资源环境科技发展态势分析平台

The Budyko framework, widely regarded as a simple and convenient tool to synthesize catchment water balance, is often employed with the atmospheric evaporative potential (E_p) that responds to water availability over a land surface. In this study, we demonstrated how the responsiveness of E_p to soil moisture deficiency affects outcomes from a conventional Budyko equation. We combined a two-parameter Budyko equation with the state-of-the-art complimentary relationship (CR) of evaporation (E), and analytically showed that the two-parameter Budyko equation corrects E_p to the wet-environment E (E_w) of the CR. Using the Budyko equation combined with the CR, we assessed runoff sensitivity to climatic and land surface changes. Results showed that the CR could become a constraint for calibrating the implicit parameter of the Budyko equation. When compared to the Turc-Mezentsev equation with E_p, the shape parameters of the two-parameter Budyko equation increased to regenerate an ensemble of global E datasets. Correcting E_p to E_w via the Budyko equation with CR reduced runoff elasticities to land property changes, suggesting that climatic changes are more important to changes in runoff than a prior sensitivity assessment would suggest. This study also suggests that the two-parameter Budyko equation isolates the effect of the E_p adjustment from the shape parameter, allowing it to more properly account for surface energy availability.