After port construction at Lappel Bank in the Medway Estuary and at Fagbury Flats in the Orwell Estuary, 86 hectares of wetland were lost. In 1997 the British government ordered for these losses to be compensated. The Department for Environment Food and Rural Affairs (DEFRA) was in charge of this process.
Planning and design
After three years of studying, Wallasea was chosen in 2004 as the location for the creation of compensating wetlands. For various reasons: this island was chosen as the best suitable for Management Realignment, the area was large enough to compensate the wetlands lost, dredged material from maintenance dredging of a nearby port could be used, the existing sea walls were in need of improvement and studies showed that the construction itself would not damage the surrounding area or adversely impact present bird and wildlife populations.
The design was fine-tuned by Associated British Ports (APBmer), after a design by Defra, with help of numerical modelling and a study of the existing wild life. Aim of the design was also to minimize the impact on the estuary. Local authorities joined in the designing phase.
The design includes three separate areas with no water exchange between them, other than via the main estuary. Therefore, each of them could be given its own identity. Dredged materials were used to create salt marshes and to construct a new embankment inland from the old one. Attract rare lagoon habitants into the saline lagoon was part of the design.
The new wetland area will function as flood protection. The mudflats and marshlands will reduce the tidal wave energy and thus, will shape a natural flood defense.
Next to the environmental and safety issues, the design also meets a number of socio-economic goals, such as eco-tourism and fisheries. A four kilometers footpath will attract people, as will the beach. Because, most tourism is concentrated in summer, this will not interfere with the nesting season of the birds.
The total size of the new wetlands is twice as large as the required size to compensate for lost values. Moreover, the design includes multiple features to enhance the biodiversity within the wetlands.
Building with Nature?
The wetlands at Wallasea serve various infrastructural purposes (flood protection, recreation, wetland habitat) and create additional environmental value. The size of the new wetland does not only compensate for the areas lost during port construction, but is larger than required. Also, the integral design that includes environmental, social and economical is a good example of EDD.