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Sample records for brazilian semi-arid region

  1. TANNIN POTENCIAL EVALUATION OF SIX FOREST SPECIES OF BRAZILIAN SEMI-ARID REGION

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    Juarez Benigno Paes

    2006-09-01

    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.

  2. Respiratory heat loss in Morada Nova sheep in Brazilian semi-arid regions

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    Steffan Edward Octávio Oliveira

    2013-07-01

    Full Text Available This study aimed to evaluate the respiratory heat loss in sheep from the equations developed for this species and its relations with meteorological variables in semi-arid regions. The respiratory heat loss (sensible and latent was estimated through the equations in the literature for four 12-month-old male Morada Nova sheep, kept in an installation with shading of ceramic tiles and a 3-meter-high ceiling. The following environmental variables were measured: air temperature (TA, wind speed (U, relative humidity (RH and partial vapor pressure (PP{tA}. The physiological variables measured: rectal temperature (TR and respiratory rate (RR. Statistical analysis was performed based on regression using PROC REG procedure in SAS. The latent respiratory heat loss showed a linear and positive correlation with ambient temperature. However, the respiratory convection showed a linear and negative correlation, but with incipient values. Therefore, the latent heat loss is more important than the sensible one in the respiratory system to maintain thermoregulation of sheep in a semi-arid region of Brazil.

  3. NATURAL RESISTANCE OF WOOD OF NINE BRAZILIAN SEMI-ARID REGIONS TREE SPECIES TO SUBTERRANEAN TERMITES, UNDER LABORATORY CONDITION

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    Juarez Benigno Paes

    2003-01-01

    Full Text Available The research evaluated the natural resistance of nine woods of Brazilian semi-aridregion species to subterranean termites, under laboratory condition. The studied species wereProsopis juliflora, Piptadenia macrocarpa, Myracrodruon urundeuva, Schinopsis brasiliensis, Sennasiamea, Tabebuia aurea, Amburana cearenses, Tabebuia impetiginosa and Aspidosperma pyrifolium.Samples measuring 2.54 x 2.00 x 0.64 cm, with the largest measure taken on fiber direction wereobtained from four positions from pith to bark direction. The samples were submitted to the action ofNasutitermes corniger termites for 28 days. The wood resistance to termites attack, with exception ofProsopis juliflora and Tabebuia aurea, was affected by position on pith to bark direction, but was notassociated to wood density. The Aspidosperma pyrifolium and Tabebuia impetiginosa woods werethe more resistance woods. The wood natural resistance was not associated to soluble hot waterextractives content present in the wood of each studied species.

  4. Arbuscular mycorrhizal fungi in Mimosa tenuiflora (Willd. Poir from Brazilian semi-arid

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    Tancredo Augusto Feitosa de Souza

    2016-06-01

    Full Text Available Abstract 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.

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

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

    2016-01-01

    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.

  6. Uses of tree legumes in semi-arid regions

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    Felker, P.

    1980-01-01

    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)

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

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

    2017-03-01

    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.

  8. 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)

    2005-07-15

    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.

  9. Expansive Soil Properties in a Semi-Arid Region

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    MuawiaA. Dafalla

    2012-11-01

    Full Text Available The expansive soils in semi-arid regions are of great concern to design and geotechnical engineers. Range and variations of geotechnical properties of soils are very useful for appropriate design. Saudi Arabia; a semi arid region attracted the attention of researchers and practicing engineers over the last three decades following the rapid urbanizations in different parts of the country. Advanced testing equipments were made available for this study. The research group conducted joint visits with high officials from different municipality authorities to survey the problem and study the extent of damage to various structures. The areas visited included Al Ghatt, Al Zulfi, Al Hofuf, Um Al Sahik, Al Qatif, Tabuk, Tayma and Al Qaleeba. Single and two storey buildings, boundary walls, pavements and asphalt roads suffered significant damage in many parts of the visited locations. This paper presents the outcome of survey and a general review of previous works carried out for swelling clays in Saudi Arabia. Engineering properties for typical soil formation are presented.

  10. Annual plants in arid and semi-arid desert regions

    Institute of Scientific and Technical Information of China (English)

    Xuehua LI; Xiaolan LI; Deming JIANG; Zhimin LIU; Qinghe YU

    2008-01-01

    Annual plants are the main vegetation in arid and semi-arid desert regions.Because of their unique traits,they are the optimal experimental subjects for eco-logical studies.In this article,we summarize annual plants' seed germination strategies,seedling adaptability mechanism to environments,seed dispersal,and soil seed banks.We also discuss the biotic and abiotic factors affecting the composition and dynamics of annual plant populations and communities.Because annual plants have important ecological functions in desert vegetation systems,this study on annual plants will be of great bene-fit to the conservation and restoration of desert ecosys-tems,the rational utilization of resources,and the sustainable development of desert regions.

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

    OpenAIRE

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

    2016-01-01

    Abstract 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 sampl...

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

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    Silva, A. C. S.; Galvão, C. O.; Silva, G. N. S.

    2015-06-01

    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.

  13. 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

    2008-08-01

    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

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

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    Barnhart, Kevin Scott

    2013-10-01

    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 \

  15. Energy and mass transfer parameters in a brazilian semi-arid ecosystem under different thermohydrological conditions

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    Antônio Heriberto de Castro Teixeira

    2015-12-01

    Full Text Available ABSTRACT In the Brazilian semi-arid region, the natural vegetation ("Caatinga" has been replaced by irrigated agriculture, emphasising the importance for quantification of the energy and mass exchanges. Eddy covariance and micro-climatic measurements in this natural ecosystem, were analysed for two years under different thermohydrological conditions. Sensible heat flux (H accounted for 49 and 64% of the net radiation (Rn, respectively, during the wetter and the drier conditions of 2004 and 2005. The corresponding fractions of Rn partitioned as latent heat flux (LE were 40% and 25%. Evapotranspiration (ET in 2004, with 693 mm, represented 96% of precipitation (P, while in 2005 (399 mm, it was 18% higher than P, which evidenced the use of the remaining soil moisture from the previous wetter year. All the soil-water-vegetation-atmosphere transfer parameters were influenced by the rainfall amounts. However, the surface resistance (rs was the most strongly affected by the soil moisture status, dropping with increases of the ratio of ET to reference evapotranspiration (ET0. On the other hand, the highest rs values were related to increases in both vapour pressure deficit (De and aerodynamic temperature (T0. The current research aimed to quantify the energy and mass exchange between the "Caatinga" and the lower atmosphere, testing in which circumstances the biophysical controlling parameters can be reasonably predicted from agrometeorological data, throughout parameterizations, to incorporate in large-scale models.

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

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

    2015-12-01

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

  17. Resistência natural de nove madeiras do semi-árido brasileiro a fungos causadores da podridão-mole Natural resistance of nine woods of Brazilian semi-arid region to soft-rot fungi

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    Juarez Benigno Paes

    2005-06-01

    Full Text Available O objetivo desta pesquisa foi avaliar a resistência de nove madeiras de ocorrência no semi-árido brasileiro a fungos de podridão-mole, em condições de laboratório. As madeiras estudadas foram algaroba (Prosopis juliflora, angico (Anadenanthera colubrina var. cebil, aroeira (Myracrodruon urundeuva, braúna (Schinopsis brasiliensis, cássia (Senna siamea, craibeira (Tabebuia aurea, cumaru (Amburana cearensis, pau-d'arco (Tabebuia impetiginosa e pereiro (Aspidosperma pyrifolium. De cada espécie foram retirados corpos-de-prova de 3,0 x 1,5 x 0,5 cm, com a maior dimensão no sentido das fibras, em quatro posições na direção medula-casca do tronco. As amostras permaneceram por 120 dias sob a ação da microflora natural existente em solo orgânico. A resistência ao apodrecimento da aroeira, braúna e cássia não foi afetada pela posição na direção medula-casca, não esteve relacionada à densidade das madeiras ensaiadas. As madeiras de aroeira e braúna (cerne, pereiro e pau-d'arco apresentaram melhor desempenho. A resistência natural não esteve associada à concentração de extrativos solúveis em água quente.The objective of this research was to evaluate the wood natural resistance of nine species of woods of the Brazilian semi-arid region to soft-rot fungi, under laboratory conditions. The studied woods were Prosopis juliflora, Anadenanthera colubrinavar.cebil, Myracrodruon urundeuva, Schinopsis brasiliensis, Senna siamea, Tabebuia aurea, Amburana cearensis, Tabebuia impetiginosa and Aspidosperma pyrifolium. Specimens measuring 3.0 x 1.5 x 0.5 cm, with the largest dimension taken in the fiber direction, were obtained from four positions from pith to bark in the trunk. The specimens were submitted to action of organic soil natural micro-flora for 120 days. The wood resistance to soft-rot of Myracrodruon urundeuva, Schinopsis brasiliensis and Senna siameawas not affected by the pith to bark position, and was not associated to

  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

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    Carlos Antonio Fernandes Santos

    2010-06-01

    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

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    Márcio Sampaio Pimentel

    2012-04-01

    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. A methodology to assess and evaluate rainwater harvesting techniques in (semi-) arid regions

    NARCIS (Netherlands)

    Adham, Ammar; Riksen, Michel; Ouessar, Mohamed; Ritsema, Coen J.

    2016-01-01

    Arid and semi-arid regions around the world face 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. Researchers have used many different methodologie

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

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

    2004-01-01

    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 dependenc

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

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    Jessica Roberts Fonseca

    2015-03-01

    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.

  3. 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

    2002-03-01

    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)

  4. The Araceae in Ceará, Brazil: humid forest plants in a semi-arid region

    OpenAIRE

    Andrade,Ivanilza Moreira de; Mayo,Simon Joseph; Silva, Maria Francilene Souza; Sousa,Danilo José Lima de; Matias,Lígia Queiroz; Ribeiro,Thales Alves

    2013-01-01

    The study consists of a taxonomic treatment of the Araceae of Ceará, a state lying within Brazil's semi-arid region. The aroid flora shows greater similarity to those of central Brazil and Amazonia than to the Atlantic forest. Most species occur in humid forest fragments - the "florestas serranas". Geophytes are also found in caatinga and dry forest (Taccarum ulei) and lithophytes on rock outcrops in dry forest (Philodendron acutatum). Floating aquatics occur in ponds and lakes throughout the...

  5. Effect of irrigation systems on temporal distribution of malaria vectors in semi-arid regions.

    Science.gov (United States)

    Ohta, Shunji; Kaga, Takumi

    2014-04-01

    Previous research models have used climate data to explain habitat conditions of Anopheles mosquitoes transmitting malaria parasites. Although they can estimate mosquito populations with sufficient accuracy in many areas, observational data show that there is a tendency to underestimate the active growth and reproduction period of mosquitoes in semi-arid agricultural regions. In this study, a new, modified model that includes irrigation as a factor was developed to predict the active growing period of mosquitoes more precisely than the base model for ecophysiological and climatological distribution of mosquito generations (ECD-mg). Five sites with complete sets of observational data were selected in semi-arid regions of India for the comparison. The active growing period of mosquitoes determined from the modified ECD-mg model that incorporated the irrigation factor was in agreement with the observational data, whereas the active growing period was underestimated by the previous ECD-mg model that did not incorporate irrigation. This suggests that anthropogenic changes in the water supply due to extensive irrigation can encourage the growth of Anopheles mosquitoes through the alteration of the natural water balance in their habitat. In addition, it was found that the irrigation systems not only enable the active growth of mosquitoes in dry seasons but also play an important role in stabilizing the growth in rainy seasons. Consequently, the irrigation systems could lengthen the annual growing period of Anopheles mosquitoes and increase the maximum generation number of mosquitoes in semi-arid subtropical regions.

  6. ARBUSCULAR MYCORRHIZAL FUNGI IN SUCCESSIONAL STAGES OF CAATINGA IN THE SEMI-ARID REGION OF BRAZIL

    Directory of Open Access Journals (Sweden)

    Carla da Silva Sousa

    2014-03-01

    Full Text Available http://dx.doi.org/10.5902/1980509813331Caatinga 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

  7. Sources of water used by natural mesquite vegetation in a semi-arid region of northern Mexico

    OpenAIRE

    2009-01-01

    Vegetation structure in semi-arid regions of northern Mexico and the southwestern USA has changed dramatically over the last century; shrubs such as mesquite (Prosopis sp.) have expanded into, and have become dominant in, ecosystems that once supported semi-arid grassland. The upper San Pedro River watershed, which extends from northern Sonora (Mexico) to southeastern Arizona (USA), highlights these changes. Between 1973 and 1992, grasslands decreased by 18% and the total area dominated by me...

  8. Discussion on an Eco-Agriculture Model in the Semi-Arid Region of China

    Institute of Scientific and Technical Information of China (English)

    ZhangPeidong

    2005-01-01

    The semi-arid region of China covers an area of 2.2×106kin2. Water shortage in this region is the core but not the only one factor for the sustainable development of agriculture. Effective application of the energy and all kinds of resources and overall maintenance of the balance of ecological environment must be emphasized for sustainable development of the agriculture in the region. The extensive development of rural yard-economy is the only way to realize the intensive agricultural development there. A model is developed on the basis of our studies in recent years.

  9. Assessment of the performance of water harvesting systems in semi-arid regions

    Science.gov (United States)

    Lasage, Ralph

    2016-04-01

    Water harvesting is widely practiced and has the potential 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, for meeting the Sustainable Development Goals and to help communities to adapt to climate change. For this, it is important to understand which factors determine the success of water harvesting techniques under different conditions. For this, we review the literature, including information on the crop yield impacts of water harvesting projects in semi-arid Africa and Asia. Results show that large water harvesting structures (> 500 m3) are less expensive than small structures, when taking into account investment costs, storage capacity and lifetimes. We also find that water harvesting improves crop yields significantly, and that the relative impact of water harvesting on crop yields is largest in low rainfall years. We also see that the governance, technical knowledge and initial investment are more demanding for the larger structures than for smaller structures, which may affect their spontaneous adoption and long term sustainability when managed by local communities. To support the selection of appropriate techniques, we present a decision framework based on case specific characteristics. This framework can also be used when reporting and evaluating the performance of water harvesting techniques, which is up to now quite limited in peer reviewed literature. Based on Bouma, J., Hegde, S.E., Lasage, R., (2016). Assessing the returns to water harvesting: A meta-analysis. Agricultural Water Management 163, 100-109. Lasage, R., Verburg P.H., (2015). Evaluation of small scale water harvesting techniques for semi-arid environments. Journal of Arid Environments 118, 48-57.

  10. A Methodology to Assess and Evaluate Rainwater Harvesting Techniques in (Semi- Arid Regions

    Directory of Open Access Journals (Sweden)

    Ammar Adham

    2016-05-01

    Full Text Available Arid and semi-arid regions around the world face 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. Researchers have used many different methodologies for determining suitable sites and techniques for RWH. However, limited attention has been given to the evaluation of RWH structure performance. The aim of this research was to design a scientifically-based, generally applicable methodology to better evaluate the performance of existing RWH techniques in (semi- arid regions. The methodology integrates engineering, biophysical and socio-economic criteria using the Analytical Hierarchy Process (AHP supported by the Geographic Information System (GIS. Jessour/Tabias are the most traditional RWH techniques in the Oum Zessar watershed in south-eastern Tunisia, which were used to test this evaluation tool. Fifty-eight RWH locations (14 jessr and 44 tabia in three main sub-catchments of the watershed were assessed and evaluated. Based on the criteria selected, more than 95% of the assessed sites received low or moderate suitability scores, with only two sites receiving high suitability scores. This integrated methodology, which is highly flexible, saves time and costs, is easy to adapt to different regions and can support designers and decision makers aiming to improve the performance of existing and new RWH sites.

  11. 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

    2010-01-01

    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

  12. Satellite-based analysis of recent trends in the ecohydrology of a semi-arid region

    Directory of Open Access Journals (Sweden)

    M. Gokmen

    2013-10-01

    Full Text Available We present a regional framework for an integrated and spatiotemporally distributed assessment of human-induced trends in the hydrology and the associated ecological health of a semi-arid basin where both human activities (i.e. agriculture and natural ecosystems are highly groundwater dependent. To achieve this, we analysed the recent trends (from year 2000 to 2010 in precipitation, evapotranspiration (actual and potential and vegetation greenness (i.e. NDVI using a combination of satellite and ground-based observations. The trend assessment was applied for the semi-arid Konya Basin (Turkey, one of the largest endorheic basins in the world. The results revealed a consistent increasing trend of both yearly evapotranspiration (totally 63 MCM yr−1 from croplands and mean NDVI (about 0.004 NDVI yr−1 in irrigated croplands, especially concentrating in the plain part of the basin, while no significant trends were observed for the precipitation and potential evapotranspiration variables. On the contrary, a consistent decreasing trend of both yearly evapotranspiration (totally −2.1 MCM yr−1 and mean NDVI (−0.001 NDVI yr−1 was observed in the wetlands, which also cannot be explained by trends in precipitation and potential evapotranspiration. The emerging picture suggest that the greening trend of the vegetation and increasing of evapotranspiration in the plain are related to land cover changes (i.e. conversion into irrigated croplands and to the intensification of the supplementary irrigation for agriculture, which in turn caused drying out of some wetlands and the natural vegetation which mostly depend on the groundwater, the main source of irrigation water as well. Our study presented an example of the utility of spatially and temporally continuous RS data in assessing the regional trends in hydrological and ecological variables and their interactions in a spatially distributed manner in a semi-arid region, which can also be adapted to

  13. Analysis and evaluation of tillage on an alfisol ina semi-arid tropical region of India

    NARCIS (Netherlands)

    Klaij, M.C.

    1983-01-01

    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 experiments into per

  14. Agricultural water productivity optimization for irrigated Teff (Eragrostic Tef) in water scarce semi-arid region of EthiopiaAgricultural water productivity optimization for irrigated Teff (Eragrostic Tef) in water scarce semi-arid region of Ethiopia

    NARCIS (Netherlands)

    Yihun, Y.M.

    2015-01-01

    Title of the PhD Thesis: ‘Agricultural Water Productivity Optimization for Irrigated Teff (Eragrostic Tef) in water Scarce Semi-Arid region of Ethiopia’ Yenesew Mengiste Yihun In water stressed regions such as the Central Rift Valley of Ethiopia, increasing Crop Water Productivity (CWP)

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

    Science.gov (United States)

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

    2015-09-01

    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. Determine the optimum spectral reflectance of juniper and pistachio in arid and semi-arid region

    Science.gov (United States)

    Fadaei, Hadi; Suzuki, Rikie

    2012-11-01

    Arid and semi-arid areas of northeast Iran cover about 3.4 million ha are populated by two main tree species, the broadleaf Pistacia vera. L (pistachio) and the conifer Juniperus excelsa ssp. polycarpos (Persian juniper). Natural stands of pistachio in Iran are not only environmentally important but genetically essential as seed sources for pistachio production in orchards. In this study, we estimated the optimum spectral reflectance of juniper forests and natural pistachio stands using remote sensing to help in the sustainable management and production of pistachio in Iran. In this research spectral reflectance are able to specify of multispectral from Advanced Land Observing Satellite (ALOS) that provided by JAXA. These data included PRISM is a panchromatic radiometer with a 2.5 m spatial resolution at nadir, has one band with a wavelength of 0.52-0.77 μm and AVNIR-2 is a visible and near infrared radiometer for observing land and coastal zones with a 10 m spatial resolution at nadir, has four multispectral bands: blue (0.42-0.50 μm), green (0.52-0.60 μm), red (0.61-0.69 μm), and near infrared (0.76-0.89 μm). Total ratio vegetation index (TRVI) of optimum spectral reflectance of juniper and pistachio have been evaluated. The result of TRVI for Pistachio and juniper were (R2= 0.71 and 0.55). I hope this research can provide decision of managers to helping sustainable management for arid and semi-arid regions in Iran.

  17. Regional integrated modelling of climate change impacts on natural resources and resource usage in semi-arid Northeast Brazil

    NARCIS (Netherlands)

    Krol, Maarten S.; Bronstert, Axel

    2007-01-01

    Semi-arid regions are characterised by a high vulnerability of natural resources to climate change, pronounced climatic variability and often by water scarcity and related social stress. The analysis of the dynamics of natural conditions and the assessment of possible strategies to cope with drought

  18. The current bioenergy production potential of semi-arid and arid regions in sub-Saharan Africa

    NARCIS (Netherlands)

    Wicke, B.; Smeets, E.M.W.; Watson, H.; Faaij, A.P.C.

    2011-01-01

    This article assesses the current technical and economic potential of three bioenergy production systems (cassava ethanol, jatropha oil and fuelwood) in semi-arid and arid regions of eight sub-Saharan African countries. The results indicate that the availability of land for energy production ranges

  19. Predictability and prediction of summer rainfall in the arid and semi-arid regions of China

    Science.gov (United States)

    Xing, Wen; Wang, Bin

    2016-09-01

    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.

  20. Architectural typologies of the handmade cheese makers in the semi-arid region, at Alagoas state, Brazil

    OpenAIRE

    Mendonça, Ariadne Aguiar Vitório; Toledo, Alexandre Márcio

    2011-01-01

    This paper presents the architectonic typology of the handcraft cheese factories of the semi-arid region of Alagoas, relating and verifying the result of the changes on the structure, especially because of the demanding of the rules concerning hygiene and food safety on dairy products. The goal is to identify the typological categories and relate them to the way the handcrafted cheese is made (“queijo coalho” and “queijo manteiga”), according to the regulations. The rural architecture was bas...

  1. Decomposição e liberação de nutrientes de coquetéis vegetais para utilização no Semiárido brasileiro The decomposition and release of nutrients by plant mixtures in the Brazilian semi-arid regions

    Directory of Open Access Journals (Sweden)

    Vanderlise Giongo

    2011-09-01

    Full Text Available A decomposição e liberação de nutrientes de resíduos vegetais podem assumir importante papel no manejo da fertilidade dos solos da região semiárida. Portanto, o presente estudo teve por objetivo avaliar a taxa de decomposição da matéria seca (MS e liberação de carbono (C e nutrientes de coquetéis vegetais no Semiárido brasileiro. O experimento foi conduzido em casa de vegetação, no período de novembro de 2007 a junho de 2008, com coquetéis vegetais compostos por espécies de leguminosas (L (calopogônio, Crotalaria juncea, Crotalaria spectabilis, feijão de porco, guandu, lab-lab e não leguminosas (NL (gergelim, girassol, mamona, milheto e sorgo, combinados nos seguintes tratamentos: T1 - 100% NL; T2 - 100% L; T3 - 75% L e 25% NL; T 4 - 50% L e 50% NL; T5 - 25% L e 75% NL. As taxas de decomposição da MS e liberação dos nutrientes foram monitoradas por meio de coleta dos resíduos, realizadas aos 8; 15; 30; 60; 90; 120; 150; 180 e 210 dias após o início do experimento. Utilizou-se o delineamento experimental em blocos casualizados com três repetições. Os coquetéis apresentaram taxas de decomposição de MS e liberação de nutrientes semelhantes, exceto para Ca, Cu e Mn, em que os coquetéis compostos com predominância de espécies NL apresentaram liberação mais rápida. A partir da média dos valores de k para todos os coquetéis estabeleceu-se a seguinte ordem de liberação de macronutrientes: K > N > Ca > Mg > P e de micronutrientes: Fe > Mn > Cu > Zn > B.The decomposition and release of nutrients from plant residues can play an important role in the maintenance of soil fertility in semi-arid regions. Thus this study aimed to evaluate the rate of decomposition of dry matter (DM and the release of carbon (C and nutrients from plant mixtures used as green manure in the Brazilian Semi-arid regions. The experiment was carried out in a greenhouse, from November 2007 to July 2008, using plant mixtures made up of

  2. Holocene semi-arid oak woodlands in the Irano-Anatolian region of Southwest Asia: natural or anthropogenic?

    Science.gov (United States)

    Asouti, Eleni; Kabukcu, Ceren

    2014-04-01

    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

  3. Monitoring small reservoirs in semi-arid region by satellite SAR data

    Science.gov (United States)

    Nicolina Papa, Maria; Mitidieri, Francesco; Amitrano, Donato; Ruello, Giuseppe; Di Martino, Gerardo; Iodice, Antonio; Riccio, Daniele

    2016-04-01

    The work presents a novel tool for the monitoring of small reservoirs in semi-arid regions. The pilot project was developed in the Yatenga region, a Sahelian area in northern Burkina Faso. In semi-arid regions, small reservoirs are widely employed for facing seasonal variability in water availability due to the alternation of a rainy (3 months) and a dry (9 months) season. Beside their crucial importance, the small reservoirs are not appropriately monitored, they are often built for the initiative of small local communities and even basic data as their location and capacity are not available. Another major problem is linked to soil erosion due to water and consequent reservoirs' sedimentation that reduces the amount of available water and the life span of reservoirs. This lack of data prevents the implementation of strategies for the optimization of water resources management. It is therefore necessary to improve the data availability through the development of cost-effective monitoring techniques and to adapt the hydrological modeling to the limited available data. In this context the use if satellite data can highly contribute to the achievement of crucial information at low costs, high resolution in time and wide areas. In the present work, we used COSMO-SkyMed Stripmap (3m resolution) and Spotligth (1m resolution) Synthetic Aperture Radar (SAR) data acquired under the aegis of the 2007 Italian Space Agency Announcement of Opportunity and of the HydroCIDOT project. The shorelines of the reservoirs were extracted from the series of SAR images by employing an innovative change-detection framework. A digital elevation model (DEM) of the study area was obtained via standard interferometry processing of images acquired at the end of the dry season, when small reservoirs are completely empty, and information about the surface usually covered by water can be retrieved. The obtained DEM and shorelines were used for bathymetry extraction of reservoirs. For the

  4. Modelling long-term sustainability of irrigation practices in semi arid region

    Science.gov (United States)

    Guyennon, Nicolas; Romano, Emanuele; Portoghese, Ivan

    2016-04-01

    The impact of climate change on groundwater or surface water resources can be investigated through models simulating the hydrological and hydrogeological processes at the atmosphere/surface water/soil/groundwater interfaces. However, in aquifers extensively exploited for irrigation purposes, the water demand variability related to actual water availability, as well as to variation of the crops, and associated supply management options should be considered to evaluate impacts. Moreover, in the case of a multi-resources water supply system it is necessary to develop models able to simulate also the variation of the total demand distribution among each resource. We proposed a modeling scheme able to simulate an integrated multiple-resources and multiple-purposes water supply system by merging distributed crop water requirements with surface reservoir and ground water mass balance, considering resources availability and management, with emphasis on irrigation practices. The overall framework has been implemented for the case study of the Fortore water supply system, a semi-arid region in south Italy. It permits to simulate the conjunctive use of the water from the Occhito artificial reservoir (160 Mm3) and from groundwater to supply domestic, industrial and agricultural demand. The overall model successfully reproduces the Occhito dam level variability (both seasonal and inter-annual) as well as the observed groundwater depletion. The proposed model was forced by 60 years of meteorological observation to test the long-term sustainability of the current irrigation practices and has been extended to the next decades under a1b IPCC scenario using three ENSEMBLES member to test adaptation strategies.

  5. ENERGETIC VALUE OF FORAGES FROM SEMI-ARID REGION AND DIGESTIBILITY OF RATIONS FOR NAKED NECK PULLETS

    Directory of Open Access Journals (Sweden)

    ALEX MARTINS VARELA DE ARRUDA

    2014-01-01

    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.

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

    Directory of Open Access Journals (Sweden)

    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.

  7. Keeping Sediment and Nutrients out of Streams in Arid/Semi-Arid Regions: Application of Low Impact Development/Green Infrastructure Practices

    Science.gov (United States)

    Yongping, Yuan

    2015-04-01

    Climatic and hydrological characteristics in the arid/semi-arid areas create unique challenges to soil, water and biodiversity conservation. These areas are environmentally sensitive, but very valuable for the ecosystems services they provide to society. Some of these areas are experiencing the fastest urbanization and now face multiple water resource challenges. Low Impact Development (LID)/Green Infrastructure (GI) practices are increasingly popular for reducing stormwater and nonpoint source pollution in many regions around the world. However, streamflow in the arid/semi-arid regions is largely dependent on seasonal, short term, and high intensity rainfall events. LID has not been very common in the arid/semi-arid regions due to a lack of performance evaluation, as well as the perception that LID may not be very useful for regions with little annual precipitation. This study focused on investigating the hydrologic and pollutant removal performance of LID/GI systems in arid/semi-arid climates. Ten types of practices were found in use in the Western/Southwestern U.S.: rainwater harvest systems, detention ponds, retention ponds, bioretention, media filters, porous pavements, vegetated swales/buffer/strips, green roofs, infiltration trenches, and integrated LIDs. This study compared the performance of these practices in terms of their effectiveness at pollutant removal and cost-effectiveness. This analysis provides insight into the future implementation of LID/GI in the arid/semi-arid areas. Key words: LID/GI, arid/semi-arid, effectiveness of pollutant removal, cost-effectiveness analysis

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

    Science.gov (United States)

    Kalluri, Raja Obul Reddy; Gugamsetty, Balakrishnaiah; Kotalo, Rama Gopal; Nagireddy, Siva Kumar Reddy; Tandule, Chakradhar Rao; Thotli, Lokeswara Reddy; Rajuru Ramakrishna, Reddy; Surendranair, Suresh Babu

    2016-10-01

    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 500nm 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 (α380-1020) 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±1.2μgm(-3)) and the lowest in July (1.1±0.2μgm(-3)). The estimated Aerosol Direct Radiative Forcing (ADRF) in the atmosphere is found to be +36.8±1.7Wm(-2), +26.9±0.2Wm(-2), +18.0±0.6Wm(-2) and +18.5±3.1Wm(-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 (36.80Wm(-2)) which contributes more increase in atmospheric heating by ~1K/day. The BC contribution on an average is found to be 64% and is responsible for aerosol atmospheric heating.

  9. Reconstruction of paleohydrology in semi-arid regions for water resources management: Opportunities and challenges

    Science.gov (United States)

    Elshorbagy, Amin; Wagener, Thorsten; Razavi, Saman; Sauchyn, David

    2016-04-01

    Tree-ring based reconstruction of paleohydrology can be a valuable and important means to extend the available hydrological records for several centuries. Such record extension, when properly done, can improve water resources management and planning by making available realistic long records that reflect past short- and long-term hydrometeorological variabilities. This research highlights some of the important, and perhaps unresolved, issues in tree-ring based reconstruction of paleohydrology, especially in semi-arid regions. The relationships between tree growth, as represented by tree-ring chronologies (TRCs), runoff (Q), precipitation (P), and evapotranspiration (ET) are discussed within both statistical and hydrological contexts. The Oldman River Basin (OMRB), Alberta, Canada, is presented as a case study, with TRCs and hydrometeorological data used to demonstrate the relevant issues. Runoff and precipitation data were available through measurements, and actual evapotranspiration was estimated using a lumped conceptual hydrological model developed in this study for the OMRB. Correlation analysis was conducted to explore the relationships between TRCs and each of Q, P, and ET over the entire historical record (globally) as well as locally within the wet and dry subperiods. Global and local correlation strengths and linear relationships appear to be significantly different, particularly affecting tree-ring based inferences about the hydrology and wet and dry episodes from reconstructions made using regression models. This finding is not typically highlighted in the available literature. Reconstruction of paleoQ may also not be as credible as paleoP and paleoET. This is discussed within the context of the watershed storage and release functions. It was also found that a moving average window, of more than one year, of P and ET time series might be necessary for reconstruction of these variables using tree-ring chronologies. This study improves our understanding of

  10. A PROPOSED NEW VEGETATION INDEX, THE TOTAL RATIO VEGETATION INDEX (TRVI, FOR ARID AND SEMI-ARID REGIONS

    Directory of Open Access Journals (Sweden)

    H. Fadaei

    2012-07-01

    Full Text Available Vegetation indices that provide important key to predict amount vegetation in forest such as percentage vegetation cover, aboveground biomass, and leaf-area index. Arid and semi-arid areas are not exempt of this rule. Arid and semi-arid areas of northeast Iran cover about 3.4 million ha and are populated by two main tree species, the broadleaf Pistacia vera (pistachio and the conifer Juniperus excelsa ssp. polycarpos (Persian juniper. Natural stands of pistachio in Iran are not only environmentally important but also genetically essential as seed sources for pistachio production in orchards. We investigated the relationships between tree density and vegetation indices in the arid and semi-arid regions in the northeast of Iran by analysing Advanced Land Observing Satellite (ALOS data PRISM is a panchromatic radiometer with a 2.5 m spatial resolution at nadir, and has one band with a wavelength of 0.52–0.77 μm (JAXA EORC. AVNIR-2 is a visible and near infrared radiometer for observing land and coastal zones with a 10 m spatial resolution at nadir, and has four multispectral bands: blue (0.42–0.50 μm, green (0.52–0.60 μm, red (0.61–0.69 μm, and near infrared (0.76–0.89 μm (JAXA EORC. In this study, we estimated various vegetation indices using maximum filtering algorithm (5×5 and examined. This study carried out of juniper forests and natural pistachio stand using Advanced Land Observing Satellite (ALOS and field inventories. Have been compared linear regression model of vegetation indices and proposed new vegetation index for arid and semi-arid regions. Also, we estimated the densities of juniper forests and natural pistachio stands using remote sensing to help in the sustainable management and production of pistachio in Iran. We present a new vegetation index for arid and semi-arid regions with sparse forest cover, the Total Ratio Vegetation Index (TRVI, and we investigate the relationship of the new index to tree density by

  11. Modeling the Surface Water-Groundwater Interaction in Arid and Semi-Arid Regions Impacted by Agricultural Activities

    Science.gov (United States)

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

    2013-12-01

    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.

  12. Impacts of urbanization on nitrogen cycling and aerosol, surface and groundwater transport in semi-arid regions

    Science.gov (United States)

    Lohse, K. A.; Gallo, E.; Carlson, M.; Riha, K. M.; Brooks, P. D.; McIntosh, J. C.; Sorooshian, A.; Michalski, G. M.; Meixner, T.

    2011-12-01

    Semi-arid regions are experiencing disproportionate increases in human population and land transformation worldwide, taxing limited water resources and altering nitrogen (N) biogeochemistry. How the redistribution of water and N by urbanization affects semi-arid ecosystems and downstream water quality (e.g. drinking water) is unclear. Understanding these interactions and their feedbacks will be critical for developing science-based management strategies to sustain these limited resources. This is especially true in the US where some of the fastest growing urban areas are in semi-arid ecosystems, where N and water cycles are accelerated, and intimately coupled, and where runoff from urban ecosystems is actively managed to augment a limited water supply to the growing human population. Here we synthesize several ongoing studies from the Tucson Basin in Arizona and examine how increasing urban land cover is altering rainfall-runoff relationships, groundwater recharge, water quality, and long range transport of atmospheric N. Studies across 5 catchments varying in impervious land cover showed that only the least impervious catchment responded to antecedent moisture conditions while hydrologic responses were not statistically related to antecedent rainfall conditions at more impervious sites. Regression models indicated that rainfall depth, imperviousness, and their combined effect control discharge and runoff ratios (p < 0.01, r2 = 0.91 and 0.75, respectively). In contrast, runoff quality was not predictably related to imperviousness or catchment size. Rather, rainfall depth and duration, time since antecedent rainfall, and stream channel characteristics and infrastructure controlled runoff chemistry. Groundwater studies showed nonpoint source contamination of CFCs and associated nitrate in areas of rapid recharge along ephemeral channels. Aerosol measurements indicate that both long-range transport of N and N emissions from Tucson are being transported and deposited

  13. Different responses of MODIS-derived NDVI to root-zone soil moisture in semi-arid and humid regions

    Science.gov (United States)

    Wang, Xianwei; Xie, Hongjie; Guan, Huade; Zhou, Xiaobing

    2007-06-01

    SummarySurface representation of the root-zone soil moisture is investigated so that feasibility of using optical remote sensing techniques to indirectly map root-zone soil moisture is assessed. Specifically, covariation of root-zone soil moisture with the normalized difference of vegetation index (NDVI) from Moderate Resolution Imaging Spectroradiometer (MODIS) is studied at three sites (New Mexico, Arizona, and Texas) selected from the Soil Climate Analysis Network (SCAN). The three sites represent two types of vegetation (shrub and grass) and two types of climate conditions: semi-arid (New Mexico and Arizona) and humid (Texas). Collocated deseasonalized time series of soil moistures at five depths (5 cm, 10 cm, 20 cm, 50 cm, and 100 cm) and NDVI (8-day composite in 250 m resolution) during the period of February 2000 through April 2004 were used for correlation analysis. Similar analysis was also conducted for the raw time series for comparison purposes. The linear regression of both the deseasonalized time series and the raw time series was used to estimate root-zone soil moisture. Results show that (1) the deseasonalized time series results in consistent and significant correlation (0.46-0.55) between NDVI and root-zone soil moisture at the three sites; (2) vegetation (NDVI) at the humid site needs longer time (10 days) to respond to soil moisture change than that at the semi-arid sites (5 days or less); (3) the time-series of root-zone soil moisture estimated by a linear regression model based on deseasonalized time series accounts for 42-71% of the observed soil moisture variations for the three sites; and (4) in the semi-arid region, root-zone soil moisture of shrub-vegetated area can be better estimated using NDVI than that of grass-vegetated area.

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

    Energy Technology Data Exchange (ETDEWEB)

    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: krgverma@yahoo.com [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)

    2016-10-01

    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

  15. Analysis of Vegetation Behavior in a North African Semi-Arid Region, Using SPOT-VEGETATION NDVI Data

    Directory of Open Access Journals (Sweden)

    Abdelghani Chehbouni

    2011-11-01

    Full Text Available The analysis of vegetation dynamics is essential in semi-arid regions, in particular because of the frequent occurrence of long periods of drought. In this paper, multi-temporal series of the Normalized Difference of Vegetation Index (NDVI, derived from SPOT-VEGETATION satellite data between September 1998 and June 2010, were used to analyze the vegetation dynamics over the semi-arid central region of Tunisia. A study of the persistence of three types of vegetation (pastures, annual agriculture and olive trees is proposed using fractal analysis, in order to gain insight into the stability/instability of vegetation dynamics. In order to estimate the state of vegetation cover stress, we propose evaluating the properties of an index referred to as the Vegetation Anomaly Index (VAI. A positive VAI indicates high vegetation dynamics, whereas a negative VAI indicates the presence of vegetation stress. The VAI is tested for the above three types of vegetation, during the study period from 1998 to 2010, and is compared with other drought indices. The VAI is found to be strongly correlated with precipitation.

  16. Hierarchical distance-based fuzzy approach to evaluate urban water supply systems in a semi-arid region.

    Science.gov (United States)

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

    2015-01-01

    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.

  17. Biological spectrum and dispersal syndromes in an area of the semi-arid region of north-eastern Brazil

    Directory of Open Access Journals (Sweden)

    Elimar Alves de Lima

    2015-03-01

    Full Text Available The biological spectrum and diaspores dispersal syndromes of the species recorded in a stretch of vegetation in a semi-arid region within the Cariri Environment Protection Area, Boa Vista, Paraíba State (northeast Brazil, are described. Collections were made from fertile specimens, preferentially bearing fruit, over a 15-month period. Life forms and syndromes were determined by field observations using specialized literature. One hundred and sixty-six species, distributed into 123 genera and 41 families, were reported. Abiotic syndromes (autochory and anemochory represented 69.7% of all syndromes identified, whilst 30.3% of the species were classified as zoochory. In the life form spectrum therophytes represented 27.7% of species, followed by small- and medium-sized phanerophytes (23.5% and chamaephytes (22.3%. The occurrence of hemicryptophytes (9%, cryptophytes (0.6% and species that could not be classified according to their life forms was also recorded (16.9%. Results showed that the biological spectrum and the dispersal syndromes are highly relevant to understand the structure and function of this phytocenose, with subsidies for the development of other studies in the semi-arid areas of northeastern Brazil.

  18. Resistência natural de nove madeiras do semi-árido brasileiro a fungos xilófagos em condições de laboratório Natural resistance of nine woods of Brazilian semi-arid region to wood-destroying fungi under laboratory conditions

    Directory of Open Access Journals (Sweden)

    Juarez Benigno Paes

    2004-04-01

    Full Text Available Objetivou-se avaliar a resistência natural de nove madeiras do semi-árido brasileiro a fungos xilófagos, em condições de laboratório. As madeiras estudadas foram a algaroba (Prosopis juliflora, o angico (Anadenanthera macrocarpa, a aroeira (Myracrodruon urundeuva, a braúna (Schinopsis brasiliensis, a cássia (Senna siamea, a craibeira (Tabebuia aurea, o cumaru (Amburana cearensis, o ipê (Tabebuia impetiginosa e o pereiro (Aspidosperma pyrifolium. De cada espécie foram retirados corpos-de-prova de 2,54 x 2,00 x 1,00 cm, com a maior dimensão na direção das fibras, em quatro posições na direção medula-casca. As amostras foram submetidas, por 14 semanas, à ação dos fungos Postia placenta e Neolentinus lepideus. A resistência natural, com exceção da algaroba e do angico (P. placenta, da craibeira (N. lepideus e da cássia (P. placenta e N. lepideus, foi afetada pela posição na direção medula-casca, sem estar relacionada à densidade das madeiras ensaiadas. A madeira de ipê e a madeira de cerne da aroeira e braúna foram as mais resistentes aos fungos testados. As diferenças entre a resistência natural, exceto para a aroeira e braúna, não estavam associadas à concentração de extrativos solúveis em água quente.The objective of this research was to evaluate the natural resistance of nine semi arid region Brazilian woods to wood-destroying fungi under laboratory conditions. The studied woods were the Prosopis juliflora, Anadenanthera macrocarpa, Myracrodruon urundeuva, Schinopsis brasiliensis, Senna siamea, Tabebuia aurea, Amburana cearensis, Tabebuia impetiginosa and Aspidosperma pyrifolium. Test samples measuring 2.54 x 2.00 x 1.00 cm, with the largest measure taken fiber-wise were obtained from four pith-to-bark positions. The samples were submitted to action of the Postia placenta and Neolentinus lepideus fungi for 14 weeks. Species resistance, with exception of those of Prosopis juliflora and Anadenanthera

  19. Resistência natural de nove madeiras do semiárido brasileiro a fungos xilófagos em simulares de campo Natural resistance of nine woods from the Brazilian semi-arid region to wood-destroying fungi in field simulators

    Directory of Open Access Journals (Sweden)

    Juarez Benigno Paes

    2009-06-01

    Full Text Available Os objetivos desta pesquisa foram avaliar a resistência de nove madeiras de ocorrência no semiárido brasileiro a fungos xilófagos em simuladores de campo e relacionar a resistência natural com a densidade e teor de substâncias extraídas em água quente. As madeiras estudadas foram algaroba (Prosopis juliflora, angico-vermelho (Anadenanthera colubrina var. cebil, aroeira (Myracrodruon urundeuva, braúna (Schinopsis brasiliensis, cássia (Senna siamea, craibeira (Tabebuia aurea, cumaru (Amburana cearensis, pau-d'arco (Tabebuia impetiginosa e pereiro (Aspidosperma pyrifolium. De cada espécie foram retirados corpos-de-prova de 0,5 x 1,5 x 15,0 cm, com a maior dimensão na direção das fibras, em quatro posições na direção medula-casca do tronco. As amostras permaneceram por 180 dias sob ação da microflora natural existente em três tipos de solos: de floresta, de uso agrícola e com gramíneas. Em todas as madeiras ensaiadas, a resistência ao apodrecimento foi afetada pela posição na direção medula-casca. Apenas na aroeira a resistência da madeira esteve associada à sua densidade e à quantidade de extrativos solúveis em água quente. A resistência das madeiras de algaroba, angico, craibeira e pau-d'arco não esteve associada à densidade nem ao teor de extrativos. O alburno foi a posição mais atacada em todos os solos analisados. Entre os solos testados, o de uso agrícola apresentou menos atividade biológica, deteriorando menos as madeiras testadas.The objectives of this research were to evaluate the natural resistance of nine woods from the Brazilian semi-arid region to fungi under field simulator condition and to correlate the wood natural resistance with the wood density and the content of extractives soluble in hot water. The studied woods were Prosopis juliflora, Anadenanthera colubrina var. cebil, Myracrodruon urundeuva, Schinopsis brasiliensis, Senna siamea, Tabebuia aurea, Amburana cearensis, Tabebuia

  20. Regional validity of the parameters of a distributed runoff-erosion model in the semi-arid region of Brazil

    Institute of Scientific and Technical Information of China (English)

    SRINIVASAN Vajapeyam Srirangachar; PAIVA Fernanda Maria de Lima

    2009-01-01

    The present paper examines the validity of the application of a distributed rainfall-runoff-erosion model on a regional basis in a semi-arid region of Brazil.The model tested is known as WESP (Water Erosion Simulation Program) developed by Lopes (1987).The model simulates the hydrograph and the sedi-ment graph for individual events and thus, the model when properly calibrated can serve as a predic-tive tool for runoff and soil erosion on an individual or a continuous basis.The possibility of the exis-tence of regionally applicable values for the parameters of the model WESP would be very interesting from the point of view of predictability of runoff and soil erosion from ungauged basins in the region.For this purpose, data collected in several experimental units in the experimental basin of Sume as well as in the experimental basin of Sao Joao de Cariri have been used.The model was calibrated and validated in each of the experimental units (consisting of erosion plots and micro-basins) and the av-erage value from all of the units for each of the parameters was considered to be the regional value.With these average values, all the events in all the experimental units were simulated.The results show that the runoff and erosion values simulated with this single parameter set were very good in all the units, being well within the acceptable deviations.

  1. Regional validity of the parameters of a distributed runoff-erosion model in the semi-arid region of Brazil

    Institute of Scientific and Technical Information of China (English)

    SRINIVASAN; Vajapeyam; Srirangachar; PAIVA; Fernanda; Maria; de; Lima

    2009-01-01

    The present paper examines the validity of the application of a distributed rainfall-runoff-erosion model on a regional basis in a semi-arid region of Brazil. The model tested is known as WESP (Water Erosion Simulation Program) developed by Lopes (1987). The model simulates the hydrograph and the sediment graph for individual events and thus, the model when properly calibrated can serve as a predictive tool for runoff and soil erosion on an individual or a continuous basis. The possibility of the existence of regionally applicable values for the parameters of the model WESP would be very interesting from the point of view of predictability of runoff and soil erosion from ungauged basins in the region. For this purpose, data collected in several experimental units in the experimental basin of Sumé as well as in the experimental basin of So Joo de Cariri have been used. The model was calibrated and validated in each of the experimental units (consisting of erosion plots and micro-basins) and the average value from all of the units for each of the parameters was considered to be the regional value. With these average values, all the events in all the experimental units were simulated. The results show that the runoff and erosion values simulated with this single parameter set were very good in all the units, being well within the acceptable deviations.

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

    Directory of Open Access Journals (Sweden)

    Yuanwei Qin

    2016-11-01

    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

  3. Assessment of desertification risk in semi-arid Mediterranean environments: the case study of Apulia region (Southern Italy)

    Science.gov (United States)

    Ladisa, Gaetano; Todorovic, Mladen; Trisorio Liuzzi, Giuliana

    2010-05-01

    This work focuses on the risk assessment of the areas threatened with desertification in the semi-arid Mediterranean environments. The presented approach uses as a reference the ESAs model (Environmental Sensitive Areas to Desertification; Kosmas et al., 1999) which is modified through a set of new indicators which take into account the region-specific environmental characteristics as well as identifiable parameters relevant for planning control measures. These supplementary indicators, comprehending socio-economic and environmental factors, are integrated in the ESAs model and, by using a GIS, applied to Apulia region (Southern Italy). This area represents a typical Mediterranean landscape affected by land degradation and desertification risks. The analyses include the elaboration of the whole set of indices on both the regional and the administrative scales which constitute the principal territorial units for the management of natural resources. The results have demonstrated that the introduction of the new indices has improved substantially the overall evaluation of the desertification risk in the Apulia region. The proposed approach permits not only the identification and refinement of different degrees of sensibility of an area to land degradation, but also the analyses of the factors affecting desertification and their evaluation in terms of spatial and temporal distribution. Moreover, the presented method is conceptually very simple and easy to implement from local to regional and national scale, and can be proposed as a methodology for the definition of priorities in adoption of strategies to mitigate desertification in the semi-arid Mediterranean environments. Key words: desertification risk, sensitivity areas, Apulia region, Mediterranean environment.

  4. Characterization of Pseudomonas Species Isolated from the Rhizosphere of Plants Grown in Serozem Soil, Semi-Arid Region of Uzbekistan

    Directory of Open Access Journals (Sweden)

    Dilfuza Egamberdiyeva

    2005-01-01

    Full Text Available Collections of native Pseudomonas spp. are kept at the NCAM of Uzbekistan. Some of those organisms were isolated from the rhizosphere of cotton, wheat, corn, melon, alfalfa, and tomato grown in field locations within a semi-arid region of Uzbekistan. Strains used for this study were Pseudomonas alcaligenes, P. aurantiaca, P. aureofaciens, P. denitrificans, P. mendocina, P. rathonis, and P. stutzeri. Some of the pseudomonads have been characterized in this report. These strains produced enzymes, phytohormone auxin (IAA, and were antagonist against plant pathogenic fungi in in vitro experiments. Most of the strains were salt tolerant and temperature resistant. Some of the Pseudomonas spp. isolated in this study have been found to increase the growth of wheat, corn, and tomato in pot experiments.

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

    Institute of Scientific and Technical Information of China (English)

    WANG Hesong; JIA Gensuo

    2012-01-01

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

  6. A review of groundwater recharge estimation in humid and semi-arid African regions

    Science.gov (United States)

    Chung, Il-Moon; Kim, Nam Won

    2016-04-01

    For the review of African recharge estimation, the distinct methods such as the geochemical approach, a method using groundwater level data, the streamflow method, and the water balance methods were first outlined. The major challenge of an African recharge study is the lack of basic data. Thus, this work suggests how to deal with this limitation and from future perspective using recently developed technologies such as RS, GIS, etc. With the rapid growth of information technology, more and more data, in terms of both volume and variety, are expected to be made available on the internet in the near future. RS technology has a great potential to revolutionize the groundwater development and management in the future by providing unique and completely new hydrological and hydrogeological data. However, at present, the RS data should be considered along with the conventional field data. In spite of the weaknesses of water balance methods in semi-arid areas, recently developed water balance methods combined with GIS technology are powerful tools for estimating groundwater re-charge, when spatial-temporal variability of components in water balance is taken into account (Lerner et al., 1990; De Vries and Simmers, 2002; Eilers et al., 2007).When enough data sets are available, integrated surface-groundwater modeling is recommended for more accurate estimation of groundwater recharge and discharge. Acknowledgements This work was supported by a grant(14RDRP-B076275-01-000000) from Infrastructure and transportation technology promotion research Program funded by the Ministry of Land, Infrastructure and Transport of Korean government.

