Rozprawy doktorskie na temat „Semi-arid zone”
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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.
Pełny tekst źródłaRamadan, 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/.
Pełny tekst źródłaJardine, 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.
Pełny tekst źródłaMulengera, Matthew Kagorobha. "Soil loss prediction in the semi-arid tropical savanna zone : a tool for soil conservation planning in Tanzania". Thesis, University of Newcastle Upon Tyne, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.318175.
Pełny tekst źródłaHarrington, 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.
Pełny tekst źródłaZapata-Rios, Xavier, Paul D. Brooks, Peter A. Troch, Jennifer McIntosh i Craig Rasmussen. "Influence of climate variability on water partitioning and effective energy and mass transfer in a semi-arid critical zone". COPERNICUS GESELLSCHAFT MBH, 2016. http://hdl.handle.net/10150/617370.
Pełny tekst źródłaDaamen, Carl Christopher. "Evaporation from sandy soils beneath crops in the semi-arid zone : a study of the use of microlysimeters and numerical simulation". Thesis, University of Reading, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.357138.
Pełny tekst źródłaBouragba, 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.
Pełny tekst źródłaThe 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.[...]
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.
Pełny tekst źródłaThe 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
Ibrahim, Ali Hano Abdelnasir. "Assessment of Impacts of Changes in Land Use Patterns on Land Degradation/Desertification in the Semi- arid Zone of White Nile State, Sudan, by Means of Remote Sensing and GIS". Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2014. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-157627.
Pełny tekst źródłaIm Sudan hat Land Degradation/ Desertifikation (LDD) weite Gegenden verwüstet, wobei hierbei soziale, wirtschaftliche und Umweltaspekte eine Rolle spielen. LDD wird von verschiedenen Faktoren ausgelöst, darunter Klimavariationen und menschliche Aktivitäten. Wahrscheinlich haben Landnutzungspraktiken und ihre Änderungen zu erhöhter LDD in der untersuchten Gegend beigetragen. Fernerkundungstechnologien sind sehr gute und weit entwickelte Werkzeuge um zeitliche und räumliche Informationen zur Erforschung von LDD und anderen Umweltaspekten zu ermitteln. Die Bestimmung von LDD und ihre Beziehung zur Änderung von Landnutzungsmustern (LUC) im raum-zeitlichen Maßstab ist bislang noch selten erforscht und ist ein Forschungsbereich, der für die semi-ariden Regionen des Sudan empfohlen wird. Die Studie wurde durchgeführt, um genaue und verbesserte raum-zeitliche Informationen zu gewinnen: um den Status der LDD von Vegetation und Boden zu bewerten, um den Einfluss des Landnutzungswandels auf LDD zu beurteilen und zu analysieren, und außerdem um die synergetischen Faktoren die den Landnutzungswandel und/oder LDD verursacht haben zu analysieren. Dabei wurde die semi-ariden Zone des Elgeteina Gebietes im Staat Weisser Nil (Sudan) während der vergangenen 36 Jahren unter Verwendung von geeigneter Fernerkundungs- und GIS-Technologie untersucht. Für die Studie wurden vier wolkenfreie Bilder von verschiedenen Sensoren (MSS 1973, TM 1986, ASTER 2009 and TM 2010) verwendet. Die Bilder wurden georeferenziert und radiometrische korrigiert, wobei die ENVI-FLAASH Software verwendet wurde. Anschließend wurden Teilgebiete des Untersuchungsgebietes mit einer Größe zwischen 1.600 und 2.000 Km2 ausgewählt. In der Studie fand der neue Ansatz der Integration von Vegetation und Boden Indizes und in-situ Daten Verwendung, um LDD zu bewerten. Ein Vergleich von pixel-basierter Bildanalyse (PBIA) und einem Ansatz von objekt-basierter Bildanalyse (OBIA) wurde durchgeführt, um die beste Methode der Kartierung von LUC und LDD ermitteln. Veränderungsmatrizen wurden eingesetzt, um räumlich-zeitlichen Änderungen der Landnutzung und Land Degradation abzuschätzen. Außerdem wurde ein Korrelation- und Modellierungs-Ansatz eingesetzt, um die klimatischen, sozioökonomischen und Fernerkundungsdaten zu verschmelzen und das Verhältnis zwischen den unterschiedlichen Faktoren zu bestimmen und um die Gründe für LUC und LDD zu analysieren aber auch um die Auswirkungen der Landnutzung auf LDD zu modellieren. Die Studie hat folgendes gezeigt: Die Änderungen der Landnutzungsmuster (RA, FWL and FML) fand in 1973 – 86 – 2009 statt und betraf sehr unterschiedliche Vegetationsmuster. Ebenso hatte die LUC Auswirkungen auf die Bodendegradation, was zu einer Verschiebung von Sanddünen im Zeitraum 1973-2009 führte. Landwirtschaft dominiert und hat starke Auswirkungen auf LDD, insbesondere auf die Degradation der Vegetationsbedeckung. Die Bevölkerungszunahme und der sozioökonomische Status der lokalen Bevölkerung sind die wesentlichen indirekten menschlichen Faktoren die verantwortlich für LUC und/oder LDD sind. SARVI ist etwas effizienter als NDVI, SAVI, ND4-25 und ND42-57, um den Zustand der Vegetation in semi-ariden Gebieten zu bestimmen, deshalb wurde dieser für die Studie ausgewählt. Es stellte sich heraus, dass der GSI hoch-effizient war, sowohl bei der Bestimmung der unterschiedlichen Typen von Bodendegradation als auch bei der Erstellung von Karten der obersten Bodenkorngröße, die bei der Bewertung der Landdegradation und Desertifikation half. OBIA-Fuzzy Logic Classification arbeitete dabei etwas genauer und effizienter als die PBIA-Hybrid Classification, um die Auswirkungen der Landnutzungsmuster auf LDD zu beurteilen. Als Fortsetzung der durchgeführten Arbeiten empfiehlt sich eine nochmalige Durchführung der Studie wobei anderes, hochaufgelöstes Bildmaterial und anspruchsvolle Software, wie eCognition und Feature Analyst (FA) verwendet werden sollten, um die Gültigkeit und Genauigkeit der Bewertungen und Modellierung des LU und LDD Status von Trockenland im Sudan zu beurteilen
Costa, Carlos Alexandre Gomes. "Soil moisture and water availability in the root zone under natural conditions of preserved Caatinga". Universidade Federal do CearÃ, 2012. http://www.teses.ufc.br/tde_busca/arquivo.php?codArquivo=8261.
