Coastal Flood Assessment due to Sea Level Rise and Extreme Storm Events: A Case Study of the Atlantic Coast of Portugal’s Mainland

Portugal Mainland has hundreds of thousands of people living in the Atlantic coastal zone, with numerous high economic value activities and a high number of infrastructures that must be protected from natural coastal hazard, namely extreme storms and sea level rise (SLR). In the context of climate change adaptation strategies, a reliable and accurate assessment of the physical vulnerability to SLR is crucial. This study is a contribution to the implementation of flooding standards imposed by the European Directive 2007/60/EC, which requires each member state to assess the risk associated to SLR and floods caused by extreme events. Therefore, coastal hazard in the Continental Atlantic coast of Portugal Mainland was evaluated for 2025, 2050 and 2100 in the whole coastal extension with different sea level scenarios for different extreme event return periods and due to SLR. A coastal flooding probabilistic map was produced based on the developed methodology using Geographic Information Systems (GIS) technology. The Extreme Flood Hazard Index (EFHI) was determined on flood probabilistic bases through five probability intervals of 20% of amplitude. For a given SLR scenario, the EFHI is expressed, on the probabilistic flooding maps for an extreme tidal maximum level, by five hazard classes ranging from 1 (Very Low) to 5 (Extreme).

Download Full-text

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.

Download Full-text

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

© 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.

Download Full-text

Impact Assessment Analysis of Sea Level Rise in Denmark: A Case Study of Falster Island, Guldborgsund

Sustainability ◽

10.3390/su13137503 ◽

2021 ◽

Vol 13 (13) ◽

pp. 7503

Author(s):

Alexander Boest-Petersen ◽

Piotr Michalak ◽

Jamal Jokar Arsanjani

Keyword(s):

Climate Change ◽

Impact Assessment ◽

Sea Level Rise ◽

Sea Level ◽

Alternative Methods ◽

Projection Data ◽

Storm Events ◽

Cascading Effects ◽

Local Levels

Anthropogenically-induced climate change is expected to be the contributing cause of sea level rise and severe storm events in the immediate future. While Danish authorities have downscaled the future oscillation of sea level rise across Danish coast lines in order to empower the coastal municipalities, there is a need to project the local cascading effects on different sectors. Using geospatial analysis and climate change projection data, we developed a proposed workflow to analyze the impacts of sea level rise in the coastal municipalities of Guldborgsund, located in Southeastern Denmark as a case study. With current estimates of sea level rise and storm surge events, the island of Falster can expect to have up to 19% of its landmass inundated, with approximately 39% of the population experiencing sea level rise directly. Developing an analytical workflow can allow stakeholders to understand the extent of expected sea level rise and consider alternative methods of prevention at the national and local levels. The proposed approach along with the choice of data and open source tools can empower other communities at risk of sea level rise to plan their adaptation.

Download Full-text

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.

Download Full-text

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.

Download Full-text

Impact of climate change on New York City’s coastal flood hazard: Increasing flood heights from the preindustrial to 2300 CE

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.1703568114 ◽

2017 ◽

Vol 114 (45) ◽

pp. 11861-11866 ◽

Cited By ~ 73

Author(s):

Andra J. Garner ◽

Michael E. Mann ◽

Kerry A. Emanuel ◽

Robert E. Kopp ◽

Ning Lin ◽

...

Keyword(s):

New York ◽

New York City ◽

Sea Level Rise ◽

Sea Level ◽

Tropical Cyclones ◽

York City ◽

Flood Hazard ◽

Storm Surges ◽

Cmip5 Models ◽

Tidal Level

The flood hazard in New York City depends on both storm surges and rising sea levels. We combine modeled storm surges with probabilistic sea-level rise projections to assess future coastal inundation in New York City from the preindustrial era through 2300 CE. The storm surges are derived from large sets of synthetic tropical cyclones, downscaled from RCP8.5 simulations from three CMIP5 models. The sea-level rise projections account for potential partial collapse of the Antarctic ice sheet in assessing future coastal inundation. CMIP5 models indicate that there will be minimal change in storm-surge heights from 2010 to 2100 or 2300, because the predicted strengthening of the strongest storms will be compensated by storm tracks moving offshore at the latitude of New York City. However, projected sea-level rise causes overall flood heights associated with tropical cyclones in New York City in coming centuries to increase greatly compared with preindustrial or modern flood heights. For the various sea-level rise scenarios we consider, the 1-in-500-y flood event increases from 3.4 m above mean tidal level during 1970–2005 to 4.0–5.1 m above mean tidal level by 2080–2100 and ranges from 5.0–15.4 m above mean tidal level by 2280–2300. Further, we find that the return period of a 2.25-m flood has decreased from ∼500 y before 1800 to ∼25 y during 1970–2005 and further decreases to ∼5 y by 2030–2045 in 95% of our simulations. The 2.25-m flood height is permanently exceeded by 2280–2300 for scenarios that include Antarctica’s potential partial collapse.

