scholarly journals Vulnerability of Venice's coastland to relative sea-level rise

2020 ◽  
Vol 382 ◽  
pp. 689-695
Author(s):  
Luigi Tosi ◽  
Cristina Da Lio ◽  
Sandra Donnici ◽  
Tazio Strozzi ◽  
Pietro Teatini
Keyword(s):  
Sea Level Rise ◽  
Sea Level ◽  
Land Subsidence ◽  
Regional Scale ◽  
Sar Interferometry ◽  
Economic Activities ◽  
Relative Sea Level ◽  
Coastal System ◽  
Relative Sea Level Rise ◽  
The Mean

Abstract. Relative sea-level rise (RSLR), i.e. sea-level rise due to climate changes combined with land subsidence, is one of the processes that is most severely threatening the coastal systems around the world. The Venice coastland forms the major low-lying area in Italy and encompasses a variety of environments, such as farmlands, estuaries, deltas, lagoons and urbanized areas. Valuable ecosystems, historical heritages and economic activities are located in this area. Since most of the territory lies at a ground elevation below or slightly above the mean sea-level, also a few mm yr−1 of land subsidence can seriously impacts on the Venice coastal system. In this study, we present an analysis of the vulnerability to RSLR considering an uneven land subsidence distribution, with an application on the Venice coastland. The analysis is delineated at the regional scale by an index-based model and a proper coupling of various thematic layers, such as high spatial resolution land subsidence data retrieved by satellite SAR interferometry, ongoing and projected sea-level rise trends, and morpho-physiographic setting of the coastland.

Recent measurements of subsidence in the Ganges-Brahmaputra Delta, Bangladesh

2021 ◽  
Author(s):  
Michael S. Steckler ◽  
Bar Oryan ◽  
Md. Hasnat Jaman ◽  
Dhiman R. Mondal ◽  
Céline Grall ◽  
...  
Keyword(s):  
Sea Level Rise ◽  
Sea Level ◽  
Land Subsidence ◽  
Anthropogenic Activity ◽  
Relative Sea Level ◽  
The North ◽  
Active Tectonic ◽  
Relative Sea Level Rise ◽  
Tectonic Boundaries ◽  
The Ganges

<p>Deltas, the low-lying land at rivers mouths, are sensitive to the delicate balance between sea level rise, land subsidence and sedimentation. Bangladesh and the Ganges-Brahmaputra Delta (GBD) have been highlighted as a region at risk from sea level rise, but reliable estimates of land subsidence have been limited. While early studies in the GBD suggested high rates of relative sea level rise, recent papers estimate more modest rates. Our objective is to better quantify the magnitude, spatial variability, and depth variation of compaction and subsidence in the GBD in order to better evaluate the processes controlling it and the pattern of relative sea level rise in this vulnerable region.</p><p>With support from the Bangladesh Water Development Board, we have rehabilitated previously installed GNSS and installed new GNSS co-located with Rod Surface Elevation Tables (RSET) to better understand the balance of subsidence and sedimentation in the coastal zone in SW Bangladesh, which is less affected by the active tectonic boundaries to the north and the east. The continuous GNSSs installed in 2003 and 2012 were mounted on reinforced concrete building roofs. GPS stations in the area yield subsidence rate estimates of 3-7 mm/y.  To densify the subsidence data, in early 2020 we resurveyed 48 concrete Survey of Bangladesh geodetic monuments in SW Bangladesh that were installed in 2002. Although only measured at the start and end of the period, the time span between the two measurements is ~18 years enabling us to estimate subsidence over this timespan.</p><p>Preliminary results show that about ½ the sites yielded very high subsidence rates; repeat measurements confirm the suspicion that the monuments at these sites are unstable and have undergone localized subsidence from settling or anthropogenic activity. The remaining sites show an increase in subsidence from the NW to the SE, consistent with estimates of average Holocene subsidence (Grall et al., 2018). However, rates from the campaign stations are much higher than those from continuous GNSS sites, but only slightly higher than an RSET site. We interpret that the continuous building GNSS omit very shallow compaction-related subsidence, while RSETs neglect deep subsidence. This is further reinforced by results from a compaction meter consisting of 6 wells from 20 to 300 m depth with vertical optical fiber strainmeters in each well. They show a decrease in compaction with depth. While initial results require further investigation, we highlight the importance of multiple methodologies for interpreting subsidence rates--deep, shallow, natural, anthropogenic--in vulnerable delta regions.</p>

scholarly journals Land Subsidence in Chiayi, Taiwan, from Compaction Well, Leveling and ALOS/PALSAR: Aquaculture-Induced Relative Sea Level Rise

