Coastal erosion

What is coastal erosion and when is it a problem?
What can be done?
Key concepts
Indicators and monitoring
Potential interventions
Setback lines
Use of models
EU policies and Directives
The way forward
How to do it?
Systematic approach
Decision loop
Relevant Web links


3. Action needed: yes / no ?
Make your problem and objectives
Measurable: You should be able to measure the extend of the problem and whether you are meeting the objectives or not
Achievable - Are the objectives you set, achievable and attainable?
Realistic – Can you realistically achieve the objectives with the resources you have?
Time – When do you want to achieve the set objecti

Once an erosion problem has been specified (step 1) and quantified (step 2) in terms of one or more indicators, a clear decision recipe may help in deciding whether action is needed or not. First part of this recipe is a benchmarking procedure, answering several questions:

  1. What is the actual state of the indicator ?
  2. What is the desired state, or threshold value of the indicator ?
  3. Is the desired state achievable and attainable ?
  4. Who is concerned ? Who is responsible ?

1. What is the actual state of the indicator ?

Monitoring of beaches and the near shore zone provides important information about the state of the coastal system, more in particular about the actual state of the indicators of our interest. It represents input into the statistical descriptors and numerical models.

Key points for any monitoring program include:

  • Establish what the data is to be used for. Select specific indicators. A wide range of data could be used in coastal management, including data on winds, waves, tides, beach sediment, offshore bathymetry, coastal profiles, geomorphologic features, coastal defences, beach nourishment or recycling. All will cost money to collect and that cost should be justified;
  • Establish a reliable system of ground control points or permanent markers that are used by all surveying groups, whatever technique they are using;
  • Explicitly state the datum system to be used;
  • Establish a clear set of guidelines for the surveys, including tolerances and National or International Standards to be met (such as ISO or British Standards) and guidance on when to survey (with respect to the months, the spring-neap tidal cycle and the occurrence of storms).

An assessment of data needs for specific coastal state indicators is given in CONSCIENCE report D10.; an overview of innovative monitoring methods in CONSCIENCE report D15 and an update of available models in CONSCIENCE report 13b and 13c

2. Desired state or threshold value

The definition of a desired state or threshold value of an indicator, is necessary to enable a clear signal for action: whenever the actual state of an indicator shows a negative difference from the desired state, action is due.
Examples of different thresholds and benchmarking procedures may be found e.g. in CONSCIENCE report D8, and in the pilot site reports Holland, Pevensey, Costa Brava

Favourable sediment status
Basically, the thresholds for different indicators all relate to a favourable sediment status (key concept of shore line erosion mangement) of a specific sub-cell of the coastal system. A fine example of which is provided by the pilot site Holland.


3. Achievable and attainable ?

Time scale
Do we have time to react, or is immediate action the only option ? The time scale (see step 2) involved, is an important aspect considering achievability of the objective to maintain a certain desired state of an indicator.

Strategic sediment reservoir
Do we have the resources to tackle the problem ? According to the EUROSION recommendations, advocating sediment management as a key to coastal erosion management, one of the key concepts is a strategic sediment reservoir:

supplies of sediment of ‘appropriate’ characteristics that are available for replenishment of the coastal zone, either temporarily (to compensate for losses due to extreme storms) or in the long term (at least 100 years). They can be identified offshore, in the coastal zone (both above and below low water) and in the hinterland.

The definition of strategic sediment reservoirs must guarantee sediment resources.

Financial resources
Besides the physical resources, financial resoources are crucial to achieve the objectives.


4. Who is concerned ? Who is responsible ?

Decision proces
The choice for an achievable desired state (or acceptable threshold value), typically is a political one. It is closely linked to the availability of resources and to the question who has access to it.
As illustrated for example by the various CONSCIENCE pilot sites and by CONSCIENCE report D8, responsibilities and decision making processes on coastal erosion management, show large differences across Europe. A clear analysis of this process at a particular site is necessary to attain an implementable strategy.


A specific targeted research project under the
EU’s 6th Framework Programme for Research (FP6)