European Approaches to Managed Realignment
This research project has been conducted by a consortium comprising Halcrow, the Centre for Social and Economic Research on the Global Environment at the University of East Anglia and Cambridge University's Cambridge Coastal Research Unit to identify the constraints and incentives to Managed Realignment of flood defences, both on rivers and on the coast.
Managed realignment means the deliberate process of realigning river, estuary and/or coastal defences. This may take the form of retreating to higher ground, constructing a set-back line of defence, shortening the overall defence length to be maintained, reducing wall or embankment heights or widening a river flood plain. The purpose of managed realignment schemes might be to:
- Reduce defence costs by shortening the overall length of defences to be maintained;
- Increase the efficiency and long term sustainability of flood and coastal defences by recreating river, estuary or coastal habitats and using their flood and storm buffering capacity;
- Provide other environmental benefits through re-creation of natural habitats; or
- Provide replacement habitats in or adjacent to a European designated site to compensate for habitat loss as a result of reclamation or coastal squeeze.
Whilst Managed Realignment has been a topical issue for many years now, there have been few examples of the practice being implemented. There is an urgent need for a better understanding of issues associated with Managed Realignment (Wolters et al. (2005)), and how it could be better delivered through future flood defence planning. This research project sets out to answer the following six questions:
- Where has Managed Realignment been tried?
- What are the drivers (incentives) for Managed Realignment?
- What are the constraints (obstacles) to Managed Realignment?
- What can we learn from experience of Managed Realignment?
- What are the costs and benefits of Managed Realignment?
- How can we realise the benefits of Managed Realignment?
The contribution from the Coastal Research Unit (Dr I Möller) to this project comprises a review of experience of Managed Realignment (MR) overseas; conducting postal questionnaires and gathering information and opinions from key players in the academic, political, and nature conservation areas in the Netherlands, Germany, and Denmark. The review focuses in particular on an examination of the implementation of present policy relating to Shoreline Management Planning, economic valuation, financial compensation, nature conservation and planning. The results of this work show that, in the countries reviewed as part of this project, MR has been implemented mainly as part of nature conservation or (re-)creation projects in estuarine locations in the Netherlands (e.g. Fiesland, the Scheldt Estuary), and Germany (e.g. the Elbe river). As is the case in the UK, open coast sites are rare. Furthermore, the most prominent driver behind MR in those countries consulted was that of lower defence costs. Improved flood and coastal protection and habitat creation were also regarded as important. Improvements in water quality were generally regarded as least important.
With respect to the constraints to MR, the problem of political acceptability appears to be the most important factor (identified by individuals of all countries) limiting the implementation of MR as a coastal management strategy. Most respondents regarded issues of direct cost and legal constraints as moderately important and no clear general picture emerged with regard to issues of technical feasibility or compensation.
The above analysis does indicate some interesting differences, however, with respect to the particular countries concerned (see Figure 1 (a) and (b) for a graphical representation of these country-by-country questionnaire results of drivers and constraints to MR respectively).
Figure 1 (a): Comparison of level of importance awarded to different MR 'drivers' by questionnaire respondents from different countries (NB: if more than one respondent from one country, means of the levels indicated were used; the number of respondents per country is listed in section 3.2.1) (Level of importance: 1 = 'high', 2 = 'moderate', 3 = 'low', 4 = 'no opinion')
Figure 1 (b): Comparison of level of importance awarded to different MR 'constraints' by questionnaire respondents from different countries (NB: if more than one respondent from one country, means were used; the number of respondents per country is listed in section 3.2.1) (Level of importance: 1 = 'high', 2 = 'moderate', 3 = 'low', 4 = 'no opinion')
- Wolters, M., Bakker, J.P., Bertness, M.D., Jefferies, L., and Möller, I. (2005) Saltmarsh erosion and restoration in south-east England: squeezing the evidence requires realignment. Journal of Applied Ecology, 42, 844-851.
- Möller, I., Garbutt, A. and Wolters, M. 2001 Managed realignment of sea defences and the re-creation of saltmarshes in south-east England. In: Green, R.E. et al. (eds). Impacts of climate change on wildlife.
- A project report can be found at:
The project was carried out in collaboration with Halcrow Group Ltd and the University of East Anglia.