  7. Remote sensing-based vegetation indices for monitoring vegetation change in the semi-arid region of Sudan

    Science.gov (United States)

    R. A., Majdaldin; Osunmadewa, B. A.; Csaplovics, E.; Aralova, D.

    2016-10-01

    Land degradation, a phenomenon referring to (drought) in arid, semi-arid and dry sub-humid regions as a result of climatic variations and anthropogenic activities most especially in the semi-arid lands of Sudan, where vast majority of the rural population depend solely on agriculture and pasture for their daily livelihood, the ecological pattern had been greatly influenced thereby leading to loss of vegetation cover coupled with climatic variability and replacement of the natural tree composition with invasive mesquite species. The principal aim of this study is to quantitatively examine the vigour of vegetation in Sudan through different vegetation indices. The assessment was done based on indicators such as soil adjusted vegetation index (SAVI). Cloud free multi-spectral remotely sensed data from LANDSAT imagery for the dry season periods of 1984 and 2009 were used in this study. Results of this study shows conversion of vegetation to other land use type. In general, an increase in area covered by vegetation was observed from the NDVI results of 2009 which is a contrast of that of 1984. The results of the vegetation indices for NDVI in 1984 (vegetated area) showed that about 21% was covered by vegetation while 49% of the area were covered with vegetation in 2009. Similar increase in vegetated area were observed from the result of SAVI. The decrease in vegetation observed in 1984 is as a result of extensive drought period which affects vegetation productivity thereby accelerating expansion of bare surfaces and sand accumulation. Although, increase in vegetated area were observed from the result of this study, this increase has a negative impact as the natural vegetation are degraded due to human induced activities which gradually led to the replacement of the natural vegetation with invasive tree species. The results of the study shows that NDVI perform better than by SAVI.

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

    Directory of Open Access Journals (Sweden)

    Aloah J Pope

    2015-08-01

    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.

  9. [Water and soil conservation function of typical plantation forest ecosystems in semi-arid region of Western Liaoning Province].

    Science.gov (United States)

    Jiang, Ping; Guo, Fang; Luo, Yue-Chu; Wei, Jing; Sun, Xiao-Wei; Wu, Gang

    2007-12-01

    From the aspects of surface runoff and soil erosion, this paper quantitatively studied the water and soil conservation function of five plantation forest ecosystems in semi-arid region of Western Liaoning Province. The results showed that various types of test plantation forest ecosystems were all able to reduce surface runoff and soil erosion effectively. In June - September, the monthly mean surface runoff coefficient of Pinus tabulaeformis forest ecosystem, P. tabulaeformis - Hippophae rhamnoides forest ecosystem, H. rhamnoides forest ecosystem, P. simonii forest ecosystem, and P. simonii - H. rhamnoides forest ecosystem was 10.1%, 6.5%, 2.3%, 8.6% and 5.3% of that of barren hill, respectively, and the soil erosion quantity was 2.65%, 0.96%, 0.15%, 2.32% and 0.69% of that of barren hill, respectively. Among the five forest ecosystems, H. rhamnoides forest ecosystem had the least surface runoff and soil erosion, being the best in water and soil conservation function.

  10. 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

    2011-01-01

    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.

  11. Effects of adding water on seasonal variation of soil nitrogen availability under sandy grasslands in semi-arid region

    Institute of Scientific and Technical Information of China (English)

    HUANG Xiao-xing; YU Zhan-yuan; QIAN Wei; XU Da-yong; AI Gui-yan

    2007-01-01

    Water is usally thought of a limiting factor for the restoration of semi-arid ecosystem. In the growing season of 2006, a study was conducted to determine the effects of modeling precipitation on seasonal patterns in concentrations of soil-available nitrogen and to describe the seasonal patterns in soil nitrogen availability and seasonal variation in the rates of net nitrogen mineralization of topsoil at Daqinggou ecological station in Keerqin sand lands, Inner Mongolia Autonomous Region, China. Manipulation of water (80 mm) was designed to be added to experiment plots of sandy grasslands in dry season. Water addition (W) treatment and control (CK) treatment were separately taken in six replications and randomly assigned in 12 plots (4 m×4 m for each) with 2-m buffers betweens. Results showed that the content of soil inorganic nitrogen and net nitrogen mineralization rate were not affected by adding water in sandy grassland of Keerqin sand lands. Net nitrogen mineralization rates ranged from 0.5 μg·g-1·month-1 to 4 μg·g-1·month-1. The highest values of soil inorganic nitrogen and net nitrogen mineralization occurred on October 15 in control plots. The seasonal changes of soil inorganic nitrogen contents exhibited "V" shape pattern that was related to seasonal patterns of soil ammonium-N (ascending trend) and nitrate-N transformation (descending trend).

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

    Science.gov (United States)

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

    2015-02-01

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

  13. Regional differences in the surface temperature of Naked Neck laying hens in a semi-arid environment

    Science.gov (United States)

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

    2013-05-01

    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.

  14. Applicability of the Thermal Infrared Spectral Region for the Prediction of Soil Properties Across Semi-Arid Agricultural Landscapes

    Directory of Open Access Journals (Sweden)

    Sabine Chabrillat

    2012-10-01

    Full Text Available In this study we tested the feasibility of the thermal infrared (TIR wavelength region (within the atmospheric window between 8 and 11.5 μm together with the traditional solar reflective wavelengths for quantifying soil properties for coarse-textured soils from the Australian wheat belt region. These soils have very narrow ranges of texture and organic carbon contents. Soil surface spectral signatures were acquired in the laboratory, using a directional emissivity spectrometer (μFTIR in the TIR, as well as a bidirectional reflectance spectrometer (ASD FieldSpec for the solar reflective wavelengths (0.4–2.5 μm. Soil properties were predicted using multivariate analysis techniques (partial least square regression. The spectra were resampled to operational imaging spectroscopy sensor characteristics (HyMAP and TASI-600. To assess the relevance of specific wavelength regions in the prediction, the drivers of the PLS models were interpreted with respect to the spectral characteristics of the soils’ chemical and physical composition. The study revealed the potential of the TIR (for clay: R2 = 0.93, RMSEP = 0.66% and for sand: R2 = 0.93, RMSEP = 0.82% and its combination with the solar reflective region (for organic carbon: R2 = 0.95, RMSEP = 0.04% for retrieving soil properties in typical soils of semi-arid regions. The models’ drivers confirmed the opto-physical base of most of the soils’ constituents (clay minerals, silicates, iron oxides, and emphasizes the TIR’s advantage for soils with compositions dominated by quartz and kaolinite.

  15. Validation of MODIS and Deep Blue aerosol optical depth retrievals in an arid/semi-arid region of northwest China

    Institute of Scientific and Technical Information of China (English)

    Xia Li; Xiangao Xia; Shengli Wang; Jietai Mao; Yan Liu

    2012-01-01

    The global aerosol optical depth (AOD or τ) has been retrieved using the Dark Target algorithm (the C004 and C005 products) and the Deep Blue algorithm (DB product).Few validations have thus far been performed in arid/semi-arid regions,especially in northwest China.The ground-based remote sensing of AOD from sun photometers at four sites in Xinjiang during the years 2002-2003 is used to validate aerosol products,including C004,C005 and DB of the Moderate Resolution Imaging Spectroradiometer (MODIS).The results show substantial improvement in the C005 aerosol product over the C004 product.The average correlation coefficient of regression with ground measurements increased from 0.59 to 0.69,and the average offset decreased from 0.28 to 0.13.The slopes of the linear regressions tended to be close to unity.The percentage of AODs falling within the retrieval errors of 30% (or △τ =±0.1 ± 0.2τ)increased from 16.1% to 45.6%.The best retrievals are obtained over an oasis region,whereas the worst are obtained over urban areas.Both the MODIS C004 and C005 products overestimate AOD,which is likely related to improper assumptions of the aerosol model and of the estimation of surface reflectance.An encouraging result has been derived with regard to validation of the DB AOD.Overall,the average offset,slope and correlation coefficient of regression with sun-photometer measurements are -0.04,0.88 and 0.85,respectively.Approximately 73% of the DB AOD retrievals fall within the expected error of 30%.Underestimation of the AOD by the DB products is observed.The aerosol model and estimations of surface reflectance in this region require further improvements.

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

    KAUST Repository

    Schillaci, Calogero

    2016-10-29

    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.

  17. The International Workshop on Environmental Changes and Sustainable Development in Arid and Semi-arid Regions

    Institute of Scientific and Technical Information of China (English)

    Xiaoping Yang; Arthur Conacher

    2007-01-01

    @@ Arid regions,dominated by deserts,are characterized by a severe shortage of moisture,and a lack of perennial and integrated systems of drainage.Distributed over a very large range of temperatures,from the very hot to the very cold zones,arid regions cover about one third of the world's land surface and occur in every continent,including Antarctica.

  18. Plant species diversity of wetland ecosystem in an arid and semi-arid region in northwest China

    Institute of Scientific and Technical Information of China (English)

    LI Rui; LIU Yunfang; ZHANG Kebin

    2007-01-01

    In order to study the changes of plant species diversity along the biotope gradient and its influencing factors in a wetland-add grassland ecosystem in the add and semi-arid regions of northwest China,four transect lines were set along the biotope gradient in four directions:east,northeast,west and northwest,and altogether 123 sample plots were investigated on species composition,density,foliage cover,height and biomass (calculated in fresh weight).The whole study area was divided into the Wetland zone,the ecotone and the arid grassland zone in terms of habitat characteristics and vegetation types.In this paper,we analyzed and compared the species diversity in the ecotone of a wetland-dry grassland ecosystem in Yanchi County,Ningxia Hui Autonomous Region,with the help of biodiversity software BioDiversity Pro and statistical software Microcal Origin,as well as the combined measurement of species diversity indices.The results revealed distinct differences between those three vegetation zones along each transect line.The ecotone had the highest richness indices (R) and comprehensive diversity indices (Y),reflecting the edge effect.The greatest evenness indices (E) were found in the add grassland zones.This result agreed with the phenomenon of desertification reversion,vegetation restoration and dominant communities' formation.As for the four transect lines,the east and the northeast scored higher in each diversity index than the others due to less human disturbance,gentler topography uplift and more intercepted materials and energies.The highest Simpson index value was found in the northeast transect line,which was 39.9% higher than the lowest in the Northwest.

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

    Directory of Open Access Journals (Sweden)

    Tana P. MEWADA

    2015-09-01

    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.

  20. Myxomycetes associated with Cactaceae in sub-humid (agreste and semi-arid (sertão regions of Pernambuco, Brazil

    Directory of Open Access Journals (Sweden)

    Inaldo do Nascimento Ferreira

    2011-06-01

    Full Text Available Studies that indicate the presence of Myxomycetes in arid and semi-arid regions of the planet have revealed new taxons and high species diversity. In those environments, the Myxomycetes occupy special microhabitats like those offered by succulent plants. Aiming to expand the knowledge of species that occur in semi-arid environments we investigated the occurrence of Myxomycetes on Cereus jamacaru (mandacaru, Melocactus bahiensis (coroa de frade, Opuntia ficus-indica (palma forrageira and Pilocereus gounellei (xique-xique – cacti that compose the natural landscape of the sub-humid (agreste and semi-arid (sertão regions of Pernambuco, Brazil. We obtained 158 specimens of Myxomycetes (106 field collections; 52 in moist chamber cultures, representing 16 species distributed in nine genera, with high taxonomic diversity (S/G= 0.63-1.5. All of the identified species are new records for the municipalities studied. Comatricha pulchella, Didymium nigripes and Physarum bogoriense are mentioned for the first time in Caatinga areas in the state of Pernambuco, and Didymium squamulosum and Physarum echinosporum are new records for this biome. Physarum compressum and Badhamia melanospora were the most abundant and frequent species, characterized as constant in the studied myxobiota.

  1. Sources and Pathways of Nutrients in the Semi-Arid Region of Beijing–Tianjin, China

    Science.gov (United States)

    2012-01-01

    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

  2. Effects of different agricultural managements in soil microbial community structure in a semi-arid Mediterranean region.

    Science.gov (United States)

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

    2013-04-01

    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).

  3. Spatial pattern of a plant community in a wetland ecosystem in a semi-arid region in northwestern China

    Institute of Scientific and Technical Information of China (English)

    Kebin ZHANG; Rui LI; Yunfang LIU; Baitian WANG; Xiaohui YANG; Ruiping HOU

    2008-01-01

    The spatial distribution characteristics of plant communities in a wetland-dry grassland ecosystem in arid and semi-arid regions in northwestern China and the main factors affecting the distribution pattern were studied. The Siertan wetland in the Haba Lake Nature Reserve was the study area. Four transect lines, each about 1 km long, were set up in the growing season along the biotope gradient in four directions: east, northeast, west and northwest. Attributes measured include frequency of occurrence, height, density, coverage, biomass and envir-onmental soil factors. The data were analyzed using a two-way indicative species analysis (TWINSPAN), detrended correspondence analysis (DCA) and Spear-man correlation coefficients. On this basis, the vegetation in the Siertan wetland was classified into three types and 14 associations. The first vegetation type was halophytic marsh vegetation, mainly distributed in the wetland zone. This type largely contains halophyte and hygric plants and its representative association is Phragmites communis + Kalidiumfoliatum. The second type was meadow vegeta-tion, distributed in the ecotone. The meadow vegetation species are mainly mesophytic and their representative association is Nitraria tangutorum+ Pennisetum flacci-dum. The third vegetation type is grassland vegetation, which mainly consists of mesophytic and xerophytes, dis-tributed in the arid grassland zone. The representative association of the third vegetation type is the association of Anaeurolepidium secalium + Saussurea runcinata. Correlation analysis between the axes of DCA and envir-onmental soil factors shows that soil moisture content, organic matter, soil salt content and total nitrogen are the main environmental factors affecting the pattern of vegetation distribution along the biotope gradients from wetland to arid grassland. Other factors affecting the vegetation are microtopography and grazing pressure. Additionally, we have reported modifications and

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

    Directory of Open Access Journals (Sweden)

    Qidong Yang

    Full Text Available 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.

  5. JOJOBA: an oil plant for arid or semi-arid regions

    Energy Technology Data Exchange (ETDEWEB)

    Marull, J.E.

    1978-01-01

    Jojoba (Simmondsia chinesis) grows in regions with a rainfall of 250 to 450 mm, producing 4.5 kg seeds/tree after 36 months and attaining an average production of 13.8 kg seeds/tree when full grown. Productivity can be maintained for up to 100 years. Planting density is about 1600 plants/ha, at distances of 1.50 x 3.00 m. The seeds contain 50% edible oil, and the press-cake 35% proteins. The characteristics of the oil are listed.

  6. Jojoba, an oil plant for arid or semi-arid regions

    Energy Technology Data Exchange (ETDEWEB)

    Marull, J.E.

    1978-01-01

    Jojoba (Simmondsia chinensis) grows in regions with a rainfall of 250-450 mm, producing 4.5 kg seeds/tree after 36 months and attaining an average production of 13.8 kg seeds/tree when full grown. Productivity can be maintained for up to 100 years. Planting density is about 1600 plants/ha, at distances of 1.50 x 3.00 m. The seeds contain 50% edible oil, and the press-cake 35% proteins. The characteristics of the oil are listed.

  7. Impact of sublimation losses in the mass balance of glaciers in semi-arid mountain regions

    Science.gov (United States)

    Ayala, Alvaro; Pellicciotti, Francesca; Burlando, Paolo; MacDonell, Shelley; McPhee, James

    2016-04-01

    Glaciers in semiarid mountain regions may lose an important part of their winter snow accumulation through sublimation processes that are enhanced by the high-elevation, intense radiation and dry atmosphere of these environments. As glaciers in these regions secure freshwater resources to lower valleys during summer and drought periods, it is important to advance in a detailed quantification of their sublimation losses. However, logistical concerns and complex meteorological features make the measuring and modelling of glacier mass balances a difficult task. In this study, we estimated the spring-summer mass balances of Tapado and Juncal Norte glaciers in the semiarid Andes of north-central Chile by running a distributed energy balance model that accounts for melt, refreezing and sublimation from the surface and blowing snow. Meteorological input data were available from on-glacier Automatic Weather Stations (AWS) that were installed during the ablation season of years 2005-06, 2008-09, 2013-14 and 2014-15. Snow pits, ablation stakes and a time-lapse camera that provided surface albedo were also available. Distributed air temperature and wind speed were dynamically downscaled from NASA MERRA reanalysis using the software WINDSIM and validated against the data from the AWSs. The rest of the meteorological variables were distributed using statistical relations with air temperature derived from the AWSs data. Initial snow conditions were estimated using satellite images and distributed manual snow depth measurements. Preliminary results show that total ablation diminishes with elevation and that, during the early ablation season (October-November), melt is the main ablation component below 4500 m with sublimation dominating the ablation above this elevation. Above 4500 m an important fraction of meltwater refreezes during night. As the ablation season advances (December-February), melt extends to higher elevations, refreezing plays a smaller role and sublimation is

  8. Rainwater Management Model Development for Agriculture in the Savu Island Semi-Arid Region

    Directory of Open Access Journals (Sweden)

    Susilawati C.L.

    2012-01-01

    Full Text Available Savu Island is a semiarid region with few rainfalls. The meager annual rainfall of about 1,000-1,500 mm that lasts for three to five months tends to cause draught. To cope with this situation, the Author tries to develop a rainwater management model located in Daieko village. This model constitutes an infrastructure that consists of check dam series which are constructed by simulating a computerized model of decision supporting system called “Rainwater Management for Agriculture Decision Support System (RMA-DSS model” in the research location of Daieko village. Employing a simulated RMA-DSS model; the locations for check-dam series, and dug-wells can be determined, the size of potential irrigable lands can be determined based on water balance analysis of water samples taken from simulated check dams and inundated lands. Through this model the sufficiency of water supply for agricultural purposes and the land size for cultivation area can be predicted with a high degree of certainty.

  9. Root density of cherry trees grafted on prunus mahaleb in a semi-arid region

    Science.gov (United States)

    Paltineanu, Cristian; Septar, Leinar; Gavat, Corina; Chitu, Emil; Oprita, Alexandru; Moale, Cristina; Lamureanu, Gheorghe; Vrinceanu, Andrei

    2016-07-01

    Root density was investigated using the trench method in a cherry (Prunus avium grafted on Prunus mahaleb) orchard with clean cultivation in inter-rows and in-row. Trenches of 1 m width and 1.2 m depth were dug up between neighbouring trees. The objectives of the paper were to clarify the spatial distribution of root density of cherry trees under the soil and climate conditions of the region to expand knowledge of optimum planting distance and orchard management for a broad area of chernozems. Some soil physical properties were significantly worsened in inter-rows versus in-row, mainly due to soil compaction, and there were higher root density values in in-row versus inter-rows. Root density decreased more intensely with soil depth than with distance from trees. The pattern of root density suggests that the cherry tree density and fruit yield could be increased. However, other factors concerning orchard management and fruit yield should also be considered. The results obtained have a potential impact to improve irrigation and fertilizer application by various methods, considering the soil depth and distance from trees to wet soil, in accordance with root development.

  10. Mashhad Wise Water Forum: a path to sustainable water resources management in a semi-arid region of Iran

    Science.gov (United States)

    Tabatabaee, Seyyed Alireza; Neyshaboori, Shahnaz; Basirat, Ali; Tavakoli Aminiyan, Samaneh; Mirbehrooziyan, Ahmad; Sakhdari, Hossein; Shafiei, Mojtaba; Davary, Kamran

    2016-04-01

    Water is key to sustainable development especially in semi-arid regions in which the main source of water provision is groundwater. Water has value from a social, economic and environmental perspective and is required to be managed within a sound, integrated socio-economic and environmental framework. Mashhad, the second big city in Iran, has been faced with rapid growth rates of population and economic activities. The groundwater in Mashhad basin has been overexploited to meet the increasing trend of water demand during the past 20 years. Consequently, the region has faced with water scarcity and water quality problems which originates from inefficient use and poor management. To tackle the water issue on a durable basis, within the economic, ecological, and political constraints (i.e. the integrated water resources management, IWRM concept), a Non-Governmental Organization (NGO), named as Mashhad Wise Water Forum (MWWF), has been established in 2013 that encompasses contribution of experts from academia, industry, and governmental policy-makers. The MWWF considers the UN-Water IWRM spiral conceptual model (which contains four stages: Recognizing and identifying; Conceptualizing; Coordinating and planning; Implementing, Monitoring and Evaluating) by implicating participatory water management (water users' involvement) methods in Mashhad basin. Furthermore, the MWWF has planned to look at all dimensions of water crisis (i.e. physical, economic, policy and institutional) particularly institutional dimension by gathering all stockholders, beneficiaries and experts in different parts of water policy making in Mashhad basin. The MWWF vision for Mashhad basin is achieving to sustainable equilibrium of water resources and consumptions in the basin by the prospect to 2040 year. So far, the MWWF has tried to understand and deal with regional diversity in legal systems as well as conflicts between private interests and public welfare in water allocation and management. At

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

    OpenAIRE

    Riah, N.; Béna, Gilles; Djekoun, A.; Heulin, K.; De Lajudie, Philippe; Laguerre, G.

    2014-01-01

    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...

  12. Fluvial transport and surface enrichment of arsenic in semi-arid mining regions: examples from the Mojave Desert, California.

    Science.gov (United States)

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

    2012-07-01

    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.

  13. Spatial Distribution of Aboveground Carbon Stock of the Arboreal Vegetation in Brazilian Biomes of Savanna, Atlantic Forest and Semi-Arid Woodland.

    Science.gov (United States)

    Scolforo, Henrique Ferraco; Scolforo, Jose Roberto Soares; Mello, Carlos Rogerio; Mello, Jose Marcio; Ferraz Filho, Antonio Carlos

    2015-01-01

    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.

  14. Potential of the Thermal Infrared Wavelength Region to predict semi-arid Soil Surface Properties for Remote Sensing Monitoring

    Science.gov (United States)

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

    2014-05-01

    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

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

    Directory of Open Access Journals (Sweden)

    Yasemin KUSLU

    2016-09-01

    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.

  16. A Two-source Energy Balance Model for estimating evapotranspiration over an olive orchard in a semi-arid region of Morocco

    Science.gov (United States)

    Ezzahar, Jamal; Chehbouni, Abdelghani; Er-Raki, Salah; Aouade, Ghizlane; Khabba, Said; Merlin, Olivier; Boulet, Gilles; Jarlan, Lionel

    2016-04-01

    In arid and semi-arid regions, about 85% of the available water is used for irrigated agriculture, and therefore a sound and efficient irrigation practice is an important step towards achieving sustainable management of water resources in these regions. In this regard, a better understanding of the water balance is essential for exploring water-saving techniques. One of the most important components of the water balance in semi-arid areas is the evapotranspiration (ET). Therefore, a precise estimation evapotranspiration is of crucial importance for agricultural water management. In this work, a two source energy balance model (TSEB) is used to estimate ET over an irrigated olive orchard located near located near to the Marrakech city (Centre of Morocco). In addition to its simplicity, TSEB does not require a large number of input parameters that are not readily available. Evapotranspiration and micrometeorological parameters were continuously measured during the year 2003 in order to evaluate the performance of TSEB estimates. The comparison between daily estimated and measured evapotranspiration yielded a good agreement although the complexity of the study surface with a correlation coefficient of 0.78 and a root mean square of 61.9wm-².

  17. Jojoba - a promising plant for the semi-arid regions. [North America, plants, seeds, oils, waxes, growth, cultivation, lubricants, guayule, mesquite

    Energy Technology Data Exchange (ETDEWEB)

    Yermanos, D.M.

    1979-01-01

    As a result of the world-wide concern for conservation of resources and for the development of new renewable resources a great deal of attention has been directed towards the development of jojoba as a potential new crop for semi-arid regions. Jojoba grows wild in the Southwestern U.S. and N. Mexico, in areas where the annual precipitation is 4''-15''. Under cultivation it appears to grow satisfactorily in areas of marginal soil fertility, high salinity and high atmospheric temperatures. It appears to have no major natural enemies and to be tolerant to chemical treatments, if they were to become necessary. It is perennial with an assumed life span in excess of 150 years. Jojoba seed has an average weight of about 0.5 grams per seed, and it contains a unique liquid wax which is a superior lubricant and a potential replacement of whale oil, obtained from the sperm whale, and endangered species. Thus, jojoba has a double appeal, first as a potential crop of semi-arid regions requiring low cultural and energy inputs and second as a source of a valuable commodity. It should be pointed out that a cheap and abundant source of lubricants will disappear when our stock of fossil fuels are exhausted and that none of our new sources of energy have lubricants as by-products. Finally, jojoba could be grown with other companion crops such as guayule or mesquite for more diversified farming.

  18. Co-occurrence of arsenic and fluoride in groundwater of semi-arid regions in Latin America: genesis, mobility and remediation.

    Science.gov (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

    2013-11-15

    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.

  19. A Case Study of the Impacts of Dust Aerosols on Surface Atmospheric Variables and Energy Budgets in a Semi-Arid Region of China

    Institute of Scientific and Technical Information of China (English)

    LING Xiao-Lu; GUO Wei-Dong; ZHANG Le; ZHANG Ren-Jian

    2010-01-01

    The authors present a case study investigatingthe impacts of dust aerosols on surface atmospheric variables and energy budgets in a semi-arid region of China.Enhanced observational meteorological data, radiative fluxes, near-surface heat fluxes, and concentrations of dust aerosols were collected from Tongyu station, one of the reference sites of the International Coordinated Energy and Water Cycle Observations Project (CEOP), during a typical dust storm event in June 2006. A comprehensive analysis of these data show that in this semi-arid area, higher wind velocities and a continuously reduced air pressure were identified during the dust storm period.Dust storm events are usually associated with low relative humidity weather conditions, which result in low latent heat flux values. Dust aerosols suspended in the air decrease the net radiation, mainly by reducing the direct solar radiation reaching the land surface. This reduction in net radiation results in a decrease in soil temperatures at a depth of 2 cm. The combination of increased air temperature and decreased soil temperature strengthens the energy exchange of the atmosphere-earth system, increasing the surface sensible heat flux. After the dust storm event,the atmosphere was dominated by higher pressures and was relatively wet and cold. Net radiation and latent heat flux show an evident increase, while the surface sensible heat flux shows a clear decrease.

  20. 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.

    Science.gov (United States)

    Rahmati, Omid; Melesse, Assefa M

    2016-10-15

    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.

  1. Coexistence and geographical distribution of Leguminosae in an area of Atlantic forest in the semi-arid region of Brazil

    Institute of Scientific and Technical Information of China (English)

    Jacira R. LIMA; Vidal F. MANSANO; Francisca S. ARA(U)JO

    2012-01-01

    Understanding the factors that affect plant species distribution and coexistence in areas with high plant species diversity is a challenge for ecologists.According to some authors,species occupy specific niches,but for others,species coexistence and geographical distribution patterns are random.Floristic composition of the family Leguminosae was studied on moist and dry slopes of the Baturité mountains in semi-arid northeastern Brazil and was compared with findings for other plant formations elsewhere in Brazil.Substantial floristic differences were found between the moist windward and dry leeward slopes of the Baturité mountains despite their close geographical proximity.The leeward slope was slightly more diverse than the windward slope.Similarity analyses showed that the windward face is floristically allied to the Amazon forest,whereas the leeward slope is similar to other dry-area formations of northeastern Brazil,such as thorny woodland (caatinga) and seasonal forests.The strong floristic differences that were observed between the windward and leeward slopes corroborate the theory of ecological niche conservatism,which holds that species occurrence is closely linked to environmental factors,such as temperature and precipitation.

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

    Directory of Open Access Journals (Sweden)

    Mawloud GUERMOUI

    2016-07-01

    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.

  3. Physical and chemical degradation of grassland soils in semi-arid regions: A case from Central Anatolia, Turkey

    Science.gov (United States)

    Yaşar Korkanç, Selma; Korkanç, Mustafa

    2016-12-01

    The aim of this study is to determine some hydro-physical and chemical characteristics of soils on the grassland areas under semi-arid conditions in terms of soil degradation processes. Three sampling plots of 20 × 20 m size were selected from the Emen Plain as Locations-I, II and III basing on the area covered with vegetation and visual soil properties; and total 108 soil samples from 2 points and 3 depth levels (0-20 cm, 20-40 cm, 40-60 cm) of each sampling plot. Soils of the research area are in degradation process in terms of some physical and chemical characteristics. It was observed that soil properties (i.e. bulk density, total porosity, organic matter, pH, electrical conductivity and saturated hydraulic conductivity) in Location-II and Location-III changed negatively in comparison to Location-I almost at all depths. In the Location-III grassland, bulk density, pH, electrical conductivity and Na + values are higher than those in Location-I, whereas the organic matter, total porosity and saturated hydraulic conductivity values are low. Grassland area is vulnerable to erosion. High Exchangeable Sodium Percentage (ESP) values in Locations-II and III indicates the sodicity problem in these areas.

  4. Sedum-dominated green-roofs in a semi-arid region increase CO2 concentrations during the dry season.

    Science.gov (United States)

    Agra, Har'el; Klein, Tamir; Vasl, Amiel; Shalom, Hadar; Kadas, Gyongyver; Blaustein, Leon

    2017-04-15

    Green roofs are expected to absorb and store carbon in plants and soils and thereby reduce the high CO2 concentration levels in big cities. Sedum species, which are succulent perennials, are commonly used in extensive green roofs due to their shallow root system and ability to withstand long water deficiencies. Here we examined CO2 fixation and emission rates for Mediterranean Sedum sediforme on green-roof experimental plots. During late winter to early spring, we monitored CO2 concentrations inside transparent tents placed over 1m(2) plots and followed gas exchange at the leaf level using a portable gas-exchange system. We found high rates of CO2 emission at daytime, which is when CO2 concentration in the city is the highest. Both plot- and leaf-scale measurements showed that these CO2 emissions were not fully compensated by the nighttime uptake. We conclude that although carbon sequestration may only be a secondary benefit of green roofs, for improving this ecosystem service, other plant species than Sedum should also be considered for use in green roofs, especially in Mediterranean and other semi-arid climates.

  5. ESTIMATION OF EXTRACELLULAR LIPOLYTIC ENZYME ACTIVITY BY THERMOPHILIC BACILLUS SP. ISOLATED FROM ARID AND SEMI-ARID REGION OF RAJASTHAN, INDIA

    Directory of Open Access Journals (Sweden)

    Deeksha Gaur

    2012-10-01

    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.

  6. Pandemic influenza A (H1N1 2009: epidemiological analysis of cases in a tropical/semi-arid region of Brazil

    Directory of Open Access Journals (Sweden)

    Roberto da Justa Pires Neto

    2013-04-01

    Full Text Available Introduction The year 2009 marked the beginning of a pandemic caused by a new variant of influenza A (H1N1. After spreading through North America, the pandemic influenza virus (H1N1 2009 spread rapidly throughout the world. The aim of this study was to describe the clinical and epidemiological characteristics of cases of pandemic influenza in a tropical/semi-arid region of Brazil. Methods A retrospective study analyzed all suspected cases of pandemic influenza (H1N1 2009 reported in the Ceará State through the National Information System for Notifiable Diseases during the pandemic period between 28 April, 2009 and November 25, 2010. Results A total of 616 suspected cases were notified, 58 (9.4% in the containment phase and 558 (90.6% in the mitigation phase. Most cases were of affected young people resident in the City of Fortaleza, the largest urban center in the State of Ceará. The most frequent symptoms presented by the cases with confirmed infection were fever, cough, myalgia, arthralgia, and nasal congestion. Mortality rate was 0.0009/1,000 inhabitants and lethality was 5.6%. Deaths were observed only in the mitigation phase. Mortality rates were similar for both sexes but were higher in the age group under 5 years. Conclusions The study suggests that the influenza A (H1N1 pandemic in this tropical/semi-arid region had a lower magnitude when compared to states in the Southern and Southeastern regions of Brazil.

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

    Science.gov (United States)

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

    2015-12-01

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

  8. 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

    2008-07-01

    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)

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

    Directory of Open Access Journals (Sweden)

    Anne Evelyne Franco de Souza

    2010-09-01

    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.

  10. Ectoparasite Infestations and Canine Infection by Rickettsiae and Ehrlichiae in a Semi-Arid Region of Northeastern Brazil.

    Science.gov (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

    2015-11-01

    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.

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

    Science.gov (United States)

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

    2016-04-01

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

  12. Determination of unit nutrient loads for different land uses in wet periods through modelling and optimization for a semi-arid region

    Science.gov (United States)

    Özcan, Zeynep; Kentel, Elçin; Alp, Emre

    2016-09-01

    Diffuse pollution abatement has been a challenge for decision-makers because of the intermittent nature and difficulty of identifying impacts of non-point sources. Depending on the degree of complexity of the system processes and constraints related to time, budget and human resources, variety of tools are used in diffuse pollution management. Decision-makers prefer to use rough estimates that require limited time and budget, in the preliminary assessment of diffuse pollution. The unit pollution load method which is based on the pollution generation rate per unit area and time for a given land use can aid decision-makers in the preliminary assessment of diffuse pollution. In this study, a deterministic distributed watershed model, SWAT is used together with nonlinear optimization models to estimate unit nutrient pollution loads during wet periods for different land use classes for the semi-arid Lake Mogan watershed that is dominated by agricultural activities. Extensive data sets including in-stream water quality and flowrate measurements, meteorological data, land use/land cover (LULC) map developed using remote sensing algorithms, information about agricultural activities, and soil data are used to calibrate and verify the hydraulic and water quality components of SWAT model. Results show that the unit total nitrogen (TN) and total phosphorus (TP) loads (0.46 kg TN/ha/yr and 0.07 kg TP/ha/yr) generated from the watershed during wet periods are very close to the minimum values of the loads specified in the literature and highly depend on the variations in rainfall. Estimated unit nutrient loads both at watershed scale and for different land use classes can be used to assess diffuse pollution control measures for similar regions with semi-arid conditions and heavy agricultural activity.

  13. 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

    2008-01-01

    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.

  14. Hydrological Connectivity and Science and Policy Integration Issues for Aquatic Resource Jurisdictional Determinations in a Semi-Arid Region of the Western U.S

    Science.gov (United States)

    Caruso, B. S.

    2012-12-01

    Rivers and streams are becoming increasingly stressed and degraded, and wetlands lost, due to human development and associated management policies and actions that are generally ineffective for aquatic resources protection and restoration. In the semi-arid western U.S., these issues are more severe due to the limited quantity of water and aquatic resources, the magnified role of their ecological services in drier landscapes, and increasing impacts from urbanization and energy development. However, a significant disconnect between policy and science exists that leads to continued degradation of surface waters. Supreme Court decisions and joint Federal agency guidance for determining jurisdiction as 'waters of the US' that can be protected under Clean Water Act Section 404 (permitting discharge of dredged and fill materials into wetlands and other waters) are good examples of this disconnect. The hydrological and ecological connectivity of intermittent and ephemeral streams and wetlands with downstream navigable waters is a critical issue that must be evaluated to determine jurisdiction, but this can be a complex endeavour in semi-arid regions. The hydrological connectivity and key science and policy integration issues for stream and wetland jurisdictional determinations (JDs) were evaluated for a semi-arid region of the western U.S. (Environmental Protection Agency [EPA] Region 8), including much of the Rocky Mountains, Great Plains and Colorado Plateau. The key scientific approaches recommended in the agency guidance were analyzed in detail. An evaluation was performed of a sample of JDs reviewed by EPA Region 8 and their outcomes in terms of aquatic resources that were considered non-jurisdictional. An analysis of stream types and characteristics across the region using available digital spatial analysis tools was performed. A subset of finalized JDs issued by COE was reviewed to analyze the scientific information used to evaluate connectivity to downstream waters

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

    Directory of Open Access Journals (Sweden)

    Marcelo de Andrade Ferreira

    2009-07-01

    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

  16. Topological and geometrical analysis of a low-dimensional chaotic model obtained for the dynamics of cereal crops cycles observed from satellite in semi-arid region

    Science.gov (United States)

    Mangiarotti, Sylvain

    2014-05-01

    A low-dimensional chaotic model was recently obtained for the dynamics of cereal crops cycles in semi-arid region [1]. This model was obtained from one single time series of vegetation index measured from space. The global modeling approach [2] was used based on powerful algorithms recently developed for this purpose [3]. The resulting model could be validated by comparing its predictability (a data assimilation scheme was used for this purpose) with a statistical prediction approach based on the search of analogous states in the phase space [4]. The cereal crops model exhibits a weakly dissipative chaos (DKY = 2.68) and a toroidal-like structure. At present, quite few cases of such chaos are known and these are exclusively theoretical. The first case was introduced by Lorenz in 1984 to model the global circulation dynamics [5], which attractor's structure is remained poorly understood. Indeed, one very powerful way to characterize low-dimensional chaos is based on the topological analysis of the attractors' flow [6]. Unfortunately, such approach does not apply to weakly dissipative chaos. In this work, a color tracer method is introduced and used to perform a complete topological analysis of both the Lorenz-84 system and the cereal crops model. The usual stretching and squeezing mechanisms are easily detected in the attractors' structure. A stretching taking place in the globally contracting direction of the flow is also found in both attractors. Such stretching is unexpected and was not reported previously. The analysis also confirms the toroidal type of chaos and allows producing both the skeleton and algebraic descriptions of the two attractors. Their comparison shows that the cereal crops attractor is a new attractor. References [1] Mangiarotti S., Drapreau L., Letellier C., 2014. Two chaotic global models for cereal crops cycles observed from satellite in Northern Morocco. revision submitted. [2] Letellier C., Aguirre L.A., Freitas U.S., 2009. Frequently

  17. 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.

  18. Water and Carbon Fluxes in a Semi-Arid Region Floodplain: Multiple Approaches to Constrain Estimates of Seasonal- and Depth Dependent Fluxes at Rifle, Colorado

    Science.gov (United States)

    Tokunaga, T. K.; Wan, J.; Dong, W.; Kim, Y.; Williams, K. H.; Conrad, M. E.; Christensen, J. N.; Bill, M.; Faybishenko, B.; Hobson, C.; Dayvault, R.; Long, P. E.; Hubbard, S. S.

    2014-12-01

    The importance of floodplains as links between watersheds and rivers highlights the need to understand water and carbon fluxes within floodplain profiles, from their surface soil, through the vadose zone and underlying groundwater. Here, we present results of field and laboratory measurements conducted to quantify fluxes at a remediated uranium/vanadium mill tailings site on a floodplain at Rifle, Colorado. This semi-arid site has a vegetated, locally derived fill soil that replaced the original milling-contaminated soil to a depth of about 1.5 m. The fill soil overlies about 4.5 m of native sandy and cobbly alluvium containing the shallow aquifer. The aquifer generally drains into the Colorado River and is underlain by low permeability Wasatch Formation shale. Within this system, key issues being investigated include water and carbon fluxes between the vadose zone and aquifer, and CO2 fluxes through the vadose zone soil out to the atmosphere. Magnitudes of these fluxes are typically low, thus challenging to measure, yet increasingly important to quantify given the expansion of arid and semi-arid regions under changing climate. The results of field investigations demonstrated that the annual water table rise and fall are driven by snowmelt runoff into the Colorado River in late spring to early summer. Tensiometer data indicate that net recharge from the deeper part of the vadose zone into groundwater occurs later in summer, after water table decline. The effectiveness of summer evapotranspiration in limiting groundwater recharge is reflected in water potentials decreasing to as low as -3 MPa within the upper 1.5 m of the vadose zone. Examination of the historical precipitation record further indicates that net recharge only occurs in years with above-average precipitation during winter and spring. These short intervals of net recharge also facilitate C transport into groundwater because of higher organic C concentrations in the vadose zone. Fluxes of CO2 measured

  19. [Simulation on the restoration effect of soil moisture in alfalfa (Medicago sativa)-grain rotation system in semi-arid and drought-prone regions of Loess Plateau].

    Science.gov (United States)

    Wang, Xue-Chun; Li, Jun; Fang, Xin-Yu; Sun, Jian; Tahir, Muhammad Naveed

    2011-01-01

    With the combination of field survey and EPIC modeling, this paper simulated the restoration effect of soil moisture in different alfalfa (Medicago sativa)-grain rotation systems in semi-arid and drought-prone regions of Loess Plateau. In perennial alfalfa field and in grain crop field after alfalfa, the correlation coefficients between the simulated and observed values of soil moisture content in 0-10 m layer were larger than 0.9 (P alfalfa field. During the cultivation of alfalfa, the soil moisture content in the layers at 8-10 m depth should not be less than 5.7%. Considering the sustainable development of agricultural production, the appropriate cultivation duration of alfalfa should be 4-6 years and no more than 8 years. For the restoration of soil moisture after alfalfa cultivation in the study regions, the rotation system potato (Solanum tuberosum) --> potato --> spring wheat (Triticum aestivum) could be adopted, and alfalfa could be cultivated again after 32-33 years.

  20. Genotypic and symbiotic diversity of Rhizobium populations associated with cultivated lentil and pea in sub-humid and semi-arid regions of Eastern Algeria.

    Science.gov (United States)

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

    2014-07-01

    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.

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

    Directory of Open Access Journals (Sweden)

    K. Banerjee

    2013-01-01

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

  2. Evaluation of hydrological balance and its variability in arid and semi-arid regions of Eurasia from ECMWF 15 year reanalysis

    Science.gov (United States)

    Yatagai, Akiyo

    2003-10-01

    Hydrometeorological cycles over arid and semi-arid regions in mid-latitude Eurasia (the Silk Road region) were investigated using meteorological reanalysis data for the period 1979-93, available from the European Centre for Medium-range Weather Forecasts (ECMWF).Results show that seasonal changes of moisture balance in Turkey and central Asia, hereafter referred to as the western region, differ from those in the Taklimakan Desert and Loess Plateau, hereafter referred to as the eastern region. Here, we equate evaporation minus precipitation with the divergence field of the vertically integrated water vapour flux. In the western region, precipitation and positive convergence C of moisture primarily occurs during October-March. In contrast, the eastern region receives precipitation and has its positive C occurring during June-August. As a result, the eastern region has nearly simultaneous seasonal peaks in precipitation P and evapotranspiration E, whereas the western region has minimum P and maximum E in summer.The main annual moisture route for the Silk Road region is from the west to east; however, moisture also comes from the north in July. Over Turkey, moisture arrives from the west and south. In central Asia, however, most of the moisture comes from the west, the convergence peaks in March, and moisture from the south and west is also greater during this month. In the Loess Plateau, moisture enters from the west, the north, and the south, and exits to the east. In July, the peak precipitation and convergence season, all moisture flows are greater for the entire region, and a large influx of moisture from the south occurs during the summer season. The moisture from the south, the monsoonal flow, has a large interannual variability. Copyright

  3. Hydraulic parameters estimation by using an approach based on vertical electrical soundings (VES) in the semi-arid Khanasser valley region, Syria

    Science.gov (United States)

    Asfahani, Jamal

    2016-05-01

    A new alternative approach based on using Vertical electrical sounding (VES) technique is proposed for computing the hydraulic conductivity K of an aquifer. The approach takes only the salinity of the groundwater into consideration. VES measurements in the locations, where available water samples exist, are required in such an approach, in order to calibrate and establish empirical relationships between transverse resistance Dar-Zarrouck TR parameter and modified transverse resistance MTR, and between MTR and transmissivity T. Those relationships are thereafter used to extrapolate the transmissivity even in the VES points where no water samples exist. This approach is tested and practiced in the Khanasser valley, Northern Syria, where the hydraulic conductivity of the Quaternary aquifer is computed. An acceptable agreement is found between the hydraulic conductivity values obtained by the proposed approach and those obtained by the pumping test which range between 0.864 and 8.64 m/day (10-5 and 10-4 m/s). The Quaternary aquifer transmissivity of the Khanasser Valley, has been characterized by using this approach and by adapting the MTR parameter. The transmissivity varies between a minimum of 79 m2/day and a maximum of 814 m2/day, with an average of 283 m2/day and a standard deviation of 145 m2/day. The easy and inexpensive approach proposed in this paper can be applied in other semi arid regions.

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

    Science.gov (United States)

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

    2016-08-01

    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.

  5. Identifying and managing risk factors for salt-affected soils: a case study in a semi-arid region in China.

    Science.gov (United States)

    Zhou, De; Xu, Jianchun; Wang, Li; Lin, Zhulu; Liu, Liming

    2015-07-01

    Soil salinization and desalinization are complex processes caused by natural conditions and human-induced risk factors. Conventional salinity risk identification and management methods have limitations in spatial data analysis and often provide an inadequate description of the problem. The objectives of this study were to identify controllable risk factors, to provide response measures, and to design management strategies for salt-affected soils. We proposed to integrate spatial autoregressive (SAR) model, multi-attribute decision making (MADM), and analytic hierarchy process (AHP) for these purposes. Our proposed method was demonstrated through a case study of managing soil salinization in a semi-arid region in China. The results clearly indicated that the SAR model is superior to the OLS model in terms of risk factor identification. These factors include groundwater salinity, paddy area, corn area, aquaculture (i.e., ponds and lakes) area, distance to drainage ditches and irrigation channels, organic fertilizer input, and cropping index, among which the factors related to human land use activities are dominant risk factors that drive the soil salinization processes. We also showed that ecological irrigation and sustainable land use are acceptable strategies for soil salinity management.

  6. Identification of spatiotemporal patterns of biophysical droughts in semi-arid region – a case study of the Karkheh river basin in Iran

    Directory of Open Access Journals (Sweden)

    B. Kamali

    2015-06-01

    Full Text Available This study aims at identifying historical patterns of meteorological, hydrological, and agricultural (inclusively biophysical droughts in the Karkheh River Basin (KRB, one of the nine benchmark watersheds of the CGIAR Challenge Program on Water and Food. Standardized precipitation index (SPI, standardized runoff index (SRI, and soil moisture deficit index (SMDI were used to represent the above three types of droughts, respectively. The three drought indices were compared across temporal and spatial dimensions. Variables required for calculating the indices were obtained from the Soil and Water Assessment Tool (SWAT constructed for the region. The model was calibrated based on monthly runoff and yearly wheat yield using the Sequential Uncertainty Fitting (SUFI-2 algorithm. Five meteorological drought events were identified in the studied period (1980–2004, of which four corresponded with the hydrological droughts with 1–3 month lag. The meteorological droughts corresponded well with the agricultural droughts during dry months (May–August, while the latter lasted for a longer period of time. Analysis of drought patterns showed that southern parts of the catchment were more prone to agricultural drought, while less influenced by hydrological drought. Our analyses highlighted the necessity for monitoring all three aspects of drought for a more effective watershed management. The analysis on different types of droughts in this study provides a framework for assessing their possible impacts under future climate change in semi-arid areas.

  7. Identification of spatiotemporal patterns of biophysical droughts in semi-arid region - a case study of the Karkheh river basin in Iran

    Science.gov (United States)

    Kamali, B.; Abbaspour, K. C.; Lehmann, A.; Wehrli, B.; Yang, H.

    2015-06-01

    This study aims at identifying historical patterns of meteorological, hydrological, and agricultural (inclusively biophysical) droughts in the Karkheh River Basin (KRB), one of the nine benchmark watersheds of the CGIAR Challenge Program on Water and Food. Standardized precipitation index (SPI), standardized runoff index (SRI), and soil moisture deficit index (SMDI) were used to represent the above three types of droughts, respectively. The three drought indices were compared across temporal and spatial dimensions. Variables required for calculating the indices were obtained from the Soil and Water Assessment Tool (SWAT) constructed for the region. The model was calibrated based on monthly runoff and yearly wheat yield using the Sequential Uncertainty Fitting (SUFI-2) algorithm. Five meteorological drought events were identified in the studied period (1980-2004), of which four corresponded with the hydrological droughts with 1-3 month lag. The meteorological droughts corresponded well with the agricultural droughts during dry months (May-August), while the latter lasted for a longer period of time. Analysis of drought patterns showed that southern parts of the catchment were more prone to agricultural drought, while less influenced by hydrological drought. Our analyses highlighted the necessity for monitoring all three aspects of drought for a more effective watershed management. The analysis on different types of droughts in this study provides a framework for assessing their possible impacts under future climate change in semi-arid areas.

  8. Growth of seven perennial plant species adapted to the Brazilian Semi-Arid Crescimento de sete espécies vegetais perenes adaptadas ao Semi-Árido brasileiro

    Directory of Open Access Journals (Sweden)

    Paulo Sérgio Lima e Silva

    2007-12-01

    Full Text Available Measuring plant height (y and canopy diameter (x in trees may not be an easy task, but stem diameter (z can be more easily evaluated. This work's objective was two-fold: evaluate the growth of species adapted to the Brazilian Semi-Arid Region in the first two years of age, and obtain linear equations to estimate y and x from z, in those species. A random block design with four replications was employed. The values for x, z, and y were measured biannually from October/2003 to March/2005. Prosopis juliflora and Mimosa caesalpiniaefolia showed the highest stem diameter and plant height values, respectively, and both showed the highest canopy diameter. In the equations to estimate plant height from the stem diameter the value of the coefficient of determination (R² ranged from 0.76 (Tamarindus indica and Leucaena leucocephala to 0.92 (Prosopis juliflora and Azadirachta indica. In the equations that allowed to estimate the crown diameter from the stem diameter the R² value ranged from 0.70 (Leucaena leucocephala to 0.92 (Azadirachta indica.A mensuração da altura da planta (y e do diâmetro da copa (x em árvores pode não ser tarefa fácil, mas o diâmetro do caule (z pode ser avaliado mais facilmente. Este trabalho teve por objetivos avaliar o crescimento de espécies adaptadas ao Semi-Árido brasileiro, nos primeiros dois anos de idade, e obter equações lineares para estimar y e x a partir de z, nessas espécies. Utilizou-se o delineamento de blocos ao acaso com quatro repetições. Os valores de x, z e y foram medidos semestralmente de outubro/2003 a março/2005. Prosopis juliflora e Mimosa caesalpiniaefolia apresentaram os maiores diâmetros do caule e altura da planta, respectivamente, e ambas apresentaram o maior diâmetro da copa. Nas equações para estimar a altura da planta a partir do diâmetro do caule, o valor do coeficiente de determinação (R² variou de 0,76 (Tamarindus indica and Leucaena leucocephala a 0,92 (Prosopis

  9. 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.

