The morphology and sedimentary processes of the seabed play a critical role in the distribution of benthic habitats, which form an integral part of much of ocean life. For this assessment we have brought together data from many sources, including research programmes and commercial surveys.

In areas of relatively rapid coastal erosion, rates of change are being monitored. Offshore, there are several means of mapping the seabed. Multibeam Echosounder Systems (MBES; Figure 2.5) provide a new approach, and MBES data collection programmes have expanded dramatically since Charting Progress. We now have new measurements from all regions using MBES, although as of 2008 MBES data cover only about 15% of the UK seabed.

As yet we have little information from very shallow waters, where surveying is slow (the rate of coverage is proportional to the water depth) and therefore cost has limited progress. However, the coastal zone is so important in relation to erosion, flooding, habitats, and commercial uses, that this is a key area for future work.

In offshore areas, the rate of change of the seabed is generally low; rapid changes are restricted to shallow areas where wave action is strong or human activities take place (e.g. trawling, aggregate extraction and dredging). Erosion (excluding hard-rock coasts) is occurring along 17% of the total UK coastline (30% of England’s coastline; 23% Wales; 20% Northern Ireland; 12% Scotland ). Almost two-thirds of the intertidal profiles in England and Wales have steepened over the past 100 years, as rising sea levels have taken waves closer to the base of hard defences or erodible cliffs. Steepening of the intertidal profile is particularly prevalent on coasts defended against erosion (this represents 46% of England’s coastline; 28% Wales; 20% Northern Ireland and 7% Scotland).

To underpin future marine planning and to support commercial exploitation and legislative drivers such as environmental monitoring and conservation, we now need more high-quality bathymetric data and to match this with analysis of the geology and habitats, so forming coherent maps and models. We should optimise use of the several existing UK programmes that collect MBES data for a wide range of different uses (unlike Ireland, for example, which has a single integrated marine mapping programme). Better integration of Government-funded surveys is being achieved through: the Civil Hydrography Annual Seminar (CHAS) meetings organised by the Maritime and Coastguard Agency (MCA); a Memorandum of Understanding between several public sector organisations to share data; and several initiatives to collaborate in the collection and interpretation of data (e.g. Channel Coastal Observatory and MCA; NERC research centres and others). Adding commercial data, and further collaboration between programmes building on the Civil Hydrography Programme, would help in developing marine renewable energy and meeting the challenges of the EU Marine Strategy Framework Directive.