§ Lord Howie of Troon
asked Her Majesty's Government:
What is the definition of the concept of "managed retreat" in relation to coastal erosion; and to what kinds of coastline it is intended to apply. [HL2958]
§ The Minister of State, Ministry of Agriculture, Fisheries and Food (Baroness Hayman)
The term used by the Government is "managed realignment". As defined in the recent Project Appraisal Guidance, this is "the management of a process of establishing a new line of defence, often set back from the existing position, with the aim of improving the long-term sustainability of the defence, or contributing to other aims such as habitat creation". This would normally involve a deliberate breach of any existing defence so that inundation, or erosion, takes place up to a new line of defence, which may be natural or man-made.
It is necessary to recognise that the entire coastline of the UK has over centuries been subject to the natural process of erosion and deposition. This process may be increased by rising sea levels caused by climate change and long-term geological "tilt" which is increasing sea levels still further in the south and east of the country. The response cannot automatically be to build new and ever higher coastal defences to protect against flooding and erosion. Sustainability is a key criterion and the operating authorities need to consider a range of options, including "managed realignment" of the coastline.
The decisions on whether or not to continue defending a particular area will depend on a range of considerations, using benefit:cost analysis. Important factors will be the type of assets, both natural and man made, that are currently defended, and any loss or gain of important nature conservation habitat as a result of a decision to defend or not. Where no man-made defence currently exists, a decision whether or not to defend a particular area will be based on similar considerations.
Managed realignment needs to be considered as an option on all parts of the coastline. However, given the benefit:cost approach to decision making, such an approach is more likely where low value assets lie behind the existing defence which do not justify the investment necessary in maintaining or improving the existing defence.