    Science.gov (United States)

    Hoffman, M Timm; Rohde, Richard Frederick

    2011-01-01

    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.

  10. How To Assess The Future Tree-Cover Potential For Reforestation Planning In Semi-Arid Regions? An Attempt Using The Vegetation Model ORCHIDEE

    Science.gov (United States)

    Rajaud, A.; De Noblet-Ducoudré, N.

    2015-12-01

    More and more reforestation projects are undertaken at local to continental scales to fight desertification, to address development challenges, and to improve local living conditions in tropical semi-arid regions. These regions are very sensitive to climatic changes and the potential for maintaining tree-covers will be altered in the next decades. Therefore, reforestation planning needs predicting the future "climatic tree-cover potential": the optimum tree-fraction sustainable in future climatic states. Global circulation models projections provide possible future climatologies for the 21st century. These can be used at the global scale to force a land-surface model, which in turn simulates the vegetation development under these conditions. The tree cover leading to an optimum development may then be identified. We propose here to run a state-of-the-art model and to assess the span and the relevance of the answers that can be obtained for reforestation planning. The ORCHIDEE vegetation model is chosen here to allow a multi-criteria evaluation of the optimum cover, as it returns surface climate state variables as well as vegetation functioning and biomass products. It is forced with global climate data (WFDEI and CRU) for the 20th century and models projections (CMIP5 outputs) for the 21st century. At the grid-cell resolution of the forcing climate data, tree-covers ranging from 0 to 100% are successively prescribed. A set of indicators is then derived from the model outputs, meant for modulating reforestation strategies according to the regional priorities (e.g. maximize the biomass production or decrease the surface air temperature). The choice of indicators and the relevance of the final answers provided will be collectively assessed by the climate scientists and reforestation project management experts from the KINOME social enterprise (http://en.kinome.fr). Such feedback will point towards the model most urging needs for improvement.

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

    Directory of Open Access Journals (Sweden)

    Mark A. Nearing

    2015-06-01

    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.

  12. A combined deficit index for regional agricultural drought assessment over semi-arid tract of India using geostationary meteorological satellite data

    Science.gov (United States)

    Vyas, Swapnil S.; Bhattacharya, Bimal K.; Nigam, Rahul; Guhathakurta, Pulak; Ghosh, Kripan; Chattopadhyay, N.; Gairola, R. M.

    2015-07-01

    The untimely onset and uneven distribution of south-west monsoon rainfall lead to agricultural drought causing reduction in food-grain production with high vulnerability over semi-arid tract (SAT) of India. A combined deficit index (CDI) has been developed from tri-monthly sum of deficit in antecedent rainfall and deficit in monthly vegetation vigor with a lag period of one month between the two. The formulation of CDI used a core biophysical (e.g., NDVI) and a hydro-meteorological (e.g., rainfall) variables derived using observation from Indian geostationary satellites. The CDI was tested and evaluated in two drought years (2009 and 2012) within a span of five years (2009-2013) over SAT. The index was found to have good correlation (0.49-0.68) with standardized precipitation index (SPI) computed from rain-gauge measurements but showed lower correlation with anomaly in monthly land surface temperature (LST). Significant correlations were found between CDI and reduction in agricultural carbon productivity (0.67-0.83), evapotranspiration (0.64-0.73), agricultural grain yield (0.70-0.85). Inconsistent correlation between CDI and ET reduction was noticed in 2012 in contrast to consistent correlation between CDI and reduction in carbon productivity both in 2009 and 2012. The comparison of CDI-based drought-affected area with those from existing operational approach showed 75% overlapping regions though class-to-class matching was only 40-45%. The results demonstrated that CDI is a potential indicator for assessment of late-season regional agricultural drought based on lag-response between water supply and crop vigor.

  13. Tillage and residue effects on rainfed wheat and corn production in the Semi-Arid Regions of Northern China

    NARCIS (Netherlands)

    Wang, X.B.; Hoogmoed, W.B.; Perdok, U.D.; Cai, D.X.

    2003-01-01

    Field studies on tillage and residue management for spring corn were conducted at two sites, in Tunliu (1987-1990), and Shouyang (1992-1995) counties of Shanxi province in the semihumid arid regions of northern China. This paper discusses the effects of different fall tillage (winter fallow tillage)

  14. 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

    Directory of Open Access Journals (Sweden)

    Juliana Sampaio

    2011-03-01

    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.

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

    Directory of Open Access Journals (Sweden)

    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

  16. CHARACTERIZATION AND QUANTIFICATION OF NATIVE FOREST PATCHES IN A SECTOR OF THE SEMI-ARID LANDSCAPE AT THE MAULE’S REGION, CHILE

    Directory of Open Access Journals (Sweden)

    Yony Ormazábal

    2013-08-01

    Full Text Available http://dx.doi.org/10.5902/1980509810556In general, the Mediterranean forests have suffered high levels of fragmentation, mainly by anthropogenic action, as result of the productive activities of agriculture and livestock, human settlements and forest plantations of fast growing exotic species, leading to loss of continuity of natural forests, and thus a decrease of biodiversity. In this context, the objective of this study was to evaluate the potential use of satellite images and Geographic Information Systems (GIS to quantify and characterize the spatial evolution of native forests in a semi-arid landscape area at the Region of Maule, Chile. The study was conducted with Landsat-5 TM images of 2004 and 2008, which were classified by the supervised method where it was previously necessary to apply the atmospheric and the geometric corrections to reduce errors of interpretation and measurement. Within the analysis, it was incorporated digital thematic information of land use of the National Forestry Corporation (CONAF and also it was joined one of the latest techniques derived from remote sensing for studying changes in land cover, that is called Radiometric Rotation Controlled by No-Change Axis (RCNA. Finally, the fragmentation indexes were estimated for characterizing the spatial configuration of landscape. From the results of the digital classification it was possible to estimate landscape metrics that show significant differences in the structure of the study area between the two periods. In addition, it was generated an image of change 2004/2008 that allowed to evaluate the consistency of the RCEN technique, demonstrating the feasibility of using this alternative methodology for the detection of changes in terms of degradation and recovery of woodlands.

  17. Detection and differentiation of pollution in urban surface soils using magnetic properties in arid and semi-arid regions of northwestern China.

    Science.gov (United States)

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

    2014-01-01

    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.

  18. Index-based assessment of agricultural drought in a semi-arid region of Inner Mongolia, China

    Institute of Scientific and Technical Information of China (English)

    Rui LI; Atsushi TSUNEKAWA; Mitsuru TSUBO

    2014-01-01

    Agricultural drought is a type of natural disaster that seriously impacts food security. Because the rela-tionships among short-term rainfall, soil moisture, and crop growth are complex, accurate identification of a drought situation is difficult. In this study, using a conceptual model based on the relationship between water deficit and crop yield reduction, we evaluated the drought process in a typical rainfed agricultural region, Hailar county in Inner Mongolia autonomous region, China. To quantify drought, we used the precipitation-based Standardized Precipita-tion Index (SPI), the soil moisture-based Crop Moisture Index (CMI), as well as the Normalized Difference Vegeta-tion Index (NDVI). Correlation analysis was conducted to examine the relationships between dekad-scale drought indices during the growing season (May-September) and final yield, according to data collection from 2000 to 2010. The results show that crop yield has positive relationships with CMI from mid-June to mid-July and with the NDVI anomaly throughout July, but no correlation with SPI. Further analysis of the relationship between the two drought indices shows that the NDVI anomaly responds to CMI with a lag of 1 dekad, particularly in July. To examine the feasibility of employing these indices for monitoring the drought process at a dekad time scale, a detailed drought assessment was carried out for selected drought years. The results confirm that the soil moisture-based vegetation indices in the late vegetative to early reproductive growth stages can be used to detect agricultural drought in the study area. Therefore, the framework of the conceptual model developed for drought monitoring can be employed to support drought mitigation in the rainfed agricultural region of Northern China.

  19. LAS在西北半干旱地区的观测分析%Large Aperture Scintillometers(LAS)Observation in Semi-arid Regions of Northwestern China

    Institute of Scientific and Technical Information of China (English)

    黄山; 张文煜; 左洪超; 刘欣; 史永义

    2011-01-01

    In this paper, sensible heat flux in semi-arid region of northwestern China were calculated and analyzed by use of the observation data of Large Aperture Scintillometers (LAS) recorded per 30 minutes, the temperature, pressure data, and the observation data by Eddy Covariance System at Lanzhou University Semi-arid Climate and Environment Observatory during summer and winter of 2007.The values of the sensible heat flux in summer were bigger than that in winter, and there was a lag of peak value on diurnal variation curve in winter; at the similar weather conditions, the fluctuation of sensible flux in summer was bigger than that in winter.Weather condition had a great impact on the observations of LAS, the values of the sensible heat flux in sunny days were higher than that in cloudy days at the same season.Compared with sensible heat flux observed by Eddy Covariance System, the sensible heat flux measured by LAS was a little larger, but the values by the two methods showed a good agreement, and the correlation coefficient in summer was 0.95, and it was 0.98 in winter.%利用兰州大学半干旱气候与环境观测站2007年夏冬两季LAS观测数据.结合观测站气温、气压及同期的涡动相关仪30 min时间间隔的观测数据,计算分析了西北半干旱地区显热通量的变化特征,并将LAS所测结果与涡动相关仪的测量结果进行了对比分析.结果表明,在西北半干旱地区.夏季的显热通量值整体大于冬季,冬季显热通量的日变化峰值较夏季有明显的滞后性;在类似的天气状况下,夏季测得显热通量的波动要大于冬季;天气状况对LAS的观测结果有着很大的影响,在同一季节晴天显热通量较大,阴天较小;LAS测得显热通量H的值较涡动相关所得H值略微偏大.但LAS与涡动相关仪测得的显热通量有很好的符合性,复季相关系数为0.95,冬季相关系数为0.98.

  20. 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.

    2006-07-01

    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)

  1. Rain gauge network evaluation and optimal design using spatial correlation approach in arid and semi-arid regions of Iran

    Science.gov (United States)

    Nazaripour, Hamid; Mansouri Daneshvar, Mohammad Reza

    2016-06-01

    The present study is aimed at evaluation of a rain gauge network in order to optimize a network design. In this regard, point rainfall estimations were assessed using a spatial correlation approach in the Kerman region, Iran. This approach was implemented based on monthly rainfall data for existing 117 rain gauge stations in the study area. The results revealed that the regular arrangement of rain gauges could provide the reliable values for accurate rainfall estimation. Low density of rain gauge combined with the low rainfall values may result in strong increase of the interpolation errors. Based on the existing rain gauge network, the relative mean error of observed rainfalls (E a ) is less than 5 % over the study area. The spatial interpolation errors (E i ) were considered to optimize the design of rain gauge network at the confidence level of 85 %, where the mean errors were exhibited from 8.5 to 14 % in districts A and B, respectively. On this basis, about 46 locations were proposed for allocation of new stations. Therefore, it was suggested to relocate about 20 existing stations in order to achieve an accurate design.

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

    Directory of Open Access Journals (Sweden)

    Indira C. M. Gonçalves

    2016-01-01

    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.

  3. Edge effect of the ecotone of wetland and arid grassland in a semi-arid region of China

    Institute of Scientific and Technical Information of China (English)

    Ruiping HOU; Rui LI; Kebin ZHANG; Yunfang LIU

    2008-01-01

    The edge effect of plant communities was investigated in a wetland-dry grassland ecosystem at the Siertan Wetland in Yanchi County, Ningxia Hui Autonomous Region, China. Four transects lines, with each about 1 km long, were established for a vegetation survey in July 2005, along biotope gradients in four direc-tions: east, northeast, west and northwest. The data was analyzed using TWINSPAN classification method. The vegetation in this wetland was classified into three vegeta-tion types: halophytic marsh vegetation, meadow vegeta-tion and grassland vegetation. Based on the calculation of the community structure indices, the edge effect was studied which revealed distinct differences among those three vegetation zones along each transect line. The eco-tone had high richness indices (R), a high diversity index (SW) and ecological dominance (SP). Evenness, as mea-sured by the index (E), was less apparent. From the four transect lines, it appears that the ecotone in the northeast-erly direction scored higher in each community structure indicator than any of the other directions and those towards the northwest were least. The variation in the edge effect between the different transect lines is caused by human disturbances and topographic uplift.

  4. The role of economic analysis in groundwater management in semi-arid regions: the case of Nigeria

    Science.gov (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

  5. 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;

    2016-01-01

    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...... to overcome this issue. However, clear recommendations on the suitability of specific proxies to provide accurate biomass information in semi-arid to arid environments are still lacking. This study contributes to the understanding of using multispectral high-resolution satellite data (RapidEye), specifically...... 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...

  6. Emergy-based study on eco-economic system of arid and semi-arid region:a case of Gansu province,China

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    Taking Gansu province as a model case,this study provides an integrated analysis on the eco-economic system of arid and semi-arid region based on emergy synthesis theory. Through calculating the values of renewable emergy flow,non-renewable resources,imported emergy,exported emergy,waste emergy,and total emergy during the period of 1978-2007,the performance of Gansu eco-economic system was analyzed. The results indicated that the renewable emergy flow within the province basically remained steady state which was estimated at 2.99×1022 solar emjoules (sej) from 1978 to 2007. The imported emergy and exported emergy were estimated at 3.75×1017 sej and 2.99×1020 sej in 1978 and increased to 1.07×1022 sej and 1.44×1022 sej respectively in 2007. The nonrenewable emergy flow was estimated at 1.62×1022 sej and increased to 1.85×1023 sej,with annual growth rate of 8.7%,while the estimated total emergy was 4.58×1022 sej in 1978 and increased to 2.11×1023 sej in 2007,with annual growth rate of 5.41%. Our results indicate a deteriorate situation between economic development and environmental protection in the region. The rapid economic growth in the past thirty years was based on a great consumption of nonrenewable resource and caused continuous decrease in the capacity of sustainable development. The environmental loading ratio was 0.53 in 1978,increased to 6.06 in 2007,indicating a rapid degradation of the regional environment quality. We calculated that the actual population was 1.53 times the renewable resource population in 1978,increased to 7.06 times in 2007. During the period of 1978-2007,the emergy rose from 2.45×1015 sej/(capita·a) to 8.07×1015 sej/(capita·a). Our analysis revealed that the emergy density presented a trend of gradual increase,and then the emergy currency ratio in Gansu decreased from 7.08×1013 sej/Chinese Yuan to 7.82×1012 sej/Chinese Yuan.

  7. 关于中国半干旱区一种生态农业模式的探讨%Discussion on an Eco-Agriculture Model in the Semi-Arid Region of China

    Institute of Scientific and Technical Information of China (English)

    张培栋

    2005-01-01

    The semi-arid region of China covers an area of 2.2 × 106km2. Water shortage in this region is the core but not the only one factor for the sustainable de ment of agriculture. Effective application of the energy and all kinds of resources and overall maintenance of the balance of ecological environment must be emphasized for sustainable development of the agriculture in the region. The extensive development of rural yard-economy is the only way to realize the intensive agricultural development there. A modelis developed on the basis of our studies in recent years.

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

    Science.gov (United States)

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

    2015-04-01

    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

  9. Seroprevalence of peste des petits ruminants among domestic small and large ruminants in the semi-arid region of North-eastern Nigeria

    Directory of Open Access Journals (Sweden)

    Abdul-Dahiru El-Yuguda

    2013-09-01

    Full Text Available Background: Recent changes in the host range of peste des petits ruminants (PPR virus coupled with the presence of a hugeruminant population in the study area has stimulated our interest to carry out a sero-survey for PPR among the differentdomestic ruminant populations of semi-arid region of North-eastern (NE Nigeria.Materials and Methods: The prevalence of PPR virus antibodies among domestic animals (goat, sheep, cattle and camelpopulations in NE Nigeria was studied using virus neutralisation test (VNT and competitive enzyme-linked immunosorbentassay (c-ELISA.Results: An overall seroprevalence of 57% and 55% were revealed using VNT and c-ELISA, respectively. Significantdifference (p<0.05 in the prevalence of PPR antibodies was noted between the different species of animals tested. Highestseroprevalence of 76.5% was found in sheep followed by a decreasing order of prevalence in goat 51.6%, camels 27.8% andcattle 16.7%. Similar pattern of prevalence was noted when the sera were tested for PPR using c-ELISA antibody. There wasno significant difference in the sensitivity of both the procedures (VNT and c-ELISA when used for the detection of PPRantibody in test sera. However, differences were noted in their specificity based on the degree of cross reactivity between PPRand rinderpest (RP antibodies. Higher percentage of PPR positive sera (goats 64.8% and sheep 63.8% cross-reacted with RPvirus in VNT. None of the PPR positive sera from cattle and camels cross-reacted with RP virus in VNT and c-ELISA.Significant difference in gender and age was noted in the prevalence of PPR antibody among goats and sheep. Specificall,higher prevalence was found in females and the seroprevalence increased with age among the different age groups of goatsstudied. Analysis of the seasonal distribution of prevalence of PPR antibody in positive samples did not reveal any significantdifference between seasons.Conclusion:We conclude that PPR virus is actively circulating

  10. Larvicidal potential of wild mustard (Cleome viscosa) and gokhru (Tribulus terrestris) against mosquito vectors in the semi-arid region of Western Rajasthan.

    Science.gov (United States)

    Bansal, S K; Singh, Karam V; Sharma, Sapna

    2014-03-01

    effective as compared to the fruit extracts of T. terrestris indicating that active larvicidal principle may be present in the fruits of this plant species. The studywould be of great importance while formulating the control strategy, for vectors of malaria, dengue and lymphatic filariasis, based on alternative plant based insecticides in this semi-arid region.

  11. 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

    2009-12-01

    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

  12. 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

    2004-07-01

    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)

  13. Improving estimates of water resources in a semi-arid region by assimilating GRACE data into the PCR-GLOBWB hydrological model

    Science.gov (United States)

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

    2016-04-01

    An accurate estimate of water resources is critical for proper management of both agriculture and the local ecology, particularly in semi-arid regions where water is scarce. Imperfections in model physics, uncertainties in model land parameters and meteorological data, and the human impact on land changes often limit the accuracy of hydrological models in estimating water storages. To address this problem, this study investigated the assimilation of Terrestrial Water Storage (TWS) 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 of 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 performance of the GRACE Data Assimilation (DA) scheme was evaluated in terms of its impact on the TWS as well as on the individual hydrological storage estimates. The capability of GRACE DA to adjust the storage level was apparent not only in the TWS but also in the groundwater component, which had annual amplitude, phase, and long-term trend estimates closer to the GRACE observations. This study also assessed the impact of considering correlated errors in GRACE-based estimates. These were derived based on the error propagation approach using the full error variance-covariance matrices provided as a part of the GRACE data product. The assessment was carried out by comparing the EnKF results after excluding (EnKF 1D) and including (EnKF 3D) error correlations with the in situ groundwater data from 5 well sites, and the in situ streamflow data from two river gauges. Both EnKF 1D and 3D improved groundwater and streamflow estimates compared to the results from the PCR-GLOBWB alone (Ensemble Open Loop, EnOL). Although EnKF 3D was inferior to 1D at some groundwater measurement locations, on average, it showed equal or greater improvement in all metrics. For example

  14. 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

    2008-09-01

    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

  15. Climate warming threatens semi-arid forests in Inner Asia

    Science.gov (United States)

    WU, X.

    2015-12-01

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

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

    Science.gov (United States)

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

    2014-12-01

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

  17. Integrating management objectives and grazing strategies on semi-arid rangelands

    Data.gov (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...

  18. Influence of groundwater on the degradation of irrigated soils in a semi-arid region, the inner delta of the Niger River, Mali

    Science.gov (United States)

    Valenza, A.; Grillot, J. C.; Dazy, J.

    2000-08-01

    The problem of soil degradation through alkalinization/salinization in an irrigated area with a semi-arid climate was examined in the inner delta of the Niger River, Mali, by the study of groundwater hydraulics and hydrochemistry in an area recharged by irrigation water. On the basis of data analysis on various scales, it is concluded that the current extent of the surface saline soils is due to a combination of three factors: (1) the existence of ancient saline soils (solonchaks) resulting from the creation of a broad sabkha west of the former course of the Niger River, now called the Fala of Molodo. These saline crusts were gradually deposited during the eastward tilting of the tectonic block that supports the Niger River; (2) the irrigation processes during the recent reflooding of the Fala of Molodo (river diversion in 1950). These used very poorly mineralized surface water but reintroduced into the alluvial groundwater system - generally of a low permeability (K=10-6 m s-1) - salts derived from the ancient solonchaks; and (3) the redeposition of the dissolved salts on the surface due to the intense evapotranspiration linked to the present Sahelian climate. In this context, only efficient artificial draining of subsurface alluvial groundwater can eliminate most of the highly mineralized flow and thus reduce the current saline deposits.

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

    Science.gov (United States)

    Doummar, Joanna; Aoun, Michel; Andari, Fouad

    2016-04-01

    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

  20. Evaluating the influence of geo-environmental factors on gully erosion in a semi-arid region of Iran: An integrated framework.

    Science.gov (United States)

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

    2017-02-01

    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.

  1. Aerosol optical depth over a remote semi-arid region of South Africa from spectral measurements of the daytime solar extinction and the nighttime stellar extinction

    Science.gov (United States)

    Formenti, P.; Winkler, H.; Fourie, P.; Piketh, S.; Makgopa, B.; Helas, G.; Andreae, M. O.

    Spectral daytime aerosol optical depths have been measured at Sutherland, South Africa (32°22'S, 20°48'E), from January 1998 to November 1999. Sutherland is located in the semi-arid Karoo desert, approximately 400-km northeast from Cape Town. The site, remote from major sources of aerosols, hosts the South African Astronomical Observatory (SAAO), where nighttime stellar extinction is being measured. The comparison of daytime and nighttime measurements for the years 1998-1999 makes it possible to validate the astronomical dataset of aerosol optical depth ( τa) dating back to 1991. The 1998 and 1999 annually averaged daytime τa at 500 nm are 0.04±0.04 and 0.06±0.06, respectively. Half-day averages vary between 0.03 and 0.44, with peak values in August-September. This pronounced seasonality is linked to the biomass-burning season in the Southern Hemisphere. Smoke haze layers transported to Sutherland originated primarily on the African landmass at latitudes between 10° and 20°S and passed over Namibia and Angola. On one occasion, aerosols from fires in Brazil transported across the Atlantic Ocean were likely detected. The haze layers reaching Sutherland are therefore at least 2-3 days old. The spectral dependence of the aerosol optical depth for the smoke layers supports the bimodality of the volume size distribution for biomass burning aerosols. The accumulation mode has a volume modal diameter of 0.32 μm, consistent with the hypothesis of aged haze. The stellar measurements (1991-2001) show that, due to the eruption of Mt. Pinatubo, the atmospheric extinction depth at 550 nm in the years 1991-1993 increased by 33% with respect to the average value (0.14±0.03) for the period 1994-2001. Outside the Pinatubo event, extinction is largest in the period 1997-1999.

  2. The cactus effect: an alternative to the lupin effect for increasing ovulation rate in sheep reared in semi-arid regions?

    Science.gov (United States)

    Rekik, M; Gonzalez-Bulnes, A; Lassoued, N; Ben Salem, H; Tounsi, A; Ben Salem, I

    2012-04-01

    The present study evaluated the effects of supplementation with cactus cladodes on follicular dynamics and ovulatory response of sheep reared in semi-arid areas. A total of 76 ewes were distributed into two equal groups supplemented with either concentrated feed or cactus cladodes. After 30 days of supplementation, no differences were found between feeding regimens on the final live weight (LW; 41.5 ± 0.6 and 42.1 ± 0.7 kg in the Concentrate and Cactus groups respectively) and body condition score (BCS; 1.8 ± 0.3 and 1.8 ± 0.4 for Concentrate and Cactus group respectively). Moreover, no differences were found between the initial and the final values of both LW and BCS; thus, there were no effects of supplementation on any of both parameters. Analysis of follicular population showed that, during the follicular phase induced by ram effect, the number of follicles reaching ovulatory size increased in both groups. However, the number was always higher in Cactus ewes and, at oestrus, Cactus ewes had 1.6 ± 0.2 and Concentrate sheep had 1.2 ± 0.2 large follicles (p cactus for 6-10 days (1.7 ± 0.1) than in ewes supplied with cactus for more than 11 days (1.3 ± 0.1; p < 0.05), in sheep fed with concentrate for 6-10 days (1.2 ± 0.1; p < 0.01) and even than in individuals subjected to classical flushing with concentrate (1.3 ± 0.1; p < 0.05).

  3. 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

    2012-12-01

    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

  4. Water politics in Brazil subsidiarity and humanity aspects for the semi-arid sustainable river basin management

    Energy Technology Data Exchange (ETDEWEB)

    Guimaraes, Patricia Borba Vilar; Xavier, Yanko Marcius de Alencarr [Universidade Federal do Rio Grande do Norte (UFRN), Natal, RN (Brazil). Dept. de Direito Publico

    2010-02-15

    This paper examines Brazilian national constitutional law interpretation about water resources management, environmental protection and sustainable development principles. Institutional scenario is characterized under an economical format, important to conciliate human rights guaranties, national development and water protection. We provide subsidies for legal and institutional analysis considering human rights and an equity desirable scenario. Institutional context in Brazil assumes that Federal Law No. 9433/97 determined that water management must improve its multiple uses, decentralization and social participation. Water resources management in Brazil is legally and institutionally marked by the presence of the subsidiarity principle. We analyze the case in current national scene, with its consequent conflict in Sao Francisco River Basin, a semi arid Northeastern River Basin. This work also reflects some aspects of water pricing as defined by State politics. Some parameters are discussed as an elementary presupposition for water regulatory instruments that will define respective water management policy. Therefore, when defining criteria water fees, laws must comply with constitutional principles and the parameters established by the Brazilian Water Law (Law 9.433/97). The lack of reasonability and proportionality in dealing with the formal aspects and, specially, in defining water allocation, can obstruct the subsidiary principle application as determined by the Law 9433/97 and National Water Resources Policy. The question is observed in a more detailed focus over Northeastern Brazilian semi-arid region, where scarcity and traditional relations on politics are difficult to deal with, according to a renewed vision of the State and sustainable development principles. (author)

  5. Rapid warming accelerates tree growth decline in semi-arid forests of Inner Asia.

    Science.gov (United States)

    Liu, Hongyan; Park Williams, A; Allen, Craig D; Guo, Dali; Wu, Xiuchen; Anenkhonov, Oleg A; Liang, Eryuan; Sandanov, Denis V; Yin, Yi; Qi, Zhaohuan; Badmaeva, Natalya K

    2013-08-01

    Forests around the world are subject to risk of high rates of tree growth decline and increased tree mortality from combinations of climate warming and drought, notably in semi-arid settings. Here, we assess how climate warming has affected tree growth in one of the world's most extensive zones of semi-arid forests, in Inner Asia, a region where lack of data limits our understanding of how climate change may impact forests. We show that pervasive tree growth declines since 1994 in Inner Asia have been confined to semi-arid forests, where growing season water stress has been rising due to warming-induced increases in atmospheric moisture demand. A causal link between increasing drought and declining growth at semi-arid sites is corroborated by correlation analyses comparing annual climate data to records of tree-ring widths. These ring-width records tend to be substantially more sensitive to drought variability at semi-arid sites than at semi-humid sites. Fire occurrence and insect/pathogen attacks have increased in tandem with the most recent (2007-2009) documented episode of tree mortality. If warming in Inner Asia continues, further increases in forest stress and tree mortality could be expected, potentially driving the eventual regional loss of current semi-arid forests.

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

    Directory of Open Access Journals (Sweden)

    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.

  7. Seasonal variation of aerosol optical properties at AERONET of the semi-arid region in Loess Plateau%黄土高原半干旱区气溶胶光学特性季节变化特征

    Institute of Scientific and Technical Information of China (English)

    白鸿涛; 陈勇航; 王洪强; 张强; 郭铌; 王胜; 潘鹄; 张萍

    2011-01-01

    Semi - arid regions are defined as transition zones between arid and sub - humid belts where precipitation is less than the potential evaporation. Semi -arid lands, especially those located in mid -latitude inner continental regions, are some of the most sensitive areas to climate change. One of these regions is found in western China. During the last few decades, warm winters and dry springs occurred more frequently in northwestern China where, with disturbances brought about by human activity,large areas of vegetation were destroyed, thus giving rise to anthropogenie dust emissions. Understanding how human activity and the resulting dust emissions affect aerosol optical properties in these semi -arid regions is an essential step for developing mitigation and adaptation strategies to climate changes in these transition areas. In order to monitor the global aerosol optical properties, the U. S. space agency NASA and its partners established a worldwide network of ground - based observationswhich is an international aerosol automatic monitoring network called AERONET (Aerosol Robotic Network). The sun and sky diffuse radiation was measured and thene the aerosol optical properties are retrieved by using the sun and sky scanning spectral radiation observations. The products from the AERONET direct sun and sky radiance measurements are retrived through a rigorous calibration,cloud mask processing, and quality control. In this paper, the impact of dust aerosols on the semi - arid climate of northwestern China was analyzed using Version 2 Level 2 dataset from the AERONET site located in the semi - arid region in Loess Plateau in China, which is named as Lanzhou_city site. The seasonal variation of parameters of atmospheric aerosol optical properties such as aerosol optical thickness, Angstrom exponent, volume size distribution (dV(r)/dlnr), refractive index (n-ik) and single scattering albedo ( 0 ) were analyzed. The results show that the optical properties of the dust

  8. Understanding Hydrologic Processes in Semi-Arid Cold Climates

    Science.gov (United States)

    Barber, M. E.; Beutel, M.; Lamb, B.; Watts, R.

    2004-12-01

    Water shortages destabilize economies and ecosystems. These shortages are caused by complex interactions between climate variability, ecosystem processes, and increased demand from human activities. In the semi-arid region of the northwestern U.S., water availability during drought periods has already reached crisis levels and the problems are expected to intensify as the effects of global climate change and population growth continue to alter the supply and demand patterns. Many of the problems are critical to this region because hydropower, agriculture, navigation, fish and wildlife survival, water supply, tourism, environmental protection, and water-based recreation are vital to state economies and our way of life. In order to assess the spatial and temporal nature of hydrologic responses, consistent and comprehensive long-term data sets are needed. In response to these needs, we would like to propose the Spokane River drainage basin as a long-term hydrologic observatory. The Spokane River basin is located in eastern Washington and northern Idaho and is a tributary of the Columbia River. The watershed consists of several major surface water tributaries as well as natural and man-made lakes and reservoirs. With headwaters beginning in the Rocky Mountains, the drainage area is approximately 6,640 mi2. In addition to providing an excellent study area for examining many conventional water resource problems, the Spokane River watershed also presents a unique opportunity for investigating many of the hydrologic processes found in semi-arid cold climates. Snowfall in the watershed varies spatially between 35 inches near the mouth of the basin to over 112 inches at the headwaters. These varied hydrologic uses provide a unique opportunity to address many common challenges faced by water resource professionals. This broad array of issues encompasses science, engineering, agriculture, social sciences, economics, fisheries, and a host of other disciplines. In addition

  9. The Fragile Ecosystem Types in Arid and Semi-Arid Region of China and Their Degradation Causes%我国干旱半干旱地区脆弱生态系统及其退化成因

    Institute of Scientific and Technical Information of China (English)

    关中美; 郝成元

    2013-01-01

    In ecological and environmental problems of present world,ecological vulnerability is one of the focus issues.Based on analysis on three main courses in arid and semi-arid region of China,it is analyzed on the formation and traits of main type fragile ecological systems.In this study area,main courses includes grassland degradation,desertification and salinization while main fragile ecological systems refer to degraded grassland ecosystem,irrigated oasis ecosystem,desert ecosystem,wetland ecosystem and farming-pastoral ecosystem.In conclusion,both climate anomalies and human irrational activities are main reasons,which resulted in fragile ecosystem being in a vicious circle for a long time.The former refers to both climate change and climate variability while the latter includes over-grazing,disorder-reclaiming,excessiveutilizing of water resources,misuse and gouging natural resources,et al.These conclusions will provide theoretical basis so as to prevent further deterioration of ecosystem and comprehensive harnessing in arid and semi-arid region of China.%当今世界生态与环境的诸多问题中,生态系统脆弱性是焦点问题之一.依据我国干旱半干旱地区草场退化、土地沙漠化及盐碱化等三种主要问题的剖析结果,分析了退化草原生态系统、绿洲生态系统、荒漠生态系统、湿地生态系统、农牧交错生态系统等五类主要脆弱生态系统的成因和生态性状.最后得出结论:气候异常和人类非理性活动是造成脆弱生态系统长时期处于恶性循环的主要原因,前者表现在气候变化和气候变异两方面,后者则以超载放牧、无序垦荒、无度利用有限水资源、乱樵滥采资源等四类为主.这些研究结论为我国干旱半干旱地区防止脆弱生态系统进一步退化和生态综合整治提供了理论基础.

  10. 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.

    Science.gov (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

    2016-01-15

    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.

  11. Urban Rainwater Infrastructure System in Arid and Semi-arid Regions Based on Low Impact Development%基于LID的干旱半干旱区城市雨水设施体系模式

    Institute of Scientific and Technical Information of China (English)

    苗展堂; 王昭

    2013-01-01

    The traditional rainwater infrastructure planning ignored rainwater harvesting and reuse. The significance of restructuring urban rainwater facilities system based on low impact development was illustrated. The soil infiltration capacity as well as annual and daily rainfall was analyzed, and the areas of infiltration facilities in arid and semi-arid regions were accounted. A new infrastructure plan in which 1/10 of the residential area should be built into rainfall garden was put forward to achieve rainfall zero discharge.%在指出传统雨水基础设施规划建设具有忽略雨水资源化特点的基础上,阐明了基于LID理念重构城市雨水设施体系的意义.并通过对土壤渗透能力及年、日降雨量等条件进行分析的基础上,对干旱半干旱区城市入渗模式的渗透设施面积进行核算,提出了将小区的1/10面积建设为雨水花园从而实现雨水“零排放”的基础设施规划新思路.

  12. 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: gmontanha@fca.unesp.br; 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

    2010-07-01

    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)

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

    Energy Technology Data Exchange (ETDEWEB)

    Guentner, A.

    2002-09-01

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

  14. 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;

    2015-01-01

    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...

  15. 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: naper@ufpe.br; Araujo, Kassia; Silva, Gerson Flavio da; Raquel, Karine [ONG NAPER SOLAR, Recife, PE (Brazil). Centro de Estudos e Projetos], Email: nsolar@terra.com.br

    2006-07-01

    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

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

    OpenAIRE

    2007-01-01

    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...

  17. A regional field-based assessment of organic C sequestration and GHG balances in irrigated agriculture in Mediterranean semi-arid land

    Science.gov (United States)

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

    2016-04-01

    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, http://life-regadiox.es/) 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

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

    Directory of Open Access Journals (Sweden)

    Lounis Semara

    2013-12-01

    Full Text Available 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 preferred marketing policies. The model has been emerged as a result of functional typology established using the procedure categorical principal components analysis (CATPCA of optimal coding in SPSS [19. 2010]. Following this approach, five types of cattle productive orientation have been identified, the balanced mixed system (dairy-beef, beef mixed system, dairy mixed system, dairy system and beef system. These results showed that the breeders were oriented towards specialization (dairy or beef in less than 20% of situations. Farmers in our context prefer mixed systems when beef mixed system was the model type frequently encountered in the region (over than 50% of farms.

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

    Directory of Open Access Journals (Sweden)

    T.X. Zhu

    2014-11-01

    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.

  20. Recognition of shallow karst water resources and cave potentials using thermal infrared image and terrain characteristics in semi-arid regions of Iran

    Science.gov (United States)

    Jalali, Nader; Saghafian, Bahram; Imanov, Farda; Museyyibov, Museyyib

    2009-12-01

    Shallow karst water resources and caves may influence land surface temperatures due to cold transfer property of rocks and evaporation from buried karst. The objective of this research was to develop a method for recognition of karst areas based on evaluating the surface characteristics that manifest itself by low land surface temperature in the satellite images. Investigation of thermal ETM + image of the study region in Iran showed that parts of carbonate rocks that bear karst water are relatively cooler compared to areas with similar terrain conditions. Relational modeling provided useful information on spatial distribution of areas that have the potential to hold karst water resources and/or caves. Further inspection of ASTER images, along with geotechnical, geophysical and geological field surveys verified the approach. Significant correlation was found between electrical resistivity and thermal band values. The method may be used as a primary exploratory tool for shallow karst water explorations in similar areas.

  1. Water use and physiology of the riparian tree species Eucalyptus victrix in the semi-arid Pilbara region of Western Australia

    Science.gov (United States)

    Pfautsch, S.; Keitel, C.; Adams, M. A.; Turnbull, T.

    2009-04-01

    We examined the water use and physiology of trees growing in a riparian community within the seasonally arid Pilbara region of north-western Australia. This region is arid during the winter months, but monsoonal during summer (November to April). Maximum monthly mean temperatures in summer exceed 40 °C and are c. 25 °C during the winter months. The Millstream study site is located on a section of the Fortescue River system along the base of the Chichester Range c. 100km south of Karratha. This system creates a unique landscape in the Pilbara as it forms several large permanent pools. These pools are maintained by springs from an aquifer beneath the alluvial plain. The groundwater from this aquifer is used as a public water supply for towns in the west Pilbara but industrial development and a growing population will place greater demand on this aquifer. Changes to the local hydrology may have dramatic effects on the local plant community, dominated variously by stands of Eucalyptus victrix (Coolibah) and Eucalyptus camaldulensis (River red gum). This study seeks to understand the dependence of the Millstream riparian ecosystem on the height of the aquifer and to characterise the water use and physiology of Eucalyptus victrix. We used a number of techniques to determine the hydraulic and photosynthetic status of the tree canopy, including isotope, sap flow, water-potential and gas exchange measurements. Initial results from this study show: a) Soil water d18O and d2H is strongly enriched towards the surface, which coincides with a strong increase in salinity. The water source accessed by these trees has been identified by d18O and d2H analysis of xylem water. d18O and d2H were additionally analysed in atmospheric and leaf water pools. b) Sap flow in Coolibah trees shows a unique pattern of sharp early morning rise to a plateau maintained throughout the hottest part of the day, followed by a sharp decline in flow late in the afternoon. c) Leaf water potential

  2. Using a Modified Soil-Plant-Atmosphere Scheme (MSPAS) to Simulate the Interaction between Land Surface Processes and Atmospheric Boundary Layer in Semi-Arid Regions

    Institute of Scientific and Technical Information of China (English)

    刘树华; 乐旭; 胡非; 刘辉志

    2004-01-01

    This paper uses a Modified Soil-Plant-Atmosphere Scheme (MSPAS) to study the interaction between land surface and atmospheric boundary layer processes. The scheme is composed of two main parts:atmospheric boundary layer processes and land surface processes. Compared with SiB and BATS, which are famous for their detailed parameterizations of physical variables, this simplified model is more convenient and saves much more computation time. Though simple, the feasibility of the model is well proved in this paper. The numerical simulation results from MSPAS show good agreement with reality. The scheme is used to obtain reasonable simulations for diurnal variations of heat balance, potential temperature of boundary layer, and wind field, and spatial distributions of temperature, specific humidity, vertical velocity,turbulence kinetic energy, and turbulence exchange coefficient over desert and oasis. In addition, MSPAS is used to simulate the interaction between desert and oasis at night, and again it obtains reasonable results.This indicates that MSPAS can be used to study the interaction between land surface processes and the atmospheric boundary layer over various underlying surfaces and can be extended for regional climate and numerical weather prediction study.

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

    Directory of Open Access Journals (Sweden)

    Palacio-Núñez, J.

    2007-06-01

    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.

  4. Quantifying macropore recharge: Examples from a semi-arid area

    Science.gov (United States)

    Wood, W.W.; Rainwater, K.A.; Thompson, D.B.

    1997-01-01

    The purpose of this paper is to illustrate the significantly increased resolution of determining macropore recharge by combining physical, chemical, and isotopic methods of analysis. Techniques for quantifying macropore recharge were developed for both small-scale (1 to 10 km2) and regional-scale areas in and semi-arid areas. The Southern High Plains region of Texas and New Mexico was used as a representative field site to test these methods. Macropore recharge in small-scale areas is considered to be the difference between total recharge through floors of topographically dosed basins and interstitial recharge through the same area. On the regional scale, macropore recharge was considered to be the difference between regional average annual recharge and interstitial recharge measured in the unsaturated zone. Stable isotopic composition of ground water and precipitation was used us an independent estimate of macropore recharge on the regional scale. Results of this analysis suggest that in the Southern High Plains recharge flux through macropores is between 60 and 80 percent of the total 11 mm/y. Between 15 and 35 percent of the recharge occurs by interstitial recharge through the basin floors. Approximately 5 percent of the total recharge occurs as either interstitial or matrix recharge between the basin floors, representing approximately 95 percent of the area. The approach is applicable to other arid and semi-arid areas that focus rainfall into depressions or valleys.The purpose of this paper is to illustrate the significantly increased resolution of determining macropore recharge by combining physical, chemical, and isotopic methods of analysis. Techniques for quantifying macropore recharge were developed for both small-scale (1 to 10 km2) and regional-scale areas in arid and semi-arid areas. The Southern High Plains region of Texas and New Mexico was used as a representative field site to test these methods. Macropore recharge in small-scale areas is considered

  5. Irrigated plantations and their effect on energy fluxes in a semi-arid region of Israel - a validated 3-D model simulation

    Science.gov (United States)

    Branch, O.; Warrach-Sagi, K.; Wulfmeyer, V.; Cohen, S.

    2013-11-01

    A large irrigated biomass plantation was simulated in an arid region of Israel within the WRF-NOAH coupled atmospheric/land surface model in order to assess land surface atmosphere feedbacks. Simulations were carried out for the 2012 summer season (JJA). The irrigated plantations were simulated by prescribing tailored land surface and soil/plant parameters, and by implementing a newly devised, controllable sub-surface irrigation scheme within NOAH. Two model cases studies were considered and compared - Impact and Control. Impact simulates a hypothetical 10 km × 10 km irrigated plantation. Control represents a baseline and uses the existing land surface data, where the predominant land surface type in the area is bare desert soil. Central to the study is model validation against observations collected for the study over the same period. Surface meteorological and soil observations were made at a desert site and from a 400 ha Simmondsia chinensis (Jojoba) plantation. Control was validated with data from the desert, and Impact from the Jojoba. Finally, estimations were made of the energy balance, applying two Penman-Monteith based methods along with observed meteorological data. These estimations were compared with simulated energy fluxes. Control simulates the daytime desert surface 2 m air temperatures (T2) with less than 0.2 °C deviation and the vapour pressure deficit (VPD) to within 0.25 hPa. Desert wind speed (U) is simulated to within 0.5 m s-1 and the net surface radiation (Rn) to 25 W m-2. Soil heat flux (G) is not so accurately simulated by Control (up to 30 W m-2 deviation) and 5 cm soil temperatures (ST5) are simulated to within 1.5 °C. Impact simulates daytime T2 over irrigated vegetation to within 1-1.5 °C, the VPD to 0.5 hPa, Rn to 50 W m-2 and ST5 to within 2 °C. Simulated Impact G deviates up to 40 W m-2, highlighting a need for re-parameterisation or better soil classification, but the overall contribution to the energy balance is small (5

  6. Decision support for on-farm water management and long-term agricultural sustainability in a semi-arid region of India

    Science.gov (United States)

    Singh, Ajay

    2010-09-01

    SummaryThe long-term success of irrigated agriculture for sustainable crop production in India depends largely on the careful management of land and water resources. Currently, some serious environmental problems of waterlogging and soil salinization are burgeoning in parts of Haryana State of India; half a million hectare area of the State is already waterlogged. Poor irrigation and drainage management and inadequate exploitation of saline ground water are the main factors responsible for this phenomenon. In order to prevent further degradation and to maintain the food production for the growing population, judicious use of natural resources is a must. A wide range of solutions could be considered to address the problems. But the effectiveness of all the solutions and their combinations cannot be verified with on-farm experiments. Simulation models by way of their predictive capability are often the only viable means of providing input to management decisions. These models can help to forecast the likely impacts of a particular alternative management strategy. In the present study a physical based one-dimensional simulation model SWASALT was employed to evaluate on-farm irrigation water management options. After successful calibration and validation with field experimentation data, several scenario building exercises have been conducted under different crop, soil and rainfall conditions. The water and salt balance component obtained for each simulation run were used to derive water management response indicators. The simulation study revealed that in most conditions, saline water of up to 7.5 dS/m can be used safely on long term basis for crop production. The simulation study further revealed that alternative use of canal and saline water had an edge over mix use. Several alternatives have been suggested for sustainable agricultural production in the region. The strategies suggested, if followed, would lend sustainability to the agricultural production besides

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

    Science.gov (United States)

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

    2016-02-01

    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.

  8. Richness and diversity of Leguminosae in an altitudinal gradient in the tropical semi-arid zone of Brazil

    Institute of Scientific and Technical Information of China (English)

    Jacira R.LIMA; Vidal F.MANSANO; Francisca S.ARA(U)JO

    2012-01-01

    Many studies are based on the premise that,on a local scale,diversity is the result of ecological processes,whereas on a regional scale factors such as the topography,geology,hydrology,and historical and evolutionary events would influence this control.The Baturité Mountain Range (Ceará state),located in the Brazilian semi-arid zone,is considered an area of extreme importance for conservation with its vegetation varying with the altitude and slope (windward vs.leeward).On the windward (wet) slope,rainforest dominates,whereas the leeward (dry) slope is dominated by seasonal forests and thorny woodland.The aim of this study was to contribute to the knowledge of the patterns of richness and diversity of the family Leguminosae on a local scale (Baturité Mountain Range) as well as a regional scale (northeastern Brazil).The two slopes present quite distinct floras.The dry slope presents higher richness and diversity indices for Leguminosae than the wet slope.The highest diversity of Leguminosae in the dry areas did not corroborate the ideas of other studies carried out in neotropical forests (total flora) that the higher species richness was predicted for wet areas.The present study indicates that the historical and evolutionary processes influence the diversity patterns on a local scale (Baturité Mountain Range),as well as on a regional scale (Brazilian semi-arid).Our results reinforce the uniqueness of each portion of this area and its importance for conservation.

  9. Rainwater harvesting in arid and semi-arid zones (repr. 1997)

    NARCIS (Netherlands)

    Boers, Th.M.

    1994-01-01

    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 systems, and this dissertation deals

  10. 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.

    2006-01-01

    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 evap

  11. An overview of biodegradation of LNAPLs in coastal (semi)-arid environment

    NARCIS (Netherlands)

    Yadav, B.K.; Hassanizadeh, S.M.

    2011-01-01

    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 o

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

    Science.gov (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.

    2000-01-01

    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.

  13. Drought Characteristics Analyzing Method Based on Palmer Index in Northeast Semi-arid Region%东北半干旱地区Palmer干旱指数特征分析方法

    Institute of Scientific and Technical Information of China (English)

    李晓辉; 杨勇; 任传友

    2013-01-01

    Palmer Index can more accurately describe the intensity of drought,but when each month or season rainfall is not balanced,the condition of disaster will be weakened because the index integrates the surplus or shortage of rainfall in each month.The improved method of combining Malikov criterion and the Palmer index to analyze the characteristics of drought is introduced.Sixty years' meteorological data,including daily precipitation,temperature,etc,from 1952 to 2011,in northeast semi-arid regionChaoyang of Liaoning province were used to analyze drought characteristics.The results show that the proposed analytic method is correct and objective.It complements the judgment of Palmer analysis by discriminating the drought characteristics of the 5 years including 1959,1960,etc.among the 60 years' experimental data from the normal years according to Palmer alone,and it can objectively reflect the actual drought features.%Palmer指标可以较准确地描述干旱的强度,但当各个月份或季节降雨量不均衡时,由于干旱指数综合了各个月份降水的盈余或短缺,使得其弱化了灾情,通过改进方法,引入了马利科夫判据与Palmer指数结合的方法分析干旱特征.分析利用东北半干旱地区辽宁省朝阳地区1952-2011年期间60年的日降水量、气温等气象数据,进行干旱特征分析,结果表明:引入马利科夫判据与Palmer指数结合的方法分析干旱特征方法正确、客观.该方法进一步对Palmer指数分析结果补充判断,有效辨别出60年的试验数据中1959,1960,1963,1993,1999年5个年份原始判定为正常旱情的年份,能够客观地反映实际旱情特征.

