scholarly journals Single Extreme Strong Sequence Can Offset Decades of Shoreline Retreat by Sea-level Rise

2021 ◽  
Author(s):  
Mitchell Harley ◽  
Gerd Masselink ◽  
Amaia Ruiz de Alegría-Arzaburu ◽  
Nieves Valiente ◽  
Tim Scott
Keyword(s):  
Sea Level Rise ◽  
Sea Level ◽  
Coastal Erosion ◽  
Sediment Budget ◽  
Positive Contribution ◽  
Volume Changes ◽  
Shoreline Retreat ◽  
Quantitative Understanding ◽  
The Uk

Abstract Extreme storms cause extensive beach-dune erosion and are universally considered to enhance coastal erosion due to sea-level rise (SLR). However, extreme storms can also have a positive contribution to the nearshore sediment budget by exchanging sediment between the lower and upper shoreface and/or between adjacent headlands, potentially mitigating adverse SLR impacts. Here we use three high-resolution morphological datasets of extreme storm-recovery sequences from Australia, the UK and Mexico to quantify the nearshore sediment budget and relate these episodic volume changes to long-term coastal forecasts. We show that sediment gains over the upper shoreface and beach were very significant (58-140 m3/m) and sufficient to offset decades of predicted shoreline retreat due to SLR, even for an upper SSP5-8.5 scenario. It is evident that increased confidence in shoreline predictions due to SLR relies fundamentally on robust quantitative understanding of the sediment budget, in particular any long-term contribution of sediment transport from outside the nearshore region.

scholarly journals IMMERSIVE EXPERIENCES IN CLIMATE ADAPTATION

2020 ◽  
pp. 10
Author(s):  
Juliano Calil
Keyword(s):  
Sea Level Rise ◽  
Sea Level ◽  
Coastal Erosion ◽  
Climate Adaptation ◽  
3D Models ◽  
Coastal Communities ◽  
Long Beach ◽  
Coastal Risks ◽  
Impacts Of Climate Change

As coastal communities worldwide contend with sea-level rise, coastal erosion, and other impacts of climate change, a critical piece of the puzzle has become educating stakeholders in highly creative, insightful, and practical ways. In this study, we will highlight the main findings from the use of immersive and interactive Virtual Reality (VR) experiences in climate adaptation. These tools are helping coastal communities better understand potential impacts as well as explore near- and long-term solutions to reduce coastal risks. We will describe the challenges and steps taken to develop these applications at four coastal locations in the U.S. (Turner Station, MD, and Santa Cruz, Long Beach, and Moss Landing in CA); from identifying key objectives of each experience, the critical messages, and target audiences, to flying drones over coastal areas and working with photogrammetry to create hyper-realistic 3D models that are inserted in the VR experience. These immersive and interactive experiences support planning, management and monitoring activities related to sea-level rise, storms, coastal erosion, king tides, and more. These tools are being developed by a multidisciplinary team with a range of expertise including climate and coastal scientists, city planners, communications experts, filmmakers, 3D animators, and VR developers.Recorded Presentation from the vICCE (YouTube Link): https://youtu.be/aDIkbn_FO1c

scholarly journals Deconvolving The Effects of Coastal Erosion and Sea-Level Rise in Assessing Shoreline Retreat Along Semi-Arid Urban Coasts

2022 ◽  
Author(s):  
Oula Amrouni ◽  
Essam Heggy ◽  
Abderraouf Hzami
Keyword(s):  
Land Use ◽  
Sea Level Rise ◽  
Sea Level ◽  
Urban Growth ◽  
Urban Areas ◽  
Coastal Erosion ◽  
Sandy Beaches ◽  
Coastal Areas ◽  
Shoreline Retreat ◽  
Semi Arid