Pełny tekst źródłaA Ãgua na bacia hidrogrÃfica està distribuÃda em diversos compartimentos importantes no que se refere à ecohidrologia. Muitos estudos em regiÃes semiÃridas apontam os reservatÃrios superficiais como principais compartimentos de Ãgua. Entretanto, a bacia hidrogrÃfica tem maior abrangÃncia que as bacias hidrÃulicas nela contida, e os recursos hÃdricos nos compartimentos distribuÃdos na bacia hidrogrÃfica (como no solo) devem ser analisados nÃo somente no que se refere aos usos ecolÃgicos, mas tambÃm como espaÃo de disponibilidade hÃdrica. Portanto, o objetivo do trabalho foi analisar, com base em medidas e modelagem, a dinÃmica da Ãgua nos solos de uma bacia semiÃrida de Caatinga preservada e seu impacto sobre a disponibilidade hÃdrica. Para isso foi medida, entre outros, a umidade do solo a cada hora, de 2003 a 2010 (2923 dias) na Bacia Experimental de Aiuaba (BEA, 12 kmÂ), totalmente preservada e com precipitaÃÃo mÃdia anual de 560 mm. O monitoramento foi realizado atravÃs de trÃs sensores TDR, um instalado em cada uma das trÃs associaÃÃes entre solo e vegetaÃÃo (SVA) identificadas na bacia. O mÃtodo de investigaÃÃo considerou seis etapas principais: i) determinaÃÃo da profundidade efetiva das raÃzes da Caatinga preservada; ii) calibraÃÃo dos sensores de umidade tipo TDR; iii) representaÃÃo espaÃo-temporal da umidade do solo em cada unidade de SVA; iv) anÃlise da disponibilidade hÃdrica do solo na zona das raÃzes; v) parametrizaÃÃo do modelo hidrolÃgico WASA-SED; e vi) parametrizaÃÃo do modelo hidrolÃgico DiCaSM. Os resultados obtidos nesta pesquisa indicam a importÃncia da abordagem da anÃlise temporal da umidade do solo e da disponibilidade hÃdrica do solo na zona das raÃzes para a manutenÃÃo do bioma Caatinga. Mais especificamente, foi observado que a profundidade efetiva do sistema radicular na BEA oscilou entre 70 e 80 cm nas regiÃes com solos profundos, porÃm, em regiÃes com solos rasos, observou-se que a profundidade efetiva das raÃzes adaptou-se Ãs restriÃÃes, ficando reduzida a menos de 40 cm. AlÃm disso, a anÃlise sazonal demonstrou que, na estaÃÃo de estio, as raÃzes tÃm comprimentos atà 11 cm menores, abrindo, portanto, poros secundÃrios que facilitarÃo a penetraÃÃo da Ãgua nas eventuais chuvas dos meses secos (junho a dezembro), assim como nas primeiras chuvas da estaÃÃo Ãmida. Nas duas SVAs cujos solos sÃo profundos e cuja vegetaÃÃo à densa, a Ãgua no solo encontra-se ânÃo-disponÃvelâ (isto Ã, abaixo do ponto de murcha permanente â WP) em quase nove meses ao ano (72% do tempo); e somente durante trÃs meses ao ano (25%) a Ãgua no solo encontra-se disponÃvel. Nos 3% restantes do ano (cerca de 10 dias) hà Ãgua gravitacional nessas SVAs. Na SVA cujo solo à raso e cuja vegetaÃÃo à esparsa, a dinÃmica da Ãgua no solo à diferente: o tempo em que hà Ãgua gravitacional, disponÃvel e nÃo disponÃvel à praticamente o mesmo (quatro meses ao ano). Isso se deve, entre outros, à baixa umidade do solo no ponto de murcha permanente do neossolo litÃlico; e à sua restrita espessura, gerando saturaÃÃo muito mais frequentemente que nos demais solos que â ao contrÃrio deste â dispÃem de drenagem profunda. A depleÃÃo da Ãgua no solo sob condiÃÃes de umidade abaixo do ponto de murcha foi outro resultado importante desta pesquisa. Nas duas associaÃÃes com solos profundos e vegetaÃÃo densa, observou-se â ao longo de todo o perÃodo investigado â decaimento contÃnuo da umidade atà que a mesma se aproximasse assintoticamente da umidade residual. AnÃlise mais detalhada demonstrou que a reduÃÃo da umidade do solo entre o WP e a umidade residual sempre obedecia ao decaimento exponencial. Na associaÃÃo com solo raso e vegetaÃÃo esparsa observou-se que a umidade nÃo caÃa para valores inferiores ao WP, mesmo sujeita ao mesmo rigor climÃtico das demais associaÃÃes. Considerando-se: (i) que em solo tÃo seco, a drenagem à improvÃvel; e (ii) que os processos associados de percolaÃÃo e evaporaÃÃo tampouco devam ser os responsÃveis pela retirada de Ãgua do solo (posto que o fenÃmeno nÃo se observa na SVA cujo solo à raso e, portanto, mais quente); levanta-se a hipÃtese que o secamento do solo nessas condiÃÃes deva ser causado por extraÃÃo de Ãgua pela vegetaÃÃo. Isso reforÃaria a tese de que a Caatinga dispÃe de adaptaÃÃo para sobreviver mesmo em condiÃÃes de estresse hÃdrico. Os modelos hidrolÃgicos WASA-SED e DiCaSM nÃo conseguiram representar adequadamente a dinÃmica temporal da Ãgua nos solos da BEA. No entanto, os modelos reproduziram satisfatoriamente as curvas de permanÃncia da umidade dos solos, permitindo representar a disponibilidade hÃdrica na zona das raÃzes para fins de planejamento. Por fim, logrou-se avaliar â quantitativa, espacial e temporalmente â a disponibilidade hÃdrica do solo. Esta à da mesma ordem de grandeza da disponibilidade de um reservatÃrio superficial Ãtimo. Em termos quantitativos, a disponibilidade no solo chega a ser quase cinco vezes superior à do reservatÃrio superficial, entretanto, a garantia associada da Ãgua superficial (90%) à bem superior à permanÃncia da Ãgua disponÃvel na BEA: apenas 28% nas Ãreas com solos profundos e 65% nas Ãreas com solos rasos.
