scholarly journals The Geomorphology of Farewell Spit and Its Sensitivity to Sea-Level Rise

2021 ◽  
Author(s):  
◽  
Helen M Tribe
Keyword(s):  
Sea Level Rise ◽  
Sea Level ◽  
Spring Tide ◽  
Tidal Flats ◽  
Water Levels ◽  
Aerial Photographs ◽  
Storm Events ◽  
14C Dating ◽  
Sediment Reworking ◽  
High Degree

<p>Sand-dominated barriers are highly sensitive coastal systems which alter their morphology in response to rising sea level, undergoing extensive sediment reworking as wave activity reaches further inland. Farewell Spit, South Island, New Zealand, is a sand-dominated barrier spit which extends 25kms eastward from the mainland, enclosing the northwestern corner of the macro-tidal Golden Bay. During spring tide cycles low-lying areas of the Spit become completely inundated. The aim of this study is to establish the morphological stability of Farewell Spit and its potential response to the latest IPCC projected eustatic sea-level rise of 0.48m (A1B scenario) by the end of this century. GIS analysis of aerial photographs and the identification of 137Cs signatures within the dunes have shown a high degree of mobility in the Spit's features over the past 55 years. Vegetation increased by 75%, mainly due to the introduction of A arenaria, which has also led to the development of foredunes prograding up to 142m over the tidal flats. Barchan dunes on the Spit are also highly mobile migrating at up to 30m/y. The high amount of sediment movement along the spit is reflected in the sedimentology of the tidal flats, which show layers of aeolian transported fine, well-sorted sand several centimetres thick. The predominance of medium sand shows that reworking appears to have occurred on these flats due to storm events in Golden Bay, and like the dunes, 14C dating indicates they are very young features Projected sea-level rise was modelled to assess the vulnerability of low-lying areas of the Spit to tidal flooding. Deeper water levels in the two tidal channels which currently flood across the Spit are expected and there is a risk of additional channels opening, one being very near to the contact between the Spit and mainland. The mobility of the dune systems may however buffer some of these processes by providing natural defences against the sea. Barrier roll over does not appear to be an important process as it appears to be too wide to allow for washover. It is concluded that under current sea-level rise predictions Farewell Spit will not transgress landward but will be subject to exacerbated erosion.</p>

scholarly journals The Geomorphology of Farewell Spit and Its Sensitivity to Sea-Level Rise

2021 ◽  
Author(s):  
◽  
Helen M Tribe
Keyword(s):  
Sea Level Rise ◽  
Sea Level ◽  
Spring Tide ◽  
Tidal Flats ◽  
Water Levels ◽  
Aerial Photographs ◽  
Storm Events ◽  
14C Dating ◽  
Sediment Reworking ◽  
High Degree

<p>Sand-dominated barriers are highly sensitive coastal systems which alter their morphology in response to rising sea level, undergoing extensive sediment reworking as wave activity reaches further inland. Farewell Spit, South Island, New Zealand, is a sand-dominated barrier spit which extends 25kms eastward from the mainland, enclosing the northwestern corner of the macro-tidal Golden Bay. During spring tide cycles low-lying areas of the Spit become completely inundated. The aim of this study is to establish the morphological stability of Farewell Spit and its potential response to the latest IPCC projected eustatic sea-level rise of 0.48m (A1B scenario) by the end of this century. GIS analysis of aerial photographs and the identification of 137Cs signatures within the dunes have shown a high degree of mobility in the Spit's features over the past 55 years. Vegetation increased by 75%, mainly due to the introduction of A arenaria, which has also led to the development of foredunes prograding up to 142m over the tidal flats. Barchan dunes on the Spit are also highly mobile migrating at up to 30m/y. The high amount of sediment movement along the spit is reflected in the sedimentology of the tidal flats, which show layers of aeolian transported fine, well-sorted sand several centimetres thick. The predominance of medium sand shows that reworking appears to have occurred on these flats due to storm events in Golden Bay, and like the dunes, 14C dating indicates they are very young features Projected sea-level rise was modelled to assess the vulnerability of low-lying areas of the Spit to tidal flooding. Deeper water levels in the two tidal channels which currently flood across the Spit are expected and there is a risk of additional channels opening, one being very near to the contact between the Spit and mainland. The mobility of the dune systems may however buffer some of these processes by providing natural defences against the sea. Barrier roll over does not appear to be an important process as it appears to be too wide to allow for washover. It is concluded that under current sea-level rise predictions Farewell Spit will not transgress landward but will be subject to exacerbated erosion.</p>