2017 ◽  
Vol 10 (2) ◽  
pp. 40 ◽  
Author(s):  
Wei-Chia Hung ◽  
Cheinway Hwang ◽  
Yi-An Chen ◽  
Lei Zhang ◽  
Kuan-Hung Chen ◽  
...  
Keyword(s):  
Sea Level Rise ◽  
Sea Level ◽  
Land Subsidence ◽  
Alos Palsar ◽  
Relative Sea Level ◽  
Relative Sea Level Rise

scholarly journals COUNTERMEASURE AGAINST EROSION BEHIND SUBMERGED BREAKWATER DUE TO SEA LEVEL RISE

2018 ◽  
pp. 62
Author(s):  
Yoshiaki Kuriyama ◽  
Masayuki Banno
Keyword(s):  
Sea Level Rise ◽  
Sea Level ◽  
Land Subsidence ◽  
West Coast ◽  
Shoreline Change ◽  
Sandy Beaches ◽  
Beach Erosion ◽  
Relative Sea Level ◽  
Submerged Breakwater ◽  
Relative Sea Level Rise

Submerged breakwaters are considered to be preferable countermeasures against beach erosion where the availability of sediments for nourishment is limited and tourism is prevalent because submerged breakwaters do not interfere with the view of the horizon from the shore. However, sandy beaches protected by submerged breakwaters are assumed to be vulnerable to relative sea level rise (SLR) and land subsidence because the crests of submerged breakwaters are below sea level. Kuriyama and Banno (2016) numerically predicted the future shoreline change under SLR and land subsidence on the Niigata West coast in Japan, which is protected by submerged breakwaters. The prediction showed that the shoreline will retreat 60 m over the next 100 years. In this study, we investigated the effects of countermeasures against the erosion due to SLR and land subsidence.

scholarly journals Land subsidence contributions to relative sea level rise at tide gauge Galveston Pier 21, Texas

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Yi Liu ◽  
Jiang Li ◽  
John Fasullo ◽  
Devin L. Galloway
Keyword(s):  
Gulf Of Mexico ◽  
Sea Level Rise ◽  
Sea Level ◽  
Land Subsidence ◽  
Flood Hazard ◽  
Tide Gauge ◽  
Mitigation Strategies ◽  
Relative Sea Level ◽  
Aquifer System ◽  
Relative Sea Level Rise

Abstract Relative sea level rise at tide gauge Galveston Pier 21, Texas, is the combination of absolute sea level rise and land subsidence. We estimate subsidence rates of 3.53 mm/a during 1909–1937, 6.08 mm/a during 1937–1983, and 3.51 mm/a since 1983. Subsidence attributed to aquifer-system compaction accompanying groundwater extraction contributed as much as 85% of the 0.7 m relative sea level rise since 1909, and an additional 1.9 m is projected by 2100, with contributions from land subsidence declining from 30 to 10% over the projection interval. We estimate a uniform absolute sea level rise rate of 1.10 mm ± 0.19/a in the Gulf of Mexico during 1909–1992 and its acceleration of 0.270 mm/a2 at Galveston Pier 21 since 1992. This acceleration is 87% of the value for the highest scenario of global mean sea level rise. Results indicate that evaluating this extreme scenario would be valid for resource-management and flood-hazard-mitigation strategies for coastal communities in the Gulf of Mexico, especially those affected by subsidence.