Regarding ecohydrology, the catchment water is distributed over several important compartments. Many studies in semiarid re gions indicate the surface reservoirs as the main water compartments. However, the watershed has greater scope than the water reservoirs contained therein, and water resources in compartments distributed in the watershed (like in soil) should be analyzed not only with regard to ecological uses, but also as spaces of water availability. Therefore, the object ive of this work was to analyze, based on measurements and modeling, the water dynamics in th e soils of a semi-arid basin in preserved Caatinga, and its impact on water availability. Wit h this in mind, it was measured, among others, the soil moisture, every hour, from 2003 to 2010 (2923 days) in the Aiuaba Experimental Basin (AEB, 12 km Â), fully preserved and with average annual rainfall of 560 mm. Monitoring was carried out through three TDR se nsors, one installed in each of the three soil and vegetation associations (SVA) identified in the basin. The research method considered six main steps: i) assessment of the eff ective root depth of preserved Caatinga ii) calibration of humidity TDR sensors iii) space-time representation of soil moisture in each SVA unit iv) analysis of soil water availability in the root zone, v) parameterization of the WASA-SED hydrological model, and vi) parameterizati on of the DiCaSM hydrological model. The results of this research indicate the importance of addressing the temporal analysis of soil moisture and soil water availability in the root zone to maintain the Caatinga biome. More specifically, it was observed that the effecti ve depth of the root system on AEB ranged between 70 and 80 cm in areas with deep soils, but in areas with shallow soils, it was observed that the effective depth of the roots had adapted to the constraints, having been reduced to less than 40 cm. Furthermore, the season al analysis showed that in the dry season, the roots have lengths up to 11 cm smaller, openin g, therefore, secondary pores that facilitate the penetration of what little rain water falls in the dry months (June-December), as well as in the first rains of the wet season. In the two SVAs whose soils are deep and the vegetation is dense, the soil water is 'not available' (ie below the permanent wilting point - WP) during nearly nine months a year (72% of the time), and on ly during three months of the year (25% of the time) the soil water is available. In the re maining 3% of the year (about 10 days) there is gravitational water in these SVAs. In the SVAs whose soil is shallow and whose vegetation is sparse, the dynamics of soil water are different : the time when there is gravitational water, available and unavailable, is practically the same (four months a year). This is due to, among other things, the low soil moisture at the permanen t wilting point of the Udorthent, and to its limited thickness, generating saturation much more frequently than in others that - unlike this one - have deep drainage. The depletion of soil wat er under conditions of moisture below the wilting point was another important result of this research. In the two associations with deep soils and thick vegetation, it was observed â throu ghout the observation period â continuous fall of moisture level until it approached asymptot ically the residual moisture. More detailed analysis showed that the reduction of soil moisture between the WP and the residual moisture level always followed the exponential decay. It was observed, in the association of shallow soil and sparse vegetation, that the moisture did not fall to below the WP, even subjected to the same rigorous climate of the other associations . Considering: (i) that in such a dry soil, the drainage is unlikely, and (ii) that the associated processes of percolation and evaporation should not be responsible for the removal of soil w ater either (since the phenomenon is not observed in SVAs whose soil is shallow and therefor e warmer) , it is raised the hypothesis that the soil drying under these conditions must be caused by water extraction by vegetation. This would strengthen the argument that the Caating a has adapted to survive under water stress. The hydrological models WASA-SED and DiCaSM failed to adequately represent the temporal dynamics of soil water in the AEB. However , the models did satisfactorily reproduce the retention curves of soil moisture, al lowing the representation of the water availability in the root zone for planning purposes . Finally, we managed to evaluate - quantitatively, spatially and temporally â the soil water availability. This availability is of the same order of magnitude of the availability of an o ptimal surface reservoir. The availability in the soil, in quantitative terms, can be almost five times higher than that of the surface reservoir. However, the security associated with su rface water (90%) is much higher than the water permanence available in the AEB: just 28% in areas with deep soils and 65% in areas with shallow soils.
