Landslide susceptibility zonation in the Tartagal River basin, Sierras Subandinas, Salta, Argentina

On February 2009 intense rainfall triggered landslides in the Tartagal River basin that evolved into a debris flow that caused severe flooding in the town of Tartagal, Salta, Argentina. Based on these events, this paper presents a first attempt to map the landslides susceptibility in the Tartagal River basin. First, we elaborated an inventory map by using a 10 m pixel SPOT image acquired just after the disaster. Second, we evaluated a set of conditioning factors, which included lithology, slope and curvature; we derived the topographical variables from a 12.5 m pixel digital elevation model (DEM) based on a stereo-pair of satellite images ALOS-PRISM. Finally, we used these conditioning factors and the 2009 landslides inventory map as input for a heuristic model to elaborate the susceptibility map. The results indicated that landslides affected an area of 8 km2 and that at least 2.2x106 m3 of material were removed. The susceptibility map identified zones of low, moderate, high and very high susceptibility that occupied 18, 22, 25 and 17 km2, respectively. Accuracy assessment using data covering landslides occurred in 2006 showed that 95% of them fell within the high and very high susceptibility areas. The results presented herein provide vital baseline information for future studies and may contribute for the development of landslide hazard mitigation strategies.