Multi-Criteria Decision Analysis of Coastal Inundation at Regional scale

2021 ◽  
Author(s):  
Vinay Shivamurthy ◽  
Bharath Aithal
Keyword(s):  
High Risk ◽  
Decision Analysis ◽  
Sea Level Rise ◽  
Sea Level ◽  
Natural Hazards ◽  
Flood Risk ◽  
Sea Levels ◽  
Risk Levels ◽  
Multi Criteria Decision Analysis ◽  
Rising Sea Levels

<p>Coastal flooding are natural processes that are both i) essential (providing nutrients to the coastal vegetation, habitats) and ii) hazardous (negatively impact human activities, livelihood, assets, livestock and so on). Climate changes have induced higher frequency of floods, rising sea levels, high amplitude tides and other climatic extremes at regional to global scales. The increasing intensity, duration of floods is proportionately increasing the risks associated with coastal human habitations. The regional risks are defined based on the physical, demographic, socio-economic vulnerability of the habitants. Sea level rise would further enhance the coastal inundations permanently breaching these productive, densely populated regions. This necessitates the need for spatially assessing the relative hazard, vulnerability and risks at regional scales to reduce/mitigate risks.</p><p>Indian subcontinent supports the second largest global population, with numerous megacities, towns and villages along the coast and mainland. This study's main objective is to quantify the risk associated with inundations caused by rising sea levels, tidal surge at the regional level. As a case study, Sagar Island located in the verge of Sundarbans, south of West Bengal is considered. Flood risk assessment in the island has been carried out using Multi-Criteria Decision Analysis (MCDA) framework based on 23 spatial parameters.</p><p>Results indicate, within a century (1922 – 2020), the island has lost most of its natural vegetation (mangroves - Sundarbans) (47% to 3%), with increasing cultivated (agriculture, horticulture) spaces (77.4 %) and built-up environs (8.2%). Sea level rise varies from 4.4 mm/year (South) to 5.25 mm/year (North) and in the last century has breached over 2824 hectares of mainland. The study's findings reveal 19.8% of horticulture and 33.3% of agriculture assets are highly exposed to natural hazards. 1.34% population are at relatively very high-risk levels, 17.81% at high-risk levels. The study's findings reveal the variable importance of socio-economic, demographic, topographic and proximity to public service, in defining the flood vulnerability and risk towards the habitants. The approach and findings of paves the way for planning authorities to prioritise risk mitigation strategies that are region-specific to reduce the impact of inundation due to natural hazards</p><p><em>Keywords: Sea level rise, Flood risk, MCDA, Vulnerability, flood hazard</em></p>

scholarly journals Coastal Flooding Risk Assessment Using a GIS-Based Spatial Multi-Criteria Decision Analysis Approach

Water ◽  
2020 ◽  
Vol 12 (9) ◽  
pp. 2379
Author(s):  
Vahid Hadipour ◽  
Freydoon Vafaie ◽  
Kaveh Deilami
Keyword(s):  
Risk Assessment ◽  
High Risk ◽  
Decision Analysis ◽  
Sea Level ◽  
Flood Risk ◽  
Social Vulnerability ◽  
Quantitative Methods ◽  
Coastal Flooding ◽  
Rcp Scenarios ◽  
Multi Criteria Decision Analysis

Coastal areas are expected to be at a higher risk of flooding when climate change-induced sea-level rise (SLR) is combined with episodic rises in sea level. Flood susceptibility mapping (FSM), mostly based on statistical and machine learning methods, has been widely employed to mitigate flood risk; however, they neglect exposure and vulnerability assessment as the key components of flood risk. Flood risk assessment is often conducted by quantitative methods (e.g., probabilistic). Such assessment uses analytical and empirical techniques to construct the physical vulnerability curves of elements at risk, but the role of people’s capacity, depending on social vulnerability, remains limited. To address this gap, this study developed a semiquantitative method, based on the spatial multi-criteria decision analysis (SMCDA). The model combines two representative concentration pathway (RCP) scenarios: RCP 2.6 and RCP 8.5, and factors triggering coastal flooding in Bandar Abbas, Iran. It also employs an analytical hierarchy process (AHP) model to weight indicators of hazard, exposure, and social vulnerability components. Under the most extreme flooding scenario, 14.8% of flooded areas were identified as high and very high risk, mostly located in eastern, western, and partly in the middle of the City. The results of this study can be employed by decision-makers to apply appropriate risk reduction strategies in high-risk flooding zones.

