Gipsy Hill Flood Alleviation Scheme

Updated - November 2025

Due to the high frequency of highway flooding in the Gipsy Hill area Southwark Council is introducing a scheme in Long Meadow to address this issue.

Why is this happening?

The Thames Water (TW) surface water sewers serving Dulwich Wood Avenue and Gipsy Hill are separate. The factor restricting effective surface water management on Dulwich Wood Avenue is the hydraulic efficiency of the highway gullies, rather than the sewer network. The Dulwich Wood Avenue gullies, do not have the hydraulic capacity to capture the surface water runoff volumes during large storm events. Therefore, excess surface water bypasses the TW Dulwich Wood Avenue surface water sewer system and flows overland towards Gipsy Hill, exacerbating flooding in the lower lying area. As a result, surface water flows overland around the northern end of the park.

The proposed Sustainable Drainage System (SuDS) scheme aims to address the capacity issues of the highway gullies on Dulwich Wood Avenue. By utilising the natural topography, the proposed SuDS features intercept and manage surface water, reducing overland flows toward Gipsy Hill.

How will the SuDS scheme help?

The proposed SuDS scheme is designed to intercept and manage surface water on Dulwich Wood Avenue using the area’s natural topography. Key features include:

• Redirecting surface water flows at higher elevations before they reach Gipsy Hill.
• Reducing the volume of water bypassing the existing drainage system.
• Mitigating overland flooding in Long Meadow Park and Gipsy Hill.

The Environmental Agency (EA) Risk of Surface Water Flooding data (shown in the map below) demonstrates that the areas at risk in large storm events extends from Dulwich Wood Avenue, across Long Meadow Park, down to the northern end of Gipsy Hill.

Expected benefits

The SuDS scheme will significantly reduce surface water flooding risks in the area. It will capture runoff from:

• 200 m² of Dulwich Wood Park,
• 2,260 m² of Dulwich Wood Avenue, and
• 12,900 m² of Long Meadow Park.

By enhancing the capacity to manage surface water, the SuDS will not only improve flood resilience but also contribute to a more sustainable and environmentally friendly solution for the community.

After consulting residents, we’ve updated the design based on your feedback.

What’s Changed?

• Two main channels instead of one – to spread water more evenly and handle heavy rainfall.
• Bioswales moved further into the park – protecting existing trees and wildlife.
• Larger footprint – to divert more water away from roads and Long Meadow towards the attenuation features.
• Improved pipework – better collection from Dulwich Wood Avenue and Dulwich Wood Park for greater efficiency.
• Improved public amenity - benches, stepping stones and bridges have been included in the design to benefit the local community and provide an engaging space for residents to sit, play and enjoy the green space.