Beach erosion and marine aggregate dredging: a question of evidence?

摘要

Coastal erosion is a global problem and a major concern for European Union Member States. In the UK, marine aggregate dredging is considered by many to be responsible for coastal loss, and campaigns based on the 'precautionary principle' have been mounted to halt extraction. Two South Wales, UK coastal areas, where critical beach loss has been associated with dredging activities, were monitored to assess morphological change. In five years of beach monitoring along the Penarth coastline (September 1997 to September 2002) and six years of monitoring Port Eynon and Horton beaches (January 2001 to October 2007), no qualitative or quantitative causal link was found between marine aggregate dredging and beach erosion. Conversely, many qualitative and quantitative relationships were established between beach erosion and forcing agents such as water level, wind and waves. Results from Port Eynon and Horton showed significant temporal variations in beach level, and onshore/offshore sediment movement was seen as significant in beach formation processes. At Penarth, changing wind direction and increased easterly storms were most significant. Furthermore, there were indications of recognised causes of coastal erosion, such as increased water levels, storms and anthropogenic construction. Therefore, morphological changes on a relatively short timescale can be clearly attributed to influences other than marine aggregate dredging. Potential future work includes regular monitoring and analysis of shoreline changes in areas adjacent to dredging sites together with concurrent bathymetric surveys. As well as being a strategic approach, it would address stakeholder concern and reduce conflict.