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McCool, Jon-Paul. "Paleoenvironmental Approaches in Arid Geoarchaeology: Assessment of Former Habitation Zones and Landscapes." University of Cincinnati / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1522057729882415.
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Hempson, Gareth Peter. "Herbivore dynamics in an arid environment." Thesis, University of Edinburgh, 2011. http://hdl.handle.net/1842/5665.
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This study investigated the effects of a seasonally variable forage resource on herbivore population dynamics. This involved estimating the relative importance of environmental conditions, and the accessible and used forage resources, at different stages of the seasonal cycle to herbivores in different life-stages and at different points in the reproductive cycle. This study was carried out in the Richtersveld region in South Africa, using goats kept by semi-nomadic Nama pastoralists. In the main study site, the Richtersveld National Park (RNP), herd movements follow a general seasonal migratory pattern: herds are based in the riparian zone of the Orange River during the dry season, and on plains away from the river in the wet season. Over 800 uniquely marked female goats in three life-stages (adults, yearlings and kids) were monitored over a three year period (2007 to 2009). These goats were weighed at 2 - 3 month intervals to provide an estimate of body condition. Browse availability in the riparian zone was estimated using measurements at an individual branch-level and a whole tree-level. FPAR satellite imagery was used to estimate forage abundance outside the riparian zone. Goat density was mapped for each week of the study using census data and the herd positions. Goat body condition, survival rates and fecundity rates for each life-stage were modelled as a response to forage availability, density and climatic conditions. The riparian zone in the RNP was found to function as the key resource of the RNP goat population. Forage depletion by goat browsing resulted in a negative feedback on goat body condition. This decline in body condition was directly related to lower adult survival over the dry season. Fecundity was also most influenced by dry season conditions through the negative effect of poor body condition on pregnancy rates and birth rates. Asymmetric competition between life-stages, resulting from the riparian browse profile being depleted from the bottom-up, was predicted to have a strong effect on goat demography by contributing to differences in body condition and survival rates between life-stages. Wet season conditions appeared to have little effect on goat population dynamics, either through increased neonate survival or through a mass carry-over effect influencing dry season survival. Goat body condition and vital rates were compared between the RNP and the neighbouring Kuboes rangeland, which does not have access to the Orange River, to assess the impact of differences in their dry season forage resource. The long-term size and variability of the livestock population in the RNP was also compared with livestock dynamics in Paulshoek, a rangeland 250 km south east of the RNP. The a priori predictions of relative population dynamics in each region, based on perceived differences in the nature of the key resource in each region, were largely supported.
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Aralova, Dildora, Kristina Toderich, Ben Jarihani, Dilshod Gafurov, Liliya Gismatulina, Babatunde A. Osunmadewa, and Abualgasim Majdaldin Rahamtallah. "Environmental resilience of rangeland ecosystems: Assessment drought indices and vegetation trends on arid and semi-arid zones of Central Asia." SPIE, 2016. https://tud.qucosa.de/id/qucosa%3A35118.
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The Central Asian (CA) rangelands is a part of the arid and semi-arid ecological zones and spatial extent of drylands in CA (Tajikistan, Kazakhstan, Uzbekistan, Kyrgyzstan, and Turkmenistan) is vast. Projections averaged across a suite of climate models, as measured between 1950-2012 by Standardised Precipitation-Evapotranspiration Index (SPEI) estimated a progressively increasing drought risks across rangelands (Turkmenistan, Tajikistan and Uzbekistan) especially during late summer and autumn periods, another index: Potential Evapotranspiration (PET) indicated drought anomalies for Turkmenistan and partly in Uzbekistan (between 1950-2000). On this study, we have combined a several datasets of drought indices ( SPIE, PET, temperature_ToC and precipitation_P) for better estimation of resilience/non-resilience of the ecosystems after warming the temperature in the following five countries, meanwhile, warming of climate causing of increasing rating of degradations and extension of desertification in the lowland and foothill zones of the landscape and consequently surrounding experienced of a raising balance of evapotranspiration (ET0). The study concluded, increasing drought anomalies which is closely related with raising (ET0) in the lowland and foothill zones of CA indicated on decreasing of NDVI indices with occurred sandy and loamy soils it will resulting a loss of vegetation diversity (endangered species) and raising of wind speeds in lowlands of CA, but on regional level especially towards agricultural intensification (without rotation) it indicated no changes of greenness index. It was investigated to better interpret how vegetation feedback modifies the sensitivity of drought indices associated with raising tendency of air temperature and changes of cold and hot year seasons length in the territory of CA.
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Duncan, Corrine. "Seeds, soils and moisture : ecophysiology to inform mine site restoration in arid zones." Thesis, Federation University Australia, 2019. http://researchonline.federation.edu.au/vital/access/HandleResolver/1959.17/180639.
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Mining in arid regions of Australia is followed by restoration and rehabilitation efforts. However, attempts to reintroduce many woody plant species have been unsuccessful. Water is the key limiting resource to plant growth and seed germination in arid zones. In this thesis, I investigated ecophysiological processes that may help improve recruitment across novel arid landscapes. I tested seed traits and dormancy cues of eight keystone plants and found that six of them had non-dormant, rapidly germinating seeds; a trait we propose is an adaptation to the region’s unpredictable rainfall. To identify the germination niche of species, I incubated seeds under different temperatures and water potentials, and found drought avoidance to be an important survival strategy for arid species. I collected soil samples to compare biophysicochemical properties of reconstructed soils to remnant ecosystems, and found that the distribution of clay content in the reconstructed soils did not mirror the remnant soils, compromising their ability to sustain perennial vegetation. I also monitored soil moisture and found that soil reconstruction reduces rainfall infiltration and retention, and subsequently increases evaporation. The synthesis of these results demonstrate some of the limitations to successful restoration in these systems, such as (1) unknown dormancy cues and poor seed longevity, (2) infrequent and episodic plant recruitment due to water limitation, and (3) reduced hydrological function of reconstructed soils. The failure to reinstate hydrological function is the major constraint to ecological restoration in this arid zone. Nonetheless, results from this study suggest that restoration is possible through more strategic use of seed, careful selection of drought tolerant species, and increasing soil moisture. Further failures to reinstate ecosystem function and community dynamics in arid zones with reconstructed soils can be prevented by understanding the edaphic constraints to plant establishment, and ameliorating conditions to mimic ecohydrological processes in remnant ecosystems.Doctor of Philosophy
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Rehman, Abdul [Verfasser]. "Epidemiology of Ticks and Tick-borne Pathogens in the Semi-arid and the Arid Agro-ecological Zones in Pakistan / Abdul Rehman." Berlin : Freie Universität Berlin, 2017. http://d-nb.info/1123998809/34.
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Mohammed, R. "Assessment of the effect of climate change in anticipated water resources availability in arid climate zones." Thesis, University of Salford, 2017. http://usir.salford.ac.uk/44643/.
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Climate change impact and drought phenomena linked with anthropogenic pressure have become a growing concern for water resource managers and policy makers, particularly in arid and semi-arid regions. This research proposes generic methodologies to evaluate the prospective impact of such changes at a basin-scale. The Lower Zab River Basin, northern Iraq, has been selected as a representative case study. These methodologies have been achieved through the following: (1) Highlight the impact of potential evapotranspiration (PET) methods, elevation, and climatic conditions on the reconnaissance drought index (RDI) results, applying three of the most widespread PET estimates, which are Thornthwaite, Hargreaves, and Blaney-Criddle in addition to the Food and Agriculture Organization Penman-Monteith reference technique, using data from 24 stations cover different elevations and climatic conditions for the period from 1979 to 2014. The initial form of RDI is directly influenced by the selected PET method at different elevations for all regions. (2) Combine the results of the flow duration curve and the digital filtering algorithms to overcome the limitations of the traditional baseflow separation methods, and then determine the baseflow annual variations. The water yielded from the basin storage system during the dry seasons resulted in dissimilarities in the observed baseflow index between the pre-damming and post-damming periods of the streamflow. (3) Quantify the hydrological alterations of various flow characteristics utilise the Indicators of Hydrologic Alteration method, in addition to multi- regression, hydrologic sensitivity, and hydrologic model simulations. Climate change was the main factor reducing streamflow. (4) Compare the results of seven ensembles General Circulation Models (GCM) with the results of delta perturbation (DP) scenarios. Both scenarios predicted almost identical decreases in the mean monthly flows to the reservoir. The DP scenarios allow the sensitivity of the impact models to climate change to be more evidently determined compared to GCM scenarios so that they could be complemented GCM scenarios.
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Heshmatti, Gholam Ali. "Plant and soil indicators for detecting zones around water points in arid perennial chenopod shrublands of South Australia /." Title page, contents and summary only, 1997. http://web4.library.adelaide.edu.au/theses/09PH/09phh584.pdf.
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Thesis (Ph. D.)--University of Adelaide, Dept. of Botany, 1997.Errata page is behind title page (p. i). Copies of author's previously published articles inserted. Includes bibliographical references (leaves 121-156).
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Lima, Géssica Silva [UNESP]. "Caracterização físico-hídrica do solo do perímetro irrigado pontal sul por funções de pedotransferência." Universidade Estadual Paulista (UNESP), 2016. http://hdl.handle.net/11449/144725.
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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)
A busca por meios que auxiliem a eficiência no uso dos recursos hídricos e conservação do solo é indispensável para a sustentabilidade da atividade agrícola na região semiárida brasileira. Assim sendo, estudos capazes de indicar e orientar medidas que viabilizem a produção de alimentos com maior eficiência no uso da água e auxiliem as políticas de gestão e planejamento dos recursos hídricos, são de grande relevância. Entre as ferramentas existentes que podem auxiliar no planejamento e no manejo do uso da água na agricultura, podemos citar o uso da geoestatística, análise de agrupamento e funções de pedotransferência. Assim, o objetivo deste trabalho foi realizar a caracterização da área do Perímetro Irrigado Pontal Sul, em Petrolina – PE. As análises e resultados estão divididos em três capítulos. O primeiro apresenta as zonas homogêneas dos atributos físicos do solo e da velocidade de infiltração básica da água no solo, obtidas por meio de análise geoestatística e análise multivariada de agrupamento fuzzy c-means. No segundo capítulo, foram desenvolvidas funções de pedotransferência (FPT) para estimativa dos teores de água do solo na capacidade de campo (CC), ponto de murcha permanente (PMP) e água disponível no solo (AD), utilizando técnicas de regressão múltipla, a partir dos dados de granulometria e densidade do solo. No terceiro capítulo, realizou-se o estudo da variabilidade espacial da umidade do solo por meio da geoestatística, utilizando dados observados e estimados por FPT para as umidades na CC, PMP e AD. Concluiu-se que é possível um zoneamento com menor quantidade de variáveis para auxílio no planejamento do uso de água no perímetro irrigado. Houve diferença significativa para todos os atributos entre as 3 zonas homogêneas geradas. A maioria das FPT desenvolvidas não apresentaram boa acurácia para estimar o teor de água no solo. Entre elas, os melhores desempenhos foram observados para estimativa da CC e PMP no banco de dados geral na camada de 0,0-0,20 m. Na análise geoestatística os parâmetros dos semivariogramas ajustados para o banco de dados medidos e banco de dados estimados, quando comparados, apresentaram menor variação para a camada de solo de 0-0,2 m.