scholarly journals Conservation Choices in the Face of Sea-Level Rise: A Case Study on Marsh Migration from Phippsburg, Maine

2017 ◽  
Vol 46 (2) ◽  
pp. 388-419 ◽  
Author(s):  
Sahan T. M. Dissanayake ◽  
Meagan K. Hennessey
Keyword(s):  
Sea Level Rise ◽  
Sea Level ◽  
Land Conservation ◽  
Simulation Data ◽  
Sea Levels ◽  
Decision Method ◽  
The Face ◽  
Rising Sea Levels ◽  
Knapsack Algorithm

We analyze the benefits of incorporating climate change into land conservation decisions using wetland migration under rising sea-levels as a case study. We use a simple and inexpensive decision method, a knapsack algorithm implemented in Excel, with (1) simulation data to show that ignoring sea-level rise predictions lead to suboptimal outcomes, and (2) an application to land conservation in Phippsburg, Maine to show the real-world applicability. The simulation shows an 11-percent to almost 30-percent gain in increased benefits when accounting for sea-level rise. The results highlight that it is possible to, and important to, incorporate sea-level rise into conservation planning.

scholarly journals Socioeconomic and environmental predictors of estuarine shoreline hard armoring

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Nicole E. Peterson ◽  
Craig E. Landry ◽  
Clark R. Alexander ◽  
Kevin Samples ◽  
Brian P. Bledsoe
Keyword(s):  
Sea Level Rise ◽  
Sea Level ◽  
Economic Consequences ◽  
Coastal Hazards ◽  
Environmental Predictors ◽  
Sea Levels ◽  
Shoreline Armoring ◽  
Rising Sea Levels ◽  
Estuarine Shoreline ◽  
The Individual

Abstract Rising sea levels and growing coastal populations are intensifying interactions at the land-sea interface. To stabilize upland and protect human developments from coastal hazards, landowners commonly emplace hard armoring structures, such as bulkheads and revetments, along estuarine shorelines. The ecological and economic consequences of shoreline armoring have garnered significant attention; however, few studies have examined the extent of hard armoring or identified drivers of hard armoring patterns at the individual landowner level across large geographical areas. This study addresses this knowledge gap by using a fine-scale census of hard armoring along the entire Georgia U.S. estuarine coastline. We develop a parsimonious statistical model that accurately predicts the probability of armoring emplacement at the parcel level based on a set of environmental and socioeconomic variables. Several interacting influences contribute to patterns of shoreline armoring; in particular, shoreline slope and the presence of armoring on a neighboring parcel are strong predictors of armoring. The model also suggests that continued sea level rise and coastal population growth could trigger future increases in armoring, emphasizing the importance of considering dynamic patterns of armoring when evaluating the potential effects of sea level rise. For example, evolving distributions of armoring should be considered in predictions of future salt marsh migration. The modeling approach developed in this study is adaptable to assessing patterns of hard armoring in other regions. With improved understanding of hard armoring distributions, sea level rise response plans can be fully informed to design more efficient scenarios for both urban development and coastal ecosystems.

Mapping the soft and ethical dimensions of sea level rise in southern Sweden

2020 ◽  
Author(s):  
Lisa Van Well ◽  
Anette Björlin ◽  
Per Danielsson ◽  
Godefroid Godefroid Ndayikengurukiye ◽  
Gunnel Göransson
Keyword(s):  
Sea Level Rise ◽  
Sea Level ◽  
Coastal Areas ◽  
Ecological Impacts ◽  
Gis Mapping ◽  
Ethical Values ◽  
Southern Sweden ◽  
Sea Levels ◽  
Rising Sea Levels

