Flood Alert Issued for Groundwater 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 within the Solent and South Downs area. The alert was officially raised on March 9, 2026, at 10:29 AM local time.

Affected Areas

The alert specifically covers the upper River Ems Valley in West Sussex. Impacted locations include:

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

What You Should Do

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

• Exercise extreme caution on flooded roads, particularly in Stoughton and Walderton.
• Ensure that cellar pumps are in good working order to manage potential groundwater ingress.
• Monitor local conditions as springs continue to appear and water flows into fields and onto roadways.

Expected Conditions

Groundwater levels are currently high and very close to the surface. While levels are slowly falling at the Compton borehole, springs are expected to continue appearing. Water is currently flowing down several major roads and affecting a small number of cellars. Although bands of rain are forecast for Wednesday, March 11, and Friday, March 13, 2026, only relatively small amounts of precipitation are predicted, which should allow groundwater levels at the Compton borehole to continue their gradual decline.

Timeline

The alert is effective immediately. Groundwater is expected to continue falling throughout the month of March; however, flood impacts may not fully reduce until April. If persistent or exceptional rainfall occurs in late March, impacts may remain for a longer duration. The Environment Agency will provide an updated message by 18:00 on March 13, 2026.