Applicability of the HBV model to a human-influenced catchment in northern China

The Hydrologiska Byrans VattenbalansavdeIning (HBV) model is a catchment hydrological model that has been widely applied to hundreds of catchments worldwide. Taking the Nanjuma River Basin which is located in a semi-arid climate zone and has been highly regulated by human activities, as a case, the applicability of the HBV model to the basin was investigated. Results show that (1) due to environmental change, recorded stream flow of the Nanjuma River presented a significant decreasing trend, and the relationship between runoff and precipitation was changed as well, with the correlation coefficient decreasing from 0.58 in the natural period of 1961-1979 to 0.01 in a highly regulated period of 2000-2018. (2) The HBV model performs well on daily and monthly discharge simulation for the natural period with the Nash-Sutcliffe efficiency (NSE) coefficients in calibration and validation periods of 0.63 and 0.81 for daily discharge simulation. (3) The HBV model's applicability would like to decrease when the Nanjuma River Basin was moderately and intensively regulated by human activities. The daily-scale NSEs in moderate-disturbance and intensive-disturbance phases are 0.42 and-0.3, which means the HBV model almost lost its capacity in capturing hydrological features for a highly regulated catchment.