Examples of landslide dams and their stability in the Blanco River basin. Central Andes, San Juan Argentina

Abstract

The blocking of river valleys and the subsequent formation of a landslide dam are very common in tectonically-active mountainous areas with deep and narrow valleys, like the Blanco River basin region, in the Dry Andes of Argentina. The present study examines five landslide dams, in the Blanco River basin, their evolution and their stability using some morphometric-based stability indices. In historical times, only one of these five landslide dams, the one located on the Santa Cruz River, failed catastrophically. However, the larger landslide dam in the study area, the one called Laguna Blanca, persisted for a longer period of time. The rest of the landslide dam lakes reduced in size over time through stream incision and sediment infilling. For some of these landslide dams, the geomorphological stability indices forecasted stable conditions which are consistent with the observed long-term persistence of them.