ii) water quality, (iii) relations of surface and groundwater. Applying the complex multi-isotopic and hydrochemical methodology to the water components of the Huasco and Limarí basins, a differentiation of water components concerning subsurface flow and river water along the catchment area and by anthropogenic impacts are detected. Sulphate and nitrate concentrations indicate remarkable input from mining and agricultural activities along the river catchment. The 2H-18O relations of river water and groundwater of both catchments point to the behaviour of river waters originated in an arid to semi-arid environment. Consequently, the groundwater from several production wells in the lower parts of the catchments is related to the rivers where the wells located, however, it can be distinguished from the river water. Using the hydrological water balance and the isotope mixing model, the interaction between surface and subsurface flows and river flow is estimated.

  16. Fixation kinetics of chelated and non-chelated zinc in semi-arid alkaline soils: application to zinc management (United States)

    Udeigwe, Theophilus K.; Eichmann, Madeleine; Menkiti, Matthew C.


    This study was designed to examine the fixation pattern and kinetics of zinc (Zn) in chelated (ethylenediaminetetraacetic acid, EDTA) and non-chelated mixed micronutrient systems of semi-arid alkaline soils from the Southern High Plains, USA. Soils were characterized for a suite of chemical and physical properties and data obtained from extraction experiments fitted to various kinetic models. About 30 % more plant-available Zn was fixed in the non-chelated system within the first 14 days with only about 18 % difference observed between the two systems by day 90, suggesting that the effectiveness of the chelated compounds tended to decrease over time. The strengths of the relationships of change in available Zn with respect to other micronutrients (copper, iron, and manganese) were higher and more significant in the non-chelated system (average R2 of 0.83), compared to the chelated (average R2 of 0.42). Fixation of plant-available Zn was best described by the power-function model (R2 = 0.94, SE = 0.076) in the non-chelated system, and was poorly described by all the models examined in the chelated system. Reaction rate constants and relationships generated from this study can serve as important tools for micronutrient management and for future micronutrient modeling studies on these soils and other semi-arid regions of the world.

  17. Mapping ecological processes and ecosystem services for prioritizing restoration efforts in a semi-arid Mediterranean river basin. (United States)

    Trabucchi, Mattia; O'Farrell, Patrick J; Notivol, Eduardo; Comín, Francisco A


    Semi-arid Mediterranean regions are highly susceptible to desertification processes which can reduce the benefits that people obtain from healthy ecosystems and thus threaten human wellbeing. The European Union Biodiversity Strategy to 2020 recognizes the need to incorporate ecosystem services into land-use management, conservation, and restoration actions. The inclusion of ecosystem services into restoration actions and plans is an emerging area of research, and there are few documented approaches and guidelines on how to undertake such an exercise. This paper responds to this need, and we demonstrate an approach for identifying both key ecosystem services provisioning areas and the spatial relationship between ecological processes and services. A degraded semi-arid Mediterranean river basin in north east Spain was used as a case study area. We show that the quantification and mapping of services are the first step required for both optimizing and targeting of specific local areas for restoration. Additionally, we provide guidelines for restoration planning at a watershed scale; establishing priorities for improving the delivery of ecosystem services at this scale; and prioritizing the sub-watersheds for restoration based on their potential for delivering a combination of key ecosystem services for the entire basin.

  18. Overlap in nitrogen sources and redistribution of nitrogen between trees and grasses in a semi-arid savanna. (United States)

    Priyadarshini, K V R; Prins, Herbert H T; de Bie, Steven; Heitkönig, Ignas M A; Woodborne, Stephan; Gort, Gerrit; Kirkman, Kevin; Fry, Brian; de Kroon, Hans


    A key question in savanna ecology is how trees and grasses coexist under N limitation. We used N stable isotopes and N content to study N source partitioning across seasons from trees and associated grasses in a semi-arid savanna. We also used (15)N tracer additions to investigate possible redistribution of N by trees to grasses. Foliar stable N isotope ratio (δ(15)N) values were consistent with trees and grasses using mycorrhiza-supplied N in all seasons except in the wet season when they switched to microbially fixed N. The dependence of trees and grasses on mineralized soil N seemed highly unlikely based on seasonal variation in mineralization rates in the Kruger Park region. Remarkably, foliar δ(15)N values were similar for all three tree species differing in the potential for N fixation through nodulation. The tracer experiment showed that N was redistributed by trees to understory grasses in all seasons. Our results suggest that the redistribution of N from trees to grasses and uptake of N was independent of water redistribution. Although there is overlap of N sources between trees and grasses, dependence on biological sources of N coupled with redistribution of subsoil N by trees may contribute to the coexistence of trees and grasses in semi-arid savannas.

  19. Damage caused to the environment by reforestation policies in arid and semi-arid areas of China. (United States)

    Cao, Shixiong; Tian, Tao; Chen, Li; Dong, Xiaobin; Yu, Xinxiao; Wang, Guosheng


    Traditional approaches to ecosystem restoration have considered afforestation to be an important tool. To alleviate land degradation in China, the Chinese government has therefore invested huge amounts of money in planting trees. However, the results of more than half a century of large-scale afforestation in arid and semi-arid China have shown that when the trees are not adapted to the local environment, the policy does not improve the environment, and may instead increase environmental degradation. When precipitation is lower than potential evaporation, surface soil moisture typically cannot sustain forest vegetation, and shrubs or steppe species replace the forest to form a sustainable natural ecosystem that exists in a stable equilibrium with the available water supply. The climate of much of northwestern China appears to be unsuitable for afforestation owing to the extremely low rainfall. Although some small-scale or short-term afforestation efforts have succeeded in this region, many of the resulting forests have died or degraded over longer periods, so policymakers must understand that these small-scale or short-term results do not support an inflexible policy of large-scale afforestation throughout arid and semi-arid northwestern China. Rather than focusing solely on afforestation, it would be more effective to attempt to recreate natural ecosystems that are better adapted to local environments and that thus provide a better chance of sustainable, long-term rehabilitation.

  20. Quality of urban runoff in wet and dry seasons: a case study in a semi-arid zone. (United States)

    Ortiz-Hernández, Joyce; Lucho-Constantino, Carlos; Lizárraga-Mendiola, Liliana; Beltrán-Hernández, Rosa Icela; Coronel-Olivares, Claudia; Vázquez-Rodríguez, Gabriela


    Urban runoff (UR) is a promising new resource that may alleviate growing tensions in numerous arid and semi-arid regions of the world. However, it is precisely in these zones that the available UR quality characteristics are scarcer. This work aims to evaluate a wide set of parameters to establish a detailed approach to both the quality of UR in a midsized city in Central Mexico and the feasibility of using UR to recharge aquifers. UR from an institutional land use site was sampled during wet and dry seasons and assessed for suspended solids, organic matter, nutrients, microorganisms, metals, and persistent organic chemicals (i.e., polycyclic aromatic hydrocarbons, PAH). The results were analyzed using multivariate statistical methods to identify relationships among the variables, the sampling sites and the seasons. The soil erosion and the leaching of materials due to the water flow through vegetated areas were identified as the most influencing factor on the quality of the site runoff in both dry and wet seasons. Additionally, data were more heterogeneous during the dry season, and higher pollutant concentrations were found both during the dry season and in more pervious zones. We consider UR a promising water source for recharging aquifers in arid and semi-arid zones if a program is implemented that can integrate an adequate runoff treatment system, soil protection, and other non-structural measures.

  1. Impact of seasonal changes on fungal diversity of a semi-arid ecosystem revealed by 454 pyrosequencing. (United States)

    Vargas-Gastélum, Lluvia; Romero-Olivares, Adriana L; Escalante, Ana E; Rocha-Olivares, Axayácatl; Brizuela, Carlos; Riquelme, Meritxell


    Fungi play fundamental ecological roles in terrestrial ecosystems. However, their distribution and diversity remain poorly described in natural communities, particularly in arid and semi-arid ecosystems. In order to identify environmental factors determining fungal community structure in these systems, we assessed their diversity in conjunction with soil physicochemical characteristics in a semi-arid ecosystem in Baja California, Mexico, endemic for Coccidioidomycosis (Valley Fever). Two different microhabitats, burrows (influenced by rodent activity) and topsoil, were compared in winter and summer. Using a metagenomic approach, the ITS1 region of nuclear ribosomal DNA was used as barcode. A total of 1940 Operational Taxonomic Units (OTUs) were identified from 362 332 ITS1 sequences obtained by 454 pyrosequencing. Differences in fungal composition between seasons were clearly identified. Moreover, differences in composition between microhabitats were mainly correlated to significant differences in environmental factors, such as moisture and clay content in topsoil samples, and temperature and electrical conductivity in burrow samples. Overall, the fungal community structure (dominated by Ascomycota and Basidiomycota) was less variable between seasons in burrow than in topsoil samples. Coccidioides spp. went undetected by pyrosequencing. However, a nested PCR approach revealed its higher prevalence in burrows. © FEMS 2015. All rights reserved. For permissions, please e-mail:

  2. Roots of forbs sense climate fluctuations in the semi-arid Loess Plateau: Herb-chronology based analysis. (United States)

    Shi, Songlin; Li, Zongshan; Wang, Hao; von Arx, Georg; Lü, Yihe; Wu, Xing; Wang, Xiaochun; Liu, Guohua; Fu, Bojie


    Growth of herbaceous plants responds sensitively and rapidly to climate variability. Yet, little is known regarding how climate warming influences the growth of herbaceous plants, particularly in semi-arid sites. This contrasts with widely reported tree growth decline and even mortality in response to severe water deficits due to climate warming around the world. Here, we use the relatively novel approach of herb-chronology to analyze the correlation between climatic factors and annual ring width in the root xylem of two perennial forb species (Medicago sativa, Potentilla chinensis) in the Loess Plateau of China. We show that warming-induced water deficit has a significant negative effect on the growth of herbaceous plants in the Loess Plateau. Our results indicate that the growth of forbs responds rapidly and sensitively to drought variability, implying that water availability plays a dominant role in regulating the growth of herbaceous plants in semi-arid areas. If warming and drying in the Loess Plateau continue in the future, further affects the growth of herbaceous plants, potentially driving regional changes in the relationship between herbaceous vegetation and climate.


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    Bosco Kidake Kisambo


    Full Text Available Leaf Area Index (LAI dynamics and aboveground biomass of a semi-arid grassland region in Southern Ethiopia were determined over a long rain season. The vegetation was categorized into four distinct vegetation types namely Grassland (G, Tree-Grassland (TG, Bushed-Grassland (BG and Bush-Tree grassland (BT. LAI was measured using a Plant Canopy Analyzer (LAI2000. Biomass dynamics of litter and herbaceous components were determined through clipping while the above ground biomass of trees and shrubs were estimated using species-specific allometric equations from literature. LAI showed a seasonal increase over the season with the maximum recorded in the BG vegetation (2.52. Total aboveground biomass for the different vegetation types ranged from 0.61 ton C/ha in areas where trees were non-existent to 8.80 ± 3.81ton C/ha in the Tree-Grassland vegetation in the study site. A correlation of LAI and AGB yielded a positive relationship with an R2 value of 0.55. The results demonstrate the importance of tropical semi-arid grasslands as carbon sinks hence their potential in mitigation of climate change.

  4. Roots of forbs sense climate fluctuations in the semi-arid Loess Plateau: Herb-chronology based analysis (United States)

    Shi, S.


    Growth of herbaceous plants responds sensitively and rapidly to climate variability. Yet, little is known regarding how climate warming influences the growth of herbaceous plants, particularly in semi-arid sites. This contrasts with widely reported tree growth decline and even mortality in response to severe water deficits due to climate warming around the world. Here, we use the relatively novel approach of herb-chronology to analyze the correlation between climatic factors and annual ring width in the root xylem of two perennial forb species (Medicago sativa, Potentilla chinensis) in the Loess Plateau of China. We show that warming-induced water deficit has a significant negative effect on the growth of herbaceous plants in the Loess Plateau. Our results indicate that the growth of forbs responds rapidly and sensitively to drought variability, implying that water availability plays a dominant role in regulating the growth of herbaceous plants in semi-arid areas. If warming and drying in the Loess Plateau continue in the future, further affects the growth of herbaceous plants, potentially driving regional changes in the relationship between herbaceous vegetation and climate.

  5. Photosynthetic capacity and water use efficiency in Ricinus communis (L. under drought stress in semi-humid and semi-arid areas

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    Full Text Available ABSTRACT Castor bean is one of the crops with potential to provide raw material for production of oils for biodiesel. This species possess adaptive mechanisms for maintaining the water status when subjected to drought stress. A better understanding these mechanisms under field conditions can unravel the survival strategies used by this species. This study aimed to compare the physiological adaptations of Ricinus communis (L. in two regions with different climates, the semi-arid and semi-humid subject to water stress. The plants showed greater vapor pressure deficit during the driest hours of the day, which contributed to higher values of the leaf temperature and leaf transpiration, however, the VPD(leaf-air had the greatest effect on plants in the semi-arid region. In both regions, between 12:00 p.m. and 2:00 p.m., the plants presented reduction in the rates of photosynthesis and intracellular CO2 concentration in response to stomatal closure. During the dry season in the semi-arid region, photoinhibition occurred in the leaves of castor bean between 12:00 p.m. and 2:00 p.m. These results suggest that castor bean plants possess compensatory mechanisms for drought tolerance, such as: higher stomatal control and maintenance of photosynthetic capacity, allowing the plant to survive well in soil with low water availability.

  6. Carbon storage capacity of semi-arid grassland soils and sequestration potentials in northern China. (United States)

    Wiesmeier, Martin; Munro, Sam; Barthold, Frauke; Steffens, Markus; Schad, Peter; Kögel-Knabner, Ingrid


    Organic carbon (OC) sequestration in degraded semi-arid environments by improved soil management is assumed to contribute substantially to climate change mitigation. However, information about the soil organic carbon (SOC) sequestration potential in steppe soils and their current saturation status remains unknown. In this study, we estimated the OC storage capacity of semi-arid grassland soils on the basis of remote, natural steppe fragments in northern China. Based on the maximum OC saturation of silt and clay particles semi-arid environments induced by intensive land use is largely irreversible. Observed SOC increases after improved land management mainly result in an accumulation of labile SOC prone to land use/climate changes and therefore cannot be regarded as contribution to long-term OC sequestration. © 2015 John Wiley & Sons Ltd.

  7. Season-ahead streamflow forecast informed tax strategies for semi-arid water rights markets (United States)

    Delorit, J. D.; Block, P. J.


    In many semi-arid regions multisectoral demands stress available water supplies. The Elqui River valley of north central Chile, which draws on limited capacity reservoirs supplied largely by annually variable snowmelt, is one of these cases. This variability forces water managers to develop demand-based allocation strategies which have typically resulted in water right volume reductions, applied equally per right. Compounding this issue is often deferred or delayed infrastructure investments, which has been linked Chile's Coasian approach to water markets, under which rights holders do not pay direct procurement costs, non-use fees, nor taxes. Here we build upon our previous research using forecasts of likely water rights reductions, informed by season-ahead prediction models of October-January (austral growing season) streamflow, to construct annual, forecast-sensitive, per right tax. We believe this tax, to be borne by right holders, will improve the beneficial use of water resources by stimulating water rights trading and improving system efficiency by generating funds for infrastructure investment, thereby reducing free-ridership and conflict between rights holders. Research outputs will include sectoral per right tax assessments, tax revenue generation, Elqui River valley economic output, and water rights trading activity.

  8. Adaptation to drought in arid and semi-arid environments: Case of the Zambezi Valley, Zimbabwe

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    Emmanuel Mavhura


    Full Text Available Small-scale rain-fed agriculture is the main livelihood in arid to semi-arid regions of subSaharan Africa. The area is characterised by erratic rainfall and frequent droughts, making the capacity for coping with temporal water shortages essential for smallholder farmers. Focusing on the Zambezi Valley, Zimbabwe, this study investigates the impact of drought on food security and the strategies used by smallholder farmers to cope with drought. We used meteorological data and interviews to examine the rainfall variability in the study area and the drought-coping mechanisms employed by smallholder famers respectively. The results show that there are various strategies used by smallholder farmers to cope with the impact of drought. These strategies include drought-tolerant crop production, crop variety diversification, purchasing cereals through asset sales, non-governmental organisations’ food aid and gathering wild fruit. However, consecutive droughts have resulted in high food insecurity and depletion of household assets during droughts. Smallholder farmers in the valley have also resorted to a number of measures taken before, during and after the drought. Still, these strategies are not robust enough to cope with this uncertainty

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

    Energy Technology Data Exchange (ETDEWEB)

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


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

  10. Groundwater recharge estimation under semi arid climate: Case of Northern Gafsa watershed, Tunisia (United States)

    Melki, Achraf; Abdollahi, Khodayar; Fatahi, Rouhallah; Abida, Habib


    Natural groundwater recharge under semi arid climate, like rainfall, is subjected to large variations in both time and space and is therefore very difficult to predict. Nevertheless, in order to set up any strategy for water resources management in such regions, understanding the groundwater recharge variability is essential. This work is interested in examining the impact of rainfall on the aquifer system recharge in the Northern Gafsa Plain in Tunisia. The study is composed of two main parts. The first is interested in the analysis of rainfall spatial and temporal variability in the study basin while the second is devoted to the simulation of groundwater recharge. Rainfall analysis was performed based on annual precipitation data recorded in 6 rainfall stations over a period of 56 years (1960-2015). Potential evapotranspiration data were also collected from 1960 to 2011 (52 years). The hydrologic distributed model WetSpass was used for the estimation of groundwater recharge. Model calibration was performed based on an assessment of the agreement between the sum of recharge and runoff values estimated by the WetSpass hydrological model and those obtained by the climatic method. This latter is based on the difference calculated between rainfall and potential evapotranspiration recorded at each rainy day. Groundwater recharge estimation, on monthly scale, showed that average annual precipitation (183.3 mm/year) was partitioned to 5, 15.3, 36.8, and 42.8% for interception, runoff, actual evapotranspiration and recharge respectively.

  11. Effects of stubble and mulching on soil erosion by wind in semi-arid China (United States)

    Cong, Peifei; Yin, Guanghua; Gu, Jian


    Soil erosion is a growing challenge for agricultural production in Northern China. To explore the effect of variation in stubble height and mulching biomass on soil erosion caused by wind, we conducted a field experiment using a quadratic rotation combination design. Results showed that the quantity of straw mulch was the dominant factor affecting soil erosion, and stubble height was of secondary importance. The soil water content in stubble and straw mulching treatments was higher than in a control treatment at 0-20 cm soil, and the tendency in the amount of soil water content was opposite to the amount of wind erosion (r = -0.882, n = 10, p soil water content observed in the stubble and mulch treatments at the 15-20 cm depth was higher than the change from 0-5 cm to 5-10 cm. Combined, the influence of a stubble height of 34 cm and mulch quantity of 4260 kg·ha-1 lowered the amount of erosion to 0.42 t·ha-1, and increased the corn yield to 11900 kg·ha-1. We determined that those were the most appropriate levels of stubble height and straw mulch for crop fields in the semi-arid regions of Northern China.

