Probabilistic impacts of climate change on flood frequency using response surfaces I: England and Wales

Abstract

The impacts of climate change on hydrology are an important focus of research around the world, but use of large ensembles to drive impact models is not necessarily straightforward and has to be re-done when new projections are released. Here an alternative sensitivity framework approach is demonstrated, using a set of typical response surfaces alongside the probabilistic UK Climate Projections (UKCP09). These projections comprise sets of 10,000 changes in a number of variables, available for 10 river-basin regions covering England and Wales. Estimates of the potential range of impacts on 20-year return period flood peaks are presented for different types of catchment in each region. Regional average impact ranges are compared for a number of time-horizons and emissions scenarios. Results show clear differences in impacts between catchments of different types and between regions. South-East England has the highest impacts with the greatest uncertainty range, while the Dee region has the lowest impacts and smallest uncertainty range. Regional differences are due to both spatial differences in projections and a differing regional balance in the number of catchments of each type. Ease of application of multiple projections is a clear advantage of this sensitivity-based approach to impact assessment, which could be extended to other regions and sectors.

An assessment of the potential for natural flood management to offset climate change impacts

“…Maps summarising the studies listed in supplementary table S1 by (a) the effect they showed on peak flows and (b) whether they were based on observed or modelled data. High), were processed and overlaid on the representative flood response surfaces, and corresponding sets of flood impacts extracted (Kay et al 2014a(Kay et al , 2014b. Here the impacts on 50 year return period flood peaks are used, as the current Environment Agency guidance on climate change and flood peaks is based on these values (Reynard et al 2017).…”

“…These decision trees were applied to each catchment in the National River Flow Archive (NRFA; nrfa. ceh.ac.uk), to provide information on the spatial distribution of flood response types across Britain (Kay et al 2014a(Kay et al , 2014b; supplementary figure S2). Extra uncertainty allowances were also derived for each response type (Kay et al 2014c).…”

Hydroclimatology of extreme river flows

“…Reynard et al ., ; Prudhomme et al ., ; Booij, ) and regions (e.g. Bell et al ., ; Garcia‐Ruiz et al ., ; Kay et al ., ,b). In addition, Lehner et al .…”

Global Climate Model Selection for Analysis of Uncertainty in Climate Change Impact Assessments of Hydro-Climatic Extremes

“…Hybrid selection approaches have been proposed consisting of a combination of two or more of these methods, while sensitivity-based methods have been used for generating climate impact response surfaces for which projected changes in climate variables can be directly translated into impacts [12].…”