Event and decadal-scale modeling of barrier island restoration designs for decision support

Shore & Beach ◽  
2020 ◽  
pp. 49-57
Author(s):  
Joseph Long ◽  
P. Soupy Dalyander ◽  
Michael Poff ◽  
Brian Spears ◽  
Brett Borne ◽  
...  
Keyword(s):  
Sea Level Rise ◽  
Sea Level ◽  
Water Levels ◽  
Storm Events ◽  
Model Framework ◽  
Modeling Framework ◽  
Dune System ◽  
Island Restoration ◽  
Decadal Scale ◽  
Wide Range

An interdisciplinary project team was convened to develop a modeling framework that simulates the potential impacts of storms and sea level-rise to habitat availability at Breton Island, Louisiana, for existing conditions and potential future restoration designs. The model framework was iteratively developed through evaluation of model results at multiple checkpoints. A methodology was developed for characterizing regional wave and water levels, and the numerical model XBeach was used to simulate the potential impacts from a wide range of storm events. Simulations quantified the potential for erosion, overwash, and inundation of the pre- and post-restoration beach and dune system and were used as a preliminary screening of restoration designs. The model framework also incorporated a computationally efficient method to evaluate the impacts of storms, long-term shoreline changes, and relative sea level rise over a 15-year time period, in order to evaluate the effect of the preferred restoration alternative on habitat distribution. Results directly informed engineering design decisions and expedited later project stages including the construction permitting process.

Effects of mean sea level rise and tidal flat growth on tides and storm surge events in the Elbe estuary

2021 ◽  
Author(s):  
Tara Mahavadi ◽  
Elisabeth Rudolph ◽  
Rita Seiffert ◽  
Norbert Winkel
Keyword(s):  
Sea Level Rise ◽  
Sea Level ◽  
Storm Surge ◽  
Tidal Flat ◽  
Tidal Flats ◽  
Water Levels ◽  
Elbe Estuary ◽  
Tidal Amplitude ◽  
Tidal Dynamics ◽  
Mean Sea Level

&lt;p&gt;Future mean sea level rise will influence tidal dynamics and storm surge events in estuaries. The bathymetry in estuaries and coastal areas will also be affected by mean sea level rise, since it is in a morphodynamic equilibrium with hydrodynamic forces. Tidal flats, which are an important component of coastal protection, will grow to a certain extent with mean sea level rise in case of sufficient sediment availability.&lt;/p&gt;&lt;p&gt;With the help of a highly resolved hydrodynamic-numerical model of the German Bight (North Sea), we analyse the potential influence of mean sea level rise and vertical growth of tidal flats on tidal dynamics and storm surge events in the Elbe estuary.&lt;/p&gt;&lt;p&gt;The results show an increase of tidal amplitude and storm surge water levels due to mean sea level rise. A bathymetric rise of tidal flats in the German Bight and the mouth of the Elbe estuary leads to a decrease in storm surge water level and tidal amplitude compared to the scenario with sole mean sea level rise without a change in bathymetry. Further analyses show, how geometric parameters of the Elbe estuary are changing due to mean sea level rise and tidal flat growth. These changes in geometry influence tidal dynamics and can therefore be an explanation for the observed changes in tidal amplitude and storm surge water levels.&lt;/p&gt;&lt;p&gt;These findings enable a better understanding of future changes in the Elbe estuary and support coastal managers in decision making processes concerning adaptation options to reduce the impacts of climate change.&lt;/p&gt;

scholarly journals Coastal wetland resilience to climate change: modelling ecosystem response to rising sea level and salinity in a variable climate

2019 ◽  
Vol 2 (1) ◽  
pp. 1-20
Author(s):  
S.E. Grenfell ◽  
F. Fortune ◽  
M.F. Mamphoka ◽  
N. Sanderson
Keyword(s):  
Climate Change ◽  
Sea Level Rise ◽  
Sea Level ◽  
Coastal Wetland ◽  
Spring Tide ◽  
Water Levels ◽  
Recurrence Interval ◽  
Sediment Accretion ◽  
Tidal Variation ◽  
The Impact

