Improving flood risk assessment in flashy catchments under a changing climate

My PhD will build on previous work at Newcastle University which had collected sub-hourly rainfall data from gauges across Great Britain and used this to re-analyse rainfall event profiles resulting in derivation of six hyetograph shapes for the purpose of updating design rainfall profiles. My PhD initially aims to investigate extreme rainfall events to assess how rainfall profile shapes are related to temperature, in order to use this as an indication of the effect climate change may be expected to have on future rainfall. In addition to the assessment of observed rainfall data from the collected gauge records, my PhD will also analyse and compare rainfall profiles from convection permitting model simulation results. Advances in climate modelling have enabled high resolution models which can represent small-scale effects such as convection in clouds and thus give more accurate predictions. Although computational requirements mean this is more limited to local areas than globally, this is acceptable for my PhD which is focussed on Britain. The next stage of the PhD will be to use ReFH2 software to derive flood hydrographs from the updated rainfall profiles six design hyetograph shapes and compare them to the existing two hyetograph shapes from the Flood Studies Report (FSR), which are the current standard shapes for hydrological analysis in Britain. The two FSR profiles both have a symmetric, single-peaked bell-shape, which does not vary with storm duration or location but has a broader, lower shape for winter storms, and a peakier, higher shape for summer storms. The six updated profiles comprise three horizontal variations of front-loaded, centre (symmetrical) and back-loaded shapes and two vertical variations giving more-peaked and less-peaked versions of each of the profile loadings. The flood hydrograph testing will be predominantly focussed on small, flashy catchments since these are most responsive to rainfall events, in particular short, intense rainfall which is likely to be highly affected by climate change. It is anticipated that approximately 20 catchments will be tested, using descriptor data from the Flood Estimation Handbook (FEH) web service. The last stage of the PhD will be to apply the rainfall profiles in hydrological and/or hydraulic model simulations, such as Newcastle's SHETRAN, CityCAT or HiPIMS software, to assess the effect of the different profile shapes on flood risk. If time allows, further simulations will be undertaken with the model terrain adjusted to reflect natural flood management interventions with the aim of assessing how best to adapt catchments for the effects of climate change. It is proposed to undertake a review of methods used in the literature to apply climate change in flood risk estimation in order to inform application of climate change for my PhD. The outputs of this PhD will provide an update to current understanding of flood risk and hence help inform application of appropriate design storms for future flood management projects and potentially contribute to guidance for flood risk assessment on relevant scenarios to test.