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Accueil du site → Doctorat → Allemagne → 2004 → Untersuchungen zum Bodenwasserhaushalt und Modellierung der Bodenwasserflüsse entlang eines Höhen- und Ariditätsgradienten (SE Marokko)

Rheinischen-Friedrich-Wilhelms Universität Bonn (2004)

Untersuchungen zum Bodenwasserhaushalt und Modellierung der Bodenwasserflüsse entlang eines Höhen- und Ariditätsgradienten (SE Marokko)

Weber, Benedikt

Titre : Untersuchungen zum Bodenwasserhaushalt und Modellierung der Bodenwasserflüsse entlang eines Höhen- und Ariditätsgradienten (SE Marokko)

Analyse and modelling of soil water dynamics along a gradient of elevation and aridity (SE Morocco)

Auteur : Weber, Benedikt

Université de soutenance : Rheinischen-Friedrich-Wilhelms Universität Bonn

Grade : Dr. rer. nat. 2004

Résumé
The objective of this study is to measure and analyse the most important control factors of soil water regime in a semiarid environment. The study is integrated in the IMPETUS-Project and focusses knowledge of soil-hydrological components of the water cycle within Drâa river catchment in Morocco. Due to the fact that previous studies in the catchment are only focusing the irrigated fraction of the catchment, a validation data base for the rangeland does not exist. Hence, seven representative testsites along a gradient of aridity and altitude were defined and have been discretised in terrain types with respect to their soil hydrological attributes. During a three years campaign relevant hydrological and soil data have been conducted and analysed. As a result, terrain types with high infiltration capacity and low disposition for runoff concentration could be distinguished from surfaces which tend to produce overland flow. Terrain units covered with rock fragments, shallow soil depths and topographic convexities show the lowest infiltration rates. In contrast to these units with high infiltration capacity can be found where ephemeral channel networks, topographic depressions and vegetation occurs. The patchwork-like pattern of terrain unit varies distribution. The results of the measurements were used to validate a model for simulating soil water fluxes. The process-based model ARID was calibrated and validated for each of the seven testsites. Facing the climatic variability and the heterogeneity of soil hydrological properties the results approve that main processes of soil water balances are applicated by the model. The simulation of soil water content leads to good results. In Dependance to the spatial scale this approach can be used for representing soil water dynamics. Due to the missing validation data (at four of the seven testsites no runoff occurs) and the underestimation of slow runoff components only moderately goodness-of-fit was achieved. Furthermore, the actual model version does not sufficiently represent complexity of different aquifer systems in the High Atlas. Modelled soil water components are pointing out strong dependance to the gradient of aridity. In addition to this, dynamics of evaporation, transpiration and soil water content were mainly affected by local, soil hydrological properties such as texture, soil depths and rock fragment cover. This secondary influence can not be explained by the gradient between High Atlas and presaharian desert. The impact of these local properties on water cycle components can be demonstrated by the comparison with the testsite’s position within the transekt. Especially in the view of sparsely information density concerning hydrological data, the used methodology and the application of the model contributes to the understanding of water balance in arid environments.

Mots clés : Oued Dra ; Einzugsgebiet ; Bodenwasserhaushalt ; Bodenwasserstrom ; Simulation

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Page publiée le 25 mars 2008, mise à jour le 11 novembre 2021