We investigate coastal wetland ecosystem resilience to sea level rise by modelling sea level rise trajectories and the impact on vegetation communities for a coastal wetland in South Africa. The rate of sediment accretion was modelled relative to IPCC sea level rise estimates for multiple RCP scenarios. For each scenario, inundation by neap and spring tide and the 2, 4, and 8 year recurrence interval water level was modelled over a period of 200 years. When tidal variation is considered, the rate of sediment accretion exceeds rising sea levels associated with climate change, resulting in no major changes in terms of inundation. When sea level rise scenarios were modelled in conjunction with recurrence interval water levels, flooding of the coastal wetland was much greater than current levels at 1 in 4 and 1 in 8 year events. In the long term, increases in salinity may cause a reduction in Phragmites australis cover. Very small increases in depth and frequency of inundation are likely to cause an expansion of samphire species at the expense of Juncus spp. The study suggests that for this wetland, variability in flow may be a key factor in balancing wetland resilience.

scholarly journals Sea level rise and its impact on storm surge and tide in Shanghai

MAUSAM ◽  
2021 ◽  
Vol 48 (4) ◽  
pp. 541-554
Author(s):  
ZENGHAO QIN
Keyword(s):  
Sea Level Rise ◽  
Sea Level ◽  
Storm Surge ◽  
Dynamic Models ◽  
Spring Tide ◽  
Water Levels ◽  
Ground Subsidence ◽  
Past Century ◽  
The Mean ◽  
The Impact

Based on both the historical tidal gauge and ground subsidence records for the seven stations in Shanghai region, a non-linear statistical model fitting the variation of the mean annual eustatic sea level (ESL) is established to reveal the characteristics of the ESL in the past century and to estimate the mean annual relative sea level (RSL) in the next five decades by the model extrapolation for Shanghai region. The estimated values of the sea level rises are assessed to be fairly reasonable. The impact of the estimated sea level rise in the coming decades on the storm surges and tides in Shanghai region is numerically computed by using the two-dimensional nonlinear storm surge and tide dynamic models. In addition, on the basis of numerical integration of the same dynamic model, the probable maximum water levels resulting from the RSL in the coming decades are also estimated by the probable optimal combination of the track, intensity, landfall site, incident angle of tropical cyclone and spring tide.  

scholarly journals Economic damages from Hurricane Sandy attributable to sea level rise caused by anthropogenic climate change

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Benjamin H. Strauss ◽  
Philip M. Orton ◽  
Klaus Bittermann ◽  
Maya K. Buchanan ◽  
Daniel M. Gilford ◽  
...  
Keyword(s):  
Climate Change ◽  
Sea Level Rise ◽  
Sea Level ◽  
East Coast ◽  
The United States ◽  
Hurricane Sandy ◽  
Water Levels ◽  
Anthropogenic Climate Change ◽  
Economic Damage ◽  
Sea Levels

AbstractIn 2012, Hurricane Sandy hit the East Coast of the United States, creating widespread coastal flooding and over $60 billion in reported economic damage. The potential influence of climate change on the storm itself has been debated, but sea level rise driven by anthropogenic climate change more clearly contributed to damages. To quantify this effect, here we simulate water levels and damage both as they occurred and as they would have occurred across a range of lower sea levels corresponding to different estimates of attributable sea level rise. We find that approximately $8.1B ($4.7B–$14.0B, 5th–95th percentiles) of Sandy’s damages are attributable to climate-mediated anthropogenic sea level rise, as is extension of the flood area to affect 71 (40–131) thousand additional people. The same general approach demonstrated here may be applied to impact assessments for other past and future coastal storms.

scholarly journals Impact Assessment Analysis of Sea Level Rise in Denmark: A Case Study of Falster Island, Guldborgsund

