A Flood Risk Assessment is normally required for any planning application when the site of the proposed development is located within Flood Zones 2 or 3 according to the Environment Agency. However, we are often get asked by clients as to why the local Council/Environment Agency have asked for the Flood Risk Assessment when the proposed development is situated in Flood Zone 1.
Flood Zone 1 is an area with a lower than 0.1 percent chance of flooding. Flood Zone 1 sites with a minimum of 1 hectare are required to undergo a Flood Risk Assessment. There are also sites which are smaller than 1 hectare in Flood Zone 1 which need a Flood Risk Assessment, including sites which have serious drainage issues that have been notified to the local planning authority by the Environment Agency. Critical Drainage Areas (CDA) are particular areas in Flood Zone 1 where man made drainage infrastructure has been recognized as having a high risk of failing, which could result in runoff causing problems downstream. A Flood Risk Assessment does not have to be only an area in which flooding issues could occur.
Flood Zone 1 may also require a Flood Risk Assessment. This is required if your project might be affected by flooding from other sources (surface reservoirs or water drains) or a shift in development’s use to a class that is more vulnerable like commercial or residential.
What happens if my site is situated within the Flood Zone 2?
A Flood Risk Assessment that is specifically designed for sites in Flood Zone 1 won’t be appropriate for sites within Flood Zone 2 or 3. Flood model data from Environment Agency and Council will be required if the Site is located within an area with a higher risk of flooding. Even if a portion of the Site redline planning boundary falls within Flood Zone 2 or 3 or if the development is located within the lower flood zone (Flood Zone 1), it will be considered to be in Flood Zone 1.
How can I find out which Flood Zone my Site is in?
Your site will fall into Flood Zone 1 to 3 if it is located in England. The Flood Zone was established by the Environment Agency Flood map. Find out which Flood Zone your site is located in, enter your postcode on the Environment Agency Flood Map to determine.
Natural Resources Wales (NRW) has its own Flood Zones when your site is situated in Wales. The maps display three development advisory zones (A-B C and A), which can be attributed to different plans. Zones B and A are generally areas with low risk. Zone C is the highest flood line and is further subdivided into C1 and C2.
Zone C1 is an area of floodplains that have been created and served by important infrastructure, like flood defences.
Zone C2 can be described as an “area of floodplain that is not surrounded by significant flood defence infrastructure.”
In essence If the Site is in a Flood Zone C1 or C2 it is the equivalent of the EA’s Flood Zone 3.
If your site is located located in Scotland and you are in Scotland, the Scottish Environmental Protection Agency (SEPA) assess flood risk based on the likelihood of flooding due to Rivers, Surface Water and Coastal Flooding. These are divided into high, medium and low risk zones.
Where can I purchase a Flood Risk Assessment?
We are able to provide the Flood Risk Assessment, suitable for Sites in a Flood Zone 1. The assessment considers flooding from all sources with a concise report of flood hazards which may be present.
