Erosion is an important exogene process that can be found on almost all surfaces around the globe and Slovenian territory is no exception to the rule. The extent of the erosion is a result of various factors linked to the surface properties, such as land use type, vegetation type, and geomorphology and of the factors linked to the climate, such as the precipitation regime and the temperature oscilation. The paper focuses on the modelling of the mechanical erosion and the surface transport of particles due to surfiial waters. The aim of the research was to combine the RUSLE surface erosion method with a model of gully erosion. The combined approach successfuly models the erosion in the mountainous and karst areas. Due to its vivid geomorphology that results in various natural surface proceses the area of Bohinj municipality was chosen as an ideal case study for testing the joint methodology.