  14. Calibration,validation and application of the CERES-Maize model for sprinkled maize in the semi-arid region%半干旱地区喷灌玉米CERES-Maize模型率定验证及应用

    Institute of Scientific and Technical Information of China (English)

    温江丽; 李久生

    2015-01-01

    作物模型是确定水氮优化管理措施的有力工具,而模型的率定和验证是模拟结果推广应用的前提。利用内蒙古半干旱区2012、2013年的大型喷灌机条件下玉米水氮充足处理对 CERES-Maize模型的作物品种参数进行率定,其他不同水氮处理进行验证,并应用模型模拟了不同降雨年型下灌水施肥方案对作物产量和氮素淋失量的影响。模型验证结果表明,CERES-Maize模型可以较好地描述该地区不同水氮处理条件下玉米叶面积指数(LAI)在生育期内的变化过程。中、高灌水量处理玉米生育期内 LAI 的模拟精度(标准均方根误差 nRMSE=23.0%~37.7%,一致性指数d=0.612~0.945)优于水分亏缺较严重的处理(nRMSE=31.8%~60.6%,d=0.501~0.878)。产量和收获期干物质质量模拟值与实测值之间的相对误差变化范围为0.1%~17.7%,nRMSE变化范围为7.6%~8.7%,d变化范围为0.758~0.791,吻合程度为优。CERES-Maize模型可用以优化喷灌水氮管理措施。不同降雨年型玉米最优灌水方案为:枯水年灌水次数为10次,灌溉定额为292 mm;平水年和丰水年灌水次数分别为8次和6次,灌溉定额分别为191 mm和95 mm。不同降雨年型最优施肥方案为:基肥的施入量为40 kg/hm2,拔节期和抽穗期的施入量均为60 kg/hm2。优化水氮管理措施不仅能够获得较高的玉米产量,还能减少氮素淋失。%Crop model is an efficient tool to determine best management practices of irrigation and fertiliza⁃tion. The calibration and validation of the model is fundamentally important for applying the crop model. In this study,the data obtained from two years (2012 and 2013) experiments of maize conducted in the semi-arid region with varying irrigation and nitrogen levels under sprinkler irrigation were used to calibrate and validate the CERES-Maize model. Then the calibrated and verified model was used to evaluate the ef⁃fect of

  15. Nebkha patterns in semi-arid environments

    Science.gov (United States)

    Nield, J. M.; Gillies, J. A.; Nickling, W. G.

    2014-12-01

    In semi-arid supply-limited, environments, nehbka dunes typically form through ecogeomorphic feedbacks. The size, shape and orientation of these dunes are controlled by the interactions between vegetation growth and aeolian sedimentations processes. Once established, these dune patterns modify sediment transport and often form streets of bare surfaces between dune corridors. We examine typical dune and vegetation patterns that form with varying amounts of sediment availability and nebkha maturity at Jornada in the Chihuahuan Desert, New Mexico, USA using terrestrial laser scanning (TLS) to separate the plant and sand elements. Manual and automated TLS shrub height extractions compare well at all sites (p = 0.48-0.94) enabling the quantification of both solid and plant roughness element components in three dimensions. We find that there is a switch in orientation of the dune elements with respect to dominant wind direction from perpendicular to parallel as the landscape develops from an incipient to mature configuration and mesquite-nebkha streets are enhanced. As the nebkha dunes develop the surface coverage of bare sand increases and dune surfaces exceed the size of their companion shrubs. Roughness density also increases at the mature dune site. Individual shrub orientations remain similar at each site, but nebkhas typically host multiple shrub crowns at the mature site. Over a two year period up to 20 cm of erosion was measured on the upwind faces of the mature nebkha dunes, in agreement with the dominant annual wind direction. However, deposition patterns were more diffuse and influenced by the vegetation patterns. This study highlights the importance of ecogeomorphic interactions in shaping nebkha landscape patterns.

  16. 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

    1999-08-01

    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

  17. Understanding cropping systems in the semi-arid environments of Zimbabwe: options for soil fertility management

    OpenAIRE

    Ncube, B.

    2007-01-01

    African smallholder farmers face perennial food shortages due to low crop yields. The major cause of poor crop yields is soil fertility decline. The diversity of sites and soils between African farming systems isgreat,therefore strategies to solve soil fertility problems should suit the opportunities and problems encountered in the different climatic regions. This thesis characterizes the semi-arid regions of south-western Zimbabwe and explores some of the strategies that can be used to provi...

  18. 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

    2012-01-01

    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

  19. Impacts of Fertilizer on Avena sativa Growth in High and Semi-arid Regions%施肥量对高寒半干旱地区燕麦生长的影响

    Institute of Scientific and Technical Information of China (English)

    罗振堂; 郭连云; 侯万红; 王晓兰

    2011-01-01

    [目的]研究施肥量对高寒半干旱地区燕麦生长的影响.[方法]2009年在青海省共和盆地木格滩高寒半干旱地区种植燕麦,共设4个处理.对不同处理下燕麦的株高、分蘖数、主穗长、小穗数、穗粒数、千粒重、产量进行比较.[结果]燕麦的出苗、分蘖、拔节、抽穗、开花期各处理一致,结籽期各处理相差2~6d,成熟期各处理相差13 d.不同施肥处理对燕麦生长有明显的影响,株高、分蘖数、主穗长、小稳数、稳粒数随施肥量的增加而增大,千粒重则相反.各处理燕麦草籽产量和草捆产量变化一致,表现为施肥量与产量呈非正比关系;各处理燕麦收后茬地产量和生物产量变化相同,呈随施肥量的增多产量相应增大的趋势.[结论]为提供优质、高产量的饲草提供技术依据和实践指导.%[Objective] The aim was to study impacts of fertilizer on Avena sativa growth in high and semi-arid regions. [ Method ] The experi ment was conducted at the Mugetan in the Gonghe Basin, Qinghai Province,four controlled treatments were established. Observation items in cluded plant height, tiller numbers, length of main fringe, spikelet numbers, grain numbers of spikelets, 1 000-grain weight, production. [Results] Seedling emergence, tillering, stem elongation, heading and flowering showed no differences among the four treatment, but matu ring periods were changed significantly. Initially, seed setting periods showed differences varying from 2 days to 6 days, but later maturing pe riods showed differences that even reached 13 days. Fertilizer had significant impacts on Avena satwa development. If more fertilizer was added to Avena sativa, plant height, tiller numbers, length of main fringe, spikelet numbers, and grain numbers of spikelet would be increased. Seed and grass production changed in the same step, but their changes were not in a direct proportion with feritilizer amount. The more fertilizere was

  20. Mapeamento de áreas aluvionares no semiárido brasileiro por meio de dados colaterais e imagens orbitais Mapping alluvial areas in semi-arid region of Brazil through collateral data and satellite images

    Directory of Open Access Journals (Sweden)

    Helio L. Lopes

    2013-07-01

    Full Text Available A região semiárida do Brasil possui grande potencial para armazenamento de água em áreas aluvionares, podendo potencializar a pequena agricultura. Verifica-se a necessidade de uma metodologia para mapeamento dessas áreas, com o objetivo de futuros estudos in loco para implantação de barragens subterrâneas e manejo correto dos solos aluvionares. Neste sentido, objetivou-se a aplicação de imagens Landsat- Mapeador Temático 5 em conjunto com dados colaterais, como a rede de drenagem, mapa de classes de solo e mapa de relevo para auxiliar na classificação de terraços aluviais. Teve-se, como área de estudo, a bacia do Rio Pajeú, no sertão do estado de Pernambuco. Buscou-se também, por meio de dados SRTM (Shuttle Radar Topography Mission, a avaliação topográfica das áreas classificadas. Verifica-se que a utilização única de dados orbitais traz classificação incongruente mas com a inserção de dados colaterais é possível obter melhores resultados na classificação. A rede de drenagem é fundamental no mascaramento de classificações espúrias. Quando procede à análise topográfica por meio de dados do SRTM das áreas classificadas como terraços aluvionares, observa-se a inconsistência desses dados.The semi-arid region of Brazil has great potential for storing water in alluvial areas, and may give support to small-scale family farming. There is a need to establish a methodology for mapping these areas with the objective of future studies to implement underground dams and suitable management of the soils that occur on alluvial terraces. In this way, the aim of this study was to apply Landsat-Thematic Mapper images together with collateral data such as the drainage network, map of soil classes and elevation data to assist in the classification of alluvial terraces. The study area was Pajeú River basin located in the 'Caatinga' ecosystem of the Pernambuco state. Topographic assessment of the alluvial areas was done by

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

    Energy Technology Data Exchange (ETDEWEB)

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

    1997-12-31

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

  2. Conservation and restoration of degraded ecosystems in arid and semi-arid areas of northwest China

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    In "West Development" of China, one of the most important activities is the Natural Forest Protection Program, designed to swiftly convert the focus of management and utilization of the natural forests from a timber orientation towards forest conservation, sustainable management and environmental protection. The project covered almost all the arid and semi-arid regions in Northwest region. Accompanying this great campaign this paper studied the conservation and restoration model of degraded ecosystems in arid and semi-arid lands in Northwest China. The past practices have resulted in considerably natural forest degradation and loss through land conversion (primarily for agriculture), over-harvesting, inadequate reforestation and lack of protection. The consequences have been the loss of soil and water resources, diminished timber production capacity on a sustainable basis, and environmental losses. This paper applied Aronson's restoration model and proposed the conservation, restoration, re-allocation and preservation program for the implementation of environmental improvement and natural forest conservation.

  3. Using NDVI to measure precipitation in semi-arid landscapes

    Science.gov (United States)

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

    2016-01-01

    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.

  4. Adaptation to drought in arid and semi-arid environments: Case of the Zambezi Valley, Zimbabwe

    OpenAIRE

    Emmanuel Mavhura; Desmond Manatsa; Terence Mushore

    2015-01-01

    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 exami...

  5. Feeding behavior and physiological responses of sheep grazing in the semi-arid

    Directory of Open Access Journals (Sweden)

    Carolyny Batista Lima

    2014-01-01

    Full Text Available Sheep farming is an important social and economic support for the population living in semi-arid zones. These climatic conditions in these regions - a high radiant heat load, especially - may require adjustments in physiology and behavior of the animal to enable their survival. The increased respiratory rate and rectal temperature, with seeking behavioral patterns reduced grazing time and increased idle time are recurrent in the literature as the main physiological and behavioral responses of sheep grazing in high radiant heat load environments. The presence of shadow, natural or artificial, can encourage and facilitate thermolysis physiological adjustments sheep without harm, predominantly, your metabolism. Thus, the objective of compiling information on the main patterns of behavior, as well as major physiological responses of sheep grazing in semi-arid zones.

  6. EMISSION OF NITROUS OXIDE AND CARBON DIOXIDE FROM SEMI-ARID TROPICAL SOILS IN CHIAPAS MÉXICO

    OpenAIRE

    2010-01-01

    The semi-arid region of Chiapas is dominated by N2 -fixing shrubs, e.g., Acacia angustissima. Urea-fertilized soil samples under maize were collected from areas covered and uncovered by A. angustissima in different seasons and N2O and CO2 emissions were monitored. The objective of this study was to determine the effects of urea and of the rainy and dry season on gas emissions from semi-arid soil under laboratory conditions. Urea and soil use had no effect on CO2 production. Nitrons oxide emis...

  7. 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

    2010-12-01

    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

  8. 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.

  9. Modeling carbon cycle dynamics and response to drought in semi-arid ecosystems

    Science.gov (United States)

    Hilton, T. W.; Fox, A. M.; Krofcheck, D. J.; Litvak, M. E.

    2012-12-01

    The southwestern United States is presently experiencing a multi-year drought. Though the carbon uptake per unit area of the semi-arid biomes in this region is smaller than that of more temperate biomes, these biomes cover roughly 40 percent of the world's land surface, and thus make a significant contribution to the global terrestrial biological carbon cycle. Here we test the ability of two land surface model structures to diagnose the carbon cycle dynamics of semi-arid landscapes during the ongoing extreme drought. We use the New Mexico Elevation Gradient (NMEG) as a testbed for these modeling experiments. The NMEG comprises eight eddy covariance towers observing ecosystems ranging from desert grassland ( 1600 m elevation) to alpine mixed coniferous forest ( 3000 m elevation). During the drought the ecosystems observed by these towers saw their annual net carbon uptake decline between 33 and 100 percent (50 to 150 gC m^{-2} year^{-1}), with two of the eight sites becoming net sources of carbon to the atmosphere and one transitioning from a net carbon sink to carbon-neutral. We parametrize a simple light-use efficiency (LUE)-based model (Vegetation Photosynthesis and Respiration Model, VPRM) and a complex model which simulates many land surface processes (Community Land Model, CLM). We explore the capacity of both models to diagnose the terrestrial carbon cycle in semi-arid biomes where water availability is highly episodic.

  10. 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.

  11. Time Profile of Three Semi-Arid Ecosystems in Africa

    Science.gov (United States)

    Anyamba, A.; Damoah, R.; Small, J. L.; Tucker, C. J.

    2015-12-01

    We examine the spatio-temporal variability of rainfall and satellite derived-vegetation index of three endorheic semi-arid ecosystems in Africa: Lake Chad (in the Sahel region), Okavango and Etosha (Southern Africa) to infer the nature and trends of the variability during the satellite data instrumental record. We utilize African Rainfall Climatology Precipitation Estimates (1983-2014) and Normalized Difference Vegetation Index (NDVI) derived from the Advanced Very High Resolution Radiometer (AVHRR: 1981-2014) and Moderate Resolution Imaging Spectroradiometer (MODIS: 2001:2014) to examine the aspects of the annual cycle and interannual variability using both time series plots and time-space diagrams. With respect to Lake Chad region, the first two decades of the series (1981-2000) show predominantly dryer than long-term average conditions with the periods 1989, 1992 and 1996/1997 as the signature drought periods coinciding with the desiccation of the Sahel region during the 1980s to early 1990s decades. The period 2000 to present is dominated by above average rainfall and NDVI with 2003, 2007 and 2012 being the most pronounced wet/greener years. The southern African ecosystems (Okavango and Etosha) show more or less a similar temporal pattern to that of Lake Chad basin, however, the wet periods are more amplified and persistent especially 2000, 2006, 2010 and 2014, with corresponding above average NDVI departures. The amplified nature of wet and dry periods present in the southern African ecosystem time series are consistent with the El Niño Southern Oscillation teleconnection patterns. Overall these three ecosystems serve as detectable fingerprints of changing climate conditions and ecosystems in these arid regions.

  12. 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.

    2012-01-01

    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 effe

  13. Ocorrência de ectoparasitos em avestruzes (Struthio camelus criadas no semi-árido baiano Occurence of ectoparasites in ostriches (Struthio camelus reared in semi-arid region of Bahia

    Directory of Open Access Journals (Sweden)

    Maria Ângela O. Almeida

    2008-09-01

    Full Text Available No período de maio a agosto de 2005, foram visitados 19 planteis de avestruzes na região semi-árida do município de Irecê, Bahia, objetivando identificar os ectoparasitos. As aves, predominantemente da raça "African Black", eram criadas em sistema intensivo e distribuídas, por faixa etária, em colônias, trio, casal ou creche. Durante a inspeção das aves, as plumas colhidas aleatoriamente, de várias regiões do corpo, foram acondicionadas em sacos plásticos e as larvas, colhidas das miíases, em álcool etílico a 70%. Em 74% (14/19 e 47% (04/19 dos plantéis encontravam-se avestruzes infestadas, respectivamente, pelas espécies Struthiopterolichus bicaudatus e Struthiolipeurus rheae. Somente em um plantel (5,3% foi encontrado um animal parasitado por larvas de Cochliomyia hominivorax.In the period of May to August of 2005, 19 ostrich's farms were visited in the semi-arid area of the Irecê, Bahia, in order to describe the ectoparasites. The African Black ostriches were reared in intensive system, and distributed for age group, in colonies, trio, couple or crèche. In each farm, after visually inspection of the ostrich, the feathers were taken in several areas of the body and were kept in plastic bags. The screwworms found were collected and stored in 70% ethanol. In 74% (14/19 and 47% (04/19 of the flocks were found ostriches infested, respectively, for the Struthiopterolichus bicaudatus (acari and Struthiolipeurus rheae (mallophaga. In only one flock (5.3% it was found an animal with Cochliomyia hominivorax larvae.

  14. 干旱半干旱地区藓结皮人工培养研究进展%A Review on the Studies of Moss Crust Artificial Cultivation in Arid and Semi-arid Region

    Institute of Scientific and Technical Information of China (English)

    王显蓉; 赵允格; 王媛

    2014-01-01

    In arid and semi-arid areas,moss crust play important ecological roles,such as improving soil resistance to wind and water erosion and enhancing soil fertility.In recent years,many studies have focused on artificial culture of moss crusts and its application in desertification control.This paper reviewed the research status and achievements on artificial moss crust cultivation in recent decades from the the aspects of reproductive biology,characteristics of growth and development of mosses,factors that affect the formation of moss crust and maintenance ability.Researches demonstrated that moss crusts could be successfully constructed in indoor and outdoor environment.However,this kind of moss crust performs poorly in maintenance ability.The majority of research for factors that affect the formation of moss crust was conducted in indoor environment,the influence mechanism in outdoor was not entirely clear.The research should be focused on how to combine the indoor training methods with the field methods,and to cultivate the moss crusts successfully in a fast and effective way.%在干旱半干旱地区,以藓类植物为优势物种的生物结皮,在抗风蚀、水蚀及增强土壤肥力等方面发挥着重要的作用.近年来随着人们对干旱半干旱地区生态环境的重视,藓结皮人工培养及其在土壤沙漠化防控方面的应用备受关注.从藓类植物的繁殖生物学、生长发育特点、藓结皮形成的影响因素及后期维持能力等方面综述了藓结皮人工培养的研究现状及主要进展,研究表明在室内和野外环境可成功构建藓结皮,然而其后期维持能力较差;藓结皮形成影响因素的研究多于室内环境下完成,野外环境下影响因素研究少见.将室内和野外培养方法相互结合,快速有效的培养藓结皮,是未来研究的重点.

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

    KAUST Repository

    Yadav, Brijesh Kumar

    2011-02-22

    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

  16. Characteristics of black carbon aerosol and carbonaceous gases and their emission sources in semi-arid region%半干旱地区黑碳气溶胶和含碳气体特征及来源

    Institute of Scientific and Technical Information of China (English)

    陈霖; 张镭; 张磊; 曹贤洁; 黄建平; 张武; 张北斗

    2012-01-01

    Adopting observational data of multi angle absorption photometer (MAAP-5012) and the gas composition mixing ratio data of CO and CO2 of Semi-Arid Climate Observatory and Laboratory (SACOL) from September 2009 to June 2010, the characteristics and effects of source of black carbon aerosol and carbon gas in semi-arid areas of Northwest China, and the types of emissions which have impact on the concentration of black carbon were analyzed. The result indicated that average concentrations of BC, CO and CO2 were 1.75ug/m3, 601.71×10-9and 387.78x10-6, respectively. Hybrid Single Particle Lagrangian Integrated model (HYSPLIT-4) was used to distinguish the flow areas from eastern and western of the observation station. When the airstreams came from the east, the concentrations of BC, CO, CO2 were 1.38ng/m3, 462.79× 10-9 and 383.03x 10-6, respectively. When the airstreams came from the west, the concentrations of BC, CO, CO2 are 2.2ug/m3, 768.38×10-9 and 393.47×10-6, respectively. Taking the clustering analysis on the origin places of the airstreams in the height of 500m, 1500m and 3000m, get the results that when the airstreams of different height flow respective from the Middle East, Central Asia, and Europe, the concentrations of BC, CO, CO2 were higher and the values of ABC/ACO, ACO/ACO2 were larger, indicating the efficiency of fuel combustion was lower; when the airstreams transmits from Central and Northern China, the concentrations of BC, CO, CO2 were lower, and the values of ABC/ACO, ACO/ACO, were smaller, indicating the efficiency of fuel combustion is higher.%利用2009年9月~2010年6月兰州大学半干旱气候与环境观测站(SACOL)多角度吸收分光光度计(MAAP-5012)观测数据、CO和CO2气体成分混合比数据,分析了西北半干旱地区黑碳气溶胶和含碳气体特征、影响源地,以及影响黑碳浓度的捧放物类型.结果表明BC、CO、CO2平均浓度分别为1.75μg/m3、601.71×10-9、387.78×10-6.利用后向轨迹

  17. Role of radiatively forced temperature changes in enhanced semi-arid warming over East Asia

    Directory of Open Access Journals (Sweden)

    X. Guan

    2015-08-01

    Full Text Available 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.

  18. 半干旱区近地层动量热通量计算%Analysis of momentum and sensible heat fluxes in surface layer in the semi-arid regions

    Institute of Scientific and Technical Information of China (English)

    鲍婧; 张镭; 张燕; 史晋森

    2009-01-01

    By using the tower observation data on wind, temperature, and humidity in the semi-arid climate and environment observatory of Lanzhou University from Dec 2006 to Feb 2007, the friction velocity, friction temperature, turbulent momentum flux and sensible heat flux were analyzed with the gradient calculation method; then the flux value was compared with the result of the eddy-covariance flux measurement in Feb 2007. The results show that the turbulent momentum flux and sensible heat flux have a close connection with the atmospheric stability, and they both decrease with decrease of the stability. They all have obvious diurnal variation, the biggest appears at noon and the smallest at night. The momentum fluxes are always downward transfering regardless of the stability, but sensible heat fluxes are upward transfering at daytime, and downward transfering at night. The monthly mean momentum flux and sensible heat flux are the smallest in Dec, the largest in Feb, and the monthly mean momentum flux is far less than that of the sensible heat flux. In Feb, the slope of turbulent momentum flux scatter diagram is 1.096, and correlation coefficient is 0.761; the slope of sensible heat flux scatter diagram is 1.015, and correlation coefficient is 0.957.%利用兰州大学半干旱气候与环境观测站2006年12月-2007年2月铁塔观测所得的7层风、温、湿资料,采用梯度法计算了摩擦速度、摩擦温度、湍流动量通量和感热通量,并将2007年2月的通量计算值与开路涡度协方差系统观测值进行比较.结果表明:动量通昔和感热通量与稳定度有密切关系.均随稳定度的增加而减小.动量通量和感热通量均有明显的日变化,中午时段最大,夜晚最小.动量通昔无论在何种稳定度条件下均是由上向下输送;感热通量白天均是由下向上输送,夜间均是由上向下输送.在冬季,动量通量和感热通量的月平均值都是在12月最小,在2月最大,且动量通量

  19. Application of spatially varying storage capacity model for runoff parameterization in semi-arid catchment

    Institute of Scientific and Technical Information of China (English)

    Li-liang REN; Gui-zuo WANG; Fang LU; Tian-fang FANG

    2009-01-01

    This paper introduces the method of designation of water storage capacity for each grid cell within a catchment, which considers topography, vegetation and soil synthetically. For the purpose of hydrological process simulation in semi-arid regions, a spatially varying storage capacity (VSC) model was developed based on the spatial distribution of water storage capacity and the vertical hybrid runoff mechanism. To verify the applicability of the VSC model, both the VSC model and a hybrid runoff model were used to simulate daily runoff processes in the catchment upstream of the Dianzi hydrological station from 1973 to 1979. The results showed that the annual average Nash-Sutcliffe coefficient was 0.80 for the VSC model, and only 0.67 for the hybrid runoff model. The higher annual average Nash-Sutcliffe coefficient of the VSC model means that this hydrological model can better simulate daily runoff processes in semi-arid regions. Furthermore, as a distributed hydrological model, the VSC model can be applied in regional water resource management.

  20. Application of spatially varying storage capacity model for runoff parameterization in semi-arid catchment

    Directory of Open Access Journals (Sweden)

    Li-liang REN

    2009-06-01

    Full Text Available This paper introduces the method of designation of water storage capacity for each grid cell within a catchment, which considers topography, vegetation and soil synthetically. For the purpose of hydrological process simulation in semi-arid regions, a spatially varying storage capacity (VSC model was developed based on the spatial distribution of water storage capacity and the vertical hybrid runoff mechanism. To verify the applicability of the VSC model, both the VSC model and a hybrid runoff model were used to simulate daily runoff processes in the catchment upstream of the Dianzi hydrological station from 1973 to 1979. The results showed that the annual average Nash-Sutcliffe coefficient was 0.80 for the VSC model, and only 0.67 for the hybrid runoff model. The higher annual average Nash-Sutcliffe coefficient of the VSC model means that this hydrological model can better simulate daily runoff processes in semi-arid regions. Furthermore, as a distributed hydrological model, the VSC model can be applied in regional water resource management.

  1. Remote Sensing Parameterization of Land Surface Heat Fluxes over Arid and Semi-arid Areas

    Institute of Scientific and Technical Information of China (English)

    马耀明; 王介民; 黄荣辉; 卫国安; MassimoMENENTI; 苏中波; 胡泽勇; 高峰; 文军

    2003-01-01

    Dealing with the regional land surfaces heat fluxes over inhomogeneous land surfaces in arid and semi-arid areas is an important but not an easy issue. In this study, one parameterization method based on satellite remote sensing and field observations is proposed and tested for deriving the regional land surface heat fluxes over inhomogeneous landscapes. As a case study, the method is applied to the Dunhuang experimental area and the HEIFE (Heihe River Field Experiment, 1988-1994) area. The Dunhuang area is selected as a basic experimental area for the Chinese National Key Programme for Developing Basic Sciences: Research on the Formation Mecbanism and Prediction Theory of Severe Climate Disaster in China (G1998040900, 1999-2003). The four scenes of Landsat TM data used in this study are 3 June 2000,22 August 2000, and 29 January 2001 for the Dunhuang area and 9 July 1991 for the HEIFE area. The regional distributions of land surface variables, vegetation variables, and heat fluxes over inhomogeneous landscapes in arid and semi-arid areas are obtained in this study.

  2. Prática do aleitamento materno em comunidades rurais do semi-árido baiano The practice of maternal breast-feeding in rural communities of a semi-arid region of northeastern Brazil

    Directory of Open Access Journals (Sweden)

    Ana Marlúcia O. Assis

    1994-10-01

    Full Text Available Com o objetivo de conhecer p estabelecimento e duração do aleitamento materno total e exclusivo em comunidades rurais do Semi-Árido Baiano, Brasil, foram estudadas 226 crianças de O a 2 anos de idade, filhas de pequenos produtores rurais que vivem numa das regiões mais secas do nordeste brasileiro, de pobreza absoluta. Os dados referem-se a todas as crianças da família que à data do estudo tinham até 2 anos de idade. Os dados foram coletados por meio de formulários aplicados às mães ou responsáveis pelo menor, no período de 1988 a 1989. A tábua de vida foi o recurso estatístico utilizado para o cálculo da duração mediana do evento. Das 226 crianças que integraram o estudo, 91,6 iniciaram a amamentação ao peito. A duração mediana do aleitamento total foi de 90,28 dias e o aleitamento exclusivo apresentou duração mediana de 0,1 dia. Ainda que o estabelecimento da amamentação ao peito possa ser considerado alto, a duração mediana do aleitamento total foi extrememente curta, e o aleitamento exclusivo foi desprezível.A Research project in the establishment and duration of total and exclusive breast-feeding in rural communities of Cansação, BA, Brazil, is presented. It included 226 children, from zero to two years old, of families of peasants living on small-holdings in one of the driest and poorest regions of the Brazilian Northeast. The data were collected through questionnaires answered by mothers or any adult responsible for the child during 1988 and 1989. It relates to all children from these families who were two years of age at the time of the study. The survival time was the statistical method used to calculate the median duration of breast-feeding; 91.6% of the 226 children started to be breast-fed. This finding shows that the establishment of the breast-feeding was high. The median duration of total breast-feeding was of 90.28 days and exclusive breastfeeding presented a median duration of 0.1 day. Through

  3. Mediterranean semi-arid systems-sensitivity and adaptation

    Energy Technology Data Exchange (ETDEWEB)

    Lavee, H.; Sarah, P.

    2009-07-01

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

  4. ANTHELMINTIC RESISTANCE TO BENZIMIDAZOLE IN GASTROINTESTINAL NEMATODES FROM SMALL RUMINANTS OF SEMI-ARID BRAZILIAN NORTHEAST RESISTÊNCIA AOS ANTI-HELMÍNTICOS BENZIMIDAZÓIS EM NEMATÓIDES GASTRINTESTINAIS DE PEQUENOS RUMINANTES DO SEMIÁRIDO NORDESTINO BRASILEIRO

    Directory of Open Access Journals (Sweden)

    Ana Carolina Fonseca Lindoso Melo

    2009-04-01

    Full Text Available Resistance to benzimidazole anthelmintics is reported as an old and persistent problem in many parts of the world. Resistance development depends on the presence of resistance promoters and there are operational, genetic and bioecological factors. The objective of this work was to determine the prevalence of benzimidazole resistance and to study some variables associated with resistance development in small ruminant farms in the Brazilian northeastern semi-arid area. The work was accomplished in 25 sheep and goat farms in Limoeiro do Norte, Palhano, Jaguaruana, Itaiçaba, Aracati, Alto Santo, Morada Nova and Jaguaribe municipalities, in the state of Ceará, Brazil. The procedure used to detect anthelmintic resistant nematodes was the fecal egg count reduction test. In addition, a questionnaire about management practices, infrastructure, anthelmintic usage, flocks sanitary state and veterinary assistance was applied. Data were analyzed using RESO statistical program. The questionnaires were analyzed using Spearman correlation and the simple GLM. In sheep farms, the prevalence of benzimidazole resistance was 88% and in goat farms, it was 87.5%. In sheep and goats farms, Haemonchus spp was the most prevalent genus, followed by Trichostrongylus spp and Oesophagostomum spp. Among variables studied, treatment in the dry season was statistically significant (P = 0.03, pasture rotation was not significant (P = 0.17 but has a predictable value in resistance development.

    KEY WORDS: Associated factors, benzimidazole, Ceará, resistance development.
    A resistência a anti-helmínticos benzimidazóis é relatada como um antigo e persistente problema em diversas partes do mundo. O desenvolvimento da resistência depende da presença de promotores, os quais podem ser fatores operacionais, genéticos e bioecológicos. O objetivo do presente estudo foi determinar a prevalência da resistência a anti-helmínticos benzimidazóis e estudar algumas

  5. Produção e distribuição de biomassa de espécies arbóreas no semi-árido brasileiro Production and distribution of biomass of tree species in the Brazilian semi-arid area

    Directory of Open Access Journals (Sweden)

    Marcos Antônio Drumond

    2008-08-01

    Full Text Available Com o objetivo de avaliar a produção e distribuição de biomassa de algumas espécies arbóreas de múltiplo uso em condições de sequeiro do submédio do São Francisco, instalou-se um experimento no Campo Experimental da Caatinga da Embrapa Semi-Árido, Município de Petrolina, PE. Foram realizadas medições de altura e diâmetro à altura do peito (DAP de 16 árvores centrais, em três parcelas de cada espécie: Leucaena diversifolia, Caesalpinia velutina, Caesalpinia coriaria, Mimosa tenuiflora e Ateleia herbert-smithii. A biomassa foi estimada com base na árvore de altura média de cada parcela, avaliando-se, separadamente, cada componente (folhas, galhos, cascas e lenho. A biomassa nos diferentes componentes arbóreos das espécies foi distribuída na seguinte ordem: folhaThe objective of the study was to quantify the production and biomass distribution of some potential arboreal species of multiple uses, under dry land conditions, in the Brazilian Semi-arid. The study was developed in the Experimental Station of Caatinga, of Embrapa Semi-Árido, Petrolina-PE, Brazil. Plant height and diameter at breast height (DBH of 16 central trees of each plot, from three replicates, were measured. The following species were studied: Leucaena diversifolia, Caesalpinia velutina, Caesalpinia coriaria, Mimosa tenuiflora and Ateleia herbert-smithii. Biomass was estimated based on the medium height tree in each plot, evaluating each component separately: leaf, bark, branch, root and log, except for A. herbert-smithii that produced more leaf than bark. Total biomass production was superior for C. velutina (51.6 kg ha-1, followed by L. diversifolia (36.6 kg ha-1, A. herbert-smithii (26.4 kg ha-1, Caesalpinia coriaria (23.0 kg ha-1 and Mimosa tenuiflora (21.6 kg ha-1 However, leaf dry matter, the main potential component of forage species, was higher for C. velutina y A. herbert-smithii (2.8 kg ha-1 and C. coriaria (2.2 kg ha-1, L. diversifolia (2.0 kg

  6. Diurnal and Seasonal Variation of Surface Urban Cool and Heat Islands in the Semi-Arid City of Erbil, Iraq

    OpenAIRE

    Azad Rasul; Heiko Balzter; Claire Smith

    2016-01-01

    The influence of land surface temperature (LST) makes the near-surface layer of the troposphere a key driver of urban climate. This paper assesses the temporal formation of the daytime Surface Urban Cool Island (SUCI) and night-time Surface Urban Heat Island (SUHI) effect in Erbil, Iraq, situated in a semi-arid climate region. LST retrievals from the Moderate Resolution Imaging Spectroradiometer (MODIS) Aqua and Terra and MODIS Normalized Difference Vegetation Index (NDVI) from January 2003 t...

  7. C4 grasses prosper as carbon dioxide eliminates desiccation in warmed semi-arid grassland.

    Science.gov (United States)

    Morgan, Jack A; LeCain, Daniel R; Pendall, Elise; Blumenthal, Dana M; Kimball, Bruce A; Carrillo, Yolima; Williams, David G; Heisler-White, Jana; Dijkstra, Feike A; West, Mark

    2011-08-03

    Global warming is predicted to induce desiccation in many world regions through increases in evaporative demand. Rising CO(2) may counter that trend by improving plant water-use efficiency. However, it is not clear how important this CO(2)-enhanced water use efficiency might be in offsetting warming-induced desiccation because higher CO(2) also leads to higher plant biomass, and therefore greater transpirational surface. Furthermore, although warming is predicted to favour warm-season, C(4) grasses, rising CO(2) should favour C(3), or cool-season plants. Here we show in a semi-arid grassland that elevated CO(2) can completely reverse the desiccating effects of moderate warming. Although enrichment of air to 600 p.p.m.v. CO(2) increased soil water content (SWC), 1.5/3.0 °C day/night warming resulted in desiccation, such that combined CO(2) enrichment and warming had no effect on SWC relative to control plots. As predicted, elevated CO(2) favoured C(3) grasses and enhanced stand productivity, whereas warming favoured C(4) grasses. Combined warming and CO(2) enrichment stimulated above-ground growth of C(4) grasses in 2 of 3 years when soil moisture most limited plant productivity. The results indicate that in a warmer, CO(2)-enriched world, both SWC and productivity in semi-arid grasslands may be higher than previously expected.

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

    Directory of Open Access Journals (Sweden)

    Lin Deng

    2015-01-01

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

  9. The H2(18O) enrichment of the leaf water of tropic trees: comparison of species from the tropical rain forest and the semi-arid region in Brazil.

    Science.gov (United States)

    Zundel, G; Miekeley, W; Grisi, B M; Förstel, H

    1978-08-10

    The H2(18O) enrichment, delta, in the water of leaves from four Brazilian trees, was studied. In all trees the leaf water showed a periodic variation in delta, with a maximum in the early afternoon and a minimum around 6 a.m. In general delta was found to be either higher or lower than the stationary enrichment which is supposed to depend only on the relative atmospheric humidity. This effect is due to the slow response of the system to variations of the humidity. For a special case, where steady-state conditions could be anticipated, the kinetic enrichment was obtained to 20 +/- 3%, which agrees with theoretical predictions.

  10. 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

    2010-06-01

    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

  11. Detecção de anticorpos para Anaplasma sp. em pequenos ruminantes no semi-árido do estado de Pernambuco, Brasil Detection of antibodies against Anaplasma sp. in small ruminants from the semi-arid region against Pernambuco State, Brazil

    Directory of Open Access Journals (Sweden)

    Rafael A. N. Ramos

    2008-06-01

    Full Text Available Neste trabalho é descrita a detecção de anticorpos para Anaplasma sp. em caprinos e ovinos da região do semi-árido do Estado de Pernambuco, Brasil, utilizando-se um ensaio de imunoadsorção enzimática baseado em MSP5 recombinante de Anaplasma marginale. Foram analisados soros de 243 caprinos e 68 ovinos provenientes do município de Ibimirim, e observadas freqüências de anticorpos de 11,93% (29/243 e 16,17% (11/68 para caprinos e ovinos, respectivamente. A importância epidemiológica dos achados foi discutida.This paper reports the detection of antibodies against Anaplasma sp. in goats and sheep from the semi-arid region from Pernambuco State, Brazil, using an enzyme-linked immunosorbent assay with recombinant MSP5 of Anaplasma marginale. Sera from 243 goats and 68 sheep from Ibimirim municipality were analyzed and frequencies of antibodies of 11.93% (29/243 and 16.17% (11/68 were found for goats and sheep, respectively. The epidemiological relevance of the findings was discussed.

  12. Evaluation of the adaptability of dairy goats in the Brazilian semiarid region with the aid of infrared thermography

    Directory of Open Access Journals (Sweden)

    Elisângela Maria Nunes da Silva

    2014-07-01

    Full Text Available The objective of this study was to evaluate the adaptability of dairy goats with aid of infrared thermography in the environmental conditions of the Brazilian semiarid region. Were used 36 female goats, with a mean of 2.5 years and an average weight of 45 kg, distributed in a completely randomized design 2 x 2 in a factorial arrangement; two genotypes (Anglo Nubian and Alpine Brown and two shifts (morning and afternoon, with 18 repetitions. Analysis of variance showed that the shift had significant effect (P<0.05 on rectal temperature (RT, average surface temperature (AST and thermal gradients, but the breed had no significant effect (P>0.05 and there was no significant interaction between breed and shift. With respect to physiological parameters: respiratory rate (RR and surface temperature of the muzzle of cinnamon there was significant effect of breed and shift and significant interaction between breed and shift (P<0.05. Positive correlations between physiological parameters and room temperature and negative correlation between thermal gradients and more parameters. The Anglo Nubian breed had become more adapted to the semi-arid environmental conditions representing a good alternative for breeding programs. The Alpine breed increased respiratory effort required to dissipate heat and maintain homeothermy, proving to be more demanding regarding system creation and management in the semi-arid climatic conditions.

  13. Economic valuation of sheep genetic resources: implications for sustainable utilization in the Kenyan semi-arid tropics.

    Science.gov (United States)

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

    2008-12-01

    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.

  14. Hydrological modeling of the semi-arid Andarax river basin in southern Spain

    DEFF Research Database (Denmark)

    Andersen, Flemming Hauge; Jensen, Karsten Høgh; Sandholt, Inge

      The 2,265 km2 Andarax river basin located in Southern Spain is one of the most arid regions in Europe with a mean annual precipitation of 250-350 mm, which mainly falls (70%) in autumn and winter. The terrain changes from sea level at the coast to more than 2,500 m in the Sierra Nevada Mountains....... Most of the precipitation falling in the mountainous areas, where the unit Triassic schists dominates, is converted into overland flow, which runs directly to the rivers. In areas with limestone most of the precipitation infiltrates and is subsequently routed through fractures before discharging...... availability in the delta region. Due to the high evapotranspiration in semi-arid or arid regions groundwater recharge can be as low as 1 % of the precipitation. Thus it is essential to accurately predict the seasonal and regional distribution of actual evapotranspiration (ET) within the river catchment...

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

    Directory of Open Access Journals (Sweden)

    T. T. Jin

    2011-08-01

    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

  16. Seasonal dynamics of soil CO2 efflux in biodiverse semi-arid ecosystems of Western Australia

    Science.gov (United States)

    Muñoz-Rojas, Miriam; Lewandrowski, Wolfgang; Martini, Dylan; Erickson, Todd; Merritt, David; Dixon, Kingsley

    2015-04-01

    Introduction In recent years, soil respiration (Rs) has been a major research focus given the increase in atmospheric CO2 emissions and the large contribution of CO2 fluxes from soils. Rs is the second largest carbon flux in terrestrial ecosystems and globally accounts for 98±12 CO2-C yr-1 or ten times that produced by fossil fuel combustion. In addition to its importance in the global carbon cycle, Rs is a key indicator of ecosystem state and functioning. Despite the global importance of this process, there is still limited knowledge of its and responses to abiotic and biotic processes, particularly in arid and semi-arid areas. In this research we investigated the seasonal variations and controlling factors of Rs for different vegetation types in biodiverse ecosystems of the Pilbara region (Western Australia). This region, with a semi-arid climate and two main seasons (wet-summer and dry-winter), is an ancient landscape with diverse geology and high levels of regional endemism. Methods This research was conducted in seven study sites across the Pilbara region with similar native soils and analogous ecosystems representative of the area. A permanent plot was defined at each site which included three of the most representative and dominant vegetation cover types of the Pilbara ecosystems: trees (Corymbia spp.), shrubs (Acacia spp.), grasses (Triodia spp.), and bare soil. Soil sampling and field measurements were carried out in February 2014 (wet-summer season) and July 2014 (dry-winter season). Rs was measured with a portable soil CO2 flux chamber attached to a Li-Cor 6400 and, simultaneously, both temperature and soil moisture were determined. Results Soil CO2 efflux ranged from 0.57 µmol m-2 s-1 to 1.96 µmol m-2 s-1 in the dry-winter season and from 1.57 µmol m-2 s-1 to 3.91 µmol m-2 s-1 in the wet-summer season. Higher Rs rates were found in the wet-summer season in all vegetation types and below Corymbia spp. in both periods. Rs differed significantly

  17. Stem Biomass Production of Paulownia elongata × P. fortunei under Low Irrigation in a Semi-Arid Environment

    Directory of Open Access Journals (Sweden)

    Francisco Antonio García-Morote

    2014-10-01

    Full Text Available In semi-arid regions, afforestation with fast-growing species cultured with low irrigation can be an effective approach for environmental protection. An experiment was conducted to evaluate the stem biomass production of Paulownia in a semi-arid climate and clay soils under contrasting low-irrigation and fertilization treatments. The stem biomass at the stand level was estimated by applying allometric equations fitted in sample resprouts and inventory data. The results show that biomass production improved when either irrigation or fertilizer was added, but the combination of a higher dose of irrigation and fertilization did not lead to the highest biomass production; thus water availability was the main factor controlling biomass production. Under the higher dose of irrigation, the absence of a fertilizer effect would be due in part to the fertile soil, which could supply sufficient nutrients for Paulownia growth at the higher level of soil moisture. The stem biomass estimated ranged from 2.14 to 4.50 t×ha−1 (lower irrigation dose without fertilization, and higher irrigation with fertilization. The greater production was similar to other studies in the Mediterranean area receiving more irrigation. Thus, this study permitted us to understand the potential of Paulownia to provide biomass in semi-arid environments with low irrigation due to water use restrictions.

  18. Valuing goat genetic resources: a pro-poor growth strategy in the Kenyan semi-arid tropics.

    Science.gov (United States)

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

    2008-12-01

    Goats, "the poor man's cow", provide very important genetic resources that can be exploited for continued improvements of the livelihoods of poor livestock keepers in the semi-arid tropics. This study presents the evaluation of the economic values of goat genetic resources (GGRs) in terms of the important non-market traits embedded in goats and how this information can be utilised to improve livelihoods in semi-arid regions. The results obtained from mixed logit models derived from stated choice data collected from 314 respondents in the semi-arid Marsabit district of Kenya reveal that disease resistance is the most highly valued trait whose resultant augmentation results into a welfare improvement of up to KShs.2899. Drought tolerance and milk traits were found to be implicitly valued at KShs.2620 and 1179 respectively. The study further revealed that improvement in milk trait in does, body size and disease resistance traits in bucks, and drought tolerance trait in both does and bucks will collectively improve the producers' welfare hence should be given priority. However, improvement in the reproduction and production ("overall body condition/ meatiness" trait) potential of goats will be worthwhile only if issues concerning access to pasture and water resources are addressed prior and simultaneously.

  19. Resource flows, crops and soil fertility management in smallholder farming systems in semi-arid Zimbabwe

    NARCIS (Netherlands)

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

    2009-01-01

    Poor soil fertility and erratic rains are major constraints to crop production in semi-arid environments. In the smallholder farming systems of sub-Saharan Africa, these constraints are manifested in frequent crop failures and endemic food insecurity. We characterized a semi-arid smallholder farming

  20. Soil biogenic emissions of nitric oxide from a semi-arid savanna in South Africa

    Science.gov (United States)

    Feig, G. T.; Mamtimin, B.; Meixner, F. X.

    2008-12-01

    Soils of arid and semi-arid ecosystems are important biogenic sources of atmospheric nitric oxide (NO), however, there is still a shortage of measurements from these systems. Here we present the results of a laboratory study of the biogenic emission of NO from four different landscape positions of the Kruger National Park (KNP), a large conservation area in a semi-arid region of South Africa. Results show that the highest net potential NO fluxes come from the low lying (footslope) landscape regions, which have the largest nitrogen stocks and highest rates of nitrogen input into the soil. Net potential NO fluxes from midslope and crest regions were considerably lower. The maximum release of NO occurred at fairly low soil moisture contents of 10%-20% water filled pore space. Using soil moisture and temperature data obtained in situ at the Kruger National Park flux tower site, net potential NO fluxes obtained in the laboratory were converted to field fluxes for each of the four landscape positions for the period 2003 to 2005. The highest field NO flux is from footslope positions, during each of these years and emissions ranged from 1.5-8.5 kg ha a (in terms of mass of nitrogen). Remote sensing and Geographic Information Systems techniques were used to up-scale field NO fluxes on a regional basis indicating that the highest emissions occurred from the midslope positions, due to their large geographical extent in the considered research area. Emissions for the KNP Skukuza land type (56 000 ha) ranged from 20×103 kg in 2004 to 34×103 kg in 2003. The importance of landscape characteristics in the determination of regional biogenic NO soil emission is emphasized.

  1. 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.

    2011-01-01

    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 s

  2. The use of soil quality indicators to assess soil functionality in restored semi-arid ecosystems

    Science.gov (United States)

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

    2016-04-01

    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

  3. Tracer-based studies of soil water movement in semi-arid forests of New Mexico

    Science.gov (United States)

    Newman, Brent D.; Campbell, Andrew R.; Wilcox, Bradford P.

    1997-09-01

    The related issues of water movement and contaminant transport in arid and semi-arid environments have generated considerable interest and concern in the last few decades. Essential to understanding these issues is knowledge of how water moves through the soils that form the uppermost part of the vadose zone. The use of tracers, both natural and artificially introduced, is proving to be an effective method for gaining such knowledge in dry regions, where investigation by other means is difficult. In this study, natural stable-isotope and chloride tracers were used to investigate water movement in the soils of a piñon-juniper woodland and of a ponderosa pine forest on the Pajarito Plateau in northern New Mexico. The objectives were to (1) estimate and compare near-surface flux rates and evaluate the importance of evaporation in the two communities, and (2) determine to what extent differences in flux rates and evaporation are due to differences in plant cover and/or soil hydraulic properties. The results of this study will aid in evaluating the potential for contaminant mobility in semi-arid systems such as the Pajarito Plateau and, in addition, will increase understanding of nutrient distributions and plant water use in semi-arid environments. The stable-isotope data indicate a similarity between the piñon-juniper and ponderosa communities with respect to evaporation: in both, it is restricted mainly to the upper 10 cm of soil. Chloride profiles from the two communities, on the other hand, show a distinct difference with respect to downward fluxes: in the ponderosa pine forest, these fluxes (≈0.02 cm year -1) are an order of magnitude lower than those in the piñon-juniper woodland (≈0.2 cm year -1), even though total precipitation is about 4 cm year -1 higher in the ponderosa pine forest. This difference, however, appears to be related not to plant cover, but to differences in soil hydraulic properties. The soils of the ponderosa pine forest contain clay

  4. Observing and Quantifying Ecological Disturbance Impacts on Semi-arid Biomes in the Southwestern US.

    Science.gov (United States)

    Litvak, M. E.; Krofcheck, D. J.; Morillas, L.; Fox, A. M.

    2014-12-01

    The magnitude of carbon fluxes through arid and semi-arid ecosystems is considered modest, but integrated over the ~40% of the global land surface covered by these ecosystems, the total carbon stored is almost twice that in temperate forest ecosystems. In the semi-arid Southwestern U.S., drought and rising temperatures have triggered insect outbreaks, fire and widespread mortality in the past 5 years, all of which are predicted to increase in the next century. Understanding how resilient carbon pools and fluxes in these biomes are to these disturbances constitutes a large uncertainty in our ability to understand both carbon and energy flux dynamics in this region. We use an 8 year record (2007-2014) of continuous measurements of net ecosystem exchange of carbon (NEE) and its components (gross primary productivity (GPP) and ecosystem respiration (Re), and evapotranspiration (ET) made over the New Mexico Elevation Gradient (NMEG) network of flux tower sites (desert grassland, creosote shrubland, juniper savanna, piñon-juniper woodland, ponderosa pine and subalpine mixed conifer) to quantify the biome-specific responses of carbon and water dynamics to these disturbances. In particular, we focus on biome-specific responses across the NMEG biomes to the extended drought in this region from 2011-2014, and to the widespread mortality observed in piñon-juniper woodlands following the turn of the century drought (1999-2002) and multi-year recent drought. Finally, we compare functional responses of land-surface fluxes to recent catastrophic fires (grassland, subalpine conifer biomes), and insect outbreaks (subalpine conifer and piñon-juniper woodland biomes). We discuss the results in terms of which disturbances have contributed to and are likely to trigger the largest changes in carbon sequestration in this region in response to predicted climate change scenarios.

  5. Effects of stubble and mulching on soil erosion by wind in semi-arid China

    Science.gov (United States)

    Cong, Peifei; Yin, Guanghua; Gu, Jian

    2016-07-01

    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 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.

  6. Reproduction in the one humped camel (Camelus dromedarius in semi arid Nigeria

    Directory of Open Access Journals (Sweden)

    M.A. Umaru

    2013-02-01

    Full Text Available This review examines the one humped camel (Camelus dromedarius a considerable number of the dromedary about 50,000 is found in the semi-arid part of Northern Nigeria. Apart from the wide use of the camel as a draught animal the camel now serve as a source of milk, meat and hide in this region, these notes examines the anatomical basis of reproduction, pregnancy, and its diagnosis, fertility, and the application of modern  techniques in camel reproduction. Different techniques and equipments are now being employed for explicit study of the reproductive processes in the camel. Transrectal ultrasaonographic scanning machine is now being used to study ovulation pattern and timing, video endoscopic hysteroscopy is another technique employed to study various aspects of the camel conceptus. Techniques like oestrous synchronization, super ovulation, semen collection artificial insemination, embryo recovery and transfer are all used in the study of camel.

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

    DEFF Research Database (Denmark)

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

    2006-01-01

    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...

  8. 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

    2005-08-01

    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

  9. 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

    2011-01-01

    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

  10. Variability of atmospheric carbonyl sulfide at a semi-arid urban site in western India.

    Science.gov (United States)

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

    2016-05-01

    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.

