Mapping of debris flows by the morphometric analysis of DTM: a case study of the Vrátna dolina Valley, Slovakia

The main objective of this contribution is to detect the morphogenetic processes by the numerical method of the differential geometry technique and compare the results with field surveying. The area of interest, the Vrtna dolina Valley, is located in the Mal Fatra Mountains in the northern part of Slovakia. Extensive mass movement deformations occurred in the surveyed area in 2014 induced by extreme precipitation events caused considerable damage. The Proxima software technology has been used to identify terrain elements using a precise digital terrain model (DTM) for the localisation of the debris flows head scarps. Precise DTM was derived from the airborne laser scanning (ALS) data. The morphometric analysis of landslide area was carried out on four selected locations. Verification of numerical mapping was performed by comparing results to the field survey data through visual comparison and area computation. Supplementary data was used in the form of orthophoto mosaics. The used spatial analysis applied on ALS data shows a high coincidence with the detection of the head scarps by field surveying, particularly in the hard to access and afforested areas. The main advantage of this approach lies in the reduction of field surveying and in the possible detection of the terrain changes not found during field surveying.