Flood Alert Issued for Upper River Ems Valley in West Sussex Due to High Groundwater

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. Issued on February 23, 2026, the alert notes that while groundwater levels at the Compton borehole are currently falling slowly, they remain high and very close to the surface.

Affected Areas

The alert specifically covers regions in West Sussex, including:

• Stoughton: Main road and a small number of cellars.
• Walderton: Areas between Cooks Lane and Barley Mow, including local cellars.
• East Marden: The road leading from the village.
• B2146: Near Woodlands Lane.

Residents may observe springs appearing in fields and water flowing across local roadways in these specific geographic zones.

What You Should Do

Residents in the warning area are advised to take the following actions:

• Road Safety: Exercise extreme caution when traveling on flooded roads, particularly in Stoughton and Walderton.
• Equipment Check: Ensure that any basement or cellar pumps are in good working order to manage potential water ingress.
• Stay Informed: Monitor local weather updates as conditions are expected to change by the end of the week.

Expected Conditions

Currently, groundwater is high but receding slowly. Isolated showers are forecast from Monday through Wednesday, February 25. However, a weather front is forecast to bring widespread rainfall on Thursday, February 26, 2026. While there is uncertainty regarding exact rainfall amounts, it is probable that groundwater at the Compton borehole will rise again starting Friday, February 27. Levels are not expected to rise significantly higher than they have been so far this winter.

Timeline

• Effective Date: February 23, 2026
• Short-term Forecast: Isolated showers through February 25; widespread rain expected February 26.
• Expected Rise: Groundwater levels likely to rise again from Friday, February 27, through next week.
• Duration: Groundwater flood impacts are expected to continue until the middle of March.
• Next Update: The Environment Agency will update this alert by 18:00 on February 27, 2026.