<p>Sea level rise poses profound challenges within current municipal and regional governance since it requires unusually long planning horizons, is surrounded by great uncertainties, and gives rise to novel ethical challenges. Adaptation to climate change is fundamentally an ethical issue because the aim of any proposed adaptation measure is to protect that which is valued in society. One of the most salient ethical issues discussed in the adaptation literature relates to the distribution of climate related risks, vulnerabilities and benefits across populations and over time. Raising sea-walls is typically associated with high costs and potentially negative ecological impacts as well as substantial equity concerns; managed retreat or realignment often causes problems related to property rights; and migration out of low-lying areas can involve the loss of sense and cultural identity and impact on receiving communities.</p><p>How can the soft and ethical dimensions of rising mean sea levels be characterized and how can their consequences be mapped? To help municipalities to understand the values and ethics attached to measures to deal with long-term rising sea levels in southern Sweden, we are developing a methodology of soft or ethical values to complement to GIS-mapping of coastal vulnerability based on coastal characteristics and socio-economic factors.</p><p>Rather than determining these values a priori, they are being discerned through workshops with relevant stakeholders and in interviews with citizens residing in and utilizing the coastal areas. The methodology attempts to determine the place-based of values within coastal communities with a focus on “whose” values, “what” values, and the long-term or short-term nature of values. It builds on an analytical framework developed to acquire information on the behavior, knowledge, perception and feelings of people living, working and enjoying the coastal areas.  In turn this stakeholder-based information is used to co-create “story maps” as tools to communicate complicated vulnerability analyses, highlight the ethical dimensions of various adaptation measures, raise awareness and aid decisionmakers in taking uncomfortable decisions to “wicked” planning problems around the negative effects of sea level rise, coastal erosion and urban flooding.</p><p>This paper presents the methodological development of the task as well as the results the study in four Swedish municipalities. The representation of the “soft” and ethical values provides an opportunity to help clarify these values to policymakers and increase resilience to rising sea levels.</p>

Interactions of extreme river flows and sea levels for coastal flooding

2020 ◽  
Author(s):  
Peter Robins ◽  
Lisa Harrison ◽  
Mariam Elnahrawi ◽  
Matt Lewis ◽  
Tom Coulthard ◽  
...  
Keyword(s):  
Sea Level Rise ◽  
Sea Level ◽  
West Coast ◽  
Flood Risk ◽  
Coastal Flooding ◽  
Relative Timing ◽  
The West ◽  
Sea Levels ◽  
Flooding Hazards ◽  
Fluvial Response

<p>Coastal flooding worldwide causes the vast majority of natural disasters; for the UK costing £2.2 billion/year. Fluvial and surge-tide extremes can occur synchronously resulting in combination flooding hazards in estuaries, intensifying the flood risk beyond fluvial-only or surge-only events. Worse, this flood risk has the potential to increase further in the future as the frequency and/or intensity of these drivers change, combined with projected sea-level rise. Yet, the sensitivity of contrasting estuaries to combination and compound flooding hazards at sub-daily scales – now and in the future – is unclear. Here, we investigate the dependence between fluvial and surge interactions at sub-daily scales for contrasting catchment and estuary types (Humber vs. Dyfi, UK), using 50+ years of data: 15-min fluvial flows and hourly sea levels. Additionally, we simulate intra-estuary (<50 m resolution) sensitivities to combination flooding hazards based on: (1) realistic extreme events (worst-on-record); (2) realistic events with shifted timings of the drivers to maximise flooding; and (3) modified drivers representing projected climate change.</p><p>For well-documented flooding events, we show significant correlation between skew surge and peak fluvial flow, for the Dyfi (small catchment and estuary with a fast fluvial response on the west coast of Britain), with a higher dependence during autumn/winter months. In contrast, we show no dependence for the Humber (large catchment and estuary with a slow fluvial response on the east coast of Britain). Cross-correlation results, however, did show correlation with a time lag (~10 hours). For the Dyfi, flood extent was sensitive to the relative timing of the fluvial and surge-tide drivers. In contrast, the relative timing of these drivers did not affect flooding in the Humber. However, extreme fluvial flows in the Humber actually reduced water levels in the outer estuary, compared with a surge-only event. Projected future changes in these drivers by 2100 are likely to increase combination flooding hazards: sea-level rise scenarios predicted substantial and widespread flooding in both estuaries. However, similar increases in storm surge resulted in a greater seawater influx, altering the character of the flooding. Projected changes in fluvial volumes were the weakest driver of estuarine flooding. On the west coast of Britain containing many small/steep catchments, combination flooding hazards from fluvial and surges extremes occurring together is likely. Moreover, high-resolution data and hydrodynamic modelling are necessary to resolve the impact and inform flood mitigation methodology.</p>

