Estimating surface soil moisture from TerraSAR-X data over two small catchments in Sahelian part of western Niger

L'objectif de cette étude est de valider une approche basée sur la détection de changement dans des images radar TerraSAR-X multi-temporelles pour la cartographie de l'humidité du sol dans des zones sahéliennes. La méthode consiste à utiliser deux images radar, une acquise en saison sèche et une acquise en saison de pluie. La précision sur l'estimation de l'humidité est de l'ordre de 2.3% (RMSE). / The objective of this study is to validate an approach based on the change detection in multitemporal TerraSAR images (X-band) for mapping soil moisture in the Sahelian area. In situ measurements were carried out simultaneously with TerraSAR-X acquisitions on two study sites in Niger. The results show the need for comparing the difference between the rainy season image and a reference image acquired in the dry season. The use of two images enables a reduction of the roughness effects. The soils of plateaus covered with erosion crusts are dry throughout the year while the fallows show more significant moisture during the rainy season. The accuracy on the estimate of soil moisture is about 2.3% (RMSE) in comparison with in situ moisture contents