The aim of this study is to identify and map the zones of different vulnerability to flash floods based on the geospatial analysis of natural conditions in the Porečka River basin (Republic of Serbia). The analysis covers the catchment area of the Porečka River (493.82 km2 ). Geospatial analysis was conducted using GIS software (QGIS 3.18). The Flash Flood Potential Index (FFPI) was used to determine the terrain's predisposition to flash floods, where the input data for determining the value of the index were the values of the following coefficients: the terrain slope, the type of geological substrate, the way of land use, and the bareness of the terrain.