JBA launches 5m resolution groundwater flood map

Flooding from groundwater is a significant flood risk mechanism in some parts of the UK. It occurs when the position of the groundwater table reaches a much higher level than usual – after a prolonged wet period for example.

This can lead to water being able to locally flood up above ground level, or seep from the surrounding ground into manmade underground structures, including basements, cellars and sewers. Groundwater flooding tends to be more persistent than other types of flooding, in some cases lasting for weeks or months, and because of its duration can result in significant damage to property as well as causing prolonged road closures.

New and improved

We’re the first company to launch a detailed groundwater flood risk map back in 2007 (for the Chalk aquifer) and followed this with national mapping at 50m resolution in 2014. We are now very excited to announce the release of updated mapping using a new and improved method applied at 5m resolution. In creating the new map our expert team of hydrogeologists and flood risk specialists modelled how and where groundwater levels would rise following prolonged periods of rainfall, taking into account factors such as topography, groundwater recharge volumes and spatial variations in aquifer storage and transmission properties. The model outputs were validated against recorded groundwater levels for past flood events and checked against areas historically affected by groundwater flooding.

The enhanced resolution of the new 5m maps makes it easier for users to pinpoint and report risks from groundwater flooding.

Technical Director Maxine Zaidman told us,

“What really sets this map apart from others is the inclusion of 1:50k geological mapping and a 5m resolution digital terrain model as input data sets. This has allowed us not only to very accurately determine where groundwater flooding will be a problem, but to define the scale of the problem as well. More importantly, we have been able to determine the amount of water feeding into different groundwater systems and quantify how this varies with probability. This means we have been able to estimate how high groundwater levels will rise locally, during different design flood return periods, and the knock-on implications for flood risk. The detailed groundwater maps will be invaluable to flood risk management authorities, water companies, property search companies and insurers.”

Want to find out more?

If you would like to know more about our groundwater flood maps and how they can meet your needs please email Maxine Zaidman or call 01756 799919.

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