New Groundwater Flood Risk Tools for Public Bodies
Making Groundwater visible: new data and a new offer for Lead Local Flood Authorities and public service organisations
Groundwater flooding is one of the hardest flood sources to screen for. National flood zone mapping is built around rivers, the sea and, since NaFRA2, surface water. It does not include groundwater, and the Environment Agency’s latest national flood and coastal erosion risk management report gave no estimate of the scale of the risk because “there are too many gaps in our understanding and evidence of groundwater flood risk”.
Lead Local Flood Authorities (LLFAs) are left to deal with groundwater in strategic flood risk assessments, planning consultations and flood investigations without a consistent national starting point.
Our offer
To support public bodies in publishing data and making their findings freely available to the public on a non-commercial basis, we have created a simple, high-level screening version of our latest map, the Groundwater Flood Risk Screening Map of Great Britain (GW200), so that LLFAs and other public service organisations can share groundwater flood risk information with the public without charge.
GW200 covers Great Britain on a 200 m grid and flags where groundwater flood risk needs more detailed attention. It is free for non-commercial use and can go on your website and in your public documents.
We are offering it alongside our high-resolution GW5 and FloodSmart Analytics Groundwater (FSAGW) flood risk maps, which are available to each LLFA and other public body at 50% off our standard prices. Each council and LLFA is a separate end user and takes its own licence, which also covers use on its behalf by its contractors, consultants and other agents acting under its control. GW200 is for public service organisations to share with the public.
- GW200 is the layer you can publish. It is free for non-commercial use.
- GW5 and FSAGW are the working layers behind it. GW5 maps subsurface groundwater risk and FSAGW maps surface groundwater risk. They provide the highest resolution, most complete groundwater flood risk data nationwide, on a 5 m grid, for in-house use.
This means authorities can take advantage of the most accurate and detailed groundwater data available, and also publish reports and decisions supported by reduced-resolution evidence at 200 m scale for wider public access. You do not have to buy anything to use GW200. You can take it on its own, but we recommend that authorities also license GW5 and FSAGW, so they have the full detail behind the screening map. A site can be exposed to subsurface risk without surface risk, and the other way round, so the two detailed datasets are designed to be used together (see Groundwater Flood Risk: Completing the Picture).
We also make the data available through a platform that puts the NaFRA surface water, rivers and coastal data alongside it, for more detailed analysis by LLFA flood risk teams and their supply chain partners.
GeoSmart also provides property-level analysis for all sources of flooding (FloodSmart Analytics) at 5 m or property (UPRN) level. LLFAs and other public bodies can use it for portfolio, community, town and city-level estimates of annual damage (based on the Flood Hazard Research Centre’s “Multi-coloured manual” database of property loss and damage to provide consistent local and national estimates of annual damage from all four main sources of flooding). It turns the NaFRA data from a binary “in or out” of a zone into an analysis based on annual average loss, which puts groundwater on the same footing as surface water, rivers and coastal risk for like-for-like comparison. The platform and the property-level products are included in the 50% offer for public bodies.
A note on what GW200 shows
GW200 presents the boundary between the “negligible” and “low” risk zones of GW5. Every 200 m cell is shown in one of two classes:
- Negligible risk of groundwater flooding.
- Potential risk of groundwater flooding in the 200 m cell.
This means that the cells showing “potential risk” indicate that there could be flood risk within that square, flagging it for more detailed assessment. We therefore take a precautionary screening approach, consistent with the precautionary principle enshrined in tiered environmental risk assessment practice. You can then use GW5 to obtain a higher resolution confirmation of where there may be groundwater risk on a 5 m grid nationwide.
Where GW200 shows negligible risk, our national model is not showing a risk. Please note that this is not the same as no risk. It may be, but local groundwater conditions that are not modelled can cause flooding in these areas, so where the consequences of a decision are important, always obtain a site-specific groundwater assessment.
Get started
- Download the free GW200 screening map. You will receive a download link by email after you complete a short form and accept the licence.
- Take up the 50% offer: tick the contact box on the download form, email enquiries@geosmartinfo.co.uk, or call 01743 298100.
- Learn more, or obtain GW5 data: visit www.geosmartinfo.co.uk.
- Want to understand the data first? We are happy to arrange a call.
GeoSmart Information Ltd is a flood risk specialist modeller and developer of flood risk maps for all sources of flooding
