Professional guidance can take a number of forms, ranging from informal advice to a full site specific Flood Risk Assessment (FRA).The required level of consultation will depend largely on the vulnerability of the project or development, the anticipated flood hazard level and the level of FRA required (if any) by local legislation.
Firstly, informal advice can represent a useful and effective means to gain a greater understanding of flood hazard. Professional forums and even professional social-media platforms can provide a means to access professionals with expertise in the field of flood risk assessment. Academics, with expertise in your location of interest, may also prove a useful resource. They may have an intricate knowledge of flood hazard, as well as being able to identify key datasets in the region.
A more detailed understanding of flood risk can be obtained via a flood risk appraisal. A flood risk appraisal differs from a site specific FRA, in that it provides a more localised view of flood risk (than provided by the Think Hazard tool), but still a broad view of flood risk. These studies are typically desk studies that will attempt to provide a generic assessment of flood risk by pooling together available information, and perhaps undertaking some coarse scale modelling. A flood risk appraisal will highlight key areas where a more detailed study may be required. Flood risk appraisals should be undertaken by consultants who have specific expertise in undertaking and delivering flood risk assessments. Preferable, the consultant will also have local expertise, and consequently be familiar with available data and information as well as relevant local legislation.
A site specific FRA represents the most detailed appraisal of flood risk at a given location. FRA’s will typically include engineering level site assessments, perhaps including detailed flood modelling. FRA’s can provide detailed information about flood risk, and inform the design process as to the appropriate level of flood defences or site adaptation required. FRA’s can be expensive, and should be undertaken by consultants with expertise in site specific flood risk assessments. The consultant should also have extensive experience undertaking FRA’s under the given climatology, topography, as well as being familiar with local legislation. If the project involves construction, there may be relevant building standards that apply to the project regarding flood risk, e.g. drainage for highways and embankment stability. They will need to have appropriate skills in hydrology, hydraulics and computational river modelling. Always ask for detailed examples of relevant experience from any consultant you wish to hire for these purposes.
The level of professional guidance will depend largely on the vulnerability of the project or development and the identified hazard level. High vulnerability assets are assets that would be acutely impacted should they become inundated. For example, the Planning and Policy Statement 25 (PPS 25) in the UK, provides a classification of flood risk vulnerabilities that may be useful in determining the vulnerability of a project. PPS 25 defines partitions vulnerability into 5 categories:
Essential Infrastructure - all infrastructure that cannot be relocated, regardless of hazard level.
Highly vulnerable - assets that would acutely exacerbate the impacts of a flood, should they become inundated. Examples include emergency response units, hospitals, power stations, installations of hazardous materials.
More vulnerable - assets that would result in significant damage should they become inundated. Examples include residential buildings, educational and landfill facilities.
Less vulnerable - assets that would not significantly exacerbate the impacts of a flood, but would result in damages. Examples include shops, cafes, non-residential establishments, waste treatment (non-hazardous), agricultural buildings and land.
Water compatible - infrastructure that does not result in damages, during a flood. Examples include flood defences, amenity open space, sports and recreational ground, docks and marinas.
A Highly Vulnerable asset, such as a hospital, will require a detailed understanding of flood risk. Therefore, for all hazard intensities greater than Very Low, a site specific FRA would be highly recommended.
- For all assets potentially vulnerable to flooding, consider commissioning a site specific FRA, with the aim being to provide a detailed understanding of local flood risk.