You may be able to find Ordnance Datum information from the Ordnance Survey. Site levels need to be stated in relation to the Ordnance Datum (the height above average sea level). You may also need to show your site in relation to its surroundings - contact your local planning authority to check if you need to do this. a cross-section of the site showing finished floor or road levels and any other levels that inform the flood risk, for example existing raised banks and flood defence walls.the existing site levels and the levels of your proposed development.any structures that could affect water flow, for example bridges, embankments.You also need to provide a site plan showing: You can buy a location plan from the Ordnance Survey. other geographical features, for example railway lines or local landmarks such as schools or churches.any rivers, streams, ponds, wetlands or other bodies of water.You need to provide a location plan showing: essential infrastructure in flood zone 3a or 3b.

You’ll need to carry out an exception test if your development is: The exception test shows how you’ll manage flood risk on and off the site. If the sequential test shows there are not suitable alternative sites, you may need to carry out an exception test. You need to carry out a sequential test if one has not already been done for the type of development you plan for your proposed site - check with your local planning authority. A sequential test compares your proposed site with other available sites to show which one has the lowest flood risk. Check if you need to do a sequential testīefore you start a flood risk assessment, check if you need to carry out a sequential test. Refer to the strategic flood risk assessment in your own flood risk assessment.Ĭheck if your development is within 20 metres (m) of a main river.Īsk the Environment Agency for advice if it is. your lead local flood authority - contact your local council to find out who this isĬontact your local planning authority or check the planning section of their website for their strategic flood risk assessment if one has been adopted as part of the local plan.Research your development siteĬontact the following organisations for information about flood risk in your area: Check with your local planning authority if they have any specific software requirements, for example for producing detailed hydraulic models.

Your written flood risk assessment can be in any format but must include the relevant plans, surveys and assessments. Read flood risk assessment for planning applications if you’re not sure if this guidance applies to you.

Flat earth after flood map