scholarly journals Assessment of island beach erosion due to sea level rise: the case of the Aegean archipelago (Eastern Mediterranean)

2017 ◽  
Vol 17 (3) ◽  
pp. 449-466 ◽  
Author(s):  
Isavela N. Monioudi ◽  
Adonis F. Velegrakis ◽  
Antonis E. Chatzipavlis ◽  
Anastasios Rigos ◽  
Theophanis Karambas ◽  
...  
Keyword(s):  
Sea Level Rise ◽  
Sea Level ◽  
Spatial Information ◽  
Eastern Mediterranean ◽  
Sediment Supply ◽  
Coastal Development ◽  
Beach Erosion ◽  
Coastal Protection ◽  
Intergovernmental Panel ◽  
Economic Resource

Abstract. The present contribution constitutes the first comprehensive attempt to (a) record the spatial characteristics of the beaches of the Aegean archipelago (Greece), a critical resource for both the local and national economy, and (b) provide a rapid assessment of the impacts of the long-term and episodic sea level rise (SLR) under different scenarios. Spatial information and other attributes (e.g., presence of coastal protection works and backshore development) of the beaches of the 58 largest islands of the archipelago were obtained on the basis of remote-sensed images available on the web. Ranges of SLR-induced beach retreats under different morphological, sedimentological and hydrodynamic forcing, and SLR scenarios were estimated using suitable ensembles of cross-shore (1-D) morphodynamic models. These ranges, combined with empirically derived estimations of wave run-up induced flooding, were then compared with the recorded maximum beach widths to provide ranges of retreat/erosion and flooding at the archipelago scale. The spatial information shows that the Aegean pocket beaches may be particularly vulnerable to mean sea level rise (MSLR) and episodic SLRs due to (i) their narrow widths (about 59 % of the beaches have maximum widths < 20 m), (ii) their limited terrestrial sediment supply, (iii) the substantial coastal development and (iv) the limited existing coastal protection. Modeling results indeed project severe impacts under mean and episodic SLRs, which by 2100 could be devastating. For example, under MSLR of 0.5 m – representative concentration pathway (RCP) 4.5 of the Fifth Assessment Report (AR5) of the Intergovernmental Panel on Climate change (IPCC) – a storm-induced sea level rise of 0.6 m is projected to result in a complete erosion of between 31 and 88 % of all beaches (29–87 % of beaches are currently fronting coastal infrastructure and assets), at least temporarily. Our results suggest a very considerable risk which will require significant effort, financial resources and policies/regulation in order to protect/maintain the critical economic resource of the Aegean archipelago.

scholarly journals Assessment of island beach erosion due to sea level rise: The case of the Aegean Archipelago (Eastern Mediterranean)

2016 ◽  
Author(s):  
Isavela N. Monioudi ◽  
Adonis F. Velegrakis ◽  
Antonis E. Chatzipavlis ◽  
Anastasios Rigos ◽  
Theophanis Karambas ◽  
...  
Keyword(s):  
Sea Level Rise ◽  
Sea Level ◽  
Spatial Information ◽  
Eastern Mediterranean ◽  
Rapid Assessment ◽  
Beach Erosion ◽  
Coastal Protection ◽  
Present Contribution ◽  
Critical Resource ◽  
Run Up

Abstract. The present contribution constitutes the first comprehensive attempt to (a) record the spatial characteristics of the beaches of the Aegean Archipelago (Greece), a critical resource for both the local and national economy; and (b) provide a rapid assessment of the impacts of the long-term and episodic sea level rise (SLR), under different scenarios. Spatial information and other attributes (e.g. presence of coastal protection works and backshore development) of the beaches of the 58 largest islands of the Archipelago were obtained on the basis of remote-sensed images available in the web. Ranges of SLR-induced beach retreats under different morphological, sedimentological and hydrodynamic forcing and SLR scenarios were estimated, using suitable ensembles of cross-shore (1-D) morphodynamic models. These ranges, combined with empirically-derived estimations of wave run up-induced flooding, were then compared with the recorded maximum beach widths, to provide ranges of retreat/erosion and flooding at the Archipelago scale. The spatial information shows that the Aegean beaches may be particularly vulnerable to mean (MSLR) and episodic SLRs due to: (i) their narrow widths (about 59 % of the beaches have maximum widths

Integrating biogeomorphic feedbacks in the coastal zone to bolster coastal resiliency

2021 ◽  
Author(s):  
Cindy Palinkas ◽  
Lorie Staver
Keyword(s):  
Sea Level Rise ◽  
Sea Level ◽  
Management Strategy ◽  
Environmental Changes ◽  
Sediment Supply ◽  
Coastal Protection ◽  
Coastal System ◽  
Living Shorelines ◽  
Accretion Rates ◽  
Created Marshes