scholarly journals Future flood risk exacerbated by the dynamic impacts of sea level rise

2020 ◽  
Author(s):  
Matthew Bilskie ◽  
Diana Del Angel ◽  
David Yoskowitz ◽  
Scott Hagen
Keyword(s):  
Sea Level Rise ◽  
Sea Level ◽  
Flood Risk ◽  
Residential Buildings ◽  
Flood Damage ◽  
Coastal Communities ◽  
Modeling Framework ◽  
Sea Levels ◽  
Coastal Landscapes ◽  
Block Level

Abstract A growing concern of coastal communities is an increase in flood risk and non-monetary consequences as a result of climate-induced impacts such as sea level rise (SLR). While previous studies have outlined the importance of quantifying future flood risk, most have focused on broad aggregations of monetary loss using bathtub SLR-type models. Here we quantify, for the first time at the multi-state scale, actual impacts to coastal communities at the census block level using a dynamic, high-resolution, biogeophysical modeling framework that accounts for future sea-levels and coastal landscapes. We demonstrate that future SLR can increase the number of damaged residential buildings by 600%, the population of displaced people by 500% and the need for shelter assistance of up to 460% from present-day conditions. An exponential increase in flood damage associated with increasing sea level deems it essential for stakeholders to plan for plausible future conditions rather than the current reality.

scholarly journals Rising Sea Levels Bring a Tidal Change to Tourism

Eos ◽  
2021 ◽  
Vol 102 ◽  
Author(s):  
Richard Sima
Keyword(s):  
Climate Change ◽  
Sea Level Rise ◽  
Sea Level ◽  
Sea Levels ◽  
Rising Sea Levels ◽  
Tidal Change

A series of industry posters reimagines iconic locales in light of sea level rise and issues a call for action against climate change.

scholarly journals Unravelling the Importance of Uncertainties in Global-Scale Coastal Flood Risk Assessments under Sea Level Rise

Water ◽  
2021 ◽  
Vol 13 (6) ◽  
pp. 774
Author(s):  
Jeremy Rohmer ◽  
Daniel Lincke ◽  
Jochen Hinkel ◽  
Gonéri Le Cozannet ◽  
Erwin Lambert ◽  
...  
Keyword(s):  
Sea Level Rise ◽  
Sea Level ◽  
Flood Risk ◽  
Global Scale ◽  
Short Term ◽  
Sea Levels ◽  
Coastal Flood ◽  
Extreme Sea Levels ◽  
Coastal Flood Risk ◽  
Adaptation Costs

Global scale assessments of coastal flood damage and adaptation costs under 21st century sea-level rise are associated with a wide range of uncertainties, including those in future projections of socioeconomic development (shared socioeconomic pathways (SSP) scenarios), of greenhouse gas concentrations (RCP scenarios), and of sea-level rise at regional scale (RSLR), as well as structural uncertainties related to the modelling of extreme sea levels, data on exposed population and assets, and the costs of flood damages, etc. This raises the following questions: which sources of uncertainty need to be considered in such assessments and what is the relative importance of each source of uncertainty in the final results? Using the coastal flood module of the Dynamic Interactive Vulnerability Assessment modelling framework, we extensively explore the impact of scenario, data and model uncertainties in a global manner, i.e., by considering a large number (>2000) of simulation results. The influence of the uncertainties on the two risk metrics of expected annual damage (EAD), and adaptation costs (AC) related to coastal protection is assessed at global scale by combining variance-based sensitivity indices with a regression-based machine learning technique. On this basis, we show that the research priorities in terms of future data/knowledge acquisition to reduce uncertainty on EAD and AC differ depending on the considered time horizon. In the short term (before 2040), EAD uncertainty could be significantly decreased by 25 and 75% if the uncertainty of the translation of physical damage into costs and of the modelling of extreme sea levels could respectively be reduced. For AC, it is RSLR that primarily drives short-term uncertainty (with a contribution ~50%). In the longer term (>2050), uncertainty in EAD could be largely reduced by 75% if the SSP scenario could be unambiguously identified. For AC, it is the RCP selection that helps reducing uncertainty (up to 90% by the end of the century). Altogether, the uncertainty in future human activities (SSP and RCP) are the dominant source of the uncertainty in future coastal flood risk.

