Wallasea Managed Realignment
Overview
DEFRA have recently completed a major coastal realignment project at Wallasea Island in the Crouch Estuary (Essex). This scheme will create a large expanse (108ha) of new mudflat and saltmarsh in compensation for habitats that were lost following port developments in the 1990s. Under commission to DEFRA, and the landowner (Wallasea Farms Ltd), ABPmer has provided input and advice on the site selection, scheme design, EIA and ecological monitoring aspects of this long-term project.
Environmental Impact Assessment and Numerical Modelling
For the EIA work, ABPmer initially produced a Scoping Study which was informed by discussions with Rochford District Council (RDC) and by the findings from an extensive public consultation exercise that was undertaken by DEFRA prior to the selection of the Wallasea site. The EIA was then completed on the basis of the agreed scope. The key issues addressed were: coastal processes, water/sediment quality, nature conservation and ecology, fisheries, marine heritage, coastal protection, navigation and the landscape and visual impacts. To inform the EIA, ABPmer also carried out a series of detailed numerical modelling studies to assess the short and long-term effects of the scheme on the hydrodynamic conditions (flow species, tidal conditions, etc.) and morphology (estuary shape) of the Crouch and Roach estuaries. This modelling was also used to refine the design of the realignment scheme itself.
3D scheme visualisation to inform consultation
As part of this proposal, ABPmer developed a computer-generated 3D visualisation of the scheme so that decision makers and stakeholders could 'see' how the project would look once completed. This takes the form of a theoretical 'fly-over' of the location (i.e. the site as if seen from a circulating helicopter) and includes a representation of the tidal movements in and out of the new habitat. It is hoped that this tool, which proved to be very useful communication device during the planning application, will be used for other such habitat creation proposals. Similarly, could be used to help authorities that are charged with coastal protection (EA and DEFRA) to describe how coastal flooding incidents might look in at-risk areas and thus help them convey to the public their rationale for coastal protection decisions.
Five-year ecological monitoring programme
Planning approval for this scheme was secured in February 2005 and the realignment took place in June/July 2006. ABPmer are currently undertaking ecological monitoring programme to verify the impacts predicted in the EIA and to assess the site's success in terms of delivering the compensation targets. This includes monitoring winter bird counts, benthic sampling, analyses of water flows; mapping of morphological changes and fixed-point photography work. We have also set up a dedicated web-site and overseen the installation of web cameras on site. It is hoped that the resulting internet presence will be used to inform ongoing stakeholder consultations for Essex Estuary Flood Management Strategies and also for generally conveying the messages and lessons of coastal realignment.