  11. Pathologic evaluation of testis and epididymis of hairy rams in the semi-arid region of Piaui State Avaliação patológica de testículos e epidídimos de ovinos deslanados da região semi-árida do Estado do Piauí

    Directory of Open Access Journals (Sweden)

    F.L.A. Costa

    2007-10-01

    Full Text Available The gross and histological examinations of testis and epididymis of 53 crossbred hairy rams in the semi-arid region of Piaui State showed 34 (64.1% animals with pathologic changes: one animal presented (1.9% testicle hipoplasia; 35 (66% degenerative changes, being 13 (24.5% related to testicular degeneration, three (5.7% to intraepithelial cysts in the epididymal epithelia and 19 (35.8% to retention cysts in the epididymis; 11 (20.7% inflammatory alterations, being five (9.4% related to epididymitis, four (7.5% to orchitis and two (3.8% to spermatic granulomas. The animals with hypoplasic testicle, testicular degeneration and inflammatory alterations were classified as sub-fertile.Os exames macroscópico e microscópico de testículos e epidídimos de 53 ovinos deslanados da região semi-árida do estado do Piauí revelaram34 (64,1% animais acometidos por processos patológicos, assim distribuídos: um animal (1,9% apresentou hipoplasia testicular, 35 (66,0% mostraram alterações degenerativas, sendo 13 (24,5% casos de degeneração testicular, três (5,7% de cisto intraepitelial no epidídimo e 19 (35,8% de cisto de retenção congênita no epidídimo; 11 (20,7% de alterações inflamatórias, sendo cinco (9,4% de epididimite, quatro (7,5% de orquite e dois (3,8% de granuloma espermático. Os animais com hipoplasia testicular, degeneração testicular e alterações inflamatórias foram classificados como subférteis.

  12. 基于高密度电阻率成像法的陇中半干旱区土壤含水量监测研究%A soil water content monitoring in Longzhong semi-arid region by high-density electrical resistivity tomography

    Institute of Scientific and Technical Information of China (English)

    岳宁; 董军; 李玲; 阚飞; 王刚; 黄少文; 魏国孝

    2016-01-01

    土壤含水量是影响半干旱区农作物生长的重要因素。为了准确测定土壤含水量的变化动态以指导农业高效用水,近年来,利用地球物理测量方法研究高分辨率的水流入渗,已经越来越受到欢迎和重视。本文以陇中半干旱区玉米田为例,通过在土壤表面布置电极,利用高密度电阻率成像法(ERT)对降雨前后土壤二维剖面进行电阻率数据测量,实现对土壤二维剖面电阻率值和含水量监测,解释不同条件下土壤含水量变化的原因,建立陇中半干旱区农田土壤电阻率和含水量之间的相关关系。结果表明:降水入渗使得二维剖面土壤电阻率整体呈明显降低趋势,反演得到的电阻率图像局部电阻值“高-低-高”的变化过程,与一次降水过程前后“干-湿-干”的循环过程一致。土壤含水量实测值与估计值之间有较为显著的线性关系(R2=0.6518, n=96)。在0~2.0 m深度范围内,总体估计偏差较小,为0.74%;土壤含水率的估计精度较高,为2.64%。0~0.5 m 土层(H1)含水量监测探头分布密集,数据采集较为准确,故 H1层估计精度略高于0.5~2.0 m 层(H2)。相比之前利用实测工具进行野外测量, ERT 测量方法精度较高。本文提供了一个高分辨率的土壤结构二维分布与水分运移过程的图像,同时为实现精确和高效的农业用水管理提供一种新途径。%Soil water content (SWC) is a key factor influencing crop growth in semi-arid regions. Monitoring the variations in SWC is critical for agriculture. In recent years, geophysical survey has been used in the study of high-resolution detection of water infiltration and it is hugely popular because of its zero-damage to soil micro-structure and easy measurement. With a maize field in Longzhong semi-arid region as the case study, we used high-density electrical resistivity tomography (ERT) to measure (before and after the precipitation) two

  13. 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

    2006-12-01

    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

  14. Modeling mechanisms of vegetation change due to fire in a semi-arid ecosystem

    Science.gov (United States)

    White, J.D.; Gutzwiller, K.J.; Barrow, W.C.; Randall, L.J.; Swint, P.

    2008-01-01

    Vegetation growth and community composition in semi-arid environments is determined by water availability and carbon assimilation mechanisms specific to different plant types. Disturbance also impacts vegetation productivity and composition dependent on area affected, intensity, and frequency factors. In this study, a new spatially explicit ecosystem model is presented for the purpose of simulating vegetation cover type changes associated with fire disturbance in the northern Chihuahuan Desert region. The model is called the Landscape and Fire Simulator (LAFS) and represents physiological activity of six functional plant types incorporating site climate, fire, and seed dispersal routines for individual grid cells. We applied this model for Big Bend National Park, Texas, by assessing the impact of wildfire on the trajectory of vegetation communities over time. The model was initialized and calibrated based on landcover maps derived from Landsat-5 Thematic Mapper data acquired in 1986 and 1999 coupled with plant biomass measurements collected in the field during 2000. Initial vegetation cover change analysis from satellite data showed shrub encroachment during this time period that was captured in the simulated results. A synthetic 50-year climate record was derived from historical meteorological data to assess system response based on initial landcover conditions. This simulation showed that shrublands increased to the detriment of grass and yucca-ocotillo vegetation cover types indicating an ecosystem-level trajectory for shrub encroachment. Our analysis of simulated fires also showed that fires significantly reduced site biomass components including leaf area, stem, and seed biomass in this semi-arid ecosystem. In contrast to other landscape simulation models, this new model incorporates detailed physiological responses of functional plant types that will allow us to simulated the impact of increased atmospheric CO2 occurring with climate change coupled with fire

  15. Mortalidade perinatal de cordeiros no semi-árido da Paraíba Perinatal mortality of lambs in the semi-arid region of Paraíba, Brazil

    Directory of Open Access Journals (Sweden)

    Janduí Escarião da Nóbrega Jr

    2005-09-01

    Full Text Available As causas de mortalidade perinatal em ovinos foram estudadas de março de 2002 a outubro 2004 em 27 fazendas da região semi-árida da Paraíba. De 90 cordeiros necropsiados, 41,1% morreram de infecções neonatais, 23,3% por malformações, 10% por inanição/hipotermia, 10% por distocia, 2,2% por predação e 4,4% foram abortos sem causa identificada. Em relação ao momento da morte, 4,4% dos cordeiros morreram antes do parto, 10% durante o parto, 30% no primeiro dia de vida, 20% entre o 2º e 5º dia e 35,6% entre o 4º e 28º dia após o parto. A assistência das ovelhas durante o parto, a desinfecção do umbigo dos cordeiros, a ingestão de colostro 2 a 6 horas após o parto, e a manutenção das ovelhas em locais adequados durante e após o parto contribuiriam para diminuir as mortes perinatais por distocia e infecções neonatais. A alta freqüência de malformações, em diferentes raças, sugere que esses defeitos sejam causados por uma planta tóxica. Os principais defeitos observados foram a flexão permanente dos membros anteriores, braquignatismo, fenda palatina e outras alterações dos ossos da cabeça. Recentemente foi demonstrado o efeito teratogênico de Mimosa tenuiflora ("jurema-preta", uma planta muito comum na região semi-árida, nas áreas de caatinga, que aparentemente é responsável pelas malformações. Os cordeiros mortos por inanição/hipotermia tiveram baixo peso ao nascimento (1,37 ± 0,7kg o que sugere que a principal causa dessas mortes é a deficiente nutrição da mãe durante o último terço da gestação. Considerando-se que na região nordeste, na maioria das fazendas, os carneiros permanecem com as ovelhas durante todo o ano, a adoção de uma estação de monta definida contribuiria para a diminuição da mortalidade perinatal.The causes of perinatal lamb mortality were studied, from March 2002 to October 2004, on 27 farms in the semiarid region of Paraíba, northeastern Brazil. In 90 lambs necropsied

  16. 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

    2010-01-01

    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

  17. Ethno-ornithology and conservation of wild birds in the semi-arid Caatinga of northeastern Brazil.

    Science.gov (United States)

    Alves, Rômulo Romeu Nóbrega; Leite, Railson Cidennys Lourenço; Souto, Wedson Medeiros Silva; Bezerra, Dandara M M; Loures-Ribeiro, Alan

    2013-02-27

    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, human pressure on the avifauna

  18. Water resource monitoring in semi-arid environment through the synergic use of SAR data and hydrological models

    Science.gov (United States)

    Amitrano, Donato; Di Martino, Gerardo; Iodice, Antonio; Mitidieri, Francesco; Papa, Maria Nicolina; Riccio, Daniele; Ruello, Giuseppe

    2016-10-01

    In semi-arid regions, small reservoirs are widely employed for facing seasonal in water availability due to the alternation of a short rainy season and of a very long dry season. Therefore, their monitoring is fundamental for local rural communities wellness. In this paper, we present a novel framework for water resources management exploiting the synergy of synthetic aperture radar (SAR) data and hydrological models. The pilot project was implemented in Burkina Faso, showing good potentialities for cheap and continuous monitoring of the environment through the exploitation of a multi-disciplinary framework.

  19. 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

    2012-03-01

    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

  20. Avaliação de um modelo físico de produção de bovinos no semi-árido integrando caatinga, capim-buffel e leucena.: I. fase de cria A physical model evaluation of a caatinga/buffel grass/leucaena integrated system for cattle production in the semi-arid region.: I. cow-calf operation

    Directory of Open Access Journals (Sweden)

    Clovis Guimarães Filho

    1999-09-01

    Full Text Available O estudo teve como objetivo avaliar um modelo físico do sistema de cria de bovinos para as áreas mais secas do Semi-Árido brasileiro, associando a pastagem natural com pastos cultivados tolerantes à seca. A caatinga foi pastejada no período verde, e o capim buffel no restante do ano. A suplementação com leucena ocorreu no período seco, sob pastejo direto e feno no cocho. Parâmetros de desempenho, monitorados de novembro de 1991 a outubro de 1995, mostraram uma taxa média de parição da ordem de 72,8% ao ano e taxas de mortalidade praticamente nulas. O peso vivo médio dos bezerros aos 205 dias de idade foi de 153,4 kg e a produ- ção de bezerros desmamados foi de 109,5 kg/matriz exposta/ano e de 25,5 kg/hectare/ano. Os resultados são considerados bastante expressivos, considerando-se que mais da metade da área era ocupada com pastagens nativas de caatinga e que a oferta de leucena foi limitada pela ocorrência de uma forte estiagem.The study was designed to evaluate a physical model performance of a cow-calf operation system for the semi-arid region, in Brazil. Native pastures (caatinga were grazed during the rainy season and buffel grass pastures over the rest of the year. Leucaena supplementation, under rotational grazing and as hay, was provided during the dry season. Performance parameters, monitored from November 1991 to October 1995, showed a 72.8% annual calving rate and a very low mortality rate. Weaning weights of calves averaged 153.4 kg at 205 days. Production of calf weaned was 109.5 kg/cow run/year and 25.5 kg/ha/year. Performance data can be concluded to be very promising if considered that above half the total area was covered by native pastures and that leucaena hay supplementation was strongly limited by occurrence of a severe drought period.

  1. SUPLEMENTAÇÃO ALIMENTAR DE CABRAS ANGLO-NUBIANAS NA ÉPOCA CHUVOSA, NA REGIÃO SEMI-ÁRIDA DO NORDESTE BRASILEIRO FOOD SUPPLEMENTATION OF ANGLO-NUBIAN GOATS IN RAINY SEASON IN SEMI-ARID REGION OF NORTHEAST BRAZIL

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    NELSON NOGUEIRA BARROS

    1999-11-01

    Full Text Available Foi realizado um experimento para avaliar a influência da suplementação alimentar na produção de leite de cabras da raça Anglo-nubiana, durante a época chuvosa, na região semi-árida do Nordeste brasileiro. Vinte e quatro cabras foram mantidas em pastagem nativa rebaixada, distribuídas ao acaso, por tipo de parto e produção de leite, em três níveis de suplementação: N0 - sem suplementação, N1 -150 g de concentrado/animal/dia e N2 - 300 g de concentrado/animal/dia. Não houve diferença significativa (p>0,05 entre os níveis de suplementação. A produção de leite foi descrita por uma regressão múltipla em função do período de lactação em semana. A interação semana x níveis de suplementação foi significativa (pThis experiment was carried out to evaluate the influence of food supplementation on milk production of Anglo-nubian goats, during the rainy season, in semi-arid region of Northeast Brazil. Twenty four goats were maintained in lowered "caatinga", distributed randomly according to the parturition order and milk production in three supplementation levels: N0 - no supplementation, N1 - 150 g of concentrate/animal/day and N2 - 300 g of concentrate/animal/day. There was no significant difference (p>0.05 between supplementation levels. Milk production was described by multiple regression to lactation period, in week. The results showed that the best option to produce milk with Anglo-nubian, during the wet season, is 300 g of concentrate/animal/day.

  2. A groundwater development program for semi-arid northeast Brazil

    Energy Technology Data Exchange (ETDEWEB)

    Maurice, Y. [Geological Survey of Canada, Ottawa, ON (Canada)

    2001-07-01

    A four-year technology transfer program, the Northeastern Brazil Groundwater Project, was initiated by the Geological Survey of Canada and the Geological Survey of Brazil (CPRM), in collaboration with several public and private institutions in both countries and was approved in April 2000. The program also benefits from support from the Canadian International Development Agency. The objective of the program is to develop the groundwater resources of northeast Brazil to provide the long-term stability socio-economic of the region. The area covers approximately one million square kilometres, touches three states and is frequently affected by droughts. The population hovers around the 25 million mark. The groundwater is brackish and contained in open bedrock fractures in the Precambrian basement and shallow alluvial aquifers. The difficulty associated with the predictability of the distribution forced many communities to store rain water in small reservoirs, increasing the risk of contamination and causing evaporation problems. A groundwater resource assessment program of the entire area was launched by CPRM in early 2000, which involved geological mapping, inventorying water wells, and measuring standard well and groundwater parameters, documenting water usage and supply and quality problems. The harder hit regions are the sites of more technologically advanced activities combined with considerable social work performed by Canadians and Brazilians alike. Seminars, short courses, in-field demonstrations of techniques and equipment, joint pilot-scale projects, technical visits and the training of Brazilians in Canada are the methods of choice for the transfer of technology and know-how by Canadians. Ground and airborne geophysics,remote sensing, hydrofrac, artificial aquifer recharge, groundwater modeling and geographic information system techniques are the technologies to be introduced. Great expectations are placed on the use of airborne electromagnetics (EM) for the

  3. Semi-Arid Water Resource Challenges - Can Water Harvesting Close the Gap?

    Science.gov (United States)

    Meixner, T.; Niraula, R.; Norman, L.; Pivo, G.; Gerlak, A.; Pavao-Zuckerman, M.; Henry, A.

    2015-12-01

    Water resource availability restricts development in arid and semi-arid regions of world. Past observations show that urban areas can increase stream discharge at least on a local scale. These results suggest that urbanization may increase the availability of wet water capable of being used by urban society. Here we present a combination of observational work demonstrating the increase of available water in urban areas of southern Arizona; and a modelling study demonstrating that future land use change may significantly increase river discharge across the Santa Cruz watershed which is ~12% urban. The observational data comes from over 30 watersheds varying in cover from undeveloped to highly urban and in spatial scale from a few square meters to thousands of square kilometers. The modelling study includes a conservation (~35% urban), megalopolitan (~34% urban) and business as usual scenario (~38% urban) for land use change due to regional population growth. All land use change scenarios result in significant increases in watershed streamflow. Depending upon pattern of urbanization, streamflow increased as much 88% in some watershed locations; demonstrating the potential to partially meet water resources demands in the region with water produced by the urbanization process. This water could be used regionally or locally, and significant efforts at implementing water harvesting in the region have been pursued. However, the ability to scale such implementation and overcome the physical, and social barriers to implementation are currently unquantified.

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

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    J. M. Grünzweig

    2007-07-01

    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. The total amount of C produced by the forest was estimated as 6250 g C m−2. 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. Our results showed the considerable potential for C sequestration, particularly in soils, following afforestation in semi-arid regions, which is particularly relevant in light of persistent

  5. 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

    2009-04-01

    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.

  6. 六盘山半干旱区华北落叶松林的生长季蒸散量和组分特征%The evapotranspiration and its partition in growing season for a stand of Larix principis-rupprechtii plantation in the semi-arid region of Liupan Mountains, NW China

    Institute of Scientific and Technical Information of China (English)

    李振华; 王彦辉; 于澎涛; 童鸿强; 王艳兵; 刘千

    2013-01-01

    The canopy transpiration (T), canopy interception (I) and forest floor evapotranspiration (ETf) in a stand of Larix principis-rupprechtii plantation were continuously measured in the growing season (May-October) of 2009—2011, using the techniques including thermal diffusion probes and micro-lysimeters, in a semi-arid small watershed of Diediegou located at the Liupan Mountains of Ningxia Hui Autonomous Region, northwest China. Then, the total stand evapotranspiration (ET), the relative contribution of each ET component and their monthly variation were analyzed. The results showed that the total ET in the growing season of 2009, 2010 and 2011 was 446, 532, 426 mm, respectively;this inter-annual difference was influenced firstly by the water condition, then by the air temperature and stand LAI. Within the stand ET, the T amounted to 35%, while the I and ETf amounted to 18%and 47%, respectively. This meant that 53%of the total stand ET was caused by the stand canopy. The monthly T was mainly constrained by the vapor pressure difference (VPD) and solar radiation when soil water was abundant, but showing no significant relation with the meteorological factors under water deficit condition. The monthly ratio of T/ET decreased gradually in the growing season, from the maximum of 51% in May to the minimum of 22% in October. 70% of I concentrated in the rainy period (July-September), the variation of monthly I was closely dependent on the monthly precipitation. The monthly ratio of I/ET was lower in May and June with an average of 11%;and higher in the period from July to October with an average of 21%. The monthly ETf in the growing season varied in a pattern of single peak which appeared in August. This was mainly determined by the variation of monthly precipitation. However, the monthly ratio of ETf/ET presented an increasing tendency, from 32% in May to 57% in October. This stand with semi-arid climate studied in this paper is a typical water-limited ecosystem, and

  7. Using stable isotopes (δ^{18}O and δ$D) of gypsum hydration water to unravel the mode of gypsum speleothem formation in semi-arid caves

    Science.gov (United States)

    Gázquez, Fernando; Calaforra, Jose Maria; Evans, Nicholas P.; Hodell, David A.

    2016-04-01

    Subaerial gypsum speleothems form during the evaporation of calcium-sulfate-rich solutions in caves. The evaporation of infiltration water is the widely accepted mechanism to explain precipitation of gypsum speleothems; i.e., the dissolution of gypsum host-rock (e.g. Messinian marine gypsum) supplies Ca2+ and SO42- ions to cave waters and subsequent evaporation leads to gypsum saturation. However, water condensation actively occurs in caves of semi-arid regions and plays a key role in subaerial cave speleogenesis and recharge of aquifers in low-rainfall environments. To date, water condensation in karstic environments has not been considered as an important factor in gypsum speleothem formation. We collected speleothem samples from the upper passages of Covadura Cave in the gypsum karst of Sorbas (Almeria, SE Spain). This cave is located in a temperate (annual mean temperature of 19.5oC), semi-arid region (

  8. Effectiveness of conservation agriculture practices on soil erosion processes in semi-arid areas of Zimbabwe

    Science.gov (United States)

    Chikwari, Emmanuel; Mhaka, Luke; Gwandu, Tariro; Chipangura, Tafadzwa; Misi Manyanga, Amos; Sabastian Matsenyengwa, Nyasha; Rabesiranana, Naivo; Mabit, Lionel

    2016-04-01

    - The application of fallout radionuclides (FRNs) in soil erosion and redistribution studies has gained popularity since the late 1980s. In Zimbabwe, soil erosion research was mostly based on conventional methods which included the use of erosion plots for quantitative measurements and erosion models for predicting soil losses. Only limited investigation to explore the possibility of using Caesium-137 (Cs-137) has been reported in the early 1990s for undisturbed and cultivated lands in Zimbabwe. In this study, the Cs-137 technique was applied to assess the impact of soil conservation practices on soil losses and to develop strategies and support effective policies that help farmers in Zimbabwe for sustainable land management. The study was carried out at the Makoholi research station 30 km north of the Masvingo region which is located 260 km south of Harare. The area is semi-arid and the study site comprises coarse loamy sands, gleyic lixisols. The conservation agriculture (CA) practices used within the area since 1988 include (i) direct seeding (DS) with mulch, (ii) CA basins with mulch, and (iii) 18 years direct seeding, left fallow for seven years and turned into conventional tillage since 2012 (DS/F/C). The Cs-137 reference inventory was established at 214 ± 16 Bq/m2. The mean inventories for DS, CA basins and DS/F/C were 195, 190 and 214 Bq/m2 respectively. Using the conversion Mass Balance Model 2 on the Cs-137 data obtained along transects for each of the practices, gross erosion rates were found to be 7.5, 7.3 and 2.6 t/ha/yr for direct seeding, CA basins and the DS/F/C while the net erosion rates were found to be 3.8, 4.6 and 0 t/ha/yr respectively. Sediment delivery ratios were 50%, 63% and 2% in the respective order. These preliminary results showed the effectiveness of DS over CA basins in erosion control. The efficiency of fallowing in controlling excessive soil loss was significant in the plot that started as DS for 18 years but left fallow for 7

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

    Science.gov (United States)

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

    2014-09-01

    Mine wastes introduce anthropogenic weathering profiles to the critical zone that often remain unvegetated for decades after mining cessation. As such, they are vulnerable to wind and water dispersion of particulate matter to adjacent ecosystems and residential communities. In sulfide-rich ore tailings, propagation to depth of the oxidative weathering front controls the depth-variation in speciation of major and trace elements. Despite the prevalence of surficial mine waste deposits in arid regions of the globe, few prior studies have been conducted to resolve the near-surface profile of sulfide ore tailings weathered under semi-arid climate. We investigated relations between gossan oxidative reaction-front propagation and the molecular speciation of iron and sulfur in tailings subjected to weathering in a semi-arid climate at an EPA Superfund Site in 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 samples with

  10. Roots of forbs sense climate fluctuations in the semi-arid Loess Plateau: Herb-chronology based analysis

    Science.gov (United States)

    Shi, Songlin; Li, Zongshan; Wang, Hao; von Arx, Georg; Lü, Yihe; Wu, Xing; Wang, Xiaochun; Liu, Guohua; Fu, Bojie

    2016-06-01

    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.

  11. Mapping Ecological Processes and Ecosystem Services for Prioritizing Restoration Efforts in a Semi-arid Mediterranean River Basin

    Science.gov (United States)

    Trabucchi, Mattia; O'Farrell, Patrick J.; Notivol, Eduardo; Comín, Francisco A.

    2014-06-01

    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.

  12. Overlap in nitrogen sources and redistribution of nitrogen between trees and grasses in a semi-arid savanna.

    Science.gov (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

    2014-04-01

    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.

  13. Interaction of water components in the semi-arid Huasco and Limarí river basins, North Central Chile

    Directory of Open Access Journals (Sweden)

    G. Strauch

    2009-10-01

    Full Text Available 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.

  14. Mapping ecological processes and ecosystem services for prioritizing restoration efforts in a semi-arid Mediterranean river basin.

    Science.gov (United States)

    Trabucchi, Mattia; O'Farrell, Patrick J; Notivol, Eduardo; Comín, Francisco A

    2014-06-01

    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.

  15. Land degradation assessment by geo-spatially modeling different soil erodibility equations in a semi-arid catchment.

    Science.gov (United States)

    Saygın, Selen Deviren; Basaran, Mustafa; Ozcan, Ali Ugur; Dolarslan, Melda; Timur, Ozgur Burhan; Yilman, F Ebru; Erpul, Gunay

    2011-09-01

    Land degradation by soil erosion is one of the most serious problems and environmental issues in many ecosystems of arid and semi-arid regions. Especially, the disturbed areas have greater soil detachability and transportability capacity. Evaluation of land degradation in terms of soil erodibility, by using geostatistical modeling, is vital to protect and reclaim susceptible areas. Soil erodibility, described as the ability of soils to resist erosion, can be measured either directly under natural or simulated rainfall conditions, or indirectly estimated by empirical regression models. This study compares three empirical equations used to determine the soil erodibility factor of revised universal soil loss equation prediction technology based on their geospatial performances in the semi-arid catchment of the Saraykoy II Irrigation Dam located in Cankiri, Turkey. A total of 311 geo-referenced soil samples were collected with irregular intervals from the top soil layer (0-10 cm). Geostatistical analysis was performed with the point values of each equation to determine its spatial pattern. Results showed that equations that used soil organic matter in combination with the soil particle size better agreed with the variations in land use and topography of the catchment than the one using only the particle size distribution. It is recommended that the equations which dynamically integrate soil intrinsic properties with land use, topography, and its influences on the local microclimates, could be successfully used to geospatially determine sites highly susceptible to water erosion, and therefore, to select the agricultural and bio-engineering control measures needed.

  16. Diurnal and Seasonal Variation of Surface Urban Cool and Heat Islands in the Semi-Arid City of Erbil, Iraq

    Directory of Open Access Journals (Sweden)

    Azad Rasul

    2016-09-01

    Full Text Available The influence of land surface temperature (LST makes the near-surface layer of the troposphere a key driver of urban climate. This paper assesses the temporal formation of the daytime Surface Urban Cool Island (SUCI and night-time Surface Urban Heat Island (SUHI effect in Erbil, Iraq, situated in a semi-arid climate region. LST retrievals from the Moderate Resolution Imaging Spectroradiometer (MODIS Aqua and Terra and MODIS Normalized Difference Vegetation Index (NDVI from January 2003 to December 2014 are analysed. The relationships of LST with NDVI and the Normalized Multi-band Drought Index (NMDI are investigated in order to assess the influence of vegetation and moisture on the observed patterns of LST and the SUCI/SUHI. The results indicate that during the daytime, in summer, autumn and winter, densely built-up areas had lower LST acting as a SUCI compared to the non-urbanised area around the city. In contrast, at night-time, Erbil experienced higher LST and demonstrated a significant SUHI effect. The relationship between LST and NDVI is affected by seasonality and is strongly inverted during spring (r2 = 0.73; p < 0.01. Contrary to previous studies of semi-arid cities, a SUCI was detected, not only in the morning, but also during the afternoon.

  17. Validation of humidex in evaluating heat stress in the outdoor jobs in arid and semi-arid climates of Iran

    Directory of Open Access Journals (Sweden)

    Hamid Reza Heidari

    2016-09-01

    Full Text Available Introduction: Regarding development of several thermal indices and limitations of each, in this research applicability and validity of temperature- humidity index (Humidex were examined against the standard heat index, Wet Bulb Globe Temperature -WBGT, as well as tympanic temperature of subjects. Material and Method:  This cross-sectional study was done on 163 subjects at spring and summer (2013 in outdoor jobs of arid and semi-arid climates of Iran. Environmental parameters as well as tympanic temperature of subjects were measured simultaneously and then heat indices were determined. Data were analyzed using linear correlation charts and Kappa coefficient of agreement by means of SPSS software version 20. Results: A strong correlation was obtained between WBGT and Humidex in both arid and semi-arid regions (r>0.98, while the correlation between Humidex and tympanic temperature was moderate (r=0.5-0.8. Based on the obtained Kappa value, the agreement coefficient between Humidex and WBGT was 0.878. This value was obtained equal to 0.226 for the Humidex and tympanic temperature. Conclusion: The results of this study showed that Humidex can be applied as an appropriate substitute for the WBGT index. However, if evaluation of environmental condition with low air temperature or very hot situation is considered, relying only on the Humidex results will not provide a realistic estimation of thermal strain imposed to individuals.

  18. Fixation kinetics of chelated and non-chelated zinc in semi-arid alkaline soils: application to zinc management

    Science.gov (United States)

    Udeigwe, Theophilus K.; Eichmann, Madeleine; Menkiti, Matthew C.

    2016-07-01

    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.

  19. 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

    2014-11-01

    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.

  20. Coupled flow and salinity transport modelling in semi-arid environments: The Shashe River Valley, Botswana

    Science.gov (United States)

    Bauer, Peter; Held, Rudolf J.; Zimmermann, Stephanie; Linn, Flenner; Kinzelbach, Wolfgang

    2006-01-01

    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 and transpirative salt enrichment. An existing numerical code for coupled flow/transport simulations (SEAWAT) was adapted to this situation. Model results were checked against a large set of field data including water levels, water chemistry, isotope data and ground and airborne geophysical data. The resulting groundwater model was able to reproduce the long-term development of the freshwater lens located in Shashe River Valley as well as the decline in piezometric heads observed over the last decade. Furthermore, the old age of the saline water surrounding the central freshwater lens could be explained.

  1. Determination of uranium partition coefficients of a semi-arid soil in Bahia

    Energy Technology Data Exchange (ETDEWEB)

    Fernandes, Heloisa H.F.; Pontedeiro, Elizabeth M.; Su, Jian, E-mail: heloisa@lasme.coppe.ufrj.br, E-mail: bettinadulley@hotmail.com, E-mail: sujian@lasme.coppe.ufrj.br [Coordenacao dos Cursos de Pos-Graduacao em Engenharia (COPPE/UFRJ), Rio de Janeiro, RJ (Brazil). Lab. de Simulacao e Metodos de Engenharia; Dourado, Eneida R.G., E-mail: eneida@inb.gov.br [Industrias Nucleares do Brasil (INB), Rio de Janeiro, RJ (Brazil)

    2013-07-01

    In mining and processing industries, the subsurface is one of the most vulnerable compartments to environmental contamination. Understanding the interactions between soil and contaminants is critical for predicting the possible environmental impacts caused by mining and milling operations. One of the main parameters used for this purpose is the partition (or distribution) coefficient, K{sub d}, which allows a relatively simple modeling approach by grouping various sorption phenomena into a single value. However, this parameter is strongly influenced by the physical and chemical characteristics of the medium, such as soil type, pH and solution composition. Thus, this study aims to assess the values of K{sub d} for uranium of typical soils from Bahia's semi-arid region using two different types of solute, one being a standard solution of uranyl acetate and one the liquor of uranium generated during processing. To calculate this parameter, batch adsorption experiments were carried out and adsorption isotherms (linear, Langmuir and Freundlich) were constructed using the Mathematica software. Results obtained for a single type of soil showed reduced values of K{sub d} for a liquor containing uranium when compared to values obtained with the uranyl acetate solution. This indicates that uranium from liquor is less adsorbed onto soil particles, and hence may move more quickly into the subsurface. (author)

  2. Adaptation to drought in arid and semi-arid environments: Case of the Zambezi Valley, Zimbabwe

    Directory of Open Access Journals (Sweden)

    Emmanuel Mavhura

    2015-02-01

    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

  3. Effects of stubble and mulching on soil erosion by wind in semi-arid China.

    Science.gov (United States)

    Cong, Peifei; Yin, Guanghua; Gu, Jian

    2016-07-18

    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.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    1995-09-01

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

  5. Nestedness patterns of sand fly (Diptera: Psychodidae) species in a neotropical semi-arid environment.

    Science.gov (United States)

    Chaves, Luis Fernando; Añez, Nestor

    2016-01-01

    A common pattern in neotropical Leishmania spp. transmission is the co-occurrence of several sand fly (SF) species at endemic foci. We collected 13 SF spp. by direct aspiration in natural resting places (NRP) and 10 SF spp. with Shannon traps (ST), totaling 15 spp. with both methods, at 6 locations within a semi-arid region with endemic visceral leishmaniasis transmission in Falcón State, Northwestern Venezuela. We used null model testing of species co-occurrence and nestedness metrics estimated with our field data to ask whether SF species composition was segregated/aggregated, and if aggregated whether there was nestedness, i.e., whether species composition across sampling locations could be described by ordered subsets of species from the most species rich location in a landscape. Results showed that SF species were aggregated (Pspecies were present in species rich locations. Similarly, SF species were significantly nested (Pspecies nestedness might be partially shaped by dispersal limitation. Our data showed that three species of medical importance were common across the sampling locations: Lutzomyia gomezi, Lutzomyia panamensis and Lutzomyia evansi, suporting that vector species do not turnover in the studied setting.

  6. Great Basin semi-arid woodland dynamics during the late quaternary

    Energy Technology Data Exchange (ETDEWEB)

    Wigand, P.E.; Hemphill, M.L.; Sharpe, S.E. [Univ. and Community College System of Nevada, Reno, NV (United States)] [and others

    1995-09-01

    Semi-arid woodlands have dominated the middle elevations of Great Basin mountain ranges during the Holocene where subalpine woodlands prevailed during the Pleistocene. Ancient woodrat middens, and in a few cases pollen records indicate in the late Pleistocene and early Holocene woodland history lowered elevation of subalpine woodland species. After a middle Holocene retrenchment at elevations in excess of 500 meters above today, Juniper-dominated semi-arid woodland reached its late Holocene maximum areal extent during the Neoglacial (2 to 4 ka). These records, along with others indicate contracting semi-arid woodland after the Neoglacial about 1.9 ka. Desert shrub community expansion coupled with increased precariousness of wetland areas in the southern Great Basin between 1.9 and 1.5 ka coincide with shrinking wet-lands in the west-central and northern Great Basin. Coincident greater grass abundance in northern Great Basin sagebrush steppe, reaching its maximum between 1.5 and 1.2 ka, corresponds to dramatic increases in bison remains in the archaeological sites of the northern Intermontane West. Pollen and woodrat midden records indicate that this drought ended about 1.5 ka. Succeeding ameliorating conditions resulted in the sudden northward and downward expansion of pinon into areas that had been dominated by juniper during the Neoglacial. Maximum areal extent of pinon dominated semi-arid woodland in west-central Nevada was centered at 1.2 ka. This followed by 100 years the shift in dominance from juniper to pinon in southern Nevada semi-arid woodlands. Great Basin woodlands suffered from renewed severe droughts between .5 to .6 ka. Effectively wetter conditions during the {open_quotes}Little Ice Age{close_quotes} resulted in re-expansion of semi-arid woodland. Activities related to European settlement in the Great Basin have modified prehistoric factors or imposed new ones that are affecting woodland response to climate.

  7. 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

    Directory of Open Access Journals (Sweden)

    J. B. Andrade

    2004-04-01

    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

  8. 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

    Directory of Open Access Journals (Sweden)

    Patrícia B. Neves

    2010-05-01

    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

  9. 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

    Directory of Open Access Journals (Sweden)

    Fernando Bezerra Lopes

    2016-07-01

    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

  10. 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

    Directory of Open Access Journals (Sweden)

    IDERVAL FARIAS

    2000-02-01

    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

  11. 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: naper@ufpe.br

    2006-07-01

    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

  12. Land use change and carbon cycle in arid and semi-arid lands of East and Central Asia

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Dramatic changes in land use have occurred in arid and semi-arid landsof 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 inChina 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.

  13. Coupling stable isotope and satellite to inform a snow accumulation and melt model for data poor, semi-arid watersheds

    Science.gov (United States)

    Hublart, Paul; Sproles, Eric; Soulsby, Chris; Tetzlaff, Doerthe; Hevía, Andres

    2016-04-01

    At the most basic level watersheds catch, store, and release water. In semi-arid northern central Chile (29°-32°) snow and glacier melt dominate these basic hydrological stages. In this region precipitation is typically limited to three to five events per year that falls as snow in the High Cordillera at elevations above 3000 m a.s.l. The rugged topography and steep gradient makes snowfall rates highly variable in space and time. Despite its critical importance for water supply, high elevation meteorological data and measurements of snowpack are scarce due to limited winter access above 3000 m a.s.l. Due to the critically limited understanding of catch, store, and release processes most conceptual watershed models for this region remain speculative, are prone to over-parameterization, and greatly inhibits hydrological prediction in the region. Focused on two headwater watersheds of the Elqui River basin (1615-6040 m a.s.l., 429-566 km2) this study couples stable isotope and Moderate Resolution Imaging Spectrometer (MODIS) data to develop an improved conceptual model of how semi-arid mountain watersheds catch, store, and release water. MODIS snow-cover and land surface temperature data are used to inform an enhanced temperature-index Snow Accumulation and Melt (SAM) model. The use of remotely-sensed temperature data as input to this model is evaluated by comparison with an interpolated dataset derived from a few available meteorological stations. The outputs from the SAM model are used as inputs to a conceptual catchment model including two water stores (one standing for surface/subsurface processes and the other for deeper groundwater storage). The model is calibrated and evaluated from a Bayesian perspective using discharge data measured at the catchment outlets over a 15-year period (2000-2015). Stable isotope data collected during 2015-2016 is applied to better constrain model outputs. The combination of MODIS-based and isotope-based information proves very

  14. Economic analysis of a simulated alley cropping system for semi-arid conditions, using micro computers

    Energy Technology Data Exchange (ETDEWEB)

    Hoekstra, D.A.

    1983-01-01

    Returns were simulated for the semi-arid areas in Mackakos District, Kenya (bimodal rainfall distribution, 600 mm/yr) comparing the present system (maize and beans intercropped twice a year) with a Leucaena leucocephala hedgerow system. Although some of the assumptions contain a large element of uncertainty, the results were promising enough for the system to be considered further. 4 references.

  15. Determining soil erosion rates on semi-arid watersheds using radioisotope-derived sedimentation chronology 2327

    Science.gov (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...

  16. Conservation tillage systems and water productivity implications for smallholder farmers in semi-arid Ethiopia

    NARCIS (Netherlands)

    Temesgen, M.L.

    2007-01-01

    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

  17. Extensive Green Roof Species and Soilless Media Evaluations in Semi-arid Colorado

    Science.gov (United States)

    In the high elevation, semi-arid climate of Colorado, green roofs have not been scientifically tested. This research examined alternative plant species, soilless media blends and plant interactions on an existing, modular-extensive (shallow, 10 cm deep) green roof in Denver, Colo...

  18. Acclimation of Pistacia integerrima trees to frost in semi-arid environments depends on autumn's drought.

    Science.gov (United States)

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

    2017-03-01

    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 <=-1 MPa) had more soluble sugars and proline than the well-watered trees (-0.2 MPa). The dehydrated trees also froze at lower temperatures and were less damaged by freezing. Interestingly, we observed a significant increase in stem CO2 efflux at near-freezing temperatures that could be linked to frost protection. This novel finding challenges current paradigm of plant respiration-kinetics which predicts, according to Arrhenius equation, lower respiration rates during frost. Our results support the notion that drought and frost are analogous stresses that can independently activate corresponding physiological processes in trees and amplify protection. This inevitable stress response 'collaboration' may be the key to understanding how non-dormant perennial plants survive the highly variable weather patterns of early winters in semi-arid environments.

  19. Understanding hydrological variability for improved water management in the Semi-Arid Karkheh basin, Iran

    NARCIS (Netherlands)

    Masih, I.

    2011-01-01

    This study provides a hydrology based assessment of (surface) water resources and its continuum of variability and change at different spatio-temporal scales in the semi-arid Karkheh Basin, Iran, where water is scarce, competition among users is high and massive water resources development is under

  20. The challenges of rehabilitating denuded patches of a semi-arid environment in Kenya

    NARCIS (Netherlands)

    Mganga, K.Z.; Nyangito, M.M.; Musimba, N.K.R.; Nyariki, D.M.; Mwangombe, A.W.; Ekaya, W.N.; Muiri, W.M.; Clavel, D.; Francis, J.; Kaufmann, Von R.; Verhagen, J.

    2010-01-01

    Land degradation is a major problem in the semi-arid environments of Sub-Saharan Africa. Fighting land degradation is essential to ensure the sustainable and long-term productivity of the habited semiarid lands. In Kenya, grass reseeding technology has been used to combat land degradation. However,

  1. Energetics of the green iguana (Iguana iguana) in a semi-arid environment

    NARCIS (Netherlands)

    van Marken Lichtenbelt, Wouter David

    1991-01-01

    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 N

  2. Tillage and farmyard manure efects on crusting and compacting soils at Katumani, Semi-arid Kenya

    NARCIS (Netherlands)

    Biamah, E.K.; Sterk, G.; Stroosnijder, L.

    2008-01-01

    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

  3. Infiltration and planting pits for improved water management and maize yield in semi-arid Zimbabwe

    NARCIS (Netherlands)

    Nyakudya, I.W.; Stroosnijder, L.; Nyagumbo, I.

    2014-01-01

    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, scient

  4. Comparison of groundwater recharge estimation methods for the semi-arid Nyamandhlovu area, Zimbabwe

    NARCIS (Netherlands)

    Sibanda, T.; Nonner, J.C.; Uhlenbrook, S.

    2009-01-01

    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 r

  5. Soil quality improvement for crop production in semi-arid West Africa

    NARCIS (Netherlands)

    Ouédraogo, E.

    2004-01-01

    Soil quality maintenance and crop production improvement in semi-arid West Africa require appropriate cropping technologies, which are ecologically sound and economically viable. Thus, on-farm and on-station experiments have been carried out on the central plateau and in the south of Burkina Faso Th

  6. Runoff controlling factors in various sized catchments in a semi-arid Mediterranean environment in Spain

    NARCIS (Netherlands)

    Wit, A.M.W. de

    2001-01-01

    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 is s

  7. Polyacrylamide molecular weight and phosphogypsum effects on infiltration and erosion in semi-arid soils

    Science.gov (United States)

    Seal formation at the surface of semi-arid soils during rainstorms reduces soil infiltration rate (IR) and causes runoff and erosion. Surface application of dry anionic polyacrylamide (PAM) with high molecular weight (MW) has been found to be effective in stabilizing soil aggregates, and decreasing ...

  8. Necrophagous beetles associated with carcasses in a semi-arid environment in northeastern Brazil: implications for forensic entomology.

    Science.gov (United States)

    Mayer, Ana C G; Vasconcelos, Simão D

    2013-03-10

    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.

  9. The problems of over exploitation of aquifers in semi-arid areas: characteristics and proposals for mitigation

    Energy Technology Data Exchange (ETDEWEB)

    Rodriguez-Estrella, T.

    2014-06-01

    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)

  10. Do agrometeorological data improve optical satellite-based estimations of the herbaceous yield in Sahelian semi-arid ecosystems?

    DEFF Research Database (Denmark)

    Diouf, Abdoul Aziz; Hiernaux, Pierre; Brandt, Martin Stefan;

    2016-01-01

    Quantitative estimates of forage availability at the end of the growing season in rangelands are helpful for pastoral livestock managers and for local, national and regional stakeholders in natural resource management. For this reason, remote sensing data such as the Fraction of Absorbed Photosyn......Quantitative estimates of forage availability at the end of the growing season in rangelands are helpful for pastoral livestock managers and for local, national and regional stakeholders in natural resource management. For this reason, remote sensing data such as the Fraction of Absorbed...... evapotranspiration satellite gridded data to estimate the annual herbaceous yield in the semi-arid areas of Senegal. It showed that a machine-learning model combining FAPAR seasonal metrics with various agrometeorological data provided better estimations of the in situ annual herbaceous yield (R2 = 0.69; RMSE = 483...

  11. Land cover/land use change in semi-arid Inner Mongolia: 1992-2004

    Energy Technology Data Exchange (ETDEWEB)

    John, Ranjeet; Chen Jiquan; Lu Nan; Wilske, Burkhard, E-mail: ranjeet.john@utoledo.ed [Department of Environmental Sciences, University of Toledo, Toledo, OH 43606 (United States)

    2009-10-15

    The semi-arid grasslands in Inner Mongolia (IM) are under increasing stress owing to climate change and rapid socio-economic development in the recent past. We investigated changes in land cover/land use and landscape structure between 1992 and 2004 through the analysis of AVHRR and MODIS derived land cover data. The scale of analysis included the regional level (i.e. the whole of IM) as well as the level of the dominant biomes (i.e. the grassland and desert). We quantified proportional change, rate of change and the changes in class-level landscape metrics using the landscape structure analysis program FRAGSTATS. The dominant land cover types, grassland and barren, 0.47 and 0.27 million km{sup 2}, respectively, have increased proportionally. Cropland and urban land use also increased to 0.15 million km{sup 2} and 2197 km{sup 2}, respectively. However, the results further indicated increases in both the homogeneity and fragmentation of the landscape. Increasing homogeneity was mainly related to the reduction in minority cover types such as savanna, forests and permanent wetlands and increasing cohesion, aggregation index and clumpy indices. Conversely, increased fragmentation of the landscape was based on the increase in patch density and the interspersion/juxtaposition index (IJI). It is important to note the socio-economic growth in this fragile ecosystem, manifested by an increasing proportion of agricultural and urban land use not just at the regional level but also at the biome level in the context of regional climate change and increasing water stress.

  12. Modeled Impacts of Chronic Wasting Disease on White-Tailed Deer in a Semi-Arid Environment

    Science.gov (United States)

    Hewitt, David G.; DeYoung, Charles A.; DeYoung, Randy W.; Schnupp, Matthew J.

    2016-01-01

    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

  13. Integrated Modelling of Climate Change Impacts in an Irrigated, Semi-arid Catchment

    Science.gov (United States)

    Haslauer, C. P.; von Gunten, D.; Wöhling, T.; Rudolph, D. L.; Cirpka, O. A.

    2015-12-01

    Predicting the impacts of climate change on hydrological processes is a central challenge for water management. Commonly, studies on climate-change effects focus on surface flow and feed-backs between surface and subsurface flows are neglected frequently. Furthermore, changes in hydrological processes are generally not distributed realistically. Integrated catchment models, based on partial-differential-equations, have the potential of overcoming these difficulties. However, these models are complicated to use in realistic settings, notably because of their long simulation time. In this presentation, we demonstrate a successful application of an integrated catchment model (HydroGeoSphere) in a semi-arid catchment in north-east Spain. The study area recently underwent a transition to irrigated agriculture, which is reflected in our model evaluations conducted under varying irrigation conditions. To accelerate model calibration, we developed a novel calibration method based on a hierarchy of computational grids. The climate scenarios for the region are based on four regional climate models, which are downscaled using a weather generator. These scenarios are used to estimate climate change impacts on hydrologic parameters in different irrigation settings. The effects of climate change strongly depend on the presence of irrigation. Water table depth and low flows are more sensitive to climate change when irrigation is present, while peak flows exhibit a more pronounced response to climate in scenarios without irrigation. In addition to the climatic means, we examined the impacts of changes in drought conditions. We compare the outcomes of droughts predicted by our hydrological model with simpler approaches based on drought indices. We show that drought indices oversimplify future hydrological impacts of droughts and can result in biased estimation of drought impacts, especially if drought indices do not take temperature changes into account.

  14. Measurements of scattering and absorption properties of surface aerosols at a semi-arid site, Anantapur

    Science.gov (United States)

    Rama Gopal, K.; Balakrishnaiah, G.; Arafath, S. Md.; Raja Obul Reddy, K.; Siva Kumar Reddy, N.; Pavan Kumari, S.; Raghavendra Kumar, K.; Chakradhar Rao, T.; Lokeswara Reddy, T.; Reddy, R. R.; Nazeer Hussain, S.; Vasudeva Reddy, M.; Suresh Babu, S.; Mallikarjuna Reddy, P.

    2017-01-01

    Aerosol optical properties are continuously measured at a semi-arid station, Anantapur from June 2012 to May 2013 which describes the impact of surface aerosols on climate change over the region. Scattering coefficient (σsct) and absorption coefficient (σabs) are obtained from integrating Nephelometer and Aethalometer, respectively. Also, the single scattering albedo (ω0), Scattering/absorption Ångström exponents were examined during the period of study. Diurnal variations of σsct and σabs show a bi-peak pattern with two maxima and one minimum in a day. The largest values of σsct and σabs are obtained in winter while the lowest values are measured in monsoon. From the measurements σsct550 and σabs550 are found to be 110 ± 12.23 Mm- 1 and 33 ± 5.2 Mm- 1, respectively during the study period. An analysis of the ω0 suggests that there is a more absorbing fraction in the particle composition over the measurement site. The ω0 obtained in the surface boundary layer of Anantapur is below the critical value of 0.86 that determines the shift from cooling to warming. A relationship between scattering/absorption coefficients and scattering/absorption Ångström exponent and single scattering albedo is further examined. In order to understand the origins of the air masses in the study region, we performed seven-day back trajectory analyses based on the NOAA HYSPLIT model. These trajectories were computed at several altitudes (3000 m, 1500 m, and 500 m) for June 2012 and May 2013. These results put in evidence the need of efforts to reduce absorbing particles (black carbon) emissions to avoid the possible warming that would result from the reductions of the cooling aerosol only.

