Sensitivity and attribution analysis of vegetation changes on evapotranspiration with the Budyko framework in the Baiyangdian catchment, China

Abstract

Due to its role in intercepting and evaporating water, vegetation has a great influence on the catchment hydrological process, and an increased quantitative understanding of how vegetation changes affect the terrestrial water cycle is of considerable interest for a range of spatial scales. In this study, we determine the effects of vegetation changes on evapotranspiration within the Budyko framework by adapting an analytical expression between vegetation and the Budyko parameter at a steady state. We then analyzed the attributions for evapotranspiration change in the Baiyangdian catchment and quantified the effects of vegetation change. The evapotranspiration changes during 1998–2017 in the Baiyangdian catchment were mainly caused by climate change, which accounted for 58.56%, and the contribution of the Budyko parameter (n) change to evapotranspiration was 40.04%. Among the impact factors, the effect of vegetation change on evapotranspiration was not the largest, with vegetation changes in the Baiyangdian catchment resulting in a decrease in evapotranspiration of 22.9715 mm, but only accounting for 10.23%. And we also discuss the spatial pattern of the sensitivities of evapotranspiration to vegetation based on the 66 catchments in the Hai River basin, and the results indicate that an increase in the normalized difference vegetation index (NDVI) would cause a decrease in evapotranspiration in dry regions (W < 1) and cause an increase in evapotranspiration in wet regions (W > 1). Evapotranspiration was more sensitive to NDVI changes in regions of W closer to 1.