CHANGING FLOOD PEAK LEVELS ON THE RIVER THAMES

Peak water levels recorded at locks along the Thames over the past one -hundred years were analysed using cumulative deviations from the mean to identify patterns and trends in hood events. There has been a near ly constant rate of occurrence of hood events above a bank-full thresh old, although a greater number of extreme events occurred in the first half of the record, i.e. before 1940. Catchment rainfall preceding th ese extreme events was found to have significantly higher intensities on a daily basis than that preceding hoods with lower peak levels. For much of the river, the relationship between event duration and peak w ater level has not changed significantly since the 1890s. Channel dred ging and hood prevention schemes have resulted in a localized decline in peak flood levels and event duration.