Assessment of flash floods occurrence and the spatial distribution by inventory and morphometry of the Bermejo Basin, San Juan, Argentina

Abstract

This study aims to identify areas prone to flash floods and their distribution in the Bermejo Basin (San Juan, Argentina). This assessment is carried out through regional morphometric analysis, a flash flood inventory, thematic indexes from a Digital Elevation Model (DEM), and Kernel density calculations. The assessment includes basic and derived parameters analysis within the river sub-basins. The Bermejo Basin, covers 20735.74 km2 , with a perimeter of 1316.57 km and a total river length of 577.47 km. It is classified as a 7th order basin (Strahler, 1952a) and consists of two 6th order sub-basins. A total of 3156 flash flood deposits have been inventoried. The basin has a torrential rainfall character and the area’s most prone to flash flood generation are concentrated inmountainous regions, sierras and escarpments. Once initiated, these flows traverse the landscape and exhibit high erosive potential due to the steep slopes. Flash flood deposits are predominantly found in slightly rugged terrain with slopes up to 10◦, particularly in mid-slope, foothill areas, and low-lying floodplains. These areas are highly susceptible to flash floods, which significantly impact on routes, infrastructure, and human activities.Kernel density indicates a high concentration of flash floods in the mountainous units of Sierras Pampeanas and Precordillera.