Research and analysis

Wessex (Dorset and South Wiltshire) groundwater situation: 11 December 2020

Updated 14 December 2020

Applies to England

Current situation

There are currently no groundwater flood alerts for Salisbury Plain, Cranborne Chase and the West of Dorset.

The latest summary of the water situation in the south west gives details of the rainfall, groundwater levels and river flows.

Wessex received ‘normal’ rainfall in November 2020 at 84% long term average (LTA) (71 mm). There were multiple bands of rain throughout November; the most notable event occurred on 14 November, when 23% of the month’s rain fell. The last week of November was generally dry.

Groundwater increased at all reporting sites, whilst the majority had ‘normal’ levels for the time of year.

West of Dorset

In the West of Dorset, the level at the Kingston Russell borehole, on 9 December 2020, was 109.2 metres above sea level (mAOD). The level was 117.1mAOD this time last year. The borehole is currently classed as ‘normal’ for this time of year. Levels at the Kingston Russell borehole are still above normal for this time of year.

Groundwater levels at the Kingston Russell borehole

Cranborne Chase

In Cranborne Chase, the current level at the West Woodyates borehole, is 90.7 mAOD. This is 6.3 metres below the level at this time last year. In January 2014, the borehole reached its highest ever recorded level of 109mAOD. In February 2020, levels reached 106.7mAOD. The borehole is currently classed as ‘normal’ for the time of year.

Groundwater levels at the Woodyates borehole

Salisbury Plain

On Salisbury Plain, the current level in the Tilshead borehole, is 85.1mAOD. The borehole is currently classed as ‘normal’ for the time of year. The level is 7.5m below the level at this time last year.

Groundwater levels at the Tilshead borehole

Forecast risk of flooding

More details of the forecast predictions can be found in the Water Situation Report for England.

What we are doing

For several years the Environment Agency has been able to issue groundwater flood alerts across the area. The 3 alert areas are the West of Dorset, Cranborne Chase and Salisbury Plain. The flood alert is an early warning about the potential for flooding to occur.

A flood warning is used to warn people that flooding is expected. Please check to see whether your area is covered by a groundwater flood warning area. The Environment Agency is working on a 5 year programme to develop a groundwater flood warnings service for groundwater affected communities across Wiltshire and Dorset. If you have any knowledge of historic or recent groundwater flooding within your community, please contact flood.wessex@environment-agency.gov.uk.

The Environment Agency is continuing to develop new groundwater flood warning areas across Dorset and Wiltshire. Currently we have 34 groundwater flood warning areas and are working with communities to expand the service to other locations. The groundwater flood warnings cover smaller areas than the flood alerts and are more community based. You can sign-up to the flood warning service.

Groundwater levels are high and we encourage residents to sign up to groundwater flood warnings within your parish and to check your flood plans are in place.

To find out if you are at risk and to register to receive these flood alerts and flood warnings for groundwater, call Floodline on 0345 988 118 (24 hour service) or sign up to flood warnings.

Actions and advice

• think and prepare now for what you’ll do if flooding occurs where you live, don’t wait until flooding happens
• if you have a personal flood plan you should put it into action
• move valuables from basements and cellars
• if you have a pump ensure it is serviced and working effectively
• keep drains and gullies around your property free of debris
• you may need to improve surface water drainage and/or install and assess sump pumping arrangements
• view local water levels and flooding information
• if you own part of the river bank you should keep the banks and bed of the river clear of debris
• we are encouraging parishes at risk to develop a Community flood plan, identifying local issues and working with the different agencies to prepare and respond to flooding

Next update

The next update will be mid January 2021 unless the situation changes.

Further information

• The current status of the flood alert for the West of Dorset
• The current status of the flood alert for Cranborne Chase
• The current status of the flood alert for Salisbury Plain

Contacts

If you would like any further information on groundwater levels in the area please email floodwessex@environment-agency.gov.uk.

Alternatively ring Floodline 0345 988 118 or the Incident Hotline on 0800 80 70 60.