  12. Manejo de colheita e espaçamento da palma-forrageira, em consórcio com sorgo granífero, no Agreste de Pernambuco Harvest managing and plant spacing of spinelles fodder cactus, under grain sorghum intercropping at the semi-arid region of Pernambuco State, Brazil

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    Full Text Available Este trabalho foi realizado na zona semi-árida de Pernambuco e teve como objetivo investigar o efeito de espaçamento, e a freqüência e intensidade de colheitas da palma-forrageira (Opuntia ficus-indica Mill. consorciada com sorgo granífero (Sorghum bicolor (L. Moench. O delineamento experimental foi o de blocos ao acaso em parcelas subdivididas, sendo os espaçamentos alocados nas parcelas principais, e as freqüências e intensidades de colheitas, nas subparcelas. Os resultados são de um período de 12 anos, e as produções de matéria seca de palma, de grãos e restolhos de sorgo foram: 5,23, 1,65 e 2,07; 4,51, 1,30 e 2,10; 2,75, 1,97 e 3,51 t/ha/ano, em espaçamentos de 2,0 m x 1,0 m; 3,0 m x 1,0 m x 0,50 m e 7,0 m x 1,0 m x 0,50 m, respectivamente. A produção de matéria seca foi diferente entre as freqüências de corte, quando foram conservados os artículos primários: 4,08 t/ha/ano na freqüência de quatro anos, e de 3,43 t/ha/ano na freqüência de dois anos. A produção de palma aumentou com o período de crescimento da planta, nas duas intensidades de corte estudadas. A composição química dos artículos de palma e dos restolhos de sorgo foi pouco afetada pelos tratamentos.This trial was carried out in the semi-arid region of Pernambuco, aiming to study plant spacing and harvest frequencies and intensities of forage cactus (Opuntia ficus-indica Mill.. An experimental design in a split plot design was applied, in which plant spacing were used as the main plots and harvest frequencies and intensities as the subplots. Results presented in this work are related to a twelve-year period. The dry matter yields of forage cactus, sorghum grains and stover were: 5.23, 1.65 and 2.07; 4.51, 1.30 and 2.10; 2.75, 1.97 and 3.5 ton/ha/year, for plant spacing 2.0 m x 1.0 m; 3.0 m x 1.0 m x 0.50 m and 7.0 m x 1.0 m x 0.50 m, respectively. Dry matter yield was different between harvest frequencies, when primary articles were conserved: 4

  13. Comunidade microbiana e mesofauna edáficas em solo sob caatinga no semi-árido da Paraíba Soil microbial community and mesofauna under dry forest vegetation in the semi-arid region of Paraíba, Brazil

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    Patrícia Carneiro Souto


    Full Text Available A atividade biológica do solo é responsável por inúmeras transformações físicas e químicas dos resíduos orgânicos que são depositados, mantendo, assim, a sustentabilidade do ambiente. O presente estudo objetivou avaliar a distribuição da comunidade microbiana e da mesofauna edáfica no semi-árido da Paraíba. Para determinação da população de microrganismos, foram coletadas amostras de solo na profundidade de 0-15 cm. A contagem total de fungos e de bactérias foi realizada em meios de cultura específicos. A extração da mesofauna foi feita pelo método de Berlese-Tullgren modificado. Oscilações no conteúdo de água do solo e na temperatura promoveram variações na população microbiana. A população de fungos foi superior à de bactérias nos dois anos de observação, provavelmente devido ao pH do solo da área de estudo, que é ligeiramente ácido. O índice de diversidade de Shannon (H e o de Pielou (e variaram de acordo com a época de coleta. Os grupos mais freqüentes da mesofauna do solo foram Diptera (42,5 %, Acarinae (40,3 % e Collembola (8,8 %, indicando que esses organismos possuem papel importante na ciclagem de nutrientes em área de Caatinga.The biological soil activity is responsible for several physical and chemical transformations of deposited organic residues, therefore maintaining the environmental sustainability. The aim of this study was to evaluate the distribution of the soil microbial community and mesofauna in a dry forest (Caatinga in the semi-arid region of Paraíba, northeastern Brazil. To determine the microorganism population soil samples from the 0-15 cm soil layer were evaluated. Total counts of fungi and bacteria were evaluated in specific culture media. The Berleusse-Tüllgren modified method was used to extract the soil mesofauna. Oscillations in the soil water content and high temperatures promoted variations in the microbial population. The fungi population was larger than that of

  14. Simulation of spectral bands of the MERIS sensor to estimate chlorophyll-a concentrations in a reservoir of the semi-arid region = Simulação de bandas espectrais do sensor MERIS para estimativas das concentrações de clorofila-a em reservatório da região semiárida

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    Fernando Bezerra Lopes


    Full Text Available Nowadays, the monitoring of water is essential for the sustainability and better management of water resources. The use of remote sensing data is important, since it allows evaluation of dynamic problems in aquatic systems, such as the eutrophication of bodies of water and suspended sediment. The aim of this study was to estimate chlorophyll-a concentrations in a reservoir of the semi-arid region of Brazil using simulated orbital-sensor data, as an aid in the management of water resources. The study area corresponded to the Orós reservoir, in the State of Ceará, Brazil. Water samples for analysis of the chlorophyll-a and measurements of the spectral radiance of the aquatic system were collected from 20 points. The radiance was measured by spectroradiometer. The data were collected in June and August of 2011. The model using three bands of the MERIS sensor (7, 9 and 10 presented an R2 of 0.84. For the two-band model (7 and 9, the value of R2 was 0.85. The waters of the Orós reservoir were all classified as eutrophic. The main optically active component in modelling the shape of the spectra was chlorophyll-a. The models showed a mean absolute error (MAE of 3.45 and 3.61 μg L-1 for the three- and two-band models respectively. The models displayed high coefficients of determination, i.e. the simulations show the feasibility of estimating chlorophyll-a concentration from the data of the MERIS orbital sensor. = O monitoramento da água nos dias atuais é essencial para a sustentabilidade e para a melhor gestão dos recursos hídricos. O uso de dados de sensoriamento remoto é relevante, uma vez que permite a avaliação de problemas dinâmicos em sistemas aquáticos, tais como a eutrofização de corpos de água e dos sedimentos em suspensão. Objetivou-se estimar as concentrações de clorofila-a em reservatório da região semiárida do Brasil, usando dados simulados de sensor orbital, como suporte à gestão dos recursos hídricos. A área de

  15. Perfil microbiológico, celular e fatores de risco associados à mastite subclínica em cabras no semiárido da Paraíba Cellular and microbiological profiles and risk factors for subclinical mastitis in goats in the semi-arid region of Paraíba

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    Patrícia B. Neves


    Full Text Available Foi realizado um estudo da mastite subclínica em nove rebanhos de cabras leiteiras no semiárido paraibano com o objetivo de determinar a ocorrência da infecção, avaliar o perfil microbiológico e celular do leite, testar a sensibilidade dos microorganismos isolados frente a antimicrobianos além de identificar os fatores de risco. Foram utilizadas 131 cabras leiteiras das quais foram colhidas 261 amostras de leite para exame microbiológico e 131 para contagem de células somáticas (CCS. Na ocasião das colheitas foi realizado o California Mastitis Test (CMT e aplicado um questionário epidemiológico por propriedade. Houve crescimento bacteriano em 30 amostras (11,49% com 25 (83,33% dos isolados identificados como Staphylococcus coagulase negativa e cinco (16,66% Staphylococcus aureus. A média de CCS foi de 1,39x10(6 células/ml. O CMT apresentou baixa sensibilidade (46,7% e baixa especificidade (60,6% quando comparado ao exame microbiológico. A gentamicina e a associação da neomicina, bacitracina e tetraciclina foram os antimicrobianos contra os quais os microrganismos isolados apresentaram 100% de sensibilidade. Penicilina e ampicilina foram os de maiores índices de resistência (66,67% e 63,89%, respectivamente. A caprinocultura não ser a atividade principal da propriedade e o não isolamento de animais doentes, foram identificados como fatores de risco para a mastite subclínica caprina nas propriedades estudadas. Programas de controle e profilaxia da mastite devem ser implementados enfocando as medidas de higiene na ordenha e correção dos fatores de risco identificados nesse estudo.A subclinical mastitis study was conducted in nine dairy goat herds in the semi-arid region of Paraíba state, Northeastern Brazil, to determine the occurrence of infection, to evaluate microbiological and cellular profiles of the milk, to test the sensitivity of isolated microorganisms to antimicrobials, and to identify risk factors. One hundred

  16. Análise espaço-temporal do uso da terra em parte do semi-árido cearense Spatial and temporal-time analysis of land use in part of the semi-arid region of Ceará State, Brazil

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    J. B. Andrade


    Full Text Available A cobertura vegetal exerce papel imprescindível à proteção e conservação dos recursos naturais, principalmente no que diz respeito aos solos. Este estudo teve como objetivo avaliar e analisar a dimensão espacial e temporal da ação antrópica na cobertura vegetal de parte do semi-árido cearense, utilizando imagens LANDSAT TM-5, de 1985 e 1994, e técnicas de geoprocessamento, para verificar a hipótese de que a degradação ambiental vem sendo intensificada. Foram confeccionadas cartas de vegetação, uso da terra, solos e hidrografia, obtendo-se cartas de sobreposição, por meio das quais se constatou o aumento de áreas degradadas nas diferentes unidades fitoecológicas. No período de uma década, comprovou-se o processo progressivo da degradação nas áreas dos municípios de Independência, Pedra Branca, Mombaça e Tauá, tendo as áreas do município de Pedra Branca apresentado menor degradação. A unidade fitoecológica mais degradada, dentre as estudadas, foi a Caatinga Arbórea Aberta, desencadeando processos de degradação e transformação das unidades circunvizinhas. Grande parte da área foi atingida por processos de degradação ambiental, com forte pauperização da biodiversidade, acompanhados por um rebaixamento geral das formações vegetais.The vegetation cover plays a key role in protection and conservation of natural resources, particularly concerning soils. This study had as objective to analyze space and time dimensions of anthropic influence on the vegetation cover in part of the semi-arid region of the Ceará State, Brazil. LANDSAT TM-5 satellite images of 1985 and 1994 combined with geoprocessing techniques were used to verify the hypothesis of intensification of environmental degradation. Maps of the vegetation cover, land use, soils, and hydrography were elaborated. They pointed out to an increase in degraded areas of the different phytoecological units. During this decade, a progressive degradation

  17. Great Basin semi-arid woodland dynamics during the late quaternary

    Energy Technology Data Exchange (ETDEWEB)

    Wigand, P.E.; Hemphill, M.L.; Sharpe, S.E. [Univ. and Community College System of Nevada, Reno, NV (United States)] [and others


    Semi-arid woodlands have dominated the middle elevations of Great Basin mountain ranges during the Holocene where subalpine woodlands prevailed during the Pleistocene. Ancient woodrat middens, and in a few cases pollen records indicate in the late Pleistocene and early Holocene woodland history lowered elevation of subalpine woodland species. After a middle Holocene retrenchment at elevations in excess of 500 meters above today, Juniper-dominated semi-arid woodland reached its late Holocene maximum areal extent during the Neoglacial (2 to 4 ka). These records, along with others indicate contracting semi-arid woodland after the Neoglacial about 1.9 ka. Desert shrub community expansion coupled with increased precariousness of wetland areas in the southern Great Basin between 1.9 and 1.5 ka coincide with shrinking wet-lands in the west-central and northern Great Basin. Coincident greater grass abundance in northern Great Basin sagebrush steppe, reaching its maximum between 1.5 and 1.2 ka, corresponds to dramatic increases in bison remains in the archaeological sites of the northern Intermontane West. Pollen and woodrat midden records indicate that this drought ended about 1.5 ka. Succeeding ameliorating conditions resulted in the sudden northward and downward expansion of pinon into areas that had been dominated by juniper during the Neoglacial. Maximum areal extent of pinon dominated semi-arid woodland in west-central Nevada was centered at 1.2 ka. This followed by 100 years the shift in dominance from juniper to pinon in southern Nevada semi-arid woodlands. Great Basin woodlands suffered from renewed severe droughts between .5 to .6 ka. Effectively wetter conditions during the {open_quotes}Little Ice Age{close_quotes} resulted in re-expansion of semi-arid woodland. Activities related to European settlement in the Great Basin have modified prehistoric factors or imposed new ones that are affecting woodland response to climate.

  18. Use of Satellite SAR for Understanding Long-Term Human Occupation Dynamics in the Monsoonal Semi-Arid Plains of North Gujarat, India

    Directory of Open Access Journals (Sweden)

    Francesc C. Conesa


    Full Text Available This work explores the spatial distribution of monsoonal flooded areas using ENVISAT C-band Advanced Synthetic Aperture Radar (ASAR in the semi-arid region of N. Gujarat, India. The amplitude component of SAR Single Look Complex (SLC images has been used to estimate the extent of surface and near-surface water dynamics using the mean amplitude (MA of monsoonal (July to September and post-monsoonal (October to January seasons. The integration of SAR-derived maps (seasonal flooding maps and seasonal MA change with archaeological data has provided new insights to understand present-day landscape dynamics affecting archaeological preservation and visibility. Furthermore, preliminary results suggest a good correlation between Mid-Holocene settlement patterns and the distribution and extension of seasonal floodable areas within river basin areas, opening interesting inroads to study settlement distribution and resource availability in past socio-ecological systems in semi-arid areas.

  19. Initial hydrological modelling to assess impacts of different land uses on process hydrology in a small-scale semi-arid catchment in the Western Cape Province, South Africa

    CSIR Research Space (South Africa)

    Steudel, T


    Full Text Available shown that hydrological process dynamics are strongly influenced by the given land use practice. Since semi-arid regions suffer from water scarcity, an optimized land use practice is important for sustainable management of limited water resources...) Refe renc e Initial hydrological modelling to assess impacts of different land uses on process hydrology in a small-scale semi-arid catchment in the Western Cape Province, South Africa Thomas Steudel1, Willem De Clercq2, Richard Bugan2,3, Nebo...

  20. Floristic similarity and dispersal syndromes in a rocky outcrop in semi-arid Northeastern Brazil. (United States)

    Costa, Elainne Cristina Silva; Lopes, Sérgio de Faria; Melo, José Iranildo Miranda de


    Floristic studies provide valuable information on species richness in a region, and are particularly important if these areas belong to less studied environments, such as rocky outcrops, that may increase our knowledge. An important aspect for species colonization includes the mechanisms of diaspores dispersal in each community; these are essential to understand its structure, dynamics, and the regeneration process, and constitute an important tool for conservation. We developed a floristic survey on a granite-gneiss outcrop with the objective to increase the knowledge on plant diversity, through a floristic similarity analysis and detection of dispersal syndromes of sampled species, in a semi-arid region of Brazil. The fieldwork included collection and observation of the botanical material in loco during a period of 12 months. A total of 161 species belonging to 127 genera and 50 families of angiosperms were recorded. Fabaceae, Asteraceae and Convolvulaceae were the most representative families in number of species. Allophylus quercifolius (Mart.) Radlk. (Capparaceae) and Lafoensia pacari A. St.-Hil. (Lythraceae) represented new records for the State of Paraiba. The autochoric syndrome was the most representative, with 51.5 % of the recorded species; the anemochory was the second most representative syndrome with 26.7 % of the species; and finally the zoochory, representing 22.3 % of the species. The floristic similarity dendrogram showed the formation of three well-defined groups, whose area with the highest value (J = 33.2) is located in a Caatinga region called Cariri Paraibano, while the lowest value observed (J = 5.2), occurred in a settled area in two geomorphological units, a crystalline complex and a plateau region. These results may be due to the varying topographic conditions and edaphic heterogeneity arising from the specific geological formation of the region. These results yet demonstrate that, in rocky outcrops, abiotic syndromes represent an

  1. Floristic similarity and dispersal syndromes in a rocky outcrop in semi-arid Northeastern Brazil

    Directory of Open Access Journals (Sweden)

    Elainne Cristina Silva Costa


    Full Text Available Floristic studies provide valuable information on species richness in a region, and are particularly important if these areas belong to less studied environments, such as rocky outcrops, that may increase our knowledge. An important aspect for species colonization includes the mechanisms of diaspores dispersal in each community; these are essential to understand its structure, dynamics, and the regeneration process, and constitute an important tool for conservation. We developed a floristic survey on a granite-gneiss outcrop with the objective to increase the knowledge on plant diversity, through a floristic similarity analysis and detection of dispersal syndromes of sampled species, in a semi-arid region of Brazil. The fieldwork included collection and observation of the botanical material in locoduring a period of 12 months. A total of 161 species belonging to 127 genera and 50 families of angiosperms were recorded. Fabaceae, Asteraceae and Convolvulaceae were the most representative families in number of species. Allophylus quercifolius(Mart. Radlk. (Capparaceae and Lafoensia pacariA. St.-Hil. (Lythraceae represented new records for the State of Paraiba. The autochoric syndrome was the most representative, with 51.5 % of the recorded species; the anemochory was the second most representative syndrome with 26.7 % of the species; and finally the zoochory, representing 22.3 % of the species. The floristic similarity dendrogram showed the formation of three well-defined groups, whose area with the highest value (J = 33.2 is located in a Caatinga region called Cariri Paraibano, while the lowest value observed (J = 5.2, occurred in a settled area in two geomorphological units, a crystalline complex and a plateau region. These results may be due to the varying topographic conditions and edaphic heterogeneity arising from the specific geological formation of the region. These results yet demonstrate that, in rocky outcrops, abiotic syndromes

  2. Land use change and carbon cycle in arid and semi-arid lands of East and Central Asia

    Energy Technology Data Exchange (ETDEWEB)

    Togtohyn Chuluun; Dennis Ojima [Colorado State University, Fort Collins, CO (USA). Natural Resource Ecology Laboratory


    Dramatic changes in land use have occurred in arid and semi-arid lands of Asia during the 20th century. Grassland conversion into croplands and ecosystem degradation is widespread due to the high growth rate of human population and political reforms of pastoral systems. Rangeland degradation made many parts of this region vulnerable to environmental and political changes. The collapse of the livestock sector in some states of central Asia, expansion of livestock in China and intensive degradation of grasslands in China are examples of the responses of pastoral systems to these changes over the past decades. Carbon dynamics in this region is highly variable in space and time. Land use/cover changes with widespread reduction of forest and grasslands increased carbon emission from the region.

  3. The effects of clouds and aerosols on net ecosystem CO2 exchange over semi-arid Loess Plateau of Northwest China

    Directory of Open Access Journals (Sweden)

    T. Wang


    Full Text Available The impacts of clouds and atmospheric aerosols on the terrestrial carbon cycle at semi-arid Loess Plateau in Northwest China are investigated, by using the observation data obtained at the SACOL (Semi-Arid Climate and Environment Observatory of Lanzhou University site. Daytime (solar elevation angles of larger than 50° net ecosystem exchange (NEE of CO2 obtained during the midgrowing season (July–August are analyzed with respect to variations in the diffuse radiation, cloud cover and aerosol optical depth (AOD. Results show a significant impact by clouds on the CO2 uptake by the grassland (with smaller LAI values located in a semi-arid region, quite different from areas covered by forests and crops. The light saturation levels in the canopy are low, with a value of about 434.8 W m−2. Thus, under overcast conditions of optically thick clouds, the CO2 uptake increases with increasing clearness index (the ratio of global solar radiation received at the Earth surface to the extraterrestrial irradiance at a plane parallel to the Earth surface, and a maximum CO2 uptake and light use efficiency of vegetation occur with the clearness index of about 0.37 and lower air temperature. Under other sky conditions, CO2 uptake decreases with cloudiness but light use efficiency is enhanced, due to increased diffuse fraction of PAR. Additionally, under cloudy conditions, changes in the NEE of CO2 also result from the interactions of many environmental factors, especially the air temperature. In contrast to its response to changes in solar radiation, the carbon uptake shows a slightly negative response to increased AOD. The reason for the difference in the response of the semi-arid grassland from that of the forest and crop lands may be due to the difference in the canopy's architectural structure.

  4. A Bayesian geostatistical estimation of biomass in semi-arid rangelands by combining airborne and terrestrial laser scanning data (United States)

    Li, A.; Glenn, N. F.


