Dissertations / Theses on the topic 'Semi-arid zone'

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.

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)

The critical zone (CZ) is the heterogeneous, near-surface layer of the planet that regulates life-sustaining resources. Previous research has demonstrated that a quantification of the influxes of effective energy and mass transfer (EEMT) to the CZ can predict its structure and function. In this study, we quantify how climate variability in the last 3 decades (1984–2012) has affected water availability and the temporal trends in EEMT. This study takes place in the 1200 km² upper Jemez River basin in northern New Mexico. The analysis of climate, water availability, and EEMT was based on records from two high-elevation SNOTEL stations, PRISM data, catchment-scale discharge, and satellite-derived net primary productivity (MODIS). Results from this study indicated a decreasing trend in water availability, a reduction in forest productivity (4 g C m⁻² per 10 mm of reduction in precipitation), and decreasing EEMT (1.2–1.3 MJ m² decade⁻¹). Although we do not know the timescales of CZ change, these results suggest an upward migration of CZ/ecosystem structure on the order of 100 m decade⁻¹, and that decadal-scale differences in EEMT are similar to the differences between convergent/hydrologically subsidized and planar/divergent landscapes, which have been shown to be very different in vegetation and CZ structure.

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.[...]

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.1479
The 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

In Sudan, land degradation/desertification (LDD) has devastated large areas and consequently, it includes social, economic, and environmental aspects. LDD results from various factors, including climatic variation and human activities. Probably the LU practices and their changes have contributed to an increase of LDD in that area. Remote sensing technology has become unique and developed tool for providing temporal and spatial information for the LDD research and other environmental aspects. Determination of LDD and its relationship to land use pattern change (LUC) at spatiotemporal scale is rare, critical issue, and is one of the recommended research in semi-arid regions of Sudan. The study was carried out to derive accurate and improved spatiotemporal information: to assess the status of land LDD of vegetation and soil, to assess and model influences of the LUC on LDD, and moreover to analyse the synergistic factors that have caused the land use change and/or LDD in semi- arid zone of Elgeteina Locality in While Nile State, Sudan during the last 36 years, using appropriate remote sensing (RS) and GIS technology. The study used four-cloud free images of different sensors (MSS 1973, TM 1986, ASTER 2009 and TM 2010). The imageries were Geo-referenced and radiometrically corrected by using ENVI-FLAASH software. Then subsets of the study area were taken, ranging from 1600-2000 Km2. The study applied the new approach of integration between vegetation and soil indices and in situ data to assess the LDD. Comparison between pixel based image analysis (PBIA) and latterly approach of object based image analysis (OBIA) was done by selecting the best one for mapping LUC and LDD accurately. The change detection - matrix was applied to estimate the spatiotemporal of changes in land use and land degradation. Moreover, correlation and model approach was employed for fusing the climatic, socioeconomic and remote sensing data to determine the relationships between the different factors and to analyse the reasons for the LUC and LDD as well as for modelling LU effects on LDD. The study revealed that: The changes in land use patterns (RA, FWL and FML) took place in 1973 – 86 – 2009, and affecting thoroughly different patterns of the vegetation cover. Likewise the LUC affected soil degradation which led to the movement of sand dunes in 1973 – 2009. The agricultural activity is the dominant and has more effect on LDD particularly on the vegetation cover degradation. The population growth and the socioeconomic status of local people are the main indirect human inducing factors responsible for LUC and/or LDD. SARVI is slightly more efficient than NDVI, SAVI, ND4-25 and ND42-57, for detecting the vegetation status in semi-arid area, therefore the study selected it for the assessment. GSI proved highly efficient in determining the different types of soil degradation, and in producing the map of top soil grain size, which assisted in the assessment of land degradation and desertification. OBIA-fuzzy logic classification performed better than the PBIA- hybrid classification for assessing LU patterns impact on LDD. The study recommends to: replication of this study by using different imagery with high resolutions and sophisticated software, such as eCognition and Feature Analyst (FA) for increasing the validity and accuracy of the assessment and modelling of LU patterns and LDD status in dry land is important in the Sudan
Im 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

Conselho Nacional de Desenvolvimento CientÃfico e TecnolÃgico
A 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.

