Erosion and Landuse Change Detection Using ERS SAR Interferometric Coherence Imagery (ESA ERS AO3-113)

This paper reports the main findings of ESA ERS AO3-113 project for erosion detection in SE Spain using ERS SAR multi-temporal coherence images. Coherence images derived from fringe pairs with temporal separation from 70 to 526 days of Almeria region and from two one-day tandem pairs of Granada region were analysed in conjunction with interferograms, topographic maps, TM images and geological maps. Evidences of rapid erosion were found on the slopes of marls where the vegetation cover is nearly none. The comparison between two coherence images of tandem pairs taken across a rainfall event and in dry conditions revealed the dynamics of rainfall/erosion process in relation to slope, lithology and vegetation cover. Large areas of disturbed lands were defined by image features with high coherence in 70 but de-coherence in 140 days. These features closely correspond to the recent massive plantation of olive and almond trees on gentle slopes of phyllites and schists. The stripping off the nature vegetation and surface crust of the land makes the thin soil vulnerable to erosion.