Abstract The alarming vulnerability of low-lying sandy beaches to the acceleration of global sea level rise has been confirmed in the recent IPCC AR6 report. The situation is worsened by increasing coastal erosion, resulting in additional shoreline retreat of sandy beaches along several semi-arid urban coastal areas around the globe. The additional shoreline retreats from erosion are indicative of the rising imbalance in coastal sedimentary processes, which are a direct consequence of changes in precipitation patterns, urban growth, and change in land use. To quantify the magnitude and timescale of both coastal erosion and sea-level rise (SLR) in generating shoreline retreat of sandy beaches in semi-arid urban areas, we combine photogrammetric and statistical methods to measure and forecast the decadal evolution of these coastlines using two well-characterized sites that are hypothesized herein to be globally representative of these types of coasts undergoing rapid urban growth. We use multi-decadal shoreline positioning and land use classification surveys of the Southern California (SC, USA) and the Hammamet-North (HAM, Tunisia) beaches from aerial and orbital photogrammetric images, combined with the Digital Shoreline Analysis System, for the period from 1985 to 2018. Our results suggest that the current average shoreline retreat rates of sandy beaches range from -0.75 to -1.24 m/yr in SC and from -0.21 to -4.49 m/yr in HAM under similar aridity, land coverage and precipitation patterns. The observed decadal changes in shoreline positions along these semi-arid urban coastal areas are found to be accentuated by anthropogenic drivers associated with extensive urbanization, causing sediment imbalance at the coastline, adding up to the effect of the accelerating SLR. We assess that ~81% and 57% of the observed shoreline retreat was due to SLR, and 19% to 43% due to coastal erosion from urban growth along SC and HAM beaches, respectively. Using these measured rates, we establish a semi-empirical numerical model that combines urban growth and the observed shoreline retreat rate to forecast retreat rates through 2100 for both of our study areas, inferred herein to be representative of other global semi-arid urban coasts. Our model suggests that future average total shoreline retreat rates, accounting for both urban growth and SLR, range from -2 to -4 m/yr for SC and HAM sandy beaches, respectively, through 2100. The above suggests that if no mitigation is made, by 2100 the cumulative shoreline retreat in these urban areas could significantly exceed the Global Scale Assessment Model’s [46] cumulative projected average retreat of -30 m, confirming the alarming vulnerability of the semi-arid coastal urban areas that would need intensive and costly beach nourishment to control increasing shoreline erosion.

An Assessment of the Radiological Impact of Coastal Erosion of the UK Low-Level Waste Repository

2011 ◽  
Author(s):  
Trevor Sumerling ◽  
Paul Fish ◽  
George Towler ◽  
James Penfold ◽  
John Shevelan ◽  
...  
Keyword(s):  
Sea Level Rise ◽  
Sea Level ◽  
Coastal Erosion ◽  
Assessment Model ◽  
Coastal System ◽  
Future Evolution ◽  
Low Level ◽  
Waste Repository ◽  
The Uk ◽  
The Impact

The UK Low Level Waste Repository Ltd submitted an Environmental Safety Case for the disposal of low-level waste to our regulator, the Environment Agency, on the 1st of May 2011. This includes assessments of the long-term radiological safety of past and future disposals. A particular feature of the Low Level Waste Repository (LLWR) is that, because of its proximity to the coast, the site is vulnerable to coastal erosion. Our present understanding is that the site will be eroded on a timescale of a few hundred to a few thousand years, with consequent disruption of the repository, and dispersal of the wastes. We have undertaken a programme of scientific research and monitoring to characterise the evolution and function of the current coastal system that provides a basis for forecasting its future evolution. This has included modelling of contemporary hydrodynamics, geomorphological mapping, repeat LiDAR and aerial photographic surveys to detect patterns and rates of change, coastal inspections and reconstructions of post-glacial (i.e. last 15,000 years) sea levels and sediment budgets. Estimates of future sea-level rise have been derived from international sources and consideration given to the impact of such on the local coastline. Two alternative models of coastal recession have then been applied, one empirical and one physical-process based, taking account of the composition of Quaternary-age sediments between the coast and the site and uncertainties in future local sea level change. Comparison of the ranges of calculated times to site contact with sea-level rise indicate that the repository is most likely to be disrupted by undercutting of the engineered vaults and of the trenches. A novel and flexible radiological assessment model has been developed to analyse the impacts of the erosion of the repository and subsequent dispersal of wastes. The model represents the spatial layout of the site and distribution of radionuclides within the repository and is able to take account of a range of uncertainties. These include uncertainties related to the rate of erosion through the facility, amounts of co-erosion of geological and cap materials, alternative assumptions for residence of waste materials on the beach, alternative waste form associations, the wider dispersion of the eroded materials and marine sorption/desorption processes. Results indicate assessed annual doses and risks that are consistent with regulatory guidance levels.

