Coastal Restoration Trust of New Zealand

Coastal Dune Ecosystem Reference Database

Preparing for sea-level rise through adaptive managed retreat of a New Zealand stormwater and wastewater network Journal Paper

Author
Kool, R.; Lawrence, J.; Drews, M.; Bell, R.
Year
2020
Journal / Source
Infrastructures
Volume
5
Number
11
Pages
19
Summary
Low-lying and exposed coastal communities rely upon the delivery of stormwater and wastewater services which in these types of coastal areas, are often located together underground. Due to sea-level rise and associated compounding climate-related hazards, managing these networks will become progressively harder for local governments. Responsible agencies must reconcile whether such networks can continue to be adapted/protected over time to retain levels of service, or whether eventual retreat may be the only viable adaptation option. If retreat is chosen, at what performance threshold should this occur? In this paper, we explore these questions for stormwater and wastewater, using a dynamic adaptive pathway planning (DAPP). Dynamic adaptive strategies for managed retreats can help reduce future disruption from coastal flooding, signal land use changes early, inform maintenance, and allow for gradual budget adjustments. Involving key local stakeholders, we use DAPP to identify thresholds for stormwater and wastewater services and retreat options, and for developing a comprehensive and area-specific retreat strategy. The result is a prototype for an area near Wellington, New Zealand, where a managed retreat of water infrastructure is being considered. We present this process in a pathway form that can be communicated spatially and visually, helping to make retreat a more manageable adaptation option for water agencies, and the communities they serve.