资源环境科技发展态势分析平台

Climate change has been concerned as a trigger of hydrologic changes around the world. Budyko framework was widely used in hydrologic sensitivity analyses on the steady-state water balance. The unsteady-state responses, for example the inter-annual hydrologic sensitivity, were not well investigated, especially for catchments influenced by croplands as that exist in Illinois in the United States. We propose a new hydrologic sensitivity framework for the unsteady-state condition, together with a new hydrological model, to investigate the impact of croplands on the hydrologic sensitivity. In addition to the Budyko-type relationship between the annual evapotranspiration ratio (E/P) and the aridity index (E_p/P), this framework incorporates the empirical relationship between the annual storage change ratio (ΔS/P) and E_p/P into sensitivity coefficients. The required data of annual E/P and ΔS/P could be obtained from observation and hydrological models. In particular, the bcd-αK model is newly developed from the existing bcd model in considering croplands in Illinois, which includes only five parameters while capturing major hydrological processes for catchments with croplands. Results show that the annual E/P, ΔS/P and Q/P in twelve studied catchments have significant linear relationships with E_p/P. The annual runoff is much more sensitive to the change in precipitation than to the change in potential evapotranspiration. The traditional steady-state analysis overestimates the sensitivity of the evapotranspiration to the change in the precipitation for the unsteady-state condition and underestimates the variability of sensitivity coefficients among catchments.