Cette etude cherche a determiner sous quelles conditions economiques l'eau souterraine peut etre utilisee a des fins agricoles dans le sahel. Auparavant on a cherche a definir la place de l'eau dans la crise de l'agriculture. Puis on a examine le role que l'eau souterraine peut jouer dans la resolution de cette crise

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.

Submitted by GÉSSICA SILVA LIMA null (gessicaslima@hotmail.com) on 2016-11-24T20:13:59Z No. of bitstreams: 1 Tese_Géssica Silva Lima.pdf: 1381711 bytes, checksum: 9da4409253a7ea1d9b0f0f18bfdcb292 (MD5)
Approved for entry into archive by Felipe Augusto Arakaki (arakaki@reitoria.unesp.br) on 2016-11-29T13:12:51Z (GMT) No. of bitstreams: 1 lima_gs_dr_bot.pdf: 1381711 bytes, checksum: 9da4409253a7ea1d9b0f0f18bfdcb292 (MD5)
Made available in DSpace on 2016-11-29T13:12:51Z (GMT). No. of bitstreams: 1 lima_gs_dr_bot.pdf: 1381711 bytes, checksum: 9da4409253a7ea1d9b0f0f18bfdcb292 (MD5) Previous issue date: 2016-09-29
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

The semi-arid region of the Northeast of Brazil is a place known for its climactic and social difficulties since the colonization period and its main activity is the production of cheese ( queijo coalho and queijo manteiga ). This work is the result of the changes on the structure of the handcrafted cheese factories, especially because of the demanding of the rules concerning hygiene and food safety on dairy products. Its main goal is to identify the typological categories and relate them to the way the handcrafted cheese is made ( queijo coalho and queijo manteiga ), according to the regulations. The rural architecture was based on the connection between the environment built, the productive activity and the culture, in an effort to identify the constructive specificities of the local level. The model called co-evolução was used as the theoretical base. The field research was done in eleven rural cheese properties in the town of Major Izidoro, Alagoas, using physical and photographic data, subsidizing the investigation of productive and spatial. The criteria used were based on the rules of the (BPF). The architectonic cheese typologies were classified in three groups: the traditional (handcrafted cheese), the intermediate (handcrafted cheese or dairy) and the industrial (dairy), in relation to the inside and outside of the property, its composition and its organization. When it comes to the productive aspect, it was taken into consideration that the types of cheese are due to different processes in fabrication. The multidisciplinary theme suggests researches in social areas and in architecture, and it may explore more cheese factories in the state of Alagoas as in other regions of the Northeast.
A 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, Alexandre Gomes da. Umidade do solo e disponibilidade hídrica na zona das raízes em condições naturais de caatinga preservada. 2012. 182 f. : Tese (doutorado) - Universidade Federal do Ceará, Centro de Ciências Agrárias, Departamento de Engenharia Agrícola, Programa de Pós-Graduação em Engenharia Agrícola, 2012. Fortaleza-CE, 2012.
Submitted by demia Maia (demiamlm@gmail.com) on 2016-08-02T16:07:05Z No. of bitstreams: 1 2012_tese_cagcosta.pdf: 15315410 bytes, checksum: 38127bb5784afef6034c271f1422f7b4 (MD5)
Approved for entry into archive by demia Maia (demiamlm@gmail.com) on 2016-08-02T16:07:38Z (GMT) No. of bitstreams: 1 2012_tese_cagcosta.pdf: 15315410 bytes, checksum: 38127bb5784afef6034c271f1422f7b4 (MD5)
Made available in DSpace on 2016-08-02T16:07:38Z (GMT). No. of bitstreams: 1 2012_tese_cagcosta.pdf: 15315410 bytes, checksum: 38127bb5784afef6034c271f1422f7b4 (MD5) Previous issue date: 2012
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.

