Research and analysis

Groundwater situation: Hampshire 16 February 2024

Updated 23 February 2024

Current situation

Groundwater levels across Hampshire remain high due to an extremely wet autumn and winter. From 5 January 2024 to 5 February 2024, the weather was relatively dry. Groundwater levels in most susceptible communities were able to reduce significantly during this time. However, since 6 February 2024, unsettled weather bringing heavy and persistent rain returned to Hampshire. The rate at which groundwater levels have been falling has slowed, and in some communities, levels have stabilised or even started to increase slowly again.

Groundwater flooding impacts have generally reduced in the last month, but most susceptible communities continue to be affected by minor impacts. These include water in fields, flowing on roads and in a small number of basements. The sewerage network and septic tanks in numerous villages will continue to be affected.

Figure 1: Graph showing changes in groundwater levels in Oakley Borehole in North Hampshire from January 2022 to February 2024. The graph shows a steep incline in groundwater level from the end of October 2023. Groundwater levels are currently high, but stable.

Figure 2: Graph showing changes in groundwater levels in Hursley Borehole in central Hampshire from January 2022 to February 2024. The graph shows a steep incline in groundwater level from the end of October 2023. Groundwater levels are currently high, but slowly falling.

Figure 3: Graph showing changes in groundwater levels in Whitedale Farm Borehole in East Hampshire from January 2022 to February 2024. The graph shows a steep incline in groundwater level from the end of October 2023 and a steep decline during January 2024. Groundwater levels have just started to slowly rise again.

Weather forecast

Mostly dry weather is forecast for the rest of today (16 February) and for most of Saturday (17 February).

During Saturday evening, a frontal system will move across Hampshire bringing 10mm of rain to most communities. Some locations could see totals of up to 30mm of rain. This system is expected to clear away to the east early on Sunday morning (18 February). Widely dry and settled conditions are expected for the rest of Sunday (18 February), Monday (19 February) and Tuesday (20 February).

Long range forecasting is difficult, but a return to more unsettled conditions from Wednesday (21 February) is currently the most likely scenario. There is a potential for heavy periods of rain in the United Kingdom at times in the latter half of the week.

Forecast risk of flooding

The exact groundwater response will depend on the amount, intensity and distribution of rainfall that occurs.

Groundwater levels remain sensitive to heavy rainfall. If heavy or persistent rain does affect Hampshire before the end of February, it is possible that groundwater levels could rise quickly, and flooding impacts could increase. In some communities in north and central Hampshire, it is possible that internal ground flood flooding could occur if heavy rain occurs during the next couple of weeks.

However, if drier than average rain is recorded over the next few weeks, groundwater levels will decrease, and flooding impacts will reduce. If this occurs, Flood Alerts will begin to be removed over the coming weeks.

Next update

We will update this groundwater situation document by 15 March 2024, or sooner if the risk of groundwater flooding significantly increases. When in force, groundwater Flood Alerts are updated with information more frequently.

What we are doing

We continue to monitor groundwater levels and their response to rainfall.

Throughout autumn and winter, we will update this groundwater situation and our groundwater Briefing Notes.

We will issue and update flood alerts when there is risk of flooding affecting property.

We liaise with the local authority and other responding partners to ensure they are aware of the situation.

Our operational staff removing blockages from main rivers, to ensure they flow freely.

Actions and advice

Think and prepare now for what you’ll do if flooding occurs where you live, don’t wait until flooding happens.

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

Look for data in your area:

• groundwater data
• river, sea, groundwater and rainfall levels

There is practical advice on what to do before, during and after groundwater flooding, and further guidance about groundwater flooding, how it might affect you and what to do.

Prepare a personal flood plan or community flood plan to help you and your community decide what practical actions to take before and during a flood, which will help reduce the damage flooding could cause.

Check pumps and any other flood protection equipment you have. Ensure valuables are moved from basements and other low parts of properties.

Where safe to do so, communities may wish to check and ensure there are no blockages in local watercourses and ditches.

Further information

You can view:

• daily groundwater levels compared to average and maximum, with indicative impact thresholds
• sub daily groundwater levels on Gaugemap
• the latest flood alert information
• groundwater situation information for North Hampshire (Alton, Basingstoke, Crondall, Farringdon, Sherborne St John)
• water situation reports

More detailed groundwater briefing notes are emailed as part of the flood alert service. See contacts section below to register your email address.

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 following for additional information:

• Environment Agency Customers and Engagement: ssdenquiries@environment-agency.gov.uk
• Environment Agency Incident Reporting Hotline: 0800 807060
• Environment Agency National Customer Contact Centre: 03708 506 506