The search for tools to assist the efficient use and conservation of water and soilresources is essential for sustainability of agriculture in the Brazilian semiarid region. Thus, studies to indicate and guide procedures that enable the production of food with greater efficiency about water use and assist management policies and planning of water resources, have great importance. Among the existing tools that can assist in the planning and management of water use in agriculture, we have the geostatistics, multivariated analysis and pedotransfer functions. Hence, the objective of this study was to describe the area of the Pontal Sul Irrigation Scheme, in Petrolina, state of Pernambuco, Brazil. The analysis and results are divided into three chapters. The first chapter presents homogeneous zones obtained by using geostatistical analysis and multivariate analysis of fuzzy c-means clustering of soil physical attributes and soil water infiltration rate. In the second chapter pedotransfer functions were developed (PTF) to estimate soil water content at field capacity (FC), wilting point (WP) and available soil water (AW), using multiple regression techniques, based on data of soil particle size and soil density. The third chapter presents the study of the spatial variability of soil moisture by using geostatistics with observed and estimated by PTF data for soil water content at FC, WP and AW. It was concluded that it is possible a zoning with fewer variables to aid in the planning of water use in the irrigation scheme area. All attributes presented significant differences among the three homogeneous zones delimited. Most of the PTF developed did not show good accuracy to estimate the soil water content. Among them, the best performances were observed to estimate the FC and WP in the overall database in the soil layer of 0-0.2 m. In the geostatistical analysis the parameters of the semivariograms adjusted for the database measured and for the estimated database, when compared, presented smaller variation for the soil layer of 00,2 m.
CNPq: 142174/2013-0
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Rodríguez-Ferraro, Adriana. "Community ecology and phylogeography of bird assemblages in arid zones of northern Venezuela implications for the conservation of restricted-range birds /." Diss., St. Louis, Mo. : University of Missouri--St. Louis, 2008. http://etd.umsl.edu/r3141.
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Porto, Everaldo Rocha 1948. "An economic evaluation of selected soil and water management technologies for rainfed agriculture : a study case in the arid zones of Brazil." Diss., The University of Arizona, 1988. http://hdl.handle.net/10150/191134.
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Water harvesting techniques were used for increasing water availability for rainfed agriculture and for human consumption. The treatments involving soil and water management for cropping were as follows: (1) traditional; (2) microcatchment; (3) microcatchment plus fertilization with ordinary superphosphate (OSP); (4) microcatchment plus fertilization with manure; and (5) supplemental tank irrigation. A cistern with 50 m³ capacity was constructed to provide drinking water. The crop enterprises were cowpeas (Vigna unguiculata)/corn (Zea mays), and sorghum (Sorghum bicolor)/cactus (Opuntia spp.)/algaroba (Prosopis juliflora). Both were intercropped. The overall objectives of the study were: (1) to examine the impact of the application of water harvesting techniques together with crop management, with and 14 without fertilization on: farmer, (ii) profitability cropping, and (iii) labor benefit of a cistern based (i) financial position of the of each individual enterprise in utilization; (2) to estimate the on the costs of carrying water. All analysis were developed with the aid of Supercalc 4 spreadsheet software. Farm performance measures were: crop production; cash flows; income statements, net worth; cost and returns statements; and labor utilization. The impact of the household cistern was assessed through a benefit cost approach. From the results the following main conclusions were drawn: (1) microcatchment contributed marginally to increased yields; (2) microcatchment combined with OSP produced yield increases which were twice those of the traditional process; (3) tank irrigation with OSP quadrupled the traditional productivities; (4) the sorghum/cactus/algaroba enterprise presented a better cash position than cowpeas/ corn; (5) the farm can support the investments necessary for the application of water harvesting since it is financially liquid and solvent; (6) significant increase in net income was achieved when water harvesting was combined with fertilization for both enterprises; (7) the existing family labor potential on the farm is enough to supply the demand imposed by any one of the soil and water management treatment; (8) if opportunity cost of labor is involved in assessing the profitability of cropping, the most profitable soil and water management practice was tank irrigation; and (9) the construction of a cistern is an economical and feasible decision.
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Baird, Douglas. "Neolithic chipped stone assemblages from the Azraq Basin, Jordan, and the significance of the Neolithic of the arid zones of the southern Levant." Thesis, University of Edinburgh, 1993. http://hdl.handle.net/1842/19860.
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Amogne, Firew Tegegne. "Evaluation of alternative feed resources for ruminants under arid zones of the tropics and sub-tropics: the case of cactus pear (Opuntia ficus-indica) in Ethiopia /." Berlin : Köster, 2007. http://bvbr.bib-bvb.de:8991/F?func=service&doc_library=BVB01&doc_number=015824295&line_number=0001&func_code=DB_RECORDS&service_type=MEDIA.
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Locquin-Linard, Monique. "1) etude de la mycoflore coprophile des zones arides et semi-arides du nord de l'afrique : 2) etude de l'amyloeidicite des "huelle cells" chez les emericella (ascomycetes)." Paris 6, 1988. http://www.theses.fr/1988PA066682.
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310 especes de champignons appartenant a 121 genres representant les myxomycetes, zygomycetes, ascomycetes et deuteromycetes, ont ete repertories au cours d'une etude portant sur 213 recoltes de feces collectes dans les zones desertiques africaines. Un inventaire commente est donne
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Fetoui, Mondher. "Évaluer et suivre la désertification en zones arides tunisiennes pour accompagner l'aide à la décision : dynamiques interactives "Climat-Homme-Espace-Ressources naturelles" via les paysages." Thesis, Montpellier 3, 2011. http://www.theses.fr/2011MON30007/document.
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La difficulté à comprendre la désertification dans les zones arides tunisiennes se manifeste dans les interactions complexes entre les dynamiques socioéconomiques et biophysiques à différentes échelles spatiales et temporelles. L’apport de ce travail réside tant dans les avancées sur la compréhension des causes et processus, que dans la proposition d’approches systémiques (climat-homme-espace-ressources : système CHER), géographiques (paysage) et multi-acteurs, associées à des méthodes (modèles et outils) reproductibles, pour l’évaluation et le suivi (indicateurs) des risques de désertification, en lien avec leurs déterminants interactifs, à une échelle territoriale. Le paysage, en tant que source d’information et instrument, est au cœur de ce travail. Ce dernier a conduit à i) la construction des modèles explicatifs CHER déclinés par type paysager (issue d’une lecture multidisciplinaire et de la caractérisation des paysages), ii) l’élaboration des indices de risque de désertification (par intégration spatiale des fonctionnements biophysiques et socioéconomiques et à travers la modélisation), iii) la compréhension et la comparaison entre types paysagers des risques et de la part respective prise par les causes socioéconomiques et biophysiques, et iv) la proposition de trois nouvelles approches/méthodes/outils visant à mieux évaluer les actions de lutte déjà mises en œuvre, cibler les futures actions et suivre la désertification. Les résultats ont tous été élaborés dans l’interdisciplinarité et avec la mobilisation des acteurs/décideurs de la gestion durable des territoires pour augmenter leur utilité dans les programmes de lutte contre la désertification, pour valoriser les observatoires de l’environnement et leur donner un rôle d’appui aux politiques publiquesThe difficulty in understanding desertification in the Tunisian arid zones manifested in the complex interactions between socioeconomic and biophysical dynamics at different spatial and temporal scales. This work contribute on advanced understanding of the causes and processes and propose a systemic (climate-human-space-resource: CHER), geographical (landscape) and multi-actors approaches associated with methods (models and tools) reproducible for the assessment and monitoring (indicators) of risk of desertification, according to its interactive determinants on a territory scale. The landscape, as a source of information and the tool, is at the core of this work which led to i) the construction of explanatory models broken down by type of landscape (based on multidisciplinary characterization of landscapes), ii) the development of indexes of desertification risk (based on spatial integration of biophysical and socio-economic functioning through modeling), iii) the understanding and comparison of risks and their respective causes in the landscape types, and iv) the proposal of three new approaches / methods / tools to better assess the actions already implemented to combat desertification, to better target future actions and to better monitor desertification. The results have all been developed in interdisciplinarity and involve the mobilization of actors / decision makers in the sustainable management of territories to increase their usefulness in programs to combat desertification, to value environmental observatories and give them a role to support public policies
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Gibson, Michelle Rene. "Movement ecology of Australian arid-zone birds." Thesis, Durham University, 2018. http://etheses.dur.ac.uk/12778/.
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The movements of nomadic species are poorly understood, being highly dynamic over time and space. There is an urgent need to better understand this group as current conservation approaches appear not to be providing adequate protection. In this thesis, I evaluate a survey method to monitor this dynamic group, assess environmental variables driving their movements over time, and explore how rainfall structures the overall avian community. To date, no standardized, large-scale monitoring has been carried out for arid zone or nomadic species. In Chapter 2, I describe a protocol for surveying this group over five years using two survey methods. Detection probabilities and robust density estimates were generated for 64 species and showed the majority fluctuated markedly over time. Line transect surveys were more effective for species richness and abundance measures. This survey method provides the first standardized density estimates for this assemblage and can be easily repeated in future for this and other remote, arid biological communities. The movement characteristics of species with unpredictable, aseasonal movements are very poorly understood and difficult to measure. In Chapter 3, I develop a method for quantifying extent of bird movement by analysing changes in species’ site persistence and variability in inter-annual densities over time, and compare results with existing movement classifications. Continuous variation in extent of species movement indicated that a binary grouping of resident versus nomadic species is inappropriate. Existing movement classifications likely underestimate species movements within arid regions of their distribution, suggesting that caution is needed when using sweeping species-level classifications, especially for Australian birds whose movements can be heavily environment-dependent. Unlike regular migration, which is triggered by seasonal cues such as day length and temperature, movement in nomads is thought to be triggered by less predictable environmental conditions. In Chapter 4, I explore the relative influence of dynamic and static environmental variables on species abundance. Dynamic variables were more important for nomadic versus resident species but static variables were equally important for nomadic and resident species. These findings suggest that habitat structure is important to consider in addition to dynamic environmental features for understanding nomadic species movements. Pulse events are thought to be positively correlated with nomadic species movements and to play an important role in structuring arid biological communities. In Chapter 5, I investigate how structural changes observed in Australia’s arid bird community relate to rainfall and vegetation greenness. The importance of rainfall was mediated through vegetation growth and the community is dynamic at a local level but exhibits stability at a landscape level, underscoring the importance of connectivity between suitable habitats within this landscape to enable species to reshuffle among sites. In sum, my thesis highlights the importance of standardized data for enabling an empirical approach to understanding nomadic and arid-zone bird species. Findings will advance our understanding of these species’ dynamics and lay groundwork for improving protection of this group by identifying further research priorities.