  15. An improved conceptual understanding of snowmelt and groundwater dynamics in the semi-arid Andes

    Science.gov (United States)

    Sproles, Eric; Hevia, Andres; Soulsby, Chris; Tetzlaff, Doerthe

    2016-04-01

    The contribution of snowmelt to groundwater has long been recognized as an important component of the hydrological cycle in semi-arid northern central Chile (29°-32°S). Despite its importance as a water resource, this transition to groundwater remains poorly understood. Climatically, the High Cordillera in northern central Chile receives approximately 10 times as much annual precipitation as the valley bottoms, falling almost exclusively as snow above 3500 m during the winter months. Geologically, the High Cordillera is characterized by steep topography and a highly dissected landscape underlain by bedrock. Groundwater stores in the mountain headwaters are assumed to be constrained to the valley bottoms. The current working hypothesis of watershed processes in the High Cordillera describes fluxes of spring melt moving through the hillslope via local flowpaths to valley aquifers that recharge streams throughout the headwater reaches. Previous studies in the region indicate Pre-Cordilleran aquifers, located in lower elevation dry ephemeral valleys, are hydrologically disconnected from the High Cordillera. These watersheds have no seasonal snowpack, and recharge occurs primarily during infrequent rain events. These isolated Pre-Cordilleran aquifers serve as an important water resource for rural residents and infrastructure. We present stable isotope, geochemical, and groundwater level data from the wet El Niño winter of 2015 that suggests a topographically disconnected aquifer in the Pre-Cordillera received considerable recharge from High Cordillera snowmelt. These novel findings are indicative of deep groundwater flow paths between the Pre- and High Cordillera during the wet winter and spring of 2015, and improve the conceptual understanding of hydrological processes in the region. Additionally, these results will directly benefit groundwater management in the Pre-Cordillera and better inform modeling efforts in the High Cordillera. While this study is limited to

  16. Soil water characteristic of a dense jujube plantation in the semi-arid hilly Regions of the Loess Plateau in China%黄土高原半干旱区山地密植枣林土壤水分特性研究

    Institute of Scientific and Technical Information of China (English)

    汪星; 周玉红; 汪有科; 卫新东; 郭旭新; 朱德兰

    2015-01-01

    针对陕北黄土丘陵区近年来形成的大规模枣林土壤水分研究薄弱的问题,本研究采用中子仪定位观测方法,探讨了山地密植枣林0~1000 cm土层范围的土壤水分特征变化规律。研究将黄土丘陵半干旱区的密植枣林土壤水分划分为活跃层、难恢复层和稳定层。活跃层是土壤0~200 cm土层,该层土壤水分具有明显的逐月动态变化规律,在枣树生育期内,5月是活跃层,土壤水分最干燥期,7月是土壤水分提升最明显期,10月是土壤水分最高期。土壤水分提升规律和枣树耗水规律一致,即在枣树生长旺盛时期,正是土壤水分提升最快的阶段;在枣树休眠结束和开始萌芽时枣林土壤水分出现最低值。枣林土壤水分难恢复层在200 cm以下,其深度取决于枣林年龄,林龄越大该层次越深,12年生密植枣林土壤耗水深度达到540 cm,其中难恢复层厚度为340 cm。难恢复层之下是土壤水分稳定层。研究认为密植枣林土壤耗水深度小于以往研究的刺槐、柠条和苜蓿等土壤水分消耗深度,山地密植枣林模式对今后研究人工林调控土壤水分有积极意义。%Jujube (Ziziphus jujube Mill. CV. Lizao) is an economically important tree fruit species cultivated in the semi-arid hilly regions of the loess plateau in China. A few studies focused on reporting soil water for this area;so this study aimed to quantify soil water characteristic within 0-1000 cm for dense jujube plantation, using the soil core method and neutron probe. The results showed that:(1) According to soil water dynamic change,the whole soil water profile was stratified into three layers:active layer,difficult re⁃covery layer,and stable layer. (2)The active layer ranged in the 0-200 cm;Soil water of this layer had ob⁃vious monthly dynamic change;In May, soil water content was the lowest during the whole growth stage (from May to October);soil water content

  17. Two-Source Energy Balance Model Evaluation for Mapping Evapotranspiration on the Semi- arid Southern High Plains

    Science.gov (United States)

    Gowda, P. H.; Chavez, J. L.; Colaizzi, P. D.; Evett, S. R.; Howell, T. A.; Copeland, K.

    2007-05-01

    Evapotranspiration (ET) is an essential component of the water balance and a major consumptive use of irrigation water and precipitation on cropland. In this study, we applied the Two-Source Energy Balance (T-SEB) model to estimate hourly ET from Landsat Thematic Mapper (TM) data for the semi-arid Southern High Plains of the United States where more than 90 percent of the groundwater withdrawals are used for irrigation. For this purpose, a Landsat TM image covering a major portion of the Southern High Plains (parts of Texas Panhandle and northeastern New Mexico) was acquired for 23 July 2006 for the overpass at 11:26 AM CST. Atmospheric correction on the TM imagery was done using MODTRAN, an atmospheric radiative transfer model. Comprehensive ground-truth data were collected to develop a detailed land use map showing major crops grown in the region. Performance of the T SEB model was evaluated by comparing mapped ET data with measured hourly ET data on five weighing lysimeters at Bushland, TX [35 Deg. 11' N, 102 Deg. 06' W; 1,170 m elevation MSL] managed by the Conservation and Production Research Laboratory, USDA-ARS. Lysimeter-measured ET rates varied from 0.24 to 0.71 mm/h. Comparison of estimated hourly mapped ET values with lysimetric measurements had an accuracy within 6% of the measured ET (r2=0.99), with a root mean squared error of 0.03 mm/h. These results support the use of the T-SEB model for the semi-arid Southern High Plains; however, more evaluation is needed for different agroclimatological conditions in the region.

  18. Hydrodynamics, vegetation transition and geomorphology coevolution in a semi-arid floodplain wetland.

    Science.gov (United States)

    Sandi, Steven; Rodriguez, Jose F.; Saco, Patricia M.; Riccardi, Gerardo; Wen, Li; Saintilan, Neil

    2016-04-01

    The Macquarie Marshes is a complex system of marshes, swamps and lagoons interconnected by a network of streams in the semi-arid region in north western NSW, Australia. The low-gradient topography of the site leads to channel breakdown processes where the river network becomes practically non-existent. As a result, the flow extends over large areas of wetland that later re-join and reform channels exiting the system. Vegetation in semiarid wetlands are often water dependent and flood tolerant species that rely on periodical floods in order to maintain healthy conditions. The detrimental state of vegetation in the Macquarie Marshes over the past few decades has been linked to decreasing inundation frequencies. Spatial distribution of flood tolerant overstory species such as River Red Gum and Black Box has not greatly changed since early 1990's, however; the condition of the vegetation patches shows a clear deterioration evidenced by terrestrial species encroachment on the wetland understory. On the other hand, areas of flood dependent species such as Water Couch and Common Reed have undergone complete succession to terrestrial species and dryland. 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 changes. Regular updates of stream network, floodplain surface elevations and vegetation coverage provide feedbacks to the hydrodynamic model. We presents also the development and assessment of transitional rules to determine if the water conditions have been met for different vegetation

  19. Physical-chemical determinant properties of biological communities in continental semi-arid waters.

    Science.gov (United States)

    da Rocha, Francisco Cleiton; de Andrade, Eunice Maia; Lopes, Fernando Bezerra; de Paula Filho, Francisco José; Filho, José Hamilton Costa; da Silva, Merivalda Doroteu

    2016-08-01

    Throughout human history, water has undergone changes in quality. This problem is more serious in dry areas, where there is a natural water deficit due to climatic factors. The aims of this study, therefore, were (i) to verify correlations between physical attributes, chemical attributes and biological metrics and (ii) from the biological attributes, to verify the similarity between different points of a body of water in a tropical semi-arid region. Samples were collected every 2 months, from July 2009 to July 2011, at seven points. Four physical attributes, five chemical attributes and four biological metrics were investigated. To identify the correlations between the physicochemical properties and the biological metrics, hierarchical cluster analysis (HCA) and canonical correlation analysis (CCA) were applied. Nine classes of phytoplankton were identified, with the predominance of species of cyanobacteria, and ten families of macroinvertebrates. The use of HCA resulted in the formation of three similar groups, showing that it was possible to reduce the number of sampling points when monitoring water quality with a consequent reduction in cost. Group I was formed from the waters at the high end of the reservoir (points P1, P2 and P3), group II by the waters from the middle third (points P4 and P5), and group III by the waters from the lower part of the reservoir (points P6 and P7). Richness of the phytoplanktons Cyanophyceae, Chorophyceae and Bacillariophyceae was the attribute which determined dissimilarity in water quality. Using CCA, it was possible to identify the spatial variability of the physicochemical attributes (TSS, TKN, nitrate and total phosphorus) that most influence the metrics of the macroinvertebrates and phytoplankton present in the water. Low macroinvertebrate diversity, with a predominance of indicator families for deterioration in water quality, and the composition of phytoplankton showing a predominance of cyanobacteria, suggests greater

  20. The role of upland wetlands in modulating snowmelt runoff in the semi-arid Andes

    Science.gov (United States)

    Hevia, Andres; Sproles, Eric; Soulsby, Chris; Tetzlaff, Doerthe

    2016-04-01

    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.

  1. 黄土高原半干旱区不同覆膜连作玉米产量的水分承载时限研究%The Time Loading Limitation of Continuous Cropping Maize Yield Under Different Plastic Film Mulching Modes in Semi-Arid Region of Loess Plateau of China

    Institute of Scientific and Technical Information of China (English)

    谢军红; 柴强; 李玲玲; 张仁陟; 牛伊宁1; 罗珠珠; 蔡立群

    2015-01-01

    experiment in the second year, and it was 29.6%, 27.5% and 23.9% lower in the third year, this continuous soil water decrease practice resulted in soil water deficiency. With the prolongation of the time of continuous cultivation, soil desiccation appeared and has a negative effect on soil water sustainable use.[Conclusion]Under the same rainfall conditions, the completely mulched alternating narrow and wide ridges with furrow planting had a significant effect on increasing the yield, benefit and the WUE. Taking the sustainable use of water into account, 2 years is a suitable period of continuous cropping for the completely mulched alternating narrow and wide ridges with furrow planting, and 3 years is a suitable period of continuous cropping for complete mulching and flat-planting, half-mulching and flat-planting, flat-planting without mulching, respectively, in semi-arid region of Loess Plateau.%【目的】以黄土高原半干旱区有限降水持续高效利用为目标,研究不同覆膜方式下连作玉米(ZeaMay L.)的产量表现和水分利用特征,揭示其增产机理,明确不同覆膜方式下有利于土壤水分持续高效利用的连作年限,为试区高产、水分高效持续利用型玉米连作技术提供理论依据。【方法】以田间定位试验为基础,量化连作玉米农田土壤水分的年际平衡关系、产量稳定性;以持续高产和收获期不发生土壤干燥化为依据,确定适用于不同覆膜方式的玉米连作年限。【结果】3年试验结果表明,全膜双垄沟播具有良好的保墒、提高土壤水分有效性,利于协调关键生育时期土壤-作物的水分供需关系,提高产量和水分利用效率的作用。与半膜平作处理相比,全膜双垄沟播玉米的籽粒产量、水分利用效率分别提高了41.8%和33.4%,生物产量、单位耗水的干物质累积量、总产值、净产值、毫米水产值和产投比分别提高了21.8%、12.3%、31.2%、27.8%

  2. Estrutura genética espacial de duas populações naturais de Myracrodruon urundeuva M. Allemão na região semi-árida, Brasil Spacial genotype structure of two natural populations of Myracrodruon urundeuva M. Allemão in a semi-arid region of Brazil

    Directory of Open Access Journals (Sweden)

    Cristina Maria Batista de Lacerda

    2003-04-01

    Full Text Available Para determinar se a distribuição espacial dos genótipos é aleatória ou se está estruturada, utilizou-se a autocorrelação espacial dos genótipos para investigar dados alozímicos de duas populações naturais de Myracrodruon urundeuva do semi-árido brasileiro (Estação Ecológica do Seridó/RN, com 1.166,38/ha e Sítio Mata dos Alves/PB com 84/ha. A primeira população encontra-se em áreas mais preservadas, enquanto a segunda está em uma área fragmentada. O programa utilizado foi o "Autocorr". A autocorrelação estimada para os locos polimórficos foi realizada nos indivíduos adultos. Foram analisados dois alelos na Estação Ecológica do Seridó e quatro no Sítio Mata dos Alves. Utilizaram-se de três métodos para o pareamento de indivíduos a serem comparados: conexão de Gabriel (Ig, vizinho mais próximo (Ivmp e comparações dentro de classes de distâncias preestabelecidas. Os resultados obtidos para Ig e Ivmp (Pgm-2: 0,032 e 0,236; Est-1: 0,263 e 0,242, respectivamente na estação ecológica e Ig e Ivmp (Pgm-1: -0,349 e -0,288; Pgm-2: -0,341 e-0,278; Est-1: -0,349 e -0,284 e Mdh-1: -0,345 e 0,282, respectivamente no sítio não mostraram a presença de estruturação genética espacial, o que possibilita pressupor que exista uma distribuição aleatória dos genótipos dentro delas. O mesmo foi detectado para as comparações dentro de classes de distâncias preestabelecidas. Os resultados mantiveram o mesmo padrão encontrado para algumas populações naturais de espécies arbóreas tropicais já estudadas.To determine whether genotype spacial distribution is random or structured, spacial genotypic autocorrelation was used to compare two natural populations of Myracrodruon urundeuva in the semi-arid region of Northeastern Brazil (Estação Ecológica do Seridó/RN - 1166,38/ha and Sítio Mata dos Alves/PB - 84/ha. The former is characteristic of preserved areas, while the latter is found in areas with marked

  3. Qualitative soil moisture assessment in semi-arid Africa: the role of experience and training on inter-rater reliability

    Directory of Open Access Journals (Sweden)

    M. Rinderer

    2015-03-01

    Full Text Available 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.

  4. Qualitative soil moisture assessment in semi-arid Africa - the role of experience and training on inter-rater reliability

    Science.gov (United States)

    Rinderer, M.; Komakech, H. C.; Müller, D.; Wiesenberg, G. L. B.; Seibert, J.

    2015-08-01

    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.

  5. Qualitative soil moisture assessment in semi-arid Africa: the role of experience and training on inter-rater reliability

    Science.gov (United States)

    Rinderer, M.; Komakech, H.; Müller, D.; Seibert, J.

    2015-03-01

    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.

  6. Perched groundwater-surface interactions and their consequences in stream flow generation in a semi-arid headwater catchment

    Science.gov (United States)

    Molenat, Jerome; Bouteffeha, Maroua; Raclot, Damien; Bouhlila, Rachida

    2013-04-01

    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.

  7. Development and Application of Grid-GA Model in a Semi-Humid and Semi-Arid Basin

    Science.gov (United States)

    Wang, L.; Li, Z.; Bao, H.; Yu, Z.

    2009-12-01

    Modeling the hydrologic processes in semi-arid and semi-humid basins is specially challenging due to the specific characteristics of these basins. In this paper, combining with GIS technology and DEM, the Grid- and Green-Ampt infiltration approach-based distributed hydrologic model of the runoff-production in excess infiltration is developed (Grid-GA model). In Grid-GA model, the Green-Ampt infiltration approach has improved in three parts: (1) the effective hydraulic conductivity of the wetting front at saturation, is power function decaying with the depth of the wetting front; (2) F, the cumulative infiltration, is modified at the end of every time step; (3) the moisture content rate of the soil, is redistribution during the infiltration process. In flow concentration formation, there are kinematic wave approach for un-channel grid and Muskingum approach for channel grid. The model described that includes vegetation and root interception, evapotranspiration, and runoff generation via the excess infiltration mechanism, as well as subsurface via the Darcian approach used by TOPMODEL, runoff concentration, and flow routing. The water exchange among grids within the watershed and the runoff routing along the river drainage networks are taken into consideration in the model. The Grid-GA model is applied to Gaoli basin in Yi River, a tributary of the Yishusi Watershed, with an area of 552 km2 for flood simulation. The results show that the model performs well in the simulation and can be used for flood forecasting in the semi-humid and semi-arid region.

  8. 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;

    2015-01-01

    The growth rate of atmospheric carbon dioxide (CO2) concentrations since industrialization is characterized by large interannual variability, mostly resulting from variability in CO2 uptake by terrestrial ecosystems (typically termed carbon sink). However, the contributions of regional ecosystems...... 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....

  9. Tillage for soil and water conservation in the semi-arid tropics

    OpenAIRE

    Hoogmoed, W.B.

    1999-01-01

    Soil tillage is the manipulation of soil which is generally considered as necessary to obtain optimum growth conditions for a crop. In the same time the resulting modification of soil structure has serious implications for the behaviour of the soil to erosive forces by water and wind. In Chapter 1 an introduction is given to the most important aspects: the objectives of tillage, the conflicting requirements set to tillage, the characteristics of soil and water conservation in the semi-arid tr...

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

    OpenAIRE

    Magombedze, Chris

    2006-01-01

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

  11. L'économie de la gestion des risques en zone semi-aride

    NARCIS (Netherlands)

    Dijk, van J.W.M.; Tielekes, E.; Schlecht, E.; Hiernaux, P.

    2001-01-01

    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

  12. Timing and climatic drivers for glaciation across semi-arid western Himalayan-Tibetan orogen

    Science.gov (United States)

    Dortch, Jason M.; Owen, Lewis A.; Caffee, Marc W.

    2013-10-01

    Mapping and forty-seven new 10Be ages help define the timing of glaciation in the Ladakh and Pangong Ranges in Northwest India. Five new local glacial stages are defined for the Ladakh Range. From oldest to youngest these include: the Ladakh-4 glacial stage at 81 ± 20 ka; the Ladakh-3 glacial stage (not dated); the Ladakh-2 glacial stage at 22 ± 3 ka; the Ladakh-1 glacial stage (not dated); and the Ladakh Cirque glacial stage at 1.8 ± 0.4 ka. Three local glacial stages are defined for the Pangong Range, which include: the Pangong-2 glacial stage at 85 ± 15 ka; the Pangong-1 glacial stage at 40 ± 3 ka; and the Pangong Cirque glacial stage at 0.4 ± 0.3 ka. The new 10Be ages are combined with 645 recalculated 10Be ages from previous studies to develop the first regional framework of glaciation across the dryland regions of the Greater Himalaya, Transhimalaya, Pamir and Tian Shan at the western end of the Himalayan-Tibetan orogen. Nineteen regional glacial stages are recognized that are termed semi-arid western Himalayan-Tibetan stages (SWHTS). These include: SWHTS 9 at 311 ± 32 ka; SWHTS 7 at 234 ± 44 ka [tentative]; SWHTS 6 at 146 ± 18 ka; SWHTS 5E at 121 ± 11 ka; SWHTS 5A at 80 ± 5 ka; SWHTS 5A- at 72 ± 8 ka; SWHTS 4 at 61 ± 5 ka; SWHTS 3 at 46 ± 4 ka; SWHTS 2F at 30 ± 3 ka; SWHTS 2E at 20 ± 2 ka; SWHTS 2D at 16.9 ± 0.7 ka; SWHTS 2C at 14.9 ± 0.8 ka; SWHTS 2B at 13.9 ± 0.5 ka; SWHTS 2A at 12.2 ± 0.8 ka; SWHTS 1E at 8.8 ± 0.3 ka [tentative]; SWHTS 1D at 6.9 ± 0.2 ka [tentative]; SWHTS 1C at 3.8 ± 0.6 ka; SWHTS 1B at 1.7 ± 0.2 ka; and SWHTS 1A at 0.4 ± 0.1 ka. Regional glacial stages older than 21 ka are broadly correlated with strong monsoons. SWHTS that are 21 ka or younger, have smaller uncertainties and broadly correlate with global ice volume given by marine Oxygen Isotope Stages, and northern hemisphere climatic events (Oldest Dryas, Older Dryas, Younger Dryas, Roman Humid Period, and Little Ice Age).

  13. Iranian speleothems: Investigating Quaternary climate variability in semi-arid Western Asia

    Science.gov (United States)

    Carolin, Stacy; Morgan, Jacob; Peckover, Emily; Walker, Richard; Henderson, Gideon; Rowe, Peter; Andrews, Julian; Ersek, Vasile; Sloan, Alastair; Talebian, Morteza; Fattahi, Morteza; Nezamdoust, Javad

    2016-04-01

    Rapid population growth and limited water supply has highlighted the need for vigorous water resource management practices in the semi-arid regions of Western Asia. One significant unknown in this discussion is the future change in rainfall amount due to the consequential effects of today's greenhouse gas forcing on the regional climate system. Currently, there is little paleoclimate proxy data in Western Asia to extend climate records beyond the limits of the instrumental period, leaving scant evidence to investigate the system's response to various climate forcings on different timescales. Here we present a synthesis of speleothem climate records across northern Iran, from the wetter climate of the Alborz and Zagros mountain ranges to the dry northeast, in order to investigate the magnitude of past climate variability and the forcings responsible. The stalagmites collected from the west and north-central mountain ranges, areas with ~200-400mm mean annual precipitation mostly falling within the fall-winter-spring months, all demonstrate growth limited to the interglacial periods of the Quaternary. We present overlapping Holocene stable isotope records with a complementary trace element record to assist in interpreting the isotopic variability. One of the records is sampled at <4yr resolution and spans 3.7-5.3 kyBP, a contested period of catastrophic droughts that allegedly eradicated civilizations in areas of the near East. Imposed upon decadal-scale variability, the record reveals a 1,000-yr gradual trend toward enriched stable oxygen isotope values, interpreted as a trend toward drier conditions, which ends with an abrupt 300-yr cessation in growth beginning at 4.3 kyBP, coincident with the so-called 4.2 kyBP drought event. From the northeast Iranian plateau, we present a new stalagmite record that spans the penultimate deglaciation and Stages 5e-5a. This region presently receives limited rain annually (~100-300mm/yr, regularly falling between November and May

  14. Spatial distribution of rock glaciers in the semi-arid Andes of Argentina

    Science.gov (United States)

    Blöthe, Jan Henrik; Halla, Christian; Schrott, Lothar; Götz, Joachim; Trombotto, Dario

    2016-04-01

    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

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

    Science.gov (United States)

    Wolaver, B. D.

    2007-12-01

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

  16. Permafrost Distribution Modeling in the Semi-Arid Chilean Andes

    OpenAIRE

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

    2016-01-01

    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...

  17. Evaluation of diets containing silage of maniÃoba (Manihot pseudoglaziovii Pax. Et. K. Hoffman) during the final stage of goats in the brazilian semi-arid region

    OpenAIRE

    Fernando Thomaz Medina

    2005-01-01

    The present work aimed to evaluate the consumption, the digestibility of nutrients, the daily average weight gain, the nutriment conversion, as well as the weight and yield of carcass of goats being held in confinement during the final stage, receiving diets containing silage of manioc associated to different energy sources. 15 goats without defined racial standard, not castrated, with initial average life weight of 21,0 kg, were allocated in delineation in casual blocks, with three tre...

  18. Spatiotemporal modelling of groundwater extraction in semi-arid central Queensland, Australia

    Science.gov (United States)

    Keir, Greg; Bulovic, Nevenka; McIntyre, Neil

    2016-04-01

    The semi-arid Surat Basin in central Queensland, Australia, forms part of the Great Artesian Basin, a groundwater resource of national significance. While this area relies heavily on groundwater supply bores to sustain agricultural industries and rural life in general, measurement of groundwater extraction rates is very limited. Consequently, regional groundwater extraction rates are not well known, which may have implications for regional numerical groundwater modelling. However, flows from a small number of bores are metered, and less precise anecdotal estimates of extraction are increasingly available. There is also an increasing number of other spatiotemporal datasets which may help predict extraction rates (e.g. rainfall, temperature, soils, stocking rates etc.). These can be used to construct spatial multivariate regression models to estimate extraction. The data exhibit complicated statistical features, such as zero-valued observations, non-Gaussianity, and non-stationarity, which limit the use of many classical estimation techniques, such as kriging. As well, water extraction histories may exhibit temporal autocorrelation. To account for these features, we employ a separable space-time model to predict bore extraction rates using the R-INLA package for computationally efficient Bayesian inference. A joint approach is used to model both the probability (using a binomial likelihood) and magnitude (using a gamma likelihood) of extraction. The correlation between extraction rates in space and time is modelled using a Gaussian Markov Random Field (GMRF) with a Matérn spatial covariance function which can evolve over time according to an autoregressive model. To reduce computational burden, we allow the GMRF to be evaluated at a relatively coarse temporal resolution, while still allowing predictions to be made at arbitrarily small time scales. We describe the process of model selection and inference using an information criterion approach, and present some

  19. High spatial resolution remote sensing imagery improves GPP predictions in disturbed, semi-arid woodlands

    Science.gov (United States)

    Krofcheck, D. J.; Eitel, J.; Vierling, L. A.; Schulthess, U.; Litvak, M. E.

    2012-12-01

    Climate across the globe is changing and consequently the productivity of terrestrial vegetation is changing with it. Gross primary productivity (GPP) is an integral part of the carbon cycle, yet challenging to measure everywhere, all the time. Efforts to estimate GPP in the context of climate change are becoming continually more salient of the need for models sensitive to the heterogeneous nature of drought and pest induced disturbance. Given the increased availability of high spatial resolution remotely sensed imagery, their use in ecosystem scale GPP estimation is becoming increasingly viable. We used a simple linear model with inputs derived from RapidEye time series data (5 meter spatial resolution) as compared to MODIS inputs (250 meter spatial resolution) to estimate GPP in intact and girdled PJ woodland to simulate drought and pest induced disturbance. An area equal to the MODIS pixels measured was aggregated using RapidEye data centered on the flux towers for comparison purposes. We generated four model runs, two using only MODIS or RapidEye spectral vegetation indices (VIs) and two using MODIS and RapidEye VIs combined at both the control and disturbed tower site. Our results suggest that for undisturbed regions, MODIS derived VIs perform better than the higher spatial resolution RapidEye VIs when a moisture sensitive index is incorporated into the model (RMSE of 17.51for MODIS vs. 22.71 for RapidEye). Modeling GPP in disturbed regions however benefits from the inclusion of high spatial resolution data (RMSE of 14.83 for MODIS vs. 14.70 for RapidEye). This discrepancy may have to do with the disparate scale of a MODIS pixel and the size of the tower fetch. Our results suggest that the best source of VI's for the modeling GPP in semi-arid woodlands depends on the level of disturbance in the landscape. Given that the rate and extent of drought and insect induced mortality events in terrestrial forests are projected to increase with our changing climate

  20. Effects of Phosphorus Application in Different Soil Layers on Root Growth, Yield, and Water-Use Efifciency of Winter Wheat Grown Under Semi-Arid Conditions

    Institute of Scientific and Technical Information of China (English)

    KANG Li-yun; YUE Shan-chao; LI Shi-qing

    2014-01-01

    Deep phosphorus application can be a usefull measure to improve crops’ performance in semi-arid regions, but more knowledge of both its general effects and effects on speciifc crops is required to optimize treatments. Thus, the aims of this study were to evaluate the effects of phosphorus (P) application at different soil layers on root growth, grain yield, and water-use efifciency (WUE) of winter wheat grown on the semi-arid Loess Plateau of China and to explore the relationship between root distribution and grain yield. The experiment consisted of four P treatments in a randomized complete block design with three replicates and two cultivars: one drought-sensitive (Xiaoyan 22, XY22) and one drought-tolerant (Changhan 58, CH58). The four P treatments were no P (control, CK), surface P (SP), deep P (DP), and deep-band P application (DBP). CH58 produced larger and deeper root systems, and had higher grain yields and WUE, under the deep P treatments (DP and DBP) than under SP, clearly showing that deep P placement had beneifcial effects on the drought-tolerant cultivar. In contrast, the grain yield and root growth of XY22 did not differ between DP or DBP and SP treatments. Further, root dry weight (RW) and root length (RL) in deep soil layer (30-100 cm) were closely positively correlated with grain yield and WUE of CH58 (but not XY22), highlighting the connections between a well-developed subsoil root system and both high grain yield and WUE for the drought-tolerant cultivar. WUE correlated strongly with grain yield for both cultivars (r=0.94,P<0.001). In conclusion, deep application of P fertilizer is a practical and feasible means of increasing grain yield and WUE of rainfed winter wheat in semi-arid regions, by promoting deep root development of drought-tolerant cultivars.

  1. Scarce data in hydrology and hydrogeology: Estimation and modelling of groundwater recharge for a numerical groundwater flow model in a semi-arid to arid catchment

    Science.gov (United States)

    Gräbe, Agnes; Schulz, Stephan; Rödiger, Tino; Kolditz, Olaf

    2013-04-01

    Water resources are strongly limited in semi-arid to arid regions and groundwater constitutes often the only possibility for fresh water for the population and industry. An understanding of the hydrological processes and the estimation of magnitude of water balance parameters also includes the knowledge of processes of groundwater recharge. For the sustainable management of water resources, it is essential to estimate the potential groundwater recharge under the given climatic conditions. We would like to present the results of a hydrological model, which is based on the HRU- concept and intersected the parameters of climatic conditions, topography, geology, soil, vegetation and land use to calculate the groundwater recharge. This model was primarily developed for humid area applications and has now been adapted to the regional conditions in the semi-arid to arid region. It was quite a challenge to understand the hydrological processes in the semi-arid to arid study area and to implement those findings (e.g. routing [Schulz (in prep.)]) into the model structure. Thus we compared the existing approaches for groundwater recharge estimations (chloride mass balance [Marei et. al 2000], empirical relations such as rainfall and base flow-relation [Goldschmidt 1960; Guttman 2000; Hughes 2008; Issar 1993; Lerner 1990; De Vries et. al 2002]) with the results of our numerical model. References: De Vries, J. J., I. Simmers (2002): Groundwater recharge: an overview of processes and challenges. Hydrogeology Journal (2002) 10: 5-17. DOI 10.1007/s10040-001-0171-7. Guttman, J., 2000. Multi-Lateral Project B: Hydrogeology of the Eastern Aquifer in the Judea Hills and Jordan Valley. Mekorot Water Company, Report 468, p. 36. Hughes, A. G., M. M. Mansour, N. S. Robins (2008): Evaluation of distributed recharge in an upland semi-arid karst system: the West Bank Mountain Aquifer, Middle East. Hydrogeology Journal (2008) 16: 845-854. DOI 10.1007/s10040-008-0273-6 Issar, A. S. (1993

  2. Agricultural sustainability in the semi-arid Near East

    Directory of Open Access Journals (Sweden)

    F. Hole

    2007-05-01

    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.

  3. Agricultural sustainability in the semi-arid Near East

    Directory of Open Access Journals (Sweden)

    F. Hole

    2006-07-01

    Full Text Available Agriculture began in the eastern Mediterranean Levantine Corridor about 11 000 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 use, 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 support 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.

  4. drought assessment using Standard precipitation Index in semi arid conditions

    Science.gov (United States)

    Bargaoui, Zoubeida

    2015-04-01

    The Gamma distribution is classically fitted at monthly resolution to assess drought occurrence with respect to precipitation series. SPI estimation reports deviations from normal situations and allows the classification of months from extremely wet to extremely dry. However in case where time series contain zeros (no rainfall observed for some months) the choice of Gamma distribution is not appropriate. The objective of this study is compare Gamma distribution results to the loi des fuites distribution as alternative (Ref : Parent et al., Rev. Statistique Appliquée, 2006, LIV (4), 85-111 ). A network composed by 43 rainfall stations from the extreme North region of Tunisia (Mediterranean façade) using long series records (exceeding 30 years) is adopted to develop the methodology. the distributions for the 1- month, 3-months totals as well as 6 months totals and 12-months totals are adjusted station by station for both distributions and SPI-1, SPI-3, SPI-6 , SPI-12 are computed. It is found that especially for SPI-1 and SPI-3 that reflect meteorological drought, the decision status is well related to the underlined distribution which results in many operational concerns.

  5. Radical scavenging, antioxidant and cytotoxic activity of Brazilian Caatinga plants.

    Science.gov (United States)

    David, Juceni P; Meira, Marilena; David, Jorge M; Brandão, Hugo N; Branco, Alexsandro; de Fátima Agra, M; Barbosa, M Regina V; de Queiroz, Luciano P; Giulietti, Ana M

    2007-04-01

    Extracts of 32 plants from the Brazilian northeastern semi-arid region called Caatinga were evaluated through DPPH radical scavenging assay, beta-carotene bleaching, and brine shrimp lethality tests (BST). Among the extracts studied Byrsonima cf. gardneriana, Mascagnia coriacea, Cordia globosa, Diodia apiculata and Hypenia salzmannii showed the highest activities in DPPH radical scavenging test. In the beta-carotene bleaching test the highest activities were observed for Passiflora cincinnata, Chamaecrista repens, B. cf. gardneriana, Rollinia leptopetala, Serjania glabrata, Diospyros gaultheriifolia, C. globosa, Mimosa ophtalmocentra, M. coriacea and Lippia cf. microphylla. In contrast, R. leptopetala, Zornia cf. brasiliensis and Leonotis nepetifolia were the most active species in the BST.

  6. Influence of Vegetation Cover on Rain Pulse Responses in Semi-Arid Savannas in Central Texas

    Science.gov (United States)

    Litvak, M.; Heilman, J.; McInnes, K.; Thijs, A.; Kjelgaard, J.

    2007-12-01

    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

  7. Evaporative loss from irrigated interrows in a highly advective semi-arid agricultural area

    Science.gov (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.

    2012-12-01

    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

  8. Simple, spatial and predictive approach for cereal yield prediction in the semi-arid areas

    Science.gov (United States)

    Toumi, Jihad; Khabba, Said; Er-Raki, Salah; Le page, Michel; Chahbi Bellakanji, Aicha; Lili Chabaane, Zohra; Ezzahar, Jamal; Zribi, Mehrez; Jarlan, Lionel

    2016-04-01

    The objective is to develop a simple, spatial and predictive approach of dry matter (DM) and grain yield (GY) of cereal in the semi-arid areas. The proposed method is based on the three efficiencies model of Monteith (1972). This approach summarizes the transformation of solar radiation to the dry matter (DM) by the climate (ɛc), interception (ɛi) and conversion (ɛconv) efficiencies. The method combines the maximum of ɛi and ɛconv (noted ɛimax and ɛconvmax) into a single parameter denoted ɛmax, calculating as a function of cumulating growing degree day (CGDD). Also, the stress coefficient ks, which affects the conversion of solar radiation to the biomass was calculated by the surface temperature or the water balance at the root zone. In addition, the expression of ks has been improved by the consideration of the results achieved by deficit irrigation (AquaCrop and STICS models) which showed that the value of ks from 0.7 to 1 didn't affect significantly the cereal production. For the partitioning of the dry matter developed, between straw and grain, the method proposed calculates a variable Harvest Index coefficient (HI). HI is deducted from CGDD and HI0max (maximal final harvest Index in the region of study). Finally, the approach calculates DM depending Satellite Information (NDVI and surface temperature Ts) and climatic data (solar radiation and air temperature). In the case of no availability of Ts, the amount of irrigation is required to calculate ks. Until now, the developed model has been calibrated and validated on the irrigated area R3, located 40 Km east of Marrakech. The evolutions of DM and GY were reproduced satisfactorily. R2 and RMSE are respectively 0.98 and 0.35 t/ha and 0.98 and 0.19 t/ha, respectively. Currently, additional tests are in progress on data relating to the Kairouan plain of Tunisia.

  9. Understanding environmental drivers in the regulation of soil respiration dynamics after fire in semi-arid ecosystems

    Science.gov (United States)

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

    2016-04-01

    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

  10. 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

    Directory of Open Access Journals (Sweden)

    Silvia Regina Dias Médici Saldiva

    2010-04-01

    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

  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

    Directory of Open Access Journals (Sweden)

    Luciano A. Pimentel

    2007-01-01

    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. VNIR-SWIR-TIR hyperspectral airborne campaign for soil and sediment mapping in semi-arid south african environments

    Science.gov (United States)

    Milewski, Robert; Chabrillat, Sabine; Eisele, Andreas

    2016-04-01

    Airborne hyperspectral remote sensing techniques has been proven to offer efficient procedures for soil and sediment mineralogical mapping in arid areas on larger scales. Optical methods based on traditional remote sensing windows using the solar reflective spectral wavelength range from the visible-near infrared (VNIR: 0.4-1.1 μm) to the short-wave infrared region (SWIR: 1.1-2.5 μm) allow mapping of common soil properties such as iron oxides, textural characteristics and organic carbon. However, soil mapping in semi-arid environments using VNIR-SWIR is currently limited due to specific spectral characteristics. Challenges appear in such environments due to the common presence of sandy soils (coarse textured) which grain size distribution is driven by the dominant mineral, quartz (SiO2), and which lacks any distinctive Si-O bond related spectral features within the VNIR-SWIR. Furthermore, another challenge is represented by the common presence of other specific spectral features due to different salts (gypsum, halite) or coatings of different forms (cyanobacteria, iron-oxides and/or -oxyhydroxides) for which few studies exists or that oft prevent detection of any other potential spectral feature of e.g. soil organics. In this context, more methodological developments are needed to overcome current limitations of hyperspectral remote sensing for arid areas, and to extent its scope using the thermal infrared (TIR) wavelength region within the atmospheric window between 8 and 14 μm (longwave infrared). In 2015 an extensive VNIR-SWIR-TIR airborne hyperspectral dataset consisting of HySpex-VNIR, HySpex-SWIR (NEO) and Hyper-Cam (TELOPS) data has been acquired in various Namibian and South African landscapes part of the Dimap/GFZ campaign in the frame of the BMBF-SPACES Geoarchive project. Research goals are 1) to demonstrate the capabilities to extract information from such a dataset and 2) to demonstrate the potential of advanced hyperspectral remote sensing

  13. Recovery of microbial community structure and functioning after wildfire in semi-arid environments: optimising methods for monitoring and assessment

    Science.gov (United States)

    Muñoz-Rojas, Miriam; Martini, Dylan; Erickson, Todd; Merritt, David; Dixon, Kingsley

    2015-04-01

    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

  14. A max-to-min technique for making projections of NDVI change in semi-arid Africa for food security early warning

    Science.gov (United States)

    Brown, M. E.; Funk, C. C.

    2005-12-01

    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.

  15. Eutrophication and sedimentation patterns in complete exploitation of water resources scenarios: an example from Northwestern semi-arid Mexico.

    Science.gov (United States)

    Sánchez-Carrillo, Salvador; Alatorre, Luis C; Sánchez-Andrés, Raquel; Garatuza-Payán, Jaime

    2007-09-01

    Water requirements to supply human needs lead water stakeholders to store more water during surplus periods to fulfil the demand during--not only--scarcity periods. At the reservoirs, mostly those in semi-arid regions, water level then fluctuates extremely between rises and downward during one single year. Besides of water management implications, changes on physical, chemical and biological dynamics of these drawdown and refilling are little known yet. This paper shows the results, throughout a year, on solids, nutrients (N and P), chlorophyll-a, and sedimentation changes on the dynamics, when the former policy was applied in a reservoir from the semi-arid Northwestern Mexico. Water level sinusoidal trend impinged changes on thermal stratification and mixing, modifying nutrient cycling and primary producer responses. According to nitrogen and phosphorus concentration as well as chlorophyll-a, reservoir was mesotrophic, becoming hypertrophic during drawdown. Nutrient concentrations were high (1.22 +/- 0.70 and 0.14 +/- 0.12 mg P l(-1)), increasing phosphorus and lowering N:P significantly throughout the study period, although no intensive agricultural, no urban development, neither industrial activities take place in the watershed. This suggests nutrient recycling complex mechanisms, including nutrient release from the sediment-water interface as the main nutrient pathway when shallowness, at the same time as mineralization, increases. Outflows controlled nitrogen and phosphorus availability on the ecosystem while organic matter depended on river inflows. As on other subtropical aquatic ecosystems, nitrogen limited primary productivity (Spearman correlation R = 0.75) but chlorophyll-a seasonal pattern showed an irregular trend, prompting other no-nutrient related limitants. Shallowness induced a homogeneous temporal pattern on water quality. This observed temporal variability was mainly explained statistically by changes on solids (mineral and organic), chlorophyll

  16. Applicability of passive compost bioreactors for treatment of extremely acidic and saline waters in semi-arid climates.

    Science.gov (United States)

    Biermann, Vera; Lillicrap, Adam M; Magana, Claudia; Price, Barry; Bell, Richard W; Oldham, Carolyn E

    2014-05-15

    Extremely acidic and saline groundwater occurs naturally in south-western Australia. Discharge of this water to surface waters has increased following extensive clearing of native vegetation for agriculture and is likely to have negative environmental impacts. The use of passive treatment systems to manage the acidic discharge and its impacts is complicated by the region's semi-arid climate with hot dry summers and resulting periods of no flow. This study evaluates the performance of a pilot-scale compost bioreactor treating extremely acidic and saline drainage under semi-arid climatic conditions over a period of 2.5 years. The bioreactor's substrate consisted of municipal waste organics (MWO) mixed with 10 wt% recycled limestone. After the start-up phase the compost bioreactor raised the pH from ≤3.7 to ≥7 and produced net alkaline outflow for 126 days. The bioreactor removed up to 28 g/m(2)/d CaCO3 equivalent of acidity and acidity removal was found to be load dependent during the first and third year. Extended drying over summer combined with high salinity caused the formation of a salt-clay surface layer on top of the substrate, which was both beneficial and detrimental for bioreactor performance. The surface layer prevented the dehydration of the substrate and ensured it remained waterlogged when the water level in the bioreactor fell below the substrate surface in summer. However, when flow resumed the salt-clay layer acted as a barrier between the water and substrate decreasing performance efficiency. Performance increased again when the surface layer was broken up indicating that the negative climatic impacts can be managed. Based on substrate analysis after 1.5 years of operation, limestone dissolution was found to be the dominant acidity removal process contributing up to 78-91% of alkalinity generation, while bacterial sulfate reduction produced at least 9-22% of the total alkalinity. The substrate might last up to five years before the limestone

  17. Soil carbon changes after plantation of autochthonous species in a semi-arid Mediterranean old-field in Sardinia

    Science.gov (United States)

    de Dato, Giovanbattista; de Angelis, Paolo

    2010-05-01

    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).

  18. The Brazilian semi-arid environment influences the physiological responses of goats

    Directory of Open Access Journals (Sweden)

    Laylson da Silva Borges

    2015-12-01

    Full Text Available In this review, we compile information about the physiologic responses of goats to north-eastern Brazil’s semiarid environment and suggest some strategies to avoid the thermal discomfort of these small ruminants. Due to recent weather changes, the number of studies seeking to improve animal welfare has intensified to minimize the economic losses on animal production in the tropics. Among the climatic variables, the high room temperature, air humidity, and direct solar radiation are the main causes of physiological discomfort in animals that decrease their productivity. Therefore, it is very important to study the components that interact in the thermoregulation process, the consequences of disequilibrium in this process, and ways to ease these effects, aiming to provide thermal comfort to and seek the animal welfare of the animals. Therefore, it is essential to know the interaction between animals and the environment and the adaptability of the species and breeds that are exploited to make decisions about farming systems and management strategies to maximize productivity.

  19. On the potential for regolith control of fluvial terrace formation in semi-arid escarpments

    Science.gov (United States)

    Norton, K. P.; Schlunegger, F.; Litty, C.

    2016-02-01

    Cut-fill terraces occur throughout the western Andes, where they have been associated with pluvial episodes on the Altiplano. The mechanism relating increased rainfall to sedimentation is, however, not well understood. Here, we apply a hillslope sediment model and reported cosmogenic nuclide concentrations in terraces to examine terrace formation in semi-arid escarpment environments. We focus on the Pisco river system in western Peru in order to determine probable hillslope processes and sediment transport conditions during phases of terrace formation. Specifically, we model steady-state and transient hillslope responses to increased precipitation rates. The measured terrace distribution and sediment agree with the transient predictions, suggesting strong climatic control on the cut-fill sequences in western Peru primarily through large variations in sediment load. Our model suggests that the ultimate control for these terraces is the availability of sediment on the hillslopes, with hillslope stripping supplying large sediment loads early in wet periods. At the Pisco river, this is manifest as an approximately 4-fold increase in erosion rates during pluvial periods. We suggest that this mechanism may also control terrace occurrence other semi-arid escarpment settings.

  20. Balanço hídrico em solo com cultivos de subsistência no semi-árido do nordeste do Brasil Water budget in a soil with food crops in the semi-arid region of northeast Brazil

    Directory of Open Access Journals (Sweden)

    Antonio Celso Dantas Antonino

    2000-04-01

    Full Text Available Tendo em vista ser a água limitante e haver poucos estudos sobre o balanço hídrico em cultivos do semi-árido nordestino, instalou-se um experimento em Coxixola, PB, com quatro tratamentos (plantios de milho e de feijão, solo nu e com cobertura morta, parcelas de 7,7 x 10 m e espaçamento de plantio de 1,1 x 1,0 m. Foram medidos chuva, evaporação (Tanque "classe A" e armazenamento de água no solo (sonda de nêutrons. A chuva pouca (212 mm e mal distribuída causou restrição hídrica na parte final do experimento e foi responsável pelas baixas eficiências de uso de água e baixas produtividades do milho (grãos e biomassa total, 282 e 1141 kg ha-1 e do feijão (166 e 558 kg ha-1. Solo nu e com cobertura morta tiveram comportamento semelhante, com grandes perdas de água (1,57 e 1,48 mm dia-1, respectivamente e apenas pequenos aumentos nas lâminas armazenadas no perfil do solo, ao final do experimento (28 e 35 mm, respectivamente. O pequeno aumento e a dificuldade de obtenção de resíduos vegetais fazem com que esta cobertura morta não seja prática promissora na região.Considering that water is a limiting factor and there are few studies on water balance in the semi-arid Northeastern Brazil, an experiment was established at Coxixola, PB, Brazil, with four treatments (corn and beans crops, bare soil and soil covered with mulch, in plots of 7.7 x 10 m and plant spacing of 1.1 x 1.0 m. Rainfall, evaporation (Class A tank and soil water (neutron probe were monitored. Low (212 mm and irregular rainfall resulted in water deficit towards the final period of the experiment and was responsible for the low water use efficiencies and low productivity of corn (grain and total biomass, 282 and 1141 kg ha-1 and beans (166 and 558 kg ha-1. Bare soil and mulch had similar results, with high water losses, 1.57 and 1.48 mm day-1, respectively, and only small increases in stored soil water (28 and 35 mm, respectively were observed at the end of

  1. Tradeoffs of modifications of storm water managements systems for nitrogen loss pathways in semi-arid ecosystems

    Science.gov (United States)

    Lohse, K. A.; Gallo, E. L.; Brooks, P. D.; Meixner, T.; McIntosh, J. C.

    2013-12-01

    Urbanization is altering hydrologic and nitrogen (N) inputs to streams that may substantially increase nitrogen-containing trace gas emissions to the atmosphere with regional and global consequences. In the semi-arid southwestern US, human modifications of ephemerally dry stream channels interact with hydrologic and nitrogen alterations to lead to extremely high fluxes of nitrous oxide (N2O). Cumulative N2O losses ranged from 0.04 to 0.97 mg N m-2 in 6 hr for rainfall compared to 22.5-59.3 mg N m-2 for flood pulse events. Impervious channels eliminated N trace gas losses but increased delivery of water and N to downstream ecosystems and areas of focused recharge by 6 fold compared to watersheds with greater pervious channel lengths. In contrast, importation of clay into channels increased total N trace gas losses by 8-32 fold relative to more natural sand dominated channels but this result depended on the degree of wetting. Our integrated findings suggest human modification of storm water management systems to impervious channels increases delivery of water and N to downstream navigable waters and areas of focused recharge whereas importation of clay materials leads to higher N trace gas losses and reduced delivery of nitrate. Management will need to address long-term challenges of balancing tradeoffs of greenhouse N gases and N in water supplies, intermediate scale issues of enhancing recharge, and short-term issues of removing water and preventing flooding.

  2. Fertilizer induced nitrous oxide emissions from Vertisols and Alfisols during sweet sorghum cultivation in the Indian semi-arid tropics.

    Science.gov (United States)

    Ramu, Karri; Watanabe, Takeshi; Uchino, Hiroshi; Sahrawat, Kanwar L; Wani, Suhas P; Ito, Osamu

    2012-11-01

    Nitrous oxide (N(2)O) emissions from Vertisols and Alfisols during sweet sorghum cultivation in the Indian semi-arid tropics were determined using a closed chamber technique during the rainy season (June-October) of 2010. The study included two treatments, nitrogen (N) at a rate of 90 kg/ha and a control without N fertilizer application. The N(2)O emissions strongly coincided with N fertilization and rainfall events. The cumulative N(2)O-N emission from Alfisols was 1.81 N(2)O-N kg/ha for 90 N treatment and 0.15 N(2)O-N kg/ha for the 0 N treatment. Similarly, the N(2)O-N emission from Vertisols was 0.70 N(2)O-N kg/ha for 90 N treatment and 0.09 N(2)O-N kg/ha for the 0 N treatment. The mean N(2)O-N emission factor for fertilizer induced emissions from the Alfisols was 0.90% as compared to 0.32% for Vertisols. Our results suggest that the N(2)O emissions are dependent on the soil properties. Therefore, the monitoring of N(2)O emissions from different agro-ecological regions, having different soil types, rainfall characteristics, cropping systems and crop management practices are necessary to develop comprehensive and accurate green house gas inventories.

  3. Vulnerability and policy relevance to drought in the semi-arid tropics of Asia – A retrospective analysis

    Directory of Open Access Journals (Sweden)

    Naveen P. Singh

    2014-06-01

    Full Text Available Of all the natural hazards, drought affects the maximum number of people globally causing devastating impacts. It is a reality that drought results in sets of socio-economic impacts starting with crop-yield failure, unemployment, erosion of assets, income decrease, poor nutrition and decreasing risk absorptive capacity, thereby increasing the vulnerability of the community. This paper gives a brief of the existing approaches that focus on vulnerability and impact assessment aid to characterize and identify regions, sectors and communities which are at risk for drought currently and in the future. It also discusses the limitation, constraints and pre-requisites in these approaches and highlights the importance of micro-level information to have a more realistic understanding of impact and vulnerability through illustration, with reference to the recent study conducted by the International Crops Research Institute for the Semi-Arid Tropics (ICRISAT. This exercise will provide a guiding framework for devising action plans to improve adaptive capacity among vulnerable populations.

  4. Influence of geochemical processes on hydrochemistry and irrigation suitability of groundwater in part of semi-arid Deccan Plateau, India

    Science.gov (United States)

    Vasu, Duraisamy; Singh, Surendra Kumar; Tiwary, Pramod; Sahu, Nisha; Ray, Sanjay Kumar; Butte, Pravin; Duraisami, Veppangadu Perumal

    2017-02-01

    Major ion geochemistry was used to characterise the chemical composition of groundwater in part of semi-arid Deccan plateau region to understand the geochemical evolution and to evaluate the groundwater quality for irrigation. The study area comprises peninsular gneissic complex of Archean age, younger granites and basaltic alluvium. Forty-nine georeferenced groundwater samples were collected and analysed for major ions. The ionic sequence based on relative proportions was Na+ > Mg2+ > Ca2+ > SO4 2- > HCO3 - > Cl- > CO3 2- > BO3 3- > K+. High Na+, Mg2+ and Ca2+ were generally associated with basaltic alluvial formation, whereas pH, electrical conductivity (EC) and total dissolved salts (TDS) were found to be higher in granitic formations. High standard deviation for EC, TDS, Na+, Ca2+ and Mg2+ indicated the dispersion of ionic concentration throughout the study area. Four major hydrochemical facies identified were Na-Mg-HCO3 type; Mg-Na-HCO3 type; Na-Mg-Ca-SO4 and Mg-Na-Ca-SO4 type. The graphical plots indicated that the groundwater chemistry was influenced by rock-water interaction, silicate weathering and reverse ion exchange. Sodium-dominated waters might have impeded the hydraulic properties of soils as a result of long-term irrigation.