Diallo, Mamadou. "Problemes economiques de la maitrise de l'eau dans le sahel : le cas des petits perimetres irrigues avec l'eau souterraine". Paris, ENMP, 1988. http://www.theses.fr/1988ENMP0123.
Pełny tekst źródłaIbrahim, Ali Hano Abdelnasir [Verfasser], Elmar [Akademischer Betreuer] Csaplovics, Mubark [Akademischer Betreuer] Abdelrahman i Hannelore [Akademischer Betreuer] Kusserow. "Assessment of Impacts of Changes in Land Use Patterns on Land Degradation/Desertification in the Semi- arid Zone of White Nile State, Sudan, by Means of Remote Sensing and GIS / Abdelnasir Ibrahim Ali Hano. Gutachter: Elmar Csaplovics ; Mubark Abdelrahman ; Hannelore Kusserow". Dresden : Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2014. http://d-nb.info/1069092118/34.
Pełny tekst źródłaAralova, Dildora, Kristina Toderich, Ben Jarihani, Dilshod Gafurov, Liliya Gismatulina, Babatunde A. Osunmadewa i 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.
Pełny tekst źródłaRehman, 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.
Pełny tekst źródłaLima, 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
Mendonça, Ariadne Aguiar Vitório. "Caracterização tipológica das queijarias artesanais na zona rural do município de Major Izidoro no semi-árido de Alagoas". Universidade Federal de Alagoas, 2009. http://repositorio.ufal.br/handle/riufal/698.
Pełny tekst źródłaA região semi-árida do nordeste brasileiro é uma região marcada pelas dificuldades climática e social desde o período da colonização e tem como atividade produtiva tradicional a fabricação dos queijos de coalho e de manteiga. Este trabalho surgiu das indagações a respeito das alterações na estrutura física das queijarias artesanais, decorrentes principalmente, das exigências às normas que tratam da higiene e segurança alimentar sobre os produtos lácteos. Tem como objetivo identificar as categorias tipológicas e relacioná-las ao modo de produção das queijarias artesanais de queijo de coalho e de queijo de manteiga, verificando o atendimento as regulamentações. A caracterização da arquitetura rural fundamentou-se na conexão entre o ambiente construído, a atividade produtiva e a cultura, no esforço de identificarem-se as especificidades construtivas ao nível local. Teve como base teórica, o modelo denominado de co-evolução. A pesquisa de campo ocorreu em onze propriedades rurais queijeiras do município de Major Izidoro, Alagoas, mediante levantamento físico e fotográfico, subsidiando a investigação dos vetores produtivo e espacial. Utilizaram-se como critérios os itens da norma (BPF). Classificou-se as tipologias arquitetônicas das queijarias em três grupos: o tradicional (fabriqueta), intermediário (fabriqueta ou laticínio) e industrial (laticínio), com respeito à parte interna e externa da propriedade, composição e organização. Quanto ao aspecto produtivo, considerou-se que os tipos de queijo são decorrentes dos diferentes processos de fabricação. O tema multidisciplinar sugere pesquisas nas áreas sociais e na arquitetura, podendo explorar mais queijarias tanto no estado de Alagoas, quanto em outras regiões do Nordeste.
Costa, Carlos Alexandre Gomes. "Umidade do solo e disponibilidade hídrica na zona das raízes em condições naturais de caatinga preservada". reponame:Repositório Institucional da UFC, 2012. http://www.repositorio.ufc.br/handle/riufc/18822.
