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

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.

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

10.26686/wgtn.14502864 ◽

2021 ◽

Author(s):

R Kool ◽

Judith Lawrence ◽

M Drews ◽

R Bell

Keyword(s):

Climate Change ◽

Land Use ◽

New Zealand ◽

Sea Level Rise ◽

Sea Level ◽

Local Governments ◽

Land Use Changes ◽

Adaptation Option ◽

Levels Of Service ◽

Over Time

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.

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Preparing for Sea-Level Rise through an Adaptive Managed Retreat of a Two-Waters Network

10.20944/preprints202007.0630.v1 ◽

2020 ◽

Cited By ~ 1

Author(s):

Rick Kool ◽

Judy Lawrence ◽

Martin Drews ◽

Robert Bell

Keyword(s):

Climate Change ◽

Land Use ◽

Sea Level Rise ◽

Sea Level ◽

Land Use Changes ◽

Climate Change Impacts ◽

Adaptation Option ◽

Water Sensitive Urban Design ◽

Levels Of Service ◽

Over Time

Frequent flooding from sea-level rise (SLR) is one of the immediate climate change impacts affecting low-lying and exposed coastal communities. These communities rely upon the delivery of three-waters services for wastewater, stormwater and water supply. Due to ongoing SLR, managing these networks will increasingly be a challenge. This raises the issue of how local government can reconcile maintaining levels of service as the impacts of climate change and their uncertainties worsen over the coming decades (and beyond). Can they be adapted over time to retain levels of service or will they eventually require retreat and if so at what adaptation threshold? This paper explores managed retreat of two-waters infrastructure (wastewater and stormwater) as an adaptation option using a Dynamic Adaptive Pathway Planning (DAPP) approach. In the study, we use DAPP to frame the retreat of two-water networks, developing a combination of an area specific retreat strategy, pathway portfolios, retreat phases, land use change signaling and identify pathway conflicts and synergies. Repurposing retreated areas by utilizing Water Sensitive Urban Design (WSUD) options was found to extend retreat thresholds for adjacent areas. A systematic ’routine’ developed in this study provides a structured approach for managed retreat of two-water infrastructure with the aim to reduce future disruption from flooding, signal land use changes early and allow for gradual budget adjustments by the agencies to manage expenditure over time. This approach helps inform and improve the decision-making process for the agencies and the communities they serve, by providing a stepwise process that can be communicated spatially and visually, thereby making a retreat adaptation option more manageable.

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Managed Retreat Components and Costing in a Coastal Setting

10.26686/wgtn.17138906.v1 ◽

2021 ◽

Author(s):

◽

Samuel Olufson

Keyword(s):

Climate Change ◽

Sea Level Rise ◽

Sea Level ◽

Local Governments ◽

Adaptation Strategy ◽

Adaptation Option ◽

Future Research ◽

Depth Analysis ◽

Adaptation Options ◽

Over Time

<p>Climate change impacts are beginning to be felt across the world. Therefore, the development and understanding of adaptation options is becoming more important. Sea-level rise and its associated impacts are predicted to continue and accelerate well into the next century. As such, it is important that adaptation options which reduce risks associated with sea-level rise are developed and are well understood. Managed retreat is one such option. While research on managed retreat is increasing, there is a lack of literature that identifies what managed retreat comprises, how to plan and stage the option over time, and how to cost it as an adaptation option. This thesis aims to address this gap in the literature by answering the following three questions: (1) what are the issues related to implementing managed retreat as an adaptation strategy in coastal areas, now, and moving into the future?; (2) what are the components of managed retreat?; and (3) what framework could be developed for costing managed retreat? A qualitative ‘desk-top’ approach was taken to deconstruct the components of managed retreat across space and time and to develop a framework for costing the components as part of an adaptation strategy. An in-depth analysis of literature, enabled an understanding of managed retreat implementation, and also informed the development of a component typology and costing framework for the adaptation option. The typology and framework were then tested for relevance and utility for decision making through a series of semi-structured discussions with key informants working in climate change adaptation. Using the component typology and costing framework, a new approach is presented for staging and costing managed retreat, over time and in different contexts. The typology and framework contribute knowledge and guidance for local governments and infrastructure agencies when discussing managed retreat with their communities, for identifying and staging managed retreat, and for the costing of components. It does this by presenting components in stages as overlapping and parallel pathways, providing groupings of components according to types of costs, and identifying appropriate costing methodologies that enable the implementation of managed retreat. To conclude, the thesis suggests areas for future research on managed retreat.</p>

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Managed Retreat Components and Costing in a Coastal Setting

10.26686/wgtn.17138906 ◽

2021 ◽

Author(s):

◽

Samuel Olufson

Keyword(s):

