Impact of surface and underground water uses on streamflow in the upper-middle of the Weihe River basin using a modified WetSpa model

Anthropogenic water use activities contribute substantially to natural hydrological processes. However, their effects on distributed hydrological simulations are currently poorly understood due to the lack of observed data on water use. To address this issue, we developed a model by using the Water and Energy Transfer between Soil, Plants, and Atmosphere (WetSpa) with water withdrawal and consumption modules, namely WetSpa-WW. Differently from previous studies roughly estimating water use, the observed withdrawal of surface water and groundwater, as well as industrial, domestic, and agricultural water consumption in sub-basins, were used ac-cording to the site-based measurements. This model was applied to the upper and middle reaches of the Weihe River Basin (UMWRB). Results show that: (1) The proposed WetSpa-WW improved simulation efficiency both of streamflow and actual evapotranspiration (AET), e.g., the relative error (RE) of AET decreased from 20.3 % to-6.43 %. (1=2) The RE of streamflow at the outlet of the basin increases from 10.5 % to 15.3 % without considering the spatial distribution of water use among sub-basins. (3) In the period of 2017-2020, the mean water withdrawal stood at 49.64 mm/a over the basin, resulting in a reduction of streamflow by 22.24 mm/a and an increase of actual evapotranspiration by 6.97 mm/a. This study demonstrates a great potential gain available to the distributed hydrological models integrating records of actual water use, rather than more widely used national statistics.