The existential crisis of the Mekong delta: Impact of accelerating land subsidence

2020 ◽  
Author(s):  
Philip S.J. Minderhoud ◽  
Gilles Erkens ◽  
Hans Middelkoop ◽  
Esther Stouthamer
Keyword(s):  
Sea Level Rise ◽  
Sea Level ◽  
Land Subsidence ◽  
Mekong Delta ◽  
Relative Sea Level ◽  
Natural Processes ◽  
Existential Crisis ◽  
The World ◽  
Relative Sea Level Rise ◽  
Imminent Threat

<p>Land subsidence is one of the slowest, natural processes faced by deltas throughout the world, yet it acts as an important catalyst which exacerbates all other threats associated with relative sea-level rise, such as increased flood vulnerability and salinization. This presentation summarizes the results of five years of research on land subsidence in the Mekong delta and highlights the major advances in approaches and insights gained in subsidence processes and rates of an entire mega-delta system.</p><p>The Mekong delta is heading towards an existential crisis as land subsidence rates are rapidly accelerating over the past decades up to ~5 cm/yr. As sediment starvation in the Mekong river greatly reduces the adaptive capacity to counterbalance subsidence, this results in wide-spread loss of delta elevation. With the Mekong delta having an average elevation of less than 1 meter above local mean sea level, these elevated rates of relative sea-level rise pose an imminent threat of land loss and permanent submersion in the coming decades.</p><p>Like in many densely populated and rapidly developing coastal-deltaic areas around the world, the main anthropogenic driver that causes accelerated subsidence is the overexploitation of groundwater. A range of future delta elevation projections, considering sea-level rise and simulated groundwater extraction-induced subsidence following extraction pathways, show the dire situation of the delta in spatial-temporal explicit maps of future elevation relative to local sea level.</p><p>Adequate (ground)water management aimed at strongly reducing current extractions is key in mitigating accelerating sinking rates and crucial to ensure the survival of the Mekong delta. The window of opportunity to act is swiftly closing as the delta is rapidly running out of elevation, and therefore time.</p>

Relative sea-level rise during the Main Postglacial Transgression in NE Scotland, U.K.

1999 ◽  
Vol 90 (1) ◽  
pp. 1-27 ◽  
Author(s):  
D. E. Smith ◽  
C. R. Firth ◽  
C. L. Brooks ◽  
M. Robinson ◽  
P. E. F. Collins
Keyword(s):  
Sea Level Rise ◽  
Sea Level ◽  
Sea Level Changes ◽  
Relative Sea Level ◽  
Sea Levels ◽  
Relative Sea Level Rise ◽  
The Mean ◽  
Run Up ◽  
Storegga Slide

AbstractFlandrian (Holocene) relative sea level changes in the lower Ythan valley, NE Scotland, U.K., are inferred from detailed stratigraphical evidence including microfossil analysis and radiocarbon assay. The principal event recorded is the Main Postglacial Transgression, which was under way in the area by c. 8300 and had culminated before c. 4000 radiocarbon years BP. It is concluded that the rise in relative sea levels during the transgression in the area exceeded 12 m; that the mean rate of rise there was 8·05 mm a−1 between c. 8300 and c. 7100 radiocarbon years BP, or 7·09 mm a−1 based upon calibrated dates for the same period, before declining markedly to 1·75 mm a−1 (radiocarbon) or 1·86 mm a−1 (calibrated) to the culmination of the event. By comparison with other sites, the culmination appears to have been time-transgressive in eastern Scotland. Deposits of the Second Storegga Slide tsunami, which occurred during the Main Postglacial Transgression, are present in the Ythan valley, where the sediment run-up of the event at the sites studied is estimated to have been within the range 2·99–5·19 m.

scholarly journals Quantifying Thresholds of Barrier Geomorphic Change in a Cross-Shore Sediment Partitioning Model

2020 ◽  
Author(s):  
Daniel J. Ciarletta ◽  
Jennifer L. Miselis ◽  
Justin L. Shawler ◽  
Christopher J. Hein
Keyword(s):  
Sea Level Rise ◽  
Sea Level ◽  
Cross Sections ◽  
Sediment Flux ◽  
State Transitions ◽  
Morphologic Change ◽  
Relative Sea Level ◽  
Coastal System ◽  
Sea Levels ◽  
Relative Sea Level Rise