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 sols
In 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

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

This research aims to develop the present knowledge of arid zone rehabilitation by scientifically testing topsoiling and seeding treatments on the Eyre Peninsula, South Australia, in a way that enables the widest application and comparison to other mining leases throughout the arid lands.

In Sudan, land degradation/desertification (LDD) has devastated large areas and consequently, it includes social, economic, and environmental aspects. LDD results from various factors, including climatic variation and human activities. Probably the LU practices and their changes have contributed to an increase of LDD in that area. Remote sensing technology has become unique and developed tool for providing temporal and spatial information for the LDD research and other environmental aspects. Determination of LDD and its relationship to land use pattern change (LUC) at spatiotemporal scale is rare, critical issue, and is one of the recommended research in semi-arid regions of Sudan. The study was carried out to derive accurate and improved spatiotemporal information: to assess the status of land LDD of vegetation and soil, to assess and model influences of the LUC on LDD, and moreover to analyse the synergistic factors that have caused the land use change and/or LDD in semi- arid zone of Elgeteina Locality in While Nile State, Sudan during the last 36 years, using appropriate remote sensing (RS) and GIS technology. The study used four-cloud free images of different sensors (MSS 1973, TM 1986, ASTER 2009 and TM 2010). The imageries were Geo-referenced and radiometrically corrected by using ENVI-FLAASH software. Then subsets of the study area were taken, ranging from 1600-2000 Km2. The study applied the new approach of integration between vegetation and soil indices and in situ data to assess the LDD. Comparison between pixel based image analysis (PBIA) and latterly approach of object based image analysis (OBIA) was done by selecting the best one for mapping LUC and LDD accurately. The change detection - matrix was applied to estimate the spatiotemporal of changes in land use and land degradation. Moreover, correlation and model approach was employed for fusing the climatic, socioeconomic and remote sensing data to determine the relationships between the different factors and to analyse the reasons for the LUC and LDD as well as for modelling LU effects on LDD. The study revealed that: The changes in land use patterns (RA, FWL and FML) took place in 1973 – 86 – 2009, and affecting thoroughly different patterns of the vegetation cover. Likewise the LUC affected soil degradation which led to the movement of sand dunes in 1973 – 2009. The agricultural activity is the dominant and has more effect on LDD particularly on the vegetation cover degradation. The population growth and the socioeconomic status of local people are the main indirect human inducing factors responsible for LUC and/or LDD. SARVI is slightly more efficient than NDVI, SAVI, ND4-25 and ND42-57, for detecting the vegetation status in semi-arid area, therefore the study selected it for the assessment. GSI proved highly efficient in determining the different types of soil degradation, and in producing the map of top soil grain size, which assisted in the assessment of land degradation and desertification. OBIA-fuzzy logic classification performed better than the PBIA- hybrid classification for assessing LU patterns impact on LDD. The study recommends to: replication of this study by using different imagery with high resolutions and sophisticated software, such as eCognition and Feature Analyst (FA) for increasing the validity and accuracy of the assessment and modelling of LU patterns and LDD status in dry land is important in the Sudan.
Im 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.

Research Doctorate - Doctor of Philosophy (PhD)
The 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.

Research Doctorate - Doctor of Philosophy (PhD)
The 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.

