National-scale landslide susceptibility map of Romania in a European methodological framework

Abstract

Landslide susceptibility maps are useful tools for risk analysis and assessment with practical implications because they provide relevant information for territorial planning, land use sustainable management or even forecast and early warning systems. Achievement of accurate assessments of landslide susceptibility for large regions (i.e. including national territories) is still a challenge, mainly because of the lack of proper landslide inventory and monitoring data. Romania represents one of the most landslide-affected countries in Europe. The current study presents an approach for drawing the landslide susceptibility map at a national scale for the Romanian territory, in agreement with the European methodological framework promoted for small-scale evaluations of landslide susceptibility. The methodological approach was adapted to the specific mophostructural, climatic and landuse conditions of the country, as well as to the quantity and quality of the available data, in order to achieve a susceptibility zonation for slides and flows for the national territory. It follows a mixed statistical-heuristic approach based on a Spatial Multi-Criteria Evaluation (SMCE) procedure integrating both landslide information and expert knowledge. The national landslide susceptibility map outlines large areas ranked as having high and very high susceptibility throughout the Subcarpathian chain, the Moldavian and Transylvanian Plateaux and the Getic Piedmont. The prediction performance was examined quantitatively and qualitatively, by making use of regional geomorphical knowledge. The evaluations suggest that, despite uncertainties inherent at this analysis scale, spatially-differentiated models are able to better capture landslide conditioning frameworks and reproduce inter- and, especially, intraregional variability of landslide distribution as compared to a previous version of the national susceptibility map. The study proves that combining statistical and heuristic approaches, calibrated and later on validated for distinct homogeneous morpho-litho-structural units allows to increase the prediction capacity of the national-scale model. The results are useful to public authorities at national, regional, county and municipality levels, providing knowledge for the enhancement of disaster prevention and response plans.