The response of beach sedimentary geomorphology to consecutive storms is a complex process, especially for beaches surrounding an island. Variations in coastal sedimentary landforms, dynamic environments and levels of development and utilization lead to non-uniformity in storm response, which may become more pronounced when influenced by continuous storms. This study focuses on the beaches around Weizhou Island to investigate this non-uniformity. Based on the topographic, surface sediment and hydrodynamic data collected on site before and after the consecutive typhoons (Typhoons Lionrock and Kompasu), the study examines the characteristics of beach geomorphology and surface sediment. The results show significant differences in the geomorphological responses between the four zones along the island. On the plane, the deposition degree of Zone I beach gradually weakened from west to east, and most areas of Zone III beach appeared in an alternating state of erosion and deposition. The beaches of Zone II and Zone IV showed the characteristics of dramatic changes in the northern and central beaches and relatively stable in the southern beaches. On the profile, the beach deformation area mainly occurs in the middle and upper parts of foreshore and berm. The response intensity of beaches in zone I is the weakest, the response intensity of beaches in zone III is the most intense, and the response intensity of beaches in zone II and zone IV is relatively close. However, the performance of beach sediments in different regions before and after continuous typhoons is less different. Except that the beach sediments in Zone I were mainly refined, the beach sediments in other zones of Weizhou Island were relatively coarse, and the sediments in the middle and upper parts of the foreshore were the coarsest, with the sorting being the worst. The different combinations of incident waves and storm surges during the typhoons are the primary factors that lead to various geomorphological responses in different zones. The antecedent beach status, distributions of rock and coral reefs, and anthropogenic activities further exacerbate these differences. This work can provide reference for island beach protection and management.

Submerged artificial sandbars (SABs) are increasingly favored as an efficient method for beach nourishment, helping to mitigate beach erosion and maintain the sediment transport budget, thus promoting ecological stability. A comprehensive understanding of the morphodynamical evolution of the submerged artificial sandbar-beach profile is essential. This study employs a scaled-down moving-bed flume test to examine the dynamic geomorphological evolution of the submerged artificial sandbar-beach system under regular wave conditions. Twenty experiments, each with different wave heights and periods representative of the Zhejiang coast, were conducted. The study investigated the profile evolution and wave parameters of the submerged artificial sandbar-beach model. The results reveal low wave reflection in front of the sandbar, indicating that under the tested wave conditions, the sandbar primarily serves as a sediment source rather than effectively reflecting wave energy. In all scenarios, the top of the sandbar migrates shoreward, and the sandbar’s contour shape becomes asymmetric. For smaller wave periods, localized erosion occurs in the troughs, while larger periods result in complete siltation. Continuous sediment transport into the trough characterizes the beach face, with sediment movement controlled by wave height and period. A linear or nonlinear relationship between sandbar erosion depth, beach slope, and wave parameters (height, period) is established, providing an empirical model for SAB-beach profiles. These findings enhance the understanding of SAB-beach systems and offer valuable insights for coastal protection and disaster prevention in engineering applications.

Coastal changes in China, notably in the Zhoushan Islands, have primarily been driven by coastal reclamation since the establishment of New China. This study conducted a comprehensive analysis of the Zhoushan Archipelago shoreline spanning four decades, employing remote sensing, aerial photographs, and shoreline data since 1984, along with GIS (Geographic Information System) technology. We assessed shoreline changes using the shoreline change index and shoreline artificialization index, as well as examined the influence of the Yangtze River’s suspended sediment and impoldering activities on Zhoushan’s shoreline. Furthermore, the correlation between local economic development and shoreline development was explored. The results revealed the following key findings: (1) From 1984 to 2018, the Zhoushan Archipelago shoreline decreased by 7.05 km. Temporally, the shoreline change index was −0.08%, with the most significant reduction occurring between 2008 and 2018. Spatially, differences among island groups were not pronounced. (2) The shoreline diversity index consistently increased, indicating greater diversity and complexity in shoreline use over the four decades. (3) The shoreline artificiality index steadily rose, particularly after 2000. It was highest in the south, followed by the center, and lowest in the north. (4) The intensity index of coastal land use continuously increased, with the southern island group having a higher index compared to the Zhoushan Islands. (5) The Yangtze River contributed significantly to sand inflow, influencing shoreline changes and beach shaping in Zhejiang. However, reclamation projects were identified as the primary and direct factor. (6) A positive correlation existed between Zhoushan City’s economic development and the intensity of coastal land use. This study emphasized the need for improving the control over reclamation projects and the better management of coastal protection and use. These measures could optimize resource allocation and establish a more scientific and rational coastal zone pattern.

The distribution pattern and the morphology of sandy beaches have been extensively studied, while those in turbid coastal environments near large river estuaries are still unclear. This study analyzes the distribution pattern, morphological characteristics, and influencing factors of Zhejiang sandy beaches using statistical analysis, based on field data and historical records. Results show that the mean grain size distribution of Zhejiang sandy beaches ranges from fine sand to very coarse sand, and the beach slope and sediment grain size correspond well with the wave heights in the three regions of Zhejiang. The extent of beach headlands in central Zhejiang appeared the largest, suggesting an increased susceptibility to wave erosion due to the less sheltered headlands. Most sandy beaches in Zhejiang formed on the islands and the areas far from the estuaries, showing quantity difference in beach distribution. The comparison of the regional difference in Zhejiang sandy beaches shows that embayment is the main factor affecting the beach distribution pattern and morphological characteristics. The different embayment characteristics provide the space for beach formation and the interaction with the coastal process, the sediment supply, the nearshore hydrodynamic environment, and human intervention also have influence on the morphological characteristics of Zhejiang beaches.