A complex sediment yield and transportation model for mountain area

In Taiwan, the catastrophic typhoon is an important factor to trigger serious landslides in mountains. For example, Typhoon Morakot in 2009 caused 39,492 hectares for landslide areas. The sediments yield from landslides triggered the mass movement in the mountains and caused serious hazards. In order to make the manage plan for watersheds, an applicable numerical model is needed to estimate the mass movement. In this study, the purpose of this research is to establish a model for sediment yield and transportation in a watershed. The process of sediment yield and transportation in a watershed could be simulated during rainfall. The processes of sediment yield and transportation, which including several major mechanisms, runoff, soil erosion, groundwater, shallow landslide, channel flow, bed load, suspended load, river bed and sediment size variation are established in this model. The scheme of the model is setup as quasi-two dimension model and based on mass conservation. This scheme can shorten lots time in simulation, and shows more detail terrain characteristic in special scale, resulting in sediment yield and transportation can be accurately assessed. The numerical analysis of this model are also preceded in this research. Finally, the Blackstone watershed in Central Taiwan is selected to simulate the process of sediment yield and transportation during 2005 to 2011 by this model. The simulation shows this model could provide good result at sediment movement in watershed. So the model is effective in watershed management.