Choosing and evaluating a management strategy

Overview

Sustainable coastal management and why coastal management always involves conflict between different groups.

What you need to know

Answer each one before you reveal it.

Questions from this subtopic

Each one with the model answer underneath.

1. 1

   What factors determine which coastal management strategy is chosen for a particular stretch of coast?

   Model answer

   The value and nature of the assets behind the coast, since a town or a railway justifies expenditure that farmland does not. The rate and type of the threat, whether slow cliff retreat, rapid erosion or tidal flooding. The physical setting: geology, wave energy, tidal range, sediment supply and drift direction. The position of the frontage within the sediment cell, and the consequences of any scheme for the coast updrift and downdrift. The money available and the source of it, and whether the maintenance can be sustained. Environmental designations and conservation obligations. The views of residents, landowners, businesses and interest groups. And the timescale being planned for, since a defence adequate now may not be adequate as sea level rises.

2. 2

   Why do most real coastal management schemes combine hard and soft engineering rather than using one or the other?

   Model answer

   Because different parts of the same frontage face different problems and have different values behind them, and because the two approaches compensate for each other's weaknesses. A town centre may need a sea wall because the shoreline cannot move, while the open coast either side of it is better served by nourishment and dune management. Even on a single frontage, a wall protects the land but destroys the beach in front of it, so nourishment is used to keep a beach that reduces the wave energy reaching the wall and extends its life; groynes are then used to hold the nourished material in place. A scheme built as a combination can also be phased, holding the line where the assets are and realigning where they are not, which is exactly what a shoreline plan for a whole cell sets out to do.

3. 3

   How would you judge whether a coastal management scheme has been successful?

   Model answer

   By asking several separate questions rather than one. Technically, has erosion or flooding actually been reduced on the frontage, measured against monitoring of beach profiles, cliff retreat rates and flood events, and has the structure performed as designed in storms? Economically, did the costs stay within estimate, do the benefits exceed them over the whole life of the scheme including maintenance, and is the maintenance being funded? Environmentally, what has happened to the beach in front, to habitats and designated sites, to the sediment cell as a whole, and to the coast downdrift? Socially, do residents feel safer, is property insurable, has access and amenity been maintained or lost, and were those affected consulted and compensated? And in terms of sustainability, will it still be working in fifty years under a higher sea level, or has it simply postponed the problem and enlarged the eventual bill?

4. 4

   Why can a coastal scheme be judged a success on one criterion and a failure on another?

   Model answer

   Because the criteria measure different things and are held by different people. A sea wall that has completely stopped erosion of the town behind it is a technical success, and the residents will say so, while the same wall has scoured away the beach, cut off the sediment feeding the coast downdrift and destroyed intertidal habitat, so on environmental and cell-wide criteria it is a failure. A managed realignment can be an ecological and financial success while being experienced as a betrayal by the farmer whose land was flooded. Evaluation therefore depends on the boundary drawn around the assessment, in space and in time, and on whose interests are counted, which is why the honest answer to whether a scheme worked usually has to specify for whom and over what period.

5. 5

   What does sustainable coastal management mean in practice?

   Model answer

   Managing the coast so that present needs for protection are met without passing on a larger problem, a larger bill or a degraded coast to the future. In practice that means planning at the scale of the whole sediment cell so that sediment supply is maintained and problems are not exported along the coast; preferring approaches that work with natural processes and can adjust as sea level rises over rigid structures that cannot; protecting and restoring natural defences such as beaches, dunes, marshes and reefs; accepting that some coast will and should retreat and planning for that in advance rather than defending everywhere; refusing new development in places that will not be defended in the long term; involving and compensating the people affected; and monitoring so that the plan can be revised as evidence and conditions change.

6. 6

   Why is doing nothing sometimes the most sustainable option?

   Model answer

   Because on a stretch of coast where little of value is at risk, defending it costs public money indefinitely, prevents the natural adjustment of the shoreline and, most importantly, stops an eroding cliff from supplying the sediment that feeds and protects beaches further along the cell. Allowing that erosion to continue keeps the sediment budget healthy, maintains habitats that can migrate landwards, and avoids committing future budgets to maintaining structures that will become steadily harder to hold as sea level rises. It is not the same as neglect: it is a deliberate policy, arrived at through appraisal and consultation, and it depends on planning controls preventing new building in the zone that is expected to be lost.

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