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JBA Flood Data v's EA Flood Data
We are often asked why there is a difference between the 2 sets of data. Please find below a table of the differences.
Introduction
In the UK, both JBA Risk Management and the Environment Agency (EA) provide flood mapping services, but they differ in scope, resolution, and application.
Environment Agency (EA) Flood Mapping:
- Purpose: The EA's flood maps are designed to inform the public and support planning decisions by illustrating areas at risk of flooding from rivers, the sea, and surface water.
- Resolution: These maps are typically produced at a national scale, offering a broad overview of flood risk areas.
- Accessibility: EA flood maps are publicly accessible and serve as a general guide for understanding flood risks across England.
JBA Risk Management Flood Mapping:
- Purpose: JBA specializes in high-resolution flood mapping for detailed risk assessment, catering to insurers, financial institutions, and other stakeholders requiring precise flood risk data.
- Resolution: JBA provides flood maps at a 5-meter resolution for the UK, enabling detailed analysis at the individual property level.
- Scope: Their maps cover various flood types, including river, surface water, coastal, groundwater, dam break, and canal failure, offering a comprehensive view of flood hazards.
- Application: JBA's data supports activities such as insurance underwriting, risk management, and strategic planning, where detailed flood risk information is crucial.
In summary, while the EA provides broad, publicly accessible flood risk maps for general awareness and planning, JBA offers high-resolution, detailed flood mapping tailored for specialized applications requiring precise risk assessments.
A table below shows some comparisons side by side.
| Hydraulic model component | JBA Flood maps | EA mapping |
| Coverage | UK: England, Scotland, Wales, Northern Ireland and Crown Dependencies (Channel Islands and Isle of Man) | England |
| Updates | Rolling annual updates incorporating best available height data | Irregular, no defined programme |
| Modelling and display resolution | 5m | Variable |
| Flood types | Flood extents and water depths (separated by flood type and return period)
|
Flood extents only
|
| Defence data | River defended areas Surface water defended areas Attribution: Standard of Protection, defence type, confidence level | Limited Areas Benefitting from Defence data(showing areas protected to 100 year) |
| Additional Data (extents only) | Groundwater chalk (75, 100 and 200 year) Dam break, Canal breach, Internal Drainage Boards | EA Long Term Flood Risk Data(low, med & high risk taking into account defences)Flood Risk from Reservoirs |
| Additional derived data / Services | Property and Postcode level data Flood hazard scores & Floodability Unflood Pricing Data Climate Change Analytics data | Flood Risk for Planning(Planning Zones 1-3) |
| DEM Type | Bare earth DTM (Lidar, Photogrammetry, Contour Derived, RADAR) | Lidar, RADAR |
| Hydrology, Runoff and loss assumptions / urban drainage assumptions | Generalised modelling approaches applied consistently over the whole of UK based upon local spatially varying data. | EA data contains some detailed local study data. |
The 2 datasets have multiple differences in both the data that they use and assumptions that feed into the modelling.
In conclusion..
• JBA provide separate flood layers for river, surface and coastal. The EA combine river and coastal into a single layer.
• JBA provide more return periods, compared to the EA.
• JBA data is updated annually, the update schedule for EA is unknown.
• JBA provide flood depth information for all flood types. EA provide extent information for river/coastal.
• The JBA modelling resolution is 5m nationally. The EA resolutions vary.
• JBA spend a significant amount of time editing the terrain data further for structures that may impede flow.
• JBA modelling is undefended, and we create an additional defended area layer using information from a range of third parties.