Flood Map for Planning

Understand the Flood Map for Planning

 

Go to the Flood Map for Planning

Key to understanding the Flood Map for Planning

The map and associated information is intended for guidance, and cannot provide details for individual properties.

1. Floodplain

A floodplain is the area that would naturally be affected by flooding if a river rises above its banks, or high tides and stormy seas cause flooding in coastal areas. 

There are two different kinds of area shown on the Flood Map for Planning (rivers and the sea). They can be described as follows:

  • Flood Zone 3  shows the area that could be affected by flooding, either from rivers or the sea, if there were no flood defences. This area could be flooded:
    • from the sea by a flood that has a 0.5 per cent (1 in 200) or greater chance of happening each year;
    • or from a river by a flood that has a 1 per cent (1 in 100) or greater chance of happening each year.
  • Flood Zone 2  shows the additional extent of an extreme flood from rivers or the sea. These outlying areas are likely to be affected by a major flood, with up to a 0.1 per cent (1 in 1000) chance of occurring each year. 

These two colours show the extent of the natural floodplain if there were no flood defences or certain other manmade structures and channel improvements.

  • Where there is no blue shading, this shows the area where flooding from rivers and the sea is very unlikely. There is less than a 0.1 per cent (1 in 1000) chance of flooding occurring each year. The majority of England falls within this area. (For planning and development purposes, this is Flood Zone 1)

2. Flood Defences

Flood defences  shows flood defences built to protect against river floods with a 1per cent (1 in 100) chance of happening each year, or floods from the sea with a 0.5 per cent (1 in 200) chance of happening each year, together with some, but not all, older defences and defences which protect against smaller floods. Flood defences that are not yet shown, and the areas that benefit from them, will be gradually added.
 
Areas benefiting from flood defences  are areas that benefit from the flood defences shown, in the event of a river flood with a 1 per cent (1 in 100) chance of happening each year, or a flood from the sea with a 0.5 per cent (1 in 200) chance of happening each year. If the defences were not there, these areas would be flooded.

Flood defences do not completely remove the chance of flooding, however, and can be overtopped or fail in extreme weather conditions. 
 
For information on flood defences which are not yet shown on the map, contact your local Environment Agency Office.

3. Main Rivers

The blue line Main rivers shows the main rivers, these are usually larger streams and rivers.

Our powers to carry out flood defence work apply to main rivers only. In England, DEFRA decides which are main rivers. The Welsh Government does this in Wales.

 

Flood map

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