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Gunawardene, Nihara. "Arid zone ant communities of Western Australia." Thesis, Curtin University, 2003. http://hdl.handle.net/20.500.11937/1178.
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This thesis is prepared in three parts; the first part is a study of the ant species of the southern Carnarvon Basin, which was undertaken in order to determine the patterns of ant species distribution in this arid zone area. The distribution patterns were looked at in terms of biogeographical regions and they demonstrated the transitional nature of this particular area. Recommendations to alter the border between the South-west Province and the Eremaean Province were supported. The next chapter of this thesis analysed ant species from long unburnt and burnt areas of three main vegetation types (two Triodia species grasslands and Acacia aneura woodlands) in the Gibson Desert Nature Reserve. This study was carried out to observe the recovery of ant populations after fire. The results provided further evidence that invertebrates are measurably impacted by fire in the arid zone. The final chapter is a comparison of these two arid zone studies with six other ant community studies from throughout Western Australia. It demonstrated the uniqueness of some arid zone sites as well as related each study to each other according to their ant communities.
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Gunawardene, Nihara. "Arid zone ant communities of Western Australia." Curtin University of Technology, Department of Environmental Biology, 2003. http://espace.library.curtin.edu.au:80/R/?func=dbin-jump-full&object_id=16212.
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This thesis is prepared in three parts; the first part is a study of the ant species of the southern Carnarvon Basin, which was undertaken in order to determine the patterns of ant species distribution in this arid zone area. The distribution patterns were looked at in terms of biogeographical regions and they demonstrated the transitional nature of this particular area. Recommendations to alter the border between the South-west Province and the Eremaean Province were supported. The next chapter of this thesis analysed ant species from long unburnt and burnt areas of three main vegetation types (two Triodia species grasslands and Acacia aneura woodlands) in the Gibson Desert Nature Reserve. This study was carried out to observe the recovery of ant populations after fire. The results provided further evidence that invertebrates are measurably impacted by fire in the arid zone. The final chapter is a comparison of these two arid zone studies with six other ant community studies from throughout Western Australia. It demonstrated the uniqueness of some arid zone sites as well as related each study to each other according to their ant communities.
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McGee, P. A. "Role of mycorrhizas in the regeneration of arid zone plants /." Title page, contents and summary only, 1987. http://web4.library.adelaide.edu.au/theses/09PH/09phm1448.pdf.
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Lictevout, Elisabeth. "Accès à l'eau souterraine des populations vulnérables en zone aride : un problème de ressource, de gestion ou d'information ?" Thesis, Montpellier, 2018. http://www.theses.fr/2018MONTG059/document.
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Les zones arides abritent 35% de la population mondiale et affichent parmi les plus hauts niveaux de pauvreté. La faible quantité et l’hétérogénéité spatio-temporelle des précipitations et des écoulements compliquent non seulement l’exploitation de la ressource mais aussi la compréhension de ces hydro-systèmes. Cependant, depuis les origines de l’histoire humaine, les populations ont su domestiquer l’eau des zones arides, tant superficielle, que souterraine. Mais les dernières décennies ont vu certaines zones arides devenir le théâtre du développement d’activités industrielles aux usages d’eau intensifs qui posent des problèmes de gestion et d’accès à l’eau des usagers, en particulier des populations vulnérables. Dans le nord du Chili, le Désert d’Atacama est l’une des zones les plus arides au monde. Depuis les années 90, avec l'installation de grands projets miniers, la région a connu une croissance démographique et économique constante. L’eau souterraine y est intensivement utilisée pour les activités minières, l’approvisionnement des populations et l’agriculture. Afin de comprendre si les problèmes d’accès à l’eau souterraine de l’aquifère Pampa del Tamarugal, région de Tarapacá, sont dus au fait que la ressource est limitée, que la gestion des eaux souterraines doit être améliorée, ou encore à un manque d’information scientifique sur cette ressource, une approche multi et interdisciplinaire a été mise en place. Cette approche est constituée de deux grandes parties : d’une part, la caractérisation des ressources en eau souterraines de l’aquifère Pampa del Tamarugal. Pour cela, les données brutes existantes et leurs conditions de production ont été analysées et un nouveau réseau hydrométrique a été conçu grace à l’analyse multicritère couplée à une analyse SIG. Ensuite, la réalisation d’une carte piézométrique actualisée et la comparaison de cette carte avec les données piézométriques des dernières décennies ont permis de comprendre l’évolution de l’aquifère. L’étude géologique détaillée et l’analyse hydrochimique et isotopiques de sources et forages a permis de caractériser la recharge de l’aquifère, entre autres de définir le rôle prépondérant du substratum mésozoïque sur les écoulements notamment dans la couverture cénozoïque. Pour pallier au manque de données historiques, une approche complémentaire a été mise en place consistant en l’intégration des connaissances des populations locales indigènes pour l’élaboration du modèle hydrogéologique conceptuel. D’autre part, la gestion des ressources en eaux souterraines de l'aquifère Pampa del Tamarugal a été analysée, en s’attachant notamment à comprendre le rôle de l’information scientifique et technique et les stratégies et discours des acteurs sur cette gestion et sur les usages. Finalement, l’étude d’un système ancestral de gestion de l’eau a permis de générer l’information nécessaire à sa préservation en tant que patrimoine hydraulique de zone aride mais également à sa réutilisation pour la gestion actuelle de l’aquifère. Ces travaux de recherche ont permis d’améliorer la compréhension des mécanismes de recharge, ainsi que des écoulements et de l’évolution de la ressource en eaux souterraines sous pression anthropique dans une zone aride et montagneuse telle que le nord du Chili. Ils ont aussi permis de préciser les contraintes limitant l’accès à l’eau des populations vulnérables dans la zone d’étude, et le rôle de l’information scientifique dans la gestion de la ressource en eaux souterrainesDrylands are home to 35% of the world's population and have among the highest levels of poverty. The small quantity and spatio-temporal heterogeneity of rainfall and runoff complicate not only the exploitation of the resource but also the understanding of those hydro-systems. However, since the origins of human history, in arid areas, people have been able to domesticate both surface and ground water the water. But the last decades have seen some arid areas become the scene of the development of industrial activities with intensive water uses that pose problems of management and access to water for users, particularly vulnerable populations. In the north of Chile, the Atacama Desert is one of the most arid areas of the world. Since the 1990s, with the installation of major mining projects, the region has experienced constant demographic and economic growth. Groundwater is extensively used for mining, domestic supply and agriculture. In order to understand if the problems of access to the groundwater of the Pampa del Tamarugal aquifer, in the Tarapacá region, are due to a limited resource, management issues, or to a lack of scientific information, a multi-disciplinary and interdisciplinary approach has been put in place. This approach consists of two main parts: first, the characterization of the groundwater resources of the Pampa del Tamarugal aquifer. For this, the existing raw data and their production conditions have been analysed and a new hydrometric network has been designed with a multi-criteria analysis coupled with a GIS analysis. Then, the realization of an updated piezometric map and the comparison of this map with the piezometric data of the last decades allow to understand the evolution of the aquifer. Based on a detailed geological study and hydrochemical and isotopic analysis of sources and boreholes, the recharge of the aquifer has been characterized with the preponderant role of the Mesozoic substratum on the flows especially in the Cenozoic cover. To compensate for the lack of historical data, a complementary approach has been put in place consisting of integrating the local and indigenous knowledge for the development of the conceptual hydrogeological model. On the other hand, the management of the groundwater resources of the Pampa del Tamarugal aquifer was analyzed, with particular attention to understanding the role of scientific and technical information and the strategies and discourses of the actors on this management and on uses. Finally, the study of an ancient water management system has generated the information necessary for its preservation as a water heritage an arid zone but also in order to reuse this system for the current management of the aquifer. This research has improved the understanding of the Pampa del Tamarugal recharge mechanisms, as well as the flow and evolution of groundwater resources under anthropogenic pressure in an arid and mountainous area such as northern Chile. They also clarified the constraints limiting access to water for vulnerable populations in the study area, and the role of scientific information in the management of groundwater resources
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Bourhane, Zeina. "Anthropogenic impacts on microbial communities in agriculture aride zones." Electronic Thesis or Diss., Pau, 2021. http://www.theses.fr/2021PAUU3071.
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Les milieux aquatiques et ses alentours, dans les régions arides et semi-arides, sont soumis à une forte pression anthropique provenant des activités agricoles et industrielles. Ces zones uniques sont caractérisées par une salinité naturelle et des fluctuations saisonnières drastiques. Cette thèse apporte des informations pour mieux comprendre les facteurs qui influencent les assemblages des communautés microbiennes et leurs adaptations aux polluants dans des conditions environnementales extrêmes, informations permettant de définir des bioindicateurs potentiels. Ces bioindicateurs microbiens constituent des outils prometteurs pour la surveillance environnementale en évaluant le statut écologique et la santé des écosystèmes. Ainsi, ce travail de thèse a pour but de déchiffrer les règles qui affectent les assemblages des communautés microbiennes habitant les sols et les sédiments des zones arides et semi-arides. Nous avons étudié les communautés microbiennes autour du lac Ichkeul (Tunisie) et des "Saladas de Bujaraloz-Sástago" (Salineta, Monegros, Espagne), deux écosystèmes aquatiques emblématiques RAMSAR. Nous avons combiné des approches métagénomiques basées sur le séquençage des gènes 16S rRNA, des analyses chimiques et des indices microbiens pour déterminer les relations entre la composition microbienne et les paramètres environnementaux. Nous avons identifié l'impacts des polluants, tels que les hydrocarbures, les pesticides et les métaux lourds, sur les communautés microbiennes des sols et des sédiments et caractérisé la dynamique des communautés microbiennes en fonction des variations saisonnières. Nous avons défini des bio-indicateurs microbiens pertinents, identifié des taxons microbiens spécialistes particulièrement adaptés aux conditions environnementales, en particulier à la salinité naturelle. Enfin, cette étude ouvre de nouvelles perspectives pour le développement des outils de bio-surveillance, nécessaires pour la gestion et la restauration des écosystèmes aquatiquesAquatic environments and their surroundings in arid and semi-arid regions are subjected to strong anthropogenic pressure resulting from agriculture and industrial activities. These unique areas are characterized by natural salinity and drastic seasonal fluctuations. The thesis provides information to better understand the factors shaping the microbial communities assemblages and their adaptation to pollutants under extreme environmental conditions, in order to examine the possibility to define microbial bioindicators. Such microbial bioindicators constitute promising tools for a careful environmental monitoring, which is required to evaluate the ecological status and environmental health of ecosystems in arid and semi-arid regions. In order to decipher the rules governing the assemblages of microbial communities inhabiting soils and sediments in arid and semi-arid zones, we investigated microbial communities around the Ichkeul Lake (Tunisia) and the “Saladas de Bujaraloz-Sástago” (Salineta, Monegros, Spain), two emblematic aquatic RAMSAR ecosystems. Metagenomic approaches, chemical analyses and integrative microbial indexes were combined to determine the relationships between microbial composition and environmental parameters. We identified the impacts of pollutants such as hydrocarbons, pesticides and heavy metals on microbial communities in soils and sediments and characterized microbial community dynamics according to seasonal variations. We defined relevant microbial bioindicators adapted, identified microbial specialists adapted to the environmental conditions, particularly to natural salinity. Finally, this study provides new insight for developing biomonitoring tools, requested for the management and restoration of aquatic ecosystems
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Saccò, Mattia. "Functional ecology of calcrete aquifers in arid zone Western Australia." Thesis, Curtin University, 2020. http://hdl.handle.net/20.500.11937/80356.
