Simulation of gravitational erosion in river basins on loess plateau

Gravitational erosion is one of the main forms of soil erosion. On the Loess Plateau in China. gravitational erosion effectively contributes to the total amount of soil erosion, the characteristics of hyper-concentrated sediment-laden flow and scale phenomena of sediment processes. However, gravitational erosion happens randomly with complex mechanism, and in-situ measurements are absent, thus simulation of gravitational erosion is still a weak point in soil erosion research. After solving a few application problems of gravitational erosion model in river basins, a theoretical model for gravitational erosion based on soil destabilization was integrated with rainfall-runoff-soil erosion model for hillslope and non-equilibrium sediment transport model for channel in the digital watershed model. Thus, the gravitational erosion model can appropriately simulate gravitational erosion processes in river basins according to the shape of gullies and its variation caused by channel flow wash, and the mechanical property of loess and its variation with moisture content caused by rainfall. The integrated model system was applied in Chabagou watershed and Wuding river basin. Results of distribution of gravitational erosion and its proportion in total soil erosion were proved reasonable.