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Urban beaches, oscillating between development and protection, are more frequently and strongly affected by human activities; therefore, comprehensive and detailed studies of the geomorphological evolution of urban beaches affected by coastal engineering are imperative. Based on 769 satellite images from 1986 to 2023, this study employed a transect-focused approach to investigate the historical shoreline change of Haikou Beach, an urban beach with three nearby offshore artificial islands. The satellite-derived mean water line positions have a temporal resolution of 41 days before 2014 and 9 days after 2018, with a random error of 4.9 m, ranking among the state-of-the-art in this field. This study revealed that the constructions of Pearl Island and Millennium Island as well as five beach nourishment projects mainly exerted a positive impact on the evolution of Haikou Beach. The beach in Pearl Island’s wave shadow area may form a tombolo in a hundred years. In the context of heightened coastal engineering development, leveraging the existing large and future larger archives of satellite imagery to analyze the complex changes of urban beaches helps mitigate the absence of field data, aiding in the development of targeted beach erosion protection and remediation strategies with scientific, engineering, and societal significance.

The construction of artificial islands is a complex engineering challenge requiring precise scheduling to optimize resource utilization, manage costs, ensure safety, and minimize environmental impacts in dynamic marine settings. In this paper, we present a multi-objective artificial island construction scheduling optimization model. This model considers many crucial factors that influence artificial island construction from 5 aspects: construction time, construction cost, project quality, resource utilization efficiency, and environmental impact. To optimize the proposed model, we propose an algorithm called Multi-objective Cooperative Differential Evolution (MOCDE). MOCDE integrates Cooperative Co-evolutionary Algorithms, and Differential Evolution to efficiently obtain the optimal schedules. To explore the performance of this model and the algorithm, extensive experiments are conducted based on real-world project data. Comparing MOCDE with established algorithms, results indicate that MOCDE improvements over previous SOTA models, achieving a reduction of 0.56% in Total Time, a decrease of 0.43% in Total Cost, and an enhancement of 7.38% in Total Quality. Besides, it also could adhere to ensure the environmental requirements.

This paper presents a quantitative investigation into the hydrodynamic characteristics of a floating breakwater system encompassing an artificial floating island. The floating breakwater’s cross-section is configured as a collection of multiple buoys, with a large main horizontal cylinder and two small cylinders. A navigation channel opening is incorporated into the floating breakwater, fortified by a floating gate positioned externally. The wave patterns surrounding the floating breakwater system are simulated and analyzed using ANSYS-AQWA (R19.0) software. The research investigates the mean transmission coefficients in the area encompassed by the floating breakwaters, considering a range of influential parameters. These parameters include the dimensions of the navigation channel opening, the planar dimensions of the floating breakwater system, the type of mooring chains, as well as the incident wave height, wave period, and wave directions, among others. Additionally, this study evaluates the impact of the navigation channel’s floating gate shape on the wave dissipation performance of the floating breakwater system. An opening angle of 75° for the navigation channel has been determined as optimal, balancing wave dissipation performance with the structural complexity of the harbor gate. The ideal distance between the floating breakwater system and the central floating island is identified as 300 m. The tensioned mooring system demonstrated superior performance compared to the catenary system. Furthermore, the arc-shaped harbor gate achieved a 26% reduction in wave transmission relative to the linear gate. These findings offer practical design guidelines for improving the stability and cost-effectiveness of floating breakwater systems in open-sea environments.

A rapid development of marine infrastructures can be observed along the global coasts. Offshore wind farms, oil and gas platforms, artificial islands, aquaculture, and more, are being constructed without a proper quantification of these human activities. Therefore, effective monitoring is required to maintain transparency towards environmental standards, marine resource management, inventorying objects, and global security. This study reviews remote sensing-based approaches to offshore infrastructure detection over the past 12 years. We analyzed 89 studies from over 30 scientific journals, highlighting spatial and temporal trends, methodological approaches, and regional and thematic research foci. Our results show a significant increase in research interest, especially since 2019. Asia, and especially China, is the predominant focus region in terms of first authorship, funding, and areas of investigation. Aquaculture is the most studied infrastructure, followed by platforms, offshore wind farms, and artificial islands. Gaofen, Sentinel, and Landsat are the most used satellite sensors for detection. The apparent shift towards automated detection methods, especially Deep Learning algorithms, reflects advances in computer vision. This study highlights the key role of earth observation in the field of off-shore infrastructure detection, which can contribute towards outlining effective monitoring practices for marine activities, as well as highlighting important knowledge gaps.

Offshore artificial islands are increasingly constructed along sedimentary coasts, yet their life-cycle impacts on adjacent beaches remain poorly quantified. Here we analyze 21 years of high-frequency satellite observations to assess how the building and removal of two adjacent islands (Ridao and Yuedao) altered shoreline evolution at Riyue Beach, China. A total of 884 Landsat and Sentinel-2 images were processed with sub-pixel shoreline detection, georeferenced against a stable coastal highway and corrected for tidal elevation to derive mean water shoreline positions along 19 transects. Results show that island emplacement triggered rapid salient growth (62–86 m yr−1) opposite the structures and temporary erosion on their flanks. A full tombolo formed on the lee side of Ridao within four years. As the salient widened, the former eroding flanks switched from an “erosional shadow” to a “secondary shelter” and began to re-accrete. The study also reveals lateral coupling between the islands; combined with previous work, it encompasses a critical D/L (offshore distance/alongshore length) threshold of 0.44–0.9 for salient–tombolo formation. Rather than perpetual dredging, we recommend accepting the impending landward connection of Ridao Island. This strategy would eliminate maintenance costs and provide a practical reference for the sustainable management of artificial island shorelines.

