Conditions of landslide development during the last decade in the Rożnów Dam-Lake region (Southern Poland) based on Airborne Laser Scanning (ALS) data analysis

Abstract

In order to identify the causes of landslide development in the area of Rożnów Lake (Outer Carpathians – southern Poland) in the last decade, Differential Digital Terrain Models (DDM) were used. These were made on the basis of Airborne Laser Scanning (ALS) data from four flights. The first ALS data are from 2010, before the event in Poland known as the “landslide catastrophe”. Comparing digital terrain models from different years tracking of changes in landslide activity relative to the intensity of precipitation. The article presents a method of investigating landslides with the use of DDM. This analysis allowed calculation of the displacement lithological index and of landslide susceptibility, based only on landslides that have become active in the last decade. The areas with the highest susceptibility to landslides are regions of Hieroglyphic Beds occurrence and of tectonic overthrusts. An important role in the development of landslides in the area of Rożnów Lake is also played by the thick-bedded Ciężkowice sandstones (usually associated with low susceptibility to landslides). After the “landslide catastrophe”, it is precisely in these formations that the greatest displacements and more frequent widening of the landslide boundaries were recorded, though they are generally stable during smaller rainfall.