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Title: The Implications of Future Shoreline Management on Protected Habitats in England and Wales
Author: M Lee E
Author: Environment Agency
Document Type: Monograph
Annotation: Environment Agency Project ID:EAPRJOUT_487, Representation ID: 158, Object ID: 1826
Future coastal defence-policies and afnaturala processes will have an impact on habitats within Special Areas of Conservation (SAC), Special Protection Areas (SPA) and Ramsar sites. An overview of the potential nature and extent of these changes (losses or gains):is needed to inform policy decisions on -the alegal and -funding aspects of coastal defence options:and possible habitat replacement, within the context of the Habitats.Directive. This research has involved establishing.the likely area1 changes to habitats within European sites (all .possible, potential, candidate or designated SAC/SPAS) and Ramsar sites -and providing a broad estimate of the costs of replacing any overall net: loss of- habitat.- An assumption was made that habitats will change in response to landform change. Hence, an assessment of the potential coastal landform changes over the next- 50 years has been used to give an indication of the nature- and scale of potential habitat change.-.Predictions of coastal landform change were based on an extrapolation. of what has happened in the. past, but modified assessment of the potential implications of relative sea-level rise. Loss/gain accounts -have been developed for *individual coastal cells in England and. Wales, based on a single abest-guessa coastal defence scenario for the next 50 years (i.e:,do nothing;-hold the line, advance the line: or managed .retreat) identified from a review of available Shoreline Management Plans (SMPs) and. through a series of regional ,workshops. These workshops- were attended .by experienced local staff, from the Environment Agency; English Nature/Countryside Council ,for Wales, Department of the Environment, -Transport and the Regions (DETR); the Welsh Office, RSPB, local Coastal Defence Groups and conservation organisations. The results -give a broad indication, of the nature and scale -of potential :habitat losses and gains. The combined results of ?natural~a and amanageda changes are likely to produce a significant adjustment of landforms and a variety of habitat losses and gains. If the abest-guessa coastal .defence, policies are implemented and if the -predicted coastal changes occur, the following .important habitat changes are possible: i. there could be a net loss .of freshwater. and brackish habitat of around 4000 -ha, primarily. wet grassland (~3200 ha)-but also including significant areas of-coastal lagoon (c500,ha) : 1. and reed bed (~200 ha); ii. there could be a net- gain of intertidal (saltmarsh and mudflat/sandflat) habitats of around-.:-: 2221 ha, with:.the gains associated- with managed retreat (c125OOha) balancing .the expected.losses due to-coastal squeeze and erosion on the unprotected coast; iii. it is estimated -that around 120 ha of sand dunes. could be lost over the next 50 years, primarilyain Northumberland; the .South-west, Cardigan Bay and..on the Sefton coast. Although this represents around only. 1% of the sand dune resource within European Sites in England and Wales, it may involve the loss of a significant proportion of the important foredune dune communities in some areas; iv. there could be a loss of around ,130 ha-of shingle bank habitats representing around 4% of the resource within European Sites in England, and Wales;. R and D Technical Report.WlSO V v. relatively minor losses of cliff top habitats are predicted to occur, in the order of less than 2 ha/year, nationally. The likely costs of freshwater and brackish habitat replacement, on a hectare-for-hectare basis, is estimated to be in the order of and50-60M, at current prices (1998), including site purchase, set-up and on-going management costs. If the site purchase and set-up costs are phased over a 10 year period, the Net Present Value (NPV) of potential replacement costs is estimated to be in the order of and3OM. Some habitats, however, are likely to be irreplaceable (e.g. sand dunes and shingle banks) whereas others may need no more than a simple change of management practice to re-create particular habitats (e.g. arable or pasture to grazing marsh). The report has also drawn attention to the possible need to select and develop replacement sites which are significantly larger than those which were lost, in order to ensure the correct ecological functioning of the habitat. A number of important coastal defence-related issues have been identified which constrain the successful implementation of the Habitats Directive. In summary, the and are: may : the conflict between maintaining the favourable conservation status of the saltmarsh resource through managed retreat, and the resulting losses, in some areas, of freshwater habitats; l saltmarsh re-creation associated with managed retreat may not necessarily lead to the production of habitats that would be integral to a site of international importance; l the flood defence objective of achieving sustainable estuary forms may result in the need for additional managed retreat over-and-above that which was estimated by this study. This would place further pressure on freshwater habitats behind defence lines; l if managed retreat is not implemented on the scale predicted by the workshops, there will be a significant net loss of intertidal habitat; l l l the future management of sand dune and shingle bank systems needs to find an appropriate balance between the need for habitat diversity and flood defence; long-term coastal squeeze is inevitable in front of most existing defences and will place pressure on bird populations, especially those which feed on mudflats and sandflats. A number of specific recommendations have been made: 1. Individual habitat loss/gain accounts should be compiled for each individual European Site, for each of the alternative coastal defence strategies, and organised on a regional basis; 2. A GIS and data management programme should be established to allow the predictions to be modified as and when SMP decisions are finalised or revised; 3. Links should be established with the monitoring programmes currently being developed as part of SMPs, with the aim of compiling records of landform change and habitat loss/gain on, for example, a 10 year basis; R and D Technical Report W150 vi 4. Effoi-t should be directed towards developing. suitable and robust geomorphological and ecological tools for predicting change. Probabilistic methods, for example, may be an appropriate approach to address the.uncertainties inherent in predicting-coastal and habitat: change;. 5. In light of the difficulties in predicting -long-term changes to sand --dunes, it is recommended that a detailed review of the status of dune systems should be undertaken.: This review should consider the potential for future. change within the context of: the sediment budgets and. long-term dune behaviour; 6. Experience of habitat replacement should, be.consolidated and,critically:reviewed in terms of the effectiveness- of the scheme andthe broader environmental::impacts ,The- lessons learnt should be widely disseminated; 7. Field experiments should be undertaken in a range of coastal environments to establish the feasibility of and techniques for habitat replacement in different -parts of England and Wales, with appropriate post project monitoring; 8. Management of dynamic coastlines will result in changes to habitats and associated. species; There is, therefore, a need to identify mechanisms for resolving the potential conflicts between coastal: defence and conservation objectives for intertidal- and freshwater-, designated sites; 9. Following completion- of all SIMPs covering the coast of England and Wales a further review should be carried out to detennine their effectiveness in addressing. theneed to maintain the favourable conservation statusof the European Sites. It may prove necessary to-develop guidance to inform coastal authorities about how the maintenance of the Natura 2000 network should be treated within the SMPprocess. Keywords Habitats Directive, net losses and gains, shoreline management plans, .coastal cells, prediction, coastal defence policies, managed retreat, coastal squeeze; erosion, replacement costs R and D Technical Report Wl.50 vii 1
Publisher: Environment Agency
Subject Keywords: Erosion; Managed retreat; Prediction; Coastal cells; Coastal defence policies; Coastal squeeze; Replacement costs; Habitats directive, net losses and gains, shoreline management plans, .coastal cells, prediction, shoreline management plans
Extent: 61
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