Loess Slope Instability Assessment Based on PS-InSAR Detected and Spatial Analysis in Lanzhou Region, China

Abstract

Lanzhou is a mountainous city in which serious disasters have occurred due to several slope hazards. We used PS-InSAR technique to detect surface deformation: an indicator of potential hazards. In the period extending from 2003 to 2010, 41 Envisat ASAR images were captured and analyzed using PS-InSAR. We identified 27186 PS points. The deformation velocity in this area is found to being 3.5 mm/year ~ -5.4 mm/year. The results were inserted into a GIS to derive spatial interpolations and map zones with different magnitudes of surface displacement. Then, we used the analytical hierarchic process (AHP) to statistically assess the susceptibility of loess slope hazards with lithology, slope, altitude, distance to road, Ndvi, land use and aspect. According to the result of the model, the study area could be classified into three categories: stable, less unstable and unstable. Causal mechanisms include human interactions in the landscape (construction, waste water discharge, etc.) and slope instability processes (landslide, subsidence, etc.).