The flood characteristics of large UK Rivers: Potential effects of changing climate and land use

A continuous flow simulation model (CLASSIC) has been used to assess the potential impact of climate and land use changes on the flood regimes of large U.K. catchments. Climate change scenarios, based on the HadCM2 experiments from the Hadley Centre, are applied to the Severn and Thames rivers. The analysis shows that, for the 2050s, the climate change scenarios result in an increase in both the frequency and magnitude of flooding events in these rivers. The various ways of applying the rainfall scenario can have a significant effect on these general conclusions, although generally do not affect either the direction or consistency of the changes. While `best guess' land use changes show little impact on flood response, a 50% increase in forest cover could counter-act the impact of climate change. As would be expected, a large change in the urban cover of the catchments does have a large effect on the flood regimes, increasing both the frequency and magnitude of floods significantly beyond the changes due to climate alone. Further research is required into the potential impacts of seasonal changes in the daily rainfall and potential evaporation regimes, land use changes and the interaction between the two.