Climate Change ◽

Sea Level Rise ◽

Sea Level ◽

Local Governments ◽

Adaptation Strategy ◽

Adaptation Option ◽

Future Research ◽

Depth Analysis ◽

Adaptation Options ◽

Over Time

<p>Climate change impacts are beginning to be felt across the world. Therefore, the development and understanding of adaptation options is becoming more important. Sea-level rise and its associated impacts are predicted to continue and accelerate well into the next century. As such, it is important that adaptation options which reduce risks associated with sea-level rise are developed and are well understood. Managed retreat is one such option. While research on managed retreat is increasing, there is a lack of literature that identifies what managed retreat comprises, how to plan and stage the option over time, and how to cost it as an adaptation option. This thesis aims to address this gap in the literature by answering the following three questions: (1) what are the issues related to implementing managed retreat as an adaptation strategy in coastal areas, now, and moving into the future?; (2) what are the components of managed retreat?; and (3) what framework could be developed for costing managed retreat? A qualitative ‘desk-top’ approach was taken to deconstruct the components of managed retreat across space and time and to develop a framework for costing the components as part of an adaptation strategy. An in-depth analysis of literature, enabled an understanding of managed retreat implementation, and also informed the development of a component typology and costing framework for the adaptation option. The typology and framework were then tested for relevance and utility for decision making through a series of semi-structured discussions with key informants working in climate change adaptation. Using the component typology and costing framework, a new approach is presented for staging and costing managed retreat, over time and in different contexts. The typology and framework contribute knowledge and guidance for local governments and infrastructure agencies when discussing managed retreat with their communities, for identifying and staging managed retreat, and for the costing of components. It does this by presenting components in stages as overlapping and parallel pathways, providing groupings of components according to types of costs, and identifying appropriate costing methodologies that enable the implementation of managed retreat. To conclude, the thesis suggests areas for future research on managed retreat.</p>

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Assessment of the exposure level to saltwater intrusion in the context of climate change at Dong Nai province to 2030

Science and Technology Development Journal - Natural Sciences ◽

10.32508/stdjns.v1it4.474 ◽

2017 ◽

Vol 1 (T4) ◽

pp. 255-264

Author(s):

Tuan Ngoc Le ◽

Hoang Xuan Tran

Keyword(s):

Climate Change ◽

Sea Level Rise ◽

Sea Level ◽

Local Governments ◽

Saltwater Intrusion ◽

Exposure Level ◽

Exposure Index ◽

High Exposure ◽

Low Exposure ◽

Over Time

The study aimed to assess the exposure level (E) to saltwater intrusion (SI) in the context of climate change (CC) at Dong Nai province to 2030. The results serve to assess vulnerability due to this phenomenon. The research scope included 57 wards in Bien Hoa city, Long Thanh, and Nhon Trach districts where have been facing to SI. Results showed that: (i) The high exposure area (E ≥ 75): near Long Tau, Dong Tranh, Go Gia rivers and Thi Vai river downstream; (ii) The medium – high exposure area (50 ≤ E < 75): Thi Vai river upstream, Nha Be, and Long Tau rivers; (iii) The medium – low exposure area (25 < E < 50): Dong Nai river above the confluence with Saigon river about 10 km and the area between Dong Mon and Thi Vai rivers; (iv) The low exposure area (E ≤ 25): the entire of Bien Hoa city, a part of Long Thanh district located near Buong river, part 4 of Dong Nai river, and Thi Vai river upstream.The exposure level tends to increase over time (2020, 2030) and under CC scenarios. The differences between the current E and that in 2030 are relatively small: 8.6, 1.96, and 2.71 in Bien Hoa, Long Thanh, and Nhon Trach, respectively. Thus, effects of climate change and sea level rise to the exposure level to SI are not really clear in the period 2014–2030. However, the increase in exposure index partly reflects the challenges for local governments and communities in response to SI and CC.

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Rekonstrukcija recentnih morfoloških promjena žala uz pomoć metode ponovljene fotografije – primjer žala Zogon na otoku Hvaru (Srednji Jadran)

Geoadria ◽

10.15291/geoadria.1412 ◽

2018 ◽

Vol 22 (2) ◽

pp. 165 ◽

Cited By ~ 2

Author(s):

Sanja Faivre ◽

Marin Mićunović

Keyword(s):

Climate Change ◽

Land Use ◽

Sea Level Rise ◽

Sea Level ◽

Land Use Changes ◽

The Other ◽

Recent Climate ◽

Anthropogenic Processes ◽

Photography Method ◽

Construction Works

The geomorphological system composed of a torrent and a beach on the Island of Hvar was analysed with the aim to define natural and anthropogenic processes which influence changes in beach morphology. Using repeat photography method, ortho-photo images and field mapping it was found that between the 60s of the last century and the present, the Zogon beach reduced in size by approximately 50%. The reduction of the beach size can be related to the recent anthropological activities in the wider study area particularly due to multiply filling of the torrent bed during construction works and minor land use changes, as well as due to natural reforestation which all cause a decrease in the supply of material to the beach. On the other hand, the reversal of the beach evolution in the observed period, which is, by definition the accumulative relief form, from the accumulative state or state of balance, to dominant erosion, can be associated with recent climate change and relative sea level rise.

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