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 impactof climate and land use changes on the flood regimesof large U.K. catchments. Climate change scenarios,based on the HadCM2 experiments from the HadleyCentre, are applied to the Severn and Thames rivers.The analysis shows that, for the 2050s, the climatechange scenarios result in an increase in both thefrequency and magnitude of flooding events in theserivers. The various ways of applying the rainfallscenario can have a significant effect on thesegeneral conclusions, although generally do not affecteither the direction or consistency of the changes.While best guess land use changes show little impacton flood response, a 50% increase in forest covercould counter-act the impact of climate change. Aswould be expected, a large change in the urban coverof the catchments does have a large effect on theflood regimes, increasing both the frequency andmagnitude of floods significantly beyond the changesdue to climate alone. Further research is requiredinto the potential impacts of seasonal changes in thedaily rainfall and potential evaporation regimes, landuse changes and the interaction between the two.