A RS/GIS study of rapid erosion in SE Spain using ERS SAR multi-temporal interferometric coherence imagery

Soil erosion is a widespread problem in semi-arid Mediterranean countries where irregular, intense rainfall can result in rapid erosion in areas of steep slope, soft lithology and sparse vegetation. This paper presents an integrated remote sensing/GIS approach to identify areas vulnerable to rapid erosion in Almería Province, Southeast Spain. ERS SAR multitemporal interferometric coherence imagery is used to extract information on the erosion process, which causes random changes in the micro-topography of the land surface. This results in reduced coherence of the radar signals between the initial and eroded states. A known case of rapid erosion within the study area has been investigated using coherence images with 70, 140 and 210 days temporal separation. A GIS is then used to derive criteria for a set of environmental conditions causing susceptibility to rapid erosion. Slope is extracted from SAR interferogram; vegetation and lithology from ETM+ imagery. The areas predicted to be most vulnerable to rapid erosion across the imagery are then identified. The methodology provided by our study will help local land management authorities to understand where this type of erosion may occur. The research is supported by the ESA ERS AO3-113 project.