    Biomass of vegetation is critical for carbon cycle research. Estimating biomass from field survey data is laborious and/or destructive and thus retrieving biomass from remote sensing data may be advantageous. Most remote sensing biomass studies have focused on forest ecosystems, while few have focused on low stature vegetation, such as grasses in semi-arid environments. Biomass estimates for grass are significant for studying wildlife habitat, assessing fuel loads, and studying climate change response in semi-arid regions. Recent research has demonstrated the ability of small footprint airborne laser scanning (ALS) data to extract sagebrush height characteristics and the ability of terrestrial laser scanning (TLS) data to estimate vegetation volume over semi-arid rangelands. ALS has somewhat lower resolution than TLS, but has improved spatial coverage over TLS. Combining ALS and TLS is a powerful tool to estimate biomass on regional scales. Bayesian geostatistics, also known as Bayesian Maximum Entropy (BME), can fuse multiple data sources across scales and provide estimation uncertainties for the integration of ALS and TLS data for grass biomass. Regression models are used to approximately delineate the relationship between field biomass measurements and TLS derived height and shape metrics. We then consider TLS plot-level data at the point scale with ALS data at the area scale. The regularization method is utilized to establish the scaling relations between TLS-derived and ALS-derived metrics. The metric maps from the ALS level are reconstructed using a BME method based on regularized variograms. We gain biomass and estimation uncertainty on the regional scale by introducing updated metrics into the model. In order to evaluate the effectiveness of the BME method, we develop simple independent regression models by assuming the TLS-derived metrics as ground reference data. Therefore, the regression model is used to correct the ALS-estimated values and we retrieve

  5. Manure and inorganic N affect trace gas emissions under semi-arid irrigated corn (United States)

    Dairy manure is often applied to cropped soils as a substitute for inorganic N fertilizers, but the impacts of manure on soil greenhouse gas (GHG) fluxes, yields and soil N are uncertain in the semi-arid western U.S. Soil carbon dioxide (CO2-C), methane (CH4-C), and nitrous oxide (N2O-N) emissions ...

  6. Effects of 22 years of re-vegetation on soil quality in the semi-arid ...

    African Journals Online (AJOL)



    Dec 15, 2009 ... China. One-fifth of this area is occupied by semi-arid are as, which are primarily located around the Loess Plateau. (62.4 × 104 km2). The Loess Plateau is located in the north and the ... forests or grasslands known as the grain for green pro- ... tory where plant litter, coarse root materials and stones were re-.

  7. The quantification of rangeland condition in a semi-arid grassland of ...

    African Journals Online (AJOL)

    The degradation gradient technique was used to quantify rangeland .condition in areas ranging from poor, trampled areas close to watering points to well managed areas in a semi-arid. sweet grassland of southern Africa. Ecological values were linked to species by means of their individual positions on the degradation ...

  8. Conservation tillage systems and water productivity implications for smallholder farmers in semi-arid Ethiopia

    NARCIS (Netherlands)

    Temesgen, M.L.


    Conservation tillage systems have been adopted by farmers in many countries to solve the problem of land degradation and declining water productivity. However, direct application of such tillage systems was not possible among resource poor smallholder farmers in semi arid areas of Ethiopia. Problems

  9. Tillage and farmyard manure efects on crusting and compacting soils at Katumani, Semi-arid Kenya

    NARCIS (Netherlands)

    Biamah, E.K.; Sterk, G.; Stroosnijder, L.


    In semi-arid Kenya, the most dominatn soil types are of limited agricultural productivity due to crusting and compaction. The occurence of soil crusting and compaction is attributed to seasonal rainfall characteristics, physical soil properties and bad tillage practices. Soil crusting and compaction

  10. Runoff controlling factors in various sized catchments in a semi-arid Mediterranean environment in Spain

    NARCIS (Netherlands)

    Wit, A.M.W. de


    Understanding land degradation in a semi-arid Mediterranean environment is very difficult because of the contributing factors: precipitation, infiltration vegetation cover and discontinuity of flow and the temporal and spatial levels of resolution at which these factors are acting. Therefore it

  11. The Soil-Land use System in a Sand Spit Area in the Semi-Arid ...

    African Journals Online (AJOL)

    The development and sustainability of a horticultural system at the Keta sand spit in south-eastern Ghana is described and discussed. The main crop is shallot grown on pure sandy soils in a semi-arid climate. It is a cash crop system highly dependent on a substantial input of manure and irrigation water from a shallow ...

  12. Hydrologic Connectivity: a Framework to Understand Threshold Behaviour in Semi-Arid Landscapes. (United States)

    Saco, Patricia; Rodriguez, Jose; Keesstra, Saskia; Moreno-de las Heras, Mariano; Sandi, Steven; Baartman, Jantiene; Cerdà, Artemi


    Anthropogenic activities and climate change are imposing an unprecedented pressure on arid and semi-arid ecosystems, where shortage of water can trigger shifts in landscapes' structures and function leading to degradation and desertification. Hydrological connectivity is a useful framework for understanding water redistribution and scaling issues associated to runoff and sediment production, since human and/or natural disturbances alter the surface water availability and pathways increasing/decreasing connectivity. In this presentation, we illustrate the use of the connectivity framework for several examples of dryland systems that are analysed at a variety of spatial and temporal scales. In doing so, we draw particular attention to the analysis of co-evolution of system structures and function, and how they drive threshold behaviour leading to desertification and degradation. We first analyse the case of semi-arid rangelands, where feedbacks between decline in vegetation density and landscape erosion reinforces degradation processes driven by changes in connectivity until a threshold is crossed above which the return to a functional system is unlikely. We then focus on semi-arid wetlands, where decreases in water volumes promotes dryland vegetation encroachment that changes drainage conditions and connectivity potentially reinforcing redistribution of flow paths to other wetland areas. The examples presented highlight the need to incorporate a co-evolutionary framework for the analysis of changing connectivity patterns and the emergence of thresholds in arid and semi-arid systems.

  13. The challenges of rehabilitating denuded patches of a semi-arid ...

    African Journals Online (AJOL)

    The challenges of rehabilitating denuded patches of a semi-arid environment in Kenya. ... In Kenya, grass reseeding technology has been used to combat land degradation. However ... A questionnaire was administered to capture farmer perceptions on failures on rangeland rehabilitation using grass reseeding technology.

  14. Comparison of groundwater recharge estimation methods for the semi-arid Nyamandhlovu area, Zimbabwe

    NARCIS (Netherlands)

    Sibanda, T.; Nonner, J.C.; Uhlenbrook, S.


    The Nyamandhlovu aquifer is the main water resource in the semi-arid Umguza district in Matebeleland North Province in Zimbabwe. The rapid increase in water demand in the city of Bulawayo has prompted the need to quantify the available groundwater resources for sustainable utilization. Groundwater

  15. Spatiotemporal soil and saprolite moisture dynamics across a semi-arid woody plant gradient (United States)

    Woody plant cover has increased 10-fold over the last 140+ years in many parts of the semi-arid western USA. Woody plant cover can alter the timing and amount of plant available moisture in the soil and saprolite. To assess spatiotemporal subsurface moisture dynamics over two water years in a snow-d...

  16. Assessment of Reservoir Storage in a Semi-Arid Environment Using ...

    African Journals Online (AJOL)

    Assessment of Reservoir Storage in a Semi-Arid Environment Using Gould Probability Matrix. ... a helpful Frequently Asked Questions about PDFs. Alternatively, you can download the PDF file directly to your computer, from where it can be opened using a PDF reader. To download the PDF, click the Download link above.

  17. Winter grazing decreases wildfire risk, severity, and behavior in semi-arid sagebrush rangelands (United States)

    Wildfires are an ecological and economic risk for many semi-arid rangelands which has resulted in increased pressure for pre-suppression management of fuels. In rangelands, fuel management treatment options are limited by costs. We evaluated winter grazing as a tool to manage fuels and alter fire ...

  18. Determining soil erosion rates on semi-arid watersheds using radioisotope-derived sedimentation chronology 2327 (United States)

    This study investigates erosion dynamics of the past 90 years on three small semi-arid watersheds with histories of grazing and vegetation change. Activity of 137Cs and excess 210Pb from 18 cores collected from sedimentation ponds were measured using a gamma spectrometer. The sediment was dated usi...

  19. Soil and water conservation in semi-arid areas of Tanzania: national ...

    African Journals Online (AJOL)

    ... farmers have directed their efforts to the effective management of rainwater for the production of high water-demanding but high-value crops such as rice and vegetables. It is proposed that sustainable adoption of soil and water conservation practices in semi-arid areas of Tanzania requires policies and strategies that: (i) ...

  20. Catchment management in semi-arid area of central South Africa ...

    African Journals Online (AJOL)

    This accentuates the need for wise decisions by catchment management agencies (CMAs), especially in water-scarce semi-arid areas. These decisions become more and more complex as the range of demands widens over the spectrum of water consumers, i.e. municipal, industrial, irrigation and rain-fed farming. A study ...

  1. The challenges of rehabilitating denuded patches of a semi-arid ...

    African Journals Online (AJOL)


    scalarum, Eragrostis curvula, Datura stramonium, Tridax procumbens, Barleria taitensis and. Commelina bengalensis. Results showed that out of all the men- tioned weeds, only Ipomoea kituensis greatly affected established grass stands. Ipomoea kituensis is a very common and notorious weed in the semi-arid districts of.

  2. Pathways to Resilience in Semi-Arid Economies | CRDI - Centre de ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    How can populations become resilient to climate change while pursuing economic growth? This question is at the heart of a research project designed to support climate-resilient economic development in semi-arid lands. It will do so by addressing the conditions for economic growth and considering the needs of women ...

  3. Vegetation monitoring on semi-arid grasslands unglazed by domestic livestock (United States)

    Linda Kennedy; Dan Robinett


    The Research Ranch is an 8000-acre sanctuary and research facility in the semi-arid grasslands of southeastern Arizona, USA. Cattle were removed from the property in 1968 to provide a reference area by which various land uses, such as grazing and exurbanization, could be evaluated. Vegetation transects were established in 2000 and 2003 on several ecological sites in...

  4. Shah-Kan-Daw: Anthropogenic simplification of semi-arid vegetation structure (United States)

    David A. Charlet


    Semi-arid shrublands and woodlands of Nevada are changing in the face of many daunting challenges. I compare Nevada to Iran to understand these challenges better, because Iran and Nevada have similar climate, geology, physiography, and latitude. Floristically, Iran and Nevada share many dominant genera, and many of Nevada?s troubling invasive species are native to Iran...

  5. Energetics of the green iguana (Iguana iguana) in a semi-arid environment

    NARCIS (Netherlands)

    van Marken Lichtenbelt, Wouter David


    Energy budgets in the herbivorous green iguana (Iguana Iguana) were studied from April 1985-October 1988 in a strongly seasonal environment on the semi-arid island Curacao (Netherlands Antilles) under the auspices of the CARMABI Foundation in cooperation with the State University of Groningen (The

  6. Catchment management in semi-arid area of central South Africa ...

    African Journals Online (AJOL)

    South Africa: Strategy for improving water productivity. YE Woyessa1*, M Hensley2 and LD van ... This accentuates the need for wise decisions by catchment management agencies (CMAs), espe- cially in water-scarce semi-arid .... crop model together with long-term rainfall data it was pos- sible to predict long-term yields of ...

  7. Rainfall-interception-evaporation-runoff relationships in a semi-arid catchment, northern Limpopo basin, Zimbabwe

    NARCIS (Netherlands)

    Love, D.; Uhlenbrook, S.; Corzo Perez, G.; Twomlow, S.; Zaag, van der P.


    Characterizing the response of a catchment to rainfall, in terms of the production of runoff vs the interception, transpiration and evaporation of water, is the first important step in understanding water resource availability in a catchment. This is particularly important in small semi-arid

  8. Farmer perceptions on climate change and variability in semi-arid ...

    African Journals Online (AJOL)

    Farmers in semi-arid Zimbabwe prioritise climate variability as their major agricultural productivity-reducing problem. This paper raises the importance of considering local farmers' perceptions on climate risk, as this greatly influences on-farm investments and decision-making in agricultural management and production in ...

  9. Potential hominin plant foods in northern Tanzania: semi-arid savannas versus savanna chimpanzee sites. (United States)

    Copeland, Sandi R


    Savanna chimpanzees are useful as referential models for early hominins, and here potential differences between chimpanzee and early hominin ecology is the focus. Whereas chimpanzees inhabit only a handful of modern African savannas, there is evidence that early hominins occupied relatively more open and arid savannas than those in which chimpanzees live. In order to help expand potential models of early hominin palaeoecology beyond savanna chimpanzee-like scenarios, and to provide a basis for future modeling and testing of actual hominin diets, this study compares the types of plant foods available in modern semi-arid savannas of northern Tanzania to plant foods at savanna chimpanzee sites. The semi-arid savannas are not occupied by modern chimpanzees, but are potentially similar to environments occupied by some early hominins. Compared to savanna chimpanzee habitats, the northern Tanzania semi-arid savanna has a lower density and fewer species of trees that produce fleshy fruits. Additionally, the most abundant potential hominin plant foods are seasonally available Acacia seeds/pods and flowers, grass seeds, and the underground parts of marsh plants, as evidenced by vegetation surveys and by studies of the diets of baboons that forage in similar areas. The information from this study should be useful for framing hypotheses about hominin diets for sites with palaeoenvironmental contexts similar to those of the northern Tanzania semi-arid savannas and for contextualising tests of actual hominin diets (e.g., those based on dental microwear or isotopes).

  10. Gastrointestinal nematode infections in dorper lambs in a semi-arid ...

    African Journals Online (AJOL)

    INFECTIONS PAR DES NEMATODES GASTRO-INTESTINAUX CHEZ DES AGNEAUX DORPER DANS UNE ZONE SEMI-ARIDE DU DISTRICT DE KAJIADO AU KENYA Résumé On a mené une étude sur la prévalence des infections par les nématodes gastro-intestinaux chez des agneaux Dorper par rapport aux effets de ...

  11. Infiltration and planting pits for improved water management and maize yield in semi-arid Zimbabwe

    NARCIS (Netherlands)

    Nyakudya, I.W.; Stroosnijder, L.; Nyagumbo, I.


    Realising that rainwater harvesting (RWH) improves crop productivity, smallholder farmers in semi-arid Zimbabwe modified contour ridges traditionally used for rainwater management by digging infiltration pits inside contour ridge channels in order to retain more water in crop fields. However,

  12. Contour hedgerows and grass strips in erosion and runoff control in semi-arid Kenya

    NARCIS (Netherlands)

    Kinama, J.M.; Stigter, C.J.; Ong, C.K.; Ng'ang'a, J.K.; Gichuki, F.N.


    Most early alley cropping studies in semi-arid Kenya were on fairly flat land while there is an increase in cultivated sloping land. The effectiveness of aging contour hedgerows and grass strips for erosion control on an about 15% slope of an Alfisol was compared. The five treatments were Senna

  13. Erosion and terrace failure due to agricultural land abandonment in a semi-arid environment

    NARCIS (Netherlands)

    Lesschen, J.P.; Cammeraat, L.H.; Nieman, T.


    Agricultural land abandonment is currently widely spread in Mediterranean countries and a further increase is expected. Previous research has shown that abandoned fields in semi-arid areas are more vulnerable to gully erosion. The absence of ploughing and slow vegetation recovery cause the formation

  14. Fire and the dynamics of a semi-arid grassland: influence on soil ...

    African Journals Online (AJOL)

    The short-term impact of fire burning with the wind (head fire) and against the wind (back fire) on soil characteristics (soil-water content, soil compaction, soil temperature, organic matter, pH, exchangeable Ca, Mg, K, Na and extractable P) were determined in a semi-arid grassland. This study was conducted over two ...

  15. Flood generation and classification of a semi-arid intermittent flow watershed: Evrotas river

    NARCIS (Netherlands)

    Tzoraki, O.; Cooper, D.; Kjeldsen, T.; Froebrich, J.; Querner, E.P.; Gallart, F.; Karalemas, N.


    Hourly water level measurements were used to investigate the flood characteristics of a semi-arid river in Greece, the Evrotas. Flood events are analysed with respect to flood magnitude and occurrence and the performance of Curve Number approach over a period of 2007–2011. A distributed model, Soil

  16. Appropriate technology for sustainable family agriculture in the semi-arid: solar water pumping for located irrigation; Tecnologia apropriada para a agricultura familiar sustentavel do semi-arido brasileiro: bombeamento solar de agua para irrigacao localizada

    Energy Technology Data Exchange (ETDEWEB)

    Costa, Heitor Scalambrini [Universidade Federal de Pernambuco (NAPER/UFPE), Recife, PE (Brazil). Nucleo de Apoio a Projetos de Energias Renovaveis], Email:


    Water and energy are the physic factor, which are most influential on the life conditions in the semi-arid rural environment as a whole and in the agriculture production systems in particular. Water is a resource, which - even though not rare - is found in limited quantities and not always is available on the ground surface, meaning that it should be retrieved through either proper wells or deep holes excavated into ground. Therefore, its use should be optimized. In the rural environment to turn water into an available resource in a sufficient amount in order to improve the population life conditions is still a challenge. In the rural semi-arid regions the electric energy distribution is small compared to the other regions of the country. Nevertheless the geographic position of the Brazilian Northeast - close to the equator - adds to this region high levels of insolation - something close to 3,000 hours of sunshine per year - turning this energy resource into a very abundant one. It is known that the use of solar energy, among the use of other resources, has increased the most worldwide in the last decade. The use of photovoltaic cells has increased around 17% per year in the 90's. In the last years several applications, which had the sun as their electric energy resource, were implemented in the rural areas of many countries. The Brazilian Northeast region was the preferred target of programs and projects aiming at the dissemination of the photovoltaic solar technology. Water pumping is one among the most noble applications of the photovoltaic solar technology. There are many pumping systems configurations for either deep or shallow wells, which use either superficial, immerse or floating motor-pumps, which in turn can be driven by either continuum or alternate current. In this work the usage of water pumped with solar energy from Amazon wells (also called 'cacimboes') for small family-based areas of localized irrigation (less than 1 ha), whose main

  17. Necrophagous beetles associated with carcasses in a semi-arid environment in northeastern Brazil: implications for forensic entomology. (United States)

    Mayer, Ana C G; Vasconcelos, Simão D


    Data on the ecology and bionomics of necrophagous beetles are scarce in tropical countries despite their relevance in forensic investigations. We performed a survey on the diversity and temporal pattern of colonization of beetles on pig carcasses in a fragment of dry forest in northeastern Brazil. We collected 1550 adults of diverse feeding habits from 12 families, of which 96% had necrophagous and/or copro-necrophagous habits and belonged to four families: Dermestidae, Scarabaeidae, Cleridae and Trogidae. Three species, Dermestes maculatus, Necrobia rufipes and Omorgus suberosus are reported for the first time with an expanded geographical distribution that includes the semi-arid region in Brazil. Adult beetles were collected as early as 24h after death. One endemic species, Deltochilum verruciferum, stood out in terms of numerical dominance and temporal occurrence during different stages of decomposition. Its intimate association with carrion emphasizes their potential role in forensic entomology in the region. Copyright © 2012 Elsevier Ireland Ltd. All rights reserved.

  18. The problems of over exploitation of aquifers in semi-arid areas: characteristics and proposals for mitigation

    Energy Technology Data Exchange (ETDEWEB)

    Rodriguez-Estrella, T.


