Affiliation: | (1) BC Ministry of Forests, Bag 6000, Smithers, BC, V0J 2N0, Canada;(2) UBC Faculty of Forestry, 2424 main Mall, Vancouver, BC, V6T 1Z4, Canada;(3) Geohazards Division, Disaster Prevention Research Institute, Kyoto University, Gokasho, Uji, 611-0011 Kyoto, Japan;(4) BC Ministry of Forests, 712 Yates St., Victoria, BC, V8W 3E7, Canada |
Abstract: | Debris flows, debris floods and floods in mountainous areas are responsible for loss of life and damage to infrastructure, making it important to recognize these hazards in the early stage of planning land developments. Detailed terrain information is seldom available and basic watershed morphometrics must be used for hazard identification. An existing model uses watershed area and relief (the Melton ratio) to differentiate watersheds prone to flooding from those subject to debris flows and debris floods. However, the hazards related to debris flows and debris floods are not the same, requiring further differentiation. Here, we demonstrate that a model using watershed length combined with the Melton ratio can be used to differentiate debris-flow and debris-flood prone watersheds. This model was tested on 65 alluvial and colluvial fans in west central British Columbia, Canada, that were examined in the field. The model correctly identified 92% of the debris-flow, 83% of the debris-flood, and 88% of the flood watersheds. With adaptation for different regional conditions, the use of basic watershed morphometrics could assist land managers, scientists, and engineers with the identification of hydrogeomorphic hazards on fans elsewhere. |