Isolating of climate and land surface contribution to basin runoff variability: A case study from the Weihe River Basin, China

Affected by climate variability and human activities, the changes of basin environment have altered runoff, posing new challenges to water resources and land use management strategies, especially in areas with limited water resources. The purpose of this study is to quantify factors that drive the changes in runoff components. Annual runoff data from six hydrological stations in the Weihe River Basin, China and sixteen meteorological stations data from 1961 to 2015 were used. The Mann-Kendall test and Pettitt method were used to diagnose the runoff sequence and detect its abrupt-point. The period before the abrupt-point of annual runoff was taken as the base period (Period I), while the period after the abrupt-point was taken as the calculation period (Period II). The elasticity coefficient of runoff (Q) was deduced based on the Budyko hypothesis, including climate variabilities such as precipitation (P) and potential evapotranspiration (Ep), and the catchment characteristics representing land surface changes (n). The elasticity coefficient was the smallest for Ep ranging from -1.210 similar to -2.847, intermediate for n ranging from -1.602 similar to -2.964, and greatest for P ranging from 2.2103.847. Runoff exhibited a significant downward trend throughout the Weihe River Basin, where the land surface change is the main cause of runoff reduction, accounting for 75% at the largest Linjiacun hydrological station, with the smallest being 40.36% at the Zhuangtou hydrological station. Adaptive water resource management measures are necessary to cope with future environmental change and water resource scarcity.