Analysis of coastal erosion and siltation characteristics and evolution prediction in Yazhou Bay, Sanya

Based on the geological survey data of the coastal zone from 2018 to 2022, this paper analyzes and predicts the characteristics of shoreline evolution and seabed scouring and siltation by establishing shoreline evolution models and seabed scouring and siltation models. The research results indicate that in recent years, erosion along the Yazhou Bay coast has mainly concentrated at the east side of the Yanzao River estuary and the east side of the wave barrier of the Yazhou Bay Central Fishing Port; siltation along the coast has focused on the Moon Island (artificial island) wave shadow area and the area of the Yazhou Bay Science and Technology City. Shoreline evolution predictions show that in 20 years, the maximum retreat distance of the Yazhou Bay coast will be approximately 33 m, located at the east side of the Yanzao River estuary; the maximum siltation distance will be approximately 99m, located at the west side of the Moon Island bridge. Scouring and siltation change predictions indicate that the maximum scouring intensity of the seabed is approximately 0.14 m/a, located in the outer waters of Moon Island; the maximum siltation intensity is approximately 0.07 m/a, located in the nearshore waters of the Science and Technology City. The main reason is the construction of Moon Island, the Central Fishing Port, and Nanshan Port, which have altered the local sediment transport direction and subsequently changed hydrodynamic conditions, thus affecting the overall scouring and siltation pattern.