Hydrological response to climate change and human activities in the Bahe River, China

Streamflow and its components, such as baseflow, are momentous links of the hydrological cycle, and their spatiotemporal variations are affected by both climate change and human activities (CCHU). However, dis-crepancies in the influence of CCHU on streamflow and hydrological components are not fully understood. In this study, meteorological factors (precipitation and potential evapotranspiration) and hydrological variables (streamflow and baseflow) were analyzed to quantify the responses of the streamflow and baseflow in the Bahe River to the CCHU during 1959-2016. The hydrometeorological variables in the Bahe River showed a downward trend, except for the baseflow at the Luolicun hydrological station (LLC), while the mutation point at the Maduwang hydrological station (MDW) was in 1989, and LLC was mutated in 1980 and 1989. Precipitation was closely related to streamflow in comparison with baseflow (r = 0.871 +/- 0.034), whereas potential evapo-transpiration was the opposite. The streamflow and baseflow at MDW had closer relationships with precipitation than at LLC (r = 0.828 +/- 0.077), while LLC was more affected by potential evapotranspiration (r =-0.698 +/- 0.004). Streamflow and baseflow upstream of the Bahe River were mainly affected by human activities (67-75 % and 74-78 %, respectively), and baseflow midstream due to climate change (90-147 %). The contributions of climate change and human activities to midstream streamflow were 37-75 % and 25-63 %, respectively. Our findings highlight the responses of streamflow and baseflow to environmental changes, which will enhance our understanding of the response mechanisms of the hydrological cycle in a changing environment.