Policy paper

Thames groundwater situation: 26 November 2024

Updated 26 November 2024

Applies to England

Current situation

Groundwater levels across the Thames catchment continue to generally rise following the rainfall from Storm Bert. Levels at 2 locations have reached levels that require early awareness.

Groundwater levels in the Lambourn Valley, West Berkshire and the Upper Og Valley in Wiltshire have exceeded the trigger threshold. This briefing note provides an update on the levels at both locations. It also includes links to a range of websites containing further information.

Lambourn Valley

Groundwater levels at the Longacre Borehole in the Lambourn Valley continue to rise. They are still at an early awareness level. The rate of rise has increased over the last few days following the heavy rainfall.

We still do not currently expect any groundwater alerts to be issued within the next few weeks. We will continue to monitor the situation closely and issue further briefing notes and alerts if the situation changes.

Upper Og Valley

Groundwater levels at the Draycot Foliat observation borehole in the Upper Og Valley reacted to the recent rainfall and rose steeply. However, they are currently levelling off.

Groundwater levels at this site tend to respond quickly to heavy rain. We will continue to monitor the situation closely and issue further briefing notes and alerts if the situation changes.

Summary of other groundwater sites

Levels at our groundwater sites are generally higher than normal for the time of year and have responded to recent rainfall. Most have an increasing trend.

Forecast risk of flooding

Met Office weather forecasts indicate that the first part of December could be quite settled, the second half of the month could be wetter and windier.

The forecast can be seen in the Met Office’s long range forecast.

More details can also be found in the monthly water situation report for England.

What we’re doing

We are:

• continuing to monitor groundwater levels across the area
• removing blockages from rivers in the area to ensure they flow freely
• talking with the local authority and other responding partners to ensure they are aware of the situation

Actions and advice

Call Floodline on 0345 988 118 or visit check for flooding on GOV.UK to find out if you can register to receive free flood alerts for flooding from groundwater.

You can monitor daily groundwater levels at the Longacre Borehole at Groundwater level at Longacre.

You can view historic levels for Longacre and other sites on the Hydrology Data Explorer.

Check the river, sea, groundwater and rainfall levels on GOV.UK.

You should:

• review your individual and community group flood plans
• check pumps and any other flood protection equipment you have
• keep drains and gullies around your property free of debris
• move valuables from basements and cellars

Next update

Flood risk increases with the continuing rising groundwater. We will update this briefing note weekly for as long as one or more sites exceed the notification levels. We will also issue updates if the situation changes significantly.

Further information

See more information on groundwater levels and the water situation report.

You can also get practical advice on what to do before, during and after groundwater flooding and see the flood forecast for the next 5 days. Visit check for flooding in England.

Contacts

For more information on the flood alert service and to find out what messages you are registered to receive, call Floodline on 0345 988 118.

Alternatively, you can contact the Environment Agency for more information:

• customers and engagement: enquiries_THM@environment-agency.gov.uk
• national customer contact centre: 03708 506 506
• incident reporting hotline: 0800 807 060