  5. Safe greywater reuse to augment water supply and provide sanitation in semi-arid areas of rural India.

    Science.gov (United States)

    Godfrey, S; Labhasetwar, P; Wate, S; Jimenez, B

    2010-01-01

    Water reuse is recognized as a tool to increase water supply in peri-urban areas of semi-arid and arid regions of the world. However, it is an option rarely explored for rural areas in developing countries, and has not been documented extensively in the scientific literature. This paper presents results from 6 greywater reuse systems which were built with the objective to augment water supply and to provide sanitation in rural low income areas of Madhya Pradesh, India. The systems are based on reclaiming greywater from bathing for the use in toilet flushing and kitchen garden irrigation. The reuse systems were implemented based on the scientific rationale presented in the WHO (2006) guidelines. The paper presents evidence from the operation and evaluation of the greywater treatment plants under field conditions between 2005 and 2008. The paper concludes that greywater is a highly cost effective solution for water scarcity. In this study, reusing greywater resulted in a 60% increase in water availability, a reduction in open defecation and a fourfold increase in food availability.

  6. Where does blue water go in the semi-arid area of northern China under changing environments?

    Science.gov (United States)

    Ren, L.; Yuan, F.; Yong, B.; Jiang, S.; Yang, X.; Gong, L.; Ma, M.; Liu, Y.; Shen, H.

    2014-09-01

    River flow regimes in the semi-arid region of northern China show a decreasing trend in terms of quantity. River runoff (i.e. blue water) reduction within the Laohahe catchment, the source area of the Liaohe River basin, manifests the aridity that exists widely in northern China. According to the water balance equation, during the past half-century, observed streamflow records in the Laohahe catchment show that blue water was re-directed to green water flow (i.e. evapotranspiration) over annual and decadal time scales, whereas precipitation did not vary much. Human activities and land-use/land-cover changes are the fundamental reasons for such runoff change. In the studied catchment, extensive land reclamation for agriculture, water withdrawal from streams, and abstraction from aquifers for irrigation are the direct and main causes leading to the decrease in observed blue water. These factors further demonstrate that a land-use decision is also a decision about water. Therefore, there is a need for an integrated modelling framework to intrinsically link climate, hydrological, and agricultural models with social and economic analyses.

  7. Sr isotope study in the drainage water in semi-arid irrigation district, Adana, Turley

    Science.gov (United States)

    Kume, T.; Akca, E.; Nakano, T.; Nagano, T.; Kapur, S.; Watanabe, T.

    2009-12-01

    The management of drainage water from irrigated lands is an important issue not only for agricultural planning but also for environmental conservation. In arid and semi-arid regions, drainage water is reused as irrigation water due to lack of enough fresh irrigation water and irrigation schemes. The drainage water reuse should be undertaken only if long-term deleterious effects on soil properties can be avoided. In addition to salt concentration, the origin of salts of drainage water should be examined to avoid agricultural and environmental pollution. The Lower Seyhan Irrigation Project (LSIP), Adana, Turkey, faces to the Mediterranean. In the LSIP, intensive irrigated agriculture has conducted since 1960s. Recently, total amount of applied irrigation water has been increased along with expansion of agricultural area and fertilizer input is also increasing. Some part of the southern lowest fields is under sea level. Soil salinization and shallow groundwater have been observed in the lowest part due to irrigation water seepage from upper stream and insufficient drainage. Moreover, agricultural drainage water has been used for irrigation water there, so that the salt is a mixture of several components. Therefore, geo-chemical measurements are indispensable to clarify the source of salt. In this study, we focused on the isotopic and chemical compositions of agricultural drain water of three main drainage canals in the LSIP. Seasonal changes in drainage features were examined using 87Sr/86Sr ratio (Sr isotope ratio) and major cation data. The abundances of possible end components were determined using mixing model. The result of measurements showed that there was a good relationship between 87Sr/86Sr values and reciprocal values of Sr concentration, while drain water quality clearly differed between summer and winter. This means Sr of drain water consists of several origins. The relationship and other data showed that Sr of drain water was a mixture of three

  8. A 500-year history of floods in the semi arid basins of south-eastern Spain

    Science.gov (United States)

    Sánchez García, Carlos; Schulte, Lothar; Peña, Juan Carlos; Carvalho, Filpe; Brembilla, Carla

    2016-04-01

    Floods are one of the natural hazards with higher incidence in the south-eastern Spain, the driest region in Europe, causing fatalities, damage of infrastructure and economic losses. Flash-floods in semi arid environments are related to intensive rainfall which can last from few hours to days. These floods are violent and destructive because of their high discharges, sediment transport and aggradation processes in the flood plain. Also during historical times floods affected the population in the south-eastern Spain causing sever damage or in some cases the complete destruction of towns. Our studies focus on the flood reconstruction from historical sources of the Almanzora, Aguas and Antas river basins, which have a surface between 260-2600 km2. We have also compiled information from the Andarax river and compared the flood series with the Guadalentín and Segura basins from previous studies (Benito et. al., 2010 y Machado et al., 2011). Flood intensities have been classified in four levels according to the type of damage: 1) ordinary floods that only affect agriculture plots; 2) extraordinary floods which produce some damage to buildings and hydraulic infrastructure; 3) catastrophic floods which caused sever damage, fatalities and partial or complete destruction of towns. A higher damage intensity of +1 magnitude was assigned when the event is recorded from more than one major sub-basin (stretches and tributaries such as Huércal-Overa basin) or catchment (e.g. Antas River). In total 102 incidences of damages and 89 floods were reconstructed in the Almanzora (2.611 km2), Aguas (539 km2), Antas (261 km2) and Andarax (2.100 km2) catchments. The Almanzora River was affected by 36 floods (1550-2012). The highest events for the Almanzora River were in 1580, 1879, 1973 and 2012 producing many fatalities and destruction of several towns. In addition, we identified four flood-clusters 1750-1780, 1870-1900, 1960-1977 and 1989-2012 which coincides with the periods of

  9. Mapping Soil hydrologic features in a semi-arid irrigated area in Spain

    Science.gov (United States)

    Jiménez-Aguirre, M.° Teresa; Isidoro, Daniel; Usón, Asunción

    2016-04-01

    The lack of soil information is a managerial problem in irrigated areas in Spain. The Violada Irrigation District (VID; 5234 ha) is a gypsic, semi-arid region in the Middle Ebro River Basin, northeast Spain. VID is under irrigation since the 1940's. The implementation of the flood irrigation system gave rise to waterlogging problems, solved along the years with the installation of an artificial drainage network. Aggregated water balances have been performed in VID since the early 1980's considering average soil properties and aggregated irrigation data for the calculations (crop evapotranspiration, canal seepage, and soil drainage). In 2008-2009, 91% of the VID was modernized to sprinkler irrigation. This new system provides detailed irrigation management information that together with detailed soil information would allow for disaggregated water balances for a better understanding of the system. Our goal was to draw a semi-detailed soil map of VID presenting the main soil characteristics related to irrigation management. A second step of the work was to set up pedotransfer functions (PTF) to estimate the water content and saturated hydraulic conductivity (Ks) from easily measurable parameters. Thirty four pits were opened, described and sampled for chemical and physical properties. Thirty three additional auger holes were sampled for water holding capacity (WHC; down to 60 cm), helping to draw the soil units boundaries. And 15 Ks tests (inverse auger hole method) were made. The WHC was determined as the difference between the field capacity (FC) and wilting point (WP) measured in samples dried at 40°C during 5 days. The comparison with old values dried at 105°C for 2 days highlighted the importance of the method when gypsum is present in order to avoid water removal from gypsum molecules. The soil map was drawn down to family level. Thirteen soil units were defined by the combination of five subgroups [Typic Calcixerept (A), Petrocalcic Calcixerept (B), Gypsic

  10. 半干旱区气候变化背景下近20年内蒙古武川县耕地质量变化%Cultivated land quality change of Wuchuan county in Inner Mongolia under background of climate change in semi-arid regions during recent 20 years

    Institute of Scientific and Technical Information of China (English)

    王立为; 安萍莉; 潘志华; 赫迪; 董智强

    2013-01-01

    Cultivated land quality is a key factor of national economic and social sustainable development. The change of cultivated land quality with climate change has become one of the hot research areas in global change in recent years. Based on the meteorological data, soil information and field experimental data were used, utilizing the Wageninngen method recommended by the Food and Agriculture Organization (FAO) to calculate the potential productivity of potato and spring wheat from 1989 to 2009 in Wuchuan County, Inner Mongolia, a typical semi-arid climate-sensitive area in North China. We examined the influence of climate change on production potential, the standard cropping system, and the yield. Further, by the method of regulations of Farmland classification, we used the data of potential productivity and land use to analyze the changes of natural quality grades and utilization grades under climate change. The results showed that:(1) The annual temperature of Wuchuan County increased at an average rate of 0.57℃/10a during 1967-2009. The precipitation varied greatly among the years, and the annual precipitation declined slightly over time. The soil relative humidity in soil layers 0-10 cm and 10-20 cm depth in crop growing season (April-September) in the period 1989-2009 had a decreasing trend with an average rate of 1.8%/a and 1.5%/a, respectively. Drought index increased noticeably. In conclusion, Wuchuan County was getting warmer and dryer under climate change. (2) Most of the cultivated lands were the dry lands in Wuchuan county (accounting for more than 90%), but the irrigated lands increased in recent years. The main crop in Wuchuan county was potatoes in 2009 instead of spring wheat in 1989. The planting area of potatoes increased from 8.4%to 39.8%, while spring wheat planting area decreasing from 52.1%to 17.1%in the period 1989-2009. (3) The production potential of the potatoes and spring wheat showed a declining trend under the dry warming climate in

  11. Burning crop residues under no-till in semi-arid land, Northern Spain - effects on soil organic matter, aggregation, and earthwor populations.

    NARCIS (Netherlands)

    Virto, I.; Imaz, M.J.; Enrique, A.; Hoogmoed, W.B.; Bescansa, P.

    2007-01-01

    Stubble burning has traditionally been used in semi-arid land for pest and weed control, and to remove the excess of crop residues before seeding in no-tillage systems. We compared differences in soil properties in a long-term (10 years) tillage trial on a carbonated soil in semi-arid north-east Spa

  12. Simultaneous assimilation of satellite and eddy covariance data for improving terrestrial water and carbon simulations at a semi-arid woodland site in Botswana

    NARCIS (Netherlands)

    Kato, T.; Knorr, W.; Scholtze, M.; Veenendaal, E.M.; Kaminski, T.; Kattge, J.; Gobron, N.

    2013-01-01

    Terrestrial productivity in semi-arid woodlands is strongly susceptible to changes in precipitation, and semi-arid woodlands constitute an important element of the global water and carbon cycles. Here, we use the Carbon Cycle Data Assimilation System (CCDAS) to investigate the key parameters control

  13. Species screening and biomass trials of woody plants in the semi-arid Southwest United States

    Energy Technology Data Exchange (ETDEWEB)

    Kirmse, R.D.; Fisher, J.T.

    1989-01-01

    Species screening and selection trials are being conducted to identify appropriate woody species and technology for biofuel farming in the southwest United States. During the initial phase of the program, 26 native and exotic species have been tested at sites in Texas, New Mexico and Arizona. Second season biomass estimates indicate that initial yields of 3.2-8.5 dry Mg ha/sup -1/ year/sup -1/ are possible without post-establishment irrigation. The species Atriplex canescens (Pursh) Nutt., Prosopis alba Griseb. and Leucaena leucocephala (Lam.) de Wit reached canopy closure within two seasons of growth and are identified as rapid initial biomass producers under the semi-arid conditions of the study area. (author).

  14. Dependence of juvenile reef fishes on semi-arid hypersaline estuary microhabitats as nurseries.

    Science.gov (United States)

    Sales, N S; Dias, T L P; Baeta, A; Pessanha, A L M

    2016-07-01

    The differences between fish assemblages in three microhabitat types, in relation to vegetation and sediment characteristics of a hypersaline estuary located in an semi-arid zone in north-eastern Brazil, were investigated. Fishes were collected using a beach seine during the rainy and dry seasons in 2012. A total of 78 species were recorded, with the most common families being Gerreidae, Lutjanidae and Tetraodontidae. The majority of species were represented by juveniles, with Eucinostomus argenteus, Ulaema lefroyi and Sphoeroides greeleyi being the dominant species. The fish assemblage structures differed significantly among microhabitat types, with the narrow intertidal flat adjacent to the mangrove fringe supporting the most diverse fish fauna. In addition, only 27 species were common to all of the microhabitats. The results support the hypothesis that hypersaline estuaries serve as important nursery areas for various reef fish species, due to the structural complexity provided by their macroalgae beds and mangroves.

  15. IMPACT OF ZOOTECHNICAL PARAMETERS ON CELL QUALITY OF CATTLE MILK (SEMI-ARID COSTAL TUNISIA

    Directory of Open Access Journals (Sweden)

    R. HAJ MBAREK

    2015-09-01

    Full Text Available The work was realized on a sample of 50 cattle herds, conducted in aboveground, in a coastal area of the semi-arid Tunisia, by using investigation related to cows and their breeding and milking conditions as well as despoliation in milk control data. Analysis of the data relating to the parameters of udder conformation and cow cleanliness revealed that “Udder depth” settings “Udder cleanliness” have been shown to affect the ICC and are considered factors risk of bovine mastitis. The study of breeding and milking conditions highlight some significant factors on changes on the variation of cell counts and the probability of the spread of mastitis, especially the "No disinfection of teat." The level of housing, the analysis revealed that the use of a litter reduced to half the average of ICC which proved highly related to the cleanliness of both the sleeping area as the udder.

  16. Organic textile waste as a resource for sustainable agriculture in arid and semi-arid areas.

    Science.gov (United States)

    Eriksson, Bo G

    2017-03-01

    New vegetation in barren areas offers possibilities for sequestering carbon in the soil. Arid and semi-arid areas (ASAs) are candidates for new vegetation. The possibility of agriculture in ASAs is reviewed, revealing the potential for cultivation by covering the surface with a layer of organic fibres. This layer collects more water from humidity in the air than does the uncovered mineral surface, and creates a humid environment that promotes microbial life. One possibility is to use large amounts of organic fibres for soil enhancement in ASAs. In the context of the European Commission Waste Framework Directive, the possibility of using textile waste from Sweden is explored. The costs for using Swedish textile waste are high, but possible gains are the sale of agricultural products and increased land prices as well as environmental mitigation. The findings suggest that field research on such agriculture in ASAs should start as soon as possible.

  17. Demographic noise and resilience in a semi-arid ecosystem model

    CERN Document Server

    Realpe-Gomez, John; Galla, Tobias; McKane, Alan J; Rietkerk, Max

    2013-01-01

    The scarcity of water characterizing drylands forces vegetation to adopt appropriate survival strategies. Some of these generate water-vegetation feedback mechanisms that can lead to spatial self-organisation of vegetation. To date these phenomena have mostly been studied with models representing plants by a density of biomass, varying continuously in time and space. Such models disregard the discrete nature of plant individuals and their intrinsically stochastic behaviour. These features give rise to demographic noise, which can influence the qualitative dynamics of ecosystem models. In the present work we explore the effects of demographic noise on the resilience of a model semi-arid ecosystem. We introduce a spatial stochastic eco-hydrological hybrid model in which plants are modelled as discrete entities subject to stochastic dynamical rules, while the dynamics of surface and soil water are described by continuous variables. The model has a deterministic approximation very similar to previous continuous m...

  18. The causes of stemflow variation in three semi-arid growing species of northeastern Mexico

    Science.gov (United States)

    Návar, José

    1993-05-01

    This study was conducted to determine the role of some plant parameters on stemflow generation. Stemflow measurements in individual shrubs of three semi-arid growing species ( Diospyrus texana, Acacia farnesiana and Prosopis laevigata) were carried out under natural and simulated rainfall conditions in northeastern Mexico. Stemflow coefficients for individual shrubs were developed. The analysis of variance showed a significant difference among the species for both natural and simulated rainfall conditions. The multiple linear models suggested that the number of branches and position on the canopy, instead of total projected branch area, controls stemflow. There were also suggestions that bark roughness, leaf and twig position may also explain some of the interspecific stemflow variation. This contribution was suggested by an introduced funnelling ratio.

  19. Spatiotemporal soil and saprolite moisture dynamics across a semi-arid woody plant gradient

    Science.gov (United States)

    Niemeyer, Ryan J.; Heinse, Robert; Link, Timothy E.; Seyfried, Mark S.; Klos, P. Zion; Williams, Christopher J.; Nielson, Travis

    2017-01-01

    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-dominated western juniper stand we compared moisture dynamics horizontally across a discontinuous canopy, and vertically in soil and saprolite. We monitored soil moisture at 15 and 60 cm and conducted periodic electromagnetic induction and electrical resistivity tomography surveys aimed at sensing moisture changes within the root zone and saprolite. Timing of soil moisture dry down at 15 cm was very similar between canopy patches and interspace. Conversely, dry down at 60 cm occurred 22 days earlier in the interspace than under canopy patches. After rainfall, interspaces with more shrubs showed greater increases in soil moisture than interspaces with few shrubs. For the few rainfall events that were large enough to increase soil moisture at 60 cm, increases in moisture occurred almost exclusively below the canopy. Soil water holding capacity from 0 to 150 cm was a primary driver of areas that were associated with the greatest change in distributed electrical conductivity - an indicator of changes in soil moisture - across the growing season. Vegetation was also correlated with a greater seasonal change in electrical conductivity at these depths. The seasonal change in resistivity suggested moisture extraction by juniper well into the saprolite, as deep as 12 m below the surface. This change in deep subsurface resistivity primarily occurred below medium and large juniper trees. This study suggests how tree roots are both increasing infiltration below their canopy while also extracting moisture at depths of upwards of 12 m. Information from this study can help improve our understanding of juniper resilience to drought and the hydrologic impacts of semi-arid land cover

  20. Potential of green infrastructure to restore predevelopment water budget of a semi-arid urban catchment

    Science.gov (United States)

    Feng, Youcan; Burian, Steven; Pomeroy, Christine

    2016-11-01

    This paper presents a study of the potential for green infrastructure (GI) to restore the predevelopment hydrologic cycle in a semi-arid urban catchment. Simulations of stormwater runoff from a 0.11-km2 urban catchment in Salt Lake City, Utah, USA for predeveloped (Natural Hydrology, NH), developed (Baseline, BL), and developed with GI (Green Infrastructure, GI) conditions were executed for a one-year period. The study was repeated for a relatively dry year, wet year, and an average year based on precipitation amounts in the year. Bioretention and green roofs were chosen for the GI plan. Results showed that the water budget of the catchment with the GI plan implemented more closely matches the NH water budget compared to the BL scenario, for all three years (dry, wet, average). The BL and GI scenarios showed more significant modifications to the water budget than what has been found by studies in humid climates. Compared to the BL condition, GI annually reduces surface runoff by 35%, 45%, and 43% and restores evapotranspiration by 18%, 19%, and 25% for the dry, average, wet years, respectively. Based on the introduced water budget restoration coefficient (WBRC), the water budget of the study catchment was restored by the GI plan to 90%, 90%, and 82% of the predevelopment state in the dry, average, and wet years, respectively. By comparing the WBRC estimated for other studies, it is further inferred that the water budget is more significantly affected by development and GI restoration in semi-arid than humid climates, but the differences lessen as the precipitation amount increases.

  1. Infrequent composted biosolids applications affect semi-arid grassland soils and vegetation.

    Science.gov (United States)

    Ippolito, J A; Barbarick, K A; Paschke, M W; Brobst, R B

    2010-05-01

    Monitoring of repeated composted biosolids applications is necessary for improving beneficial reuse program management strategies, because materials will likely be reapplied to the same site at a future point in time. A field trial evaluated a single and a repeated composted biosolids application in terms of long-term (13-14 years) and short-term (2-3 years) effects, respectively, on soil chemistry and plant community in a Colorado semi-arid grassland. Six composted biosolids rates (0, 2.5, 5, 10, 21, 30 Mg ha(-1)) were surface applied in a split-plot design study with treatment (increasing compost rates) as the main factor and co-application time (1991, or 1991 and 2002) as the split factor applications. Short- and long-term treatment effects were evident in 2004 and 2005 for soil 0-8 cm depth pH, EC, NO(3)-N, NH(4)-N, total N, and AB-DTPA soil Cd, Cu, Mo, Zn, P, and Ba. Soil organic matter increases were still evident 13 and 14 years following composted biosolids application. The repeated composted biosolids application increased soil NO(3)-N and NH(4)-N and decreased AB-DTPA extractable Ba as compared to the single composted biosolids application in 2004; differences between short- and long-term applications were less evident in 2005. Increasing biosolids rates resulted in increased native perennial grass cover in 2005. Plant tissue Cu, Mo, Zn, and P concentrations increased, while Ba content decreased depending on specific plant species and year. Overall, the lack of many significant negative effects suggests that short- or long-term composted biosolids application at the rates studied did not adversely affect this semi-arid grassland ecosystem.

  2. The importance of plant water use on evapotranspiration covers in semi-arid Australia

    Directory of Open Access Journals (Sweden)

    A. Schneider

    2012-10-01

    Full Text Available We estimated the evapotranspiration (ET for an area vegetated with characteristic semi-arid native Australian plant species on ET mine waste cover systems. These systems aim to minimise drainage into underlying hazardous wastes by maximising evaporation (E from the soil surface and transpiration from vegetation. An open top chamber was used to measure diurnal and daily ET of two plant species – Senna artemisioides (silver cassia and Sclerolaena birchii (galvanised burr – after a simulated rainfall event, as well as E from bare soil. Both ET and E decreased with increasing time after initial watering. Different temporal patterns were observed for daily ET from the two plant species and E from bare soil, revealing Senna artemisioides as intensive and Sclerolaena birchii as extensive water exploiters. A strong positive linear relationship was identified between ET (and E, and the atmospheric water demand represented by the vapour pressure deficit. The relationship always was more pronounced in the morning than in the afternoon, indicating a diminishing water supply from the soil associated with a declining unsaturated hydraulic conductivity of the soil in the afternoon. The slopes of the regression lines were steepest for Senna artemisioides, reflecting its intensive water-exploiting characteristics. We used the derived estimates of ET and E to predict the effect of species composition on plot ET in relation to total vegetation coverage. Although both species proved suitable for an operational ET cover system, vegetation coverage should exceed at least 50% in order to markedly influence plot ET, a value which is likely to be unsustainable in semi-arid climates.

  3. Contribution of semi-arid ecosystems to interannual variability of the global carbon cycle.

    Science.gov (United States)

    Poulter, Benjamin; Frank, David; Ciais, Philippe; Myneni, Ranga B; Andela, Niels; Bi, Jian; Broquet, Gregoire; Canadell, Josep G; Chevallier, Frederic; Liu, Yi Y; Running, Steven W; Sitch, Stephen; van der Werf, Guido R

    2014-05-29

    The land and ocean act as a sink for fossil-fuel emissions, thereby slowing the rise of atmospheric carbon dioxide concentrations. Although the uptake of carbon by oceanic and terrestrial processes has kept pace with accelerating carbon dioxide emissions until now, atmospheric carbon dioxide concentrations exhibit a large variability on interannual timescales, considered to be driven primarily by terrestrial ecosystem processes dominated by tropical rainforests. We use a terrestrial biogeochemical model, atmospheric carbon dioxide inversion and global carbon budget accounting methods to investigate the evolution of the terrestrial carbon sink over the past 30 years, with a focus on the underlying mechanisms responsible for the exceptionally large land carbon sink reported in 2011 (ref. 2). Here we show that our three terrestrial carbon sink estimates are in good agreement and support the finding of a 2011 record land carbon sink. Surprisingly, we find that the global carbon sink anomaly was driven by growth of semi-arid vegetation in the Southern Hemisphere, with almost 60 per cent of carbon uptake attributed to Australian ecosystems, where prevalent La Niña conditions caused up to six consecutive seasons of increased precipitation. In addition, since 1981, a six per cent expansion of vegetation cover over Australia was associated with a fourfold increase in the sensitivity of continental net carbon uptake to precipitation. Our findings suggest that the higher turnover rates of carbon pools in semi-arid biomes are an increasingly important driver of global carbon cycle inter-annual variability and that tropical rainforests may become less relevant drivers in the future. More research is needed to identify to what extent the carbon stocks accumulated during wet years are vulnerable to rapid decomposition or loss through fire in subsequent years.

  4. The importance of plant water use on evapotranspiration covers in semi-arid Australia

    Science.gov (United States)

    Schneider, A.; Arnold, S.; Doley, D.; Mulligan, D. R.; Baumgartl, T.

    2012-10-01

    We estimated the evapotranspiration (ET) for an area vegetated with characteristic semi-arid native Australian plant species on ET mine waste cover systems. These systems aim to minimise drainage into underlying hazardous wastes by maximising evaporation (E) from the soil surface and transpiration from vegetation. An open top chamber was used to measure diurnal and daily ET of two plant species - Senna artemisioides (silver cassia) and Sclerolaena birchii (galvanised burr) - after a simulated rainfall event, as well as E from bare soil. Both ET and E decreased with increasing time after initial watering. Different temporal patterns were observed for daily ET from the two plant species and E from bare soil, revealing Senna artemisioides as intensive and Sclerolaena birchii as extensive water exploiters. A strong positive linear relationship was identified between ET (and E), and the atmospheric water demand represented by the vapour pressure deficit. The relationship always was more pronounced in the morning than in the afternoon, indicating a diminishing water supply from the soil associated with a declining unsaturated hydraulic conductivity of the soil in the afternoon. The slopes of the regression lines were steepest for Senna artemisioides, reflecting its intensive water-exploiting characteristics. We used the derived estimates of ET and E to predict the effect of species composition on plot ET in relation to total vegetation coverage. Although both species proved suitable for an operational ET cover system, vegetation coverage should exceed at least 50% in order to markedly influence plot ET, a value which is likely to be unsustainable in semi-arid climates.

  5. Strategies to reducing GHG emissions in semi-arid rangelands of Mexico

    Directory of Open Access Journals (Sweden)

    Heriberto Díaz Solís

    2016-03-01

    Full Text Available SESS (Simple Ecological Sustainability Simulator model was modified to evaluate 3 management strategies that could increase CO2 sequestration and reduce methane emissions in cow-calf production systems in semi-arid rangelands. The management strategies included (1 maintenance of a high and constant stocking rate (CONTROL, which is the most common current practice, (2 maintenance of a low and constant stocking rate (LOW SR and (3 adjustment of stocking rate before the beginning of each breeding season based on the amount of precipitation during the previous growing season (REPLA-PPT. The model was parameterized to represent a typical extensive (5 000 ha cow-calf production system in the northeastern portion of the Mexican state of Coahuila under an historical (1950 to 1994 precipitation regime, and compared carbon sequestration, methane emissions, animal performance and net profit resulting from each strategy. Results of the 45-year simulations indicated the REPLA-PPT stocking rate strategy had the greatest improvement of range condition, captured more CO2 in vegetation, had the lowest methane emissions, substantially improved mean body condition score and reduced annual mortality of cattle, compared to the constant stocking rate strategies. REPLA-PPT also showed the highest values for calves weaned, and kg weaned per ton of methane produced and highest long-term net profit. This suggests that adaptive management of extensive cow-calf production systems in semi-arid environments could increase carbon sequestration in soils and reduce methane emissions, while improving range production, maintaining animal production and giving the greatest long-term net profit.

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

    Directory of Open Access Journals (Sweden)

    Miriam K. Joshua

    2016-03-01

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

  7. Soil tillage and water infiltration in semi-arid Morocco: the role fo surface and sub-surface soil conditions

    NARCIS (Netherlands)

    Dimanche, P.H.; Hoogmoed, W.B.

    2002-01-01

    Production of cereals in a dryland farming system forms an important part of agricultural production in Morocco. Yield levels on the Saïs Plateau between Meknès and Fez in the semi-arid zone, however, remain low possibly because of sub-optimum water use due to inefficient tillage systems. A study wa

  8. Water-scarcity patterns : spatiotemporal interdependencies between water use and water availability in a semi-arid river basin

    NARCIS (Netherlands)

    Oel, van Pieter Richard

    2009-01-01

    This thesis addresses the interdependencies between water use and water availability and describes a model that has been developed to improve understanding of the processes that drive changes and variations in the spatial and temporal distribution of water resources in a semi-arid river basin. These

  9. Off-farm income, risk, and agricultural production: a case study of smallholders in India's semi-arid tropics

    NARCIS (Netherlands)

    Berg, van den M.M.

    2001-01-01

    The purpose of the current study was to determine to what extent development of the nonfarm sector stimulates crop production and agricultural employment in India's semi-arid tropics (SAT). Two characteristics of India's SAT agriculture formed the basis for the study: i) that the major agricultural

  10. Building bridges using livestock as ecosystem engineers in semi-arid rangelands: Addressing conservation and livestock production goals

    Science.gov (United States)

    Domestic livestock have the potential to function as ecosystem engineers in semi-arid rangelands, but their utility has been compromised by management practices that emphasize livestock production, homogeneous use of vegetation and removal/control of interacting disturbances of fire and prairie dogs...

  11. The Role of Moisture in the Successful Rehabilitation of Denuded Patches of a Semi-Arid Environment in Kenya

    NARCIS (Netherlands)

    Mganga, K.Z.; Musimba, N.; Nyangito, M.M.; Musimba, N.K.R.; Mwangombe, A.W.; Ekaya, W.N.; Muiri, W.M.; Clavel, D.; Francis, J.; Kaufman, Von R.; Verhagen, A.

    2011-01-01

    This study investigated the role of moisture in the successful rehabilitation of denuded patches in semi-arid lands of Kenya and the primary productivity of three perennial rangelands grasses namely Cenchrus ciliaris (African foxtail), Enteropogon macrostachyus (Bush rye) and Eragrostis superba (Maa

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

    NARCIS (Netherlands)

    Huibers, F.P.

    1985-01-01

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

  13. Adaptive livelihood strategies employed by farmers to close the food gap in semi-arid south eastern Zimbabwe

    NARCIS (Netherlands)

    Murungweni, C.; Wijk, van M.T.; Giller, K.E.; Andersson, J.A.; Smaling, E.M.A.

    2014-01-01

    Rural households in semi-arid areas of southern Africa are confronted with numerous hazards that threaten the household food base. The new wildlife policy of establishing transfrontier conservation areas aims to increase conservation of wildlife resources while improving local livelihoods. This poli

  14. Evaluation of soil and water conservation measures in a semi-arid river basin in Tunisia using SWAT

    Science.gov (United States)

    The Merguellil catchment (Central Tunisia) is a typical Mediterranean semi-arid basin which suffers from regular water shortage aggravated by current droughts. During the recent decades the continuous construction of small and large dams and Soil and Water Conservation Works (i.e. Contour ridges) ha...

  15. Effects of feral free-roaming horses on semi-arid rangeland ecosystems: an example from the sagebrush steppe

    Science.gov (United States)

    Feral horses (Equus caballus) are viewed as a symbol of freedom and power; however, they are also a largely unmanaged, non-native grazer in North America, South America, and Australia. Information on their influence on vegetation and soil characteristics in semi-arid rangelands has been limited by ...

  16. Simply obtained global radiation, soil temperature and soil moisture in an alley cropping system in semi-arid Kenya

    NARCIS (Netherlands)

    Mungai, D.N.; Stigter, C.J.; Coulson, C.L.; Ng'ang'a, J.K.

    2000-01-01

    Global radiation, soil temperature and soil moisture data were obtained from a 4-6 year old Cassia siamea/maize (CM) alley cropping (or hedgerow intercropping) system, at a semi-arid site at Machakos, Kenya, in the late eighties. With the growing need to explore and manage variations in agro-ecosyst

  17. 'If only it would rain': Farmers' perceptions of rainfall and drought in semi-arid central Tanzania

    NARCIS (Netherlands)

    Slegers, M.F.W.

    2008-01-01

    Farmers in semi-arid East Africa prioritize drought as their major productivity-reducing problem, while scientists identify soil degradation as a major threat. The question that needs to be addressed is how farmers perceive drought. Insight into farmers¿ perceptions of drought could be the missing l

  18. Development and implementation of a monitoring and information system to increase water use efficiency in arid and semi-arid areas in Limarí, Central Chile (WEIN)

    Science.gov (United States)

    Berger, Erich; Balmert, David; Richter, Jürgen

    2016-10-01

    The project WEIN was funded by the Federal Ministry of Education and Research (BMBF | Berlin, Germany) in the framework of the high-tech strategy of Germany's program "KMU-Innovativ". The project started in 2012 and was completed in 2014. In the scope of the project, an integrated system for analysis, monitoring and information at river basin level was developed, which provides relevant information for all stakeholders that are concerned with water resource issues. The main objective of the project was to improve water use efficiency and hence ensure the agricultural production in the region. The pilot region, in which this system was implemented, is the semi-arid Limarí basin in Northern Central Chile. One of the main parts of the project was the development and implementation of a web- and app-based irrigation water ordering and accounting system for local farmers.

  19. Integrated approach to ecohydrology of semi-arid sites in areas of complex topography and biome transitions

    Science.gov (United States)

    Gutierrez, H. A.; Ivanov, V. Y.; Vivoni, E. R.; Bras, R. L.

    2005-05-01

    atmospheric forcing and the effects on the hydrologic fluxes, including changes in the water and energy balance. Finally, we point to further potential advances in the coupled simulation of the biosphere, atmosphere, and hydrosphere in semi-arid regions.

  20. Using remote-sensing technologies in combination with Cesium-137 measurements to estimate soil-erosion quantity in semi-arid steppe areas

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    Soil erosion by wind is one of the most important processes in the changing the earth’s surface in semi-arid areas,Thus it is of great importance to study soil-erosion action.Using integrated technologies of remote sensing and geochemistry radioactivity iso-tope to extract regional soil-erosion information and to calculate quantity of soil erosion is accomplished successfully in this paper by means of beneficial experiments in the Talatan region of the Gonghe Basin,which is located in northeastern Qinghai-Tibet Pla-teau in China.The results show that the soil erosion by wind is not intensive in this region;the erosion types belong to the classes of very-soft erosion and soft-erosion type,which account for 47.12 percent and 35.58 percent,respectively,of the total study area.In total,two kinds of soil erosion account for 82.70 percent of the study area;only a small area belongs to the classes of severe erosion and very-severe erosion;this area is about 22.14 km2.Severe deposition activity has taken place in this region,and has appeared in a large area(322.67 km2),which accounts for 11.78 percent of the total study area.The results of this study show that soil erosion and deposition inventories are 870,000-1,150,000 tons and 550,000-780,000 tons,respectively,per year.The soil in-ventory shows about 320,000-370,000 tons from Talatan to Longyangxia reservoir per year.Using remote-sensing technology and 137Cs techniques is a valid means to analyze and to evaluate the quantity of soil erosion by wind in semi-arid environments.

  1. Using remote-sensing technologies in combination with Cesium-137 measurements to estimate soil-erosion quantity in semi-arid steppe areas

    Institute of Scientific and Technical Information of China (English)

    ZhanJiang Sha; HaiZhou Ma; LingQin Li; Jinzhou Du; FeiQuan Wu; QiShun Fan

    2009-01-01

    Soil erosion by wind is one of the most important processes in the changing the earth's surface in semi-arid areas, Thus it is of great importance to study soil-erosion action. Using integrated technologies of remote sensing and geochemistry radioactivity isotope to extract regional soil-erosion information and to calculate quantity of soil erosion is accomplished successfully in this paper by means of beneficial experiments in the Talatan region of the Gonghe Basin, which is located in northeastern Qinghai-Tibet Plateau in China. The results show that the soil erosion by wind is not intensive in this region; the erosion types belong to the classes of very-soft erosion and soft-erosion type, which account for 47.12 percent and 35.58 percent, respectively, of the total study area.In total, two kinds of soil erosion account for 82.70 percent of the study area; only a small area belongs to the classes of severe erosion and very-severe erosion; this area is about 22.14 km2. Severe deposition activity has taken place in this region, and has appeared in a large area (322.67 km2), which accounts for 11.78 percent of the total study area. The results of this study show that soil erosion and deposition inventories are 870,000-1,150,000 tons and 550,000-780,000 tons, respectively, per year. The soil inventory shows about 320,000-370,000 tons from Talatan to Longyangxia reservoir per year. Using remote-sensing technology and 137Cs techniques is a valid means to analyze and to evaluate the quantity of soil erosion by wind in semi-arid environments.

  2. Entomological studies for surveillance and prevention of dengue in arid and semi-arid districts of Rajasthan, India

    Directory of Open Access Journals (Sweden)

    Anil Purohit

    2008-05-01

    Full Text Available Background & objectives: Rajasthan is one of the dengue endemic states of India. Very few studies have been published on entomological aspects of dengue in this state. Owing to water scarcity, inhabitants in desert areas overstore domestic water which leads to the persistence of dengue vectors within the domestic premises. Area specific knowledge on breeding, key containers and seasonal rhythms of vector population is essential for preparing an effective prevention plan against dengue. Present paper reports results of entomological investigations on dengue vectors in arid and semi-arid districts of Rajasthan. Methods: Longitudinal studies were undertaken during 2004–06 in one arid and two semi-arid dengue endemic districts of Rajasthan. Adult and larval Aedes were collected from the randomly selected houses in representative towns and villages with associated details of container types and water storage practices of inhabitants. Results: In urban areas during all the seasons adult house index (AHI of Aedes aegypti was maximum in desert zone (25 and least in semi-arid area with saline river III (1. The difference of AHI during three seasons was statistically significant (c2 = 16.1, p <0.01 for urban; and c2 = 50.71, p < 0.001 for rural. Breeding of Ae. aegypti among urban settings was maximum in desert zone. During all the seasons cement tanks were the key breeding habitats for Ae. aegypti in desert as well as semi-arid areas. Interpretation & conclusion: Water storage habits during summer season emerged to be the risk factor of vector abundance in urban areas of arid and semi-arid settings. A carefully designed study of key containers targeting cement tanks as the primary habitats of mosquito control may lead to commendable results for dengue prevention.

  3. Small-Scale Spatial Variability of Soil Nutrients and Vegetation Properties in Semi-Arid Northern China

    Institute of Scientific and Technical Information of China (English)

    CHEN Fu-Sheng; ZENG De-Hui; HE Xing-Yuan

    2006-01-01

    A field experiment was conducted at Kezuohouqi County, Inner Mongolia Autonomous Region of China, which was located on the southeastern edge of the Horqin Sandy Land, to study the spatial variability of soil nutrients for a smallscale, nutrient-poor, sandy site in a semi-arid region of northern China; to investigate whether or not there were "islands of fertility" at the experimental site; and to determine the key nutrient elements that sustained ecosystem stability. Results obtained from geostatistical analysis indicated that the spatial distribution pattern of soil total nitrogen (STN) was far different from those of soil organic matter (SOM), total phosphorus (STP), and total potassium (STK). Compared to SOM, STP, and STK, STN had a lower structural heterogeneity ratio and a longer range, while other elements were all similar. In addition, STN had an isotropic spatial structure, whereas the others had an anisotropic spatial structure.The spatial structure patterns of herbage species, cover, and height also differed, indicating that spatial variability was subjected to different ecological factors. Differences in the spatial variability patterns among soil nutrients and vegetation properties showed that soil nutrients for a small-scale were not the primary limiting factors that influenced herbage spatial distribution patterns. Incorporating spatial distribution patterns of tree species, namely, Pinus sylvestris var. mongolica Litv. and shrub Lespedeza bicolor Turcz. in a research plot and using fractal dimension, SOM, STP, and STK were shown to contribute to the "islands of fertility" phenomenon, however STN was not, possibly meaning that nitrogen was a key limiting element. Therefore, during restoration of similar ecosystems more attention should be given to soil nitrogen.

  4. Do protected areas networks ensure the supply of ecosystem services? Spatial patterns of two nature reserve systems in semi-arid Spain

    DEFF Research Database (Denmark)

    Castro, Antonio J.; Martín-López, Berta; López, Enrique;

    2015-01-01

    Protected areas are essential for conserving biodiversity, and these lands have traditionally been set aside for this purpose alone. However, the increasing global demand for agricultural and forestry commodities creates conflict and tradeoffs between dedicating land for conservation versus food...... that protected areas provide social and economic benefits that can be used to build political support and raise funds for conservation. We analyzed the capability of current protected area networks in the semi-arid region of Spain to provide intermediate regulating services (habitat preservation for threatened...... and groundwater recharge. Our results demonstrate that the integration of systematic analyses of ecosystem services gaps in protected area planning could contribute substantially to safeguarding ecosystem services and biodiversity jointly. However, our study also reveals substantial differences in intermediate...

  5. Detection of extreme climate events in semi-arid biomes using a combination of near-field and satellite based remote sensing across the New Mexico Elevation Gradient network of flux towers

    Science.gov (United States)

    Litvak, M. E.; Krofcheck, D. J.; Maurer, G.

    2015-12-01

    Semi-arid biomes in the Southwestern U.S. over the past decade have experienced high inter- and intra-annual variability in precipitation and vapor-pressure deficit (VPD), and from recent observations, are particularly vulnerable to both VPD and drought. Given the large land area occupied by semi-arid biomes in the U.S., the ability to quantify how climate extremes alter ecosystem function, in addition to being able to use satellites to remotely detect when these climate extremes occur, is crucial to scale the impact of these events on regional carbon dynamics. In an effort to understand how well commonly employed remote sensing platforms capture the impact of extreme events on semi-arid biomes, we coupled a 9-year record of eddy-covariance measurements made across an elevation/aridity gradient in NM with remote sensing data sets from tower-based phenocams, MODIS and Landsat 7 ETM+. We compared anomalies in air temperature, vapor pressure deficit, and precipitation, to the degree in variability of remote sensing vegetation indices (e.g, NDVI, EVI, 2G-Rbi, LST, etc.), and tower-derived gross primary productivity (GPP), across a range of temporal lags to quantify : 1) how sensitive vegetation indices from various platforms, LST, and carbon uptake are to climate disturbances, and the extremity of the disturbance; 2) how well correlated vegetation indices and tower fluxes are on monthly, seasonal and annual time scales, and if the degree to which they are correlated is related to the extent of climate anomalies during that period; and 3) the lags in the response of both GPP and vegetation indices to climate-anomalies and how well correlated these were on various time scales. Our initial results show differential sensitivities across a range of semi-arid ecosystems to drought and vapor pressure deficit. We see the strongest sensitivity of vegetation indices, and correlations between vegetation indices and tower GPP in the low and high elevation biomes that have a more

  6. Using ISBA model for partitioning evapotranspiration into soil evaporation and plant transpiration of irrigated crops under semi-arid climate

    Science.gov (United States)

    Aouade, Ghizlane; Jarlan, Lionel; Ezzahar, Jamal; Er-raki, Salah; Napoly, Adrien; Benkaddour, Abdelfettah; Khabba, Said; Boulet, Gilles; Chehbouni, Abdelghani; Boone, Aaron

    2016-04-01

    The Haouz region, typical of southern Mediterranean basins, is characterized by a semi-arid climate, with average annual rainfall of 250, whilst evaporative demand is about 1600 mm per year. Under these conditions, crop irrigation is inevitable for growth and development. Irrigated agriculture currently consumes the majority of total available water (up to 85%), making it critical for more efficient water use. Flood irrigation is widely practiced by the majority of the farmers (more than 85 %) with an efficiency which does not exceed 50%. In this context, a good knowledge of the partitioning of evapotranspiration (ET) into soil evaporation and plant transpiration is of crucial need for improving the irrigation scheduling and thus water use efficiency. In this study, the ISBA (Interactions Soil-Biosphere-Atmosphere) model was used for estimating ET and its partition over an olive orchard and a wheat field located near to the Marrakech City (Centre of Morocco). Two versions were evaluated: standard version which simulates a single energy balance for the soil and vegetation and the recently developed multiple energy balance (MEB) version which solves a separate energy balance for each of the two sources. Eddy covariance system, which provides the sensible and latent heat fluxes and meteorological instruments were operated during years 2003-2004 for the Olive Orchard and during years 2013 for wheat. The transpiration component was measured using a Sap flow system during summer over the wheat crop and stable isotope samples were gathered over wheat. The comparison between ET estimated by ISBA model and that measured by the Eddy covariance system showed that MEB version yielded a remarkable improvement compared to the standard version. The root mean square error (RMSE) and the correlation coefficient (R²) were about 45wm-2 and 0.8 for MEB version. By contrast, for the standard version, the RMSE and R² were about 60wm-2 and 0.7, respectively. The result also showed that

  7. Systematic revision of the marbled velvet geckos (Oedura marmorata species complex, Diplodactylidae) from the Australian arid and semi-arid zones.

    Science.gov (United States)

    Oliver, Paul M; Doughty, Paul

    2016-03-08

    Lizards restricted to rocky habitats often comprise numerous deeply divergent lineages, reflecting the disjunct nature of their preferred habitat and the capacity of rocky habitats to function as evolutionary refugia. Here we review the systematics and diversity of the predominantly saxicoline Australian marbled velvet geckos (genus Oedura) in the Australian arid and semi-arid zones using newly-gathered morphological data and previously published genetic data. Earlier work showed that four largely allopatric and genetically divergent lineages are present: Western (Pilbara and Gascoyne regions), Gulf (west and south of the Gulf of Carpentaria), Central (central ranges) and Eastern (Cooper and Darling Basins). None of these four populations are conspecific with true O. marmorata, a seperate species complex that is restricted to the Top End region of the Northern Territory. Top End forms share a short, bulbous tail whereas the other four lineages treated here possess a long, tapering tail. Morphological differences among the arid and semi-arid lineages include smaller body size, tapering lamellae and a shorter tail for the Gulf population, and a partially divided rostral scale in the Western population compared to the Central and Eastern populations. Accordingly, we resurrect O. cincta de Vis from synonymy for the Central and Eastern lineages, and regard this species as being comprised of two evolutionary significant units. We also describe the Gulf and Western lineages as new species: Oedura bella sp. nov. and O. fimbria sp. nov., respectively. We note that a predominantly arboreal lineage (the Eastern lineage of O. cincta) is more widely distributed than the other lineages and is phylogenetically nested within a saxicoline clade, but tends to have a deeper head and shorter limbs, consistent with morphological variation observed in other lizard radiations including both saxicoline and arboreal taxa.

  8. Soil microbial community structure is unaltered by plant invasion, vegetation clipping, and nitrogen fertilization in experimental semi-arid grasslands

    Directory of Open Access Journals (Sweden)

    Chelsea J Carey

    2015-05-01

    Full Text Available Global and regional environmental changes often co-occur, creating complex gradients of disturbance on the landscape. Soil microbial communities are an important component of ecosystem response to environmental change, yet little is known about how microbial structure and function respond to multiple disturbances, or whether multiple environmental changes lead to unanticipated interactive effects. Our study used experimental semi-arid grassland plots in a Mediterranean-climate to determine how soil microbial communities in a seasonally variable ecosystem respond to one, two, or three simultaneous environmental changes: exotic plant invasion, plant invasion + vegetation clipping (to simulate common management practices like mowing or livestock grazing, plant invasion + nitrogen (N fertilization, and plant invasion + clipping + N fertilization. We examined microbial community structure 5-6 years after plot establishment via sequencing of >1 million 16S rRNA genes. Abiotic soil properties (soil moisture, temperature, pH, and inorganic N and microbial functioning (nitrification and denitrification potentials were also measured and showed treatment-induced shifts, including altered NO3- availability, temperature, and nitrification potential. Despite these changes, bacterial and archaeal communities showed little variation in composition and diversity across treatments. Even communities in plots exposed to three interacting environmental changes were similar to those in restored native grassland plots. Historical exposure to large seasonal and inter-annual variations in key soil properties, in addition to prior site cultivation, may select for a functionally plastic or largely dormant microbial community, resulting in a microbial community that is structurally robust to single and multiple environmental changes.

  9. Achievements and prospects of genomics-assisted breeding in three legume crops of the semi-arid tropics.

    Science.gov (United States)

    Varshney, Rajeev K; Mohan, S Murali; Gaur, Pooran M; Gangarao, N V P R; Pandey, Manish K; Bohra, Abhishek; Sawargaonkar, Shrikant L; Chitikineni, Annapurna; Kimurto, Paul K; Janila, Pasupuleti; Saxena, K B; Fikre, Asnake; Sharma, Mamta; Rathore, Abhishek; Pratap, Aditya; Tripathi, Shailesh; Datta, Subhojit; Chaturvedi, S K; Mallikarjuna, Nalini; Anuradha, G; Babbar, Anita; Choudhary, Arbind K; Mhase, M B; Bharadwaj, Ch; Mannur, D M; Harer, P N; Guo, Baozhu; Liang, Xuanqiang; Nadarajan, N; Gowda, C L L

    2013-12-01

    Advances in next-generation sequencing and genotyping technologies have enabled generation of large-scale genomic resources such as molecular markers, transcript reads and BAC-end sequences (BESs) in chickpea, pigeonpea and groundnut, three major legume crops of the semi-arid tropics. Comprehensive transcriptome assemblies and genome sequences have either been developed or underway in these crops. Based on these resources, dense genetic maps, QTL maps as well as physical maps for these legume species have also been developed. As a result, these crops have graduated from 'orphan' or 'less-studied' crops to 'genomic resources rich' crops. This article summarizes the above-mentioned advances in genomics and genomics-assisted breeding applications in the form of marker-assisted selection (MAS) for hybrid purity assessment in pigeonpea; marker-assisted backcrossing (MABC) for introgressing QTL region for drought-tolerance related traits, Fusarium wilt (FW) resistance and Ascochyta blight (AB) resistance in chickpea; late leaf spot (LLS), leaf rust and nematode resistance in groundnut. We critically present the case of use of other modern breeding approaches like marker-assisted recurrent selection (MARS) and genomic selection (GS) to utilize the full potential of genomics-assisted breeding for developing superior cultivars with enhanced tolerance to various environmental stresses. In addition, this article recommends the use of advanced-backcross (AB-backcross) breeding and development of specialized populations such as multi-parents advanced generation intercross (MAGIC) for creating new variations that will help in developing superior lines with broadened genetic base. In summary, we propose the use of integrated genomics and breeding approach in these legume crops to enhance crop productivity in marginal environments ensuring food security in developing countries.

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

    Science.gov (United States)

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

    2015-12-01

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

  11. Quantifying the effects of stream channels on storm water quality in a semi-arid urban environment

    Science.gov (United States)

    Gallo, Erika L.; Lohse, Kathleen A.; Brooks, Paul D.; McIntosh, Jennifer C.; Meixner, Thomas; McLain, Jean E. T.

