How the Flood Map for Planning Affects Development
The Flood Map for Planning is a screening tool that determines whether development proposals require a Flood Risk Assessment, dividing land into three flood zone categories.
What Is the Flood Map for Planning and Why Does It Matter?
The Flood Map for Planning serves as “a screening tool produced by the Environment Agency to help determine whether development proposals will require a Flood Risk Assessment” as part of planning submissions. It provides an initial indication of risk rather than definitive conclusions.
Flood Zone Classifications
The system divides English land into three categories:
- Flood Zone 1: Less than 1 in 1,000 annual probability of river or sea flooding (<0.1%) — considered low risk
- Flood Zone 2: Between 1 in 100 and 1 in 1,000 annual probability of river flooding, or 1 in 200 to 1 in 1,000 for sea flooding — considered medium risk
- Flood Zone 3: 1 in 100 or greater annual probability of river flooding, or 1 in 200 or greater for sea flooding — considered high risk
Zone 3 subdivides into 3a and 3b, with 3b designating the functional floodplain.
Development Impact
Site size and zoning determine whether developers must prepare flood risk assessments, exception tests, and sequential tests. Even Zone 1 designations may require further investigation if unmapped watercourses exist nearby.
“Flood Zones are often based on strategic scale information,” sometimes appearing inaccurate. Where the Flood Map for Planning does not accurately reflect site-specific conditions, detailed modelling can be used to refine the flood zone boundaries and support planning applications.