The construction of artificial islands not only alleviates the shortage of coastal land resources but also brings new environmental problems. This study focuses on the fundamental changes in the hydrodynamic environment and sediment transport caused by the construction of artificial islands, leading to imbalances in sediment distribution and beach erosion. This article takes the coast of Riyue Bay in Hainan Province, China, as an example and uses various methods such as field surveys and model experiments to explore the evolutionary mechanism of beach landforms under the influence of artificial islands. Based on this, an adaptive “cyclic maintenance” beach restoration plan is proposed. Reasonable distribution of beach sediment is achieved through experimental verification, effectively mitigating the coastal erosion caused by the construction of artificial islands. The expected goals were achieved after 2 years of implementation of the on-site restoration project. The results of this research not only solve practical engineering problems but also provide a good reference for the restoration of similar types of coastal beaches.

Beaches are important geomorphic units shaped by land–sea interactions. Changes in their profiles and surface sediments are directly influenced by both natural processes and human activities. This study is based on continuous topographic and sediment monitoring from 2021 to 2023 on the open and sheltered beaches of Puqian Bay, Hainan Island. It investigates the interannual profile evolution and the spatiotemporal response of sediment grain size under the influence of an artificial island. The results show that the Guilinyang Beach profile is mainly characterized by seasonal erosion–accretion cycles and the seaward migration of sandbars, while the Hilton Beach profile has undergone long-term erosion. At Hilton, sediment grain size changes are strongly coupled with profile erosion and accretion. Seasonal waves drive spatial differences in both profile and grain-size variation across Puqian Bay. The artificial island has reshaped local alongshore sediment transport and wave energy distribution. This has led to continuous erosion and coarsening in the open sector, while the sheltered sector remains morphologically stable. These findings reveal the spatiotemporal response patterns of headland-bay beaches under both natural and anthropogenic forcing, and provide scientific evidence for understanding coastal sediment dynamics and the impacts of artificial structures.

Artificial island-type reclamation often exerts certain impacts on near-shore sandy shoreline resources and coastal ecological landscapes. The relationship between artificial islands and offshore beach evolution has attracted considerable attention in coastal protection and engineering construction. In this study, we consider Hongtang Bay in Hainan Province, China, as the research object. We adopted the Gao-Collins model to investigate the substrate transport trend in this sea area based on the analysis of the measured hydrologic and sediment data. The shore section from Nanshanjiao to Hongtangling (Taling), including the flat and straight shore sections, is dominated by the lateral transport trend of the vertical shore. The near-shore water has a strong lateral sediment transport capacity, while the outer deep-water area exhibits a sediment transport trend consistent with the tidal current movement. Using multi-year topographic data, the shoreline and seabed alterations in Hongtang Bay were analyzed, and the LITLINE beach evolution model was adopted to simulate the effects of three artificial island layouts with different island filling areas, offshore distances, and plan forms on the near-shore shoreline deformation. The results obtained indicate that the artificial island arrangement with a large offshore distance and a small area has relatively substantial advantages, such as minimizing the adverse effects of artificial island implementation on the near-shore beach.

According to the characteristics of water flow movement in the junction area of island and tunnel, the \"asymmetric\" type double diversion dike measures for the north and south sides of basement shelter area were formulated. The 3D mathematical model of flow in the water area of local sinking base was established in this article. The hydrodynamic simulation of the diversion dike was carried out. The results showed that the flow velocity in shelter area of basement is greatly reduced. The maximum flow velocity of artificial flattening section of E33 pipe joint base is less than 0.5 m/s, and the maximum flow velocity of flattening ship construction section is not more than 0.8 m/s. The flow rate can meet the conditions of immersed tube installation. For safety reasons, E33 pipe joint placement time is suitable for the small tide period with weaker power flow.

Artificial floating islands (AFIs) have been documented as an efficient, environmentally friendly, and cost-effective solution to address nutrient pollution. However, most AFI studies to date have been conducted in controlled experiments, and AFI applications in natural settings, particularly in the U.S. Midwest, are limited. Here, we present the results of a combination of field and mesocosm experiments with two native aquatic plant species (Carex comosa and Eleocharis palustris) in a constructed wetland in north-central Ohio. Results showed that C. comosa outperformed E. palustris with respect to biomass accumulation and root system development. In natural conditions, C. comosa had a total dry biomass production of 58.5 ± 22.2 g/plug compared to 6.1 ± 3.2 g/plug in E. palustris. The maximum estimated mean nutrient storage for C. comosa was 20.24 g/m2 of N and 1.33 g/m2 of P, whereas it was 2.31 g/m2 of N and 0.17 g/m2 of P for E. palustris. In addition, the more developed root system of C. comosa suggests that AFIs containing this plant have better total nutrient removal capacity. The growth conditions of both species were significantly impacted by seasonal dynamics with respect to their biomass production and root elongation, as evidenced by reduced growth towards the end of the growing season.