The Regional Habitat Compensation Programme (RHCP) is a strategic programme run by the Environment Agency. In the Solent and South Downs area, the Eastern Solent Coastal Partnership (ESCP) is leading the RHCP on behalf of the Environment Agency. The Solent and South Downs RHCP covers the area from Hurst Spit in the west to Beachy Head in the east and includes the north coast of the Isle of Wight.
The RHCP seeks to replace habitats that are lost due to coastal squeeze or tidal inundation effects that arise from the management of coastal defences. Coastal squeeze occurs when a hard defence structure prevents the landward migration of intertidal mudflat and saltmarsh habitats with sea level rise and the habitat is therefore ‘squeezed’ against the hard defence and eventually lost (Figure 1). Tidal inundation of coastal and freshwater habitats occurs when sea level rise over-tops or breaches a defence and floods a site with seawater – this can happen naturally (unmanaged) or as a result of a planned (managed) realignment of defences.
Figure 1: Coastal Squeeze
Habitat Compensation Targets
The habitat types that are relevant to the Solent and South Downs RHCP are:
- Intertidal mudflats
- coastal grazing marsh
- freshwater habitats
- saline lagoons
The ESCP has provided an update on the habitat compensation targets for the Solent and South Downs RHCP by reviewing and combining the requirements from the three relevant Shoreline Management Plans (SMPs): North Solent, Isle of Wight and Selsey Bill to Beach Head. Over the 100 year SMP period, the Solent and South Downs RHCP needs to create:
Table 1: Habitat creation targets for the Solent and South Downs RHCP area (2005 to 2105)
This strategic update is the first part of a three-stage approach to the RHCP. The second stage involves prioritising sites, programming, undertaking further analysis and funding considerations. The third stage is the delivery of habitat compensation schemes and site implementation.
Completed habitat compensation schemes
Several habitat compensation schemes have already been completed in the Solent and South Downs area. These are described below:
Lymington Water Level Management Plan
Implemented in September 2010, this compensation scheme re-established tidal exchange in the Lymington River through the introduction of self-regulating tide gates at the Bridge Road crossing. The reedbed increased upstream and laterally as willow scrub died back and woodland retreated 5-20 metres inland. The reedbed cover increased from 40% in 2009 to 90% in 2014. Rank fen vegetation and nettles died off as a result of saline inundation. Invasive non-native species present in 2009 were largely removed from the reedbed by 2014. Overall, this compensation scheme created 21 hectares of tidal reedbeds upstream of the bridge.
Medmerry Managed Realignment Scheme
Completed in 2013, this compensation scheme created 183 hectares of new intertidal habitat comprising of 158 hectares of saltmarsh and 25 hectares of mudflat. It is the largest open coast managed realignment scheme in Europe. In addition to the intertidal habitats, there are also reedbeds and freshwater ponds and ditches that provide habitat for water voles and aquatic invertebrates. The is managed as a nature reserve by the RSPB and has already seen increasing populations of breeding and wintering wildfowl and wading birds - a highlight was a pair of black-winged stilts successfully breeding in 2014.
Manor House Farm
This site in the lower Test Valley was identified as a potential area to create floodplain grazing marsh and other wetland habitats. It is predicted to create 69 hectares of freshwater habitats. With sea level rise and increasing tidal influence, this will eventually become coastal grazing marsh together with an additional 16 hectares of freshwater habitats (such as ponds, reedbeds and wet woodland). The creation of these habitats will reduce the RHCP target for coastal grazing habitat from 76 hectares to 7 hectares and there will be a net gain of 12 hectares of freshwater habitats.
Potential Future Habitat Compensation Opportunities
There is still an urgent need for habitat compensation to meet the remaining RHCP targets. Following the implementation of the completed schemes listed above, the remaining habitat compensation targets for the Solent and South Downs area are:
Table 2: Outstanding habitat creation targets for the Solent and South Downs RHCP area
The Solent and South Downs RHCP is currently focused on creating saltmarsh habitat as there is an urgent need to create an additional 20 ha of this habitat type in the current epoch and saltmarsh is predicted to have the greatest area of loss over the next 100 years. Saltmarsh provides important feeding grounds for birds, nursery areas for small fish and habitat for rare invertebrate species.
The RHCP has identified potential sites in the Solent and South Downs area for saltmarsh habitat creation opportunities. These sites have been prioritised based on how likely it is that they could be implemented as there are many barriers to managed realignment, such as the physical characteristics of the site, landowner concerns, opposition from communities, presence of infrastructure and/or utilities and the potential loss of important landward freshwater habitats and bird roosting sites. The ESCP is working with the Environment Agency to progress the best sites for habitat creation.
Meeting the habitat creation targets in the Solent and South Downs RHCP is a legal requirement and is essential to ensuring that flood and coastal protection schemes can continue to be delivered for communities in our area.
For more information about the Solent and South Downs RHCP, please visit the Southern Coastal Group website here. For more information on protecting coastal wildlife and habitats please visit the Environment Agency's website using the related links section of this page.
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