2021 ◽  
Vol 13 (13) ◽  
pp. 7503
Author(s):  
Alexander Boest-Petersen ◽  
Piotr Michalak ◽  
Jamal Jokar Arsanjani
Keyword(s):  
Climate Change ◽  
Impact Assessment ◽  
Sea Level Rise ◽  
Sea Level ◽  
Alternative Methods ◽  
Projection Data ◽  
Storm Events ◽  
Cascading Effects ◽  
Local Levels

Anthropogenically-induced climate change is expected to be the contributing cause of sea level rise and severe storm events in the immediate future. While Danish authorities have downscaled the future oscillation of sea level rise across Danish coast lines in order to empower the coastal municipalities, there is a need to project the local cascading effects on different sectors. Using geospatial analysis and climate change projection data, we developed a proposed workflow to analyze the impacts of sea level rise in the coastal municipalities of Guldborgsund, located in Southeastern Denmark as a case study. With current estimates of sea level rise and storm surge events, the island of Falster can expect to have up to 19% of its landmass inundated, with approximately 39% of the population experiencing sea level rise directly. Developing an analytical workflow can allow stakeholders to understand the extent of expected sea level rise and consider alternative methods of prevention at the national and local levels. The proposed approach along with the choice of data and open source tools can empower other communities at risk of sea level rise to plan their adaptation.

scholarly journals Quantifying Uncertainty in Exposure to Coastal Hazards Associated with Both Climate Change and Adaptation Strategies: A U.S. Pacific Northwest Alternative Coastal Futures Analysis

Water ◽  
2021 ◽  
Vol 13 (4) ◽  
pp. 545
Author(s):  
Alexis K. Mills ◽  
Peter Ruggiero ◽  
John P. Bolte ◽  
Katherine A. Serafin ◽  
Eva Lipiec
Keyword(s):  
Climate Change ◽  
Sea Level Rise ◽  
Sea Level ◽  
Performance Metrics ◽  
Coastal Flooding ◽  
Water Levels ◽  
Coastal Hazards ◽  
Policy Decisions ◽  
Management Decisions ◽  
Quantifying Uncertainty

Coastal communities face heightened risk to coastal flooding and erosion hazards due to sea-level rise, changing storminess patterns, and evolving human development pressures. Incorporating uncertainty associated with both climate change and the range of possible adaptation measures is essential for projecting the evolving exposure to coastal flooding and erosion, as well as associated community vulnerability through time. A spatially explicit agent-based modeling platform, that provides a scenario-based framework for examining interactions between human and natural systems across a landscape, was used in Tillamook County, OR (USA) to explore strategies that may reduce exposure to coastal hazards within the context of climate change. Probabilistic simulations of extreme water levels were used to assess the impacts of variable projections of sea-level rise and storminess both as individual climate drivers and under a range of integrated climate change scenarios through the end of the century. Additionally, policy drivers, modeled both as individual management decisions and as policies integrated within adaptation scenarios, captured variability in possible human response to increased hazards risk. The relative contribution of variability and uncertainty from both climate change and policy decisions was quantified using three stakeholder relevant landscape performance metrics related to flooding, erosion, and recreational beach accessibility. In general, policy decisions introduced greater variability and uncertainty to the impacts of coastal hazards than climate change uncertainty. Quantifying uncertainty across a suite of coproduced performance metrics can help determine the relative impact of management decisions on the adaptive capacity of communities under future climate scenarios.

Modelling the climate change impact on the largest White Sea estuarine areas

2021 ◽  
Author(s):  
Evgeniya Panchenko ◽  
Andrei Alabyan ◽  
Inna Krylenko ◽  
Serafima Lebedeva
Keyword(s):  
Climate Change ◽  
Sea Level Rise ◽  
Sea Level ◽  
River Runoff ◽  
White Sea ◽  
Water Levels ◽  
Hydrodynamic Modelling ◽  
The White Sea ◽  
Runoff Changes ◽  
Flow Velocities

