Rock armouring/revetments • Rock barriers

Case Studies	South Ferriby, Goxhill and Barrow Haven, Humber Estuary
	Lymington River

As discussed earlier, there has been a move away from hard engineering techniques which aim to halt erosion and/or promote accretion to softer techniques which aim to work with natural processes. However, although these techniques are receiving less attention, they could be used in the future on a smaller scale based on the site specific circumstances (and potentially in combination with sediment recharge or vegetation planting). In the past, such techniques have included:

Rock armouring/revetments

Rock armouring or revetments have been used to halt lateral erosion at the leading edge of the saltmarsh and in creeks. They protect the cliff edge from mass failure by providing protection from wave action and tidal currents, but will limit the ability of the marsh to evolve or respond to changing forces, such as sea level rise.

Historically, this form of protection has been undertaken on the Humber, Severn Estuary and in the Wash. Click on the above link for a more detailed case study.

The use of soft revetments has also been employed where rolls of coconut matting (coirs) have been placed along the eroding saltmarsh cliff face. This largely experimental technique was implemented on Lymington marshes with limited success. Click on the above link for a more detailed case study.

Rock barriers

Rock barriers work in a similar way to sedimentation fences, in that they combat erosion by reducing wave energy and tidal currents, and produce calm water in their lee which enhances sedimentation. They can, however, have a significant ecological, hydrodynamic and landscape implications.