scholarly journals CLIMATE VARIABILITY INDUCED SHIFTS OF THE WAVE CLIMATE IN MEXICO

2020 ◽  
pp. 21
Author(s):  
Rodolfo Silva ◽  
Itxaso Oderiz ◽  
Thomas Mortlock ◽  
Ismael Marino-Tapia
Keyword(s):  
Sediment Transport ◽  
Southern Oscillation ◽  
Wave Climate ◽  
Global Scale ◽  
Wave Direction ◽  
Erosion Risk ◽  
Primary Driver ◽  
Important Challenge ◽  
Offshore Wave

Inter-annual variability of wave climates is important for coastal risk assessment because these fluctuations can increase or decrease seasonal erosion risk (Wahl and Plant 2015). Understanding how long-term variability affects the seasonality of sediment transport is an important challenge in risk assessments (Toimil et al. 2020). There have been many attempts to quantify long-term variability in offshore wave climate, as this is the primary driver of coastal processes on sandy coasts. However, there is very little work on how the long-term variability of wave climate influences sediment transport. One of the most important drivers of sediment transport is the mean wave direction of incoming waves (Barnard et al. 2015; Hemer, Church, and Hunter 2010; Morim et al. 2019), although it is still not fully understood. An important contribution in this regard is the work of (Barnard et al. 2015), who found that El Nio Southern Oscillation (ENSO) dominates coastal vulnerability in the Pacific Ocean. On the other hand, several works at global scale (Godoi and Torres Junior 2020; Reguero, Losada, and Mendez 2019; Stopa and Cheung 2014) have found that ENSO is the climatic driver that most affects the interannual variability of the wave climate. However, understanding how ENSO impacts wave direction is still lacking.Recorded Presentation from the vICCE (YouTube Link): https://youtu.be/_M5Mxm7PnQg

Reconstructing the initial shape of volcanic islands to quantify long-term coastal erosion

2021 ◽  
Author(s):  
Rémi Bossis ◽  
Vincent Regard ◽  
Sébastien Carretier
Keyword(s):  
Coastal Erosion ◽  
Erosion Rate ◽  
Developed Countries ◽  
Global Scale ◽  
Radial Symmetry ◽  
Wave Direction ◽  
Initial Shape ◽  
Vertical Movements ◽  
Volcanic Islands

<p>The global solid flux from continent to ocean is usually reduced to the input of sediments from rivers, and is estimated at approximately 20 Gt/year. Another input of sediments to ocean is coastal erosion, but this flux is difficult to estimate on a global scale and it is often neglected, perhaps wrongly according to regional studies [1,2]. Most studies attempting to quantify coastal erosion have focused on the coasts of developed countries and are limited to the timescale of decades or less [3]. The difficulty in quantifying long-term coastal erosion is that there are still many uncertainties about the factors controlling coastal erosion on this time scale, and it would be necessary to know the initial geometry of coastlines to calculate an eroded volume.</p><p>Volcanic islands, as geomorphological objects, seem to be very good objects of study to remedy these limitations. Indeed, many young volcanic islands are made of only one central edifice with a strong radial symmetry despite its degradation by erosion [4,5]. By knowing the age of an island and by comparing reconstructed shape with current shape, we can calculate a total eroded volume and an integrated average coastal erosion rate on the age of the island. Moreover, due to their geographical, petrological and tectonic diversity, volcanic islands allow to compare the influence of different factors on long-term coastal erosion, such as climate, wave direction and height, rock resistance or vertical movements. Thus, we will be able to prioritize them to propose coastal erosion laws that would applicable to all rocky coasts.</p><p>Here we built on previous works that have used aerial geospatial databases to reconstruct the initial shape of these islands [6,7] but we improve this approach by using offshore topographic data to determine the maximum and initial extension of their coasts. From both onshore and offshore topographies, we determine a long-term mean coastal erosion rate and we quantify precisely its uncertainty. Using the example of Corvo Island, in the Azores archipelago, we show how our approach allows us to obtain first estimates of long-term coastal erosion rate around this island.</p><p> </p><p><strong>References</strong></p><p> </p><p>[1] Landemaine V. (2016). Ph.D. thesis, University of Rouen.</p><p>[2] Rachold V., Grigoriev M.N., Are F.E., Solomon S., Reimnitz E., Kassens H., Antonow M. (2000). International Journal of Earth Sciences, 89(3), 450-460.</p><p>[3] Prémaillon M. (2018). Ph.D. thesis, University of Toulouse.</p><p>[4] Karátson D., Favalli M., Tarquini S., Fornaciai A., Wörner G. (2010). Journal of Volcanology and Geothermal Research, 193, 171-181.</p><p>[5] Favalli M., Karátson D., Yepes J., NannipierI L. (2014). Geomorphology, 221, 139-149.</p><p>[6] Lahitte P., Samper A., Quidelleur X. (2012). Geomorphology, 136, 148-164.</p><p>[7] Karátson D., Yepes J., Favalli M., Rodríguez-Peces M.J., Fornaciai A. (2016). Geomorphology, 253, 123-134.</p>