scholarly journals A Holistic Framework for Evaluating Adaptation Approaches to Coastal Hazards and Sea Level Rise: A Case Study from Imperial Beach, California

Water ◽  
2021 ◽  
Vol 13 (9) ◽  
pp. 1324
Author(s):  
David Revell ◽  
Phil King ◽  
Jeff Giliam ◽  
Juliano Calil ◽  
Sarah Jenkins ◽  
...  
Keyword(s):  
Sea Level Rise ◽  
Sea Level ◽  
Public Trust ◽  
Adaptation Strategy ◽  
Public Benefits ◽  
Study Results ◽  
Local Risk ◽  
Over Time

Sea level rise increases community risks from erosion, wave flooding, and tides. Current management typically protects existing development and infrastructure with coastal armoring. These practices ignore long-term impacts to public trust coastal recreation and natural ecosystems. This adaptation framework models physical responses to the public beach and private upland for each adaptation strategy over time, linking physical changes in widths to damages, economic costs, and benefits from beach recreation and nature using low-lying Imperial Beach, California, as a case study. Available coastal hazard models identified community vulnerabilities, and local risk communication engagement prioritized five adaptation approaches—armoring, nourishment, living shorelines, groins, and managed retreat. This framework innovates using replacement cost as a proxy for ecosystem services normally not valued and examines a managed retreat policy approach using a public buyout and rent-back option. Specific methods and economic values used in the analysis need more research and innovation, but the framework provides a scalable methodology to guide coastal adaptation planning everywhere. Case study results suggest that coastal armoring provides the least public benefits over time. Living shoreline approaches show greater public benefits, while managed retreat, implemented sooner, provides the best long-term adaptation strategy to protect community identity and public trust resources.

Long-term legacy of delayed climate mitigation in global glacier response

2021 ◽  
Author(s):  
Fabien Maussion ◽  
Quentin Lejeune ◽  
Ben Marzeion ◽  
Matthias Mengel ◽  
David Rounce ◽  
...  
Keyword(s):  
Sea Level Rise ◽  
Greenhouse Gas ◽  
Sea Level ◽  
Climate Mitigation ◽  
Delayed Response ◽  
Glacier Change ◽  
Mountain Glaciers ◽  
Glacier Runoff ◽  
The Impact

<p>Mountain glaciers have a delayed response to climate change and are expected to continue to melt long after greenhouse gas emissions have stopped, with consequences both for sea-level rise and water resources. In this contribution, we use the Open Global Glacier Model (OGGM) to compute global glacier volume and runoff changes until the year 2300 under a suite of stylized greenhouse gas emission characterized by (i) the year at which anthropogenic emissions culminate, (ii) their reduction rates after peak emissions and (iii) whether they lead to a long-term global temperature stabilization or decline. We show that even under scenarios that achieve the Paris Agreement goal of holding global-mean temperature below 2 °C, glacier contribution to sea-level rise will continue well beyond 2100. Because of this delayed response, the year of peak emissions (i.e. the timing of mitigation action) has a stronger influence on mit-term global glacier change than other emission scenario characteristics, while long-term change is dependent on all factors. We also discuss the impact of early climate mitigation on regional glacier change and the consequences for glacier runoff, both short-term (where some basins are expected to experience an increase of glacier runoff) and long-term (where all regions are expecting a net-zero or even negative glacier contribution to total runoff), underlining the importance of mountain glaciers for regional water availability at all timescales.</p>

Influence of ground ice and permafrost on coastal evolution, Richards Island, Beaufort Sea coast, N.W.T.

