Runoff Simulation in the Heiyukou Sub - basin of Weihe River Basin and its Responses to Climate Change Based on HIMS

Weihe River, as the first largest branches of the the Yellow River, is intensely affected by human activities. We took the HeiYuKou Sub basin (HYK), located in the middle areas of Weihe River Basin, as the study area and constructed a lumped hydrological model to simulate daily runoff and its responses to climate change. Based on the hydrological data, we choose the span from 1991 to 1996 as calibration period, and the period from 1997 to 2000 as validation period. In addition, we established eight climate change scenarios to contribute to analyze the responses of runoff to climate change based on the validated hydrological model: Main results are as follows: (1) Nash - Suttcliffe Coefficient (NSC) and Correlation Coefficient (CC) are relatively high both in the calibration and validation period. In the calibration period, NSC and CC are 0. 64 and 0. 65 respectively, while in the validation span they are 0. 63 and 0. 66 respectively. (2) Water balance Error (WE) in the validation is 10%, which is unsatisfactory. The reason is the poor performance of HIMS in the simulation of peak floods, which need to be improved. (3) the daily runoff is sensitive to the changes of precipitation and potential evaporation, and the sensitivity value to precipitation is higher than to evaporation. the relationship between runoff change and precipitation change is positive, (4) while that between runoff change and potential evaporation change is inverse. Both of the two responses are nonlinear.