Large scale simulation of watershed mass transport – a case study of Tsengwen reservoir watershed

Abstract

We present the large scale simulation of watershed mass transport, including landslide, debris-flow and sediment transport. A case study of Tsengwen reservoir watershed under the extreme rainfall triggered by typhoon Morakot is simulated for verification. This approach starts with volume-area relationship formula with inventory method to predict temporal and regional landslide volume production and distribution. Then, debris flow model, Debris-2D, is used to simulate the mass transport of debris-flow from hillslope to fluvial channel. Finally a sediment transport model, NETSTARS, is used for hydraulic and sediment routing in river and reservoir. The integrated simulation for the whole watershed gives a very good agreement with the temporal variation of sediment concentration recorded at the very downstream location.