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Wageningen University (2000)

Estimation of areal soil water content through microwave remote sensing

Oevelen, P.J. van

Titre : Estimation of areal soil water content through microwave remote sensing

Auteur : Oevelen, P.J. van

Université de soutenance : Wageningen University

Grade : Doctor 2000

Résumé partiel
In this thesis the use of microwave remote sensing to estimate soil water content is investigated. A general framework is described which is applicable to both passive and active microwave remote sensing of soil water content. The various steps necessary to estimate areal soil water content are discussed through literature review, laboratory experimental results and results of extensive field experimental work. Even with the large amount of field data being available, no experiment provided all the necessary data to illustrate the framework completely for both passive and active techniques.

The framework developed is intended to be independent of the models used. In this way insight is gained in the dominating factors and problems associated with the use of remote sensing and not with specific models. Throughout the thesis both passive and active techniques are used and compared.

The passive techniques, mainly L-band and C-band, show better results that are more easily obtained at the cost of a relatively low spatial resolution. The standard error in the remotely sensed soil moisture estimates (< 5%) even in the presence of low to moderate vegetation cover is often lower than that of the ground truth measurements. The launch of a space-borne L-band radiometer will make this technique useful for mesoscale and global scale hydrological and meteorological modeling.

The active techniques are severely tampered by vegetation and surface roughness effects making soil water content estimation more cumbersome. Despite these drawbacks this technique is complimentary to the passive technique because of the higher attainable spatial resolutions and the possible use of longer wave lengths (P-band). The latter enables estimation of soil water content under vegetation cover and over larger depths, about 30 cm for P-band, compared to for example about 5-10 cm depth for L-band. The standard error of soil moisture estimates in absence of vegetation is in general around 5%.

Mots clés : soil water / estimation / measurement / soil texture / surface roughness / remote sensing


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Page publiée le 21 janvier 2015, mise à jour le 17 décembre 2021