- Update frequency
quarterly
- Lineage
- In 2010 the Environment Agency published the National Reservoir Inundation Maps. The maps provide an indication of the flooding that would occur if a failure of a reservoir embankment or structure led to an uncontrolled release of water. The Environment Agency has reviewed, updated and improved the reservoir flood maps as part of the Reservoir Flood Mapping Project. The maps show the extent of flooding for all large-raised reservoirs that were in operation in October 2016. New reservoirs after that date will be modelled under the next review of the flood maps, which is due in by 2025.
Reservoir Flood Extents - Wet Day (National)
Summary
This data shows the individual flood extents for all large raised reservoirs in the event that they were to fail and release the water held on a “wet day” when local rivers had already overflowed their banks.
It represents a prediction of a credible worst case scenario, however it’s unlikely that any actual flood would be this large. The data gives no indication of likelihood or probability of reservoir flooding.
Flood extents are not included for smaller reservoirs or for reservoirs commissioned after the reservoir modelling programme began in October 2016.
Categories
Use limitation statement
There are no public access constraints to this data. Use of this data is subject to the licence identified.
Licence
Open Government LicenceAttribution statement
© Environment Agency copyright and/or database right 2025. All rights reserved.
Coordinate reference system
http://www.opengis.net/def/crs/EPSG/0/27700Geographic extent
- Latitude from: 49.943 to 55.816
- Longitude from: -6.236 to 2.072
Language
English
Metadata identifier
d81646cf-37e5-4e71-bbcf-b7d5b9ca3a1c
Data and Supporting Information
| Data services and download by area of interest | Link | Action |
|---|---|---|
| Download data by area of interest and format | N/A | Open link |
| Reservoir Flood Extents - Wet Day WMS | Copy link | Preview |
| Reservoir Flood Extents - Wet Day WFS | Copy link | N/A |
| OGC API - Features service | Copy link | Open link |
| Full downloads and supporting documentation | Format | Action |
|---|---|---|
| Data Version.txt | TXT | Download |
| Reservoir_Flood_Extents_Wet_Day.lyr | LYR | Download |
| Reservoir_Flood_Extents_Wet_Day_National.gdb.zip | ZIP | Download |
| Reservoir_Flood_Extents_Wet_Day_National.geojson.zip | ZIP | Download |
| Reservoir_Flood_Maps_Data_Guide.pdf | Download |