Flood risk assessment

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A flood risk assessment (FRA) is an assessment of the risk of flooding from all flooding mechanisms, the identification of flood mitigation measures and should provide advice on actions to be taken before and during a flood. The sources of water which produce floods include: groundwater, surface water (rivers, streams or watercourses), artificial water (burst water mains, canals or reservoirs), sewers and drains, seawater.

For each of the sources of water, different hydraulic intensities occur. Floods can occur because of a combination of sources of flooding, such as high groundwater and an inadequate surface water drainage system. The topography, hydrogeology and physical attributes of the existing or proposed development need to be considered. A flood risk assessment should be an evaluation of the flood risk and the consequences and impact and vulnerability.^[1]

In the UK, the writing of professional flood risk assessments is undertaken by Civil Engineering Consultants. They will have membership of the Institution of Civil Engineers and are bound by their rules of professional conduct. A key requirement is to ensure such professional flood risk assessments are independent to all parties by carrying out their professional duties with complete objectivity and impartiality. Their professional advice should be supported by professional indemnity insurance for such specific professional advice ultimately held with a Lloyd's of London underwriter.

Professional flood risk assessments can cover single buildings or whole regions. They can part of a due-diligence process for existing householders or businesses, or can be required in England and Wales to provide independent evidence to a planning application on the flood risk.