Research and analysis

Kimpton and Lilley Bottom, north Hertfordshire: groundwater situation

Updated 11 April 2024

Applies to England

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Groundwater levels – April 2024

Groundwater levels in the Kimpton and Lilley Bottom area are considerably higher than expected for this time of year, which could result in groundwater flooding. Groundwater flooding occurs when underground water levels begin to rise above the surface.

The Environment Agency is monitoring levels and issuing a groundwater flood alert due to the risk of groundwater flooding in this area.

Current situation

The Kimpton and Lilley Bottom area has seen exceptionally high rainfall, with 157% of the long-term average rainfall falling between October 2023 and April 2024. Groundwater levels have risen substantially in response to this and soils remain saturated across the area.

The Lilley Bottom Observation Borehole readings show that groundwater levels are currently high. They are only around 0.7 metre below the levels reached in the flooding incident of 2001, where there was significant and widespread flooding.

Forecast risk of flooding

As indicated above, groundwater levels are unusually high and there is currently a risk of groundwater flooding, which could result in localised surface flooding. It could also result in water flowing in usually dry chalk valleys and fields becoming waterlogged in the area.

The main areas at risk of groundwater flooding are in and around Kimpton, including Lye Hill, Whiteway and Claggy Bottom. Along the upper River Mimram Valley, the area along Lilley Bottom from Chalk Hill to Law Hall Lane is most at risk.

We expect groundwater levels to remain high for the next month or two, but we expect the risk of flooding to decrease due to the warmer and drier spring weather. If groundwater flooding does occur, due to the high groundwater levels it can last for several weeks or months.

What we’re doing

We are monitoring the situation closely and will continue to do so. Our systems are monitoring water levels at the Lilley Bottom Observation Borehole every hour and its response to further rainfall.

We will be talking to the local authority and other responding partners as the situation changes to make sure they are aware of the latest updates. We will support our partners’ responses in managing any flooding impacts.

Actions and advice

The following information could help you to reduce the impact of groundwater flooding.

To find out more about your flood risk and prepare for future flooding:

Groundwater can infiltrate sewer systems. If you have problems flushing your toilet or sewage is emerging, contact Thames Water Utilities on 0800 316 9800.

Some practical steps you can take to prepare for flooding and minimise the impact to you, your property and possessions are to:

  • prepare a flood kit including a torch, batteries, mobile phone, warm clothes, water, food and any prescription medicines you may need
  • move valuables from basements and cellars
  • check pumps and any other flood protection equipment you have
  • keep drains and gullies around your property free of debris
  • keep an eye on local water levels and weather conditions

Unfortunately, there are no measures available to lower the water table during a groundwater flood. Residents and businesses:

  • must be prepared for groundwater levels remaining high
  • should undertake measures to protect their property until the water table naturally falls

The most important thing to do to prepare for groundwater flooding is to have a personal flood plan.

Groundwater flooding can be difficult as homes, roads and community spaces can all be affected for long periods of time. If you are struggling and would like someone to talk to, the National Flood Forum is a charity to help, support and represent people at risk of flooding. You can call them on 01299 403 055.

Project Groundwater supports communities to be more resilient to groundwater flooding. The project aims to increase engagement with communities to help build understanding and awareness of groundwater flooding. They are working to: 

  • improve monitoring of when and where groundwater emerges
  • develop a better groundwater flood warning service that will support residents to act
  • investigate what nature-based solutions could be used to reduce groundwater flood risk

Defra is funding this project as part of the flood and coastal resilience programmes – Engage Environment Agency. The Environment Agency is managing the programmes. They will drive innovation in flood and coastal resilience and adaptation to a changing climate.

Find out more about Project Groundwater.

Next update 

The next scheduled update is for Wednesday 17 April 2024. We will update this briefing note sooner if the situation changes significantly.

Groundwater levels may stay high for several weeks. Remember that flood water will also stay around for some time until groundwater levels recede.

Further information

Check the latest flood alerts and warnings.

Read our weekly and monthly water situation reports for England.

Contacts

  • Floodline: 0345 988 1188
  • Environment Agency Hertfordshire and North London (HNL) enquiries: hnlenquiries@environment-agency.gov.uk
  • Environment Agency National Customer Contact Centre: 03708 506 506
  • Environment Agency Incident Hotline (Freephone 24hr service): 0800 80 70 60
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