Quantitative analysis of runoff alteration based on the Budyko model with time-varying underlying surface parameters for the Wuding River Basin, Loess Plateau

Abstract

The evolution of basin runoff is related to water resource development and the safety of the ecological environment. This study took the Wuding River Basin (WRB) as the study area, using trend analysis, significance tests, and the elasticity coefficient method to identify the impact factors of basin runoff change. Based on four Budyko equations and stepwise multiple linear regression analysis, a fitting equation of time-varying underlying surface parameters that considers various factors was constructed, and the contribution rates of climatic and vegetation changes to runoff change were quantified. The WRB Runoff decreased significantly (p ≤ 0.05) at a rate of −0.175 mm∙a−1 during 1982–2019, and precipitation and potential evapotranspiration showed significant increasing trends. Sensitivity of runoff changes to time-varying underlying surface parameters, precipitation, and potential evapotranspiration decreased sequentially. Simulation accuracies of the Budyko equations for runoff changes were significantly improved with time-varying underlying surface parameters. The change of vegetation factors was the dominant factor leading to runoff reduction, and the impact of climatic factors on the runoff change was characterized by “promotion first, inhibition later.” The results provide a reference for water resource development and utilization and the hydrological–ecological response in the Loess Plateau region under a changing environment.