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This study investigates the ecology of an arid zone calcrete through an interdisciplinary design composed of multivariate analyses, hydrology, isotopic ecology and genetics. Our results indicate that the biotic community (microbes and stygofauna) is closely linked to the hydrodynamic conditions influenced by different rainfall regimes. The inflow of rainfall triggered shifts towards more deterministic dynamics, revealing a complex web of interactions. This investigation provides crucial untangling of the ecological dynamics regulating biotic communities in groundwaters.
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Pistorius, Penny. "How air temperature affects flight initiation distance in arid-zone birds." Master's thesis, University of Cape Town, 2016. http://hdl.handle.net/11427/20993.
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Arid zones, such as the Kalahari in southern Africa, are experiencing an increase in the number of hot days, as well as in the intensity of heat waves. Research is being conducted to try and understand how increasing temperatures will impact bird communities and population persistence in these areas. Understanding the mechanisms through which birds are vulnerable to climate change is key to answering these questions. This study investigated how changes in air temperature affect arid-zone birds' response to predators. The flight initiation distances (FID), i.e. the distance from a predator when the prey initiates escape, of eight bird species in the Kalahari were measured over a range of air temperatures during October and November 2015. The results from this study show a negative relationship between air temperature and FID. This relationship was weak across the full range of temperatures observed during the study period (11.9 ⁰C - 40.4 ⁰C), with a large amount of variability in FID not explained by air temperature. However, high air temperatures (> 35 ⁰C) were important in explaining some of the variation in FID. Starting distance, time of day, bird species, plant species, bird location (on the ground / in the canopy / at the top of the tree / in a dead tree), bird exposure (whether the bird was in the sun or in the shade) and bird activity (whether mobile / stationary) were consistently found to explain some of the variation in FID in this dataset. The relationships between the behavioural variables (plant species, bird location, bird exposure and bird activity) and air temperature were investigated and revealed a potential mechanism through which air temperature may also indirectly be affecting FID. The reduction in FID at high air temperatures, and thus the potentially increased risk of predation, may have negative consequences for these species in the Kalahari in light of rising air temperatures associated with climate change
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McGrath, Kate. "Long-term vegetation change in response to rest from grazing at Worcester Veld Reserve." Bachelor's thesis, University of Cape Town, 2002. http://hdl.handle.net/11427/25919.
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Hartley, Mary Luisa. "Breeding system and genetic variation in Tylosema esculentum." Thesis, University of Sussex, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.361301.
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Jouini, Meriem. "Evaluation environnementale des pratiques agricoles et des aménagements de conservation par ACV : cas du bassin versant de Merguellil de la Tunisie centrale." Thesis, Montpellier, SupAgro, 2019. http://www.theses.fr/2019NSAM0001.
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Dans les zones semi-arides, l'agriculture est basée sur des ressources "eau et sol" limitées et fragiles souvent surexploitées. Pour garantir la durabilité de la gestion des terres agricoles dans les territoires ruraux, l'évaluations environnementale doit être intégrée pour soutenir les décideurs et les acteurs locaux dans leur prise de décision. Grâce à son exhaustivité, l'analyse du cycle de vie (ACV) est l'un des outils les plus largement utilisés pour l'évaluation des impacts sur l'environnement. Elle présente des caractéristiques d’approche globale (tous les impacts environnementaux potentiels sont considérés) et de cycle de vie (« du berceau à la tombe »). Cependant, l’ACV est difficile à appliquer dans les zones rurales des pays en développement. Premièrement, l'ACV nécessite beaucoup de données difficiles à collecter en raison de la diversité des petits systèmes agricoles. Deuxièmement, les résultats de l'ACV sont difficiles à interpréter par les non-spécialistes en raison de la complexité de ses multiples indicateurs. Troisièmement, les processus pris en compte dans l’ACV ne correspondent souvent pas aux valeurs et aux intérêts des parties prenantes. Notre zone d'étude est située à l'amont du bassin versant de Merguellil, en Tunisie centrale, un pays méditerranéen, caractérisé par un climat semi-aride avec une forte variabilité des précipitations et elle est considérée comme une importante zone de recharge des aquifères. L'amont du Merguellil réunit des enjeux environnementaux majeurs tels que des ressources variables et limitées, la sur-exploitation des ressources en eau, le faible contrôle de l'accès à l'eau et une dégradation accélérée des sols. Ces problèmes sont également rencontrés dans tout le bassin méditerranéen. Le développement d’une agriculture irriguée de plus en plus intensive et l'expansion rapide des aménagements de conservation ont posé la question de leurs impacts environnementaux et particulièrement sur la ressource sol. Dans le cadre de la gestion des ressources communes "eau et sol" et de la prise en compte de la diversité des pratiques agricoles au sein d'un territoire agricole, il est important d'évaluer les impacts à l'échelle d'un territoire. Notre objectif principal est de fournir aux décideurs des connaissances sur les impacts environnementaux des aménagements de conservation des eaux et des sols (CES) et des systèmes agricoles les plus pertinents par ACV à l’échelle du territoire. Dans cette thèse, nous avons proposé une démarche participative progressive et itérative pour analyser le territoire par rapport à son historique, ses composantes (les territoires de vie), ses fonctions, ses productions agricoles et ses composantes sociales (les familles). Nous avons fourni des modèles conceptuels partagés par tous les acteurs et avons collecté et validé toutes les données nécessaires pour l’évaluation environnementale. Un cadre méthodologique innovant a été proposé pour coupler l’ACV à cette approche participative et a permis de réaliser l’analyse des impacts environnementaux de tous les systèmes de culture. Enfin, la prise en compte des impacts des ouvrages de conservation des eaux et des sols en ACV a fait l’objet d’un développement spécifique. Deux indicateurs ont été explorés à l’aide d’un modèle d’érosion distribué (LandSoil) : la résistance à l’érosion et la filtration mécanique. Ces développements fournissent toutes les méthodes et les données pour éclairer la décision dans le cadre d’une gestion participative du territoire, et en particulier pour définir une stratégie d’aménagement durable pour les ouvrages de conservation des eaux et des solsIn semi-arid areas, agriculture is based on limited and fragile "water and soil" resources that are often overexploited. To ensure the sustainability of agricultural land management in rural areas, environmental assessment must be integrated to support decision-makers and local stakeholders in their decision-making. Due to its comprehensiveness, life cycle assessment (LCA) is one of the most widely used tools for environmental impact assessment. It has global approach (all potential environmental impacts are considered) and life cycle thinking ("cradle to grave"). However, LCA is difficult to apply in rural areas of developing countries. First, LCA requires a lot of data that is difficult to collect because of the diversity of small farming systems. Second, the results of LCA are difficult for non-specialists to interpret because of the complexity of its multiple indicators. Third, the processes included in LCA often do not correspond to the values and interests of stakeholders. Our study area is located upstream of the Merguellil catchment in central Tunisia, a Mediterranean country, characterized by a semi-arid climate with high variability of precipitation and is considered an important recharge area for aquifers. The upstream Merguellil brings together major environmental challenges such as variable and limited resources, over-exploitation of water resources, poor control of access to groundwater and accelerated soil degradation. These problems are also encountered throughout the Mediterranean region. The rapid expansion of conservation measures and of intensive irrigated cropping systems have raised the question of their environmental impacts and particularly on the soil resource. In the context of managing common "water and soil" resources and taking into account the diversity of agricultural practices within a rural area, it is important to assess the impacts at the scale of a territory. Our main objective is to provide decision-makers with knowledge on the environmental impacts of water and soil conservation works (WSCW) and the most relevant cropping systems by LCA at the territory level. In this thesis, we proposed a progressive and iterative participatory approach to analyze the territory in relation to its history, its components (living territories), its functions, its agricultural productions systems and its social components (families). We provided conceptual models shared by all stakeholders, we also collected and validated all the data necessary for the environmental assessment. An innovative methodological framework was proposed to link LCA with this participatory approach and made it possible to analyse the environmental impacts of all cropping systems. Finally, the consideration of the impacts of water and soil conservation works in LCA has been the subject of a specific development. Two indicators were explored using a distributed erosion model (LandSoil): erosion resistance and mechanical filtration. These developments provide all the methods and data to inform decision-making in the context of participatory land management, and in particular to define a sustainable development strategy for water and soil conservation works
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Ffolliott, Peter F. "Arid Zone Forestry Program: State of Knowledge and Experience in North America." College of Agriculture, University of Arizona (Tucson, AZ), 1989. http://hdl.handle.net/10150/310780.
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Joshi, Bhaskar. "Estimation of diffuse vadose zone soil-water flux in a semi-arid region." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/nq23996.pdf.
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Ramadan, Mohamad Fahmy A. "Interactive urban form design of local climate scale in hot semi-arid zone." Thesis, University of Sheffield, 2011. http://etheses.whiterose.ac.uk/15120/.
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Jardine, Angela Beth. "Aqueous Phase Tracers of Chemical Weathering in a Semi-arid Mountain Critical Zone." Thesis, The University of Arizona, 2011. http://hdl.handle.net/10150/144594.
