Morphometric analysis and risk assessment of flash floods in the Atlas chain of eastern Algeria and the Algerian–Tunisian borders

Flash floods, known for their sudden onset and severe damages, present a major threat due to intense rainfall occurring within a brief period. This study focuses on the Tebessa Basin as a patt of the Atlas chain of eastern Algeria, and employs a comprehensive approach to morphologically characterize hydrographic units, aiming to assess flash flood risks and propose preventive measures. We implemented a prioritization and classification methodology for the basin’s hydrographic units using a weighted sum analysis (WSA) and morphometric modeling, utilizing 15 morphometric criteria. The modeling and determination of sub-basins and the drainage network relied on digital elevation model (DEM) data. Our analysis identified sixteen sub-basins within the main Tebessa Basin. Each sub-basin was categorized according to its priority level (very high, high, moderate, low, and poor) based on composite factors determined through the WSA. The results revealed a very high flash flood risk covering 6.55% of the Tebessa Basin (sub-basin 5), a high risk encompassing 35.33% (sub-basins 2, 4, 8, 11, and 12), and a moderate risk extending to 55.68% (sub-basins 1, 3, 7, 9, 10, 14, 15, and 16). In addition, there was a low flood risk (1.85%—sub-basin 13) and a poor flood risk (0.58%). Our study pinpointed sub-basin 5 as a focal point for major flash flood risk, indicating the necessity for targeted mitigation actions. These findings provide valuable insights for formulating effective strategies to alleviate the consequences of this natural hazard, contributing to the advancement of flash flood risk management in the Tebessa Basin.