Coupling the Xinanjiang model with geomorphologic instantaneous unit hydrograph for flood forecasting in northeast China

The Xinanjiang (XAJ) model has been successfully applied in humid and semi-humid regions. Considering the geomorphologic factors to accurately estimate floods, this study adopted the geomorphologic instantaneous unit hydrograph (GIUH) method to calculate the surface runoff instead of the experience unit hydrograph (EUH) in the original model. The geomorphologic factors of the case study basin were obtained by using a digital elevation model (DEM) and the Terrain analysis using Digital Elevation Models (TauDEM). Furthermore, the dynamic Muskingum model was used for the channel flood routing. This study focused on the simulation of heavy precipitation and floods over the Chong River, which is a tributary river to the Songhua River on the right bank in northeast China. The detailed steps of the method were shown, up to the estimated value of flood runoff discharges and flood peaks and their comparison with observed values. The average deterministic coefficients (DCs) of model calibration and validation were 0.89 and 0.83, respectively. The results show that the model precision is high and the model is feasible for flood forecasting. Lastly, some methodological perspectives to enhance the method are presented.