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Chemical weathering reactions are important for the physical, chemical, and biological development of the critical zone. We present findings from aqueous phase chemical analyses of surface and soil pore waters during a 15 month study in a small semi-arid mountain catchment of the Santa Catalina Mountain Critical Zone Observatory. Stream water geochemical solutes are sourced to two distinct locations - fractured bedrock baseflow stores and soil quickflow stores. Solid phase observations of albite, anorthite, and K-feldspar transformation to Ca-montmorillonite and kaolinite are supported by stream water saturation states calculated via a PHREEQC geochemical model. While differences in mineral assemblages, soil depths, and horizonation suggest greater weathering in schist versus granite lithologies and in hillslope divergent versus convergent zones, soil pore water solute ratio analysis does not readily distinguish these differences. However, preliminary investigation of aqueous rare earth elements suggests detectable lithologic and landscape positional differences warranting focus for future research efforts.
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Albaradeyia, Issa. "Modélisation de l'érosion en zone montagneuse semi-aride." Lille 1, 2007. https://pepite-depot.univ-lille.fr/LIBRE/Th_Num/2007/50376-2007-Albaradeyia.pdf.
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L'objectif du présent travail a été de déterminer les facteurs majeurs à l'origine de l'érosion des sols affectant la région des montagnes centrales située dans les territoires palestiniens. Ainsi, nous avons étudié l'effet de l'utilisation des différents terrains sur les propriétés du sol et choisi les meilleurs outils de modélisation pour prédire l'érosion des sols dans la région. L'analyse des paramètres pluviométriques a été effectuée ainsi que le calcul des paramètres pris en compte dans la modélisation de l'érosion des sols: érodibilité des sols et érosivité des précipitations. De même, l'analyse statistique a été réalisée pour vérifier l'effet des différents types d'utilisation de terrains sur les propriétés de sol, l'écoulement et l'érosion ainsi que pour définir la relation qui les relie. Deux logiciels "Hillslope" du projet de prévision d'érosion par l'eau (WEPP) et Réseau de Neurones Artificiels (RNA) ont été utilisés pour simuler l'écoulement et l'érosion des sols en s'appuyant sur divers scénarii. Concernant le RNA, une étude approfondie à base d'analyses de sensibilité utilisant la capacité de sensibilité d'analyse de RNA et d'analyse statistique, a été réalisée pour choisir les variables d'entrée les plus influentes. L'étude a montré que l'érosion dans le secteur d'étude dépend fortement de taux et de la durée des précipitations ainsi que son intensité comme souvent mentionnée dans la littérature. Les résultats obtenus par le modèle WEPP sont faibles en comparaison aux valeurs observées. Par contre, le modèle RNA donne des résultats très satisfaisants. Ainsi, le modèle global RNA, incluant l'ensemble des données issues des différents terrains utilisés, représente le meilIeur modèle en raison des résultats obtenus très proches de ceux mesurés. Le travail de thèse comporte cinq chapitres qui présentent successivement une synthèse bibliographique sur l'érosion des sols, la zone d'étude, une analyse des données de pluie, une analyse des mesures effectuées sur cinq parcelles et enfin la vérification de différents modèles sur les données collectées.
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Bourzat, Daniel. "Les petits ruminants dans les systèmes de production des zones aride et semi-aride de Somalie et du Burkina Faso." Paris 12, 1989. http://www.theses.fr/1989PA120032.
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Les enquetes, menees aupres de 361 exploitations de la somalie centrale et de 131 concessions du yatenga, ont permis d'etablir une typologie des unites de production agro-pastorales. Les performances des petits ruminants somaliens sont significativement liees aux conditions climatiques: l'age a la premiere parturition est superieur a deux ans; l'intervalle de mise-bas avoisine 14 mois; la fecondite est faible: 62% chez les ovins et 65% chez les caprins; la mortalite est elevee chez les jeunes animaux avant sevrage (13 a 51%). Les releves barymetriques et la description des robes (4653 animaux) ont permis la caracterisation des populations ovines et caprines. Chez les ovins et les caprins mossi et peul, les parametres zootechniques sont les suivants: l'age a la premiere parturition est de 15,0 mois chez les mossi, et de 13,9 et 14,7 mois chez les ovins et caprins peul; l'intervalle de mise-bas est de 9,4 et 9,5 mois chez les deux especes mossi et de 9,6 et 10,9 mois chez les brebis et chevres peul; le taux de reproduction annuel est de 1,36 et 1,51 chez les petits ruminants mossi et 1,33 et 1,7 chez les brebis et chevres peul; le taux de mortalite atteint 17,1% chez les agneaux et 20,6% chez les chevreaux. L'evolution des donnees ponderales et les effets des facteurs de variations sont analyses et discutes. Les resultats de la simulation demographique et economique confirment l'augmentation sensible de revenu net par reproductrice grace a la mise en uvre des techniques suivantes: plan de prophylaxie, enrichissement des sous-produits de recoltes a l'uree, supplementation minerale, embouche intensive des jeunes ovins males, choix des reproducteurs, controle de l'abreuvement. Les structures de developpement, capables de gerer ces techniques nouvelles, pourraient etre des associations de paysans ou d'eleveurs
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McClurg, Lorne W. H. "Validation of a methodology for observing biomass dynamics in photographs of arid zone vegetation /." Title page, contents and abstract only, 1993. http://web4.library.adelaide.edu.au/theses/09AR/09arm1264.pdf.
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El-Hames, A. S. "A physically-based model for the prediction of flood hydrographs in arid zone catchments." Thesis, University of Cambridge, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.306990.
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Lloyd, Penn. "A study of the ecology of the Namaqua Sandgrouse and other arid-zone birds." Doctoral thesis, University of Cape Town, 1998. http://hdl.handle.net/11427/9680.
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Bibliography: leaves [148]-164.This field study set out to identify the key ecological factors influencing the population dynamics of the Namaqua Sandgrouse Pterocles namaqua, through an investigation of diet and the nutritional demands during different stages of the annual cycle, the timing of breeding seasons and movements in relation to patterns of rainfall-dependent food availability, breeding success and the factors limiting productivity. In addition, the nesting habits and success of 11 coexisting arid-zone bird species were examined to test a variety of hypotheses regarding the relationship between nest-predation rate and nest site, nest density, predator-avoidance behaviour, stage of the nesting cycle and season, and degree of residency. Furthermore, the importance of rainfall as a breeding stimulus and its effects on clutch size were investigated for several species. The Namaqua Sandgrouse is an obligate granivore at all times, feeding on the seeds of annual plants, primarily of the family Fabaceae. Even while breeding, energy is the first-limiting nutrient in the foods of adults. Growing chicks have a proportionally greater protein demand, and are more dependent than adults on protein-rich legume seeds to satisfy first-limiting amino acid requirements. The chick growth phase was identified as the most nutritionally demanding stage in the annual cycle. The breeding season was found to be unexpectedly variable, and not consistently correlated with periods of peak food availability.
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Sun, Bo. "Spatio-temporal modelling of landuse and land cover change in arid zone, northwest China." HKBU Institutional Repository, 2010. https://repository.hkbu.edu.hk/etd_ra/1163.
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Qian, Jing. "Analyzing and modelling the spatio-temporal pattern of urban expansion in China's arid zone." HKBU Institutional Repository, 2012. https://repository.hkbu.edu.hk/etd_ra/1396.
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Piers, Laetitia. "Implications of potential biome boundary shifts for small mammal assemblages in the arid zone." University of the Western Cape, 2019. http://hdl.handle.net/11394/7051.
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Magister Scientiae (Biodiversity and Conservation Biology)Desertification deteriorates the landscape functionality of rangelands, affecting the resilience of biome boundaries which have a cascade effect not only in vegetation composition and characteristics but also in animal communities. The balance between plants and small mammals are essential in maintaining the functionality (i.e. nutrient cycling, soil stability, and water infiltration) of rangeland which includes the arid Steinkopf communal rangeland. However, the landscape functionality of rangelands has not been extensively studied, especially in communal areas where desertification is a serious concern since many people farm with livestock to survive. The aim of this study was to assess landscape functionality along an arid biome boundary and its relationship to small mammal assemblages. This study further aimed to provide a local landscape perspective of the current desertification process and projected expansion of the Desert Biome into more mesic biomes in South Africa. Three replicates for three Desert Biome, ecotone and Succulent Karoo Biome sites (27 sites in total) were selected to assess landscape functionality and survey small mammal assemblages over a one-year period. The change in landscape functionality between the three areas was assessed to determine the resilience of the biome boundary to desertification. For each small mammal survey, 216 live Sherman traps were set up during the summer and winter seasons to account for breeding, mortality, and possible migration. With the data, the body condition index, population density, and diversity were quantified.
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Harrington, Rhidian. "The effects of artificial watering points on the distribution and abundance of avifauna in an arid and semi-arid mallee environment." Connect to this title online, 2002. http://repository.unimelb.edu.au/10187/2874.
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The role of artificial watering points in the avifaunal dynamics of the semi-arid mallee woodlands of southeast Australia was examined. Species richness and abundance were monitored throughout the year at different distances from water to determine how birds were distributed around water points and how this changed in relation to environmental factors such as climate. Vegetation attributes were also measured to determine which factors explained patterns in the avifauna with distance from water, and also to allow a description of the vegetation in relation to the water points. Water points were monitored throughout the year to determine which species were utilising them, under which environmental circumstances and for what purposes. Knowledge of the water utilisation behaviour of individual bird species allowed some explanation of their distribution patterns, as well as an ability to predict the likely effects of water point closure on those bird species. The closure of two water points during the study allowed an assessment of the immediate effects of water point closure on avifauna (For complete abstract open document)
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Chebbi, Wafa. "Caractérisation des échanges d'eau et d'énergie dans une oliveraie pluviale en zone aride : modélisation et intégration des données de télédétection." Thesis, Toulouse 3, 2019. http://www.theses.fr/2019TOU30111.