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Regarding ecohydrology, the catchment water is distributed over several important compartments. Many studies in semiarid re gions indicate the surface reservoirs as the main water compartments. However, the watershed has greater scope than the water reservoirs contained therein, and water resources in compartments distributed in the watershed (like in soil) should be analyzed not only with regard to ecological uses, but also as spaces of water availability. Therefore, the object ive of this work was to analyze, based on measurements and modeling, the water dynamics in th e soils of a semi-arid basin in preserved Caatinga, and its impact on water availability. Wit h this in mind, it was measured, among others, the soil moisture, every hour, from 2003 to 2010 (2923 days) in the Aiuaba Experimental Basin (AEB, 12 km ²), fully preserved and with average annual rainfall of 560 mm. Monitoring was carried out through three TDR se nsors, one installed in each of the three soil and vegetation associations (SVA) identified in the basin. The research method considered six main steps: i) assessment of the eff ective root depth of preserved Caatinga ii) calibration of humidity TDR sensors iii) space-time representation of soil moisture in each SVA unit iv) analysis of soil water availability in the root zone, v) parameterization of the WASA-SED hydrological model, and vi) parameterizati on of the DiCaSM hydrological model. The results of this research indicate the importance of addressing the temporal analysis of soil moisture and soil water availability in the root zone to maintain the Caatinga biome. More specifically, it was observed that the effecti ve depth of the root system on AEB ranged between 70 and 80 cm in areas with deep soils, but in areas with shallow soils, it was observed that the effective depth of the roots had adapted to the constraints, having been reduced to less than 40 cm. Furthermore, the season al analysis showed that in the dry season, the roots have lengths up to 11 cm smaller, openin g, therefore, secondary pores that facilitate the penetration of what little rain water falls in the dry months (June-December), as well as in the first rains of the wet season. In the two SVAs whose soils are deep and the vegetation is dense, the soil water is 'not available' (ie below the permanent wilting point - WP) during nearly nine months a year (72% of the time), and on ly during three months of the year (25% of the time) the soil water is available. In the re maining 3% of the year (about 10 days) there is gravitational water in these SVAs. In the SVAs whose soil is shallow and whose vegetation is sparse, the dynamics of soil water are different : the time when there is gravitational water, available and unavailable, is practically the same (four months a year). This is due to, among other things, the low soil moisture at the permanen t wilting point of the Udorthent, and to its limited thickness, generating saturation much more frequently than in others that - unlike this one - have deep drainage. The depletion of soil wat er under conditions of moisture below the wilting point was another important result of this research. In the two associations with deep soils and thick vegetation, it was observed – throu ghout the observation period – continuous fall of moisture level until it approached asymptot ically the residual moisture. More detailed analysis showed that the reduction of soil moisture between the WP and the residual moisture level always followed the exponential decay. It was observed, in the association of shallow soil and sparse vegetation, that the moisture did not fall to below the WP, even subjected to the same rigorous climate of the other associations . Considering: (i) that in such a dry soil, the drainage is unlikely, and (ii) that the associated processes of percolation and evaporation should not be responsible for the removal of soil w ater either (since the phenomenon is not observed in SVAs whose soil is shallow and therefor e warmer) , it is raised the hypothesis that the soil drying under these conditions must be caused by water extraction by vegetation. This would strengthen the argument that the Caating a has adapted to survive under water stress. The hydrological models WASA-SED and DiCaSM failed to adequately represent the temporal dynamics of soil water in the AEB. However , the models did satisfactorily reproduce the retention curves of soil moisture, al lowing the representation of the water availability in the root zone for planning purposes . Finally, we managed to evaluate - quantitatively, spatially and temporally – the soil water availability. This availability is of the same order of magnitude of the availability of an o ptimal surface reservoir. The availability in the soil, in quantitative terms, can be almost five times higher than that of the surface reservoir. However, the security associated with su rface water (90%) is much higher than the water permanence available in the AEB: just 28% in areas with deep soils and 65% in areas with shallow soils.
