Proposed improvements to the stormwater management system in the Inhlanza Catchment Area located in East London

Buffalo City Metropolitan Municipality (BCMM) have developed proposals to improve the stormwater management in the Inhlanza Catchment Area located in East London, Eastern Cape. The Inhlanza River Catchment, which falls mostly within the residential suburbs of Vincent, Berea, Stirling, Woodleigh and Nahoon. It extends from approximately Frere Road in the North West to the sea outfall near the Nahoon River Mouth in the East. The sub-catchment area between Schultz Road and Galway Road is particularly prone to flooding under current conditions.

The proposed solution to alleviate the flooding experienced between Schultz Road and Galway Road is twofold:
i. The installation of two stormwater detention ponds in the vegetated area of the Neale Road/Chamberlain Road intersection; and
ii. The installation of grass-lined earth berms or gabion basket walls at the section immediately upstream of Schultz Road and along the length of the section between Schultz Road and Drake Road.

The peak flow for a 1:5 year storm event can be reduced from 26.8 m3 /s to 18.7 m3/s by means of the detention ponds, which is a reduction of approximately 30%. The berm/gabion basket structures will act as a barrier and prevent flood water from entering the adjacent properties, and confining the flood waters to the channel and overbank area.

The following infrastructure is proposed:
Two stormwater detention ponds (5000m3 & 1800m3) upstream of Chamberlain Road (32°59'14.40"S, 27°54'34.37"E)
Grass-lined berm/gabion basket wall (40m) upstream of Schultz Road (32°59'20.40"S, 27°55'25.92"E)
Grass-lined berm/gabion basket wall (190m) between Schultz Road and Drake Road (32°59'19.11"S, 27°55'31.09"E)