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L'olivier est un agrosystème pérenne clé pour l'économie du pourtour méditerranéen avec des pratiques culturales contrastées (sec épars/irrigué intensive, co-planté...). Connu pour ses mécanismes d'adaptations au stress hydrique et sa capacité de survivre durant de longues périodes à conditions limitantes en eau de sol, l'oléiculture pluviale est dominante dans cette zone, notamment en Tunisie et l'écartement entre les arbres est une fonction de la distribution de la pluviométrie (un nombre important de pieds à l'hectare au Nord (6 m) et des oliveraies très éparses au Sud (25 m)) assurant un volume de sol exploré par les racines supposé être suffisant pour satisfaire les besoins en eau des oliviers. Il est cependant soumis à une forte pression climatique du fait des sécheresses récurrentes dont la fréquence et l'intensité risquent de s'accentuer dans les décennies qui viennent. La réponse de ces couverts épars, où l'eau est un facteur limitant, à ces changements climatiques est méconnue. Dans ce contexte, ce travail vise à améliorer notre connaissance des processus physiques régissant le cycle hydrologique et le développement de la végétation dans une oliveraie pluviale au centre de la Tunisie. L'objectif de cette thèse est double : i/tester la vulnérabilité de ces oliveraies éparses face aux conditions extrêmes futures et ii/proposer des solutions aux agriculteurs à court (par exemple l'irrigation localisée de complément) et à long termes (notamment la diminution des écartements entre les arbres ou l'extension des périmètres irrigués). Pour répondre à ces objectifs, nous avons besoin de bien caractériser le fonctionnement thermo-hydrique des oliviers, d'identifier la possibilité de suivre leur état hydrique actuel et de prédire leurs réponses à des conditions hydriques futures plus sévères. Dans un premier temps, un protocole expérimental dédié qui comprend des mesures par la méthode de fluctuations turbulentes et la méthode de flux de sève a été mis en place. Les données collectées qui renseignent sur les échanges d'énergie et de matière au sein du continuum sol-plante-atmosphère, ont été analysées et leur cohérence a été vérifiée à travers une étude des différentes composantes des bilans hydrique et énergétique à différentes échelles spatiales et temporelles. En plus de mesures directes, des mesures de proxidétection ont été sélectionnées afin d'analyser l'apport de cet outil puissant. Des relations entre les indices de stress hydrique estimés (par exemple l'écart entre la transpiration réelle et potentielle) et les indicateurs de proxidétection (la température de surface et le photochemical reflectance index) ont été donc établies pour détecter les seuils critiques au-delà des quels un apport en eau devient indispensable pour la survie de la plante. Dans un second temps, un modèle d'échanges sol-plante-atmosphère ISBA a été calé et validé en s'appuyant sur l'important jeu de données observé pour reproduire le fonctionnement des oliviers. Cette étude souligne que le caractère épars des oliviers est néanmoins un défi pour l'application de ces outils car la fraction de couverture de végétation (moins de 7 % pour notre site de Nasrallah) est telle que la surface est dominée par le fonctionnement du sol nu. Des ajustements ont été donc proposés voire apportés aux méthodes utilisées pour les adapter à ce faible taux de couvert végétal. La base de données utilisée pour cette étude est publiée sous le DOI : 10.6096/MISTRALS-SICMED.1479The olive tree is a key perennial agrosystem for the economy of the Mediterranean basin with contrasting farming practices (rainfed sparse/intensive irrigated, co-planted ...). Known for its mechanisms of adaptation to water stress and its ability to survive for long periods under soil water limiting conditions, rainfed olive cultivation is dominant in this area, especially in Tunisia and the spacing between trees is a function of the distribution of the precipitation (from high density of plantation in the North (6 m) to very sparse in the South (25 m)) ensuring a volume of soil explored by the roots that is assumed to be enough to satisfy the water needs of the olive trees. However, it is subject to severe climatic pressure due to widespread dry spells, for which the frequency and intensity is likely to increase in the coming decades. The response of these sparse covers, where water is a limiting factor, to these climatic changes is unrecognized. In this context, this work aims to improve the current understanding of the physical processes governing the hydrological cycle and the development of vegetation in rainfed groves in central Tunisia. There is a twofold purpose: I / to test the vulnerability of these sparse olive groves to future conditions and ii / to make a decision support to farmers for the short (i.e., localized supplementary irrigation) and in the long term (in particular a decrease of the spacing between trees or the extension of irrigated area). To meet these goals, it is necessary to characterize the thermo-hydric functioning of olive trees, to identify the possibility of monitoring their current water status and to predict their responses to more severe future water conditions. As a first step, a dedicated experimental set up that includes eddy covariance and sap flow measurements has been installed. The collected data, which provide information on the exchange of energy and matter within the soil-plant-atmosphere continuum, were analyzed and their consistency was verified through a study of the different components of the water and energy balances at different spatial and time scales. In addition to direct measurements, proxidetection measurements are available and allow investigating the benefit of this powerful tool. Relationships between the estimated water stress indices (e.g., the difference between actual and potential transpiration) and the proxidetection indicators (surface temperature and photochemical reflectance index) were therefore established to detect critical thresholds beyond which a water supply becomes essential for the survival of the plant. In a second step, a soil-plant-atmosphere ISBA exchange model was calibrated and validated based on the large data set observed to reproduce the functioning of olive trees. This study emphasizes that the sparse nature of olive trees is nevertheless a challenge for the application of these tools because the fraction of vegetation cover (less than 7% for our Nasrallah site) is such that the surface is dominated by the bare soil functioning. Adjustments have therefore been proposed or even applied to these methods to adapt them to this low fraction vegetation cover. The database used in this study is published under the DOI: 10.6096/MISTRALS-SICMED.1479
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Bouragba, Latifa. "Etude de la recharge artificielle des nappes en zone semi-aride : application au bassin du Souss-Maroc." Thesis, Besançon, 2011. http://www.theses.fr/2011BESA2046.
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La plaine du Souss est délimitée au nord par le Haut-Atlas, au sud par l’Anti-Atlas et à l’estpar le massif cristallin de Siroua. Les principales formations géologiques sont des marnocalcaireset conglomérats assez perméables, les calcaires du Turonien qui leur sont sousjacentset le lit fossile de l’oued Souss composé d’alluvions sablo-graveleuses trèsperméables.La nappe du Souss est la plus importante du sud du Maroc, elle est très exploitée par unsecteur agricole exportateur, la surexploitation de la nappe s’est traduite par une baissecontinue des niveaux. Depuis 1970, les prélèvements dépassent de loin les ressourcesrenouvelables de la nappe (déficit : 185 Mm3 en 1976, 358 Mm3 en 1998, 228 Mm3 en 2003).Le barrage d’Aoulouz est principalement destiné à la recharge artificielle de la nappe par deslâchers d’eaux stockées pendant les périodes pluvieuses. En zone semi-aride, une estimationprécise de la recharge est souvent délicate, la variabilité spatio-temporelle de la recharge étantgénéralement forte et les processus variés.Ce travail a permis de mieux caractériser l’impact de la recharge sur la nappe et d’évaluer letemps de séjour et le renouvellement des eaux souterraines.L’évolution de la piézométrie à la suite des lâchers d’eau à partir du barrage Aoulouz montredes remontées locales du niveau piézométrique sur la haute plaine, environ 85% des eauxlâchées à partir du barrage d’Aoulouz s’infiltrent 80 km entre Aoulouz et Taroudant.Toutefois, le niveau général de la nappe continue de baisser.Le faciès géochimique est principalement bicarbonaté calcique (dissolution des carbonates), etpar endroits sulfaté calcique (évaporites au pied du Haut-Atlas). Les eaux de surface ont unfaciès bicarbonaté calcique et magnésien acquis lors de leur circulation sur des calcaires et desdolomies.[...]The Souss valley is bounded to the North by the High Atlas, to the South by the Anti-Atlasand to the East by the Siroua crystalline massif. The main geological formations arecalcareous marls of the Plio-Quaternary, the Turonian limestones that underlie them, and thefossil bed of River Souss formed by sands, sandstones and gravels from high permeabilityalluvium.The Souss aquifer is the most significant aquifer in southern Morocco, highly exploited by anagricultural exporting activity. Groundwater overexploitation induced a decreases ofpiezometric heads. Since 1970, water demand far exceeds renewable groundwater resources(balance defecit: 185 Mm3 in 1976, 358 Mm3 in 1998, and 228 Mm3 in 2003).The mean role of the Aoulouz dam is the artificial recharge of the Souss plain by release ofwater stored during rainy periods in the plain.In semi-arid areas, estimating recharge is often difficult, the spatial and temporal variabilitiesof recharge are generally high, and processes are varied.This work has enabled to characterize the impact of artificial recharge and to estimate therenewal of water in the aquifer.Water releases from Aoulouz dam has permitted an increase of the piezometric level on thehigh plain, about 85% of the water released are unfiltered in the first 80 Km between Aoulouzand Taroudant cities. However, the general water level decline goes on.The geochemical facies is mainly calcium bicarbonate type (dissolution of limestone), andlocally calcium sulphate type (evaporites of the High Atlas). Surface waters are a calcium andmagnesium bicarbonate types, acquired during their flow through limestones and dolomitesoutcrops.[...]
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Al-Hasem, Ahmed M. "Coastal morphodynamics of an open-ended tidal channel in an arid and mesotidal environment : Al-Subiya Tidal Channel, Kuwait /." St. Lucia, Qld, 2001. http://www.library.uq.edu.au/pdfserve.php?image=thesisabs/absthe16464.pdf.
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Easton, Lyndlee Carol, and lyndlee easton@flinders edu au. "LIFE HISTORY STRATEGIES OF AUSTRALIAN SPECIES OF THE HALOPHYTE AND ARID ZONE GENUS FRANKENIA L. (FRANKENIACEAE)." Flinders University. Biological Sciences, 2008. http://catalogue.flinders.edu.au./local/adt/public/adt-SFU20081124.105244.
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This thesis is a comparative study of the life history strategies, and in particular seed germination requirements, in Australian species of the halophyte plant genus Frankenia L. (Frankeniaceae). Frankenia is a cosmopolitan genus that occurs in Mediterranean, semi-arid, and arid regions on distinctive soil types commonly on saline, sodic or gypseous soils in habitats such as coastal cliffs, and on the margins of salt lakes, salt-pans and saltmarshes (Summerhayes 1930; Barnsley 1982). The plants are small shrubs or cushion-bushes with pink, white or pale purple flowers, and salt-encrusted recurved leaves.
This project investigates germination requirements for Frankenia in relation to seed age, light requirements, temperature preferences, salinity tolerance, and soil characteristics. It also explores two divergent reproductive strategies notably seed packaging strategies in relation to environmental variables. Within the 46 currently recognized endemic Australia species, some species have a few ovules per flower and produce only a few larger seeds per fruit, while other species have many ovules per flower and produce many small seeds per fruit. Large-seededness is thought to increase the probability of successful seedling establishment in drought and salt-stressed environments. As both larger- and smaller-seeded species of Frankenia co-occur in close geographical proximity, hypotheses regarding the advantages of large-seededness in stress environments can be tested. By restricting the analysis of seed mass variation to similar habitats and within a single plant genus, it is possible to test ecological correlates that would otherwise be masked by the strong effects of habitat differences and phylogenetic constraints.