A água na bacia hidrográfica está distribuída em diversos compartimentos importantes no que se refere à ecohidrologia. Muitos estudos em regiões semiáridas apontam os reservatórios superficiais como principais compartimentos de água. Entretanto, a bacia hidrográfica tem maior abrangência que as bacias hidráulicas nela contida, e os recursos hídricos nos compartimentos distribuídos na bacia hidrográfica (como no solo) devem ser analisados não somente no que se refere aos usos ecológicos, mas também como espaço de disponibilidade hídrica. Portanto, o objetivo do trabalho foi analisar, com base em medidas e modelagem, a dinâmica da água nos solos de uma bacia semiárida de Caatinga preservada e seu impacto sobre a disponibilidade hídrica. Para isso foi medida, entre outros, a umidade do solo a cada hora, de 2003 a 2010 (2923 dias) na Bacia Experimental de Aiuaba (BEA, 12 km²), totalmente preservada e com precipitação média anual de 560 mm. O monitoramento foi realizado através de três sensores TDR, um instalado em cada uma das três associações entre solo e vegetação (SVA) identificadas na bacia. O método de investigação considerou seis etapas principais: i) determinação da profundidade efetiva das raízes da Caatinga preservada; ii) calibração dos sensores de umidade tipo TDR; iii) representação espaço-temporal da umidade do solo em cada unidade de SVA; iv) análise da disponibilidade hídrica do solo na zona das raízes; v) parametrização do modelo hidrológico WASA-SED; e vi) parametrização do modelo hidrológico DiCaSM. Os resultados obtidos nesta pesquisa indicam a importância da abordagem da análise temporal da umidade do solo e da disponibilidade hídrica do solo na zona das raízes para a manutenção do bioma Caatinga. Mais especificamente, foi observado que a profundidade efetiva do sistema radicular na BEA oscilou entre 70 e 80 cm nas regiões com solos profundos, porém, em regiões com solos rasos, observou-se que a profundidade efetiva das raízes adaptou-se às restrições, ficando reduzida a menos de 40 cm. Além disso, a análise sazonal demonstrou que, na estação de estio, as raízes têm comprimentos até 11 cm menores, abrindo, portanto, poros secundários que facilitarão a penetração da água nas eventuais chuvas dos meses secos (junho a dezembro), assim como nas primeiras chuvas da estação úmida. Nas duas SVAs cujos solos são profundos e cuja vegetação é densa, a água no solo encontra-se ‘não-disponível’ (isto é, abaixo do ponto de murcha permanente – WP) em quase nove meses ao ano (72% do tempo); e somente durante três meses ao ano (25%) a água no solo encontra-se disponível. Nos 3% restantes do ano (cerca de 10 dias) há água gravitacional nessas SVAs. Na SVA cujo solo é raso e cuja vegetação é esparsa, a dinâmica da água no solo é diferente: o tempo em que há água gravitacional, disponível e não disponível é praticamente o mesmo (quatro meses ao ano). Isso se deve, entre outros, à baixa umidade do solo no ponto de murcha permanente do neossolo litólico; e à sua restrita espessura, gerando saturação muito mais frequentemente que nos demais solos que – ao contrário deste – dispõem de drenagem profunda. A depleção da água no solo sob condições de umidade abaixo do ponto de murcha foi outro resultado importante desta pesquisa. Nas duas associações com solos profundos e vegetação densa, observou-se – ao longo de todo o período investigado – decaimento contínuo da umidade até que a mesma se aproximasse assintoticamente da umidade residual. Análise mais detalhada demonstrou que a redução da umidade do solo entre o WP e a umidade residual sempre obedecia ao decaimento exponencial. Na associação com solo raso e vegetação esparsa observou-se que a umidade não caía para valores inferiores ao WP, mesmo sujeita ao mesmo rigor climático das demais associações. Considerando-se: (i) que em solo tão seco, a drenagem é improvável; e (ii) que os processos associados de percolação e evaporação tampouco devam ser os responsáveis pela retirada de água do solo (posto que o fenômeno não se observa na SVA cujo solo é raso e, portanto, mais quente); levanta-se a hipótese que o secamento do solo nessas condições deva ser causado por extração de água pela vegetação. Isso reforçaria a tese de que a Caatinga dispõe de adaptação para sobreviver mesmo em condições de estresse hídrico. Os modelos hidrológicos WASA-SED e DiCaSM não conseguiram representar adequadamente a dinâmica temporal da água nos solos da BEA. No entanto, os modelos reproduziram satisfatoriamente as curvas de permanência da umidade dos solos, permitindo representar a disponibilidade hídrica na zona das raízes para fins de planejamento. Por fim, logrou-se avaliar – quantitativa, espacial e temporalmente – a disponibilidade hídrica do solo. Esta é da mesma ordem de grandeza da disponibilidade de um reservatório superficial ótimo. Em termos quantitativos, a disponibilidade no solo chega a ser quase cinco vezes superior à do reservatório superficial, entretanto, a garantia associada da água superficial (90%) é bem superior à permanência da água disponível na BEA: apenas 28% nas áreas com solos profundos e 65% nas áreas com solos rasos.
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.
Pełny tekst źródłaIn 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
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.
Pełny tekst źródłaAtkinson, Victoria. "Mine and industrial site revegetation in the semi-arid zone, North-Eastern Eyre Peninsula, South Australia". 2005. http://arrow.unisa.edu.au:8081/1959.8/46701.
Pełny tekst źródłaTanji, Abbes. "On-farm evaluation of wheat production as affected by three weeding systems and top-dressed nitrogen in Chaouia (semi-arid zone of Morocco)". 1987. http://hdl.handle.net/2097/22228.
Pełny tekst źródłaIbrahim, Ali Hano Abdelnasir. "Assessment of Impacts of Changes in Land Use Patterns on Land Degradation/Desertification in the Semi- arid Zone of White Nile State, Sudan, by Means of Remote Sensing and GIS". Doctoral thesis, 2013. https://tud.qucosa.de/id/qucosa%3A28451.
