Energy and Climate Change CommitteeWritten evidence submitted by Rose Hewlett (SEV26)

Thank you for inviting submissions in respect of A Severn Barrage. I am a local historian living in the upper Severn estuary. I am neither for nor against a Barrage.

The Severn has one of the most unmanageable estuaries in the world. To try to manage it with a Barrage requires modelling, and for that modelling to be realistic it requires accurate data. At the present time, I believe there is insufficient accurate data available, particularly in respect of the area upstream of the First Severn Crossing.

This was exposed in the Severn Estuary Shoreline Management Plan Review which admitted that no account had been taken of the fluvial flow or the tidal bore and that very little sediment data existed upstream of the First Severn Crossing. These three things are amongst the most important in shaping our shoreline and managing flood risk in the upper estuary, and yet no effort was made to overcome this lack of knowledge.

Unfortunately, this knowledge gap looks set to be repeated by the promoters of the Cardiff-Weston Barrage who admit to a lack of detailed understanding of the movement of silt and mudflat deposits throughout the estuary.

The upper estuary will be greatly affected by a Barrage. It is essential that its present dynamics (migration of the main channel, currents, patterns of erosion and accretion, sediment budget and ever-shifting mudflats and sandbanks) are fully understood so that a reliable baseline can be set. This is the only way that the effects of a Barrage will be properly understood.

My research involves studying historical records, site visits and anecdotal evidence. There seems little place for any of this in an age of desktop studies and yet, as has been proved in my own area of study, local knowledge has successfully managed flood risk for centuries because people watched the behaviour of the river and acted accordingly.

So my plea to the Select Committee is that they ensure that the promoters of the Cardiff-Weston Barrage undertake the research necessary to understand the dynamics of the estuary upriver of the First Severn Crossing and that they consult with the local people all along the banks to Gloucester to increase their knowledge.

November 2012