Current situation

Groundwater levels continue their seasonal rising trend across the Thames catchment. Groundwater flood alerts have been issued at 4 locations, and a further 5 locations are at levels that require early awareness.

Groundwater levels have reached the levels that require groundwater flood alerts in:

• the Lambourn Valley (West Berkshire)
• Great Shefford (West Berkshire)
• West and East Ilsley, Compton, Chilton and West Hagbourne (West Berkshire)
• Henley and Assendon (Oxfordshire)

The levels have also reached the levels that require early awareness at:

• Chapel Wood (Leckhampstead area)
• Lower Farringdon (Alton, Hampshire)
• Upper Aldbourne Valley (Wilts)
• Piddington (Bucks)
• Draycot Foliot (Upper Og valley, Wiltshire)

This briefing note provides an update on the levels at these 9 locations. It also includes links to a range of websites containing further information.

Lambourn Valley

Groundwater levels have risen slightly at the Longacre observation borehole in the Lambourn Valley.

They remain at a level at which groundwater flooding may affect communities.

A groundwater flood alert was issued for this area on 10 December 2024.

This will remain in force over the coming weeks as levels are expected to remain high and sensitive to further sustained periods of rainfall.

Great Shefford

Groundwater levels remain broadly stable at the Northfield Farm observation borehole in the Great Shefford area.

Levels remain at a level at which groundwater flooding may affect communities.

A groundwater flood alert was issued on 10 December 2024.

This will remain in force over the coming weeks as levels are expected to remain high and sensitive to further sustained periods of rainfall.

West and East Ilsley, Compton, Chilton and West Hagbourne

Groundwater levels continue to rise at our Hodcott observation borehole near West and East Ilsley.

Consequently, groundwater is at a level at which flooding may affect communities.

A groundwater flood alert was issued for this area on 30 December 2024.

This will remain in force over the coming weeks as levels are expected to remain high and sensitive to further sustained periods of rainfall.

Henley and Assendon

Groundwater levels continue to rise steadily at our Stonor observation borehole.

Groundwater is at a level where communities may be impacted.

A groundwater flood alert was issued for this area on 21 January 2025.

This will remain in force over the coming weeks as levels are expected to remain high and sensitive to further sustained periods of rainfall.

Leckhampstead

Groundwater levels are above the level that requires early awareness and steadily rising at our Chapel Wood observation borehole.

If the current rate of rise continues, we may consider issuing a groundwater alert within the next few weeks.

We will continue to monitor the situation closely and issue alerts as and when needed.

Upper Aldbourne Valley

Groundwater levels have increased slightly in response to the recent rain at our Water Acre observation.

Levels remain above the level that requires early awareness and responsive to further rainfall.

However, with the current rate of rise, we do not expect to issue a groundwater alert within the coming few weeks.

We will continue to monitor closely and issue alerts as and when needed.

Upper Og Valley

Groundwater levels have dropped again following last week’s rise at the Draycot Foliat observation borehole in the Upper Og Valley.

Levels at this location are responsive to individual rainfall events and will remain sensitive to further rainfall.

We will continue to monitor the situation closely and issue alerts as and when needed.

Alton, East Hampshire

Groundwater levels have been rising steadily but have stabilised over the last week at our Farringdon observation borehole, near Alton.

If levels rise again, we may issue a groundwater alert within the coming few weeks.

We will continue to monitor the situation closely and issue alerts as and when needed.

Piddington

Groundwater levels are rising steadily at the Piddington observation borehole near West Wycombe and High Wycombe, Buckinghamshire.

Levels have reached the early awareness level and remain responsive to further rainfall.

However, with the current rate of rise, we do not expect to issue a groundwater alert within the coming few weeks.

We will continue to monitor closely and issue alerts as and when needed.

Summary of other groundwater sites

Levels at our groundwater sites are generally higher than normal. Most have an increasing trend. This rising trend is expected to continue in response to the winter recharge. We continue to monitor groundwater levels and will update this briefing note and issue flood alerts as and when needed.

Forecast risk of flooding

The Met Office monthly weather forecast indicates that the current changeable conditions will continue for some time.

Their forecast is regularly updated.  

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
• monitoring and clearing screens on main rivers in the area to ensure they flow freely
• updating local authorities and other responding partners to ensure they are aware of the situation if necessary

Actions and advice

To find out if you can register to receive free flood alerts for flooding from groundwater:

• call Floodline on 0345 988 118
• use the check for flooding service

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

You can monitor daily groundwater levels at the Hodcott borehole (West and East Illsley, Compton, Chilton and West Hagbourne) at Groundwater level at Hodcott.

You can monitor groundwater levels for the Northfield Farm observation borehole (Great Shefford) at Groundwater level at Northfield Farm.

You can monitor groundwater levels for the Chapel Wood observation boreholde (Leckhampstead) at Groundwater level at Chapel Wood.

You can monitor groundwater levels for the Water Acre observation borehole (Upper Aldbourne Valley, Wiltshire) at Groundwater level at Water Acre.

Groundwater levels for the Piddington observation borehole (High Wycombe, Buckinghamshire) can be found at Groundwater level at Piddington.

Groundwater levels for the Stonor observation borehole (Assendon and Henley area, Oxfordshire) can be found at Groundwater level at Stonor.

Groundwater levels for the Lower Farringdon observation borehole (Alton, East Hampshire) can be found at Groundwater level at Lower Farringdon.

You can view historic levels for our sites on the Hydrology Data Explorer. This includes Draycot Foliat.

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