Councillors will receive the latest South Dunedin Future report at Tuesday’s meeting, which provides a tentative shortlist of "potential adaptation futures" for the suburb.
Each of the futures considered consists of a different mix of infrastructure and nature-based solutions, and discusses the need for managed retreat due to flooding and climate change.
Infrastructure will be a key component of all futures, particularly in the short term, but the report notes "large-scale retreat" has been considered "sub-optimal" before 2100.
Instead, the future approach would likely include a mixture of the shortlisted options: elevating land and pumping water, leading to waterways and wetlands and eventually waterways and raised land, the report said.
The status quo would not be sustainable, the modelling found.
South Dunedin Future programme manager Jonathan Rowe said a detailed assessment was undertaken to determine the shortlist.
This assessment considered community feedback from earlier this year, as well as a range of technical and socio-economic factors, such as engineering, urban design and community wellbeing, he said.
"The three shortlisted futures were considered the most suitable for South Dunedin over the next 100 years.
"There’s no quick or easy solution.
"To get the best result, it’s important that we assess options carefully. Over the next few months, we’ll look at each of the three shortlisted futures in depth.
"We’ll assess the risks, costs, timeframes involved in each, and determine the location and scale of the different interventions.
"This will look at things such as where and when a wetland would be most effective, what complementary infrastructure will be needed to reduce flood risk and where or when we should consider managed retreat."
Mr Rowe said infrastructure was likely to play a key role in all potential futures.
"The DCC’s capital work programme will complement the South Dunedin Future programme, with the DCC planning a $60 million spend on wet weather flow management improvements, including in South Dunedin, over the next nine years."
All the preferred options were found to meet the objectives of the community, such as sustainable urban development, environmental and cultural restoration, just transition and social and economic resilience.
The programme is a collaboration between the Dunedin City Council and Otago Regional Council.
The overall aim of South Dunedin Future is to develop a comprehensive climate adaptation master plan for South Dunedin.
Mr Rowe said options such as relocation to raised land and large-scale retreat were likely to need long lead-in times, but "could be useful options in the very long term — beyond 2100".
The fully developed shortlist of potential adaptation futures and pathways for South Dunedin was expected to be completed and presented to the councils in early 2026, he said.
At that point the councils would be asked to consider the futures, endorse them for the purposes of community engagement and provide approval to proceed to the final stage of the South Dunedin Future programme.