scholarly journals A National Study on Protecting Infrastructure and Public Buildings against Sea Level Rise and Storm Surge

2021 ◽  
Author(s):  
Paul Chinowsky ◽  
Jacob Helman
Keyword(s):  
Sea Level Rise ◽  
Sea Level ◽  
Storm Surge ◽  
The United States ◽  
Design Guidelines ◽  
National Study ◽  
Multiple Perspectives ◽  
Sea Levels ◽  
Rising Sea Levels ◽  
The Cost

The national study analyzes sea level rise (SLR) impacts based on 36 different SLR and storm surge scenarios across 5.7 million geographic locations and 3 time periods. Taking an approach based on engineering design guidelines and current cost estimates, the study details projected cost impacts for states, counties, and cities. These impacts are presented from multiple perspectives including total cost, cost per-capita, and cost per-square mile. The purpose of the study is to identify specific locations where infrastructure is vulnerable to rising sea levels. The study finds that Sea Level Rise (SLR) and minimal storm surge is a $400 billion threat to the United States by 2040 that includes a need for at least 50,000 miles of protective barriers. The research is limited in its scope to protecting coastal infrastructure with sea walls. Additional methods exist and may be appropriate in individual situations. The study is original in that it is a national effort to identify infrastructure that is vulnerable as well as the cost associated with protecting this infrastructure.

scholarly journals Numerical Modeling of Saltwater Intrusion in the Rmel-Oulad Ogbane Coastal Aquifer (Larache, Morocco) in the Climate Change and Sea-Level Rise Context (2040)

Water ◽  
2021 ◽  
Vol 13 (16) ◽  
pp. 2167
Author(s):  
Mohamed Jalal EL Hamidi ◽  
Abdelkader Larabi ◽  
Mohamed Faouzi
Keyword(s):  
Climate Change ◽  
Sea Level Rise ◽  
Sea Level ◽  
Coastal Aquifer ◽  
Fresh Groundwater ◽  
Sea Levels ◽  
Groundwater Levels ◽  
Rising Sea Levels ◽  
Management Approaches ◽  
And Sea Level

Many coastal aquifers have experienced seawater intrusion (SWI) into fresh groundwater aquifers. The principal causes of SWI include over-pumping and events such as climate change (CC) and rising sea levels. In northern Morocco, the Rmel-Oulad Ogbane coastal aquifer (ROOCA) supplies high-quality groundwater for drinking water and agriculture. This favorable situation has led to increased pumping, resulting in environmental challenges such as dropping water table and SWI. Furthermore, the climate has resulted in less recharge, with an estimated annual precipitation of 602 mm and an average temperature of 18.5 °C. The goal of this study is to determine how CC, over-pumping, and sea-level rise (SLR) affect SWI. Computational groundwater and solute transport models are used to simulate the spatial and temporal evolution of hydraulic heads and groundwater solute concentrations. The calibration is based on steady and transient groundwater levels from 1962 to 2040. SWI simulations show that the NW sector of the coastal area would be polluted, with the toe reaching 5.2 km inland with a significant salinity (15–25 g/L). To protect the fresh water in the reservoir from SWI, enhanced groundwater development and management approaches for this aquifer are required, such as artificial recharge from surface water.

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