Solutions to erosion and flooding in Southshore, South New Brighton to be considered

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Proposed options - costing about $12.5 million - to address erosion and flood risk in Southshore and South New Brighton will be considered by the Christchurch City Council this week.

"Earthquake legacy issues have been an ongoing concern for Southshore and South New Brighton residents," says council head of planning and strategic transport, David Griffiths.

"Residents have made it clear to us that, before they are willing to have a conversation about how their area could respond to sea level rise in the future, they want these issues resolved."

"This report aims to address some of those concerns by providing recommendations for how we can reduce the risk of erosion and flooding along the estuary edge."

Council staff proposed to replace or cover structures along the estuary edge in Southshore to reduce the erosion risk.

This approach has community support, and would also significantly improve the appearance of the estuary edge, Griffiths said.

To reduce the risk of flooding in Southshore, council staff recommend the construction of an 11.4 RL bund close to the current Land Information New Zealand bund.

In South New Brighton, the council propose to restore the estuary edge with a cobble beach.

To reduce the flooding risk, it is recommended a new bund be set up 100m from the estuary edge within South New Brighton Park, between the jetty near Beatty Street and the southern end of the campground in Halsey Street.

These options are in response to several council resolutions from August last year regarding earthquake legacy issues.

Improvements have already been made to the northern part of the estuary walkway and construction is complete on the southern section of a bund in South New Brighton, between Bridge Street and South New Brighton School.

Work on the northern section of the bund will be completed next year following the bird-nesting season.

Minor issues have been addressed following an assessment of the stopbank between Pages Road and Bridge Street.

The assessment showed the stopbank meets current standards.

Engineering consultancy GHD is now undertaking an updated life-safety risk assessment of the stopbank and this will be a separate report to council once the investigation is complete.

The proposed options to address erosion and flooding risk are forecast to cost about $12.5m. The draft 2021-31 Long Term Plan allows for $10.5m.