    This article presents a general analysis of the problems arising from overexploited aquifers in semi-arid areas, based on research carried out in the Region of Murcia (one of the most over-exploited areas in Europe). Among the negative impacts of this over exploitation are: the drying up of springs, the continuous drawdown of water levels (up to 10 m/y), piezo metric drops (over 30 m in one year if it is a karstic aquifer), an increase in pumping costs (elevating water from a depth of more than 450 m), abandonment of wells, diminishing groundwater reserves, deteriorating water quality, presence of CO{sub 2}, compartmentalizing of aquifers, etc. A series of internal measures is proposed to alleviate the over exploitation of the region. (Author)

  19. Modeled Impacts of Chronic Wasting Disease on White-Tailed Deer in a Semi-Arid Environment. (United States)

    Foley, Aaron M; Hewitt, David G; DeYoung, Charles A; DeYoung, Randy W; Schnupp, Matthew J


    White-tailed deer are a culturally and economically important game species in North America, especially in South Texas. The recent discovery of chronic wasting disease (CWD) in captive deer facilities in Texas has increased concern about the potential emergence of CWD in free-ranging deer. The concern is exacerbated because much of the South Texas region is a semi-arid environment with variable rainfall, where precipitation is strongly correlated with fawn recruitment. Further, the marginally productive rangelands, in combination with erratic fawn recruitment, results in populations that are frequently density-independent, and thus sensitive to additive mortality. It is unknown how a deer population in semi-arid regions would respond to the presence of CWD. We used long-term empirical datasets from a lightly harvested (2% annual harvest) population in conjunction with 3 prevalence growth rates from CWD afflicted areas (0.26%, 0.83%, and 2.3% increases per year) via a multi-stage partially deterministic model to simulate a deer population for 25 years under four scenarios: 1) without CWD and without harvest, 2) with CWD and without harvest, 3) with CWD and male harvest only, and 4) with CWD and harvest of both sexes. The modeled populations without CWD and without harvest averaged a 1.43% annual increase over 25 years; incorporation of 2% annual harvest of both sexes resulted in a stable population. The model with slowest CWD prevalence rate growth (0.26% annually) without harvest resulted in stable populations but the addition of 1% harvest resulted in population declines. Further, the male age structure in CWD models became skewed to younger age classes. We incorporated fawn:doe ratios from three CWD afflicted areas in Wisconsin and Wyoming into the model with 0.26% annual increase in prevalence and populations did not begin to decline until ~10%, ~16%, and ~26% of deer were harvested annually. Deer populations in variable environments rely on high adult

  20. Modeled Impacts of Chronic Wasting Disease on White-Tailed Deer in a Semi-Arid Environment.

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    Aaron M Foley

    Full Text Available White-tailed deer are a culturally and economically important game species in North America, especially in South Texas. The recent discovery of chronic wasting disease (CWD in captive deer facilities in Texas has increased concern about the potential emergence of CWD in free-ranging deer. The concern is exacerbated because much of the South Texas region is a semi-arid environment with variable rainfall, where precipitation is strongly correlated with fawn recruitment. Further, the marginally productive rangelands, in combination with erratic fawn recruitment, results in populations that are frequently density-independent, and thus sensitive to additive mortality. It is unknown how a deer population in semi-arid regions would respond to the presence of CWD. We used long-term empirical datasets from a lightly harvested (2% annual harvest population in conjunction with 3 prevalence growth rates from CWD afflicted areas (0.26%, 0.83%, and 2.3% increases per year via a multi-stage partially deterministic model to simulate a deer population for 25 years under four scenarios: 1 without CWD and without harvest, 2 with CWD and without harvest, 3 with CWD and male harvest only, and 4 with CWD and harvest of both sexes. The modeled populations without CWD and without harvest averaged a 1.43% annual increase over 25 years; incorporation of 2% annual harvest of both sexes resulted in a stable population. The model with slowest CWD prevalence rate growth (0.26% annually without harvest resulted in stable populations but the addition of 1% harvest resulted in population declines. Further, the male age structure in CWD models became skewed to younger age classes. We incorporated fawn:doe ratios from three CWD afflicted areas in Wisconsin and Wyoming into the model with 0.26% annual increase in prevalence and populations did not begin to decline until ~10%, ~16%, and ~26% of deer were harvested annually. Deer populations in variable environments rely on high

  1. Land use and trophic state dynamics in a tropical semi-arid reservoir

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    Júlio César Neves dos Santos

    Full Text Available Water body eutrophication process has been a serious problem around the world, especially in semiarid and arid region where main approach to storage water is reservoir. The aim of this work was to investigate the spatial and seasonal variability in water quality of a reservoir in a semi-arid tropical region with regards to its trophic state, and to identify the sources of nutrient input to the reservoir. Essa pesquisa foi realizada no reservatório Orós, segundo maior do estado do Ceará-Brasil. This research was developed in the Orós reservoir, the second one most important reservoir in Ceará State, Brazil. Samples were collected bimonthly during the period April 2008 to April 2010, from sex sampling points representing the outlet of tributaries, and one point down of the dam. The study included the following variables: total phosphorus, transparency and chlorophyll-a. Trophic state was evaluated by application of the Carlson modified Trophic State Index (TSI. Maps of the spatial and seasonal dynamics of the water quality in the reservoir were constructed using GIS soft. According to the average values of total phosphorus (> 0.050 mg L-1, the waters can be classified as eutrophic. The highest concentrations of chlorophyll-a were found during the dry season, with values ranging from 3.8 to 26.5 µg L-1, showing high temporal and spatial variations. The waters presented as eutrophic regarding average TSI, at all points sampled. The results indicate a deterioration in water quality and the need for intervention to reduce the release of waste, and thus improve the trophic state of the waters of the Orós reservoir.

  2. Bridging structure and function in semi-arid ecosystems by integrating remote sensing and ground based measurements (United States)

    Krofcheck, Dan J.

    The Southwestern US is projected to continue to experience a significant warming trend, with increased variability in the timing and magnitude of rainfall events. The effects of theses changes in climate are already manifesting in the form of expansive, prolonged 'megadroughts', which have resulted in the widespread mortality of woody vegetation across the region.Therefore the need to monitor and model forest mortality and carbon dynamics at the landscape and regional scale is an essential component of regional and global climate mitigation strategies, and critical if we are to understand how the imminent state transitions taking place in forests globally will affect climate forcing and feedbacks. Remote sensing offers the only solution to multitemporal regional observation, yet many challenges exist with employing modern remote sensing solutions in highly stressed vegetation characteristic of semi-arid biomes, making one of the most expansive biomes on the globe also one of the most difficult to accurately monitor and model. The goal of this research was to investigate how changes in the structure of semi-arid woodlands following forest mortality impacts ecosystem function, and address this question in the context of remote sensing data sets, thereby contributing to the remote sensing community's ability to interact with these challenging ecosystems. We first focused on pinus edulis and juniperous monosperma (pinon-juniper) woodlands, as they comprise a model semi-arid biome. We tested the ability of high resolution remote sensing data to mechanistically describe the patterns in overstory mortality and understory green-up, and were able to observe the heterogeneous response of the understory as a function of cover type. We also investigated the relationship between changes in soil water content and the greenness of the canopy, noting that in these stress ecosystems there is often a decoupling of the canopy as measured remotely (e.g., via vegetation indices, VI

  3. Carbon-cycle implications of asymmetry in response of semi-arid ecosystem phenology and productivity to rainfall (United States)

    Smith, Benjamin; Haverd, Vanessa; Ahlström, Anders; Canadell, Josep


    Semi-arid savannahs and shrublands of the tropics and subtropics play a key role in the inter-annual variability of the global carbon cycle and are emerging as an important player - comparable with tropical forests - in terms of their contribution to the ongoing sink trend of the carbon exchange between the global land surface and atmosphere. Both the variability and carbon balance trend of the savannah-shrubland biome are characterised by shifting phenology, mediated by changes in the seasonality and relative contributions to ecosystem productivity of woody vegetation elements and grasses. Shifts in water availability associated with the impacts of global circulation systems on the distribution and amount of rainfall are a key driver of vegetation response in these ecosystems, which tolerate drought, but spring to life, becoming highly productive, during episodes of ample water supply. This "boom or bust" behaviour with respect to water availability may be expected to translate into an asymmetric response to rainfall change, positive anomalies in rainfall tending to lead to larger increases in productivity compared with the corresponding decrease in productivity resulting from a negative anomaly of comparable size. As rainfall distributions over time themselves exhibit asymmetry, an 'intrinsic' (ecosystem response-driven) and 'extrinsic' (climate or weather forcing-driven) component of asymmetry may be distinguished. We investigated the prevalence of asymmetry in forcing and response of ecosystem productivity to rainfall variability globally and for the illustrative case of Australia, which emerges as a global 'hot spot' for rainfall-driven variability in ecosystem gross primary production (GPP) and associated net ecosystem productivity (NEP). Employing two climate-driven ecosystem models, informed by multiple observation types (land-atmosphere fluxes, biomass, streamflow and remotely-sensed vegetation cover), we show that the inland region of Australia, dominated

  4. Evaluating the Unified Model and JULES in a semi-arid environment (United States)

    Harlow, Chawn; Brooke, Jennifer; Best, Martin; Scott, Russel; Edwards, John; Weeks, Mark


    The Met Office Unified Model (UM) has a significant cold bias in land surface temperature (LST) in semi-arid regions at global resolution, and limited area model (LAM) 4.4 km and 2.2 km configurations. Evaluation of the JULES land surface scheme has been performed for flux tower sites in the Walnut Gulch Experimental Watershed in south-eastern Arizona. Flux tower measurements have shown that JULES simulated turbulent heat fluxes are larger compared with observations (21 W m-2, May monthly average) and ground heat fluxes too small (3.5 W m-2, May monthly average). The accurate representation of the bare soil cover fraction is shown to be of particular importance, reducing biases in the sensible heat flux. Offline simulations with JULES are used to compare UM configurations with observed bare soil and vegetation parameters (surface type fractional cover, leaf area index and canopy height) in order to attribute the LST biases to some model parameter errors. JULES observed vegetation simulations increase the modelled daytime surface warming; daytime LST (O-B) biases are reduced to -0.4 K compared with 4.8 K in the standard configuration simulations when compared with ground-based IRT measurements. Similar trends are seen when the model is compared with MODIS LST retrievals; Aqua LST biases showed a large initial bias of 7.4 K with the standard configuration, reduced to 1.0 K in observed vegetation simulations. The results suggest that there is a large component of the LST bias that is due to errors in the way in which the surface energy balance of sparse vegetation is simulated by JULES. The incorrect specification of vegetation parameters, the fractional coverage of each surface type and soil hydraulic and thermal properties have all been shown to lead to errors in the prediction of surface temperatures.

  5. The role of upland wetlands in modulating snowmelt runoff in the semi-arid Andes (United States)

    Hevia, Andres; Sproles, Eric; Soulsby, Chris; Tetzlaff, Doerthe


    The wetlands, or bofedales, of semi-arid northern central Chile (29°-32°S) provide a critical store of water that modulate spring snowmelt runoff. Water released from bofedales helps sustain flows throughout the dry portions of the year, providing fresh water to downstream residents and a robust tourist, agricultural, and mining economy. In the Río Claro watershed (30°S, 1515 km2, 800m to 5500 m a.s.l.) a series fourteen bofedales have formed at natural choke points in the valley bottoms of the headwater reaches. The highly erosive dynamic of this watershed provides ample sediment, and some of these bofedales are up to 30 m deep. Annual precipitation in the region is limited to 4-6 events annually that fall primarily as snow at elevations above 3500 m. The subsurface storage of the headwaters is limited by the steep terrain of the headwater catchments that are devoid of soils and primarily underlain by granite bedrock. Downstream, irrigated area has increased by 200% between 1985 and 2005, driven by the cultivation of table grapes for export. For over 70 years local water managers have flooded the bodfedales during spring runoff to augment late season flow when irrigation demand peaks. While this low-tech strategy has worked in the past, a recent 8-year drought has raised concerns over long-term water security. We apply geophysical and geographic measurements, water quality, and stable isotopic tracers to calculate the volume of water storage and residence times in the bofedales of Río Claro. This information will be used to evaluate the reliability of the bofedale system as compared to a proposed reservoir in the headwaters of the Río Claro. Additionally, estimating the storage and residence times of the will help reduce uncertainty for modeling efforts currently underway in Río Claro.

  6. Seasonalizing mountain system recharge in semi-arid basins-climate change impacts. (United States)

    Ajami, Hoori; Meixner, Thomas; Dominguez, Francina; Hogan, James; Maddock, Thomas


    Climate variability and change impact groundwater resources by altering recharge rates. In semi-arid Basin and Range systems, this impact is likely to be most pronounced in mountain system recharge (MSR), a process which constitutes a significant component of recharge in these basins. Despite its importance, the physical processes that control MSR have not been fully investigated because of limited observations and the complexity of recharge processes in mountainous catchments. As a result, empirical equations, that provide a basin-wide estimate of mean annual recharge using mean annual precipitation, are often used to estimate MSR. Here North American Regional Reanalysis data are used to develop seasonal recharge estimates using ratios of seasonal (winter vs. summer) precipitation to seasonal actual or potential evapotranspiration. These seasonal recharge estimates compared favorably to seasonal MSR estimates using the fraction of winter vs. summer recharge determined from isotopic data in the Upper San Pedro River Basin, Arizona. Development of hydrologically based seasonal ratios enhanced seasonal recharge predictions and notably allows evaluation of MSR response to changes in seasonal precipitation and temperature because of climate variability and change using Global Climate Model (GCM) climate projections. Results show that prospective variability in MSR depends on GCM precipitation predictions and on higher temperature. Lower seasonal MSR rates projected for 2050-2099 are associated with decreases in summer precipitation and increases in winter temperature. Uncertainty in seasonal MSR predictions arises from the potential evapotranspiration estimation method, the GCM downscaling technique and the exclusion of snowmelt processes. © 2011, The Author(s). Ground Water © 2011, National Ground Water Association.

  7. Coevolution of hydrodynamics, vegetation and channel evolution in wetlands of a semi-arid floodplain (United States)

    Seoane, Manuel; Rodriguez, Jose Fernando; Rojas, Steven Sandi; Saco, Patricia Mabel; Riccardi, Gerardo; Saintilan, Neil; Wen, Li


    The Macquarie Marshes are located in the semi-arid region in north western NSW, Australia, and constitute part of the northern Murray-Darling Basin. The Marshes are comprised of a system of permanent and semi-permanent marshes, swamps and lagoons interconnected by braided channels. The wetland complex serves as nesting place and habitat for many species of water birds, fish, frogs and crustaceans, and portions of the Marshes was listed as internationally important under the Ramsar Convention. Some of the wetlands have undergone degradation over the last four decades, which has been attributed to changes in flow management upstream of the marshes. Among the many characteristics that make this wetland system unique is the occurrence of channel breakdown and channel avulsion, which are associated with decline of river flow in the downstream direction typical of dryland streams. Decrease in river flow can lead to sediment deposition, decrease in channel capacity, vegetative invasion of the channel, overbank flows, and ultimately result in channel breakdown and changes in marsh formation. A similar process on established marshes may also lead to channel avulsion and marsh abandonment, with the subsequent invasion of terrestrial vegetation. All the previous geomorphological evolution processes have an effect on the established ecosystem, which will produce feedbacks on the hydrodynamics of the system and affect the geomorphology in return. In order to simulate the complex dynamics of the marshes we have developed an ecogeomorphological modelling framework that combines hydrodynamic, vegetation and channel evolution modules and in this presentation we provide an update on the status of the model. The hydrodynamic simulation provides spatially distributed values of inundation extent, duration, depth and recurrence to drive a vegetation model based on species preference to hydraulic conditions. It also provides velocities and shear stresses to assess geomorphological

  8. Hydrological response in catchments whit debris covered glaciers in the semi-arid Andes, Chile (United States)

    Caro, A.; McPhee, J.; MacDonell, S.; Pellicciotti, F.; Ayala, A.


    Glaciers in the semi-arid Andes Cordillera in Chile have shrank rapidly during the 20th century. Negative mass balance contributes to increase the surface area of debris-covered glaciers. Recent research in Chile suggests that contributions from glaciers to summer season river flow in dry years is very important, however hydrological processes determining the glacier contribution are still poorly understood in the region. This work seeks to determine appropriate parameters for the simulation of melt volume in two watersheds dominated by debris-covered glaciers, in order to understand its variability in time and space, in the area with the largest population in Chile. The hydrological simulation is performed for the Tapado (30°S) and Pirámide (33ºS) glaciers, which can be defined as cold and temperate respectively. To simulate the hydrological behaviour we adopt the physically-based TOPographic Kinematic wave APproximation model (TOPKAPI-ETH). The hydrometeorological records necessary model runs have been collected through fieldwork from 2013 to 2015. Regarding the calibration of the model parameters melting ETI, its observed that the value for TF in Pirámide is a third of the value for Tapado glacier, while SRF is half in Tapado regarding to Pirámide. The runoff in the glaciers, the constant snow and ice storage are higher in Tapado regarding Pirámide. Results show a contribution of glacial outflow to runoff during 2015 of 55% in Tapado and 77% in Pirámide, with maximum contributions between January and March in Tapado and Pirámide between November and March, presenting the relevance of the permanence of snow cover during spring and shelter that provides debris-covered in reducing the melting glacier. The results have allowed to know the relevance of the glacier contribution to mountain streams, allowing to know the calibration parameters most relevant in the hydrology balance of glacier basins in the Andes.

  9. Landuse Dynamics in a Small Watershed of the Semi-arid Zimbabwe (United States)

    Kileshye-Onema, J.; Rooyen, A. V.


    Zimbabwe has experienced a controversial land reform program with physical, political and socio-economical consequences for the country and the entire southern African region. Here, land use decision making is related to water. A study has been undertaken in Insiza River watershed (3401 km 2), located within the semi-arid southern part of Zimbabwe. The Insiza River is a tributary of Mzingwane River, which drains into the transboundary Limpopo River, contributing around 9 % of the unit runoff of the latter river. The Insiza watershed is divided into two main hydrological zones, the Upper Insiza and the Lower Insiza. Mean Annual Runoff of the two hydrological zones is 50 mm and 38 mm respectively. Through a supervised classification of satellite images, the landuse dynamics was assessed from Landsat images acquired in April 1991 and April 2000. Five signature files, bare ground, water bodies, mixed impacted land, good natural vegetation and croplands were used to define the Insiza watershed land use set up while processing Landsat images with IDRISI. For the decade considered, the major changes occurred within mixed impacted lands that were converted into croplands. This conversion was observed on 14% of the total area of the Insiza watershed. Moreover there was a decrease in water bodies (from 1.3% to 0.89%), bare ground (from 1.2% to 0.9%) and in natural good vegetation (from 50.99% to 50.48%) land types. These changes were observed in the Upper Insiza, where the commercial farms were located. However, the decrease in natural good vegetation and the conversion of mixed impacted lands into fields took place mainly in the communal lands.

  10. An integrative approach to characterize hydrological processes and water quality in a semi-arid watershed in Northeastern Brazil (United States)

    Franklin, M. R.; Fernandes, N.; Veiga, L. H. S.; Melo, L. R.; Santos, A. C. S.; Araujo, V. P.


    Arid and semi-arid regions face serious challenges in the management of scarce water resources. This situation tends to become worse with the increasing population growth rates and consequently increasing water demand. Groundwater is the most important water resource in these areas and, therefore, the sustainability of its use depends on the effectiveness in which it is managed, both in terms of quantity and quality. The Caetité Experimental Basin (CEB), located in a semi-arid region of Northeastern Brazil, faces not only the challenges associated with water scarcity, but also changes in landscape and potential contamination processes due to mining activity. The only active uranium production center in Brazil (URA) is located in this watershed and the sustainability of mining and milling operations as well as the survival of the local community are highly dependent on the availability of groundwater resources. Hydrogeological studies in this area are scarce, and the potential contamination and overexploitation of groundwater can not be ruled out. Therefore, a national project was launched in order to improve the understanding and quantification of the interaction between the hydrogeological system and human health. The methodological approach involved hydrological and geochemical monitoring and characterization of the CEB, use of isotopic techniques, groundwater modeling, water quality diagnosis and human health risk assessment due to water ingestion. The results suggested that the groundwater in the CEB are not totally connected, with evidence of a mixture of recent and old waters. The Na-Ca-HCO3-Cl is the dominant water type (50%) followed by Ca-Na-HCO3-Cl water type (17%). The relevant non-radioactive contaminants are Mn, F, NO3 and Ba, mostly from natural origin, with the exception of NO3 that could be associated with the livestock activities. The estimated effective doses due to groundwater ingestion containing radionuclides are below the recommended

  11. The influence of a semi-arid sub-catchment on suspended sediments in the Mara River, Kenya. (United States)

    Dutton, Christopher L; Subalusky, Amanda L; Anisfeld, Shimon C; Njoroge, Laban; Rosi, Emma J; Post, David M


    The Mara River Basin in East Africa is a trans-boundary basin of international significance experiencing excessive levels of sediment loads. Sediment levels in this river are extremely high (turbidities as high as 6,000 NTU) and appear to be increasing over time. Large wildlife populations, unregulated livestock grazing, and agricultural land conversion are all potential factors increasing sediment loads in the semi-arid portion of the basin. The basin is well-known for its annual wildebeest (Connochaetes taurinus) migration of approximately 1.3 million individuals, but it also has a growing population of hippopotami (Hippopotamus amphibius), which reside within the river and may contribute to the flux of suspended sediments. We used in situ pressure transducers and turbidity sensors to quantify the sediment flux at two sites for the Mara River and investigate the origin of riverine suspended sediment. We found that the combined Middle Mara-Talek catchment, a relatively flat but semi-arid region with large populations of wildlife and domestic cattle, is responsible for 2/3 of the sediment flux. The sediment yield from the combined Middle Mara-Talek catchment is approximately the same as the headwaters, despite receiving less rainfall. There was high monthly variability in suspended sediment fluxes. Although hippopotamus pools are not a major source of suspended sediments under baseflow, they do contribute to short-term variability in suspended sediments. This research identified sources of suspended sediments in the Mara River and important regions of the catchment to target for conservation, and suggests hippopotami may influence riverine sediment dynamics.