Malleefowl are iconic Australian birds that build large mounds to incubate their eggs using external sources of heat. Malleefowl numbers have drastically decreased since European settlement and they are now a nationally threatened species. Their decline is caused by habitat loss and fragmentation; predation by introduced species; inappropriate fire regimes and competition and habitat degradation through overabundant native and introduced herbivores. Climate change is expected to exacerbate these pressures by leading to more frequent and longer periods of high temperatures, reduced precipitation and increased frequency and intensity of wildfires. This thesis aimed to investigate how historic and recent habitat fragmentation and climatic variables influenced Malleefowl on the Eyre Peninsula and how climate change may exacerbate future impacts. The objectives were to assess population trends, investigate landscape genetics, study movement patterns and the influence of habitat variables. These objectives were addressed through a multidisciplinary approach to study discrete Malleefowl populations at study sites located on the Eyre Peninsula in South Australia. To assess population trends and the influence of environmental factors, 24 years of mound-based breeding activity data were modelled. Results showed a widespread and significant decline in Malleefowl breeding activity during the study period, driven by changes in vegetation cover and reduction in soil moisture. High throughput DNA sequencing was used to investigate past dispersal patterns and the effects of recent anthropogenic land cover changes. The results indicate that Malleefowl population structure on the Eyre Peninsula was not homogenous and that habitat fragmentation with subsequent isolation has caused the differentiation of at least two distinct populations. Further, there was preliminary genetic evidence of female dispersal. Solar-powered GPS trackers were used to determine individual movement patterns and the effects of habitat fragmentation and environmental factors. Malleefowl movement was tightly associated with breeding status, with breeding birds staying close to the mound and non-breeding birds disassociating from the mound and moving long distances. Movement was also influenced by patch size and fragmentation, with non-breeding birds in large patches moving further than birds in smaller patches, but Malleefowl were able to persist in small patches and breed successfully for many years. Malleefowl moved less with increasing temperatures. Malleefowl did not use cropping land and they avoided crossing open paddocks. Malleefowl also had high mortality rates with over 66% of tracked individuals dying within a year of trapping, mostly from cat and fox predation. Vegetation surveys were combined with GPS tracking data to investigate whether Malleefowl movement was influenced by vegetation composition or cover. Results indicate that Malleefowl seek out micropatches of tall mallee stands within a mature Eucalyptus matrix – likely as refuges from heat and predators – and that movement is less driven by a preference for plant species, reflecting the fact that Malleefowl have a highly variable and opportunistic diet. In summary, this thesis shows how anthropogenic habitat alteration and changing environmental conditions have reduced breeding activity, restricted movement, dispersal and gene flow of Malleefowl populations on the Eyre Peninsula, with noticeable long-term genetic effects. Further, we can expect climate change to exacerbate all existing pressures and possibly drive Malleefowl closer to extinction. This research provides valuable new information about Malleefowl movement ecology which supports increased efforts to protect even small patches of native vegetation in agricultural matrices and the creation of habitat corridors between patches, as well as the improvements of matrix habitat, to facilitate between-patch movement. This, combined with continued and improved predator-control efforts, may enhance the conditions for future survival of Malleefowl populations, and support biodiversity in general, which is vital when faced with increasing climate change pressures.
Thesis (Ph.D.) -- University of Adelaide, School of Biological Sciences, 2022

Vertisols cover a hydrologically very significant area of semi-arid regions, and thus understanding of water flow and solute accumulation is very relevant to agricultural activity and water resources management. Previous works suggest a conceptual model of desiccation-crack-induced salinization where salinization of sediment in deep section of the vadose zone (up to 4 m) is induced by subsurface evaporation due to convective air flow in desiccation cracks. This thesis presents a conceptual model of water flow and solute transport in vertisols, and its numerical implementation. The model uses a single-porosity material but unconventionally prescribes a boundary condition representing a deep crack in soil and uses the unsaturated hydraulic conductivity as one of the fitting parameters. The numerical model is bound to one location close to a dairy farm waste pond, but the application of the suggested conceptual model could be possibly extended to all semi-arid regions with vertisols. Simulations were conducted using several modelling approaches with an ultimate goal of fitting the simulation results to the controlling variables measured in the field: water content, and chloride salinity of pore water. The development of the model was engineered in numerous steps; all computed as forward solutions by...