Overall, larger-seeded Frankenia species were demonstrated to be advantageous for rapid germination after transitory water availability, and for providing resources to seedlings if resources became limiting before their successful establishment. Smaller-seeded species delayed germination until both soil-water availability and cooler temperatures persisted over a longer time period, improving chances of successful establishment for the more slowly growing seedlings that are more reliant on their surroundings for resources.
This study produces information on the seed and seedling biology of many Australian species of Frankenia including several that are of conservation significance, e.g. F. crispa with its isolated populations, and the rare and endangered F. plicata. This information is important for the development of conservation management plans for these and other arid zone, halophyte species. In addition, the results of this study are of practical significance in determining the suitability of Frankenia for inclusion in salinity remediation and mine-site rehabilitation projects, and for promoting Frankenia as a drought and salt tolerant garden plant.
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Pert, Petina Lesley, and petina pert@bigpond com. "Biodiversity Conservation at the Bioregional Level: a case study from the Burt Plain Bioregion of Central Australia." RMIT University. Mathematical and Geospatial Sciences, 2006. http://adt.lib.rmit.edu.au/adt/public/adt-VIT20070209.120654.
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This thesis considers ways to improve biodiversity conservation at the bioregional level in Australia through the use of geospatial science technologies and biological modelling techniques. Following a review of approaches to biodiversity conservation at the bioregional level, including the roles and potential of geospatial science technologies in this regard, I consider biodiversity modelling using a case study of the Burt Plain bioregion in central Australia that focuses on selected taxa, ecosystems and landscapes. The Burt Plain bioregion was chosen since it is one of 19 bioregions nationally that has been given a 'very high' priority status for biological survey, assessment and potential reservation of land for conservation purposes. The specific research objectives for the Burt Plain bioregion study were to: · describe the species composition, distribution and nature of the dominant vegetation communities within the bioregion; · characterise environmental niche of communities with respect to selected environmental and management variables - latitude, longitude, climate, land systems and land units, geology, hydrography, topography, and tenure; · analyse how well or otherwise taxa have been sampled (during previous ground surveys) with respect to geographical and environmental variables; Biodiversity conservation at the bioregional level · develop and compare quantitative habitat models of the potential distribution of selected species based on presence-only distributional data; and · examine the significance of radiometric data as a potential correlate and predictor of the distribution of those selected species. National conservation initiatives such as the bioregional approach and international initiatives such as the biosphere reserves program to support the planning and management of biodiversity conservation are discussed in chapter two. The scientific and related processes underpinning the development of bioregions and strategies across the Australian states and territories are then considered. An important finding arising from this review is the need to improve biological information, especially through systematic surveys and on-going monitoring of ecosystems and populations of species, at the bioregional level to inform land use allocation and management. This finding is consistent with one of the general aims of the thesis to improve the spatial modelling techniques available for bioregional assessment and biodiversity conservation. In chapter three I review the role and limitations of geospatial technologies currently employed for biodiversity conservation management. Current developments and applications of GIS and remote sensing to wildlife research, conservation gap analysis and conservation reserve design are considered. Geographic information systems (GIS) are now routinely used by ecologists to Biodiversity conservation at the bioregional level analyse spatial data. Although various forms of GIS have been available for 15 to 25 years, the biological applications of GIS have figured most prominently in the ecological literature only in the past 15 years. The use of computer-generated models to simulate environmental events can provide a greater understanding of ecosystems, and offers improved predictive powers to conservation and land managers. The decision support offered by computer-based modelling techniques appears likely to underpin conservation and management decisions much more into the future providing that adequate biological and other datasets are available for this purpose. Dominant vegetation communities and various environmental gradients were analysed to characterise environmental niches at the bioregional scale for the Burt Plain bioregion (Chapter 4) and more locally at the catchment scale for the Upper Todd River Catchment (Chapter 5). In Chapters four and five I describe in detail the land tenure and use, land systems, climate soil, geology, topography, hydrology, vegetation and biodiversity of the Burt Plain bioregion and Upper Todd River Catchment. The bioregion contains some ephemeral watercourses, which are generally in fair to good condition, but are afforded little protection from a range of threatening processes, including grazing and trampling by feral animals and livestock and weed infestation. The major river systems occurring in the bioregion include parts of the Plenty, Hanson, Sandover and Lander Rivers. In the Upper Todd River Catchment the major watercourses Biodiversity conservation at the bioregional level are the Todd River and Station Creek, which exit the area via two narrow gaps in the low rocky hills on the southern boundary of the bioregion. The dominant geology can be summarised as plains and low rocky ranges of Pre-Cambrian granites on red earths. The bioregion has approximately 200 - 250 mm of summer rainfall, with rainfall occurring on 20 - 30 days per year. There is a high variability and range of temperatures, with an annual mean temperature of approximately 22-23°C. In Chapter six I consider a range of species found within the Burt Plain bioregion using existing survey data and techniques that enables the prediction of the spatial distribution of taxa. Using GLM and GAM models, Black-footed Rock- Wallaby (Petrogale lateralis), Spinifex Hopping Mouse (Notomys alexis) and Spencers Frog (Limnodynastes spenceri) were chosen for a more in-depth analysis. Environmental variables correlated with the presence of each species are then described and prediction maps showing the probability or likelihood of the presence of the species within the bioregion developed. In Chapter seven I examine the utility of radiometric data for wildlife habitat modelling. Statistical relationships are tested between the concentrations of the elements uranium, thorium and potassium and terrain characteristics such as position in the landscape, slope and aspect as well as other climatic variables. Radiometric data were found to be useful for developing statistical predictive Biodiversity conservation at the bioregional level models of six species: Red Kangaroo (Macropus rufus), Desert Dunnart (Sminthopsis youngsoni), Rabbit (Orcytolagus cuniculus), Brown Honeyeater (Lichmera indistincta), Little Spotted Snake (Suda punctata) and Southern Boobook (Ninox novaeseelandiae). I suggest that the utility of radiometric data for wildlife habitat modelling would appear significant and should be explored further using alternative quantitative modelling techniques and presence/ absence records for target faunal species. Predictions of species distributions may be useful for prioritising land acquisitions for reservation as well as in the future design of biological surveys. The thesis concludes with a synthesis of the major research findings, discussion of the limitations of the datasets available for the study, perspectives on management issues in the Burt Plain bioregion, and possible future research directions. It is important that purposefully-designed biological survey research be undertaken across the bioregions of the arid zone of Australia to enhance basic understanding of biodiversity patterns and their relationships to environmental heterogeneity and site-landscape level processes. Geospatial modelling techniques can assist such biodiversity survey and evaluation and make their conduct more cost-efficient and the inferences drawn from subsequent data analyses more powerful. This knowledge is required to contribute to the emergent concepts and theory of ecosystem dynamics and associated biodiversity patterns in arid Australia and, most significantly, to enhance the conservation and management of the unique biological complement and systems found in this region.
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Pierre, Caroline. "Variabilité interannuelle des émissions d'aérosols minéraux en zone semi-aride sahélienne." Phd thesis, Université Pierre et Marie Curie - Paris VI, 2010. http://tel.archives-ouvertes.fr/tel-00921688.
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Les aérosols minéraux constituent une des plus importantes sources en masse des aérosols atmosphériques. Ces particules ont différents impacts sur l'environnement : elles exercent un forçage radiatif, et peuvent intervenir dans la chimie hétérogène atmosphérique, ainsi que dans la dynamique des nuages. Elles jouent aussi un rôle dans la redistribution de matière à l'échelle globale, notamment par leur dépôt loin des zones sources. L'estimation des quantités d'aérosols minéraux présents dans l'atmosphère, et donc de leurs flux d'émission, qui se font sous l'action du vent en zones arides et semi-arides, demeure l'objet de fortes incertitudes. Si les émissions de particules minérales en zones arides sont relativement bien contraintes à l'heure actuelle, les processus d'érosion éolienne en zones semi-arides sont plus complexes, en raison notamment de la dynamique des états de surface. L'objectif de cette étude est de quantifier les émissions d'aérosols minéraux par érosion éolienne en zone semi-aride sahélienne, et plus précisément d'estimer l'impact de la végétation saisonnière sur ces émissions, sans prendre en compte à ce stade les perturbations induites par l'action de l'homme. Nous avons mis en œuvre des outils de modélisation pour simuler le couvert végétal saisonnier et l'émission d'aérosols par érosion éolienne. La zone d'étude est la ceinture sahélienne, de 10°N à 20°N et de 20°W à 35°E. Les résolutions spatiales retenues sont de 0.10° à 0.25° et 0.5°, et la résolution temporelle de 1 à 10 jours. Afin de pouvoir tenir compte de la variabilité interannuelle des phénomènes observés, la couverture temporelle de l'étude est de 4 ans, sur la période 2004-2007. En régions semi-arides, la disponibilité en eau est le principal facteur limitant le développement de la végétation. Trois produits d'estimation des précipitations issus d'observations satellitaires (CMORPH, RFE2.0 et TRMM3B42) ont donc été comparés entre eux et comparés à des mesures de pluviomètres spatialement interpolées (AGHRYMET), au cours de la saison des pluies au Sahel. Trois critères de comparaisons ont été définis pour qualifier leur pertinence en termes de dynamique de la végétation (distribution spatiale, fréquence journalière et quantités des précipitations). Les trois produits sélectionnés montrent un bon accord sur la ceinture sahélienne, et ce pour les trois critères. De plus, le niveau d'accord est stable au cours du temps, de l'échelle intrasaisonnière à l'échelle interannuelle. La végétation est simulée avec le modèle STEP, conçu spécifiquement pour reproduire la dynamique de la végétation sahélienne. Les simulations sont réalisées en utilisant en entrée les trois champs de pluie issus de l'étape précédente. Les résultats sont comparés à des observations régionales issues de mesures satellitaires (LAI MODIS). Les critères de comparaisons sont déterminés pour leur pertinence en termes de caractérisation de l'état de la surface (limite nord, dates de démarrage et de maximum, et valeurs du maximum de végétation). Ces comparaisons montrent la capacité du modèle utilisé à reproduire la dynamique régionale annuelle. Les différentes phases du cycle végétatif sont bien restituées, avec toutefois des réserves sur le démarrage précis de la pousse. Les émissions d'aérosols désertiques sont simulées en utilisant le modèle DPM, qui repose sur la description explicite des processus physiques mis en jeu. Les caractéristiques des états de surface en l'absence de végétation (rugosité, types de sol) sont décrites en se basant sur des produits de surface satellitaires et de données issus de d'analyses géomorphologiques. En période végétative, les caractéristiques du couvert végétal simulé (hauteur, taux de couverture) sont converties en termes de rugosité dynamique de la surface. L'effet de l'humidité gravimétrique de la couche superficielle du sol est également pris en compte. L'impact de ces différents facteurs est alors illustré, notamment les différences dues à la présence du couvert végétal, en termes d'émissions d'aérosols minéraux, dans une zone définie comme la " frange émissive saisonnièrement végétalisée ", et dont l'étendue varie selon l'année et le produit de pluie utilisé en forçage. Pour la période 2004 à 2007, la strate herbacée saisonnière présente ainsi une capacité d'inhibition des émissions de l'ordre de 8 à 28% en masse du flux total annuel de cette frange, qui lui peut varier de 1 à 30 Mt environ.
