In situ stabilization of underwater archaeological sites (WP6)

Sites which are preserved in situ are threatened by the effects of underwater currents which can cause sediment to be removed from sites, leading to their exposure. Upon exposure, sites are susceptible to mechanical abrasion and erosion, which can lead to their total loss. Furthermore, wooden artefacts can, under the right environmental circumstances, be attacked by wood boring organisms such as shipworm, which can also lead total loss of archaeological materials within relatively short periods of time – years or decades rather than centuries or millennia. The EU supported project Wreck Protect (http://www.wreckprotect.eu) assessed ways to protect historical wooden shipwrecks in situ from the threat of wood boring organisms. An extensive review of methods used in the offshore and timber industries, along with coastal engineering and archaeological / conservation showed that the most cost effective, environmental friendly methods to protect archaeological wood relied upon limiting the access of oxygen to the wood and this can most simply be achieved by covering with sediment. However, simply covering with sediment may not be sufficient as it may itself be washed away. The more innovative methods identified actually took advantage of currents and sediment transport within the water column to either entrap sediment and create a burial mound or disperse currents so that seabed erosion was reduced. Partner 5, (SSCS) is a world leader in scour control systems to prevent seabed scouring and erosion for the offshore industry (gas and oil pipelines, offshore wind turbine footings). To achieve this they use mats of artificial sea grass, which float upright in the water column and entrap passing sediment particles, effectively creating an artificial seabed. These mats will be developed further to test their applicability to protecting shallow water submerged archaeological sites, which are under threat from near shore and coastal erosion. Furthermore, the durability of materials that have typically been used to stabilise submerged archaeological sites in the marine environment, including sandbags, plastic sheeting, geotextiles and debris netting, will be tested.