Pełny tekst źródłaIm Sudan hat Land Degradation/ Desertifikation (LDD) weite Gegenden verwüstet, wobei hierbei soziale, wirtschaftliche und Umweltaspekte eine Rolle spielen. LDD wird von verschiedenen Faktoren ausgelöst, darunter Klimavariationen und menschliche Aktivitäten. Wahrscheinlich haben Landnutzungspraktiken und ihre Änderungen zu erhöhter LDD in der untersuchten Gegend beigetragen. Fernerkundungstechnologien sind sehr gute und weit entwickelte Werkzeuge um zeitliche und räumliche Informationen zur Erforschung von LDD und anderen Umweltaspekten zu ermitteln. Die Bestimmung von LDD und ihre Beziehung zur Änderung von Landnutzungsmustern (LUC) im raum-zeitlichen Maßstab ist bislang noch selten erforscht und ist ein Forschungsbereich, der für die semi-ariden Regionen des Sudan empfohlen wird. Die Studie wurde durchgeführt, um genaue und verbesserte raum-zeitliche Informationen zu gewinnen: um den Status der LDD von Vegetation und Boden zu bewerten, um den Einfluss des Landnutzungswandels auf LDD zu beurteilen und zu analysieren, und außerdem um die synergetischen Faktoren die den Landnutzungswandel und/oder LDD verursacht haben zu analysieren. Dabei wurde die semi-ariden Zone des Elgeteina Gebietes im Staat Weisser Nil (Sudan) während der vergangenen 36 Jahren unter Verwendung von geeigneter Fernerkundungs- und GIS-Technologie untersucht. Für die Studie wurden vier wolkenfreie Bilder von verschiedenen Sensoren (MSS 1973, TM 1986, ASTER 2009 and TM 2010) verwendet. Die Bilder wurden georeferenziert und radiometrische korrigiert, wobei die ENVI-FLAASH Software verwendet wurde. Anschließend wurden Teilgebiete des Untersuchungsgebietes mit einer Größe zwischen 1.600 und 2.000 Km2 ausgewählt. In der Studie fand der neue Ansatz der Integration von Vegetation und Boden Indizes und in-situ Daten Verwendung, um LDD zu bewerten. Ein Vergleich von pixel-basierter Bildanalyse (PBIA) und einem Ansatz von objekt-basierter Bildanalyse (OBIA) wurde durchgeführt, um die beste Methode der Kartierung von LUC und LDD ermitteln. Veränderungsmatrizen wurden eingesetzt, um räumlich-zeitlichen Änderungen der Landnutzung und Land Degradation abzuschätzen. Außerdem wurde ein Korrelation- und Modellierungs-Ansatz eingesetzt, um die klimatischen, sozioökonomischen und Fernerkundungsdaten zu verschmelzen und das Verhältnis zwischen den unterschiedlichen Faktoren zu bestimmen und um die Gründe für LUC und LDD zu analysieren aber auch um die Auswirkungen der Landnutzung auf LDD zu modellieren. Die Studie hat folgendes gezeigt: Die Änderungen der Landnutzungsmuster (RA, FWL and FML) fand in 1973 – 86 – 2009 statt und betraf sehr unterschiedliche Vegetationsmuster. Ebenso hatte die LUC Auswirkungen auf die Bodendegradation, was zu einer Verschiebung von Sanddünen im Zeitraum 1973-2009 führte. Landwirtschaft dominiert und hat starke Auswirkungen auf LDD, insbesondere auf die Degradation der Vegetationsbedeckung. Die Bevölkerungszunahme und der sozioökonomische Status der lokalen Bevölkerung sind die wesentlichen indirekten menschlichen Faktoren die verantwortlich für LUC und/oder LDD sind. SARVI ist etwas effizienter als NDVI, SAVI, ND4-25 und ND42-57, um den Zustand der Vegetation in semi-ariden Gebieten zu bestimmen, deshalb wurde dieser für die Studie ausgewählt. Es stellte sich heraus, dass der GSI hoch-effizient war, sowohl bei der Bestimmung der unterschiedlichen Typen von Bodendegradation als auch bei der Erstellung von Karten der obersten Bodenkorngröße, die bei der Bewertung der Landdegradation und Desertifikation half. OBIA-Fuzzy Logic Classification arbeitete dabei etwas genauer und effizienter als die PBIA-Hybrid Classification, um die Auswirkungen der Landnutzungsmuster auf LDD zu beurteilen. Als Fortsetzung der durchgeführten Arbeiten empfiehlt sich eine nochmalige Durchführung der Studie wobei anderes, hochaufgelöstes Bildmaterial und anspruchsvolle Software, wie eCognition und Feature Analyst (FA) verwendet werden sollten, um die Gültigkeit und Genauigkeit der Bewertungen und Modellierung des LU und LDD Status von Trockenland im Sudan zu beurteilen.
Gayler, Lucyna Maria. "A palaeoenvironmental history of the Paroo and Warrego Regions, Australia: a multi-proxy, multi-site approach". Thesis, 2008. http://hdl.handle.net/1959.13/33470.
Pełny tekst źródłaThe records of environmental change in Australia’s arid zone can be greatly enriched by employing a multi-proxy approach and landscape-scale analysis. This research uses these tools to construct a palaeoenvironmental history of the Paroo/Warrego Region. While the Region’s flow regimes and water balances are characterised by medium-term (decadal) variability (Young, 1999), its hydrological records are inadequately brief. Subsequently, land and water management decisions are based on short term data, risking irreversible damage, desertification or loss of diversity. A better understanding of this highly dynamic landscape can thus improve the land and resource management outcomes. While dating was constrained by a lack of funds, the Paroo/Warrego history reconstructed from fluvial and aeolian deposits correlated well with events recorded from other inland regions of the Australian continent. In summary, this new research provided evidence of high lake water levels prior to the Last Glacial. The extreme aridity at the onset of Last Glacial caused long term drying of the lakes and mobilisation of the red sand dunes. In latter stages of the glacial phase the aridity gave way to periodic fluctuations between flood and drought events that probably lasted until 16 000 - 14 000 BP. The new climatic regime resulted in formation of gypsum lunettes and later, following reduction in gypsum supply, clay lunettes. The orientation of red sand dunes and lunettes indicates a more northerly extent of the westerlies than in modern times. Around the late Pleistocene-early Holocene boundary the climate became more stable and wetter, but still somewhat drier than during the pre-Last Glacial lacustrine phase. As a result, the region’s lakes reverted to a permanent and semi-permanent status. A strong aridity signal, comparable to the semi-regular droughts of the Last Glacial, was recorded in the Paroo/Warrego lakes during the late 1890s-1940s period of below average rainfall. It was followed by 50 years of wetter conditions with two extremely wet phases in the 1950s and the 1970s. Finally, the most recent records suggest a new drying trend. The semi-arid vegetation appears to have adapted to climate variability, with herbs and grasses expanding with the onset of wet conditions before being replaced by Chenopodiaceae as the landscape started to dry. The fresher lake basins and water courses were likely to provide refuge during prolonged arid phases and dispersal foci during intervening wetter periods, thus enabling greater flexibility in response to changes and enhancing resilience. The European land use interfered with the natural cycles and balances, leading to decrease in ground cover, suppression of fire, increase in runoff and catchment erosion, acceleration of sediment accumulation rates in wetlands, resulting in decline of their water holding capacity, and expansion of woody vegetation. The research improved the processing protocols, reference databases, and transfer of methods to enable greater sample processing efficiency and improve results. The use of multiple proxies (including biotic and abiotic components) and sites, as well as different depositional features, provided access to a broader picture of environmental change than was previously possible. It also facilitated multi-scale resolution, allowing discrimination between localised responses of individual lakes and regional trends. The full value of this research will come from informing natural resource managers, whose actions will shape the future landscapes of the Paroo and Warrego Region.
