UK. Sediment tracer study assists nearshore beach replenishment trial

Wednesday, 06 May 2015

Fugro is participating in a nearshore replenishment trial that aims to reduce the cost of beach maintenance. Sustaining Poole Bay’s wide sandy beach is hugely important for the protection of seafront properties and infrastructure against regional coastal flooding and erosion.
Maintaining these sands has historically relied on traditional replenishment schemes; dredging material from the harbour and physically pumping or spraying this ashore. In December 2014 the Borough of Poole spent around £2 million carrying out such works.
A nearshore replenishment trial is now underway with the aim of determining if dredged material which is deposited offshore, naturally makes its way to the beach, thus eliminating the need for costly mechanical pumping and land operation to reduce the cost of beach maintenance. To assist in this trial, Fugro released 1,000 kilograms of tracer sand approximately 400 metres offshore. This tracer material was placed on top of the deposited sand as part of the trial. It closely matches native sand characteristics but has been coloured to allow detection and tracking of its movement.
Following the release of the fluorescent tracer material, Fugro is conducting a survey to collect sediment samples from the seabed and beach in the region around the deposit zone. The movement of the fluorescent particles is tracked through a campaign of sediment sampling.
Dr Travis Mason of the Channel Coastal Observatory stated, ‘Fugro’s tracer technique has been shown to be an effective means of tracking sediment movement at this site. At Poole Bay, tracer material has been observed at both offshore and onshore locations, making a significant contribution to our understanding of how dredge material behaves when deposited off the beach.’

If onshore movement of the material could be proved, significant cost savings can be made in future by utilising natural, onshore wave action to carry sediment ashore, thus providing continued protection for this stretch of coastline.
Fugro has employed this type of sediment tracer technique at various locations in the UK for a wide range of clients. The fluorescent tracer material is painted with a UV-responsive pigment and then coated with a clear lacquer to retain the fluorescent characteristics over transport distances in excess of 1,000 kilometres. In low quantities, when mixed with natural sediments, tracer material is difficult to observe with the naked eye but may be detected under a UV light. This type of tracer technique can be adapted to suit a wide range of environmental conditions. Various UV-responsive colours are available and can be used to track the movements of various fractions of sediment for more in-depth analyses.
Fugro creates value by acquiring and interpreting earth and engineering data and providing associated consulting services to support clients with their design and construction of infrastructure and buildings. Fugro also supports clients with the installation, repair and maintenance of their subsea infrastructure.
Fugro works around the globe, predominantly in energy and infrastructure markets offshore and onshore. It employs approximately 13,500 employees in over seventy countries. In 2014 Fugro’s revenue amounted to EUR 2.6 billion; Fugro is listed on Euronext Amsterdam.

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Last Updated ( Wednesday, 06 May 2015 )