scholarly journals Numerical Investigation of Hydrodynamics and Cohesive Sediment Transport in Cua Lo and Cua Hoi Estuaries, Vietnam

2021 ◽  
Vol 9 (11) ◽  
pp. 1258
Author(s):  
Viet Thanh Nguyen ◽  
Minh Tuan Vu ◽  
Chi Zhang
Keyword(s):  
Sediment Transport ◽  
Great Influence ◽  
Wave Model ◽  
Sediment Concentration ◽  
Wave Climate ◽  
Cohesive Sediment ◽  
Wave Direction ◽  
The South ◽  
The North ◽  
Cohesive Sediment Transport

Two-dimensional models of large spatial domain including Cua Lo and Cua Hoi estuaries in Nghe An province, Vietnam, were established, calibrated, and verified with the observed data of tidal level, wave height, wave period, wave direction, and suspended sediment concentration. The model was then applied to investigate the hydrodynamics, cohesive sediment transport, and the morphodynamics feedbacks between two estuaries. Results reveal opposite patterns of nearshore currents affected by monsoons, which flow from the north to the south during the northeast (NE) monsoon and from the south to the north during the southeast (SE) monsoon. The spectral wave model results indicate that wave climate is the main control of the sediment transport in the study area. In the NE monsoon, sediment from Cua Lo port transported to the south generates the sand bar in the northern bank of the Cua Hoi estuary, while sediment from Cua Hoi cannot be carried to the Cua Lo estuary due to the presence of Hon Ngu Island and Lan Chau headland. As a result, the longshore sediment transport from the Cua Hoi estuary to the Cua Lo estuary is reduced and interrupted. The growth and degradation of the sand bars at the Cua Hoi estuary have a great influence on the stability of the navigation channel to Ben Thuy port as well as flood drainage of Lam River.

Investigation of long-term changes of coastal wave directionality patterns and their connections with NAO climatic index: UK case study

2021 ◽  
Author(s):  
Antonia Chatzirodou
Keyword(s):  
Climate Change ◽  
Flood Risk ◽  
Wave Climate ◽  
Wave Direction ◽  
Climatic Index ◽  
Coastal Flood ◽  
Time Period ◽  
Wave Directionality ◽  
Coastal Flood Risk ◽  
Offshore Wave

