Future Changes in Built Environment Risk to Coastal Flooding, Permanent Inundation and Coastal Erosion Hazards

Sea-level rise will cause erosion of land, deeper and increasingly frequent flooding and will eventually permanently inundate low-elevation land, forcing the adaptation of seaside communities to avoid or reduce risk. To inform adaptation planning, we quantified the effects of incremental relative sea-level rise (RSLR) on exposed land area, number and replacement value of buildings within Tauranga Harbour, New Zealand. The assessment compared three coastal hazards: flooding, permanent inundation and erosion. Increasingly frequent coastal flooding will be the dominant trigger for adaptation in Tauranga. In the absence of adaptation, coastal flooding, recurring at least once every 5 years on average, will overtake erosion as the dominant coastal hazard after about 0.15–0.2 m RSLR, which is likely to occur between the years 2038–2062 in New Zealand and will rapidly escalate in frequency and consequence thereafter. Coastal erosion will remain the dominant hazard for the relatively-few properties on high-elevation coastal cliffs. It will take 0.8 m more RSLR for permanent inundation to reach similar impact thresholds to coastal flooding, in terms of the number and value of buildings exposed. For buildings currently within the mapped 1% annual exceedance probability (AEP) zone, the flooding frequency will transition to 20% AEP within 2–3 decades depending on the RSLR rate, requiring prior adaptive action. We also compared the performance of simple static-planar versus complex dynamic models for assessing coastal flooding exposure. Use of the static-planar model could result in sea level thresholds being reached 15–45 years earlier than planned for in this case. This is compelling evidence to use dynamic models to support adaptation planning.

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Quantifying Uncertainty in Exposure to Coastal Hazards Associated with Both Climate Change and Adaptation Strategies: A U.S. Pacific Northwest Alternative Coastal Futures Analysis

Water ◽

10.3390/w13040545 ◽

2021 ◽

Vol 13 (4) ◽

pp. 545

Author(s):

Alexis K. Mills ◽

Peter Ruggiero ◽

John P. Bolte ◽

Katherine A. Serafin ◽

Eva Lipiec

Keyword(s):

Climate Change ◽

Sea Level Rise ◽

Sea Level ◽

Performance Metrics ◽

Coastal Flooding ◽

Water Levels ◽

Coastal Hazards ◽

Policy Decisions ◽

Management Decisions ◽

Quantifying Uncertainty

Coastal communities face heightened risk to coastal flooding and erosion hazards due to sea-level rise, changing storminess patterns, and evolving human development pressures. Incorporating uncertainty associated with both climate change and the range of possible adaptation measures is essential for projecting the evolving exposure to coastal flooding and erosion, as well as associated community vulnerability through time. A spatially explicit agent-based modeling platform, that provides a scenario-based framework for examining interactions between human and natural systems across a landscape, was used in Tillamook County, OR (USA) to explore strategies that may reduce exposure to coastal hazards within the context of climate change. Probabilistic simulations of extreme water levels were used to assess the impacts of variable projections of sea-level rise and storminess both as individual climate drivers and under a range of integrated climate change scenarios through the end of the century. Additionally, policy drivers, modeled both as individual management decisions and as policies integrated within adaptation scenarios, captured variability in possible human response to increased hazards risk. The relative contribution of variability and uncertainty from both climate change and policy decisions was quantified using three stakeholder relevant landscape performance metrics related to flooding, erosion, and recreational beach accessibility. In general, policy decisions introduced greater variability and uncertainty to the impacts of coastal hazards than climate change uncertainty. Quantifying uncertainty across a suite of coproduced performance metrics can help determine the relative impact of management decisions on the adaptive capacity of communities under future climate scenarios.

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Applying principles of uncertainty within coastal hazard assessments to better support coastal adaptation

10.26686/wgtn.14349251.v1 ◽

2021 ◽

Author(s):

SA Stephens ◽

RG Bell ◽

Judith Lawrence

Keyword(s):

Sea Level Rise ◽

Sea Level ◽

Flood Hazard ◽

Coastal Flooding ◽

Coastal Hazards ◽

Time Range ◽

Coastal Hazard ◽

Adaptive Planning ◽

Groundwater Levels ◽

Hazard Assessments

© 2017 by the authors. Coastal hazards result from erosion of the shore, or flooding of low-elevation land when storm surges combine with high tides and/or large waves. Future sea-level rise will greatly increase the frequency and depth of coastal flooding and will exacerbate erosion and raise groundwater levels, forcing vulnerable communities to adapt. Communities, local councils and infrastructure operators will need to decide when and how to adapt. The process of decision making using adaptive pathways approaches, is now being applied internationally to plan for adaptation over time by anticipating tipping points in the future when planning objectives are no longer being met. This process requires risk and uncertainty considerations to be transparent in the scenarios used in adaptive planning. We outline a framework for uncertainty identification and management within coastal hazard assessments. The framework provides a logical flow from the land use situation, to the related level of uncertainty as determined by the situation, to which hazard scenarios to model, to the complexity level of hazard modeling required, and to the possible decision type. Traditionally, coastal flood hazard maps show inundated areas only. We present enhanced maps of flooding depth and frequency which clearly show the degree of hazard exposure, where that exposure occurs, and how the exposure changes with sea-level rise, to better inform adaptive planning processes. The new uncertainty framework and mapping techniques can better inform identification of trigger points for adaptation pathways planning and their expected time range, compared to traditional coastal flooding hazard assessments.

