Given the wide range of human uses of the coastline, many of the modern forms of coastal intervention have become multipurpose. Certainly, where new coastal defences have been created, several different types of hard-engineering schemes are used in conjunction. Some opportunities exist to carry this forward on a much larger scale. Within estuaries, for example, tides can be harnessed for electricity generation and barrages can be used for this purpose, along with the creation of new roads and the storage of fresh water. In Britain the idea of putting a barrage across the Severn Estuary has long been mooted, yet it has still not been built. If the scheme were to come to fruition, it would probably be the first of many as similar proposals have been made to dam such diverse stretches of tidal waters as the River Mersey, the Wash and Morecambe Bay