scholarly journals Destabilisation and Accelerated Roll-Back of a Mixed Sediment Barrier in Response to a Managed Breach

2021 ◽  
Vol 9 (4) ◽  
pp. 374
Author(s):  
Uwe Dornbusch
Keyword(s):  
Sea Level Rise ◽  
Sea Level ◽  
Medium Term ◽  
Gradual Reduction ◽  
Cross Sectional ◽  
Longshore Transport ◽  
Order Of Magnitude ◽  
Hydrodynamic Data ◽  
Barrier Beaches ◽  
Roll Back

Sea level rise increases the pressure on many coastlines to retreat landwards which will lead to coastlines previously held in position through management, being allowed to retreat where this is no longer affordable or sustainable. Barrier beaches have historically rolled back in response to different hydrodynamic events and sea level rise, but very little is known as to how quickly and how far roll-back is going to occur once management has ceased. Data from more than 40 topographical surveys collected over 7 years along the 1.5 km long, almost swash-aligned shingle barrier at Medmerry (southern England) are used together with hydrodynamic data in a wide-ranging assessment of barrier roll-back. This study shows that roll-back is progressing through time along the barrier in downdrift direction in response to a gradual reduction in cross-sectional area through longshore transport. The Barrier Inertia concept provides a practical means to assess stability/instability for events experienced, but also a tool to assess the short- to medium term risk to the coast downdrift of the immediate study area where flood risk still needs to be managed. Roll-back is influenced particularly by the creation of an artificial tidal breach and removal of its sediment, the elevation of the underlying marsh and clay sediments, the number and severity of storms experienced and the presence of legacy groynes; roll-back has exceeded modelled predictions and expert judgement by an order of magnitude.

Is the Risk of Sea Level Rise Capitalized in Residential Real Estate?

2020 ◽  
Vol 33 (3) ◽  
pp. 1217-1255 ◽  
Author(s):  
Justin Murfin ◽  
Matthew Spiegel
Keyword(s):  
Real Estate ◽  
Sea Level Rise ◽  
Sea Level ◽  
Residential Real Estate ◽  
Cross Sectional ◽  
Null Results ◽  
Expected Time ◽  
Vertical Land Motion ◽  
Price Effects ◽  
Home Sales

Abstract Using a comprehensive database of coastal home sales merged with data on elevation relative to local tides, we compare prices for houses based on their inundation threshold under projections of sea level rise. The analysis separates the sensitivity of housing to rising seas from other confounding characteristics by exploiting cross-sectional differences in relative sea level rise due to vertical land motion. This provides variation in the expected time to inundation for properties of similar elevation and distance from the coast. In a variety of specifications and test settings, we find precisely estimated null results suggesting limited price effects.

scholarly journals Vulnerability Assessment for Sea Level Rise Impacts on Coastal Systems of Gamasa Ras El Bar Area, Nile Delta, Egypt

2021 ◽  
Vol 13 (7) ◽  
pp. 3624
Author(s):  
Ibrahim A. Elshinnawy ◽  
Abdulrazak H. Almaliki
Keyword(s):  
Sea Level Rise ◽  
Sea Level ◽  
Saltwater Intrusion ◽  
Nile Delta ◽  
Drainage System ◽  
Cross Sectional ◽  
Study Objective ◽  
Coastal Systems ◽  
Groundwater Aquifer ◽  
Ras El Bar

The objective of the current study was to assess the vulnerability of coastal systems to sea level rise (SLR) impacts in the Gamasa Ras El Bar area, which is one of the most vulnerable coastal areas in the Nile delta, Egypt. To achieve the study objective, a field campaign was carried out to investigate, measure and collect data. These data, as well as historical data, were analyzed to identify projected inundation areas, erosion and accretion rates, shoreline changes, wave climate and saltwater intrusion, as well as drainage infrastructure efficiency. The results of a 73-cm SLR, projected up to the end of current century in the study area, indicate the following. Inundation areas will be about 2.16% of the study area. Although the significant wave height increased by 3.1 cm per year from 1999 to 2010, the results are indicative and might be taken into consideration in future coastal management plans. The expected variation in groundwater heads due to sea level rise will lead to an increase in groundwater heads ranging from 0 to 0.5 m above the current level. The change expected in groundwater will lead to saltwater intrusion by 1 km landward. The analysis of our results showed that about 271 km2 (60%) of the area under study will be negatively affected by rising groundwater. This area is occupied by about 70% of the localities in the study area. The analysis of the projected groundwater level rise showed that it will increase the discharges of the sub-drainage system by about 10% of the current rates and less than 1.2% for the open system. It is concluded that the drainage system has the sub-capacity to host the expected increase in drainage discharges without any modifications of the cross-sectional area of most of the drains. In addition, the coastal groundwater aquifer was found to be the most vulnerable system in the study area.