<p>The effects of climate change are at the spotlight of scientific research. In coastal science the effects of sea-level rise (SLR) on coastal areas, mainly as a result of melting of ice sheets and thermal volume expansion consist an intensive area of research. As well the changing ocean wave field due to greenhouse effect and interactions of atmospheric processes is under investigation. Researchers have placed focus on significant wave height changes and their associated impacts on the coastal environment, with evidence suggesting that the number, intensity and location of storms will change. It is suggested that equal attention should be placed on the mean wave direction changes and the effects that these changes may have on the coastlines and surrounding coastal infrastructure. Following that, this study investigated the changes in wave direction data since 1979 to 2019 covering 40 years’ time period at 11 offshore UK coastal locations. The selected locations lie close to WaveNet, Cefas’ strategic wave monitoring network points for the UK. Stakeholders use the data to provide advice and guidance to all involved parties including responders and communities about coastal flood risk. On a longer timescale the data provide evidence to coastal engineers and scientists of the wave climate change patterns and the implications this may have on coastal structures and flood defences design. Based on this initiative, this study investigated UK offshore wave climate changes by performing a longer timescale analysis of changes of wave direction patterns. The wave direction data were taken from ECMWF ERA5 6-hour hind cast data catalogue which covers 40 years’ time period from 1797-2019 (Copernicus Climate Change Service (C3S), 2017). MATLAB software coding was primarily utilized for data processing and analyses. Following that, inferential statistics were applied to map inter-decadal statistical changes in wave direction patterns, suggesting that wave directionality patterns have presented changes at 11 offshore locations tested.  The connections of wave directions with North Atlantic Oscillation (NAO) Climatic Index are currently investigated through use of machine learning approaches. The results of this study can be confidently used in wave transformation computational models coupled with hydro-morphodynamic models to downscale offshore wave direction changes to UK coastal areas. This can help identify susceptible coasts to offshore wave climate change. Susceptibility is regarded in form of coastal erosion and accretion rates changes as a result of altered offshore wave conditions, which might affect coastal flood risk with potential impacts on critical infrastructure.  </p>

scholarly journals Trend analysis of wave storminess: wave direction and its impact on harbour agitation

2010 ◽  
Vol 10 (11) ◽  
pp. 2327-2340 ◽  
Author(s):  
M. Casas-Prat ◽  
J. P. Sierra
Keyword(s):  
Energy Content ◽  
Temporal Trends ◽  
Wave Climate ◽  
Maximum Energy ◽  
Wave Direction ◽  
The South ◽  
Wave Hindcast ◽  
Catalan Coast ◽  
Northwestern Mediterranean Sea

Abstract. In the context of wave climate variability, long-term alterations in the wave storminess pattern of the Catalan coast (northwestern Mediterranean Sea) are analysed in terms of wave energy content and wave direction, on the basis of wave hindcast data (from 44-year time series). In general, no significant temporal trends are found for annual mean and maximum energy. However, the same analysis carried out separately for different wave directions reveals a remarkable increase in the storm energy of events from the south, which is partly due to a rise in the annual percentage of such storms. A case study of Tarragona Port (on the southern Catalan coast) highlights the importance of including changes in wave direction in the study of potential impacts of climate change. In particular, an increase in the frequency of storms from the south leads to greater agitation inside the Port.

scholarly journals Climate-induced variability in South Atlantic wave direction over the past three millennia

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
A. P. Silva ◽  
A. H. F. Klein ◽  
A. F. H. Fetter-Filho ◽  
C. J. Hein ◽  
F. J. Méndez ◽  
...  
Keyword(s):  
Global Climate ◽  
Southern Annular Mode ◽  
Wave Climate ◽  
Wave Generation ◽  
South Atlantic ◽  
Wave Direction ◽  
Global Climate Changes ◽  
Ocean Wave Climate ◽  
Forcing Mechanisms

Abstract Through alteration of wave-generating atmospheric systems, global climate changes play a fundamental role in regional wave climate. However, long-term wave-climate cycles and their associated forcing mechanisms remain poorly constrained, in part due to a relative dearth of highly resolved archives. Here we use the morphology of former shorelines preserved in beach-foredune ridges (BFR) within a protected embayment to reconstruct changes in predominant wave directions in the Subtropical South Atlantic during the last ~ 3000 years. These analyses reveal multi-centennial cycles of oscillation in predominant wave direction in accordance with stronger (weaker) South Atlantic mid- to high-latitudes mean sea-level pressure gradient and zonal westerly winds, favouring wave generation zones in higher (lower) latitudes and consequent southerly (easterly) wave components. We identify the Southern Annular Mode as the primary climate driver responsible for these changes. Long-term variations in interhemispheric surface temperature anomalies coexist with oscillations in wave direction, which indicates the influence of temperature-driven atmospheric teleconnections on wave-generation cycles. These results provide a novel geomorphic proxy for paleoenvironmental reconstructions and present new insights into the role of global multi-decadal to multi-centennial climate variability in controlling coastal-ocean wave climate.

