Potential recognition of flash flood disasters in China’s southwestern mountainous areas considering source supply conditions

This study established a method for the potential recognition of flash flood disasters that is adaptable to different spatial scales considering source supply conditions. Based on digital maps for early potential recognition of flash flood risk, the potential volume of landslide sources in typical high-risk watersheds was estimated through the Transient Rainfall Infiltration and Grid-Based Regional Slope-Stability Model (TRIGRS) with slope as the basic unit. The results indicate that: (1) The coupling disaster caused by flash floods and sediment in Aba Prefecture exhibits a certain degree of spatial clustering, with some impact factors demonstrating similar sensitivity patterns towards disaster occurrence. (2) High risks of flash flood disasters are identified in parts of eastern, central-southern, and a small portion of the northwestern watersheds in Aba Prefecture. (3) The Certainty Factor-Adaptive Boosting (CF-AdaBoost) coupling algorithm identifies a coverage of 40.7% for high-susceptibility areas and a coverage of 12.4% for very low-susceptibility areas. (4) Post-processing the results of the slope stability model through the division of slope units estimates that the area of high-risk slopes in the Shouxi River basin during the intense rainfall event on August 20th is 4.99 × 107 m2. The key source supply areas are primarily concentrated in the upper and middle reaches of the basin, with an estimated sediment transport capacity of 1.219 × 107 m³ for each flood event.