scholarly journals Exploration of Antarctic Ice Sheet 100-year contribution to sea level rise and associated model uncertainties using the ISSM framework

2018 ◽  
Author(s):  
Nicole-Jeanne Schlegel ◽  
Helene Seroussi ◽  
Michael P. Schodlok ◽  
Eric Y. Larour ◽  
Carmen Boening ◽  
...  
Keyword(s):  
Sea Level Rise ◽  
Sea Level ◽  
Ice Sheet ◽  
Snow Accumulation ◽  
Ice Shelf ◽  
Amundsen Sea ◽  
Antarctic Ice Sheet ◽  
Future Evolution ◽  
Continental Scale ◽  
Order Of Magnitude

Abstract. Estimating the future evolution of the Antarctic Ice Sheet (AIS) is critical for improving future sea level rise (SLR) projections. Numerical ice sheet models are invaluable tools for bounding Antarctic vulnerability; yet, few continental scale projections of century-scale AIS SLR contribution exist, and those that do vary by up to an order of magnitude. This is partly because model projections of future sea level are inherently uncertain and depend largely on the model's boundary conditions and climate forcing. Here, we aim to improve the understanding of how such uncertainties affect ice sheet model simulations. With use of Monte-Carlo style uncertainty quantification techniques embedded within the Ice Sheet System Model (ISSM) framework, we assess how uncertainties in snow accumulation, ocean induced melting, ice viscosity, basal friction, bedrock elevation, and the presence of ice shelves, impact continental scale 100-year projections of AIS sea level contribution. Overall, we find that AIS sea level contribution is strongly affected by grounding line retreat, which is driven by the magnitude of ice shelf basal melt rates and by errors in bedrock topography. In addition, we find that over 1.2 meters of AIS global mean sea level contribution over the next century is achievable, but not likely, as it is tenable only in response to unrealistically large melt rates and instantaneous continental ice shelf collapse. Regionally, we find that under an endmember 100-year warming scenario generalized for the entire ice sheet, the Amundsen Sea Sector is the most significant source of model uncertainty (1032 mm 6σ spread). This region also has the largest potential for future sea level contribution (297 mm). In contrast, under a more plausible scenario informed regionally by literature and model sensitivity studies, the Ronne basin has a greater potential for local increases in ice shelf basal melt rates. As a result, under this more likely scenario where warm waters reach the continental shelf under the Ronne ice shelf, it is the Ronne basin, particularly the Evans and Rutford Ice Streams, that are the greatest contributors to potential SLR (161 mm) and to simulation uncertainty (420 mm 6σ spread).

scholarly journals Geometrical Analysis of the Inland Topography to Assess the Likely Response of Wave-Dominated Coastline to Sea Level: Application to Great Britain

2020 ◽  
Vol 8 (11) ◽  
pp. 866
Author(s):  
Andres Payo ◽  
Chris Williams ◽  
Rowan Vernon ◽  
Andrew G. Hulbert ◽  
Kathryn A. Lee ◽  
...  
Keyword(s):  
Great Britain ◽  
Sea Level Rise ◽  
Sea Level ◽  
Emission Scenario ◽  
Response Rate ◽  
Rate Of Change ◽  
Geometrical Analysis ◽  
Special Report ◽  
Large Spatial Scale ◽  
Barrier Beaches

The need for quantitative assessments at a large spatial scale (103 km) and over time horizons of the order 101 to 102 years have been reinforced by the 2019 Special Report on the Ocean and Cryosphere in a Changing Climate, which concluded that adaptation to a sea-level rise will be needed no matter what emission scenario is followed. Here, we used a simple geometrical analysis of the backshore topography to assess the likely response of any wave-dominated coastline to a sea-level rise, and we applied it along the entire Great Britain (GB) coastline, which is ca. 17,820 km long. We illustrated how the backshore geometry can be linked to the shoreline response (rate of change and net response: erosion or accretion) to a sea-level rise by using a generalized shoreline Exner equation, which includes the effect of the backshore slope and differences in sediment fractions within the nearshore. To apply this to the whole of GB, we developed an automated delineation approach to extract the main geometrical attributes. Our analysis suggests that 71% of the coast of GB is best described as gentle coast, including estuarine coastline or open coasts where back-barrier beaches can form. The remaining 39% is best described as cliff-type coastlines, for which the majority (57%) of the backshore slope values are negative, suggesting that a non-equilibrium trajectory will most likely be followed as a response to a rise in sea level. For the remaining 43% of the cliffed coast, we have provided regional statistics showing where the potential sinks and sources of sediment are likely to be.

