Exploring patterns of current and future residential flood risk in Great Britain

Abstract

In previous assessments of UK flood risk, flood hazard has often been poorly represented by low skill models. Meanwhile, assessments of future flood risk have lacked a detailed representation of future flood exposure. This study represents a significant step forward in both flood hazard and future exposure representation. Using a state-of-the-art climate-conditioned hydrodynamic model for fluvial, pluvial and coastal flooding (Bates et al. (2023)) paired with the latest UK-SSP population projections (Pedde et al. (2021)), we explore how climate-induced changes in flood hazard interact with increasing exposure due to population changes.

Our model values current yearly residential economic floods losses at £840 million, with fluvial flooding accounting for approximately 80% of these. This flood risk is not borne equally between the devolved British nations, however. In Scotland and Wales approximately 30% of local authorities have over £100 of annual flood losses per property, whereas only 4% of local authorities in England experience such levels. Under a high emissions climate scenario (RCP 8.5), by 2070 we estimate flood risk will increase by 29% whilst under a low emissions scenario (RCP 4.5) flood risk will increase by 10%.

Whilst climate change is set to drive an increase in flood risk over the next 50 years, our study suggests that population dynamics may have potential for offsetting relative flood risk rises. In all SSP projections studied, an increase in population drives an increase in the yearly rate of property inundations. However, due to population growth predominantly occurring in low flood risk areas, we see a decrease in relative flood risk. Despite these decreases in relative flood risk, due to population change, when paired to climate change, we still see significant increase in flood risk over the next 50 years. Consequently, low emissions scenarios, such as SSP1/RCP2.6, see the lowest increases in flood risk.

Date of Award	6 Dec 2022
Original language	English
Awarding Institution	University of Bristol
Supervisor	Maria Pregnolato (Supervisor), Francesca Pianosi (Supervisor) & Paul D Bates (Supervisor)