  12. Concerns about irrigation efficiency as an adaptation measure to cope with droughts and climate change in semi-arid basins (United States)

    Vicuna, S.; Henriquez, L.; Melo, O.


    As expected in the late 1960s, the Paloma reservoir was built in the Limari basin in the semi-arid region in central Chile with the premise that climate conditions of the past, including the recurrence of dry and wet periods, were going to repeat in the future. That was in fact the case for almost 30 years after the reservoir was built. During this period water supplies from the reservoir were reliable and irrigation efficiency was improved with the result of irrigated land in the basin increasing four times especially with high value-permanent-water-consumption crops (fruits, orchards). Since 2003, during a mega-drought that has affected large proportions of central Chile, inflows to the Paloma reservoir have never again equaled or surpassed average historic flows. The refill of the reservoir, an event that happened every 3-4 years has not occurred in the last 13 years. And the capacity of the basin to accommodate to such a drastic reduction in water availability is no longer present because of the already large "efficient" and permanent use of water. The results in terms of agriculture losses and runoff at the outlet of the basin have been dramatic. Some 400 kms. south of the Limari basin, with higher precipitation levels but still in the semi-arid region in Chile is located the Maipo basin home to the 6 million people city of Santiago and around 250,000 has of irrigated land. Irrigation efficiency is also improving in this basin with savings being used mostly to supply drinking water supply shortages via transfer of water rights. Considering costly infrastructure alternatives, adaptation to climate change projections in this basin will likely extend the improvements in irrigation efficiency most likely affecting downstream environmental uses and reducing overall resilience of the basin to cope with droughts.

  13. Large-scale hydrological modelling in the semi-arid north-east of Brazil (United States)

    Güntner, Andreas


    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

  14. Seasonal variation of carbon fluxes in a sparse savanna in semi arid Sudan

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    El-Tahir Bashir


    Full Text Available Abstract Background Large spatial, seasonal and annual variability of major drivers of the carbon cycle (precipitation, temperature, fire regime and nutrient availability are common in the Sahel region. This causes large variability in net ecosystem exchange and in vegetation productivity, the subsistence basis for a major part of the rural population in Sahel. This study compares the 2005 dry and wet season fluxes of CO2 for a grass land/sparse savanna site in semi arid Sudan and relates these fluxes to water availability and incoming photosynthetic photon flux density (PPFD. Data from this site could complement the current sparse observation network in Africa, a continent where climatic change could significantly impact the future and which constitute a weak link in our understanding of the global carbon cycle. Results The dry season (represented by Julian day 35–46, February 2005 was characterized by low soil moisture availability, low evapotranspiration and a high vapor pressure deficit. The mean daily NEE (net ecosystem exchange, Eq. 1 was -14.7 mmol d-1 for the 12 day period (negative numbers denote sinks, i.e. flux from the atmosphere to the biosphere. The water use efficiency (WUE was 1.6 mmol CO2 mol H2O-1 and the light use efficiency (LUE was 0.95 mmol CO2 mol PPFD-1. Photosynthesis is a weak, but linear function of PPFD. The wet season (represented by Julian day 266–273, September 2005 was, compared to the dry season, characterized by slightly higher soil moisture availability, higher evapotranspiration and a slightly lower vapor pressure deficit. The mean daily NEE was -152 mmol d-1 for the 8 day period. The WUE was lower, 0.97 mmol CO2 mol H2O-1 and the LUE was higher, 7.2 μmol CO2 mmol PPFD-1 during the wet season compared to the dry season. During the wet season photosynthesis increases with PPFD to about 1600 μmol m-2s-1 and then levels off. Conclusion Based on data collected during two short periods, the studied ecosystem

  15. Qualitative soil moisture assessment in semi-arid Africa: the role of experience and training on inter-rater reliability (United States)

    Rinderer, M.; Komakech, H.; Müller, D.; Seibert, J.


    Soil and water management is particularly relevant in semi-arid regions to enhance agricultural productivity. During periods of water scarcity soil moisture differences are important indicators of the soil water deficit and are traditionally used for allocating water resources among farmers of a village community. Here we present a simple, inexpensive soil wetness classification scheme based on qualitative indicators which one can see or touch on the soil surface. It incorporates the local farmers' knowledge on the best soil moisture conditions for seeding and brick making in the semi-arid environment of the study site near Arusha, Tanzania. The scheme was tested twice in 2014 with farmers, students and experts (April: 40 persons, June: 25 persons) for inter-rater reliability, bias of individuals and functional relation between qualitative and quantitative soil moisture values. During the test in April farmers assigned the same wetness class in 46% of all cases while students and experts agreed in about 60% of all cases. Students who had been trained in how to apply the method gained higher inter-rater reliability than their colleagues with only a basic introduction. When repeating the test in June, participants were given improved instructions, organized in small sub-groups, which resulted in a higher inter-rater reliability among farmers. In 66% of all classifications farmers assigned the same wetness class and the spread of class assignments was smaller. This study demonstrates that a wetness classification scheme based on qualitative indicators is a robust tool and can be applied successfully regardless of experience in crop growing and education level when an in-depth introduction and training is provided. The use of a simple and clear layout of the assessment form is important for reliable wetness class assignments.

  16. Qualitative soil moisture assessment in semi-arid Africa - the role of experience and training on inter-rater reliability (United States)

    Rinderer, M.; Komakech, H. C.; Müller, D.; Wiesenberg, G. L. B.; Seibert, J.


    Soil and water management is particularly relevant in semi-arid regions to enhance agricultural productivity. During periods of water scarcity, soil moisture differences are important indicators of the soil water deficit and are traditionally used for allocating water resources among farmers of a village community. Here we present a simple, inexpensive soil wetness classification scheme based on qualitative indicators which one can see or touch on the soil surface. It incorporates the local farmers' knowledge on the best soil moisture conditions for seeding and brick making in the semi-arid environment of the study site near Arusha, Tanzania. The scheme was tested twice in 2014 with farmers, students and experts (April: 40 persons, June: 25 persons) for inter-rater reliability, bias of individuals and functional relation between qualitative and quantitative soil moisture values. During the test in April farmers assigned the same wetness class in 46 % of all cases, while students and experts agreed on about 60 % of all cases. Students who had been trained in how to apply the method gained higher inter-rater reliability than their colleagues with only a basic introduction. When repeating the test in June, participants were given improved instructions, organized in small subgroups, which resulted in a higher inter-rater reliability among farmers. In 66 % of all classifications, farmers assigned the same wetness class and the spread of class assignments was smaller. This study demonstrates that a wetness classification scheme based on qualitative indicators is a robust tool and can be applied successfully regardless of experience in crop growing and education level when an in-depth introduction and training is provided. The use of a simple and clear layout of the assessment form is important for reliable wetness class assignments.

  17. Perched groundwater-surface interactions and their consequences in stream flow generation in a semi-arid headwater catchment (United States)

    Molenat, Jerome; Bouteffeha, Maroua; Raclot, Damien; Bouhlila, Rachida


    In semi-arid headwater catchment, it is usually admitted that stream flow comes predominantly from Hortonian overland flow (infiltration excess overland flow). Consequently, subsurface flow processes, and especially perched or shallow groundwater flow, have not been studied extensively. Here we made the assumption that perched groundwater flow could play a significant role in stream flow generation in semi-arid catchment. To test this assumption, we analyzed stream flow time series of a headwater catchment in the Tunisian Cap Bon region and quantified the flow fraction coming from groundwater discharge and that from overland flow. Furthermore, the dynamics of the perched groundwater was analyzed, by focusing on the different perched groundwater-surface interaction processes : diffuse and local infiltration, diffuse exfiltration, and direct groundwater discharge to the stream channel. This work is based on the 2.6 km² Kamech catchment (Tunisia), which belongs to the long term Mediterranean hydrological observatory OMERE (Voltz and Albergel, 2002). Results show that even though Hortonian overland flow was the main hydrological process governing the stream flow generation, groundwater discharge contribution to the stream channel annually accounted for from 10% to 20 % depending on the year. Furthermore, at some periods, rising of groundwater table to the soil surface in bottom land areas provided evidences of the occurrence of saturation excess overland flow processes during some storm events. Reference Voltz , M. and Albergel , J., 2002. OMERE : Observatoire Méditerranéen de l'Environnement Rural et de l'Eau - Impact des actions anthropiques sur les transferts de masse dans les hydrosystèmes méditerranéens ruraux. Proposition d'Observatoire de Recherche en Environnement, Ministère de la Recherche.

  18. Permafrost distribution modelling in the semi-arid Chilean Andes

    National Research Council Canada - National Science Library

    Azócar, Guillermo F; Brenning, Alexander; Bodin, Xavier


    .... Empirical models of mountain permafrost distribution based on rock glacier activity status and temperature data have been established as a tool for regional-scale assessments of its distribution...

  19. L'économie de la gestion des risques en zone semi-aride

    NARCIS (Netherlands)

    Dijk, van J.W.M.; Tielekes, E.; Schlecht, E.; Hiernaux, P.


    Toute forme de gestion ou d'aménagement des ressources fourragères pour les éleveurs dans la zone semi-aride au Sahel commence obligatoirement par l'appréciation d'un certain nombre de variables et notamment leur variabilité dans l'espace et dans le temps. Cette variabilité est la source d'une vaste

  20. estimating the short-term impact of fire on productivity in a semi-arid ...

    African Journals Online (AJOL)


    It was the objective of this study to estimate the short-term (one year) impact of fire over 10 growing seasons (1995/96. – 2004/05) on the ... managers to determine short-term production loss due to unplanned fires in a semi-arid grassland. This information can ..... PhD thesis, University of Western Australia. 280 pp. Meissner ...

  1. 419 Dynamique structurelle de la végétation en zone semi-aride ...

    African Journals Online (AJOL)

    Geek Store

    2-1-2. Climat. Le climat est du type méditerranéen appartenant à l'étage bioclimatique semi-aride à variante fraîche. La zone est caractérisée par des précipitations moyennes annuelles de 348 mm avec un régime pluviométrique saisonnier de type HPAE (précipitations hivernales > printanières > automnales > estivales) ; ...

  2. Permafrost Distribution Modeling in the Semi-Arid Chilean Andes


    Azócar, Guillermo F.; Brenning, Alexander; Bodin, Xavier


    Mountain permafrost and rock glaciers in the dry Andes are of growing interest due to the increase in human activities in this remote area. Empirical models of mountain permafrost distribution based on the spatial analysis of intact and relict rock glaciers and mean annual air temperature (MAAT) have been established as a tool for regional-scale assessments of permafrost favorability across entire mountain ranges; however, this kind of model approach has never been applied for a large portion...

  3. Permafrost distribution modelling in the semi-arid Chilean Andes


    G. F. Azócar; A. Brenning; X. Bodin


    Mountain permafrost and rock glaciers in the dry Andes are of growing interest due to the increase in mining industry and infrastructure development in this remote area. Empirical models of mountain permafrost distribution based on rock glacier activity status and temperature data have been established as a tool for regional-scale assessments of its distribution; this kind of model approach has never been applied for a large portion of the Andes. In the present study, this m...

  4. Alluvial groundwater recharge estimation in semi-arid environment using remotely sensed data (United States)

    Coelho, Victor Hugo R.; Montenegro, Suzana; Almeida, Cristiano N.; Silva, Bernardo B.; Oliveira, Leidjane M.; Gusmão, Ana Cláudia V.; Freitas, Emerson S.; Montenegro, Abelardo A. A.


    Data limitations on groundwater (GW) recharge over large areas are still a challenge for efficient water resource management, especially in semi-arid regions. Thus, this study seeks to integrate hydrological cycle variables from satellite imagery to estimate the spatial distribution of GW recharge in the Ipanema river basin (IRB), which is located in the State of Pernambuco in Northeast Brazil. Remote sensing data, including monthly maps (2011-2012) of rainfall, runoff and evapotranspiration, are used as input for the water balance method within Geographic Information Systems (GIS). Rainfall data are derived from the TRMM Multi-satellite Precipitation Analysis (TMPA) Version 7 (3B43V7) product and present the same monthly average temporal distributions from 15 rain gauges that are distributed over the study area (r = 0.93 and MAE = 12.7 mm), with annual average estimates of 894.3 (2011) and 300.7 mm (2012). The runoff from the Natural Resources Conservation Service (NRCS) method, which is based on regional soil information and Thematic Mapper (TM) sensor image, represents 29% of the TMPA rainfall that was observed across two years of study. Actual evapotranspiration data, which were provided by the SEBAL application of MODIS images, present annual averages of 1213 (2011) and 1067 (2012) mm. The water balance results reveal a large inter-annual difference in the IRB GW recharge, which is characterized by different rainfall regimes, with averages of 30.4 (2011) and 4.7 (2012) mm year-1. These recharges were mainly observed between January and July in regions with alluvial sediments and highly permeable soils. The GW recharge approach with remote sensing is compared to the WTF (Water Table Fluctuation) method, which is used in an area of alluvium in the IRB. The estimates from these two methods exhibit reliable annual agreement, with average values of 154.6 (WTF) and 124.6 (water balance) mm in 2011. These values correspond to 14.89 and 13.53% of the rainfall that was

  5. Remediation of metalliferous mines, revegetation challenges and emerging prospects in semi-arid and arid conditions. (United States)

    Nirola, Ramkrishna; Megharaj, Mallavarapu; Beecham, Simon; Aryal, Rupak; Thavamani, Palanisami; Vankateswarlu, Kadiyala; Saint, Christopher


    Understanding plant behaviour in polluted soils is critical for the sustainable remediation of metal-polluted sites including abandoned mines. Post-operational and abandoned metal mines particularly in semi-arid and arid zones are one of the major sources of pollution by soil erosion or plant hyperaccumulation bringing ecological impacts. We have selected from the literature 157 species belonging to 50 families to present a global overview of 'plants under action' against heavy metal pollution. Generally, all species of plants that are drought, salt and metal tolerant are candidates of interest to deal with harsh environmental conditions, particularly at semi-arid and arid mine sites. Pioneer metallophytes namely Atriplex nummularia, Atriplex semibaccata, Salsola kali, Phragmites australis and Medicago sativa, representing the taxonomic orders Caryophyllales, Poales and Fabales are evaluated in terms of phytoremediation in this review. Phytoremediation processes, microbial and algal bioremediation, the use and implication of tissue culture and biotechnology are critically examined. Overall, an integration of available remediation plant-based technologies, referred to here as 'integrated remediation technology,' is proposed to be one of the possible ways ahead to effectively address problems of toxic heavy metal pollution. Graphical abstract Integrated remediation technology (IRT) in metal-contaminated semi-arid and arid conditions. The hexagonal red line represents an IRT concept based on remediation decisions by combination of plants and microbial processes.

  6. Effect of high ambient temperature on behavior of sheep under semi-arid tropical environment (United States)

    De, Kalyan; Kumar, Davendra; Saxena, Vijay Kumar; Thirumurugan, Palanisamy; Naqvi, Syed Mohammed Khursheed


    High environmental temperature is a major constraint in sheep production under semi-arid tropical environment. Behavior is the earliest indicator of animal's adaptation and responses to the environmental alteration. Therefore, the objective of this study was to assess the effects of high ambient temperature on the behavior of sheep under a semi-arid tropical environment. The experiment was conducted for 6 weeks on 16 Malpura cross (Garole × Malpura × Malpura (GMM)) rams. The rams were divided equally into two groups, designated as C and T. The rams of C were kept in comfortable environmental conditions served as control. The rams of T were exposed to a different temperature at different hours of the day in a climatic chamber, to simulate a high environmental temperature of summer in semi-arid tropic. The behavioral observations were taken by direct instantaneous observation at 15-min intervals for each animal individually. The feeding, ruminating, standing, and lying behaviors were recorded twice a week from morning (0800 hours) to afternoon (1700 hours) for 6 weeks. Exposure of rams to high temperature (T) significantly ( P animals of T spent significantly ( P behavior of sheep which is directed to circumvent the effect of the stressor.

  7. Spatial distribution of rock glaciers in the semi-arid Andes of Argentina (United States)

    Blöthe, Jan Henrik; Halla, Christian; Schrott, Lothar; Götz, Joachim; Trombotto, Dario


    Active rock glaciers are indicators for permafrost in periglacial environments of high mountain areas. Within the permafrost body and the seasonally frozen active layer, these rock glaciers potentially store large amounts of water. Especially in semiarid mountain belts, such as the central Andes of Argentina, rock glaciers attain several kilometres in length, covering surface areas of >106 m2. Here, rock glaciers even outrange ice glaciers in cumulative area and absolute number, indicating they might constitute a large water reservoir in this semiarid part of the Andes. Despite their potential hydrological importance, our knowledge about the rock glaciers' spatial distribution, subsurface composition and absolute ice content is still very limited. Our study addresses this shortcoming and aims at assessing the hydrological significance of rock glacier permafrost in the semi-arid Andes of Argentina by combining local geophysical investigations with regional remote sensing analysis. Our research focuses on the central Andes between 30°S and 33°S, where we have compiled an inventory that comprises more than 1200 rock glaciers, as well as 154 clear-ice and debris-covered glaciers. Two field sites that bracket this regional study area towards their northern and southern edge have been selected for local geophysical investigations. At these locations, earlier studies detected the presence of rock glacier permafrost by thermal monitoring and geophysical prospection. Preliminary results of the regional spatial distribution indicate that the spatial density of rock glaciers increases towards the south, concomitant with a twofold increase in mean annual precipitation. Rock glacier density peaks in the area of the Aconcagua massif, while precipitation is further increasing towards the south. Simultaneously, the lower altitudinal limit of intact rock glaciers slightly decreases, with the lowest rock glacier toe positions in the northern study area located at ~3800 m a. s. l

  8. Agricultural sustainability in the semi-arid Near East

    Directory of Open Access Journals (Sweden)

    F. Hole


    Full Text Available Agriculture began in the eastern Mediterranean Levantine Corridor about 11000 years ago toward the end of the Younger Dryas when aridity had diminished wild food resources. During the subsequent Climatic Optimum, agricultural villages spread rapidly but subsequent climatic changes on centennial to millennial scales resulted in striking oscillations in settlement, especially in marginal areas. Natural climate change thus alternately enhanced and diminished the agricultural potential of the land. Growing populations and more intensive land us, both for agriculture and livestock, have led to changes in the structure of vegetation, hydrology, and land quality. Over the millennia, political and economic interventions, warfare and incursions by nomadic herding tribes all impacted sustainability of agriculture and the ability of the land to supports its populations. In much of the region today, agricultural land use is not sustainable given existing technology and national priorities. The Near Eastern case is instructive because of the quality of information, the length of the record, and the pace of modern change.

