Impacts of Climate and Land Use/Cover Change on Water Yield Services in the Upper Yellow River Basin in Maqu County

The upper Yellow River Basin is an important ecological security barrier and a water conservation area in northwest China. The sustainability of its water yield services has generated much concern and debate. Spatial and temporal patterns of water yield factors are considered to be important scientific data. Therefore, the climate and land data of the upper Yellow River Basin in Maqu County are studied. Water yield for the period 1990-2020 was estimated using the water yield module in the InVEST model. Impacts and contribution weights of climate and land use/cover change on regional water yield were also quantified under 12 scenarios. The results indicate that (1) the average water yield in Maqu County has fluctuated and increased in the past 30 years. The increase in rainfall was more pronounced than the increase in potential evapotranspiration. Grassland areas continue to increase and unutilized land areas continue to decrease. (2) The average water yield for different types of land use during this period also varied. It showed grassland > unutilized land > forest > construction land > waterbody > cropland. (3) Climate change has a greater impact on water yield in Maqu County and further increases its contribution to regional water yield. The impact of land use/cover change was smaller and the contribution was smaller.