scholarly journals Brief communication "Global glacier volumes and sea level – small but systematic effects of ice below the surface of the ocean and of new local lakes on land"

2013 ◽  
Vol 7 (3) ◽  
pp. 817-821 ◽  
Author(s):  
W. Haeberli ◽  
A. Linsbauer
Keyword(s):  
Sea Level Rise ◽  
Sea Level ◽  
Magnitude Estimate ◽  
Potential Contribution ◽  
Present Communication ◽  
First Order ◽  
Ice Caps ◽  
Ice Volume ◽  
Systematic Effects ◽  
Order Of Magnitude

Abstract. The potential contribution of glaciers and ice caps to sea level rise is usually calculated by comparing the estimated total ice volume with the surface area of the ocean. Part of this total ice volume, however, does not contribute to sea level rise because it is below the surface of the ocean or below the levels of future lakes on land. The present communication points to this so far overlooked phenomenon and provides a first order-of-magnitude estimate. It is shown that the effect is small (most likely about 1 to 6 cm sea level equivalent) but systematic, could primarily affect earlier stages of global glacier vanishing, and should therefore be adequately considered. Now-available techniques of slope-related high-resolution glacier bed modelling have the potential to provide more detailed assessments in the future.

The fate of beach nourishment sand placed on the Florida East Coast

Shore & Beach ◽  
2019 ◽  
pp. 3-14 ◽  
Author(s):  
James Houston
Keyword(s):  
Sea Level Rise ◽  
Sea Level ◽  
East Coast ◽  
Beach Nourishment ◽  
Shoreline Change ◽  
Storm Damage ◽  
Intergovernmental Panel ◽  
Longshore Transport ◽  
Beach Width ◽  
Equilibrium Profile

Over 100 million yd3 of sand have been placed on Florida east coast beaches since the start of widespread beach nourishment in 1970. What has been the fate of this sand? Has it largely disappeared as some suggest, or is it largely in place, having increased beach width as much as expected? Shoreline position measurements show that beach nourishment has dominated shoreline change with beaches widening over 80 ft on average since 1970. Nourished beaches have widened an average of almost 120 ft and adjacent beaches that have never been nourished have widened almost 50 ft due to longshore transport moving nourishment sand to them. Using equilibrium profile theory, shoreline advance due to beach nourishment minus shoreline recession caused by longshore transport, inlets that trap sand in shoals, and sea level rise is shown to equal measured shoreline change within uncertainty limits in each east coast Florida county and for the entire coastline. About 90% of beach nourishment sand remains on profiles in the active littoral zone. Shoreline advance produced by beach nourishment has been eight times greater than the magnitude of the recession caused by sea level rise from 1970-2017. If beach nourishment sand is placed along this coast at the rate of the past 40 years, the shoreline will be wider in 2100 than in 2018 for all sea-levelrise scenarios of the Intergovernmental Panel on Climate Change (IPCC). Increased beach width since 1970 has produced significant benefits by reducing infrastructure storm damage and greatly increasing beach tourism.

scholarly journals Sensitivity of tidal motion in well-mixed estuaries to cross-sectional shape, deepening, and sea level rise

2015 ◽  
Vol 65 (7) ◽  
pp. 933-950 ◽  
Author(s):  
Erik Ensing ◽  
Huib E. de Swart ◽  
Henk M. Schuttelaars
Keyword(s):  
Sea Level Rise ◽  
Sea Level ◽  
Cross Sectional ◽  
Tidal Motion ◽  
Sectional Shape ◽  
And Sea Level

scholarly journals Global glacier volumes and sea level – effects of ice below the surface of the ocean and of new local lakes on land

2012 ◽  
Vol 6 (6) ◽  
pp. 5169-5179
Author(s):  
W. Haeberli ◽  
A. Linsbauer
Keyword(s):  
High Resolution ◽  
Sea Level Rise ◽  
Sea Level ◽  
Magnitude Estimate ◽  
Potential Contribution ◽  
Present Communication ◽  
First Order ◽  
Ice Caps ◽  
Ice Volume ◽  
Order Of Magnitude

Abstract. The potential contribution of glaciers and ice caps to sea level rise is usually calculated by comparing the estimated total ice volume with the surface area of the ocean. Part of this total ice volume, however, does not contribute to sea-level rise, because it is below the surface of the ocean or below the levels of future lakes on land. The present communication points to this so far overlooked phenomenon and provides a first order-of-magnitude estimate. It is shown that the effect is small (most likely 1 to 5 cm sea-level equivalent) but systematic, could primarily affect earlier stages of global glacier vanishing and should therefore be adequately considered. Now-available techniques of slope-related high-resolution glacier-bed modelling have the potential to provide more detailed assessments in the future.

