A regional investigation of climate change impacts on UK streamflows

A framework has been developed that enables the estimation of climate change impacts on flow regimes of catchments in England and Wales. Within this framework, rainfall-runoff processes are represented by a unit hydrograph-based model that was calibrated against historical data from 39 catchments. Rainfall and temperature inputs were perturbed according to an equilibrium climate change scenario. Three study catchments, of widely differing flow regime, are presented as examples of the versatility of the model, and to illustrate variations in catchment response under the modified climate. Results, quantified by percentage change in low, mean and flood flows, were interpolated spatially to provide a regional picture of hydrological response. Catchments in central and eastern England suffer the most severe reductions in low flows whilst flooding is seen to increase in the north and west. The linking of model parameters to physical landscape characteristics allows estimation of flows, both historical and climate-changed, at ungauged sites. Since these characteristics include land use indices, it is possible to quantify second-order effects resulting from changes in land use.