&lt;p&gt;Possible sea level rise and changes in hydrological regime of rivers are the major threats to estuarine systems. The sensibility of hydrodynamic regime of the Northern Dvina delta and the Onega estuary under various scenarios of climate change has been investigated. Hydrodynamic models HEC-RAS (USA, US Army Corps of Engineers Hydrologic Engineering Center) and STREAM_2D (Russia, authors V.Belikov et.al.) were used for analysis of estuarine flow regime (variations of water levels, discharges and flow velocities throughout tidal cycles). Input runoff changes were simulated for different climate scenarios using ECOMAG model (Russia, author Yu.Motovilov) based on data of global climate models (GSM) of CMIP5 project for the White Sea region.&lt;/p&gt;&lt;p&gt;ECOMAG modelling has demonstrated that the maximum river discharges averaged for 30-year period 2036 &amp;#8211; 2065 can reduce for about 20 &amp;#8211; 27% for the Onega and 15 &amp;#8211; 20% for the Northern Dvina river compared against the historical period 1971 &amp;#8211; 2000.Averaged minimum river discharges can reduce for about 33 &amp;#8211; 45% for the Onega and 30 &amp;#8211; 40% for the Northern Dvina.&lt;/p&gt;&lt;p&gt;The White Sea level rise by 0.27 m in average (with inter-model variation from 0.20 to 0.38 m) can took place by the middle of the XXI century according to input data of GSM models. The 12 scenarios of estuarine hydrodynamic changes were simulated for the both rivers based on combining river runoff changes and sea level elevation.&lt;/p&gt;&lt;p&gt;In general, the expected flow changes are negative for the local industry and population. According to modelling results for &amp;#8216;high runoff/spring tide&amp;#8217; scenarios the flooding area in the Northern Dvina delta will increase by 13-20% depending on the intensity of sea level rise. In the low water seasons the distance from the river mouth to the upper boundary of the reach, where reverse currents can be observed, will move upstream by 8 - 36 km depending of sea/river conditions due to decrease in minimum river runoff. It may adversely effect on shipping conditions at the city of Arkhangelsk and on brackish water intrusion up-to industrial and communal water intakes.&lt;/p&gt;&lt;p&gt;The reverse currents also will intensify in the Onega estuary (tidal flow velocities increase for 11 &amp;#8211; 19%) that leads to the change of the sediment regime and can significantly deteriorate the navigation conditions at the seaport of the Onega town. The problem of the intensification of salt intrusion can arise there as well.&lt;/p&gt;&lt;p&gt;The research was supported by the Russian Foundation for Basic Research (Projects No. 18- 05-60021 in development of the scenarios; No. 19-35-90032 in providing hydrodynamic modelling of the Onega; Project No. 19-35-60032 in providing hydrodynamic modelling of the Northern Dvina).&lt;/p&gt;

A 6000-year record of ecological and hydrological changes from Laguna de la Leche, north coastal Cuba

2007 ◽  
Vol 67 (1) ◽  
pp. 69-82 ◽  
Author(s):  
Matthew C. Peros ◽  
Eduard G. Reinhardt ◽  
Anthony M. Davis
Keyword(s):  
Sea Level Rise ◽  
Sea Level ◽  
Plant Macrofossils ◽  
Water Levels ◽  
Loss On Ignition ◽  
Coastal Lake ◽  
Freshwater Gastropods ◽  
Level Increase ◽  
Pollen Rain ◽  
Calcareous Microfossils

AbstractLaguna de la Leche, north coastal Cuba, is a shallow (≤ 3 m), oligohaline (∼ 2.0–4.5‰) coastal lake surrounded by mangroves and cattail stands. A 227-cm core was studied using loss-on-ignition, pollen, calcareous microfossils, and plant macrofossils. From ∼6200 to ∼ 4800 cal yr BP, the area was an oligohaline lake. The period from ∼ 4800 to ∼ 4200 cal yr BP saw higher water levels and a freshened system; these changes are indicated by an increase in the regional pollen rain, as well as by the presence of charophyte oogonia and an increase in freshwater gastropods (Hydrobiidae). By ∼ 4000 cal yr BP, an open mesohaline lagoon had formed; an increase in salt-tolerant foraminifers suggests that water level increase was driven by relative sea level rise. The initiation of Laguna de la Leche correlates with a shift to wetter conditions as indicated in pollen records from the southeastern United States (e.g., Lake Tulane). This synchronicity suggests that sea level rise caused middle Holocene environmental change region-wide. Two other cores sampled from mangrove swamps in the vicinity of Laguna de la Leche indicate that a major expansion of mangroves was underway by ∼ 1700 cal yr BP.

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