Managed Realignment: An economic appraisal of the Humber catchment

European coasts are coming under increasing threat as a result of climate change from erosion and flooding, with 20% of the coastline seriously impacted and 15km² of land lost each year (Doody et al. 2004). While coastal defences such as sea walls have been constructed since Roman times to protect human settlements from the sea, it is now increasingly recognised that these defences are unsustainable. The security provided by the 'hard' engineered defences has encouraged excessive development on the coast, and the defences themselves have led to the loss of intertidal habitat and the natural protection it provides. An alternative to maintaining the 'hard' defences (hold-the-line) to protect the land from increasing sea levels is managed realignment, where the engineered defences are deliberately breached. By allowing the coastline to recede to a new line of defence further inland, intertidal habitat is created providing natural protection from flooding and erosion. In the face of rising sea levels, the existing coastal management strategies being reviewed, it is pertinent to assess the economic efficiency of all methods of coastal defence. In this study, a cost-benefit analysis is undertaken in the Humber catchment of North-east England, comparing the holding-the-line and managed realignment.