Abstract. Barrier coasts, including barrier islands, beach-ridge plains, and associated landforms, can assume a broad spectrum of morphologies over decadal scales that reflect conditions of sediment availability, accommodation, and relative sea-level rise. However, the quantitative thresholds of these controls on barrier-system behavior remain largely unexplored, even as modern sea-level rise and anthropogenic modification of sediment availability increasingly reshape the world’s sandy coastlines. In this study, we conceptualize barrier coasts as sediment partitioning frameworks, distributing sand delivered from the shoreface to the subaqueous and subaerial components of the coastal system. Using an idealized morphodynamic model, we explore thresholds of behavioral/morphologic change over decadal to centennial timescales, simulating barrier evolution within quasi-stratigraphic morphological cross-sections. Our results indicate a wide diversity of barrier behaviors can be explained by the balance of fluxes delivered to the beach versus the dune/backbarrier, including previously understudied forms of transgression that allow the subaerial system to continue accumulating sediment during landward migration. Most importantly, our results show that barrier state transitions between progradation, cross-shore amalgamation, aggradation, and transgression are controlled largely through balances within a narrow range of relative sea-level rise and sediment flux. This suggests that, in the face of rising sea levels, subtle changes in sediment fluxes could result in significant changes in barrier morphology. We also demonstrate that modeled barriers with reduced vertical sediment accommodation are highly sensitive to the magnitude and direction of shoreface fluxes. Therefore, natural barriers with limited sediment accommodation could allow for exploration of the future effects of sea-level rise and changing flux magnitudes over a period of years as opposed to the decades required for similar responses in sediment-rich barrier systems. Finally, because our model creates stratigraphy generated under different input parameters, we propose it could be used in combination with stratigraphic data to hindcast the sensitivity of existing barriers and infer changes in pre-historic morphology, which we anticipate will provide a baseline to assess the reliability of forward modeling predictions.

How to tackle spatial variability and temporal non-linearity in land subsidence in unconsolidated coastal environments?

2021 ◽  
Author(s):  
Philip S.J. Minderhoud ◽  
Claudia Zoccarato ◽  
Riccardo Xotta ◽  
Pietro Teatini
Keyword(s):  
Sea Level Rise ◽  
Sea Level ◽  
Land Subsidence ◽  
Land Surface ◽  
Field Experiments ◽  
Data Interpretation ◽  
Coastal Environments ◽  
Relative Sea Level ◽  
Aquifer System ◽  
Relative Sea Level Rise

<p>Accurate land subsidence quantifications are of growing importance as relative sea-level rise in unconsolidated coastal environments is increasingly dominated by subsidence. Land subsidence, especially in unconsolidated settings, is the result of a complex interplay and sum of a range of different subsurface processes. As these processes can be spatially and temporally very variable, it requires more than (point and/or land surface) measurements to accurately quantify subsidence, especially when projections of subsidence are required for example to assess future relative sea-level rise. This requires first of all a thorough understanding of subsidence drivers and subsurface processes in a 4D perspective (3D including time) and secondly data interpretation methods and tools to handle the complex coupling of these interrelated processes to enable spatial-temporal quantification and projection of coastal subsidence.</p><p>We present a set of novel approaches, with which we aim to move our capacity to accurately capture and simulate the highly dynamic behaviour of subsidence processes. The approaches range from novel field experiments to advanced interpretation of sedimentary information in coastal-deltaic setting to gain important input for numerical modelling, and to newly-developed state-of-the-art 3D numerical simulators. Through these combined methodologies we aim to improve our capacity to assess both natural subsidence processes, like natural compaction, and anthropogenic-induced processes, like aquifer-system compaction following overexploitation in unconsolidated settings. This will ultimately contribute, for example through scenario modelling of anthropogenic drivers, to create reliable future projections of land subsidence which will enable sound projections of relative sea-level rise.</p>

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