    2012-11-01

    SummaryStormwater drainage systems can have a large effect on urban runoff quality, but it is unclear how ephemeral urban streams alter runoff hydrochemistry. This problem is particularly relevant in semi-arid regions, where urban storm runoff is considered a renewable water resource. Here we address the question: how do stream channels alter urban runoff hydrochemistry? We collected synoptic stormwater samples during three rainfall-runoff events from nine ephemeral streams reaches (three concrete or metal, three grass, three gravel) in Tucson, Arizona. We identified patterns of temporal and spatial (longitudinal) variability in concentrations of conservative (chloride and isotopes of water) and reactive solutes (inorganic-N, soluble reactive phosphorous, sulfate-S, dissolved organic carbon (DOC) and nitrogen, and fecal indicator bacteria). Water isotopes and chloride (Cl) concentrations indicate that solute flushing and evapoconcentration alter temporal patterns in runoff hydrochemistry, but not spatial hydrochemical responses. Solute concentrations and stream channel solute sourcing and retention during runoff were significantly more variable at the grass reaches (CV = 2.3 - 144%) than at the concrete or metal (CV = 1.6 - 107%) or gravel reaches (CV = 1.9 - 60%), which functioned like flow-through systems. Stream channel soil Cl and DOC decreased following a runoff event (Cl: 12.1-7.3 μg g-1 soil; DOC: 87.7-30.1 μg g-1 soil), while soil fecal indicator bacteria counts increased (55-215 CFU g-1 soil). Finding from this study suggest that the characteristics of the ephemeral stream channel substrate control biogeochemical reactions between runoff events, which alter stream channel soil solute stores and the hydrochemistry of subsequent runoff events.

  12. Exceptionally high organic nitrogen concentrations in a semi-arid South Texas estuary susceptible to brown tide blooms

    Science.gov (United States)

    Wetz, Michael S.; Cira, Emily K.; Sterba-Boatwright, Blair; Montagna, Paul A.; Palmer, Terence A.; Hayes, Kenneth C.

    2017-03-01

    Studies of estuarine eutrophication have tended to focus on systems with continually flowing rivers, while little is known about estuaries from semi-arid/arid regions. Here we report results from an assessment of water quality conditions in Baffin Bay, Texas, a shallow (use. Chlorophyll a averaged 28-30 μg/l in Baffin Bay from 2003 to 2013 and total Kjeldahl nitrogen (TKN) concentrations were also very high (116-120 μM), with concentrations of both variables exceeding those of most other Texas estuaries by 2-5 fold. More recent field sampling (2013-2015) showed that dissolved organic nitrogen concentrations in Baffin Bay (62 ± 14 μM) were >2 fold higher than in three other Texas estuaries. In contrast, inorganic nitrogen (ammonium, nitrate) and phosphate concentrations were relatively low. Statistically significant long-term annual increases in chlorophyll a and salinity were observed in Baffin Bay, while long-term seasonal increases were observed for water temperature and TKN. Overall, Baffin Bay is displaying multiple symptoms of eutrophication, namely very high organic carbon, organic nitrogen and chlorophyll concentrations, as well as symptoms not quantified here such as fish kills and episodic hypoxia. Much of the increase in chlorophyll in Baffin Bay, at least since ∼1990, have coincided with blooms of the mixotrophic phytoplankton species, Aureoumbra lagunensis, which is thought to be favored under high proportions of organic to inorganic nitrogen. Thus the high and possibly increasing organic nitrogen concentrations, coupled with a long-term annual increase in salinity and a long-term seasonal increase in water temperature are likely to promote additional brown tide blooms in this system in the future.

  13. Microclimate-induced Lateral Channel Migration as a Driver for Hillslope Asymmetry in Semi-arid Landscapes

    Science.gov (United States)

    Richardson, P. W.; Perron, J. T.; Miller, S. R.

    2014-12-01

    North-facing slopes in semi-arid regions of the northern hemisphere are commonly steeper than south-facing slopes, whereas the converse is observed in the southern hemisphere. In the absence of a structural cause, the most common explanations for topographic asymmetry ultimately invoke aspect-related microclimate. Landscapes with asymmetric topography are therefore potential natural laboratories for investigating the sensitivity of surface processes to climate. However, the specific mechanisms driving asymmetry are not well understood, and studies using asymmetric topography to investigate landscape climate sensitivity may have to consider multiple origins of the asymmetry. Two leading hypotheses have emerged. One states that small differences in microclimate cause differences in the efficiency of erosional processes on slopes with different aspect. The more efficiently eroding slope erodes faster until the resulting slope asymmetry compensates for the difference in erosional efficiency. According to the other hypothesis, the difference in erosional efficiency is not sufficient to create the observed topographic asymmetry. Instead, sediment aggradation at the foot of the more quickly eroding slope forces lateral channel migration and undercutting of the opposing slope. These two explanations for topographic asymmetry predict different trajectories of long-term landscape evolution - sustained migration of asymmetric valleys would drive stream capture and drainage reorganization, whereas the mechanism without lateral channel migration would not - but there is no existing test capable of distinguishing between them. We develop such a test using a landscape evolution model that simulates different asymmetry-forming mechanisms, including asymmetric runoff production, channel incision threshold, soil creep, and lateral channel migration. For the case of topographic asymmetry produced by lateral channel migration, the model predicts that north-facing hilltops should be

  14. The influence of several changes in atmospheric states over semi-arid areas on the incidence of mental health disorders

    Science.gov (United States)

    Yackerson, Naomy S.; Zilberman, Arkadi; Todder, Doron; Kaplan, Zeev

    2011-05-01

    The incidence of suicide attempts [Deliberate Self Harm (DSH); ICD-10: X60-X84] and psychotic attacks (PsA; ICD-10, F20-F29) in association with atmospheric states, typical for areas close to big deserts, was analyzed. A retrospective study is based on the 4,325 cases of DSH and PsA registered in the Mental Health Center (MHC) of Ben-Gurion University (Be'er-Sheva, Israel) during 2001-2003. Pearson and Spearman test correlations were used; the statistical significance was tested at p 0.1). Correlation coefficients between N SU and N PS and speed WS of westerly wind reaches 0.3 ( p 0.09). Variations in easterly wind direction WD influence N SU and N PS values ( p 0.3). Obviously ,in transition areas located between different regions ,the main role of air streams in meteorological-biological impact can scarcely be exaggerated. An unstable balance in the internal state of a weather-sensitive person is disturbed when the atmospheric state is changed by specific desert winds, which can provoke significant perturbations in meteorological parameters. Results indicate the importance of wind direction, defining mainly the atmospheric situation in semi-arid areas: changes in direction of the easterly wind influence N SU and N PS , while changes in WS are important for mental health under westerly air streams. Obviously, N SU and N PS are more affected by the disturbance of weather from its normal state, for a given season, to which the local population is accustomed, than by absolute values of meteorological parameters.

  15. Changes of AM fungal abundance along environmental gradients in the arid and semi-arid grasslands of northern China.

    Directory of Open Access Journals (Sweden)

    Yajun Hu

    Full Text Available Arbuscular mycorrhizal (AM fungi are ubiquitous symbionts of higher plants in terrestrial ecosystems, while the occurrence of the AM symbiosis is influenced by a complex set of abiotic and biotic factors. To reveal the regional distribution pattern of AM fungi as driven by multiple environmental factors, and to understand the ecological importance of AM fungi in natural ecosystems, we conducted a field investigation on AM fungal abundance along environmental gradients in the arid and semi-arid grasslands of northern China. In addition to plant parameters recorded in situ, soil samples were collected, and soil chemo-physical and biological parameters were measured in the lab. Statistical analyses were performed to reveal the relative contribution of climatic, edaphic and vegetation factors to AM fungal abundance, especially for extraradical hyphal length density (HLD in the soil. The results indicated that HLD were positively correlated with mean annual temperature (MAT, soil clay content and soil pH, but negatively correlated with both soil organic carbon (SOC and soil available N. The multiple regressions and structural equation model showed that MAT was the key positive contributor and soil fertility was the key negative contributor to HLD. Furthermore, both the intraradical AM colonization (IMC and relative abundance of AM fungi, which was quantified by real-time PCR assay, tended to decrease along the increasing SOC content. With regard to the obvious negative correlation between MAT and SOC in the research area, the positive correlation between MAT and HLD implied that AM fungi could potentially mitigate soil carbon losses especially in infertile soils under global warming. However, direct evidence from long-term experiments is still expected to support the AM fungal contribution to soil carbon pools.

  16. Changes of AM fungal abundance along environmental gradients in the arid and semi-arid grasslands of northern China.

    Science.gov (United States)

    Hu, Yajun; Rillig, Matthias C; Xiang, Dan; Hao, Zhipeng; Chen, Baodong

    2013-01-01

    Arbuscular mycorrhizal (AM) fungi are ubiquitous symbionts of higher plants in terrestrial ecosystems, while the occurrence of the AM symbiosis is influenced by a complex set of abiotic and biotic factors. To reveal the regional distribution pattern of AM fungi as driven by multiple environmental factors, and to understand the ecological importance of AM fungi in natural ecosystems, we conducted a field investigation on AM fungal abundance along environmental gradients in the arid and semi-arid grasslands of northern China. In addition to plant parameters recorded in situ, soil samples were collected, and soil chemo-physical and biological parameters were measured in the lab. Statistical analyses were performed to reveal the relative contribution of climatic, edaphic and vegetation factors to AM fungal abundance, especially for extraradical hyphal length density (HLD) in the soil. The results indicated that HLD were positively correlated with mean annual temperature (MAT), soil clay content and soil pH, but negatively correlated with both soil organic carbon (SOC) and soil available N. The multiple regressions and structural equation model showed that MAT was the key positive contributor and soil fertility was the key negative contributor to HLD. Furthermore, both the intraradical AM colonization (IMC) and relative abundance of AM fungi, which was quantified by real-time PCR assay, tended to decrease along the increasing SOC content. With regard to the obvious negative correlation between MAT and SOC in the research area, the positive correlation between MAT and HLD implied that AM fungi could potentially mitigate soil carbon losses especially in infertile soils under global warming. However, direct evidence from long-term experiments is still expected to support the AM fungal contribution to soil carbon pools.

  17. Diversity of Plant Species and Communities Complexity in Artificial Fencing Region of Semi-Arid Area──A Case Study of Yanchi County of Ningxia%半干旱区人工封育草场植物群落物种多样性与复杂性研究──以宁夏盐池为例

    Institute of Scientific and Technical Information of China (English)

    刘小丹; 李瑞; 张克斌; 艾哈迈德·比拉勒

    2014-01-01

    shows the impacts of artificial fencing on the diversity and complexity of communities in the process of vegetation restoration which will inevitably help to reveal the mechanism of ecological restoration. Currently there is few research studies of combining both species diversity and complexity measure are used to study the quantitative structure of plant communities, with few reports on grassland ecosystem. The plant communities in artificial fencing pasture in semi-arid area were explored in this study. The diversity and complexity measure were used to study of the diversity and complexity of plant communities, as well as the relationship between complexity and species diversity. The results showed that:(1) the richness values in old and new fencing areas were higher than in the contrast area which indicated that fencing helped to increase species richness. Long-time fencing would occur regularly richness fluctuations to pasture vegetation, and frequency of occurrence of the high and low peak value was about 4 to 5 years/time. Most of diversity index values i.e. Shannon-Wiener diversity(SW)and Simpson diversity(SP)in old and new fencing areas were also higher than in the contrast area, which indicated that fencing measure increased the diversity of grassland vegetation. Species diversity indices were significantly influenced by precipitation, when precipitation increased or decreased, the diversity index also appeared to increase or decrease accordingly, but the rainfall has also a positive effect. Uniformity changes in old and new fencing areas were relatively stable, and the index values were higher than in the contrast area, which indicated that fencing helped to increase evenness. Most of complexity index values i.e. total complexity index and disorder-based complexity index in old and new fencing areas were higher than in the contrast area while the index changes were relatively stable which illustrated that communities structure in fencing areas were more

  18. Monitoring temperature sensitivity of soil organic carbon decomposition under maize-wheat cropping systems in semi-arid India.

    Science.gov (United States)

    Sandeep, S; Manjaiah, K M; Mayadevi, M R; Singh, A K

    2016-08-01

    Long-term storage of soil organic carbon (SOC) is essential for sustainability of agricultural ecosystems and maintaining overall environment quality as soils contain a significant part of global carbon stocks. In this study, we attempted to explain the carbon mineralization and temperature sensitivity of SOC in maize-wheat systems, a common cropping system in the semi-arid regions of India. Soil samples(0-0.15 m) from long-term experimental plots laid in split plot design with two tillage systems (conventional tillage and bed planting) and six nutrient management treatments (T 1 = control, T 2 = 120 kg urea-N/ha, T 3 = T2 (25 % N substituted by farmyard manure (FYM)), T 4 = T 2 (25 % N substituted by sewage sludge), T 5 = T 2 + crop residue, T 6 = 100 % recommended doses of N through organic source - 50 % FYM + 25 % biofertilizer + 25 % crop residue) were incubated at different temperatures (25, 30, 35, and 40 °C) to determine the thermal sensitivity parameters associated with carbon mineralization. Earlier reports suggest a selective preservation of C3-derived carbon fractions over C4 in the SOC pool, and this is the first instance where δ (13)C signatures (C4-derived carbon) were used as a qualitative measure to assess thermal sensitivity of SOC pools in the maize-wheat crop rotation systems of semi-arid India. Among the nutrient management treatments, mineral fertilizers were found to add more C4-derived carbon to the SOC pool in both the tillage systems but shows less promise in SOC stability as indicated by their lower activation energies (Ea) (14.25 kJ mol(-1)). Conventional tillage was found to mineralize 18.80 % (T 1-control at 25 °C) to 29.93 % carbon (T 3-mineral fertilizer + FYM at 40 °C) during the 150 days of incubation which was significantly higher than bed planting system (14.90 % in T 1-control at 25 °C and 21.99 % in T 6-100% organic sources at 40 °C). Organic manures, especially FYM (19

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

    Science.gov (United States)

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

    2016-01-01

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

  20. Responses of desert, semi-arid grassland and scrub-oak ecosystems to elevated CO2

    Science.gov (United States)

    Luus, Kristina; Walker, Anthony; de Kauwe, Martin; Hungate, Bruce; Megonigal, J. Patrick; Lu, Meng; Fenstermaker, Lynn; Nowak, Robert; Morgan, Jack; Medlyn, Belinda; Norby, Richard; Zaehle, Sönke

    2014-05-01

    We compared observations from free air CO2 enrichment (FACE) experiments at dry (desert, semi-arid grassland and scrub-oak) sites, to predictions from a suite of ecosystem models with differing complexity, ranging from a parsimonious forest growth model (GDAY) to a comprehensive land surface model (OCN). Dry ecosystems have often been predicted to increase in net primary productivity (NPP) and net C uptake over time in response to elevated CO2 (eCO2) because of increased N fixation, and alleviation of drought-stress due to reduced stomatal conductance. However, experiments at the Nevada Desert FACE (NDFF), the semi-arid prairie grassland FACE (PHACE), and the scrub-oak Kennedy Space Center open-top chamber experiment (KSCO), have revealed that dry ecosystems display a more complex biogeochemical response to eCO2. Insights into the processes determining the responses of dry ecosystems to eCO2 were gained by evaluating model estimates against site data, and by dissecting model responses to eCO2. Site level findings at PHACE indicated that eCO2 enabled more rapid C turnover, resulting in a net ecosystem C loss. Conversely, at PHACE, models such as OCN simulated a decrease in N leaching and an increase in NPP because of eCO2, leading to increased C storage. Leaf cover and NPP at KSCO initially increased with eCO2 before declining due to reduced N fixation and increased N leaching. At NDFF, eCO2 only increased plant growth during one abnormally wet year; in subsequent years, soil crust cyanobacteria decreased in abundance, and gains in biomass were not sustained. In OCN simulations at NDFF, eCO2 increased water-use efficiency and NPP in years with average to above-average precipitation. Through examination of the reasons for discrepancies between observed and modeled ecosystem responses to eCO2, processes determining the biogeochemical responses of dry ecosystems to eCO2 were elucidated.

  1. The role of the perch effect on the nucleation process in Mediterranean semi-arid oldfields

    Science.gov (United States)

    Pausas, Juli G.; Bonet, Andreu; Maestre, Fernando T.; Climent, Anna

    2006-05-01

    Oldfield succession in Mediterranean ecosystems has been studied extensively in mesic conditions. However, this phenomenon is still poorly understood in semi-arid Mediterranean areas, where reduced plant cover, the importance of facilitation processes and the role of abiotic factors make these environments distinct. We first test whether the carob tree ( Ceratonia siliqua) generates nucleation patterns in semi-arid oldfields, and to what extent such patterns change with abandonment age. Then we test to what extent nucleation can be explained by the perch effect. And finally, we test whether the nucleated pattern around carob trees is a source of diversity in the oldfields studied. To answer these questions we located oldfields abandoned 25 and 50 years ago (20 in each case) in the Alacant Province (SE Spain, Iberian Peninsula) on the basis of aerial photographs and personal interviews with local landowners and managers. In each oldfield woody plant density and richness were sampled on two microsites: under the carob tree and in the open field. Analysis was performed on all woody plants and by separating the species in two functional groups: fleshy-fruited (with fleshy mesocarp) and non-fleshy-fruited species. The results suggest that woody vegetation colonising abandoned C. siliqua fields in SE Spain is not randomly distributed but follows a nucleation pattern with higher plant density under the trees. However, the nucleation pattern is only significant for fleshy-fruited species, suggesting that facilitative interactions alone cannot explain the nucleation pattern and that the perch effect plays an important role. The results also show that the nucleation pattern (total plant density and density of non-fleshy-fruited plants) did not increase with abandonment age, while the perch effect (density of fleshy-fruited plants) did increase significantly. Furthermore, the results also show that the nucleation pattern is not only a loci of high plant density but also a

  2. Combined effects of nitrogen addition and litter manipulation on nutrient resorption of Leymus chinensis in a semi-arid grassland of northern China.

    Science.gov (United States)

    Li, X; Liu, J; Fan, J; Ma, Y; Ding, S; Zhong, Z; Wang, D

    2015-01-01

    Plant growth in semi-arid ecosystems is usually severely limited by soil nutrient availability. Alleviation of these resource stresses by fertiliser application and aboveground litter input may affect plant internal nutrient cycling in such regions. We conducted a 4-year field experiment to investigate the effects of nitrogen (N) addition (10 g N·m(-2) ·year(-1)) and plant litter manipulation on nutrient resorption of Leymus chinensis, the dominant native grass in a semi-arid grassland in northern China. Although N addition had no clear effects on N and phosphorus (P) resorption efficiencies in leaves and culms, N fertilisation generally decreased leaf N resorption proficiency by 54%, culm N resorption proficiency by 65%. Moreover, N fertilisation increased leaf P resorption proficiency by 13%, culm P resorption proficiency by 20%. Under ambient or enriched N conditions, litter addition reduced N and P resorption proficiencies in both leaves and culms. The response of P resorption proficiency to litter manipulation was more sensitive than N resorption proficiency: P resorption proficiency in leaves and culms decreased strongly with increasing litter amount under both ambient and enriched N conditions. In contrast, N resorption proficiency was not significantly affected by litter addition, except for leaf N resorption proficiency under ambient N conditions. Furthermore, although litter addition caused a general decrease of leaf and culm nutrient resorption efficiencies under both ambient and enriched N conditions, litter addition effects on nutrient resorption efficiency were much weaker than the effects of litter addition on nutrient resorption proficiency. Taken together, our results show that leaf and non-leaf organs of L. chinensis respond consistently to altered soil N availability. Our study confirms the strong effects of N addition on plant nutrient resorption processes and the potential role of aboveground litter, the most important natural fertiliser in

  3. Assessing the biophysical and socio-economic potential of Sustainable Land Management and Water Harvesting Technologies for rainfed agriculture across semi-arid Africa.

    Science.gov (United States)

    Irvine, Brian; Fleskens, Luuk; Kirkby, Mike

    2016-04-01

    Stakeholders in recent EU projects identified soil erosion as the most frequent driver of land degradation in semi-arid environments. In a number of sites, historic land management and rainfall variability are recognised as contributing to the serious environmental impact. In order to consider the potential of sustainable land management and water harvesting techniques stakeholders and study sites from the projects selected and trialled both local technologies and promising technologies reported from other sites . The combined PESERA and DESMICE modelling approach considered the regional effects of the technologies in combating desertification both in environmental and socio-economical terms. Initial analysis was based on long term average climate data with the model run to equilibrium. Current analysis, primarily based on the WAHARA study sites considers rainfall variability more explicitly in time series mode. The PESERA-DESMICE approach considers the difference between a baseline scenario and a (water harvesting) technology scenario, typically, in terms of productivity, financial viability and scope for reducing erosion risk. A series of 50 year rainfall realisations are generated from observed data to capture a full range of the climatic variability. Each realisation provides a unique time-series of rainfall and through modelling can provide a simulated time-series of crop yield and erosion risk for both baseline conditions and technology scenarios. Subsequent realisations and model simulations add to an envelope of the potential crop yield and cost-benefit relations. The development of such envelopes helps express the agricultural and erosional risk associated with climate variability and the potential for conservation measures to absorb the risk, highlighting the probability of achieving a given crop yield or erosion limit. Information that can directly inform or influence the local adoption of conservation measures under the climatic variability in semi-arid

  4. Forecasting of cereals yields in a semi-arid area using the agrometeorological model «SAFY» combined to optical SPOT/HRV images

    Science.gov (United States)

    Chahbi, Aicha; Zribi, Mehrez; Lili-Chabaane, Zohra; Mougenot, Bernard

    2015-10-01

    In semi-arid areas, an operational grain yield forecasting system, which could help decision-makers to plan annual imports, is needed. It can be challenging to monitor the crop canopy and production capacity of plants, especially cereals. Many models, based on the use of remote sensing or agro-meteorological models, have been developed to estimate the biomass and grain yield of cereals. Remote sensing has demonstrated its strong potential for the monitoring of the vegetation's dynamics and temporal variations. Through the use of a rich database, acquired over a period of two years for more than 60 test fields, and from 20 optical satellite SPOT/HRV images, the aim of the present study is to evaluate the feasibility of two approaches to estimate the dynamics and yields of cereals in the context of semi-arid, low productivity regions in North Africa. The first approach is based on the application of the semi-empirical growth model SAFY "Simple Algorithm For Yield estimation", developed to simulate the dynamics of the leaf area index and the grain yield, at the field scale. The model is able to reproduce the time evolution of the LAI of all fields. However, the yields are under-estimated. Therefore, we developed a new approach to improve the SAFY model. The grain yield is function of LAI area in the growth period between 25 March and 5 April. This approach is robust, the measured and estimated grain yield are well correlated. Finally, this model is used in combination with remotely sensed LAI measurements to estimate yield for the entire studied site.

  5. New Brazilian Cerambycidae from the Amazonian region (Coleoptera)

    Science.gov (United States)

    Santos-Silva, Antonio; Galileo, Maria Helena M.

    2016-01-01

    Abstract Three new species of Cerambycidae are described from the Brazilian Amazonian region: Psapharochrus bezarki (Lamiinae, Acanthoderini); Xenofrea ayri (Lamiinae, Xenofreini); and Mecometopus wappesi (Cerambycinae, Clytini). Mecometopus wappesi is added to a previous key. PMID:27551200

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

    Science.gov (United States)

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

    2016-04-01

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

  7. Canopy management effects on ‘Syrah’ grapevines under tropical semi-arid conditions

    Directory of Open Access Journals (Sweden)

    Patrícia Coelho de Souza Leão

    2016-06-01

    Full Text Available ABSTRACT The aim of this study was to evaluate the effects of shoot topping and leaf removal practices on vegetative vigor, yield and physicochemical characteristics of the 'Syrah' grape in the semi-arid tropical climate conditions of the São Francisco River Valley in the northeast of Brazil. The experiment was conducted over five growing cycles from 2010 to 2012 in a 'Syrah' commercial vineyard in the municipality of Casa Nova, Bahia, Brazil. Treatments consisted of leaf removal once or twice during fruit set or at the beginning of bunch closure, and one or two shoot toppings of the berry when pea-sized or 10 days after berry growth had commenced. Leaf removal and shoot topping did not affect yield, plant vigor components nor the main attributes of fruit quality. In contrast, there was a seasonal effect with higher yield and better balance between production and vigor in grapes produced in the first half of 2012. The Syrah grape quality was favored in cycles in the first half of the year when its ripening phase coincided with the period of mild temperatures.

  8. Seasonality of vesicular-arbuscular mycorrhizae in sedges in a semi-arid tropical grassland

    Science.gov (United States)

    Muthukumar, T.; Udaiyan, K.

    2002-10-01

    Vesicular-arbuscular mycorrhizal (VAM) colonization and spore numbers in the rhizosphere of Cyperus iria L. and C. rotundus L., growing in a semi-arid tropical grassland, was studied during the 1993 and 1994 monsoons. In addition, climatic and chemical properties of the soils were determined in order to investigate their influence on mycorrhizal variables. VAM fungal association in the sedges was confirmed by plant- and root-trap culture techniques. The soil nutrients exhibited seasonal variations, but were highly variable between years. Intercellular hyphae and vesicles with occasional intraradical spores characterized mycorrhizal association in sedges. Dark septate fungi also colonized roots of sedges. Temporal variations in mycorrhizal colonization and spore numbers occurred, indicating seasonality. However, the patterns of mycorrhizal colonization and spore numbers were different during both the years. The VAM fungal structures observed were intercellular hyphae and vesicles. Changes in the proportion of root length with VAM structures, total colonization levels and spore numbers were related to climatic and edaphic factors. However, the intensity of influence of climatic and soil factors on VAM tended to vary with sedge species.

  9. Analysis of Precipitation Characteristics during 1957-2012 in the Semi-Arid Loess Plateau, China.

    Science.gov (United States)

    Zhao, Weijun; Yu, Xinyang; Ma, Huan; Zhu, Qingke; Zhang, Yan; Qin, Wei; Ai, Ning; Wang, Yu

    2015-01-01

    Precipitation is the only water supply and most important factor affecting vegetation growth on the slopes of semi-arid Loess Plateau of China. Based on precipitation data from 7 synoptic stations in the study area over the period 1957-2012, the trends of precipitation and standardized precipitation index (SPI) were analyzed by using linear regression, Mann-Kendall, and Spearman's Rho tests at the 5% significance level. The results show that (1) the precipitation fluctuation of monthly precipitation was intense (coefficients of variation> 100%), and the drier years were recorded as 1965 and 1995 at all stations. (2) The significant change trend of different stations varied on different time scales: the Changwu station had a significant decreasing trend in April (-0.488 mm/year) and November (-0.249 mm/year), while Luochuan station was in April (-0.457 mm/year); Changwu station displayed a significant increasing trends in winter (0.220 mm/year) and a significant decreasing trends in spring (-0.770 mm/year). The significant decreasing trends in annual precipitation were detected at the Suide (-2.034 mm/year) and Yan'an (-2.129 mm/year) stations. (3) The SPI-12 series analysis suggests that the drought degree of Yulin and Changwu was the lowest and that of Hengshan was the highest among the 7 synoptic stations.

  10. Farming system context drives the value of deep wheat roots in semi-arid environments.

    Science.gov (United States)

    Lilley, Julianne M; Kirkegaard, John A

    2016-06-01

    The capture of subsoil water by wheat roots can make a valuable contribution to grain yield on deep soils. More extensive root systems can capture more water, but leave the soil in a drier state, potentially limiting water availability to subsequent crops. To evaluate the importance of these legacy effects, a long-term simulation analysis at eight sites in the semi-arid environment of Australia compared the yield of standard wheat cultivars with cultivars that were (i) modified to have root systems which extract more water at depth and/or (ii) sown earlier to increase the duration of the vegetative period and hence rooting depth. We compared simulations with and without annual resetting of soil water to investigate the legacy effects of drier subsoils related to modified root systems. Simulated mean yield benefits from modified root systems declined from 0.1-0.6 t ha(-1) when annually reset, to 0-0.2 t ha(-1) in the continuous simulation due to a legacy of drier soils (mean 0-32mm) at subsequent crop sowing. For continuous simulations, predicted yield benefits of >0.2 t ha(-1) from more extensive root systems were rare (3-10% of years) at sites with shallow soils (extensively has implications for the farming system productivity, and the crop sequence must be managed tactically to optimize overall system benefits.

  11. Determination of seasonal rainfall variability, onset and cessation in semi-arid Tharaka district, Kenya

    Science.gov (United States)

    Recha, C. W.; Makokha, G. L.; Traore, P. S.; Shisanya, C.; Lodoun, T.; Sako, A.

    2012-05-01

    The study quantified rainfall variability for March-May (MAM) and October-December (OND) seasons in Tharaka district, Kenya. The parameters analysed were inter-annual variability of seasonal rainfall, onset and cessation using daily rainfall data in three agro-ecological zones' stations. Percentage mean cumulative method was used to determine onset and cessation, and seasonal variability was estimated using rainfall variability indices. Although both seasons are highly variable, OND has been persistently below mean over time while MAM shows high within-season variability. Despite the near uniformity in the mean onset and cessation dates, the former is highly variable on an inter-annual scale. The two rainfall seasons are inherently dissimilar and therefore require specific cropping in agro-ecological zone LM4 and LM4-5. It is possible that farmers in IL5 are missing an opportunity by under-utilising MAM rainfall. The results should be incorporated in implications of climate variability and vulnerability assessment in semi-arid Tharaka district.

  12. Growth and production of irrigated vitória pineapple grown in semi-arid conditions

    Directory of Open Access Journals (Sweden)

    Rodinei Facco Pegoraro

    2014-09-01

    Full Text Available This study aimed to evaluate the growth characteristics of irrigated Vitória pineapple plants grown in semi-arid conditions and determine its developmental stages based on those characteristics. It was used a randomized block design with four replicates. The experimental treatments were: plant harvest at 270, 330, 390, 450, 510, 570, 690, 750, and 810 days after planting (DAP. The following variables were determined: plant height, stem diameter, D-leaf length, D-leaf fresh and dry mass, biomass production of plants and plant parts (organs, and vegetative biomass. Five phenological stages are proposed based on vegetative biomass production: 80% (V5. The maximum growth rate for plant height, D-leaf length, and stem diameter was observed at the end of the phenological stage V1 (390-411 DAP, and at the end of stage V5 these plant traits had average values of 106, 82, and 7 cm, respectively. The maximum biomass accumulation rates were observed at stages V4 and V5, resulting in a final fruit yield and total fresh biomass of 72 t ha-1 and 326 t ha-1, respectively. Finally, we estimated that 80% of the accumulated biomass may remain in the field after fruit and slip harvest, and could be incorporated as plant residue into the soil.

  13. Remote sensing to monitor monotypic weed patches in semi-arid grasslands

    Science.gov (United States)

    Planck, Laura

    Remote sensing technology has great potential for mapping weed distributions. Fine-scale weed distribution maps can provide means to evaluate the success of weed control methods, to guide selection of future control methods, and to examine factors that influence the creation and persistence of monotypic weed patches. Here I examined the effectiveness of different classification approaches in detecting dense monotypic patches of the late-phenology weeds Taeniatherum caput-medusae (medusahead) and Aegilops triuncialis (barbed goatgrass), among cool-season forage grasses (Bromus spp. and Avena spp.) across multiple years in semi-arid rangelands in northern California (USA). I found that color infrared photographs acquired at two key phenological periods produced more accurate classifications than those based on one image alone, and that inclusion of training sites did not improve the overall accuracy of a classification. I also examined the association of remnant litter with transitions in species dominance in medusahead, goatgrass or forage patches. Persistence of goatgrass-dominated patches was correlated with the amount of remnant litter present, but surprisingly that of medusahead was not, suggesting a potential need for different strategies in control of these two noxious species. Overall, this study shows that remote sensing can be used to create weed distribution maps of phenologically distinct species, and help us further understand community response to invasion and evaluate the effectiveness of management treatments.

  14. Evaluating pasture and soil allowance of manganese for Kajli rams grazing in semi-arid environment.

    Science.gov (United States)

    Khan, Zafar Iqbal; Ahmad, Kafeel; Ashraf, Muhammad; Naqvi, Syed Ali Hassan; Seidavi, Alireza; Akram, Nudrat Aisha; Laudadio, Vito; Tufarelli, Vincenzo

    2015-03-01

    The current research on the manganese (Mn) transfer from soil to plant as well as to grazing Kajli rams in the form of sampling periods was carried out under semi-arid environmental conditions. Forage, soil and blood plasma samples were collected during 4 months of the year after a 1-month interval, and Mn concentrations were assessed after wet digestion using an atomic absorption spectrophotometer. Results showed that Mn concentration in soil ranged from 48.28 to 59.44 mg/kg, with incoherent augment and decline across sampling periods, and effect of sampling period on soil Mn was also found to be significant (P crop requirement. The Mn concentration in forage ranged between 24.8 and 37.2 mg/kg, resulting deficient based on the requirement allowance of Mn for livestock grazing animals, therein with almost unchanged forage Mn concentration. The Mn values in blood plasma of rams varied from 0.066 to 0.089 mg/l, with a consistent increase based on sampling period, and the effect of sampling periods on plasma Mn was found to be highly significant (P crop residues and mixed pasture and a pronounced seasonal supply of Mn at the four sampling period of grazing land of diverse botanical composition.

  15. Impacts of Climate Anomalies on the Vegetation Patterns in the Arid and Semi-Arid Zones of Uzbekistan

    Science.gov (United States)

    Dildora, Aralova; Toderich, Kristina; Dilshod, Gafurov

    2016-08-01

    Steadily rising temperature anomalies in last decades are causing changes in vegetation patterns for sensitive to climate change in arid and semi-arid dryland ecosystems. After desiccation of the Aral Sea, Uzbekistan has been left with the challenge to develop drought and heat stress monitoring system and tools (e.g., to monitor vegetation status and/crop pattern dynamics) with using remote sensing technologies in broad scale. This study examines several climate parameters, NDVI and drought indexes within geostatistical method to predict further vegetation status in arid and semi-arid zones of landscapes. This approaches aimed to extract and utilize certain variable environmental data (temperature and precipitation) for assessment and inter-linkages of vegetation cover dynamics, specifically related to predict degraded and recovered zones or desertification process in the drylands due to scarcity of water resources and high risks of climate anomalies in fragile ecosystem of Uzbekistan.

  16. Deriving seasonal dynamics in ecosystem properties of semi-arid savannas using in situ based hyperspectral reflectance

    Directory of Open Access Journals (Sweden)

    T. Tagesson

    2015-02-01

    infrared (ρ1295 wavelengths. NDSI combining near infrared and shortwave infrared were strongly affected by solar zenith angles and sensor viewing geometry, as were many combinations of visible wavelengths. This study provides analyses based upon novel multi-angular hyperspectral data for validation of Earth Observation based properties of semi-arid ecosystems, as well as insights for designing spectral characteristics of future sensors for ecosystem monitoring.

  17. Carbon dioxide emissions from semi-arid soils amended with biochar alone or combined with mineral and organic fertilizers.

    Science.gov (United States)

    Fernández, José M; Nieto, M Aurora; López-de-Sá, Esther G; Gascó, Gabriel; Méndez, Ana; Plaza, César

    2014-06-01

    Semi-arid soils cover a significant area of Earth's land surface and typically contain large amounts of inorganic C. Determining the effects of biochar additions on CO2 emissions from semi-arid soils is therefore essential for evaluating the potential of biochar as a climate change mitigation strategy. Here, we measured the CO2 that evolved from semi-arid calcareous soils amended with biochar at rates of 0 and 20tha(-1) in a full factorial combination with three different fertilizers (mineral fertilizer, municipal solid waste compost, and sewage sludge) applied at four rates (equivalent to 0, 75, 150, and 225kg potentially available Nha(-1)) during 182 days of aerobic incubation. A double exponential model, which describes cumulative CO2 emissions from two active soil C compartments with different turnover rates (one relatively stable and the other more labile), was found to fit very well all the experimental datasets. In general, the organic fertilizers increased the size and decomposition rate of the stable and labile soil C pools. In contrast, biochar addition had no effects on any of the double exponential model parameters and did not interact with the effects ascribed to the type and rate of fertilizer. After 182 days of incubation, soil organic and microbial biomass C contents tended to increase with increasing the application rates of organic fertilizer, especially of compost, whereas increasing the rate of mineral fertilizer tended to suppress microbial biomass. Biochar was found to increase both organic and inorganic C contents in soil and not to interact with the effects of type and rate of fertilizer on C fractions. As a whole, our results suggest that the use of biochar as enhancer of semi-arid soils, either alone or combined with mineral and organic fertilizers, is unlikely to increase abiotic and biotic soil CO2 emissions.

  18. Parameterization of almanac crop simulation model for non-irrigated dry bean in semi-arid temperate areas in Mexico

    OpenAIRE

    Alma Delia Baez-Gonzalez; James R. Kiniry; Jose Saul Padilla Ramirez; Guillermo Medina Garcia; Jose Luis Ramos Gonzalez; Esteban Salvador Osuna Ceja

    2015-01-01

    Dry bean simulation models can be used to make management decisions when properly parameterized. This study aimed to parameterize the ALMANAC (Agricultural Land Management Alternatives with Numerical Assessment Criteria) crop simulation model for dry bean in the semi-arid temperate areas of Mexico. The parameterization process was based on data from two important non-irrigated dry bean fields in Mexico. The parameters were potential heat units (PHU), leaf area index (LAI) and harvest index (H...

  19. Water quality assessment of highly polluted rivers in a semi-arid Mediterranean zone Oued Fez and Sebou River (Morocco)

    OpenAIRE

    2014-01-01

    Oued Fez (one of the Sebou River tributaries - Morocco) allowed us to study and quantify the effect of the lack of wastewater treatment on surface water quality in semi-arid hydrological context. The analysis is based on field data collected from June 2009 to December 2011. Concentration and load patterns of nitrogen, phosphorus and chromium (used in the processing of leather) are compared in stable hydrological conditions during low flow and high flow periods in an eight-location sampling ne...

  20. Iniquidade na assistência à gestação e ao parto em município do semiárido brasileiro Inequality in health care for women during gestation and delivery in a municipality in the semi-arid region of Brazil

    Directory of Open Access Journals (Sweden)

    Patrícia S Mano

    2011-12-01

    Full Text Available OBJETIVOS: avaliar a iniquidade na assistência à gestação e ao parto para menores de cinco anos residentes no município de Caracol, Piauí, Brasil. MÉTODOS: usando delineamento transversal, amostragem sistemática e aplicação de questionário domiciliar foram coletadas informações sobre características demográficas de mães e crianças, assistência à gestação e ao parto e nível socioeconômico. Por meio da técnica de componentes principais, criou-se um escore em tercis. As associações deste escore com as variáveis relativas à assistência à gestação e ao parto foram avaliadas pelos testes qui-quadrado e Kruskal- Wallis. RESULTADOS: todas as 405 crianças incluídas no estudo eram provenientes de famílias com renda inferior a um salário mínimo mensal; 65% residiam em área rural. Mães pertencentes ao maior tercil socioeconômico realizaram um maior número de consultas de pré-natal; realizaram maior número de exames de urina, hemograma, citopatológico de colo uterino e ultrassonografia, tiveram o parto realizado por médico e foram mais frequentemente submetidas à cesariana. CONCLUSÕES: mesmo entre os mais pobres, há enormes iniquidades em saúde. Combater os determinantes desta pobreza com programas sociais mais agressivos é imperativo, assim como priorizar o atendimento aos mais pobres dentre os pobres.OBJECTIVES: to evaluate inequality in health care during gestation and delivery for women with children under five years of age resident in the Municipality of Caracol, in the Brazilian State of Piauí. METHODS: a household questionnaire was applied to a cross-sectional systematic sample to collect data on the demographic characteristics of mothers and children, health care during pregnancy and deliver and socio-economic status. A tercile score was created using the principal component technique. The associations between this score and variables relating to health care for women during pregnancy and childbirth

  1. Leguminous species sequester more carbon than gramineous species in cultivated grasslands of a semi-arid area

    Science.gov (United States)

    Liu, Yu; Tian, Fuping; Jia, Pengyan; Zhang, Jingge; Hou, Fujiang; Wu, Gaolin

    2017-01-01

    The establishment of grasslands on abandoned cropland has been proposed as an effective method to mitigate climate change. In this study, five cultivated grasslands (three leguminous species and two gramineous species), one abandoned cropland, and one natural grassland were studied to examine how soil organic carbon (SOC) sequestration rate and sequestration efficiency change in a semi-arid area in China. Our results showed that leguminous grasslands had greater total biomass (above- and belowground biomass), SOC storage, SOC sequestration rate, and efficiency than gramineous grasslands, abandoned cropland, and natural grassland during the experimental period. The largest soil carbon (C) accumulation in leguminous grassland was mainly attributed to the capacity to incorporate C and the higher biomass production. Leguminous grasslands accumulated more SOC than gramineous grasslands by 0.64 Mg C ha-1 yr-1. The average SOC sequestration efficiency in leguminous grassland (1.00) was about 2 times greater than gramineous grassland (0.34). The results indicate that cultivated leguminous grassland sequestered more SOC with higher SOC sequestration efficiency than cultivated gramineous grassland in arid and semi-arid areas. Our results provide a reference for ecological management in arid and semi-arid areas.

  2. Multi-satellite sensor study on precipitation-induced emission pulses of NOx from soils in semi-arid ecosystems

    Science.gov (United States)

    Zörner, Jan; Penning de Vries, Marloes; Beirle, Steffen; Sihler, Holger; Veres, Patrick R.; Williams, Jonathan; Wagner, Thomas

    2016-07-01

    We present a top-down approach to infer and quantify rain-induced emission pulses of NOx ( ≡ NO + NO2), stemming from biotic emissions of NO from soils, from satellite-borne measurements of NO2. This is achieved by synchronizing time series at single grid pixels according to the first day of rain after a dry spell of prescribed duration. The full track of the temporal evolution several weeks before and after a rain pulse is retained with daily resolution. These are needed for a sophisticated background correction, which accounts for seasonal variations in the time series and allows for improved quantification of rain-induced soil emissions. The method is applied globally and provides constraints on pulsed soil emissions of NOx in regions where the NOx budget is seasonally dominated by soil emissions. We find strong peaks of enhanced NO2 vertical column densities (VCDs) induced by the first intense precipitation after prolonged droughts in many semi-arid regions of the world, in particular in the Sahel. Detailed investigations show that the rain-induced NO2 pulse detected by the OMI (Ozone Monitoring Instrument), GOME-2 and SCIAMACHY satellite instruments could not be explained by other sources, such as biomass burning or lightning, or by retrieval artefacts (e.g. due to clouds). For the Sahel region, absolute enhancements of the NO2 VCDs on the first day of rain based on OMI measurements 2007-2010 are on average 4 × 1014  molec cm-2 and exceed 1 × 1015  molec cm-2 for individual grid cells. Assuming a NOx lifetime of 4 h, this corresponds to soil NOx emissions in the range of 6 up to 65 ng N m-2 s-1, which is in good agreement with literature values. Apart from the clear first-day peak, NO2 VCDs are moderately enhanced (2 × 1014  molec cm-2) compared to the background over the following 2 weeks, suggesting potential further emissions during that period of about 3.3 ng N m-2 s-1. The pulsed emissions contribute about 21-44 % to total

  3. Avaliação da eficácia de taboa (Typha domingensis Pers. e batata-de-purga [Operculina hamiltonii (G. Don D.F. Austin & Staples] in natura sobre nematóides gastrintestinais de caprinos, naturalmente infectados, em clima semi-árido Evaluation of the effectiveness of "taboa" (Typha domingensis Pers. and "batata-de-purga" [Operculina hamiltonii (G. Don D.F. Austin & Staples] in natura on gastrointestinal nematodes of goats, naturally infected, in the semi-arid region

    Directory of Open Access Journals (Sweden)

    C.F. Silva

    2010-12-01

    Full Text Available Avaliou-se a eficácia da Typha domingensis (taboa e da Operculina hamiltonii (batata-de-purga in natura sobre nematóides gastrintestinais de caprinos, naturalmente infectados, em clima semi-árido. Foram utilizados 30 caprinos da raça Moxotó, e o rizoma da taboa e a raiz da batata-de-purga, avaliados através da fitoquímica. As fezes foram coletadas nos dias zero, sete e 25, após, o tratamento da contagem de OPG. Os animais foram distribuídos inteiramente ao acaso, com cinco tratamentos e seis repetições. Grupo I tratado com Moxidectina 0,2% em dose única de 0,5 mg Kg-1; o Grupo II tratado com Taboa na dose (10 g 20 Kg-1 peso vivo; Grupo III com batata-de-purga na dose de 9 g 20 Kg-1 p.v.; Grupo IV tratado com taboa 10 g 20 Kg-1 p.v. associada a batata 9 g 20 Kg-1 p.v. durante três dias consecutivos, todos administrados oralmente e o Grupo V como grupo controle. Os grupos tratados apresentaram redução no número médio de OPG aos 7 e 25 dias pós-tratamento, quando comparado com o grupo controle no respectivo período, sendo a batata-de-purga com maior redução aos 7 e a taboa aos 25 dias. A maior eficácia foi da batata-de-purga de 84% e 70%, nos dias 7 e 25 pós-tratamento. Verificou-se que a batata-de-purga foi eficaz no controle de nematóides gastrintestinais de caprinos no clima semi-árido e que a taboa associada com a batata tem potencial para serem utilizadas em programas alternativos de controle parasitário.The effectiveness of Typha domingensis ("taboa" and Operculina hamiltonii ("batata-de-purga" in natura was evaluated on gastrointestinal nematodes of goats, naturally infected, in the semi-arid region. Thirty Moxotó goats were used, and the rhizome of "taboa" and the root of "batata-de-purga" were analyzed through phytochemistry. Feces were collected on days zero, seven and 25 after the treatment for FECs. The distribution of animals was completely at random, with five treatments and six replicates. Group I was

  4. Implications of deep drainage through saline clay for groundwater recharge and sustainable cropping in a semi-arid catchment, Australia

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    W. A. Timms

    2011-11-01

    Full Text Available The magnitude and timing of deep drainage and salt leaching through clay soils is a critical issue for dryland agriculture in semi-arid regions (<500 mm yr−1 rainfall, such as parts of Australia's Murray-Darling Basin (MDB. In this unique study, hydrogeological measurements and estimations of the historic water balance of crops grown on overlying Grey Vertosols were combined to estimate the contribution of deep drainage below crop roots to recharge and salinization of shallow groundwater. Soil sampling at two sites on the alluvial flood plain of the Lower Namoi catchment revealed significant peaks in chloride concentrations at 0.8–1.2 m depth under perennial vegetation and at 2.0–2.5 m depth under continuous cropping indicating deep drainage and salt leaching since conversion to cropping. Total salt loads of 91–229 t ha−1 NaCl equivalent were measured for perennial vegetation and cropping, with salinity to ≥10 m depth that is not detected by shallow soil surveys. Groundwater salinity varied spatially from 910 to 2430 mS m−1 at 21 to 37 m depth (N = 5, whereas deeper groundwater was less saline (290 mS m−1 with use restricted to livestock and rural domestic supplies in this area. The Agricultural Production Systems Simulator (APSIM software package predicted deep drainage of 3.3–9.5 mm yr−1 (0.7–2.1% rainfall based on site records of grain yields, rainfall, salt leaching and soil properties. Predicted deep drainage was highly episodic, dependent on rainfall and antecedent, and over a 39 yr period was restricted mainly to the record wet winter of 1998. During the study period, groundwater levels were unresponsive to major rainfall events (70 and 190 mm total, and most piezometers at about 18 m depth remained dry. In this area, at this time, recharge negligible due to low rainfall and large potential evapotranspiration, transient hydrological conditionsafter changes

  5. Implications of deep drainage through saline clay for groundwater recharge and sustainable cropping in a semi-arid catchment, Australia

    Directory of Open Access Journals (Sweden)

    W. A. Timms

    2012-04-01

    Full Text Available The magnitude and timing of deep drainage and salt leaching through clay soils is a critical issue for dryland agriculture in semi-arid regions (<500 mm yr−1 rainfall, potential evapotranspiration >2000 mm yr−1 such as parts of Australia's Murray-Darling Basin (MDB. In this rare study, hydrogeological measurements and estimations of the historic water balance of crops grown on overlying Grey Vertosols were combined to estimate the contribution of deep drainage below crop roots to recharge and salinization of shallow groundwater. Soil sampling at two sites on the alluvial flood plain of the Lower Namoi catchment revealed significant peaks in chloride concentrations at 0.8–1.2 m depth under perennial vegetation and at 2.0–2.5 m depth under continuous cropping indicating deep drainage and salt leaching since conversion to cropping. Total salt loads of 91–229 t ha−1 NaCl equivalent were measured for perennial vegetation and cropping, with salinity to ≥ 10 m depth that was not detected by shallow soil surveys. Groundwater salinity varied spatially from 910 to 2430 mS m−1 at 21 to 37 m depth (N = 5, whereas deeper groundwater was less saline (290 mS m−1 with use restricted to livestock and rural domestic supplies in this area. The Agricultural Production Systems Simulator (APSIM software package predicted deep drainage of 3.3–9.5 mm yr−1 (0.7–2.1% rainfall based on site records of grain yields, rainfall, salt leaching and soil properties. Predicted deep drainage was highly episodic, dependent on rainfall and antecedent soil water content, and over a 39 yr period was restricted mainly to the record wet winter of 1998. During the study period, groundwater levels were unresponsive to major rainfall events (70 and 190 mm total, and most piezometers at about 18 m depth remained dry. In this area, at this time, recharge appears to be negligible due to low

  6. Sahra integrated modeling approach to address water resources management in semi-arid river basins

    Energy Technology Data Exchange (ETDEWEB)

    Springer, E. P.; Gupta, Hoshin V. (Hoshin Vijai),; Brookshire, David S.; Liu, Y. (Yuqiong)

    2004-01-01

    Water resources decisions in the 21Sf Century that will affect allocation of water for economic and environmental will rely on simulations from integrated models of river basins. These models w