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

Claudia Paola Cardozo,Valérie Baumann,Guillermo Toyos

doi:10.5027/andgeov48n1-3242

Abstract

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.

Highlights

Argentina shows a complex scenario as regards natural hazards, given by its extension and by the diversity and heterogeneity of its environments (Fernandez Bussy et al, 2010)
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
We developed a DEM of 12.5 m spatial resolution by using digital photogrammetry with a stereo-pair of satellite images captured by the sensor ALOSPRISM on 27 April 2008

Summary

Introduction

Argentina shows a complex scenario as regards natural hazards, given by its extension and by the diversity and heterogeneity of its environments (Fernandez Bussy et al, 2010). On 9 February 2009, intense rains triggered landslides in the Tartagal River basin that coalesced and evolved into a debris flow that travelled along the Tartagal River (Fig. 1) and resulted in the destruction of the main bridge of the city of Tartagal and severe flooding. Two people killed, 1,000 evacuated and severe material damages were reported (Baumann et al, 2009, 2011; Brea et al, 2013). Events of this type occurred in the past but none of the magnitude of the February 2009 disaster (Adler, 2009).

Objectives

Results

Discussion

Conclusion