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Justus-Liebig-Universität Gießen (2008)

Water fluxes on different spatial and temporal scales in a semi-arid steppe environment : experimental and modelling approaches

Schneider, Katrin

Titre : Water fluxes on different spatial and temporal scales in a semi-arid steppe environment : experimental and modelling approaches

Auteur : Schneider, Katrin

Université de soutenance : Justus-Liebig-Universität Gießen

Grade : Dr. rer. nat. 2008

Résumé
The presented study examines the impact of land use on hydrological processes in a steppe environment in northern China. Thus, a better understanding of the driving hydrological processes on different spatial and temporal scales will be obtained. The study took place in the Xilin river catchment in the Autonomous Region Inner Mongolia (PR China). Land use is dominated by grazing (mainly sheep), which resulted in degradation of soils and vegetation in some areas. The impact of grazing on water fluxes was analysed with experimental as well as with modelling approaches. Soil moisture measurements took place on five areas (approx. 1.5 ha each) with varying grazing intensity. The results show a) that the spatial distribution of soil moisture depends on the vegetation characteristics of the respective area and b) that despite there is no linear relationship between grazing intensity and soil moisture storage, grazing does have strong influence on productive and unproductive evaporation. Model studies using the hydrological model SWAT showed that evapotranspiration plays an important role in the study area during the vegetation period. Nevertheless, different methods used to calculate evapotranspiration do not have a major impact on the overall performance of the hydrological simulations. In order to extend the data basis for the hydrological simulation and to eventually increase the process understanding in the Xilin catchment, soil moisture data derived from satellite products (ERS-1/-2) were compared with ground based soil moisture measurements. The remote sensing data fail to reproduce ground based measurements due to the small scale spatial variability of convective precipitation, and hence, are only of limited utility in the study area.

Mots Clés : soil moisture, spatial variability, land use, semi-arid steppe, hydrological modelling

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Page publiée le 31 août 2010, mise à jour le 8 janvier 2019