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Khoshbinroudi, Farangis. "La ville traditionnelle iranienne : conception compacte et bioclimatique en zone aride." Thesis, Université Paris-Saclay (ComUE), 2019. http://www.theses.fr/2019SACLD005.
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Une grande part de la consommation énergétique des bâtiments en Iran provient du pétrole, du gaz et de l'électricité, alors même que les ressources en énergies fossiles s'épuisent dans le pays. De plus, la consommation énergétique moyenne y est plus importante que dans d'autres pays, y compris des pays qui disposent de ressources importantes en énergies fossiles, tandis que les subventions accordées par le gouvernement Iranien renforce encore cette tendance en rendant bon marché sur le marché intérieur les prix du pétrole et du gaz. Bâtiments et maisons représentent une part moyenne importante de l'énergie totale consommée dans le pays, à hauteur de 42%, et les énergies renouvelables ne sont utilisées que de façon marginale. En contraste, les villes Iraniennes avaient, depuis des milliers d'années, su s'appuyer sur des techniques de construction, d'architecture et d'urbanisme leur permettant de revendiquer un profil de faible consommation énergétique, instaurant ainsi un équilibre durable avec leur environnement. Cette recherche s'attache à comprendre les principes et les techniques utilisés dans la conception de l'architecture urbaine traditionnelle de la ville de Yazd, située dans le centre de l'Iran, afin de fournir des éléments précis d'optimisation énergétique des espaces urbains. Cette recherche s'avère fondamentale en termes d'orientation, avec l'objectif d'atteindre des résultats applicables dans le contexte contemporain en utilisant une méthode exploratoire. Le recueil des données nécessaires à cet exercice a été réalisée en deux temps. Dans un premier temps, par une méthode documentaire s'appuyant sur des textes historiques, sur des écrits d'historiens reconnus comme autoritaires, et sur l'étude de plans et de cartes détaillants le développement urbain. Dans un second temps, par une investigation conduite directement sur le terrain ainsi que par des rencontres avec des professionnels et des universitaires. S'appuyant sur l'ensemble des données recueillies, l'analyse de la situation actuelle dans la zone étudiée a été réalisée en utilisant la méthode de description qualitative. Finalement, tenant compte du système centralisé de gestion urbaine en Iran, nous avons proposé de mettre à disposition le fruit de notre étude auprès des entités administratives compétentesMost of the energy consumption of buildings in Iran comes from oil, gas and electricity sources, while fossil fuel resources are running out in Iran. In addition to that, the country's average energy consumption is higher than other countries and even some oil-rich countries, while government subsidies and cheap oil and gas resources has exacerbated this critical situation. Buildings and houses with an average consumption share of 42.41 percent has a high share of energy consumption of the country and renewable energies are used only marginally. In contrast to this situation, Iranian cities, for thousands of years, have had a low consumption pattern of energy with the use of architectural and urban construction techniques and have come to a permanent and sustainable coexistence with their surroundings. This research seeks to understand the principles and techniques of constructing the traditional urban architecture of Yazd in the centre of Iran to provide in-depth insights toward energy optimization in urban areas. Moreover, the global methods of sustainable urban development are studied and compared to extract a set of guidelines for improving urban conditions in the traditional areas of Yazd. This research is fundamental in terms of orientation, and the purpose is exploration and being applicable. The compilation of the required data is done in two ways firstly) documentary method with the use of historical texts, authoritative writings of historians, and review of urban development plans such as comprehensive and detailed plans, and secondly field observations and meetings with practitioners and faculties have been conducted. Based on the gathered information, analysis of the current situation in the studied area has been carried out using qualitative descriptive method. Finally, with the consideration to the centralized urban management system of Iran, we proposed a method for transferring these results to the administrative sectors?
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Abdillahi, Boeuh Ahmed. "La gestion durable de l'eau en zone aride : le cas de la ville de Djibouti." Thesis, Bordeaux, 2016. http://www.theses.fr/2016BORD0104.
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La question de l’accès à l’eau potable se pose avec acuité pour les pays de la régionsubsaharienne où un individu sur trois n’a pas accès à une source d’eau améliorée.L’objectif de cette thèse vise à définir les conditions d’une gestion durable de l'eau pourla ville de Djibouti. Dans ce contexte, la question de l'approvisionnement en eau estenvisagée dans une perspective patrimoniale afin de tenir compte des particularités dela ressource en zone aride et des usages spécifiques qui lui sont associés dans unenvironnement marqué par la pauvreté. Un apport majeur de la thèse réside d'une partdans l’analyse du contenu d’une politique durable de l'eau à Djibouti en présenced’inadéquation entre l’offre et la demande de l’eau et, d'autre part, des implications decette politique en termes de tarification de la ressource selon les usages mais aussi enterme de répartition plus équitable de l'eau au sein de la population. La première partiede la thèse s’intéresse à l’étude de la disponibilité de cette ressource rare à travers sonmode de gestion ainsi qu’à sa mesure à l’aide d’indicateurs. Elle propose également uncadre d’analyse de la ressource en resituant les principaux concepts utiles à ladéfinition d’une gestion durable de l’eau. La seconde partie met l’accent sur l’analysedes déterminants de la demande en eau et des choix en matière d’approvisionnementpour Djibouti-ville. Pour ce faire, elle s’appuie sur une étude économétrique réalisée àpartir d’enquêtes auprès d’un échantillon de 400 ménages. L’estimation d’un modèleprobit multivarié permet de considérer que le choix d’être raccordé à un branchement àdomicile dépend des caractéristiques socio-économiques du ménage. Cette thèseapporte des résultats originaux sur l’accès à l’eau des ménages et montre en particulierle rôle joué par des facteurs tels que le revenu, la taille de la famille ou le niveaud’éducation du chef de famille dans les choix opérés par les ménagesThe issue of access to drinking water is one which is of paramount importance for thecountries of the sub-Saharan region where one individual out of three does not haveaccess to a water source. The aim of this thesis is to determine the conditions ofsustainable water management for the city of Djibouti. In this context, the issue ofwater supply is considered from an asset perspective in order to take into considerationthe peculiarities of this resource in a dry zone and its uses in particular in anenvironment marked by poverty. The main contribution of this thesis lies not only inthe analysis of the content of a sustainable water policy in Djibouti at a time when isthere is discrepancy between supply and demand, but also with an examination of theimplications of such a policy in terms of the pricing of this resource based on both itslevel of use and on a more even distribution within the population. The first part of thisthesis deals with an analysis of the access to this scarce resource according to how it ismanaged and measured with the help of indicators. A framework is then developedwith the help of some main concepts that are useful for defining a sustainablemanagement of water. The second part emphasizes the study of the determinants ofdemands in water and the choices in terms of the supply for Djibouti-city by using aneconometric study based on investigations into a sample of 400 households. Theassessment of multivariate probit model allows taking into account the connection of ahousehold to the service depends on its socio-economic markers. This thesis generatenew findings about household access to water supply and highlights the extent towhich such factor as income, the household size or the level of education of the head ofthe family influence the choices made by the household
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Rasheeduddin, Mohammed. "A groundwater resources development study of a regional arid zone multi-aquifer system : Eastern Province, Saudi Arabia." Thesis, University of Birmingham, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.272620.
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Pirie, Anne. "Chipped stone variability and approaches to cultural classification in the Epipalaeolithic of the south Levantine arid zone." Thesis, Durham University, 2001. http://etheses.dur.ac.uk/3777/.
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This thesis examines how our picture of the Epipalaeolithic of the southern Levant has been structured, what its evidential base is and how it has gained authority. Hitherto, research has focused on describing variability in microliths, the type-fossil of the period, in terms of archaeological cultures using typology. Narrative analysis was used in the first part of this thesis to explore the work of three main researchers in the field. This has shown that narrative strategies are indeed employed in archaeological texts to describe lithic and other data creating a picture of the period that relies substantially on ideas 'imported' from modern attitudes to the region and the relations of people within it. The techniques of narrative are used to pull together the disparate and conflicting data we work with into a unity of significance, embodying authority and plausibility. In the second part of the thesis, a study of 12 chipped stone assemblages from the Negev and southern Jordan was undertaken. Attribute analysis was used to explore variability within and between sites. This has revealed a complex and cross-cutting pattern of personal or local decisions taken within a context of wider norms, which has created very specific tool forms at individual sites. A picture of context dependent variability was discovered that has not been reflected in the traditional typological methods. This offers new ways of seeing the relationships between social organisations and material culture.
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Bourzat, Daniel. "Les Petits ruminants dans les systèmes de production des zônes aride et semi-aride de Somalie et du Burkina Faso." Grenoble 2 : ANRT, 1988. http://catalogue.bnf.fr/ark:/12148/cb376122191.
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Greenville, Aaron C. "The role of ecological interactions: how intrinsic and extrinsic factors shape the spatio-temporal dynamics of populations." Thesis, The University of Sydney, 2015. http://hdl.handle.net/2123/13561.
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How individuals respond to environmental demands and pressures from conspecifics and from other species determines whether they will survive and reproduce, and hence whether their populations will persist. However, not all environments are benign or predictable, and not all populations of the same species respond to environmental pressures in the same way. The overall objective of this thesis was to incorporate both biotic and abiotic interactions into one conceptual framework to better understand and predict how species’ populations change across space and time. To help progress this objective, I built a trophic interaction model to capture the complexity of biotic and abiotic interactions in a model arid system, using long-term (over 20 years) ecological data on small vertebrates, climate and vegetation replicated across a large spatial area (8000 km2). The model was built upon smaller components that investigated the spatial and temporal dynamics of species’ populations and their biotic and abiotic drivers. A key achievement of this thesis is that it clarifies and confirms the importance of both biotic and abiotic interactions in arid resource-pulse environments. The trophic interaction model advances our knowledge on how interactions are context-specific and can change over space and time. It incorporates both bottom-up and top-down processes, and shows how the relative strength of these processes can change. I show also that simultaneous analysis of abiotic factors is important in predicting changes in species’ populations, and that biotic interactions (e.g. predation) can limit increases in consumer populations. In order to make accurate predictions about how species and ecological processes will respond to environmental change in arid systems, both biotic and abiotic factors need to be incorporated explicitly into models.