1996 ◽  
Vol 33 (5) ◽  
pp. 664-675 ◽  
Author(s):  
Scott R. Dallimore ◽  
Stephen A. Wolfe ◽  
Steven M. Solomon
Keyword(s):  
Coastal Erosion ◽  
Sediment Budget ◽  
Storm Event ◽  
Ground Ice ◽  
Coastal Evolution ◽  
Thermal Erosion ◽  
Ice Wedge ◽  
Mechanical Erosion ◽  
Sea Coast

A long-term sediment budget (1947−1985) for northern Richards Island shows that, when ground ice and offshore erosion are accounted for, there is a near balance between headland erosion and coastal deposition. Excess ice constitutes about 20% of the total volume of eroded material from the headlands, with massive ground ice contributing nearly 9% and segregated ice lenses and ice wedges making up the remainder. Coastal response to major storms in 1987 and 1993 suggests that erosion is episodic, with short periods of intense disruption followed by readjustment of cliff profiles. Processes characteristic of this environment include mechanical erosion of ice-bonded sediments creating unstable erosional niches, mechanical failure of niches along ice-wedge planes, and longer term thermal erosion of ice-bonded sediments. Where ice contents are high, localized thaw slumps initiated by coastal erosion may retreat at rates substantially higher than those observed at other sections of the coast. Cliff-top retreat rates may be out of phase with storm-event chronology.

scholarly journals Implementing Pre-Emptive Managed Retreat: Constraints and Novel Insights

2021 ◽  
Author(s):  
Judith Lawrence ◽  
Jonathan Boston ◽  
R Bell ◽  
S Olufson ◽  
R Kool ◽  
...  
Keyword(s):  
Sea Level Rise ◽  
Sea Level ◽  
First Century ◽  
Current State ◽  
Adaptation Response ◽  
Extreme Flooding ◽  
Protective Structures ◽  
Implementation Gaps ◽  
Post Disaster

Purpose of Review: Managed retreat will be inevitable where other adaptation options, such as protective structures or building restrictions, provide only temporary respite or are otherwise uneconomic, technically impractical or both. Here, we focus on the implementation of pre-emptive managed retreat, providing examples of how it can be sequenced, socialised and given the governance enablers necessary for implementation. Recent Findings: Ongoing sea-level rise during the twenty-first century and beyond poses huge adaptation challenges, especially for low-lying coastal and floodplain settlements. Settlements are already functionally disrupted from repetitive non-extreme flooding and research shows that sea-level rise will impact far more people, far sooner than previously thought, as more powerful storms, heavy rainfall and rising groundwater coincide with higher tides. To date, most examples of managed retreat have been post-disaster responses following damage and disruption. Pre-emptive managed retreat, by contrast, has yet to become a well-accepted and widely practised adaptation response. Nevertheless, there are increasing examples of research and practice on how pre-emptive managed retreat can be designed, sequenced and implemented alongside other forms of adaptation within anticipatory forms of governance. Summary: The current state of knowledge about managed retreat is reviewed and critical insights and lessons for governance and policy-making are given. Several novel examples from New Zealand are presented to address some of the implementation gaps. Goals and principles are enunciated to inform long-term adaptation strategies.

scholarly journals Supplemental Material: Detrital signals of coastal erosion and fluvial sediment supply during glacio-eustatic sea-level rise, Southern California, USA

2021 ◽  
Author(s):  
Glenn Sharman ◽  
et al.
Keyword(s):  
Sea Level Rise ◽  
Sea Level ◽  
Coastal Erosion ◽  
Southern California ◽  
Mixture Modeling ◽  
Sediment Supply ◽  
Analytical Methodology ◽  
Fluvial Sediment ◽  
Icp Ms ◽  
Data Tables

Sample summary, LA-ICP-MS data tables, sources of Cretaceous-Paleogene forearc data, Peninsular Ranges batholith zircon U-Pb ages, mixture modeling results, and U-Pb analytical methodology.<br>

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