Application of spatio-temporal variable source mixed runoff model to flood simulation of small watersheds:A Case study of four small watersheds in Sichuan and Gansu Province
In recent years, the casualties and property losses caused by flash flood disasters have been on the rise. Hydrological models based on GIS and remote sensing data can provide a new perspective for flash flood forecasting. Here, DEM and remote sensing data were adopted to extract basic attributes of small watersheds and to divide them into geomorphological and hydrological response units, then the discharge was calculated using vertical mixed runoff, and the infiltration was calculated using unsaturated soil in vadose zone, based on which the vertical spatio-temporal variable source mixed runoff model was established. Then the spatio-temporal variable source mixed runoff model (SVSM) was used to simulate multiple flood processes in four river basins of Gansu and Sichuan Province. The parameter calibration and runoff analysis were carried out using the shuffled complex evolution (SCE) algorithm. The results showed that the simulation results are consistent with the measured data, and the Nash efficiency coefficients are all over 0.8. Because small watersheds in Gansu and Sichuan Provinces are affected by the underlying surface information, their dominant runoff components are different. The proposed model can provide more accurate forecasting results for flash floods in hilly areas.