December 2010
Halcrow’s coastal team have completed a major study which has identified that in some parts of the UK, beaches can be maintained naturally under rising sea levels. The study is known as CETaSS – Cell Eleven Tide and Sediment Study.
The CETaSS work assessed the impacts of sea level rise and climate change specifically on the coast of north-west England and north-east Wales, from the Great Orme in North Wales to the Scottish Border.
Large areas of land and thousands of properties near this 560 kilometre of shoreline are at risk of flooding or erosion. In many locations coastal defence depends upon extensive inter-tidal areas but there is uncertainty over future extent of these areas.
The study included modelling of waves, tides and sediment transport under present day and future conditions.
A key finding was that the strong tidal currents drive onshore sediment movement throughout the region. In most areas increases in wave height and mean sea level were shown to increase the potential for sediment to be transported towards the shore.
Dr Nigel Pontee, Halcrow’s project manager, explained the importance of this:
“The results suggest that for most of the coast there is a mechanism for beaches to be maintained under rising sea levels. This is important because beaches assist in dissipating wave energy and reducing the exposure of defences. This is also good news for the large areas of the intertidal zone designated under the European Habitats Directives. ”
The study findings have been used in the development of the Shoreline Management Plan (SMP) for the region, which is being led by Blackpool Council on behalf of the North-West England and North Wales Coastal Group.