The Severn Bridge spans the Severn estuary, a mile wide stretch of water proposed for the Severn Barrage, for hydro power electricty near the Severn second crossing which links england with south wales. If the barrage is built there is a enhanced flood r

The Severn Bridge spans the Severn estuary, a mile wide stretch of water proposed for the Severn Barrage, for hydro power electricty near the Severn second crossing which links england with south wales. If the barrage is built there is a enhanced flood risk on the seaward side because only a proportion of the water that presently flows up stream will pass through the barrage leaving the remainder to rise up outside, possibly raising levels by as much as a metre, which could also see low tide mud flats lost. (Photo by Steven Allen/Construction Photography/Avalon/Getty Images)