scholarly journals Development of a global dataset of Wetland Area and Dynamics for Methane Modeling (WAD2M)

2020 ◽  
Author(s):  
Zhen Zhang ◽  
Etienne Fluet-Chouinard ◽  
Katherine Jensen ◽  
Kyle McDonald ◽  
Gustaf Hugelius ◽  
...  
Keyword(s):  
Land Surface ◽  
Large Scale ◽  
Southern Oscillation ◽  
Microwave Remote Sensing ◽  
Global Scale ◽  
Annual Maximum ◽  
Time Step ◽  
Wetland Area ◽  
Wetland Extent

Abstract. Seasonal and interannual variations in global wetland area is a strong driver of fluctuations in global methane (CH4) emissions. Current maps of global wetland extent vary with wetland definition, causing substantial disagreement and large uncertainty in estimates of wetland methane emissions. To reconcile these differences for large-scale wetland CH4 modeling, we developed a global Wetland Area and Dynamics for Methane Modeling (WAD2M) dataset at ~25 km resolution at equator (0.25 arc-degree) at monthly time-step for 2000–2018. WAD2M combines a time series of surface inundation based on active and passive microwave remote sensing at coarse resolution (~25 km) with six static datasets that discriminate inland waters, agriculture, shoreline, and non-inundated wetlands. We exclude all permanent water bodies (e.g. lakes, ponds, rivers, and reservoirs), coastal wetlands (e.g., mangroves and sea grasses), and rice paddies to only represent spatiotemporal patterns of inundated and non-inundated vegetated wetlands. Globally, WAD2M estimates the long-term maximum wetland area at 13.0 million km2 (Mkm2), which can be separated into three categories: mean annual minimum of inundated and non-inundated wetlands at 3.5 Mkm2, seasonally inundated wetlands at 4.0 Mkm2 (mean annual maximum minus mean annual minimum), and intermittently inundated wetlands at 5.5 Mkm2 (long-term maximum minus mean annual maximum). WAD2M has good spatial agreements with independent wetland inventories for major wetland complexes, i.e., the Amazon Lowland Basin and West Siberian Lowlands, with high Cohen's kappa coefficient of 0.54 and 0.70 respectively among multiple wetlands products. By evaluating the temporal variation of WAD2M against modeled prognostic inundation (i.e., TOPMODEL) and satellite observations of inundation and soil moisture, we show that it adequately represents interannual variation as well as the effect of El Niño-Southern Oscillation on global wetland extent. This wetland extent dataset will improve estimates of wetland CH4 fluxes for global-scale land surface modeling. The dataset can be found at http://doi.org/10.5281/zenodo.3998454 (Zhang et al., 2020).

COASTAL MODELING FOR REGIONAL SEDIMENT BUDGET IN WEST MAUI, HAWAII

2017 ◽  
pp. 14
Author(s):  
Lihwa Lin ◽  
Zeki Demirbilek ◽  
Jessica Podoski ◽  
Thomas Smith ◽  
Lihwa Lin
Keyword(s):  
Sediment Transport ◽  
Wave Breaking ◽  
Wave Climate ◽  
Mountainous Terrain ◽  
The West ◽  
Coastal Modeling ◽  
Eddy Formation ◽  
Coastal Margin ◽  
Limited Supply ◽  
Offshore Wave

The West Maui Region incorporates a thin coastal margin backed by steep mountainous terrain that has been vastly altered by agricultural and urbanized development. Coastline includes headlands and reefs with a very limited supply of sediment. Shoreline was found to be erosional chronically based on average rates. The dynamics of the area are complex with a wave climate affected by intricate bathymetry, wind, and island sheltering. Longshore currents vary locally and temporally from nearshore to offshore. Wave and current modeling indicates that large waves in the summer and winter have driven the majority of sediment transport along the coast. The littoral transport is essentially northward in summer and southward in winter. The net transport of longshore sediment is overall small. The nearshore eddy formation with wave breaking nearshore over narrow sandy bed and wide reefs may increase the complexity of sediment movement within the region.

scholarly journals Interannual Response of Reef Islands to Climate-Driven Variations in Water Level and Wave Climate

