Study on the Geo-Environmental Evolution of the Laolonggou Lagoon Under the Impacts of the Caofeidian Reclamation Projec
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Study on the Geo-Environmental Evolution of the Laolonggou Lagoon Under the Impacts of the Caofeidian Reclamation Project in Hebei Province YIN Cong1), 3), YE Siyuan2), 4), FENG Xiuli1), *, and YIN Yanhong2), 4) 1) Key Laboratory of Submarine Geosciences and Prospecting Techniques, Ministry of Education and College of Marine Geosciences, Ocean University of China, Qingdao 266100, China 2) Key Laboratory of Coastal Wetland Biogeosciences, China Geological Survey, Qingdao 266071, China 3) North China Sea Bureau, Ministry of Natural Resources, Qingdao 266033, China 4) Qingdao Institute of Marine Geology, China Geological Survey, Qingdao 266071, China (Received June 27, 2019; revised October 14, 2019; accepted December 25, 2019) © Ocean University of China, Science Press and Springer-Verlag GmbH Germany 2020 Abstract The Caofeidian Reclamation Project has been the biggest reclamation project in China so far, in which 310 km2 sea areas were reclaimed along the coast of Hebei Province, and it also bring about many problems and defects for large reclaiming area. The study focuses on the influences of the engineering exerted on evolution of the Laolonggou Lagoon with the methods of topographical measurement and surface sediment analysis. The results demonstrate that the topographical changes in the Laolonggou Lagoon had been controlled obviously by the engineering at three stages. Besides, blocking and reopening of the shoal tidal channel also affected the geological environment of the lagoon area. In the aspect of topographical change, the Laolonggou Inlet first experienced deposition after the shoal tidal channel was blocked, followed by short-time eroding for quarrying and cofferdam construction in the east, then depositing slowly after the reclaiming activity ceased, and finally eroding after the shoal tidal channel was reopened. The project, particularly cofferdam construction led to the movement of the Laolonggou Inlet axis from west to east for 50 – 100 m. In the aspect of sediment variation, the reclamation project and hydrodynamic change resulted in the variation in compositions and distribution pattern. The western lagoon area has become land mainly constituted by silt, while the sediments in the eastern area have turned finer in size. After the shoal tidal channel was reopened, the current velocity in the Laolonggou Inlet has been enhanced, making the sediments at the bottom become coarser. The sediments around the Caofeidian foreland went through a process of changing in grain size from fine to coarse and back to fine again, and the sediments are mainly constituted by silt at present. Key words
Laolonggou Lagoon Inlet; topographical evolution; Caofeidian Reclamation Project; shoal tidal channel
1 Introduction 1.1 Caofeidian Reclamation Project The Caofeidian Reclamation Project, whose working area is located on the Caofeidian shoal, the coast of Tangshan city in Hebei Province, has been the largest reclamation project in China so far. It was almost finished with 310 km2 sea area reclaimed, actually 230 km2 if
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