Coastal Management Decision Making
Coastal management plans are typically supported by decision-making tools, that are intended to focus physical monitoring or economic information into guiding a decision. However, these tools can be much like looking through a magnifying glass - while providing focus, they can simultaneously obscure perception of other aspects of coastal behaviour. Therefore, rather than just copying a method because it has been used by someone else, or even because it's part of a policy, developing an understanding of decision-making tools should be part of their application. In many cases, choosing the decision-making tool will have more influence than the information being used to develop the decision.
In order to achieve a useful plan, it is necessary that relationships between information, decision-making, site characteristics, costs and uncertainty be recognised. For example, application of a simple decision-making framework usually requires only a small amount of information and comes at a low cost. However, it will inherently contain higher uncertainty, which is increased in areas of complex geomorphology. The relative degree of stakeholder and community involvement in valuing assets and determining adaptation pathways is a major factor influencing the complexity of decision-making.
Coastal Monitoring
Coastal monitoring is a fundamental tool for informed decision-making in coastal management. Monitoring is therefore a function of the issues faced by a coastal manager, and their opportunities for action. Coastal monitoring objectives may be associated with broad levels of coastal management, with increased resources required for both monitoring and management at higher levels.
Management Level | Description | Monitoring Objectives |
0.     Reactive | Coastal management addressed as required after disturbance event | Confirm that reactive management remains feasible |
1.     Planned | Foreshore reserve used to provide buffer against coastal fluctuations | Allow forecast of effective time frame for buffer to be viable |
2.     Prioritising | Isolated management activities undertaken including storm clean-up, dune revegetation or armouring | Provide measure to assist decision-making |
3.     Adaptive * | Management activities deliberately varied according to conditions and width of foreshore reserve | Identify the need to change management effort |
4.     Active | Using sand management or structures to distribute erosive or accretive pressures | Quantify management actions |
* Note that adaptive management has a wider context here (i.e. includes shorter time frames) than adaptation to climate change
In most cases, state-changes indicating the need for adaptive decision-making should not be determined using the same set of coastal state indicators used to describe year-to-year coastal change. This is either because small progressive changes are obscured by more frequent fluctuations; or changes caused by extreme or anomalous conditions may be more clearly identified by the associated meteorological or oceanographic parameters, which can potentially be used to establish event likelihoods. Defining a separate set of long-term coastal state indicators is presently a topic of scientific research. However, improved capacity to use existing ‘short-term’ or ‘local’ coastal state indicators for identification of state-changes may be developed through greater spatial awareness or by modifying the derived analysis parameters.
An example of the influence of monitoring techniques to provide focus (or obscure) different aspects of coastal change is provided by how change to a beach position is measured:
Presentation of complete or partial beach profile volumes, or using a proxy such as vegetation line, may obscure or highlight the relative significance of cross-shore transport events, such as storm erosion and recovery. A key advantage of using vegetation lines is that relatively few erosion events create a ‘signal’, however, this may also restrict substantial change being identified if it is located within the beach flat itself.
Economic Tools
Many economic tools are used to support coastal management decisions, such as cost-benefit analysis, multi-criteria analysis, risk matrices, policy frameworks or vulnerability indices. However, individual applications can sometimes unbalance or obscure the decision. It pays to understand possible biases or limitations of a decision-making tool, and its assumptions, before use.
Cost-benefit analysis is apparently straightforward, but subject to wide manipulation. For example, two studies at the same location used CBA to demonstrate diametrically opposed cases for mangrove restoration or sea dyke construction. Differences were hidden in assumptions, including relative effectiveness of surge damping, land productivity compared to land sale value, design life assumptions, and distinction or aggregation of financial parties.
Convolution of cost-benefit analysis commonly occurs from selecting discrete scenarios for comparison, rather than examining a continuum of options. CBA is also plagued by ‘silver bullet’ thinking, where one form of management is required to address all issues, rather than using a strategic combination.
The opposite issue can occur when using multi-criteria assessment, particularly if simply ‘counting the ticks’ (i.e. without suitable weighting). A trivial example is if adaptability were given equal weighting to effectiveness in a flood defence scheme.Â
Inclusion of qualitative elements obscures economic approaches when near zero or near infinite values are applied. This is a frequent consequence of policy frameworks, where simple criteria are often used. Alternative management options can be discarded as ‘non-policy’ or have assumed effectiveness. For example, flood proofing does not change how often inundation reaches a threshold and is often excluded from the planning approvals process. In contrast, it is typically inherently assumed that evacuation plans provide adequate hazard mitigation for events above the threshold, although they only address human safety.
In some cases, decision-making tools can obscure the obvious, requiring unnecessary effort. A typical example is for discrete economic thresholds (e.g. a near-uniform coastal setback), a risk matrix is not needed to identify adaptation triggers. A more substantial example is large-scale application of coastal vulnerability indices, where only one or two parameters may be influential. For example, areas most susceptible to sea level rise are often low-lying, so use of a simple geo-indicator can substantially reduce analysis effort. Care must also be taken to ensure that vulnerability indices appropriately represent physical behaviour – an example being interactions between coastal slope and geology.