Decisions about investments such as flood alleviation schemes are nearly always based on analysis of information from the past. We assume that past hydrological conditions will be a reasonable guide to what will happen in the future, usually with some adjustment to allow for the possible impacts of climate change. This assumption is becoming increasingly hard to believe given the frequency of severe flooding in some parts of the UK over the past 10-15 years.
This presentation describes the application of innovative hydrological methods that break free from the assumption that past floods all follow the same statistical distribution. The results of this non-stationary flood frequency analysis for some rivers in Hampshire, Cumbria and elsewhere show that flood flows for a given probability can be significantly underestimated by conventional methods of flood frequency analysis.
We cannot assume that past trends will continue. But if the change in flood probability is modelled using information from a physical variable, rather than being related to time, then it would be possible to incorporate climate change scenarios to help better understand future flood risk. The results have important implications for the appraisal and design of flood protection schemes.Back to all speakers