According to Wikipedia, a flood risk assessment (FRA) is an evaluation of the risk of flooding from all possible flooding mechanisms, including the identification of appropriate flood mitigation measures and the provision of guidance on actions to be taken before and during a flood event. The sources of flooding include groundwater, surface water such as rivers and streams, artificial water sources such as burst water mains, canals, and reservoirs, as well as sewers, drains, and seawater.

For each source of water, different hydraulic intensities may occur. Flooding can result from a combination of sources, for example high groundwater levels combined with an inadequate surface water drainage system. The assessment must consider the topography, hydrogeology, and physical characteristics of the existing or proposed development. A flood risk assessment therefore involves evaluating flood risk together with the associated consequences, impacts, and vulnerability.