Severn Estuary ForumFlood Risk and the Severn Barrage19th September 2009 Nick Lyness Wessex Flood &Coast Erosion Risk Manager
Climate change impacts drainage coastal development channel morphology UPSTREAM DOWNSTREAM defences habitat de-commissioning
Flood Defence issues A barrage should decrease overall flood risk from storm surges, but…… Existing defences, and new strategies, will manage the flooding impacts of climate change without a barrage. SDC report recognises that flood risk is an emotive subject, but it is not a show stopper or promoter.
Tidal flap valve at Windmill Reen, Redwick Blackwall West Reen, Magor Seawall near Goldcliff Point
Flood Defence issues A barrage should decrease overall flood risk from storm surges, but…… ~ 100 drainage schemes will need upgrading. Up to £60m to sort the pumping stations and tidal outfalls Thousands of people are protected by defence systems
De-commissioning Effective life of the barrier 100 yrs? 200 yrs? For the foreseeable ever? Higher seas, bigger seas - how effective is it? Climate change impacts? Coastal development behind the barrier - depending on barrier Who maintains the “defence”?
Our view Nature and scale of barrage proposals would cause irreversible impacts to features, species and habitats. Direct impact on Severn Estuary Special Protection Area (SPA), proposed Special Area of Conservation (pSAC) etc. Difficult to envisage how required compensatory habitats could be provided to replace those that would be lost. The case for a barrage needs to take account of other renewable options which might give similar benefits, at lower financial and environmental cost.
Shad Facts • No breeding populations of Allis shad known in UK • Only 4 sustainable breeding populations of Twaite shad known in UK AND 3 are in the Usk, Wye & Severn (the 4th is in Tywi) • All are SAC Listed
Our view Major environmental impacts due to the vast amounts of materials required. Discharge consents / permits would need reviewing. Substantial ancillary and infrastructure development including the need to modify or build new port facilities. Lots of work to understand how the proposal would fit with the requirements of the Water Framework Directive. A major programme of predictive environmental studies will be needed, which could take several years to complete.
Nick Lyness Wessex Flood &Coast Erosion Manager Thank you