By providing essential resources to replenish beaches, well managed and regulated marine aggregate extraction can represent a solution to coastal erosion rather than the cause of it. Such erosion is a natural process, driven by waves and currents that affect both beaches and cliffs.
One of the industry’s key objectives is to ensure that dredging does not affect such processes; for example by changing the wave climate or interfering with seabed sediment transport. Before a Marine Licence to allow dredging is granted, careful analysis of waves and currents in the area is undertaken using hydrodynamic models. Modelling is combined with an assessment of sediment transport to ensure that pathways to beaches or along the coastline are not disrupted.
Although dredging often occurs large distances offshore - eight kilometres or more - and commonly in water at least 20 metres deep, the industry is required to carry out detailed studies to determine the possible influence of dredging on natural processes. A conservative approach exaggerates the potential effects of dredging and consequently over-estimates the possible impact. A Marine Licence would not be issued if the regulators or their advisors considered the proposals would result in unacceptable impacts to the coastline or any adjacent sandbank features which protect it.
To provide further confidence in the conclusions of the environmental impact assessment process, monitoring of the seabed and adjacent coast in sensitive areas may also be undertaken while dredging is carried out to validate the impact predictions made.
In 2013, a guidance note entitled 'Marine aggregate dredging and the coastline' was published by BMAPA and The Crown Estate. This built on well established approaches for assessing coastal impacts, and established best practice for the British marine aggregate industry by advising on the scope, standards and transparency that are expected in the Coastal Impact Studies (CIS) undertaken as part of the wider environmental impact process. It is designed to be a valuable reference providing mutual benefit to all stakeholders and consultees, including dredging companies, consultants, government regulators and agencies, local authorities, NGOs, other seabed and coastal users and the public. Both defended and natural coastlines are considered through this process.
To ensure consistency, the guidane note outlines the terms of reference and essential elements of a CIS; including the data required to undertake a study, key components and their analysis, consideration of cumulative and in-combination impacts, as well as mitigation and monitoring options.
With the growing influence of climate change and increased storminess, the profile and awareness of local changes occurring along the coastline has never been higher. This can sometimes lead to the view that the changes being observed are influenced by the extraction of marine sand and gravel, despite the fact that dredging takes place in licensed areas well offshore and there are no physical processes that link it to the natural erosion of the coastline that has been occurring since prehistory.
In response to these perceptions, BMAPA and The Crown Estate have produced a series of regional brochures to describe the geological evolution of local coastlines, the geological origins of the offshore sand and gravel resources that are being dredged and the influence of the modern day waves and tides on both these deposits and the coastline. Information is also provided about the scale of marine aggregate dredging that is taking place, how the activity is assessed, regulated and monitored and how similar activities are controlled in other European countries.
These regional brochures are available to be viewed below. Alternatively hard copies may be requested by contacting firstname.lastname@example.org
Aggregate dredging and the Suffolk coastline – a regional perspective of marine sand and gravel off the Suffolk coast since the Ice Age
Aggregate dredging and the Norfolk coastline – a regional perspective of marine sand and gravel off the Norfolk coast since the Ice Age
Aggregate dredging and the Humber coastline – a regional perspective of marine sand and gravel off the Holderness and Lincolnshire coastline since the Ice Agel
You can get an expert view on the issue of whether dredging affects coastal erosion by watching a specially commissioned BMAPA video.