2020 ◽  
Vol 12 (24) ◽  
pp. 4089
Author(s):  
Michael V. W. Cuttler ◽  
Kilian Vos ◽  
Paul Branson ◽  
Jeff E. Hansen ◽  
Michael O’Leary ◽  
...  
Keyword(s):  
Climate Change ◽  
Coral Reef ◽  
Southern Oscillation ◽  
Wave Climate ◽  
Water Levels ◽  
Short Term ◽  
Island Evolution ◽  
Reef Islands ◽  
Wave Conditions

Coral reef islands are among the most vulnerable landforms to climate change. However, our understanding of their morphodynamics at intermediate (seasonal to interannual) timescales remains poor, limiting our ability to forecast how they will evolve in the future. Here, we applied a semi-automated shoreline detection technique (CoastSat.islands) to 20 years of publicly available satellite imagery to investigate the evolution of a group of reef islands located in the eastern Indian Ocean. At interannual timescales, island changes were characterized by the cyclical re-organization of island shorelines in response to the variability in water levels and wave conditions. Interannual variability in forcing parameters was driven by El Niño Southern Oscillation (ENSO) cycles, causing prolonged changes to water levels and wave conditions that established new equilibrium island morphologies. Our results present a new opportunity to measure intermediate temporal scale changes in island morphology that can complement existing short-term (weekly to seasonal) and long-term (decadal) understanding of reef island evolution.

scholarly journals A LONG-TERM EQUILIBRIUM BEACH PLANFORM MODEL FOR COASTAL WORK DESIGN

2012 ◽  
Vol 1 (33) ◽  
pp. 43 ◽  
Author(s):  
Verónica Cánovas ◽  
Raúl Medina
Keyword(s):  
Sediment Transport ◽  
Case Studies ◽  
Wave Height ◽  
Surf Zone ◽  
Control Point ◽  
Wave Climate ◽  
Work Design ◽  
Sediment Distribution ◽  
Wave Incidence

Traditional models usually allow fitting the equilibrium beach planform of crenulated beaches knowing wave climate characteristics at a control point. However, sometimes there are shoals or bars in the surf zone which affect surf zone dynamics and longshore sediment distribution, and it is difficult to take into account these elements using those traditional models. A long-term equilibrium beach planform model is proposed here based on sediment transport equations. This model takes into account the sediment transport due to oblique wave incidence and that due to wave height gradient. Two case studies have been studied: a simple pocket beach and a beach which is sheltered by a sandstone bar. Results show the model fits reasonably well the equilibrium beach planform to the shorelines of those beaches. This model is more suitable than traditional models when there are elements affecting surf zone dynamics.

Temporal and spatial variability of the open coast wave climate of Victoria, Australia

2020 ◽  
Vol 71 (3) ◽  
pp. 394 ◽  
Author(s):  
S. L. McSweeney
Keyword(s):  
Wave Height ◽  
East Coast ◽  
Southern Oscillation ◽  
Southern Annular Mode ◽  
Wave Climate ◽  
Strong Positive Correlation ◽  
Wave Direction ◽  
The West ◽  
Open Coast ◽  
Wave Conditions

The open coast of Victoria, Australia, is one of the highest wave energy coastlines globally. Despite this, a lack of permanently deployed wave buoys has limited prior analysis of wave conditions. In this study, the wave climate of Victoria was analysed using 31 years of directional data hindcast from the National Oceanic and Atmospheric Administration’s WaveWatch-III model (Climate Forecast System Reanalysis hindcasts). An eastward decrease in wave height and period occurs from Portland to Wilson’s Promontory. This trend then reverses on the east coast. Across the west and central coasts, wave direction is dominated by south-west swells as influenced by strong westerly winds and mid-latitude low-pressure systems. On the east coast, wave direction becomes more variable, with added southerly, south-east and easterly components. The Southern Annular Mode influences wave climate variability on the west coast and is negatively correlated with storm frequency and wave direction. On the east coast, the El Niño–Southern Oscillation showed a strong positive correlation with wave height and a negative correlation with direction. This work provides a benchmark to compare to future changes. It will inform a higher-resolution analysis of the spatial correlation of wave conditions with climate processes to predict shoreline response.

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