Improving the characteristics of streamflow modeled by regional climate models.

The introduction of complex land surface parameterization schemes into regional climate models (RCMs) has been focused on improving the modeling of land surface feedbacks to the atmosphere. As such the modeling of streamflow was considered a by-product of the water balance and until recently it received relatively little attention. Comparison of four RCMs (RegCM2, MM5/BATS, MM5/SHEELS and MM5/OSU) and a simple hydrology model, Catchment Moisture Deficit–Identification of unit Hydrographs And Component flows from Rainfall, Evaporation and Streamflow data (CMD-IHACRES) demonstrates the improvement in the characteristics of the streamflow prediction, which may be achieved using CMD-IHACRES. The conceptual structure of CMD-IHACRES allows it to be ‘incorporated’ into the RCMs, improving their streamflow predictions, as is demonstrated for the FIFE region of central USA.

Figure 8: Flow duration curves simulated by the models. Runoff is given by the RCMs run (a) alone; (b) driving CMD-IHACRES with temperature; (c) driving CMD-IHACRES with evapotranspiration; and (d) driving CMD-IHACRES with the regional climate model runoff as effective rainfall.