Application of a developed distributed hydrological model based on the mixed runoff generation model and 2D kinematic wave flow routing model for better flood forecasting

Due to the specific characteristics of semi-arid regions, this paper aims to establish a Grid-and-Mixed-runoff-generation-and-two-dimensional-Kinematic-wave-based distributed hydrological model (GMKHM-2D model) coupling a mixed runoff generation model and 2D overland flow routing model based on kinematic wave theory for flood simulation and forecasting with digital drainage networks. Taking into consideration the complex runoff generation in semi-arid regions, a mixed runoff generation model combining saturation-excess mechanism and infiltration-excess mechanism is developed for grid-based runoff generation and 2D implicit finite difference kinematic wave flow model is introduced for routing to solve depressions water storing for grid-based overland flow routing in the GMKHM-2D model. The GMKHM-2D model, the GMKHM-1D model with coupling the mixed runoff generation model and one-dimension kinematic wave flow model, the Shanbei model and the Xin'anjiang model were employed to the upper Kongjiapo basin in Qin River, a tributary of the Yellow River, with an area of 1454 km(2) for flood simulation. Results show that two grid-based distributed hydrological models and the Shanbei model perform better in flood simulation and can be used for flood forecasting in semi-arid basins. Comparing with GMKHM-1D, the flood peak simulation accuracy of the GMKHM-2D model is higher.