  9. Critical temperature and precipitation thresholds for the onset of xylogenesis of Juniperus przewalskii in a semi-arid area of the north-eastern Tibetan Plateau. (United States)

    Ren, Ping; Rossi, Sergio; Camarero, J Julio; Ellison, Aaron M; Liang, Eryuan; Peñuelas, Josep


    The onset of xylogenesis plays an important role in tree growth and carbon sequestration, and it is thus a key variable in modelling the responses of forest ecosystems to climate change. Temperature regulates the resumption of cambial activity, but little is known about the effect of water availability on the onset of xylogenesis in cold but semi-arid regions. The onset of xylogenesis during 2009-2014 was monitored by weekly microcoring Juniperus przewalskii trees at upper and lower treelines on the north-eastern Tibetan Plateau. A logistic regression was used to calculate the probability of xylogenic activity at a given temperature and a two-dimensional reverse Gaussian model to fit the differences between the observed and estimated days of xylogenesis onset at given temperatures and precipitation within a certain time window. The thermal thresholds at the beginning of the growing season were highly variable, suggesting that temperature was not the only factor initiating xylem growth under cold and dry climatic conditions. The onset of xylogenesis was well predicted for climatic thresholds characterized by a cumulative precipitation of 17.0 ± 5.6 mm and an average minimum temperature of 1.5 ± 1.4 °C for a period of 12 d. Xylogenesis in semi-arid regions with dry winters and springs can start when both critical temperature and precipitation thresholds are reached. Such findings contribute to our knowledge of the environmental drivers of growth resumption that previously had been investigated largely in cold regions without water shortages during early growing seasons. Models of the onset of xylogenesis should include water availability to improve predictions of xylem phenology in dry areas. A mismatch between the thresholds of temperature and moisture for the onset of xylogenesis may increase forest vulnerability in semi-arid areas under forecasted warmer and drier conditions.

  10. Spatial and temporal estimation of runoff in a semi-arid microwatershed of Southern India. (United States)

    Rejani, R; Rao, K V; Osman, M; Chary, G R; Pushpanjali; Reddy, K Sammi; Rao, Ch Srinivasa


    In a semi-arid microwatershed of Warangal district in Southern India, daily runoff was estimated spatially using Soil Conservation Service (SCS)-curve number (CN) method coupled with GIS. The groundwater status in this region is over-exploited, and precise estimation of runoff is very essential to plan interventions for this ungauged microwatershed. Rainfall is the most important factor governing runoff, and 75.8% of the daily rainfall and 92.1% of the rainy days which occurred were below 25 mm/day. The declines in rainfall and rainy days observed in recent years were 9.8 and 8.4%, respectively. The surface runoff estimated from crop land for a period of 57 years varied from 0 to 365 mm with a mean annual runoff of 103.7 mm or 14.1% of the mean annual rainfall. The mean annual runoff showed a significant reduction from 108.7 to 82.9 mm in recent years. The decadal variation of annual runoff from crop land over the years varied from 49.2 to 89.0% which showed the caution needed while planning watershed management works in this microwatershed. Among the four land use land cover conditions prevailing in the area, the higher runoff (20% of the mean annual rainfall) was observed from current fallow in clayey soil and lower runoff of 8.7% from crop land in loamy soil due to the increased canopy coverage. The drought years which occurred during recent years (1991-2007) in crop land have increased by 3.5%, normal years have increased by 15.6%, and the above normal years have decreased by 19.1%. This methodology can be adopted for estimating the runoff potential from similar ungauged watersheds with deficient data. It is concluded that in order to ensure long-term and sustainable groundwater utilization in the region, proper estimation of runoff and implementation of suitable water harvesting measures are the need of the hour.

  11. Interaction between snowcover and climate, topography and vegetation in semi-arid mountain catchments (United States)

    Marks, D.; Pomeroy, J.; Winstral, A.; Link, T.; Seyfried, M.; Essery, R.


    Mountainous regions in the semi-arid Northwestern US are snow-dominated with sparse summer precipitation. Vegetation at high altitudes in this environment is dominated by dry grass and sagebrush with small deciduous and evergreen forest patches in mid-point and lower hillslope locations of north-facing slopes. Wind direction and variations in near-surface wind fields due to topography and vegetation control snow deposition, causing tremendous spatial heterogeneity in the distribution of the snowcover and the delivery of melt water. Snow is scoured from exposed areas during and shortly after storms and deposited in drifts that develop in the lee of exposed ridges, and inward from forest edges. Vegetation cover and soil development is associated with topography and topographic effects on the wind field, in that only sites with sufficient melt-water delivery from drifts and soil moisture storage potential can sustain forests. Forests are typically found down slope from the deepest sections of snowdrifts, where a melt-water supply can replenish soil moisture but where the persistence of snowcover into summer does not impede forest growth. Forest canopies diminish the energy available for melt by reducing turbulent transfer, increasing incoming longwave and reducing incoming shortwave. Hence, snowcover persistence is greatly increased by forest cover - this reduces the growing season and potential evapotranspiration demand over non-forested sites. In contrast, sparsely-vegetated, exposed areas of mountain catchments accumulate less snow, and that snow melts earlier and faster than in forested areas. These hydro-ecological characteristics are very dependent on the snow regime, for instance snow transport is substantial and primarily from one direction resulting in persistent locations for large snow drifts and a relatively reliable water supply for soil development and plant growth. Transport of snow primarily to the north-facing slopes delivers melt-water to sites that

  12. Effects of Precipitation Patterns on Productivity of a Semi-arid Forest (United States)

    Raz Yaseef, N.; Yakir, D.


    Global climate changes are predicted to be associated with both reduced total precipitation and increased storm intensities over many regions, including the entire Mediterranean. The combined effect is difficult to predict and can greatly benefit from studies in dry forest ecosystems exposed to large inter-annual climatic variations. We report on a four year study (2003-2007) in the Yatir semi-arid pine forest in Southern Israel (40 years old P. halepensis; LAI=1.5; mean precipitation 280 mm/yr) that showed resistance to seasonal draughts and carbon uptake capability close to that of the global average for forests (GPP and NEE mean values of 850 and 230 gC/yr respectively). We directly measured soil evaporation (E) using a modified soil respiration chamber (LI-COR) together with continuous eddy flux measurements of evapotranspiration (ET), heat-pulse measurements of tree transpiration (T) and precipitation (P). Soil water content (SWC) was recorded at three pits with TDRs horizontally installed to depth of 130 cm. Precipitation in the research area is characterized by sporadic rain events occurring during the winter months (Nov.-Apr.). Most rain-showers (82%) were smaller than 5 mm, enabling to increase superficial SWC and maintain high moisture level (above 20%) during most of the wet season. In contrast, SWC of the root zone (15-130 cm) depended on larger and less common rainstorms resulting with greater infiltration depths and showing high inter-annual variability. Annual E in this open canopy forest was 102±8 mm and accounted for approximately 44% of ET. T showed somewhat larger inter-annual variability (129±21 mm), clearly associated with storm pattern. Both seasonal and inter-annual trends of T were well synchronized with SWC at the root zone and with GPP. High water holding capacities of the soil resulted in increased SWC at depth only during mid-winter, which due to low E from these depths, was maintained in some cases throughout the dry summer

  13. Impacts of grazing, fire, and precipitation variability on woody plant cover expansion in semi-arid grasslands of southeastern Arizona (United States)

    O'neal, K. J.


    Northern Chihuahuan semi-arid grasslands are highly managed systems supporting rich biodiversity and many endemic species as well as providing a valuable economic resource for cattle-ranching livelihoods, with 90% of grasslands open to grazing. Chihuahuan grasslands share many characteristics with other managed grazing systems, which occupy 25% of the global land surface and are the most extensive form of land use. These grasslands are experiencing land-cover modification from woody plant cover expansion, leading to diminished biodiversity and grazing capacity. Ongoing research indicates that grazing, fire suppression, and precipitation variability are the primary drivers causing increased woody plant cover in Chihuahuan grasslands; however, there is debate concerning the dominant driver. While it is understood that historical land use and climate variation have facilitated initial woody encroachment in the region, the current relative influence of the three drivers remains unclear. This research explores how grazing, fire/suppression, and seasonal precipitation variability influence woody plant cover in the semi-arid grasslands of southeastern Arizona and identifies the dominant driver behind observed changes. This research used the Landsat Thematic Mapper record from 1984 to 2008 to map changes in woody plant cover and identify spatial patterns and temporal trends of woody plant cover expansion. Spectral mixture analysis (SMA) was used to quantify the percent of woody plant cover in each pixel; trend analysis was used to track per-pixel changes over the time-series. Trend analysis was further refined by segmenting trends around fire events to accommodate abrupt and non-monotonic effects of fire on woody plant cover. The overall trend in the region shows increasing woody plant cover with most values ranging between 5-20% over the 25-year period and significant spatial variability in expansion amounts across the region. The Random Forests decision tree approach was

  14. Use of carbon isotope analysis to understand semi-arid erosion dynamics and long-term semi-arid land degradation. (United States)

    Turnbull, Laura; Brazier, Richard E; Wainwright, John; Dixon, Liz; Bol, Roland


    Many semi-arid areas worldwide are becoming degraded, in the form of C(4) grasslands being replaced by C(3) shrublands, which causes an increase in surface runoff and erosion, and altered nutrient cycling, which may affect global biogeochemical cycling. The prevention or control of vegetation transitions is hindered by a lack of understanding of their temporal and spatial dynamics, particularly in terms of interactions between biotic and abiotic processes. This research investigates (1) the effects of soil erosion on the delta(13)C values of soil organic matter (SOM) throughout the soil profile and its implications for reconstructing vegetation change using carbon-isotope analysis and (2) the spatial properties of erosion over a grass-shrub transition to increase understanding of biotic-abiotic interactions by using delta(13)C signals of eroded material as a sediment tracer. Results demonstrate that the soils over grass-shrub transitions are not in steady state. A complex interplay of factors determines the input of SOM to the surface horizon of the soil and its subsequent retention and turnover through the soil profile. A positive correlation between event runoff and delta(13)C signatures of eroded sediment was found in all plots. This indicates that the delta(13)C signatures of eroded sediment may provide a means of distinguishing between changes in erosion dynamics over runoff events of different magnitudes and over different vegetation types. The development of this technique using delta(13)C signatures of eroded sediment provides a new means of furthering existing understanding of erosion dynamics over vegetation transitions. This is critical in terms of understanding biotic-abiotic feedbacks and the evolution of areas subject to vegetation change in semi-arid environments. John Wiley & Sons, Ltd

  15. Influence of Vegetation Cover on Rain Pulse Responses in Semi-Arid Savannas in Central Texas (United States)

    Litvak, M.; Heilman, J.; McInnes, K.; Thijs, A.; Kjelgaard, J.


    Savannas in central Texas are dominated by live oak (Quercus virginiana) and Ashe juniper (Juniperus asheii) underlain by perennial, C3/C4 grasslands, and are increasingly becoming juniper and mesquite dominated due to overgrazing and suppression of wildfires. Since 2004, we have been investigating how carbon, water and energy exchange in these rain-limited savannas respond to rainfall variability and this observed vegetation change. In semi-arid regions, rainfall pulses provide inputs of soil moisture and trigger biotic activity in the form of plant gas exchange and microbial metabolism as well as water dependent physical processes in the soil. Each of these components has a different characteristic response curve to soil moisture and integrates soil water content over a different range of depths. Here we focus on examining how the observed increase of woody species in central Texas savannas alters the response of net ecosystem exchange and its components, ecosystem respiration and gross ecosystem exchange, to rain pulses. Using data we have collected over the last three years from three Ameriflux tower sites at Freeman Ranch near San Marcos, TX (C3/C4 grassland, juniper/mesquite savanna with 50 percent woody cover, and oak/juniper woodland), we quantify the responses of both ecosystem respiration and daily carbon uptake to rainfall pulses throughout the year. Specifically, we look at the enhancement and persistence of ecosystem respiration and carbon uptake responses following a pulse, and isolate the main controlling factors on the observed response: seasonality, antecedent soil moisture and temperature, or previous pulses. In all three land covers, the general response to precipitation pulses is a respiration pulse followed by an increase in total carbon uptake. Differences in pulse responses observed at the savanna site compared to the grassland and woodland sites can be explained, in part, by the observed differences in rooting structure and photosynthetic

  16. Water Governance and Adaptation to Disturbances in Irrigated Semi-Arid Agricultural Systems (United States)

    Evans, T. P.; McCord, P. F.; McBride, L.; Gower, D.; Caylor, K. K.


    Climate and other physical drivers of environmental systems are modifying the global availability of water for irrigation. At the same time population growth is placing an increased demand on water resources as local municipalities promote agricultural production as a mechanism to support human welfare and development. Substantial has research focused on household-level agricultural decision-making and adaptation. But equally important are institutional dynamics, or the rules implemented to allocate water resources across different user groups. Previous work has identified design principles for common-pool resource systems that tend to lead to sustained governance regimes. Likewise, past research has addressed the issue of "institutional fit", or locally adapted governance arrangements characterized through governance structure. However, much of the complexity behind institutional dynamics and adaptive capacity lies in the translation of data to information to knowledge, and how this sequence contributes to effective cross-scale water management and decision-making - an arena that has arguably received less attention in the water management literature. We investigate the interplay between governance regimes, data/information and institutional dynamics in irrigation systems in semi-arid regions of Kenya. In particular, we articulate the role of knowledge and data in institutional dynamics at multiple levels of analysis. How do users at different decision-making levels incorporate social and hydrological information in water governance? What data is needed to develop the information and knowledge users need for effective management? While governance structure is certainly a critical component of water management systems - we emphasize the interplay between the data-information-knowledge sequence and institutional dynamics. We present findings from household and manager-level surveys examining irrigation practices and the institutions designed to equitably allocate

  17. Evaporative loss from irrigated interrows in a highly advective semi-arid agricultural area (United States)

    Agam, Nurit; Evett, Steven R.; Tolk, Judy A.; Kustas, William P.; Colaizzi, Paul D.; Alfieri, Joseph G.; McKee, Lynn G.; Copeland, Karen S.; Howell, Terry A.; Chávez, Jose L.


    Agricultural productivity has increased in the Texas High Plains at the cost of declining water tables, putting at risk the sustainability of the Ogallala Aquifer as a principal source of water for irrigated agriculture. This has led area producers to seek alternative practices that can increase water use efficiency (WUE) through more careful management of water. One potential way of improving WUE is by reducing soil evaporation (E), thus reducing overall evapotranspiration (ET). Before searching for ways to reduce E, it is first important to quantify E and understand the factors that determine its magnitude. The objectives of this study were (1) to quantify E throughout part of the growing season for irrigated cotton in a strongly advective semi-arid region; (2) to study the effects of LAI, days after irrigation, and measurement location within the row on the E/ET fraction; and (3) to study the ability of microlysimeter (ML) measures of E combined with sap flow gage measures of transpiration (T) to accurately estimate ET when compared with weighing lysimeter ET data and to assess the E/T ratio. The research was conducted in an irrigated cotton field at the Conservation & Production Research Laboratory of the USDA-ARS, Bushland, TX. ET was measured by a large weighing lysimeter, and E was measured by 10 microlysimeters that were deployed in two sets of 5 across the interrow. In addition, 10 heat balance sap flow gages were used to determine T. A moderately good agreement was found between the sum E + T and ET (SE = 1 mm or ˜10% of ET). It was found that E may account for >50% of ET during early stages of the growing season (LAI < 0.2), significantly decreasing with increase in LAI to values near 20% at peak LAI of three. Measurement location within the north-south interrows had a distinct effect on the diurnal pattern of E, with a shift in time of peak E from west to east, a pattern that was governed by the solar radiation reaching the soil surface. However, total

  18. Latent heat loss and sweat gland histology of male goats in an equatorial semi-arid environment (United States)

    de Melo Costa, Cíntia Carol; Maia, Alex Sandro Campos; Neto, José Domingues Fontenele; Oliveira, Steffan Edward Octávio; de Queiroz, João Paulo Araújo Fernandes


    The objective of this work was to quantify the heat loss by cutaneous evaporation of goats in an equatorial semi-arid environment. The latent heat loss from the body surfaces of these ten undefined breed goats was measured using a ventilated capsule in sun and shade and in the three body regions (neck, flank and hindquarters). Skin samples from these three regions were histologically analyzed to relate the quantity of sweat glands, the area of sweat glands and the epithelium thickness of each of these regions to the heat loss by cutaneous evaporation of the examined goats. The epithelium thickness that was measured varied significantly for body regions with different quantities and areas of sweat glands ( P < 0.01). Among the body regions that were examined, the samples from the neck demonstrated the highest epithelium thickness (16.23 ± 0.13 μm). However, the samples of sweat glands from the flank had the biggest area (43330.51 ± 778.71 μm2) and quantity per square centimeter (390 ± 9 cm-2). After the animals were exposed to sun, the flanks lost the greatest amount of heat by cutaneous evaporation (73.03 ± 1.75 W m-2) and possessed the highest surface temperatures (39.47 ± 0.18 °C). The histological characteristics may have influenced the heat loss by cutaneous evaporation that was observed in the flank region after the animals were exposed to sun.

  19. Gonotrophic cycle duration, fecundity and parity of Anopheles gambiae complex mosquitoes during an extended period of dry weather in a semi arid area in Baringo County, Kenya.

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    Albert O. Mala


    Full Text Available An entomological longitudinal survey was carried out over a 22 month period in two semi-arid villages in Baringo District in Kenya to study how adult malaria vectors survive under semi-arid conditions and during extended periods of dry weather. Methods Wild caught female mosquitoes were dissected to examine ovarian lobes for parity status and to determine number of gonotrophic cycles they had undergone. Duration of the first and second gonotrophic cycles were estimated using cage-reared F1 females. Blood-fed females were kept individually in plastic vials and percent oviposition incidence recorded. Results Significantly fewer mosquitoes laid eggs during the dry than the wet season. The average duration of the first gonotrophic cycle in the wet season was 4.1 d after blood feeding, 1.1 d (36% longer than the dry season (3.0 d. The average duration of the second gonotrophic cycle in the wet season was 2.9 d after second blood meal, 0.7 d (31.8% longer than those in the dry season. Chi-square tests showed the gonotrophic cycle duration was significantly shorter during the dry than the wet season. Both gonotrophic cycle duration and physiological age varied significantly between wet and dry seasons. Conclusion These findings suggest the duration of gonotrophic cycle among Anopheles gambiae in dry lands with scarce breeding sites is shorter during the dry than wet season. Low fecundity rates during the dry season could be a sign of reduced reproductive activity. However lack of variation in seasonal mating frequency is a clear indication that oviposition and mating kinetics are influenced differently even under the same environmental conditions. It is likely that the results of this study will shed an understanding on spatial and temporal heterogeneities experienced in malaria transmission in semi-arid regions of the world where malaria and indeed mosquito-borne diseases are a public health menace.

  20. Understanding environmental drivers in the regulation of soil respiration dynamics after fire in semi-arid ecosystems (United States)

    Muñoz-Rojas, Miriam; Lewandrowski, Wolfgang; Erickson, Todd E.; Dixon, Kingsley W.; Merritt, David J.


