Saltmarsh can migrate landward as sea level rises over time. This is because plants and animals can naturally adapt to increasing water levels, where there are no barriers preventing this, thereby maintaining the extent of the saltmarsh and its function.
Where man made structures have been built to protect communities from coastal flood and erosion risks, such as sea walls or rock revetments, the habitat may be prevented from moving landward as sea level rises, and it is squeezed up against these defences. This is known as ‘coastal squeeze’ and means the extent and functioning of the saltmarsh reduces over time, along with the habitats and species that it supports. In places, we cannot prevent this, as we are required to protect large communities from coastal flooding and erosion.
A lot of work has been undertaken to predict how much saltmarsh will be lost over the next 100 years in the Solent region, due to coastal squeeze. The Environment Agency’s Regional Habitat Creation Programme has assessed these losses and identified potential sites for the creation of new saltmarsh habitats. One way of doing this, is to actively remove historic sea walls, which are acting as barriers to saltmarsh migration. This is often referred to as ‘managed realignment’, where defences may be built to a lower extent, further inland, thereby preventing coastal squeeze, but still protecting the communities behind.
Further information is available on this website about managed realignment and the Regional Habitat Creation Programme.
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