Enviro + Geo Insight - GIS schema: Flooding

Areas Benefiting from Flood Defences

Layer name: Flooding-Areas_Benefiting_from_Flood_Defences_EA_NRW

This is a polygon based dataset that identifies areas that benefit from flood defences which offer protection against a 1 in 100 (1%) chance of flooding each year from rivers; or 1 in 200 (0.5 %) chance of flooding each year from the sea across England and Wales. This can include areas that would be protected by other defences for larger events e.g. 1 in 1000 (0.1%), but would only include areas protected against a 1 in 100 (1%) / 1 in 200 (0.5%) chance of occurring in any year. If the defences were not in place, these areas would flood in a 1 in 100 (1%)/ 1 in 200 (0.5 %) or larger flooding incident. In mapping areas benefiting from defences, the EA/NRW assume that flood defences and other operating structures act perfectly and give the same level of protection as when their assessment of the area was made.

Geometry: Polygon

Coverage: England and Wales

Schema: 

Flood Defences

Layer name: Flooding-Flood_Defences_EA_NRW

This is a line based dataset that shows flood defences constructed across England and Wales which offer protection  equal to or better than 1 in 100 (1%) for rivers and 1 in 200 (0.5%) from the sea. 

Geometry: Line

Coverage: England and Wales

Schema: 

Flood Storage Areas

Layer name: Flooding-Flood_Storage_Areas_EA_NRW

This is a polygon based dataset that shows Flood Storage Areas across England and Wales that act as a balancing reservoir, storage basin or balancing pond. Their purpose is to attenuate an incoming flood peak to a flow level that can be accepted by the downstream channel. It may also delay the timing of a flood peak so that its volume is discharged over a longer time interval. The EA/NRW assume that flood storage areas act perfectly and give the same level of protection as when their assessment of the area was made.

Geometry: Polygon

Coverage: England and Wales

Schema: 

Flood Zone 2

Layer name: Flooding-Flood_Zone_2_EA_NRW

This is a polygon based dataset showing the best estimate the EA/NRW provide of the areas of land at risk of flooding, when the presence of flood defences are ignored and covers land between Zone 3 and the extent of the flooding from rivers or the sea with a 1 in 1000 (0.1%) chance of flooding each year. This dataset covers England and Wales, and is designed to support flood risk assessments in line with Planning Practice Guidance and should be used in conjunction with Flood Zone 3.

Geometry: Polygon

Coverage: England and Wales

Schema: 

Flood Zone 3

Layer name: Flooding-Flood_Zone_3_EA_NRW

This is a polygon based dataset showing the best estimate the EA/NRW provide of the areas of land at risk of flooding, when the presence of flood defences are ignored and covers land with a 1 in 100 (1%) or greater chance of flooding each year from Rivers or with a 1 in 200 (0.5%) or greater chance of flooding each year from the Sea. This dataset covers England and Wales, and is designed to support flood risk assessments in line with Planning Practice Guidance and should be used in conjunction with Flood Zone 2.

Geometry: Polygon

Coverage: England and Wales

Schema: 

Historical Flood Events

Layer name: Flooding-Historical_Flood_Events_EA_NRW

This dataset includes polygonised features that correspond to records the maximum extent of historic flooding from rivers, the sea, groundwater and surface water. Records began in 1946 when predecessor bodies started collecting detailed information about flooding incidents, although limited details may be included on flooding incidents prior to this date. If an area is not covered by the Historic Flood Events dataset it does not mean that the area has never flooded, only that the Environment Agency/Natural Resources Wales do not currently have records of flooding in this area that meet the criteria for inclusion. It is also possible that the pattern of flooding in this area has changed and that this area would now flood or not flood under different circumstances. Outlines that don’t meet this criteria are stored in the Recorded Flood Outlines dataset. Takes into account the presence of defences, structures, and other infrastructure where they existed at the time of flooding, and includes flood extents that may have been affected by overtopping, breaches or blockages. Flooding is shown to the land and does not necessarily indicate that properties were flooded internally. This dataset covers England and Wales.

Geometry: Polygon

Coverage: England and Wales

Schema: 

Risk of Flooding from Rivers and the Sea (RoFRaS)

Layer name: Flooding-Risk_of_Flooding_from_Rivers_and_the_Sea_EA_NRW

This is a national assessment of flood risk for England and Wales produced using local expertise. The dataset shows the chance of flooding from rivers and/or the sea, based on cells (polygons) of 50m squared. Each cell is allocated one of four flood risk categories, taking into account flood defences and their condition: 

• Very low (less than 1 in 1000 chance)
• Low (less than 1 in 100 but greater than or equal to 1 in 1000 chance)
• Medium (less than 1 in 30 but greater than or equal to 1 in 100 chance)
• High (greater than or equal to 1 in 30 chance)

Geometry: Polygon

Coverage: England and Wales

Schema: