Estimation of the Areas with Accelerated Surface Runoff in the Upper Prahova Watershed (Romanian Carpathians) Liliana Zaharia1, Gabriel Minea1, Gabriela Ioana-Toroimac1, Ruth Barbu2, Ioan Sârbu1 1University of Bucharest – Faculty of Geography, Department of Meteorology and Hydrology, Bucharest, Romania 2University of Bucharest, Faculty of Geography, “Simion Mehedinţi – Nature and Sustainable Development” Doctoral School, Bucharest, Romania E-mail:
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[email protected] Abstract This paper aims to identify the areas prone to rapid surface runoff and, consequently, with high potential for flood occurrence. In order to reach this goal we relied on the Flash Flood Potential Index (FFPI), which integrates those physical parameters of the watershed that control the surface flow: rock permeability, soil texture, slope gradient, curvature profile and land use. The integration of these parameters was accomplished in a GIS environment, through multiple operations that included digitization, interpolation, cropping, conversion, classification, reclassification and cartographic algebra. The size of the grid cell was set to 20 (hence, the area of a pixel/cell was 400 m2). Depending on the favorability/restrictiveness of each flow control factor, five classes, numbered from 1 to 5, were established. By adding the specific values of each class with the investigated parameters, we obtained a new grid, called FFPI. This was further reclassified into four classes: very low, low, medium and high. The study area overlaps the Upper Prahova watershed, a region with significant socio-economic importance (especially for the road and railroad transportation, as well as for tourist activities), where floods and other associated phenomena (inundations, landslides) are frequent and may lead to serious damage.