Restoring Saltmarshes with drag box solution

60% of the Saltmarsh habitats around the UK have been lost since 1945, and without some inspired interventions significant further losses will continue, fuelled by coastal squeeze (development), increased wash from boats, extreme climatic events (climate change influences) and rising sea levels.

Land & Water, alongside the new sister company Earth Change, (which was set up to optimise the natural capital solutions for distressed land), has re-invented a drag box solution dating back to the early 1900s to restore the UK’s Saltmarshes, with the first full-scale trails, permitted by the MMO (Marine Maritime Organisation), completed in March 2023.

Saltmarshes provide incredible environmental benefits including acting as a natural flood defence, an absorbent of harmful nitrates and phosphates and a haven for wildlife to increase biodiversity.

Land & Water, and Earth Change, have partnered with Chichester Harbour Conservancy as part of the Solent Seascape Project for trials to restore the saltmarsh in Chichester Harbour. The need to restore this valuable environment follows the loss of 250ha of Saltmarsh in Chichester alone since 1945.

The UK dredges approximately 20 million tonnes of silt and mud a year maintaining our ports, harbours and marinas. The majority of this material is disposed of offshore, in designated disposal sites. The new technology allows this valuable resource to be reused for an environmental gain, and crucially “at scale”.

Restoring Saltmarshes within an intertidal habitat is not straightforward. The large barges and ships used in commercial dredging operations cannot directly access the shallow waters and mudflats where Saltmarsh proliferates.

The use of the drag box enables the larger vessels to deposit their muddy cargoes close to the Saltmarsh at high tide, for retrieval once the tide has ebbed away.

Also, the drag box methodology was used by Victorian engineers to dredge lakes, dragging a skid between two traction engines to recover silts and sediments ashore.

Land & Water has borrowed modern hydraulic winching technologies from the Canadian Forestry Industry, coupled with a new/enlarged drag box design to enable the efficient recovery of large quantities of sediment in very short timescales, and with negligible environmental impact.