Flood Alert Issued for Groundwater Flooding in Upper River Ems Valley, West Sussex

Alert Details

The Environment Agency has issued a Flood Alert (Severity Level 3) for groundwater flooding in the Upper River Ems Valley. The alert was officially raised on March 2, 2026, at 5:03 PM local time, following observations that groundwater levels at the Compton borehole are high and very close to the surface.

Affected Areas

The alert covers the Solent and South Downs area within West Sussex. Specific geographic impacts are noted in the following locations:

• Stoughton: Main road and local cellars.
• Walderton: Area between Cooks Lane and Barley Mow, and local cellars.
• East Marden: The road leading from the village.
• Woodlands Lane: The B2146 near this junction.

What You Should Do

Residents in the affected areas are advised to take the following precautions:

• Road Safety: Exercise extreme caution on flooded roads, particularly the Stoughton main road and the road from East Marden.
• Property Maintenance: Residents in Stoughton and Walderton should ensure that cellar pumps are in good working order to manage potential groundwater ingress.
• Monitoring: Stay informed of updates as conditions evolve.

Expected Conditions

Groundwater levels are currently very close to the surface but are slowly falling at the Compton borehole. Despite the slow decline, springs will continue to appear, and water is expected to remain in fields and flow across several roads. A small number of cellars in Stoughton and Walderton are likely to be affected by the high water table. Only small amounts of rainfall are forecast for the five-day period ending March 6, 2026.

Timeline

The alert is currently active and groundwater flood impacts are expected to continue until at least the middle of March 2026. While settled conditions and high pressure are suggested for the first half of the month, the Environment Agency will provide a formal update on the situation by 6:00 PM on March 6, 2026.