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

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.

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

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.

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

2017 ◽  
Author(s):  
Scott A. Stephens ◽  
Robert G. Bell ◽  
Judy Lawrence
Keyword(s):  
Sea Level Rise ◽  
Sea Level ◽  
Planning Process ◽  
Time Range ◽  
Coastal Hazard ◽  
Deep Uncertainty ◽  
Coastal Inundation ◽  
Inundation Depth ◽  
Decision Points ◽  
Hazard Assessments

Coastal inundation is an increasing problem. Sea-level rise will greatly increase the frequency and depth of inundation, forcing vulnerable communities to adapt. Communities will need to decide when and how to adapt. The process of decision-making along adaptive pathways is now being used internationally to plan for adaptation over time by anticipating decision points in the future however it unfolds. This process requires risk and uncertainty considerations to be transparent in the scenarios used in such planning. We outline a framework for uncertainty identification and management within coastal hazard assessments which recognizes different types of decision and identifies the types of uncertainty that must be accounted for, such as statistical, scenario and deep uncertainty types. We show how coastal-inundation hazard can be mapped and presented in a way that clearly separates sources of uncertainty, so that they are transparent within a dynamic adaptive pathways planning process. Traditional coastal inundation maps show inundated area only. We present maps of inundation depth and frequency which clearly show the degree of exposure, where that exposure occurs, and how much sea-level rise can be tolerated. The new uncertainty framework and mapping techniques can better identify decision points and their expected time range, which provides more useful input to the adaptation process than traditional coastal inundation assessments.

scholarly journals 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 ◽  
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.

scholarly journals Coastal Flooding in the Maldives Induced by Mean Sea-Level Rise and Wind-Waves: From Global to Local Coastal Modelling

2021 ◽  
Vol 8 ◽  
Author(s):  
Angel Amores ◽  
Marta Marcos ◽  
Rodrigo Pedreros ◽  
Gonéri Le Cozannet ◽  
Sophie Lecacheux ◽  
...  
Keyword(s):  
Climate Change ◽  
Sea Level Rise ◽  
Sea Level ◽  
Large Scale ◽  
Land Reclamation ◽  
Flood Hazard ◽  
Wind Waves ◽  
Coastal Flooding ◽  
Major Drawback ◽  
Mean Sea Level

The Maldives, with one of the lowest average land elevations above present-day mean sea level, is among the world regions that will be the most impacted by mean sea-level rise and marine extreme events induced by climate change. Yet, the lack of regional and local information on marine drivers is a major drawback that coastal decision-makers face to anticipate the impacts of climate change along the Maldivian coastlines. In this study we focus on wind-waves, the main driver of extremes causing coastal flooding in the region. We dynamically downscale large-scale fields from global wave models, providing a valuable source of climate information along the coastlines with spatial resolution down to 500 m. This dataset serves to characterise the wave climate around the Maldives, with applications in regional development and land reclamation, and is also an essential input for local flood hazard modelling. We illustrate this with a case study of HA Hoarafushi, an atoll island where local topo-bathymetry is available. This island is exposed to the highest incoming waves in the archipelago and recently saw development of an airport island on its reef via land reclamation. Regional waves are propagated toward the shoreline using a phase-resolving model and coastal inundation is simulated under different mean sea-level rise conditions of up to 1 m above present-day mean sea level. The results are represented as risk maps with different hazard levels gathering inundation depth and speed, providing a clear evidence of the impacts of the sea level rise combined with extreme wave events.

scholarly journals COASTAL FLOODING, WAVE OVERTOPPING AND BEACH GROUNDWATER INTERACTIONS

2018 ◽  
pp. 13
Author(s):  
Timu Gallien ◽  
Marie-Pierre Delisle
Keyword(s):  
Sea Level Rise ◽  
Sea Level ◽  
High Water ◽  
Coastal Flooding ◽  
Field Observations ◽  
Wave Overtopping ◽  
Sea Levels ◽  
Groundwater Levels ◽  
Primary Driver ◽  
Global Mean

Coastal flooding is a significant humanitarian and socioeconomic hazard (e.g., Nicholls, 2010). Global mean sea levels are expected to rise over the coming century and mean higher high water (MHHW) and mean high water (MHW), peak levels that drive coastal flooding, show upward trends in many locations (Mawdsley et al., 2015). Significant coastal flooding will occur by 2050 (e.g., Tebaldi et al., 2012; Sweet and Park, 2014). Wave overtopping is primary driver of coastal flooding. Low-lying urbanized sand spits, backed by an estuary are particularly vulnerable to sea level rise. Recent field observations suggest distinct feedbacks between wave overtopping, beach groundwater levels and backshore vulnerability.

