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Accueil du site → Doctorat → Pays-Bas → 2000 → Satellite passive microwave surface moisture monitoring A case–study on the impact of climatic variability and land use change on the regional hydrogeology of the West La Mancha region in semi–arid central Spain

Vrije Universiteit te Amsterdam (2000)

Satellite passive microwave surface moisture monitoring A case–study on the impact of climatic variability and land use change on the regional hydrogeology of the West La Mancha region in semi–arid central Spain

Gouweleeuw Bernardus Theodorus

Titre : Satellite passive microwave surface moisture monitoring A case–study on the impact of climatic variability and land use change on the regional hydrogeology of the West La Mancha region in semi–arid central Spain

Auteur : Gouweleeuw Bernardus Theodorus

Université de soutenance : Vrije Universiteit te Amsterdam

Grade : Doctor 2000

Introduction
Soil moisture is the temporary storage of precipitation within a layer of shallow depth at the land surface–atmosphere interface. In general, this layer is limited to the zone of aeration and approximately coincides with the root zone. For the purposes of the present study, surface moisture or topsoil moisture is defined as the water content of the very upper part or top of the soil profile, corresponding to a 5 cm soil depth or as otherwise indicated. Surface moisture is an important integrating parameter in the processes responsible for the exchange of water and energy at the soil–atmosphere interface. Accordingly, it plays a significant role in large–scale atmospheric circulation processes [e.g. Beljaars et al., 1993 ; Betts et al., 1994]. Changes in these processes through time are reflected in the surface moisture and, as such, it may be used as an indicator of climatic variability and/or land use change. Soil moisture is extremely difficult to measure in time and space, especially at large spatial scales. It changes constantly as a result of precipitation events, evaporation processes (which include extraction by vegetation) and redistribution within the soil. Soil moisture is highly variable on both small and large spatial scales, due to the variability of precipitation and the heterogeneity of the land surface (e.g. vegetation, soil physical properties, topography, etc.). While point sampling is for the most part reliable, areal averaging of these measurements, especially at spatial scales of 102 − 103 km2, will often introduce large errors

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