    Keywords: Pilbara, soil CO2 efflux, soil C, soil moisture, soil temperature Introduction Soil respiration (Rs) has become a major research focus given the increase in atmospheric CO2 emissions and the large contribution of these CO2 fluxes from soils (Van Groenigen et al., 2014). In addition to its importance in the global C cycle, Rs is a fundamental indicator of soil health and quality that reflects the level of microbial activity and provides an indication of the ability of soils to support plant growth (Oyonarte et al., 2012; Munoz-Rojas et al., 2015). Wildfires can have a significant impact on Rs rates, with the scale of the impact depending on environmental factors such as temperature and moisture, and organic C content in the soil. Vegetation cover can have a significant effect on regulating organic C contents; and while advances are made into understanding the effects of fire on organic C contents and CO2 fluxes (Granged et al., 2011; Willaarts et al., 2015; Muñoz-Rojas et al., 2016), there is limited knowledge of the variability of Rs across ecosystem types, vegetation communities, and responses to fire. In this research we aimed to assess the impacts of a wildfire on the soil CO2 fluxes and soil respiration in a semi-arid ecosystem of Western Australia (Pilbara biogeographical region), and to understand the main environmental drivers controlling these fluxes in different vegetation types. The study has application for other arid and semi-arid regions of the world. Methods The study area was selected following a wildfire that affected 25 ha in February 2014. Twelve plots were established in the burnt site (B) within a 400 m2 area, and 12 plots in an adjacent unburnt control site. At each site, three plots were installed below the canopy of each of the most representative vegetation types of the areas: Eucalyptus trees, Acacia shrubs and Triodia grasses, and three on bare soil. Soil sampling and measurement of soil CO2 efflux, temperature and moisture were

  1. Estimation of groundwater recharge via deuterium labelling in the semi-arid Cuvelai-Etosha Basin, Namibia. (United States)

    Beyer, Matthias; Gaj, Marcel; Hamutoko, Josefina Tulimeveva; Koeniger, Paul; Wanke, Heike; Himmelsbach, Thomas


    The stable water isotope deuterium ((2)H) was applied as an artificial tracer ((2)H2O) in order to estimate groundwater recharge through the unsaturated zone and describe soil water movement in a semi-arid region of northern central Namibia. A particular focus of this study was to assess the spatiotemporal persistence of the tracer when applied in the field on a small scale under extreme climatic conditions and to propose a method to obtain estimates of recharge in data-scarce regions. At two natural sites that differ in vegetation cover, soil and geology, 500 ml of a 70% (2)H2O solution was irrigated onto water saturated plots. The displacement of the (2)H peak was analyzed 1 and 10 days after an artificial rain event of 20 mm as well as after the rainy season. Results show that it is possible to apply the peak displacement method for the estimation of groundwater recharge rates in semi-arid environments via deuterium labelling. Potential recharge for the rainy season 2013/2014 was calculated as 45 mm a(-1) at 5.6 m depth and 40 mm a(-1) at 0.9 m depth at the two studied sites, respectively. Under saturated conditions, the artificial rain events moved 2.1 and 0.5 m downwards, respectively. The tracer at the deep sand site (site 1) was found after the rainy season at 5.6 m depth, corresponding to a displacement of 3.2 m. This equals in an average travel velocity of 2.8 cm d(-1) during the rainy season at the first site. At the second location, the tracer peak was discovered at 0.9 m depth; displacement was found to be only 0.4 m equalling an average movement of 0.2 cm d(-1) through the unsaturated zone due to an underlying calcrete formation. Tracer recovery after one rainy season was found to be as low as 3.6% at site 1 and 1.9% at site 2. With an in situ measuring technique, a three-dimensional distribution of (2)H after the rainy season could be measured and visualized. This study comprises the first application of the peak displacement method using a

  2. Current and future groundwater withdrawals: Effects, management and energy policy options for a semi-arid Indian watershed (United States)

    Sishodia, Rajendra P.; Shukla, Sanjay; Graham, Wendy D.; Wani, Suhas P.; Jones, James W.; Heaney, James


    Effects of future expansion/intensification of irrigated agriculture on groundwater and surface water levels and availability in a semi-arid watershed were evaluated using an integrated hydrologic model (MIKE SHE/MIKE 11) in conjunction with biophysical measurements. Improved water use efficiency, water storage, and energy policy options were evaluated for their ability to sustain the future (2035) increased groundwater withdrawals. Three future withdrawal scenarios (low = 20, medium = 30, high = 50 wells/100 km2/year) based on the historical rate of growth of irrigation wells were formulated. While well drying from falling groundwater levels was limited to drought and consecutive below average rainfall years, under the current (2015) withdrawals, significant increases in frequency and duration (17-97 days/year) of well drying along with 13-26% (19-37 mm) reductions in surface flows were predicted under the future withdrawals. Higher (27-108%) energy demands of existing irrigation pumps due to declining groundwater levels and reduced hydroelectric generation due to decreased surface flows would create a vicious water-food-energy nexus in the future. Crop failure, one of the main causes of farmers' emotional distress and death in the region, is predicted to exacerbate under the future withdrawal scenarios. Shift to negative net recharge (-63 mm) and early and prolonged drying of wells under the high scenario will reduce the groundwater availability and negatively affect crop production in more than 60% and 90% of cropped areas in the Rabi (November-February) and summer (March-May) seasons, respectively during a drought year. Individual and combined demand (drip irrigation and reduced farm electricity subsidy) and supply (water storage) management options improved groundwater levels and reduced well drying by 55-97 days/year compared to business-as-usual management under the high scenario. The combined management (50% drip conversion, 50% reduction in subsidy, and

  3. Global patterns and environmental controls of perchlorate and nitrate co-occurrence in arid and semi-arid environments (United States)

    Jackson, W Andrew; Böhlke, John Karl; Andraski, Brian J.; Fahlquist, Lynne S.; Bexfield, Laura M.; Eckardt, Frank D.; Gates, John B.; Davila, Alfonso F.; McKay, Christopher P.; Rao, Balaji; Sevanthi, Ritesh; Rajagopalan, Srinath; Estrada, Nubia; Sturchio, Neil C.; Hatzinger, Paul B.; Anderson, Todd A.; Orris, Greta J.; Betancourt, Julio L.; Stonestrom, David A.; Latorre, Claudio; Li, Yanhe; Harvey, Gregory J.


    Natural perchlorate (ClO4−) is of increasing interest due to its wide-spread occurrence on Earth and Mars, yet little information exists on the relative abundance of ClO4− compared to other major anions, its stability, or long-term variations in production that may impact the observed distributions. Our objectives were to evaluate the occurrence and fate of ClO4− in groundwater and soils/caliche in arid and semi-arid environments (southwestern United States, southern Africa, United Arab Emirates, China, Antarctica, and Chile) and the relationship of ClO4− to the more well-studied atmospherically deposited anions NO3−and Cl− as a means to understand the prevalent processes that affect the accumulation of these species over various time scales. ClO4− is globally distributed in soil and groundwater in arid and semi-arid regions on Earth at concentrations ranging from 10−1to 106 μg/kg. Generally, the ClO4− concentration in these regions increases with aridity index, but also depends on the duration of arid conditions. In many arid and semi-arid areas, NO3− and ClO4− co-occur at molar ratios (NO3−/ClO4−) that vary between ∼104and 105. We hypothesize that atmospheric deposition ratios are largely preserved in hyper-arid areas that support little or no biological activity (e.g. plants or bacteria), but can be altered in areas with more active biological processes including N2 fixation, N mineralization, nitrification, denitrification, and microbial ClO4− reduction, as indicated in part by NO3− isotope data. In contrast, much larger ranges of Cl−/ClO4− and Cl−/NO3−ratios indicate Cl− varies independently from both ClO4− and NO3−. The general lack of correlation between Cl− and ClO4− or NO3− implies that Cl− is not a good indicator of co-deposition and should be used with care when interpreting oxyanion cycling in arid systems. The Atacama Desert appears to be unique compared to all other terrestrial locations having a

  4. Avaliação antropométrica e consumo alimentar em crianças menores de cinco anos residentes em um município da região do semiárido nordestino com cobertura parcial do programa bolsa família Anthropometric assessment and food intake of children younger than 5 years of age from a city in the semi-arid area of the Northeastern region of Brazil partially covered by the bolsa família program

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    Silvia Regina Dias Médici Saldiva


    Full Text Available OBJETIVO: Avaliar as condições de saúde e nutrição de crianças menores de cinco anos, e associar a qualidade do consumo alimentar aos beneficiários do Programa Bolsa Família de um município do semiárido brasileiro. MÉTODOS: Foram avaliadas 189 crianças, a partir de uma amostragem de 411 domicílios do município de João Câmara (RN. Foram realizadas medidas de peso e altura, e levantadas às condições socioeconômicas e determinação dos hábitos alimentares. Para o diagnóstico nutricional das crianças foram utilizados os indicadores Peso/Idade, Altura/Idade e Peso/Altura. Análises univariadas foram realizadas e modelos bivariados e multivariados de regressão logística foram construídos para testar a hipótese do estudo. RESULTADOS: O déficit de peso foi de 4,3% e o de altura de 9,9%, e o excesso de peso de 14,0%. Não foram encontradas diferenças estatísticas entre o estado nutricional de crianças beneficiárias e não beneficiárias do Programa Bolsa Família. Em ambos os grupos, os consumos de frutas, verduras e legumes foram baixos e semelhantes entre si. As crianças do programa bolsa família têm risco três vezes maior de consumir guloseimas (OR 3,06 - IC 1,35-6,95. CONCLUSÃO: Os resultados do padrão de consumo alimentar dessa população apontam para uma situação de "risco alimentar e nutricional", e exigem uma intervenção por parte dos profissionais de saúde para a promoção da alimentação saudável.OBJECTIVE: The objective of this study was to assess the health and nutritional status of children under five years of age and to associate the quality of the foods consumed with the Bolsa Família Program in a city located in the Brazilian semi-arid region. METHOD: A total of 189 children from a sample of 411 households in the city of João Câmara (RN were assessed. Weight and height were measured and socioeconomic and food habits were determined with the use of questionnaires. The nutritional status of

  5. Effect of high ambient temperature on behavior of sheep under semi-arid tropical environment. (United States)

    De, Kalyan; Kumar, Davendra; Saxena, Vijay Kumar; Thirumurugan, Palanisamy; Naqvi, Syed Mohammed Khursheed


    High environmental temperature is a major constraint in sheep production under semi-arid tropical environment. Behavior is the earliest indicator of animal's adaptation and responses to the environmental alteration. Therefore, the objective of this study was to assess the effects of high ambient temperature on the behavior of sheep under a semi-arid tropical environment. The experiment was conducted for 6 weeks on 16 Malpura cross (Garole × Malpura × Malpura (GMM)) rams. The rams were divided equally into two groups, designated as C and T. The rams of C were kept in comfortable environmental conditions served as control. The rams of T were exposed to a different temperature at different hours of the day in a climatic chamber, to simulate a high environmental temperature of summer in semi-arid tropic. The behavioral observations were taken by direct instantaneous observation at 15-min intervals for each animal individually. The feeding, ruminating, standing, and lying behaviors were recorded twice a week from morning (0800 hours) to afternoon (1700 hours) for 6 weeks. Exposure of rams to high temperature (T) significantly (P < 0.05) decreased the proportion of time spent in feeding during the observation period in most of the hours of the day as compared to the C. The proportion of time spent in rumination and lying was significantly (P < 0.05) lower in the T group compared to the C. The animals of T spent significantly (P < 0.05) more time in rumination in standing position as compared to the C. The overall proportion of time spent in standing, panting in each hour, and total panting time was significantly (P < 0.05) higher in the T as compared to the C. The result of the study indicates that the exposure of sheep to high ambient temperature severely modulates the behavior of sheep which is directed to circumvent the effect of the stressor.

  6. Groundwater and unsaturated zone evaporation and transpiration in a semi-arid open woodland (United States)

    Balugani, E.; Lubczynski, M. W.; Reyes-Acosta, L.; van der Tol, C.; Francés, A. P.; Metselaar, K.


    Studies on evapotranspiration partitioning under eddy covariance (EC) towers rarely address the separate effects of transpiration and evaporation on groundwater resources. Such partitioning is important to accurately assess groundwater resources, especially in arid and semi-arid areas. The main objective of this study was to partition (evaluate separately) the evaporation and transpiration components of evapotranspiration, originated either from saturated or unsaturated zone, and estimate their contributions in a semi-arid area characterized by relatively shallow groundwater Table (0-10 m deep). Evapotranspiration, tree transpiration and subsurface evaporation were estimated with EC tower, using sap flow methods and HYDRUS1D model, respectively. To set up the HYDRUS1D model, soil material properties, soil moisture, soil temperature, soil matric potential and water table depth were measured in the area. The tree transpiration was sourced into groundwater and unsaturated zone components (∼0.017 mm d-1 for both) and accounted for only ∼6% of the evapotranspiration measured by the EC tower (∼0.565 mm d-1), due to the low canopy coverage in the study area (7%). The subsurface evaporation fluxes were also sourced into groundwater and unsaturated zone components using the SOURCE package, and their relative relevance in total evapotranspiration was assessed. Subsurface evaporation was the main flux year-round (∼0.526 mm d-1). During late autumn, winter and early spring time, the unsaturated zone evaporation was dominant, while in dry summer the relevance of groundwater evaporation increased, reaching one third of evapotranspiration, although errors in the water balance closure point still at its possible underestimation. The results show that, in arid and semi-arid areas with sparse vegetation, the often neglected groundwater evaporation is a relevant contribution to evapotranspiration, and that water vapor flow should be taken into account in the calculation of

  7. Characterization by electrical and electromagnetic geophysical methods of the shallow hydrogeological system at Hebron (West Bank, Palestine) in a semi-arid zone (United States)

    Sirhan, Asal; Hamidi, Mohammad O.


    Multi-electrode geo-electrical and transient electromagnetic surveys were carried out to characterize the nature of the subsurface infiltration zones (5 to 20 m) related to a series of groundwater outlets, and to reveal the geometry of the different aquifers at Bani-Naim, in the south-eastern foothills of the Hebron area, West Bank, Palestine. The purpose of the surveys was to understand the link between water storage/transfer and the characteristics of the geological formations. The strata in this semi-arid region are composed of alternate layers of chalky limestone, hard limestone, marl and chalk. A total of 30 ERT and 15 TDEM were conducted at Bani Naim-Jahir and Bani Naim-Birein. A correlation between the results indicates various infiltration pathways: fractures, feature heterogeneities, and porous chalk. The local heterogeneity on the eastern side were the major pathways for the water infiltration, whereas the thick marl layer underneath acts as a natural impermeable barrier preventing water from infiltrating deeper. A combination of the different geophysical results identified conductive features that correspond to the infiltration zones supplying the dug wells with water. Furthermore, it was established that the fractured chalk and porous chalky limestone act as an aquifer. A three-dimensional visualization of the resistivity allowed a useful reconstruction of the shallow hydrogeological system. Consequently, these studies contribute to regional sustainable development projects in this semi-arid region.

  8. IFOAM Training Manual: Training Manual for Organic Agriculture in the Arid and Semi-arid Tropics


    Weidmann, Gilles; Kilcher, Lukas; Garibay, Salvador V.


    The first IFOAM Training Manual for Organic Agriculture in the Tropics (the Basic Manual) was published in 2004. The Research Institute of Organic Agriculture (FiBL) together with partners of the organic movement in the Tropics were commissioned by IFOAM to complete two new training manuals that build on the Basic Manual. The new IFOAM training manuals address the two basic climatic zones of the Tropics, the Arid and Semi-Arid Tropics, and the Humid Tropics. For both new manuals, already e...

  9. Recovery of microbial community structure and functioning after wildfire in semi-arid environments: optimising methods for monitoring and assessment (United States)

    Muñoz-Rojas, Miriam; Martini, Dylan; Erickson, Todd; Merritt, David; Dixon, Kingsley


    Introduction In semi-arid areas such as northern Western Australia, wildfires are a natural part of the environment and many ecosystems in these landscapes have evolved and developed a strong relationship with fire. Soil microbial communities play a crucial role in ecosystem processes by regulating the cycling of nutrients via decomposition, mineralization, and immobilization processes. Thus, the structure (e.g. soil microbial biomass) and functioning (e.g. soil microbial activity) of microbial communities, as well as their changes after ecosystem disturbance, can be useful indicators of soil quality and health recovery. In this research, we assess the impacts of fire on soil microbial communities and their recovery in a biodiverse semi-arid environment of Western Australia (Pilbara region). New methods for determining soil microbial respiration as an indicator of microbial activity and soil health are also tested. Methodology Soil samples were collected from 10 similar ecosystems in the Pilbara with analogous native vegetation, but differing levels of post-fire disturbance (i.e. 3 months, 1 year, 5, 7 and 14 years after wildfire). Soil microbial activity was measured with the Solvita test which determines soil microbial respiration rate based on the measurement of the CO2 burst of a dry soil after it is moistened. Soils were dried and re-wetted and a CO2 probe was inserted before incubation at constant conditions of 25°C during 24 h. Measurements were taken with a digital mini spectrometer. Microbial (bacteria and fungi) biomass and community composition were measured by phospholipid fatty acid analysis (PLFA). Results Immediately after the fire (i.e. 3 months), soil microbial activity and microbial biomass are similar to 14 years 'undisturbed' levels (53.18±3.68 ppm CO2-CO and 14.07±0.65 mg kg-1, respectively). However, after the first year post-fire, with larger plant productivity, microbial biomass and microbial activity increase rapidly, peaking after 5

  10. Mechanisms Controlling Variability of Lake Salinity in Dune Environments in a Semi-arid Climate: The Nebraska Sand Hills (Invited) (United States)

    Zlotnik, V. A.; Ong, J. T.; Swinehart, J. B.; Fritz, S. C.; Lenters, J. D.; Schmieder, J. U.; Lane, J. W.; Halihan, T.


    Shallow endorheic saline lakes are common in semi-arid environments in North America, Africa, Asia, and Australia. These lakes receive minimal surface runoff and are supported by groundwater seepage. A combination of hydrologic and geologic factors (regional groundwater flow, evaporation, precipitation, lake size, groundwater recharge, and geologic setting) may preclude seepage out of these lakes, even in the presence of ambient regional flow. Solutes from groundwater are captured by these lakes and become enriched over time by evaporation. The importance of understanding lake dynamics in these arid and semi-arid systems is increasing with societal concerns, including water availability and quality, the use of aquatic ecosystems by waterfowl and other biota, and dangers of dust emissions associated with lake desiccation. We consider the salinity of shallow lakes as a useful indicator of hydroclimatic factors operating at centennial and millennial scales. The Nebraska Sand Hills cover 58 000 km2 of the central Great Plains and are the largest dunefield in the Western Hemisphere. The grass-stabilized dunes attain heights up to 130 m and have been modified by soil development and erosion. In an area lakes with surface areas >4 ha and depths lake evaporation exceeds precipitation by 600 mm, according to some estimates. The salinity of natural lakes in the Nebraska Sand Hills ranges from fresh (~0.3 g L-1) to hypersaline (>100 g L-1), with pH values as high as ~10. We assess the mechanisms that control lake salinity in a group of lakes with different subsurface flow regimes. Our methods combine aquifer coring, electromagnetic and electrical resistivity tomography geophysics, hydraulic testing, lakebed dating using 14C and optically stimulated luminescence, energy and water balance analysis, and salt crust and dust collection. Our theory and results show that terrain and water-table topography, lithology, and climate control the lake-aquifer solute exchanges. This study

  11. Fotossensibilização primária em eqüídeos e ruminantes no semi-árido causada por Froelichia humboldtiana (Amaranthaceae Primary photosensitization in equidae and ruminants in the Brazilian semi-arid caused by Froelichia humboldtiana (Amaranthaceae

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    Luciano A. Pimentel


    colocados na mesma pastagem com F. humboldtiana por um período de 44 dias. A égua, que não tinha áreas de pele despigmentadas não apresentou lesões, no entanto o potro desenvolveu dermatite nas áreas brancas de pele 25 dias após o início do pastejo. Após serem retirados da pastagem o potro recuperou-se totalmente em 15 dias. Estes experimentos indicam que F. humboldtiana causa fotossensibilização primária em animais domésticos. A ausência de lesões nos animais que ingeriram a planta após ser coletada e mantida em geladeira sugere que a planta perde sua toxicidade depois da coleta. A ausência de lesões oculares características da intoxicação por furocumarinas sugere que F. humboldtiana contém derivados da naftodiantrona, similares aos encontrados em Fagopyrum esculentum e Hypericum perforatum que não causam lesões oculares.Photosensitization is common in the Brazilian semiarid, affecting mainly horses, but also donkeys, mules, sheep and cattle. The dermatitis affects mainly non pigmented skin, and the animals recover after being withdrawn from the pastures. To demonstrate the etiology of the disease, Froelichia humboldtiana (Roem. et Schult. Seub., collected in the field one or two times a week and kept in the refrigerator for 1-4 days, was administered for 30 or more days as the only food ad libitum to 2 donkeys and one white sheep, and as the only forage ad libitum, to one white horse. No clinical signs were observed in those animals, and serum activities of aspartate-aminotransferase (AST, alanine-aminotransferase (AST, and gamma-glutamyltransferase (GGT were within normal ranges. In another experiment, one sheep was tied by a rope, during the day, in a pasture of exclusively F. humboldtiana for a 26 days period. Skin lesions characteristic of photosensitization appeared 4-5 days after the start of the experiment and became severe until day 26. After the withdrawal of the animal from the pasture on day 26 it fully recovered within 30 days. In

  12. Analysis of soil and vegetation patterns in semi-arid Mediterranean landscapes by way of a conceptual water balance model

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    I. Portoghese


    Full Text Available This paper investigates the impact of various vegetation types on water balance variability in semi-arid Mediterranean landscapes, and the different strategies they may have developed to succeed in such water-limited environments. The existence of preferential associations between soil water holding capacity and vegetation species is assessed through an extensive soil geo-database focused on a study region in Southern Italy. Water balance constraints that dominate the organization of landscapes are investigated by a conceptual bucket approach. The temporal water balance dynamics are modelled, with vegetation water use efficiency being parameterized through the use of empirically obtained crop coefficients as surrogates of vegetation behavior in various developmental stages. Sensitivity analyses with respect to the root zone depth and soil water holding capacity are carried out with the aim of explaining the existence of preferential soil-vegetation associations and, hence, the spatial distribution of vegetation types within the study region. Based on these sensitivity analyses the degrees of suitability and adaptability of each vegetation type to parts of the study region are explored with respect of the soil water holding capacity, and the model results were found consistent with the observed affinity patterns.

