Flood Alert Issued for Groundwater in Vernham Dean, Upton, and the Bourne Valley

Alert Details

The Environment Agency has issued a flood alert for groundwater flooding affecting Vernham Dean, Upton, and the Bourne Valley. The alert was officially raised on March 10, 2026, at 4:38 PM following sustained high groundwater levels in the Solent and South Downs area.

Affected Areas

The primary geographic focus of this alert is the Bourne Valley in Hampshire. Specific locations mentioned include:

• Upton: Currently experiencing steady groundwater levels with flooding affecting a small number of cellars.
• Vernham Dean: Borehole levels have fallen by 1.08m, though the alert remains in place.
• Hurstbourne Tarrant, Stoke, and St Mary Bourne: Included in the monitoring area, though significant impacts to property are not currently expected in these specific locations.

What You Should Do

Residents in the warning area, particularly those in Upton, are advised to take the following precautions:

• Prepare and deploy property resilience measures.
• Ensure that any installed basement or floor pumps are in good working order.
• Be aware that septic tanks in the area may struggle to operate properly due to the high water table.

Expected Conditions

Groundwater levels remain high throughout the valley. While recent measurements show a decrease of 1.08m at the Vernham Dean borehole, levels at Upton remain relatively steady. Forecasts indicate mostly dry weather for Tuesday, March 10, Wednesday, March 11, and Saturday, March 14. However, a weather system on Thursday, March 12, and Friday, March 13, is expected to bring between 20mm and 25mm of rainfall, which will likely prolong the ongoing groundwater flooding impacts.

Timeline

The alert is currently active as of March 10, 2026. While dry intervals are expected early in the week, the anticipated rainfall on March 12-13 is expected to extend the duration of the hazard. The Environment Agency is closely monitoring the situation and expects to provide a formal update by 6:00 PM on March 17, 2026.