&lt;p&gt;Living shorelines, defined in this study as narrow marsh fringes with adjacent sills, have been gaining traction as the preferred management strategy to mitigate shoreline erosion. These nature-based features provide the same ecosystem services as natural marshes while protecting coastlines. However, they also are threatened by the same environmental changes (sea-level rise, changing sediment supply) as natural marshes and may change characteristics of adjacent subtidal sediments. This study evaluates the role of plants in both the created marshes of living shorelines and, where present, beds of submersed aquatic vegetation (SAV) in the adjacent subtidal in the effectiveness, impacts, and resiliency of living shorelines over ~10 years in mesohaline Chesapeake Bay. At study sites, there is a net seaward movement of shorelines with living shoreline installation due to construction technique. This movement replaces shallow-water habitat immediately adjacent to the pre-existing shoreline; farther offshore, sedimentological changes vary among sites but do not appear to drive changes in the presence/absence of subtidal SAV. While current accretion rates in the created marshes are greater than local relative sea-level rise, there is evidence that accretion rates increase with marsh age, suggesting that living shorelines are most vulnerable in the first few years after installation. Because nutrient burial is maximized when SAV occur next to living shorelines, a management strategy that considers the subtidal and intertidal as integrated components of the coastal system is needed to optimize co-benefits of coastal protection.&lt;/p&gt;

scholarly journals The Potential Role of Artificial Marsh on Coastal Protection in Long Island Sound

2020 ◽  
Author(s):  
Amin Ilia
Keyword(s):  
Sea Level Rise ◽  
Sea Level ◽  
Wave Energy ◽  
Salt Marshes ◽  
Hurricane Sandy ◽  
Sediment Supply ◽  
Coastal Protection ◽  
Climate Change Effects ◽  
Data Assessment ◽  
Accretion Rates

Connecticut marshes, like other marshes in the world, are vulnerable to anthropogenic and climate change effects. However, assessment of current sea level rise and average marsh accretion rates in Connecticut demonstrate sea level rise is not the main vulnerable factor for salt marshes loss. The study on the feasibility of developing an ecosystem-based on two coastlines in Connecticut, Guilford and Stratford, shows that both coastlines, like other coastlines in Connecticut, have limited wave energy, which is a positive factor for marsh growth. The available data assessment represents that sediment supply is the most important parameter to guarantee the resilience and sustainability of a newly developed salt marsh system in Connecticut. In Stratford, conditions for establishing a new ecosystem seem to be better, as the fetch length is pretty small, and there is some sediment supply for the ecosystem. In Guilford, wave energy is limited, but it is more than in Stratford case. Besides, sediment availability is low and the coastline experienced considerable erosion during hurricane Sandy and has not recovered yet.

scholarly journals Success of coastal wetlands restoration is driven by sediment availability

2021 ◽  
Vol 2 (1) ◽  
Author(s):  
Zezheng Liu ◽  
Sergio Fagherazzi ◽  
Baoshan Cui
Keyword(s):  
Sea Level Rise ◽  
Sea Level ◽  
Coastal Wetlands ◽  
Coastal Wetland ◽  
Meta Analysis ◽  
Regional Scale ◽  
Global Strategy ◽  
Sediment Supply ◽  
Tidal Range ◽  
Coastal Protection

AbstractShorelines and their ecosystems are endangered by sea-level rise. Nature-based coastal protection is becoming a global strategy to enhance coastal resilience through the cost-effective creation, restoration and sustainable use of coastal wetlands. However, the resilience to sea-level rise of coastal wetlands created under Nature-based Solution has been assessed largely on a regional scale. Here we assess, using a meta-analysis, the difference in accretion, elevation, and sediment deposition rates between natural and restored coastal wetlands across the world. Our results show that restored coastal wetlands can trap more sediment and that the effectiveness of these restoration projects is primarily driven by sediment availability, not by wetland elevation, tidal range, local rates of sea-level rise, and significant wave height. Our results suggest that Nature-based Solutions can mitigate coastal wetland vulnerability to sea-level rise, but are effective only in coastal locations where abundant sediment supply is available.

scholarly journals Coastal Structures as Beach Erosion Control and Sea Level Rise Adaptation in Malaysia: A Review