The uncertain future of the Antarctic Ice Sheet

Science ◽  
2020 ◽  
Vol 367 (6484) ◽  
pp. 1331-1335 ◽  
Author(s):  
Frank Pattyn ◽  
Mathieu Morlighem
Keyword(s):  
Sea Level Rise ◽  
Sea Level ◽  
Time Scales ◽  
Temperature Increase ◽  
Ice Sheet ◽  
Antarctic Ice Sheet ◽  
Positive Feedbacks ◽  
Order Of Magnitude ◽  
Uncertain Future ◽  
The Antarctic

The Antarctic Ice Sheet is losing mass at an accelerating pace, and ice loss will likely continue over the coming decades and centuries. Some regions of the ice sheet may reach a tipping point, potentially leading to rates of sea level rise at least an order of magnitude larger than those observed now, owing to strong positive feedbacks in the ice-climate system. How fast and how much Antarctica will contribute to sea level remains uncertain, but multimeter sea level rise is likely for a mean global temperature increase of around 2°C above preindustrial levels on multicentennial time scales, or sooner for unmitigated scenarios.

Targeted Glacial Geoengineering through Seabed Anchored Curtains

2020 ◽  
Author(s):  
Michael Wolovick ◽  
John Moore ◽  
Rajeev Jaiman ◽  
Jasmin Jelovica ◽  
Bowie Keefer
Keyword(s):  
Sea Level Rise ◽  
Sea Level ◽  
Tensile Load ◽  
Warm Water ◽  
Coastal Protection ◽  
Ice Streams ◽  
Central Trough ◽  
Water Blocking ◽  
Order Of Magnitude ◽  
Static Tensile

<p>Rapid sea level rise due to an ice sheet collapse has the potential to be extremely damaging to coastal communities and infrastructure, and conventional coastal protection techniques (dykes, levees, etc) can be quite expensive. In the past we have proposed that society might employ artificial sills and pinning points at critical marine ice streams in Antarctica to slow the rate of sea level rise at the source (Wolovick and Moore, 2018). However, thick earthen sills are likely to be extremely expensive and difficult to construct. If the goal of the intervention is only to block warm water from reaching the grounding line, then an alternate intervention consisting of thin flexible buoyant curtains anchored to the seabed might be employed instead. Flexible curtains are likely to be cheaper, more robust against iceberg collisions, and easier to remove in the event of unforeseen side effects. Here, we use a simple ice flow model to evaluate the effectiveness of such an intervention at three important Greenlandic outlet glaciers, and we make crude estimates of the forces on the curtain and of the likely cost of construction. We find that the single most important factor controlling the effectiveness of a thin water-blocking intervention (defined as either slowing glacier retreat or causing readvance) is the exposure of the glacier to deep warm water at the time of barrier construction. This means that, for Jakobshavn Isbrae, which has a deep (~1000 m) central trough extending well over 100 km inland, a water-blocking intervention is likely to be effective far into the future, and also that the preventable retreat (in comparison to a no-intervention scenario) is quite large. For Helheim and Kangerdlugssuaq, however, the central trough rises rapidly just a few tens of kilometers inland of the present-day calving front, removing the vulnerability to deep warm water after a relatively small retreat. This means both that the intervention must be begun relatively soon if it is to have an effect at those glaciers, and that the preventable retreat is smaller. With respect to the forces acting on the curtain, we find that the static tensile load on the curtain rises quadratically with the height above the seabed, and linearly with respect to the density contrast between the inner waters and the outer waters. Since the natural sills at the fjord mouths are roughly three times deeper at Helheim and Kangerdlugssuaq than they are at Jakobshavn, curtains at the former would need to be roughly an order of magnitude stronger than curtains at the latter. We estimate that this translates into roughly five times greater cost (per unit barrier length) at the two East Greenland glaciers than at Jakobshavn. Therefore, based on both cost and effectiveness, we find that this type of intervention is more favored for Jakobshavn than it is for Helheim and Kangerdlugssuuaq.</p>

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