Gayler, Lucyna Maria. "A palaeoenvironmental history of the Paroo and Warrego Regions, Australia: a multi-proxy, multi-site approach". 2008. http://hdl.handle.net/1959.13/33470.
Pełny tekst źródłaThe records of environmental change in Australia’s arid zone can be greatly enriched by employing a multi-proxy approach and landscape-scale analysis. This research uses these tools to construct a palaeoenvironmental history of the Paroo/Warrego Region. While the Region’s flow regimes and water balances are characterised by medium-term (decadal) variability (Young, 1999), its hydrological records are inadequately brief. Subsequently, land and water management decisions are based on short term data, risking irreversible damage, desertification or loss of diversity. A better understanding of this highly dynamic landscape can thus improve the land and resource management outcomes. While dating was constrained by a lack of funds, the Paroo/Warrego history reconstructed from fluvial and aeolian deposits correlated well with events recorded from other inland regions of the Australian continent. In summary, this new research provided evidence of high lake water levels prior to the Last Glacial. The extreme aridity at the onset of Last Glacial caused long term drying of the lakes and mobilisation of the red sand dunes. In latter stages of the glacial phase the aridity gave way to periodic fluctuations between flood and drought events that probably lasted until 16 000 - 14 000 BP. The new climatic regime resulted in formation of gypsum lunettes and later, following reduction in gypsum supply, clay lunettes. The orientation of red sand dunes and lunettes indicates a more northerly extent of the westerlies than in modern times. Around the late Pleistocene-early Holocene boundary the climate became more stable and wetter, but still somewhat drier than during the pre-Last Glacial lacustrine phase. As a result, the region’s lakes reverted to a permanent and semi-permanent status. A strong aridity signal, comparable to the semi-regular droughts of the Last Glacial, was recorded in the Paroo/Warrego lakes during the late 1890s-1940s period of below average rainfall. It was followed by 50 years of wetter conditions with two extremely wet phases in the 1950s and the 1970s. Finally, the most recent records suggest a new drying trend. The semi-arid vegetation appears to have adapted to climate variability, with herbs and grasses expanding with the onset of wet conditions before being replaced by Chenopodiaceae as the landscape started to dry. The fresher lake basins and water courses were likely to provide refuge during prolonged arid phases and dispersal foci during intervening wetter periods, thus enabling greater flexibility in response to changes and enhancing resilience. The European land use interfered with the natural cycles and balances, leading to decrease in ground cover, suppression of fire, increase in runoff and catchment erosion, acceleration of sediment accumulation rates in wetlands, resulting in decline of their water holding capacity, and expansion of woody vegetation. The research improved the processing protocols, reference databases, and transfer of methods to enable greater sample processing efficiency and improve results. The use of multiple proxies (including biotic and abiotic components) and sites, as well as different depositional features, provided access to a broader picture of environmental change than was previously possible. It also facilitated multi-scale resolution, allowing discrimination between localised responses of individual lakes and regional trends. The full value of this research will come from informing natural resource managers, whose actions will shape the future landscapes of the Paroo and Warrego Region.
Nketia, Kwabena Abrefa. "Space-time modelling of seasonal soil moisture for improved crop production – the case of the Guinea savannah region, Ghana". Thesis, 2020. http://hdl.handle.net/21.11130/00-1735-0000-0005-1527-8.
Pełny tekst źródłaStenhouse, Gulperi. "Malleefowl and anthropogenic change: an integrated analysis of population trends, landscape genetics and movement ecology". Thesis, 2022. https://hdl.handle.net/2440/135973.
Pełny tekst źródłaThesis (Ph.D.) -- University of Adelaide, School of Biological Sciences, 2022
Weiss, Tomáš. "Model transportu látek v nesaturované zóně ve vertisolech v semiaridním klimatu". Master's thesis, 2015. http://www.nusl.cz/ntk/nusl-331208.
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