Download Full-text

Compounding effects of sea level rise and fluvial flooding

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.1620325114 ◽

2017 ◽

Vol 114 (37) ◽

pp. 9785-9790 ◽

Cited By ~ 104

Author(s):

Hamed R. Moftakhari ◽

Gianfausto Salvadori ◽

Amir AghaKouchak ◽

Brett F. Sanders ◽

Richard A. Matthew

Keyword(s):

Sea Level Rise ◽

Sea Level ◽

Hazard Assessment ◽

Failure Probability ◽

River Flow ◽

Flood Hazard ◽

High Tide ◽

Probability Method ◽

Flood Hazards ◽

Flood Hazard Assessment

Sea level rise (SLR), a well-documented and urgent aspect of anthropogenic global warming, threatens population and assets located in low-lying coastal regions all around the world. Common flood hazard assessment practices typically account for one driver at a time (e.g., either fluvial flooding only or ocean flooding only), whereas coastal cities vulnerable to SLR are at risk for flooding from multiple drivers (e.g., extreme coastal high tide, storm surge, and river flow). Here, we propose a bivariate flood hazard assessment approach that accounts for compound flooding from river flow and coastal water level, and we show that a univariate approach may not appropriately characterize the flood hazard if there are compounding effects. Using copulas and bivariate dependence analysis, we also quantify the increases in failure probabilities for 2030 and 2050 caused by SLR under representative concentration pathways 4.5 and 8.5. Additionally, the increase in failure probability is shown to be strongly affected by compounding effects. The proposed failure probability method offers an innovative tool for assessing compounding flood hazards in a warming climate.

Download Full-text

National guidance for adapting to coastal hazards and sea-level rise: Anticipating change, when and how to change pathway

Environmental Science & Policy ◽

10.1016/j.envsci.2018.01.012 ◽

2018 ◽

Vol 82 ◽

pp. 100-107 ◽

Cited By ~ 21

Author(s):

Judy Lawrence ◽

Rob Bell ◽

Paula Blackett ◽

Scott Stephens ◽

Sylvia Allan

Keyword(s):

Sea Level Rise ◽

Sea Level ◽

Coastal Hazards ◽

National Guidance ◽

And Sea Level

Download Full-text

Sustained coral reef growth in the critical wave dissipation zone of a Maldivian atoll

Communications Earth & Environment ◽

10.1038/s43247-021-00338-w ◽

2022 ◽

Vol 3 (1) ◽

Author(s):

Paul S. Kench ◽

Edward P. Beetham ◽

Tracey Turner ◽

Kyle M. Morgan ◽

Susan D. Owen ◽

...

Keyword(s):

Sea Level Rise ◽

Sea Level ◽

Coastal Hazards ◽

Reef Crest ◽

Reef Growth ◽

Wave Dissipation ◽

Short Term ◽

Ecological Processes ◽

Reef Accretion ◽

Direct Measurements

AbstractSea-level rise is expected to outpace the capacity of coral reefs to grow and maintain their wave protection function, exacerbating coastal flooding and erosion of adjacent shorelines and threatening coastal communities. Here we present a new method that yields highly-resolved direct measurements of contemporary reef accretion on a Maldivian atoll reef rim, the critical zone that induces wave breaking. Results incorporate the suite of physical and ecological processes that contribute to reef accumulation and show growth rates vary from 6.6 ± 12.5 mm.y−1 on the reef crest, and up to 3.1 ± 10.2 mm.y−1, and −0.5 ± 1.8 mm.yr−1 on the outer and central reef flat respectively. If these short-term results are maintained over decades, the reef crest could keep pace with current sea-level rise. Findings highlight the need to resolve contemporary reef accretion at the critical wave dissipation zone to improve predictions of future reef growth, and re-evaluate exposure of adjacent shorelines to coastal hazards.

Download Full-text