The Rapidly Evolving Fudu Estuary Sandbar Lagoon Landform on the East Coast of the Bohai Sea: Recent Changes and Mechanism

The Fudu Estuary Sandbar Lagoon is one of the most representative sandbar-lagoon landforms in China, and has undergone drastic evolution in recent years, accompanied by increased coastal engineering activities. The evolution process and its control factors are studied through remote sensing interpretation and coastal sediment transport calculations. During 2010–2021, the sandbar quickly extended at an average speed of 49.5 m/a, but the annual growth has shown a decreasing trend in both area and width, and the shoreline has retreated by 25–45 m. The recent changes are the result of the combined action of natural conditions and human activities. Coastal sediment transport from west to east under the action of W-oriented waves is the natural cause of extension. An estuary dam and artificial island block the sediment transport path, and the material for the new growth of the sandbar comes from the erosion of its west side, which has directly caused the retreat and narrowing of the sandbar. The reduction in sediments from the river further aggravates the shrinkage. It is predicted that the sandbar will continue its eastward extension to connect with the coast in about 2–3 years. The erosion status is unlikely to change before the sediment supply is restored. Measures such as dismantling the estuary dam are recommended.

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

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

Analisis sedimen dan pengaruhnya terhadap kondisi garis pantai di kawasan pantai timur Kabupaten Lampung Selatan

The erosion and sedimentation process that occurred in the east coast of South Lampung is a natural process affecting the balance of coastal sediment transport and resulting in the instability of coastal lines to the loss of the coastal communities along the coast, such as silting the river and can disturb the traffic of fishing boats. This is seen as a natural process influenced by the magnitude of wave energy coming, the type and size of sediment deposited, and coastal morphology. This research aims to analyze sediment and its effect on the changing coastline. The calculation approach with the empirical formula against coastal sediment data and wave data is used to predict the natural processes occurring along the coast. Analysis of SPOT 6/7 satellite imagery years 2008, 2013, 2016, and 2018 is the next step to estimate the similarity with empirical calculation results. The results showed that the East Coast had a characteristic mud sediment size ranging from 0.0258 – 0033 mm with the highest wave from the east with a wave height above 2.57 m and a period above 8,015 S. Research locations tend to undergo sedimentation processes that are influenced by waves, grain size, and there are rivers carrying sediments and deposits in the river estuary.