Thinking big : defining resources for major coastal defence projects

The UK’s coastline holds a special place in the nations psyche, but in many places requires significant and ongoing engineering effort to maintain its integrity. A ‘soft’ coastline and strong hydrodynamic regime around the UK, combined with the effects of climate change, contributes to high levels of erosion and sediment transport. Accordingly high volumes of sand and gravel are required for coastal defences, beach recharge and land reclamation every year. The British Geological Survey (BGS), in a project commissioned by The Crown Estate, has been identifying offshore resources which can be used for these applications with the aim of understanding the UK’s capacity for supplying major coastal defence projects. Research has been undertaken using industry and legacy sample data in association with modern high resolution bathymetry. This has allowed the volume of material in significant seabed features, such as sandbanks, to quickly be calculated and their properties defined. Results from this research will help to ensure that materials are sourced from the most cost-effective areas and that supply is not restricted. Understanding the volumes and properties of offshore sea bed features opens up the possibility of new types of coastal management, linking defence with amenity. Large scale coastal engineering schemes, such as the ‘Sand Engine’ on the Dutch coast, shows how these types of projects can both protect the coastline and promote public amenity if the large volumes of suitable material required can be economically and environmentally sourced.