Arid land surface characterization with repeat-pass SAR interferometry

Repeat pass ERS SAR interferometry was used to map different surface types of the Death Valley Salt Pan. At this arid site, the surface roughness varies between extremely smooth (salt lakes, clay pan) and very rough (alluvial fans, eroded salt formations). The moisture varies from very dry (alluvial fans) to wet (wet clay, salt crust with water ponds) with seasonal changes In certain areas. While the surface geometry is stable for certain surface types (alluvial fans, thick salt crusts), it changes for others as a result of the changing water level and erosion by wind and rain. The changing surface roughness, moisture, and vegetation conditions cause large variations of the backscattering and coherence. This information is used to distinguish different surface types. Furthermore, interferometry was used to map the topographic height. In a second part of the study, the potential of the degree of coherence to retrieve information on the vegetation density and the surface erosion was evaluated.