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

2021 ◽  
Vol 9 (9) ◽  
pp. 1011
Author(s):  
Scott Stephens ◽  
Ryan Paulik ◽  
Glen Reeve ◽  
Sanjay Wadhwa ◽  
Ben Popovich ◽  
...  
Keyword(s):  
New Zealand ◽  
Sea Level Rise ◽  
Sea Level ◽  
Coastal Erosion ◽  
Dynamic Models ◽  
Coastal Flooding ◽  
High Elevation ◽  
Coastal Hazards ◽  
Adaptation Planning ◽  
Exceedance Probability

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.

scholarly journals An integrated framework of coastal flood modelling under the failures of sea dikes: a case study in Shanghai

2021 ◽  
Author(s):  
Qian Ke ◽  
Jiangshan Yin ◽  
Jeremy D. Bricker ◽  
Nicholas Savage ◽  
Erasmo Buonomo ◽  
...  
Keyword(s):  
Sea Level Rise ◽  
Sea Level ◽  
Flood Hazard ◽  
Discharge Rate ◽  
Coastal Flooding ◽  
Water Volume ◽  
Coastal Flood ◽  
Sea Dikes ◽  
And Sea Level

AbstractClimate change leads to sea level rise worldwide, as well as increases in the intensity and frequency of tropical cyclones (TCs). Storm surge induced by TC’s, together with spring tides, threatens to cause failure of flood defenses, resulting in massive flooding in low-lying coastal areas. However, limited research has been done on the combined effects of the increasing intensity of TCs and sea level rise on the characteristics of coastal flooding due to the failure of sea dikes. This paper investigates the spatial variation of coastal flooding due to the failure of sea dikes subject to past and future TC climatology and sea level rise, via a case study of a low-lying deltaic city- Shanghai, China. Using a hydrodynamic model and a spectral wave model, storm tide and wave parameters were calculated as input for an empirical model of overtopping discharge rate. The results show that the change of storm climatology together with relative sea level rise (RSLR) largely exacerbates the coastal hazard for Shanghai in the future, in which RSLR is likely to have a larger effect than the TC climatology change on future coastal flooding in Shanghai. In addition, the coastal flood hazard will increase to a large extent in terms of the flood water volume for each corresponding given return period. The approach developed in this paper can also be utilized to investigate future flood risk for other low-lying coastal regions.

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

Geosciences ◽  
2019 ◽  
Vol 9 (5) ◽  
pp. 239 ◽  
Author(s):  
Carlos Antunes ◽  
Carolina Rocha ◽  
Cristina Catita
Keyword(s):  
Sea Level Rise ◽  
Sea Level ◽  
Extreme Event ◽  
Flood Hazard ◽  
Atlantic Coast ◽  
Hazard Index ◽  
Coastal Hazards ◽  
Storm Events ◽  
Extreme Flood ◽  
Probabilistic Flooding

Portugal’s 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 adapted and protected from natural coastal hazards, 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 on the Atlantic Coast of Portugal’s mainland was evaluated for 2025, 2050, and 2100 over the whole extension due to SLR, with different sea level scenarios for different extreme event return periods. A coastal probabilistic flooding map was produced based on the developed probabilistic cartography methodology using geographic information system (GIS) technology. The Extreme Flood Hazard Index (EFHI) was determined on probabilistic flood bases using five probability intervals of 20% 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).

Future scenarios of coastal flooding in north-east Italy

2020 ◽  
Author(s):  
Riccardo Giusti ◽  
Mario Martina ◽  
Clara Armaroli ◽  
Rui Figuereido ◽  
Francesco Dottori
Keyword(s):  
Climate Change ◽  
Sea Level Rise ◽  
Sea Level ◽  
Large Scale ◽  
Flood Hazard ◽  
Coastal Flooding ◽  
Human Consumption ◽  
Future Scenarios ◽  
Subsidence Rate ◽  
North East

<p>Climate change and subsidence will likely have a significant role to increase coastal flooding risk. The socio-economic impact of inundations can be very relevant, and, in a context of climate change, it is necessary to develop effective methods for assessing coastal flood hazard suitable for large-scale studies. This work focuses on the application of a new modelling approach for mapping flooding hazard for future scenarios characterized by sea level rise and ground lowering due to subsidence. The flood intensity index approach (Iw, Dottori et al. 2015) will be used to quantitatively evaluate the flood extent. This recent methodology allows to create reliable scenarios with low computational costs. The effects of the storm surge are assessed using a base scenario corresponding to 100 years return period event. IW inputs are represented by water height set as storm level plus a part of wave height. The scenarios will be created by quantitatively combining IPCC sea level rise projections with subsidence data that will be compared to high-resolution digital terrain models. The study area of this work is the ∼205 km long coastal plain of Northern Italy, from Venice to Rimini, composed of low-lying sandy beaches and which includes the Po delta area. The coast is characterized by large portions of the territory below mean sea level and by geological features made by recent quaternary sediments which have a natural subsidence rate. In the past (1960-1980) the subsidence rate had an exceptional increase caused by excessive groundwater withdrawal for agricultural and industrial activities, human consumption and by natural gas extraction.</p>

scholarly journals Coastal Flood Assessment Due to Sea Level Rise and Extreme Storm Events - Case Study of the Atlantic Coast of Portugal Mainland

2019 ◽  
Author(s):  
Carlos Antunes ◽  
Carolina Rocha ◽  
Cristina Catita
Keyword(s):  
Sea Level Rise ◽  
Sea Level ◽  
Extreme Event ◽  
Flood Hazard ◽  
Atlantic Coast ◽  
Hazard Index ◽  
Storm Events ◽  
Coastal Hazard ◽  
Gis Technology ◽  
Extreme Flood

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).

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