Soil moisture mapping in a semiarid region, based on ASAR/Wide Swath satellite data

Mehrez Zribi (1) , Fatma Kotti (2) , Rim Amri (1, 2) , Wolfgang Wagner (3) , Marouen Shabou (1, 2) , Zohra Lili-Chabaane (2) , Nicolas Baghdadi (4)

1 CESBIO - Centre d'études spatiales de la biosphère
2 INAT-LRSTE - INAT Laboratoire Recherche-Développement Sciences et Technologie de l'Eau
3 Institute of Photogrammetry and Remote Sensing
4 UMR G-EAU - Gestion de l'Eau, Acteurs, Usages

In this paper, an operational algorithm is proposed for the mapping of surface moisture over the northern and central parts of Tunisia, in North Africa. A change detection approach is applied, using 160 multiincidence Envisat ASAR Wide Swath images acquired in the horizontal polarization over a 7 year period. Parameterization of this algorithm is considered for three classes of vegetation cover density (NDVI<0.25, 0.250.5), retrieved from SPOT-VGT decadal images. A relative soil moisture index, ranging between 0 (for the driest surfaces) and 1 (for saturated soils), is proposed for each date, with a resolution of 1 km. The retrieved soil moistures are validated by means of ground measurements based on continuous thetaprobe measurements, as well as low-resolution (25 km) ERS and ASCAT soil moisture products from the Vienna University of Technology (TU Wien). A qualitative relationship between spatiotemporal variations of moisture and precipitation is also discussed.

Mots clés: soil moisture; radar; ASAR/ENVISAT; SENTINEL1

Domaines: Interfaces continentales, environnement; Milieux et Changements globaux

Mehrez Zribi, Fatma Kotti, Rim Amri, Wolfgang Wagner, Marouen Shabou, et al.. Soil moisture mapping in a semiarid region, based on ASAR/Wide Swath satellite data. Water Resources Research, 2014, 50 (2), pp.1-13. ⟨10.1002/2012WR013405⟩. ⟨hal-00943877⟩