Estimation of future coastal flood risk in the Severn Estuary due to a barrage.

The Severn Estuary is an ideal site for tidal renewable energy projects and the probability of coastal flood risk in the estuary will increase accordingly due to climate change. Therefore, it is significant to predict the future status of coastal flooding in this estuary using various scenarios with the effects of climate change and potential barrage construction. An existing two-dimensional hydrodynamic model is outlined first. Three scenarios at the open seaward boundary are then presented. Finally, the model was used to simulate the hydrodynamic processes in the estuary using three boundary scenarios. Simulated results show that (i) without the barrage, the maximum levels along the estuary could rise by 1.0-1.2 m due to sea-level rise, and the effect of extreme sea levels on the distribution of maximum water levels would be noticeable only in the outer estuary reach; (ii) with the barrage, the maximum water levels could reduce by 0.5-1.2 m upstream of the barrage even if a sea-level rise of 1.0 m would occur by 2100, and extreme sea levels could not influence the distribution of maximum water levels upstream of the barrage; and (iii) the future flood risk in a small coastal floodplain would increase and the potential losses could reach £6.5 M/year due to sea-level rise without the barrage, and it could be avoided completely if the barrage were to be constructed as proposed. [ABSTRACT FROM AUTHOR]