Introduction to 'Coastal Squeeze'

A 'fixed' landward boundary is often associated with habitat loss including infrastructure development (roads, housing industry, ports and harbours etc.). In tidal areas, especially saltmarshes the landward margin may have been moved seaward as enclosure has taken place. Both of these activities result in a direct loss of habitat.

Comment: Information about these losses is available via links to the pressures influencing each of the habitats included in the Guide.

In areas where relative sea level is rising the rate of isostatic adjustment either reinforces or fails to counteract eustatic change. The term 'coastal squeeze' is applied to the situation where the coastal margin is squeezed between the fixed landward boundary (artificial or otherwise) and the rising sea level. In areas where sediment availability is reduced, the 'squeeze' includes a steepening beach profile and foreshortening of the seaward zones. The factors effecting an estuarine squeeze are shown in the figure below, after (Doody 2001).

Comment: This 'squeeze' is most often applied to tidal habitats, mainly in relation to eroding saltmarshes, though the term can be used to describe the loss of other habitats where the landward position is fixed and erosion at the seaward margin is taking place. Similarly deltas may be affected as sediment supply is reduced and erosion at the margin takes place as, for example, is the case in the Ebro Delta in Spain.

References

Doody, J.P. 2001. Coastal Conservation and Management: an Ecological Perspective. Kluwer, Academic Publishers, Boston, USA, 306 pp. Conservation Biology Series, 13