Water ◽  
2021 ◽  
Vol 13 (13) ◽  
pp. 1741
Author(s):  
Ahmad Hadi Mohamed Rashidi ◽  
Mohamad Hidayat Jamal ◽  
Mohamad Zaki Hassan ◽  
Siti Salihah Mohd Sendek ◽  
Syazana Lyana Mohd Sopie ◽  
...  
Keyword(s):  
Sea Level Rise ◽  
Sea Level ◽  
Coastal Erosion ◽  
Management Strategies ◽  
Erosion Control ◽  
Beach Erosion ◽  
Coastal Protection ◽  
Sea Level Rise Adaptation ◽  
Erosion Protection ◽  
And Sea Level

The shoreline of Malaysia is exposed to threats of coastal erosion and a rise of sea level. The National Coastal Erosion Study, 2015 reported that 15% of an 8840 km shoreline is currently eroding, where one-third of those falls under the critical and significant categories that require structural protection. The Study of Sea Level Rise in Malaysia, 2017 presented a sea-level increase of 0.67–0.74 mm on average yearly. This study reviewed selected coastal protection structures along the shoreline of Malaysia as an erosion control and sea-level rise adaptation based on coastal management strategies. Hard structures such as rock revetment and breakwater are commonly used as erosion protection systems in the “hold the line” strategy. Increased platform level of seawalls and earth bunds, considered as an “adaptation” approach, are effective in erosion protection and are adaptive to sea-level rise. Mangrove replanting is suitable as a “limited intervention” approach in minimizing the long-term impact of both threats. However, offshore breakwater, groyne, and geotextile tubes are solely for protection purposes and are not as effective for sea-level rise adaptation. As the sea level is continuously increasing, their function as coastal protection will also become less effective. In summary, this comprehensive review on coastal protection in Malaysia will benefit the related agencies on the future assessment.

Coastal development in southwestern Bangladesh: understanding the interplay between storms and sea level rise

2021 ◽  
pp. 030913332110461
Author(s):  
Md. Masidul Haque ◽  
Manoj Kumer Ghosh ◽  
Koichi Hoyanagi
Keyword(s):  
Sea Level Rise ◽  
Sea Level ◽  
Satellite Images ◽  
Morphological Changes ◽  
Coastal Region ◽  
River Mouth ◽  
Sedimentary Facies ◽  
Sediment Supply ◽  
Coastal Development ◽  
Silty Sand

Sea-level rise and sediment supply have influenced coastal morphology and sedimentation on Bangladesh’s southwestern Ganges‐Brahmaputra‐Meghna (GBM) delta coast. Satellite images and geological core from the Haringhata coastal region were analyzed to explain the morphological changes and to understand the influences on deposits. The results derived from satellite images indicate that the southern coastline experienced a retreat that ranges between 2.3 and 2.9 km. In contrast, the eastern and western coastline advanced. The erosion and accretion ratio was 0.29 from 1977 to 1989, while the ratio was higher 2.90–4.77 from 1989 to 2020. Two sedimentary facies were identified using 130 cm thick successions. A parallel to wavy laminated bluish gray mud facies of deeper part was deposited in a marine-influenced environment. A planar to hummocky cross stratified, gray to grayish white silty sand facies of storm overwash deposits overlies the mud facies with sharp contacts. Unimodal to bimodal grain distributions of sandy sediments suggest two sources: sand derived from the beach and mud carried by adjacent tidal rivers and resuspended offshore sediment. Coastline dynamics and sedimentation of the area were influenced by inequality of accommodation and sediment supply ratio in the river mouth. This occurs due to sea-level rise and deficit in upstream water and sediment discharge. Morphological change along the southwestern GBM delta coast was not only caused by wave energy, but also by rising sea levels which shifted sediment accommodation space landward.

The codependence of contributors to regional sea-level rise

2020 ◽  
Author(s):  
Erwin Lambert ◽  
Dewi Le Bars ◽  
Roderik van de Wal
Keyword(s):  
Sea Level Rise ◽  
Sea Level ◽  
Coupled Model ◽  
Ocean Dynamics ◽  
Coastal Protection ◽  
Intergovernmental Panel ◽  
Regional Sea Level ◽  
Intercomparison Project ◽  
Earth System Models ◽  
Regional Sea Level Rise

