Solent Dynamic Coast Project
The Solent Dynamic Coast Project (SDCP) was conducted to inform development of the North Solent Shoreline Management Plan (SMP) to ensure compliance with the requirements of the European Union Habitats and Birds Directives. The focus was on mudflat and saltmarsh habitats as these form the largest expanse of coastal habitats across the north Solent that are immediately under threat from climate change and coastal management decisions. The consequent effect to coastal grazing marsh was also considered.
The main objectives were to;
· clarify legal drivers and liabilities to provide information to planning authorities on the need to preserve inter-tidal habitat creation sites for their purpose.
· quantify the amount of inter-tidal coastal squeeze over the next 100 years that requires replacement habitat
· identify sites where inter-tidal habitat creation is physically possible
· quantify the amount of inter-tidal habitat creation sites that could potentially offset intertidal coastal squeeze over the next 100 years
· undertake preliminary ranking and assessment of the feasibility of conducting managed re-alignment relative to other impacting variables
· develop a region-wide framework of potential inter-tidal habitat mitigation and compensation sites
The majority of defences in the North Solent are fronted and backed by European designations, such as Special Areas of Conservation (SACs) and Special Protection Areas (SPAs). Maintaining or improving these defences, must comply with European environmental legislation. Certain flood defence schemes have been delayed for over two years because replacement inter-tidal habitat could not be found to offset the projected coastal squeeze, resulting from the operational works.
As a result, the SDCP was initiated on behalf of the operating authorities within the North Solent region. The project covered the area between Hurst Spit, in Hampshire and PaghamHarbour, in West Sussex. The project verified mudflat and saltmarsh loss calculated by the Solent Coastal Habitat Management Plan (CHaMP, 2003) using a robust methodology of historical aerial photography interpretation (HPI) and analysis of topographic and tidal elevation data. It also estimated the area of coastal squeeze requiring compensation across the North Solent over the next 100 years assuming maintenance of all existing sea defences.
Potential habitat creation sites across the North Solent were identified using topographic and tidal elevation data. In order to assess the viability of the potential sites, local coastal managers were interviewed using a questionnaire based on Government economics and environmental criteria devised by the Environment Agency (EA), Natural England (NE) and the Channel Coastal Observatory (CCO). The questionnaire categorised the sites into preferred options for, hold the line, managed re-alignment or no active intervention (abandonment)* for time epochs 0-19, 20-49, 50-100 and 100 years or more, for consistency with SMP guidance. The area of designated freshwater habitat requiring replacement as a result of potential managed re-alignment was also identified.
The SDCP approach was innovative and has not been applied elsewhere in the U.K. The mixture of scientific data and input by local coastal managers has produced detailed guidance for inter-tidal habitat creation that will feed into the North Solent SMP. The set of rules applied to rank potential inter-tidal habitat creation sites into time epochs for potential re-alignment or abandonment was based on a suite of assumptions that are subject to change. The Isle of Wight Mitigation Study (which in addition to inter-tidal habitats, assessed other coastal Biodiversity Action Plan habitats), and the SDCP will inform second round SMP's from which findings will feed into the EA Southern Region's Regional Habitat Creation Programme (RHCP).
The work has been undertaken by the key statutory authorities. However, this study has not involved any decision making on the part of any statutory authority. The options suggested in this study are there to facilitate future debate and decision making as part of the SMP process. No landowners or wider stakeholders have been consulted as part of the project. These views will be sought as part of the SMP process. The SMP process will integrate all aspects of sustainable development, social, economic as well as environmental, prior to any final decisions on coastal management being made.
For further information please contact Dr Samantha Cope tel 023 8059 8469 email snc@noc.soton.ac.uk
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