Flood hazard mapping is an exercise to define those coastal areas which are at risk of flooding under extreme conditions. As such, its primary objective is to reduce the impact of coastal flooding. However, mapping of erosion risk areas may serve to achieve erosion risk reduction. It acts as an information system to enhance our understanding and awareness of coastal risk.
Based on kindly provided information by the ClimateTechWiki and the TNA Guidebook on 'Technologies for Climate Change Adaptation' by Matthew M. Linham & Robert J. Nicholls
General Description
Flood Hazard Mapping are easily-read, rapidly-accessible charts and maps which facilitate the identification of areas at risk of flooding and also helps prioritise mitigation and response efforts (Bapulu & Sinha, 2005).
Flood hazard maps are also designed to increase awareness of the likelihood of flooding among the public, local authorities and other organizations and encourage people at risk to learn of the options and take appropriate action (Environment Agency, 2010).
It is important to consider the changes over time in flood hazard mapping. For example, SLR and changes in storm intensity, occurring as a result of climate change, will causes changes in the areas susceptible to flooding.
Advantages
Identification of flood risk areas is likely to help in the planning of a more effective emergency response. Flood hazard mapping will allow quantification of what is at risk of being flooded such as the number of houses or businesses. This will help identify the scale of emergency and clean-up operations.
For example, the creation of flood hazard maps will allow planners to locate essential infrastructure, such as electricity supplies, sewage treatment, etc., and emergency services so that they can continue to serve during an extreme event. Alternatively, flood hazard mapping may highlight a requirement to defend these elements from flooding.
The creation of flood hazard maps should promote greater awareness of the risk of flooding. This can be beneficial in encouraging hazard zone residents to prepare for the occurrence of flooding. In the longer-term, flood hazard maps can support planning and development by identifying high risk locations and steering development away from these areas. In order for this to occur, the consideration of flood hazard maps must be integrated into planning procedures.
Disadvantages
In itself, flood hazard mapping does not cause a reduction in flood risk, It must be integrated into other procedures, such as emergency response planning and town planning, before the full benefits can be realised.
More advanced, accurate flood hazard maps are likely to rely on complex numerical models due to the lack of observed extreme event data. This requires a degree of expertise to implement. The collection of topographic and bathymetric data to complement extreme water level and wave height information could also be expensive to collect.
Costs
The costs of flood hazard mapping are not widely known. Therefore it is not possible to provide likely cost estimates here. However, a number of factors which are likely to contribute toward the cost of flood hazard mapping:
- External expertise on numerical modelling of flood risk brought in from academic institutions or commercial organisations
- Topographic surveys (LiDAR or remote sensing) to provide information on land elevation which will feed back into the flood risk model
- Historic costs of collecting extreme event data such as water levels, wave heights, etc.
- Cost of employing a Geographic Information System (GIS)
Barriers to implementation
Flood hazard mapping relies on the availability of topographic, and long-term extreme event data and complex numerical modelling techniques.
A lack of public understanding about the benefits of flood hazard mapping may also provide a barrier to implementation. If the public is unaware of the benefits of flood hazard mapping, they may prefer to see public money spent on more tangible flood and erosion protection measures.
Opportunities for implementation
Flood hazard mapping complements and strengthens other adaptation options, such as flood-proofing measures, emergency planning, provision of flood shelters and evacuation planning. As such, this approach could be applied almost universally, irrespective of the other adaptation technologies that are used.