Preparing for Sea-Level Rise through Adaptive Managed Retreat of a New Zealand Stormwater and Wastewater Network

Abstract

Sea-level rise increasingly affects low-lying and exposed coastal communities due to climate change. These communities rely upon the delivery of stormwater and wastewater services which are often co-located underground in coastal areas. Due to sea-level rise and associated compounding climate-related hazards, managing these networks will progressively challenge local governments as climate change advances. Thus, responsible agencies must reconcile maintaining Levels of Service as the impacts of climate change worsen over the coming decades and beyond. A critical question is 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 so, at what performance threshold? In this paper, we explore these questions for stormwater and wastewater, using a dynamic adaptive pathway planning (DAPP) approach designed to address thresholds and increasing risk over time. Involving key local stakeholders, we here use DAPP to identify thresholds for stormwater and wastewater services and retreat options, and for developing a comprehensive and area-specific retreat strategy comprising pathway portfolios, retreat phases, potential land use changes, and for exploring pathway conflicts and synergies. The result is a prototype for an area near Wellington, New Zealand, where a managed retreat of water infrastructure is being considered at some future juncture. Dynamic adaptive strategies for managed retreats can help to reduce future disruption from coastal flooding, signal land use changes early, inform maintenance, and allow for gradual budget adjustments by the agencies that can manage expenditure over time. We present this stepwise process in a pathway form that can be communicated spatially and visually, thereby making a retreat a more manageable, sequenced, adaptation option for water agencies, and the communities they serve.

Managed retreat and planned retreat: a systematic literature review

“…The arts/theatre plays feature as a potential communication tool [128]. Enabling community acceptance though incrementally implemented managed retreat is found to allow time for appropriate communications but also provides time for a community to adjust to the idea [129]. Cohn et al [130] detail seven Californian case study localities, where managed retreat had attempted to be implemented but had failed.…”

Impact of sea level rise on the land cover structure in Southeast Asia

“…In this situation, it is necessary to prepare a long-term policy of conduct by the governments of the countries of the region. One of the potential solutions is the adoption of a retreat policy and the slow relocation of arable land to higher areas, combined with an increase in production efficiency through automation and fertilization (Kool et al, 2020). In the long run, this will allow food production to be maintained at an appropriate level to feed a growing population.…”

Phronesis at the Human-Earth Nexus: Managed Retreat

“…The COVID-19 health pandemic illustrates what is reported as systemic for complex-adaptive socio-ecological systems (Termeer et al, 2015(Termeer et al, , 2016Huang and London, 2016;Preiser et al, 2017). Also, the COVID-19 pandemic taught those in charge of decision-making to be aware of unexpected disproportionate consequences of management actions, while at the same time decision-making must be flexible, highly adaptive, fast, and frugal; (see for example Fuerth and Faber, 2012;Munene et al, 2018;Kool et al, 2020).…”