&lt;p&gt;Science-based policy for coastal protection requires accurate estimates of the uncertainty in regional sea-level rise. These estimates are strongly influenced by the codependence of individual contributors: thermosteric expansion, ocean dynamics, and mass loss from glaciers and ice sheets. In this study, we use model output and parameterisations to quantify the projected total sea-level rise from a set of 15 Earth System Models from the Coupled Model Intercomparison Project (CMIP) 5. We use these model-based estimates of total sea-level rise to quantify the codependence of individual contributors, determined by the full climate response. We find that assumptions on codependence made in recent reports of the Intergovernmental Panel on Climate Change (IPCC) lead to an overestimation in the uncertainty in regional sea-level rise by 20 to 60%. We further conclude that global mean surface temperature rise is a poor indicator for the inter-model difference in regional sea-level rise as it does not account for inter-model differences in atmospheric and oceanic heat distribution and precipitation patterns. The codependencies derived in this study are suitable for application to new projections, allowing for accurate and consistent estimates of the uncertainty in global and regional sea-level rise.&lt;/p&gt;

INUNDATION IMPACTS DUE TO SEA LEVEL RISE AND THE ADAPTATION ASSESSMENTS FOR COASTAL PROTECTION

2019 ◽  
Vol 75 (5) ◽  
pp. I_331-I_337
Author(s):  
Koujiro TSUCHIDA ◽  
Makoto TAMURA ◽  
Naoko KUMANO ◽  
Hiromune YOKOKI
Keyword(s):  
Sea Level Rise ◽  
Sea Level ◽  
Coastal Protection

scholarly journals Contributions of Organic and Mineral Matter to Vertical Accretion in Tidal Wetlands across a Chesapeake Bay Subestuary

2021 ◽  
Vol 9 (7) ◽  
pp. 751
Author(s):  
Jenny R. Allen ◽  
Jeffrey C. Cornwell ◽  
Andrew H. Baldwin
Keyword(s):  
Organic Matter ◽  
Sea Level Rise ◽  
Chesapeake Bay ◽  
Sea Level ◽  
210Pb Dating ◽  
Sediment Supply ◽  
Mineral Matter ◽  
Tidal Wetlands ◽  
Vertical Accretion ◽  
Inorganic Matter

Persistence of tidal wetlands under conditions of sea level rise depends on vertical accretion of organic and inorganic matter, which vary in their relative abundance across estuarine gradients. We examined the relative contribution of organic and inorganic matter to vertical soil accretion using lead-210 (210Pb) dating of soil cores collected in tidal wetlands spanning a tidal freshwater to brackish gradient across a Chesapeake Bay subestuary. Only 8 out of the 15 subsites had accretion rates higher than relative sea level rise for the area, with the lowest rates of accretion found in oligohaline marshes in the middle of the subestuary. The mass accumulation of organic and inorganic matter was similar and related (R2 = 0.37). However, owing to its lower density, organic matter contributed 1.5–3 times more toward vertical accretion than inorganic matter. Furthermore, water/porespace associated with organic matter accounted for 82%–94% of the total vertical accretion. These findings demonstrate the key role of organic matter in the persistence of coastal wetlands with low mineral sediment supply, particularly mid-estuary oligohaline marshes.

Feasibility of sedimentation strategies for the Mekong delta to counterbalance relative sea-level rise

2021 ◽  
Author(s):  
Frances E. Dunn ◽  
Philip S. J. Minderhoud
Keyword(s):  
Land Use ◽  
Sea Level Rise ◽  
Sea Level ◽  
Mekong Delta ◽  
Sediment Deposition ◽  
Sediment Supply ◽  
Sediment Flux ◽  
Relative Sea Level ◽  
Fluvial Sediment ◽  
Relative Sea Level Rise

&lt;p&gt;As one of the largest deltas in the world, the Mekong delta is home to over 17 million people and supports internationally important agriculture. Recently deposited sediment compacts and causes subsidence in deltas, so they require regular sediment input to maintain elevation relative to sea level. These processes are complicated by human activities, which prevent sediment deposition indirectly through reducing fluvial sediment supply and directly through the construction of flood defence infrastructure on deltas, impeding floods which deliver sediment to the land. Additionally, anthropogenic activities increase the rate of subsidence through the extraction of groundwater and other land-use practices.&lt;/p&gt;&lt;p&gt;This research shows the potential for fluvial sediment delivery to compensate for sea-level rise and subsidence in the Mekong delta over the 21st century. We use detailed elevation data and subsidence scenarios in combination with regional sea-level rise and fluvial sediment flux projections to quantify the potential for maintaining elevation relative to sea level in the Mekong delta. We present four examples of localised sedimentation scenarios in specific areas, for which we quantified the potential effectiveness of fluvial sediment deposition for offsetting relative sea-level rise. The presented sediment-based adaptation strategies are complicated by existing land use, therefore a change in water and sediment management is required to effectively use natural resources and employ these adaptation methods. The presented approach could be an exemplar to assess sedimentation strategy feasibility in other delta systems worldwide that are under threat from sea-level rise.&lt;/p&gt;

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