Recognition of the Susceptibility of Hydrogeomorphic Processes in Mountainous Watersheds through Morphometric Indicators and Field Reconnaissance

The morphometric parameters associated with hydrogeomorphic disasters such as debris flows, debris floods and floods in western Taiwan and Sichuan, China are analyzed in this study by employing the 5-m resolution digital terrain map and field studies. The drainage areas for debris-flow prone basins are within a wide range of 0.01-100 km. The morphometric parameters such as Melton Ratio (MR) and watershed length (L) are applicable to the identification of the debris-flow prone ravines. Through field reconnaissance, MR=0.3 can be regarded as the morphometric threshold for debris-flow basins in different regions, and their fan slopes are greater than 3 degrees. The debris-flow fan slope also increases with increasing MR values.