Response of the Bight of Benin (Gulf of Guinea, West Africa) coastline to anthropogenic and natural forcing, Part1: Wave climate variability and impacts on the longshore sediment transport

Longshore sediment transport (LST) is one of the main factors influencing coastal morphology and its comprehensive assessment constitutes a valuable input for coastal management. In this work, the concept of long-term wave systems is used to analyze the wave climate of the Uruguayan Atlantic coast with focus on its impact on LST. It is shown how LST rate estimation changes by consider wave spectral partitions, identifies which wave systems contributes most to LST and provides a more detailed insight on its intra- and inter- annual variability and its correlation with climatic indexes.Recorded Presentation from the vICCE (YouTube Link):

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Sea wave propagation from offshore to Maputo's coast. Application to longshore sediment transport assessment

Water Science & Technology ◽

10.2166/wst.2014.162 ◽

2014 ◽

Vol 69 (12) ◽

pp. 2438-2445

Author(s):

Cristina N. A. Viola ◽

Manel Grifoll ◽

Jaime Palalane ◽

Tiago C. A. Oliveira

Keyword(s):

Wave Propagation ◽

Sediment Transport ◽

Coastal Region ◽

Wave Theory ◽

Wave Climate ◽

Linear Wave ◽

Engineering Research ◽

Longshore Sediment Transport ◽

Mesh Resolution ◽

Offshore Wave

This study aims to characterize the wave climate near the coastal region of Maputo (Mozambique), and to provide a first assessment of the sediment transport load in this area. A time-series of 13 years' worth of offshore wave data, obtained from reanalysis products, was propagated to the coast. Wave propagation was performed using Linear Wave theory and the numerical model, Simulating WAves Nearshore (SWAN). Propagations with SWAN were carried out considering different scenarios in order to evaluate the influence of parameters such as wind, tidal level, frequency spectrum and numerical mesh resolution on wave characteristics along the coast. The prevalent waves propagated came from between east and southwest directions. Results from linear propagation were used to estimate the potential longshore sediment transport. The Coastal Engineering Research Center formula was applied for a stretch of beach in the Machangulo Peninsula. A net potential rate of longitudinal sediment transport (of the order of 105 m3/year, along an extension of the coast of 21 km) was directed northwards, and was consistent with the frequent wave directions.

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LONG-TERM PREDICTION OF LONGSHORE SEDIMENT TRANSPORT IN THE CONTEXT OF CLIMATE CHANGE

Coastal Engineering Proceedings ◽

10.9753/icce.v36v.papers.15 ◽

2020 ◽

pp. 15

Author(s):

Amin Reza Zarifsanayei ◽

Amir Etemad-Shahidi ◽

Nick Cartwright ◽

Darrell Strauss

Keyword(s):

Climate Change ◽

Sediment Transport ◽

Climate Change Impacts ◽

Baseline Period ◽

Wave Climate ◽

Total Uncertainty ◽

Longshore Sediment Transport ◽

Coastal Sediment Transport ◽

Wave Energy Flux

Due to climate change impacts on atmospheric circulation, global and regional wave climate in many coastal regions around the world might change. Any changes in wave parameters could result in significant changes in wave energy flux, the patterns of coastal sediment transport, and coastal evolution. Although some studies have tried to address the potential impacts of climate change on longshore sediment transport (LST) patterns, they did not sufficiently consider the uncertainties arising from different sources in the projections. In this study, the uncertainty associated with the choice of model used for the estimation of LST is examined. The models were applied to a short stretch of coastline located in Northern Gold Coast, Australia, where a huge volume of sediment is transported along the coast annually. The ensemble of results shows that the future mean annual and monthly LST rate might decrease by about 11 percent, compared to the baseline period. The results also show that uncertainty associated with LST estimation is significant. Hence, it is proposed that this uncertainty, in addition to that from other sources, should be considered to quantify the contribution of each source in total uncertainty. In this way, a probabilistic-based framework can be developed to provide more meaningful output applicable to long-term coastal planningRecorded Presentation from the vICCE (YouTube Link): https://youtu.be/3CGU9RcGYjE

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Morphodynamics and Evolution of Estuarine Sandspits along the Bight of Benin Coast, West Africa

Water ◽

10.3390/w13212977 ◽

2021 ◽

Vol 13 (21) ◽

pp. 2977

Author(s):

Stephan Korblah Lawson ◽

Hitoshi Tanaka ◽

Keiko Udo ◽

Nguyen Trong Hiep ◽

Nguyen Xuan Tinh

Keyword(s):

Sediment Transport ◽

West Africa ◽

Large Scale ◽

River Mouth ◽

Storm Surges ◽

Longshore Sediment Transport ◽

Standards Of Living ◽

Estuarine Systems ◽

Study Sites

It is well known that estuarine systems are significantly affected by hydrodynamic conditions such as river discharge, storm surges, waves and tidal conditions. In addition to this, human interferences through developmental projects have the capability of disrupting the natural morphological processes occurring at estuaries. In West Africa, the goal to improve standards of living through large-scale dam construction, offshore ports and coastal erosion countermeasures has triggered alarming changes in the morphodynamics of estuarine systems. The estuaries at the Volta River mouth (Ghana) and “Bouche du Roi” inlet (Benin), located along the Bight of Benin coast, West Africa, were selected as two case study sites to examine their long-term morphodynamics and sandspit evolution. In this study, we primarily analyzed estuarine morphology using remotely sensed images acquired from 1984 to 2020. We further estimated the longshore sediment transport for this region using results from the image analysis and the depth of active sediment motion. Our results reveal that the longshore sediment transport rates for this region are in the magnitude of 105–106 m3/year. Comparative analysis with other estuaries and sandy coasts suggests that the longshore sediment transport along this coast has one of the largest rates estimated in the world.

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