Abstract
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.
Highlights
The sandbar-lagoon is a typical coastal accumulation landform body composed of three geomorphic units: sandbar, lagoon and tidal inlet, and is widely found in estuaries and other coastal areas with abundant sediment sources
Based on high-resolution remote sensing images, this paper studied the geomorphological evolution of the FESL for the first time, quantified the changes in geomorphic parameters of the FESL in the past ten years, clarified the response of coastal engineering to geomorphic parameters, and revealed the reasons for the rapid extension and significant retreat of sandbar combined with the calculation of coastal sediment transport
The remote sensing images were interpreted to obtain the change in head position from 2010 to 2021 (Figure 4A)
Summary
The sandbar-lagoon is a typical coastal accumulation landform body composed of three geomorphic units: sandbar, lagoon and tidal inlet, and is widely found in estuaries and other coastal areas with abundant sediment sources. The sandbar-lagoon coast has a typical sandy coastal ecosystem, offers unique landscape and scientific research value, and plays an important role in coastal protection, ecological balance and coastal landscape beautification. Lagoon coasts are widely distributed throughout the world [1]. China, they are mainly found in Guangxi, Guangdong, Zhejiang, Liaoning, the Shandong. Coastal lagoons in China are numerous in number and type [3]. High-intensity coastal development in recent decades has subjected China’s lagoon coasts to varying degrees of damage [4].
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