Variation characteristics of hydrological response to water conservancy construction in the Qinhe River Basin of the Loess Plateau, China

Abstract Investigating the response characteristics of various hydrological factors to water conservancy projects area in basin and evaluating their impact on the ecological environment are crucial for ecological protection and restoration on the Loess Plateau, China, with a complex environment. In this study, we employed a geomorphology‐based hydrological model to simulate the hydrological elements of the Qinhe River Basin on the Loess Plateau. We explored the response characteristics of the water cycle and hydrological processes to the construction of reservoirs in the basin. Additionally, we also examined multiyear changes in peak flood volume and sediment discharge during flood seasons influenced by reservoirs. The sub‐basins hosting reservoirs initialled an increase in evaporation, followed by a decrease. During the change periods, both runoff and soil water decreased, but remained higher than the mean values for the basin during the same period. The Normalized Difference Vegetation Index of sub‐basins associated with five reservoirs was obviously higher than the mean value for the basin during the same period. The peak flood volume and sediment discharge in the basin were characterized by decreasing trends, with the latter showing weak sustainability. The value of each index for a sub‐basin associated with a reservoir was higher than the average value for the basin. The construction and operation of reservoirs had a positive impact on the ecology of the basin. Water and soil conservation measures, including sediment regulation and storage using reservoirs, effectively decreased water hazard and soil erosion in the basin. This study provides a scientific basis for the construction of water conservancy projects and ecological governance in the basin.