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Applying principles of uncertainty within coastal hazard assessments to better support coastal adaptation

10.26686/wgtn.14349251 ◽

2021 ◽

Author(s):

SA Stephens ◽

RG Bell ◽

Judith Lawrence

Keyword(s):

Sea Level Rise ◽

Sea Level ◽

Flood Hazard ◽

Coastal Flooding ◽

Coastal Hazards ◽

Time Range ◽

Coastal Hazard ◽

Adaptive Planning ◽

Groundwater Levels ◽

Hazard Assessments

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Monitoring Vegetation Dynamics at a Tidal Marsh Restoration Site: Integrating Field Methods, Remote Sensing and Modeling

Estuaries and Coasts ◽

10.1007/s12237-021-00977-4 ◽

2021 ◽

Author(s):

Alexandra S. Thomsen ◽

Johannes Krause ◽

Monica Appiano ◽

Karen E. Tanner ◽

Charlie Endris ◽

...

Keyword(s):

Sea Level Rise ◽

Sea Level ◽

Soil Analysis ◽

High Elevation ◽

Vegetation Monitoring ◽

Field Methods ◽

Bare Area ◽

Marsh Restoration ◽

Restoration Success ◽

Restoration Strategies

AbstractSea level rise threatens coastal wetlands worldwide, and restoration projects are implementing strategies that decrease vulnerability to this threat. Vegetation monitoring at sites employing new restoration strategies and determination of appropriate monitoring techniques improve understanding of factors leading to restoration success. In Central California, soil addition raised a degraded marsh plain to a high elevation expected to be resilient to sea level rise over the next century. We monitored plant survival and recruitment using area searches, transect surveys, and unoccupied aircraft systems (UAS) imagery. We used random forest modeling to examine the influence of nine environmental variables on vegetation colonization and conducted targeted soil sampling to examine additional factors contributing to vegetation patterns. Limited pre-construction vegetation survived soil addition, likely due to the sediment thickness (mean = 69 cm) and placement method. After 1 year, about 10% of the initially bare area saw vegetation reestablishment. Elevation and inundation frequency were particularly critical to understanding restoration success, with greatest vegetation cover in high-elevation areas tidally inundated < 0.85% of the time. Soil analysis suggested greater salinity stress and ammonium levels in poorly-vegetated compared to well-vegetated areas at the same elevation. We found that both transect and UAS methods were suitable for monitoring vegetation colonization. Field transects may provide the best approach for tracking early vegetation colonization at moderate-sized sites under resource limitations, but UAS provide a complementary landscape perspective. Beyond elucidating patterns and drivers of marsh dynamics at a newly restored site, our investigation informs monitoring of marsh restoration projects globally.

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Using Virtual Reality in Sea Level Rise Planning and Community Engagement—An Overview

Water ◽

10.3390/w13091142 ◽

2021 ◽

Vol 13 (9) ◽

pp. 1142

Author(s):

Juliano Calil ◽

Geraldine Fauville ◽

Anna Carolina Muller Queiroz ◽

Kelly L. Leo ◽

Alyssa G. Newton Mann ◽

...

Keyword(s):

Climate Change ◽

Virtual Reality ◽

Sea Level Rise ◽

Sea Level ◽

Community Outreach ◽

Coastal Communities ◽

Coastal Hazards ◽

Multidisciplinary Teams ◽

Simple Task ◽

Coastal Risks

As coastal communities around the globe contend with the impacts of climate change including coastal hazards such as sea level rise and more frequent coastal storms, educating stakeholders and the general public has become essential in order to adapt to and mitigate these risks. Communicating SLR and other coastal risks is not a simple task. First, SLR is a phenomenon that is abstract as it is physically distant from many people; second, the rise of the sea is a slow and temporally distant process which makes this issue psychologically distant from our everyday life. Virtual reality (VR) simulations may offer a way to overcome some of these challenges, enabling users to learn key principles related to climate change and coastal risks in an immersive, interactive, and safe learning environment. This article first presents the literature on environmental issues communication and engagement; second, it introduces VR technology evolution and expands the discussion on VR application for environmental literacy. We then provide an account of how three coastal communities have used VR experiences developed by multidisciplinary teams—including residents—to support communication and community outreach focused on SLR and discuss their implications.

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