Sensitivity of Regional Hydrology to Climate Changes, with Application to the Illinois River Basin

This paper investigates the sensitivity of regional hydrology to climate change using a physically based model. The model partitions precipitation into surface runoff, groundwater runoff, and evapotranspiration by describing these fluxes first at the local instantaneous scale and then integrating over spatial and temporal distributions of soil saturation, precipitation, and wet environment evapotranspiration to calculate basin-wide climatic mean fluxes and soil saturation. The sensitivities of the mean fluxes are calculated by changing the mean precipitation and wet environment evapotranspiration. The model is applied to the Illinois River basin, and the impact of the basin’s characteristics on the sensitivities is studied. For a relatively broad range of conditions the runoff processes tend to amplify climate change signals in precipitation and wet environment evapotranspiration, while evapotranspiration processes tend to dampen the same signals. These results indicate that it may be easier to detect climate changes in runoff measurements than in precipitation measurements.