Groundwater Situation Report
Wessex (Dorset & South Wiltshire) Update 26 August 2014
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, giving details of the rainfall, ground water levels and river flows for July can found at:
South West Water Situation Report - July
Rainfall across the Southwest in July was below average for the time of year with Wessex receiving about 80% of the long term average. This is only the fourth month since last October (the start of the water year) that rainfall was average or below average. This is the wettest calendar year and the wettest water year on record for the South West.
Groundwater levels are generally higher than they would be for the time of year and this is affecting the flow in groundwater fed rivers, especially the winterbournes. There are several cases where winterbournes are still flowing, when they would normally be dry at this time of year.
Despite being at high levels all boreholes are showing a general downward trend (recession). Some of the more reactive boreholes in West Dorset and the South Wiltshire Downs have shown minor increases following some of the intense rainfall events we have had.
In the West of Dorset, the level at the Kingston Russell borehole, on 26/08/2014 is 106.68 metres above sea level (mAOD). At its peak in mid February it reached 121.13mAOD.
In Cranborne Chase the current level, at the West Woodyates borehole is 74.86 mAOD. In January the borehole reached its highest recorded level of 109.23 mAOD. Despite falling by nearly 30 metres the level is still notably high.
Woodyates Ranking derived from data for the period Jan-1942 to Dec-2012
102
97
92
87
82
Level (mAOD) Level 77 72
67 Oct-12 Jan-13 Apr-13 Jul-13 Oct-13 Jan-14 Apr-14 Jul-14
On Salisbury Plain the current level in the Tilshead borehole, is 82.74mAOD. For much of January and February the borehole reached its maximum level and was said to be artesian, this is where the groundwater reaches the surface.
Tilshead Ranking derived from data for the period Jan-1966 to Dec-2012
97
92
87
(mAOD) Level 82
77 Oct-12 Jan-13 Apr-13 Jul-13 Oct-13 Jan-14 Apr-14 Jul-14 Tilshead Borehole was artesian for January and February 2014
Forecast risk of flooding
Currently the pattern of recession is following what normally happens in summer and it is expected that groundwater will continue to drop.
Our groundwater predication models indicate that groundwater levels at the beginning of October (the start of the new water year) are generally likely to be above normal.
If these patterns are extended until March 2015 there is a greater than expected chance that levels will be above normal at the end of the winter.
More details of the predictions can be found in the monthly Water Situation Report for England. This can be found at:
Monthly Water Situation Report - England
What we are doing
Groundwater levels are being monitored regularly to look at the trends in recession. Information gathered over the last two winters is being used to produce a more targeted flood warning. This will enable us to issue warnings for specific communities rather than the wider flood alerts. In October we will have 23 community specific flood warning areas across the West of Dorset, Cranborne Chase and Salisbury Plain. We will be talking to communities to promote this service in September and October.
We are also working hard to ensure that the defences we operate are functioning effectively (trash screens, pumps, flood storage areas) and will take action to clear removing blockages from rivers in the area to ensure they flow freely.
Actions and advice
To find out if you are at risk and to register to receive Flood Alerts for groundwater call Floodline on 0345 988 118 or 0845 988 1188 (24 hour service) or go online at www.environment-agency.gov.uk. (Please check your call plan as some customers may find the 0845 number is cheaper than the 0345 number).
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. • Visit the Environment Agency website www.environment-agency.gov.uk for 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 should it occur later in the year.
If you have flooded
The government has introduced a number of measures to support people who have flooded. These include council tax relief and a scheme for householders to put in place resilience measures to help reduce the effect of flooding on their properties. These measures are being administered by the relevant local authorities. Further details about these measures can be found on the Wiltshire Council website (Wiltshire Flood Support) and the "Dorset for You" website (Dorset Flood Support )
Next update
The next update will be in early October,at the start of the new water year, unless the situation changes.
Further information
To see the current status of the flood alert for Salisbury Plain follow the link: Groundwater on Salisbury Plain
To see the current status of the flood alert for Cranborne Chase follow the link: Groundwater on Cranborne Chase
To see the current status of the flood alert for the West of Dorset follow the link: Groundwater in West Dorset
Contacts
If you would like any further information on groundwater levels in the area please contact us by emailing [email protected] . Please use this email to report incidences of groundwater flooding.
Alternatively ring Floodline 0345 988 118 or the National Incident Hotline on 0800 80 70 60