  13. A max-to-min technique for making projections of NDVI change in semi-arid Africa for food security early warning (United States)

    Brown, M. E.; Funk, C. C.


    Climatic hazards such as droughts and floods often result in a decline in food production in economically vulnerable pre-industrial economies such as those in Africa. Early warning systems (EWS) have been developed to identify slow onset disasters such famine and epidemic disease that may result from hazardous environmental conditions. These conditions often precede food crises by many months, thus effective monitoring via satellite and in situ observations can allow for successful mitigation activities. Accurate forecasts of NDVI could increase monitoring lead times and allow for effective institutional planning of intervention, making early warning earlier. This paper presents a simple empirical max-to-min model for making 1 to 4 month NDVI projections. These statistical projections are based on parameterized satellite rainfall estimates (RFE) and relative humidity demand (RHD). A heuristic example in central Zimbabwe introduces the RFE growth and RHD loss terms. A quasi-global, one month ahead, 1 degree study then demonstrates reasonable accuracies in many semi-arid regions. In Africa, a 0.1 degree cross-validated skill assessment quantifies the technique's applicability at 1 to 4 month forecast intervals. These results suggest that useful projections can be made over many semi-arid, food insecure regions of Africa, with plausible extensions to drought prone areas of Asia, Australia and South America.

  14. Soil carbon changes after plantation of autochthonous species in a semi-arid Mediterranean old-field in Sardinia (United States)

    de Dato, Giovanbattista; de Angelis, Paolo


    Forested areas are important in arid and semi-arid regions primarily to combat desertification, but also to increase carbon sinks. According to the last Italian National Inventory of Forest and Carbon INFC dated 2005, Mediterranean maquis and shrublands cover about 690,100 ha, in Italy. Considering their vast diffusion, efforts should be done to evaluate the potential of these ecosystems in sequestering C in order to achieve the Kyoto Protocol commitments and dampen desertification processes. The aim of this work was to present preliminary observations on soil C accumulation and release in a planted Mediterranean semi-arid shrubland. During the first three years particular effort was done to quantify the plant growth and soil CO2 emission, to test if species-specific responses could be detectable and relevant for the C-budget. The experimental area is located in North West Sardinia, and is characterized by a Mediterranean climate. The revegetation was set up in February 2006, in an old-field, planting local species (Juniperus phoenicea, Pistacia lentiscus and Rosmarinus officinalis) in mono-specific or mixed plots. Soil total organic carbon and nitrogen was measured at the same time of plantation and after 3 years, collecting soil cores (144 samples) at two depths (0-20 cm and 20-40 cm). Moreover, in order to measure soil CO2 emissions, 4 collars are inserted into the soil at 30-60-90-120 cm from 3 plants per each species. Measurements have being made monthly since July 2006 by a portable IRGA. Presently, soil C in the studied area is about 0.7 - 0.8 t ha-1. Based on soil CO2 emissions measurements (≈7 t C ha-1 yr-1) and on the low biomass accumulation (0.25-0.60 t ha-1 yr-1), the plantation is at the present a net C source. This is an effect of the low plant growth, very little input from litter, and the contemporary mineralization of old C deriving from the preceding agricultural phase (priming effect).

  15. Evaluating Water Controls on Vegetation Growth in the Semi-Arid Sahel Using Field and Earth Observation Data

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    Abdulhakim M. Abdi


    Full Text Available Water loss is a crucial factor for vegetation in the semi-arid Sahel region of Africa. Global satellite-driven estimates of plant CO2 uptake (gross primary productivity, GPP have been found to not accurately account for Sahelian conditions, particularly the impact of canopy water stress. Here, we identify the main biophysical limitations that induce canopy water stress in Sahelian vegetation and evaluate the relationships between field data and Earth observation-derived spectral products for up-scaling GPP. We find that plant-available water and vapor pressure deficit together control the GPP of Sahelian vegetation through their impact on the greening and browning phases. Our results show that a multiple linear regression (MLR GPP model that combines the enhanced vegetation index, land surface temperature, and the short-wave infrared reflectance (Band 7, 2105–2155 nm of the moderate-resolution imaging spectroradiometer satellite sensor was able to explain between 88% and 96% of the variability of eddy covariance flux tower GPP at three Sahelian sites (overall = 89%. The MLR GPP model presented here is potentially scalable at a relatively high spatial and temporal resolution. Given the scarcity of field data on CO2 fluxes in the Sahel, this scalability is important due to the low number of flux towers in the region.

  16. Predicting the future impact of droughts on ungulate populations in arid and semi-arid environments.

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    Clare Duncan

    Full Text Available Droughts can have a severe impact on the dynamics of animal populations, particularly in semi-arid and arid environments where herbivore populations are strongly limited by resource availability. Increased drought intensity under projected climate change scenarios can be expected to reduce the viability of such populations, yet this impact has seldom been quantified. In this study, we aim to fill this gap and assess how the predicted worsening of droughts over the 21(st century is likely to impact the population dynamics of twelve ungulate species occurring in arid and semi-arid habitats. Our results provide support to the hypotheses that more sedentary, grazing and mixed feeding species will be put at high risk from future increases in drought intensity, suggesting that management intervention under these conditions should be targeted towards species possessing these traits. Predictive population models for all sedentary, grazing or mixed feeding species in our study show that their probability of extinction dramatically increases under future emissions scenarios, and that this extinction risk is greater for smaller populations than larger ones. Our study highlights the importance of quantifying the current and future impacts of increasing extreme natural events on populations and species in order to improve our ability to mitigate predicted biodiversity loss under climate change.

  17. Predicting the future impact of droughts on ungulate populations in arid and semi-arid environments. (United States)

    Duncan, Clare; Chauvenet, Aliénor L M; McRae, Louise M; Pettorelli, Nathalie


    Droughts can have a severe impact on the dynamics of animal populations, particularly in semi-arid and arid environments where herbivore populations are strongly limited by resource availability. Increased drought intensity under projected climate change scenarios can be expected to reduce the viability of such populations, yet this impact has seldom been quantified. In this study, we aim to fill this gap and assess how the predicted worsening of droughts over the 21(st) century is likely to impact the population dynamics of twelve ungulate species occurring in arid and semi-arid habitats. Our results provide support to the hypotheses that more sedentary, grazing and mixed feeding species will be put at high risk from future increases in drought intensity, suggesting that management intervention under these conditions should be targeted towards species possessing these traits. Predictive population models for all sedentary, grazing or mixed feeding species in our study show that their probability of extinction dramatically increases under future emissions scenarios, and that this extinction risk is greater for smaller populations than larger ones. Our study highlights the importance of quantifying the current and future impacts of increasing extreme natural events on populations and species in order to improve our ability to mitigate predicted biodiversity loss under climate change.

  18. Ecology and functional roles of biological soil crusts in semi-arid ecosystems of Spain (United States)

    Maestre, Fernando T.; Bowker, Matthew A.; Cantón, Yolanda; Castillo-Monroy, Andrea P.; Cortina, Jordi; Escolar, Cristina; Escudero, Adrián; Lázaro, Roberto; Martínez, Isabel


    Biological soil crusts (BSCs), composed of lichens, cyanobacteria, mosses, liverworts and microorganisms, are key biotic components of arid and semi-arid ecosystems worldwide. Despite they are widespread in Spain, these organisms have been historically understudied in this country. This trend is beginning to change as a recent wave of research has been identifying BSCs as a model ecological system. Many studies and research projects carried out in Spain have explored the role of BSCs on water, carbon and nitrogen fluxes, the interactions between BSCs and vascular plants, their dynamics after disturbances, and their response to global change, among other topics. In this article we review the growing body of research on BSCs available from semi-arid areas of Spain, highlighting its importance for increasing our knowledge on this group of organisms. We also discuss how it is breaking new ground in emerging research areas on the ecology of BSCs, and how it can be use to guide management and restoration efforts. Finally, we provide directions for future research on the ecology of BSCs in Spain and abroad. PMID:25908884

  19. Dry Season Constrains Bacterial Phylogenetic Diversity in a Semi-Arid Rhizosphere System. (United States)

    Taketani, Rodrigo Gouvêa; Lançoni, Milena Duarte; Kavamura, Vanessa Nessner; Durrer, Ademir; Andreote, Fernando Dini; Melo, Itamar Soares


    The rhizosphere is viewed as a deterministic environment led by the interaction between plants and microorganisms. In the case of semi-arid plants, this interaction is strengthened by the harshness of the environment. We tested the hypothesis that dry season represents a constraint on the bacterial diversity of the rhizosphere from semi-arid plants. To accomplish this, we sampled two leguminous species at five locations during the dry and rainy seasons in the Caatinga biome and characterised bacterial community structures using qPCR and 16S rRNA sequencing. We found that the main differences between seasons were due to reduced phylogenetic diversity caused by dryness. Variation partitioning indicated that environmental characteristics significant impacts in β-diversity. Additionally, distance decay relationship and taxa area relationship indicate a higher spatial turnover at the rainy season. During the dry season, decreased bacterial abundance is likely due to the selection of resistant or resilient microorganisms; with the return of the rain, the sensitive populations start to colonise the rhizosphere by a process that is strongly influenced by environmental characteristics. Thus, we propose that the reduction of PD and strong influence of environmental parameters on the assemblage of these communities make them prone to functional losses caused by climatic disturbances.

  20. Climate change mitigation by carbon stock - the case of semi-arid West Africa (United States)

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


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

  1. Do positive interactions increase with abiotic stress? A test from a semi-arid steppe. (United States)

    Maestre, Fernando T; Cortina, Jordi


    Theoretical models predict that the relative importance of facilitation and competition may vary inversely across gradients of abiotic stress. However, these predictions have not been thoroughly tested in the field, especially in semi-arid environments. In this study, we evaluated how the net effect of the tussock grass Stipa tenacissima on the shrub Pistacia lentiscus varied across a gradient of abiotic stress in semi-arid Mediterranean steppes. We fitted the relationship between accumulated rainfall and the relative neighbour index (our measures of abiotic stress and of the net effect of S. tenacissima on P. lentiscus, respectively), which varied across this gradient, to a quadratic model. Competitive interactions dominated at both extremes of the gradient. Our results do not support established theory. Instead, they suggest that a shift from facilitation to competition under high abiotic stress conditions is likely to occur when the levels of the most limiting resource are so low that the benefits provided by the facilitator cannot overcome its own resource uptake. PMID:15504009

  2. Ammonia-oxidising bacteria not archaea dominate nitrification activity in semi-arid agricultural soil. (United States)

    Banning, Natasha C; Maccarone, Linda D; Fisk, Louise M; Murphy, Daniel V


    Ammonia-oxidising archaea (AOA) and bacteria (AOB) are responsible for the rate limiting step in nitrification; a key nitrogen (N) loss pathway in agricultural systems. Dominance of AOA relative to AOB in the amoA gene pool has been reported in many ecosystems, although their relative contributions to nitrification activity are less clear. Here we examined the distribution of AOA and AOB with depth in semi-arid agricultural soils in which soil organic matter content or pH had been altered, and related their distribution to gross nitrification rates. Soil depth had a significant effect on gene abundances, irrespective of management history. Contrary to reports of AOA dominance in soils elsewhere, AOA gene copy numbers were four-fold lower than AOB in the surface (0-10 cm). AOA gene abundance increased with depth while AOB decreased, and sub-soil abundances were approximately equal (10-90 cm). The depth profile of total archaea did not mirror that of AOA, indicating the likely presence of archaea without nitrification capacity in the surface. Gross nitrification rates declined significantly with depth and were positively correlated to AOB but negatively correlated to AOA gene abundances. We conclude that AOB are most likely responsible for regulating nitrification in these semi-arid soils.

  3. Quaternary ecological and geomorphic changes associated with rainfall events in presently semi-arid northeastern Brazil (United States)

    Auler, Augusto S.; Wang, Xianfeng; Edwards, R. Lawrence; Cheng, Hai; Cristalli, Patrícia S.; Smart, Peter L.; Richards, David A.


    Several geomorphic features and palaeobiotic remains in now semi-arid northeastern Brazil indicate major palaeoenvironmental changes during past periods of increased rainfall. 230Th mass spectrometric ages of speleothems and travertines have allowed the determination of the timing and duration of wetter than present conditions. The data demonstrate that wet events have occurred throughout much of the Pleistocene, present dry conditions having been established at the end of the Younger Dryas. A markedly different fauna comprising megafaunal elements not adapted to the present low arboreal scrubland caatinga vegetation existed in the area. Palaeobotanical remains embedded in travertine indicate forested vegetation at these wetter intervals, suggesting that the caatinga was then replaced or mixed with a semi-deciduous forest. Due to the abundance of travertine sites containing fossil botanical remains in northeastern Brazil, it is believed that forest expansion occurred over large areas of the now semi-arid zone, showing that the long hypothesised forested links between biodiversity-rich Amazon and Atlantic rainforests may indeed have existed during these moister phases. Copyright

  4. Impact of climate and analysis of desertification processes in semi arid land in Algeria: using data of Alsat-1 and Landsat (United States)

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


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

  5. Tillage and nitrogen fertilization enhanced belowground carbon allocation and plant nitrogen uptake in a semi-arid canola crop-soil system. (United States)

    Sarker, Jharna Rani; Singh, Bhupinder Pal; He, Xinhua; Fang, Yunying; Li, Guangdi D; Collins, Damian; Cowie, Annette L


    Carbon (C) and nitrogen (N) allocation and assimilation are coupled processes, likely influencing C accumulation, N use efficiency and plant productivity in agro-ecosystems. However, dynamics and responses of these processes to management practices in semi-arid agro-ecosystems are poorly understood. A field-based 13CO2 and urea-15N pulse labelling experiment was conducted to track how C and N allocation and assimilation during canola growth from flowering to maturity were affected by short-term (2-year) tillage (T) and no-till (NT) with or without 100 kg urea-N ha-1 (T-0, T-100, NT-0, NT-100) on a Luvisol in an Australian semi-arid region. The T-100 caused greater (P < 0.05) belowground C allocation and higher (P < 0.05) translocation of soil N to shoots and seeds, compared to other treatments. Microbial N uptake was rapid and greatest in the fertilized (cf. non-fertilized) treatments, followed by a rapid release of microbial immobilized N, thus increasing N availability for plant uptake. In contrast, management practices had insignificant impact on soil C and N stocks, aggregate stability, microbial biomass, and 13C retention in aggregate-size fractions. In conclusion, tillage and N fertilization increased belowground C allocation and crop N uptake and yield, possibly via enhancing root-microbial interactions, with minimal impact on soil properties.


    Directory of Open Access Journals (Sweden)

    Anne Nyambura Karuma


    Full Text Available Conservation of soil moisture through tillage practices is an important management objective for crop production in semi-arid areas. A study to evaluate the effects of tillage practices on maize and bean yields was conducted in Mwala Sub County, Eastern Kenya, in the long (LR and short rains (SR of 2012/13. The tillage treatments were: Disc Ploughing (DP, Disc Ploughing and Harrowing (DPH, Ox-ploughing (OX, Subsoiling – Ripping (SSR, Hand hoeing with Tied Ridges (HTR and Hand hoeing (H only. There were three cropping systems of Sole Maize (SM, Sole Bean (SB and Maize - Bean intercrop (M + B, which were investigated in a Split-Plot Design field experiment with four replications. Data on maize and bean yield and yield components were monitored throughout the four cropping seasons. Maize plant height, leaf area and leaf area index, maize and beans grain and biomass yields were significantly affected by tillage (P SSR > DP > OX > HTR > H, with values ranging from 0.75 Mg ha-1 to 1.46 Mg ha-1 (P < 0.05. Intercropping reduced the seasonal means of bean grain yields (P < 0.05 with a 54 % decrease by intercropping (0.73 Mg ha-1 compared to the sole bean (1.6 Mg ha-1. Thus, the DP and DPH improved crop yield and yield components and can be recommended as tillage practices in the semi-arid region.

  7. Advancements in Hydrology and Erosion Process Understanding and Post-Fire Hydrologic and Erosion Model Development for Semi-Arid Landscapes (United States)

    Williams, C. Jason; Pierson, Frederick B.; Al-Hamdan, Osama Z.; Robichaud, Peter R.; Nearing, Mark A.; Hernandez, Mariano; Weltz, Mark A.; Spaeth, Kenneth E.; Goodrich, David C.


    Fire activity continues to increase in semi-arid regions around the globe. Private and governmental land management entities are challenged with predicting and mitigating post-fire hydrologic and erosion responses on these landscapes. For more than a decade, a team of scientists with the US Department of Agriculture has collaborated on extensive post-fire hydrologic field research and the application of field research to development of post-fire hydrology and erosion predictive technologies. Experiments funded through this research investigated the impacts of fire on vegetation and soils and the effects of these fire-induced changes on infiltration, runoff generation, erodibility, and soil erosion processes. The distribution of study sites spans diverse topography across grassland, shrubland, and woodland landscapes throughout the western United States. Knowledge gleaned from the extensive field experiments was applied to develop and enhance physically-based models for hillslope- to watershed-scale runoff and erosion prediction. Our field research and subsequent data syntheses have identified key knowledge gaps and challenges regarding post-fire hydrology and erosion modeling. Our presentation details some consistent trends across a diverse domain and varying landscape conditions based on our extensive field campaigns. We demonstrate how field data have advanced our understanding of post-fire hydrology and erosion for semi-arid landscapes and highlight remaining key knowledge gaps. Lastly, we briefly show how our well-replicated experimental methodologies have contributed to advancements in hydrologic and erosion model development for the post-fire environment.

  8. Validation of Empirical and Semi-empirical Net Radiation Models versus Observed Data for Cold Semi-arid Climate Condition

    Directory of Open Access Journals (Sweden)

    aliakbar sabziparvar


    Full Text Available Introduction: Solar Net Radiation (Rn is one of the most important component which influences soil heat flux, evapotranspiration rate and hydrological cycle. This parameter (Rn is measured based on the difference between downward and upward shortwave (SW and longwave (LW irradiances reaching the Earth’s surface. Field measurements of Rn are scarce, expensive and difficult due to the instrumental maintenance. As a result, in most research cases, Rn is estimated by the empirical, semi-empirical and physical radiation models. Almorox et al. (2008 suggested a net radiation model based on a linear regression model by using global solar radiation (Rs and sunshine hours. Alados et al. (2003 evaluated the relation between Rn and Rs for Spain. They showed that the models based on shortwave radiation works perfect in estimating solar net radiation. In another work, Irmak et al. (2003 presented two empirical Rn models, which worked with the minimum numbers of weather parameters. They evaluated their models for humid, dry, inland and coastal regions of the United States. They concluded that both Rn models work better than FAO-56 Penman-Monteith model. Sabziparvar et al. (2016 estimated the daily Rn for four climate types in Iran. They examined various net radiation models namely: Wright, Basic Regression Model (BRM, Linacre, Berliand, Irmak, and Monteith. Their results highlighted that on regional averages, the linear BRM model has the superior performance in generating the most accurate daily ET0. They also showed that for 70% of the study sites, the linear Rn models can be reliable candidates instead of sophisticated nonlinear Rn models. Having considered the importance of Rn in determining crop water requirement, the aim of this study is to obtain the best performance Rn model for cold semi-arid climate of Hamedan. Materials and Methods: We employed hourly and daily weather data and Rn data, which were measured du