While coastal zones support economic and social development, they also face prominent contradictions between shoreline utilization and ecological protection. This study proposed an innovative conflict-coordination framework for constructing living shorelines, aiming to identify and mitigate multi-dimensional conflicts in coastal engineering. The framework introduced a four-dimensional conflict analysis structure encompassing policy, social environment, ecological environment, and technical capacity, thereby extending beyond traditional single-dimensional or ecological-only assessments. Furthermore, it integrated the Comprehensive Conflict Index (CCI) with a multi-objective coordination model that couples three core indicators (e.g., whole-life-cycle carbon emissions, comprehensive impact intensity, and the living shoreline index) to achieve synergistic optimization among lower carbon emission, less human intervention, and higher ecological function objectives. Applied to an ecological restoration and seawall ecologization project in Zhenhai District, Ningbo, the results demonstrated that the framework helped constructing living shorelines by effectively reducing comprehensive conflict intensity with 21.2%, decreasing total carbon emissions with 60.2%, and significantly improving both the living shoreline index and multi-objective coordination level. Compared to traditional coastal zone assessment methods, these findings highlighted the differentiated advantages of the proposed framework in quantifying conflict sources, enhancing coordination among multi-objectives, and providing scientific support for living shoreline construction and sustainable coastal management.

Seawalls are important infrastructure for coastal areas to resist natural disasters such as storm tides and typhoon waves. Traditional seawall construction often causes intertidal zone fragmentation and coastline hardening, which affects the ecological function of the coastline. Ecological seawalls have both functions of disaster prevention and ecology and have become an inevitable trend in seawall construction at home and abroad. However, constructing a comprehensive, scientifically rational evaluation index system for ecological seawalls is a critical and pressing challenge. This study is based on the summary of practical research on seawall construction and puts forward the connotation of ecological seawall clearly. Twenty indexes that reflect the safety, ecology and sustainability of ecological seawalls were selected, and a three-level comprehensive evaluation index system of ecological seawalls was constructed using the Analytic Hierarchy Process (AHP). Three cases, including the second stage of the ecological seawall of the large-scale narrowing project in Yuyao City, Zhejiang Province, were used in this evaluation system. The application results showed that the constructed comprehensive evaluation index system of ecological seawalls in this study has a reasonable evaluation index, and the evaluation result is reliable, which is suitable for popularization and application. This study clarifies the index system and construction method for the comprehensive evaluation of ecological seawalls, puts forward typical measures for ecological seawall construction from five aspects: shore beach protection, seawall body structure, seawall surface protection, building materials and vegetation selection, and provides theoretical and practical guidance for studying and judging the ecological problems of seawalls and guiding the construction of ecological seawalls.

As a typical ecological engineering structure, oyster reefs can weaken wave energy while providing ecological restoration functions, serving as an important component of nature-based coastal protection solutions. This study systematically investigated the wave attenuation characteristics of two types of oyster reefs—hemispherical and cage structures—through physical model experiments in a wind-wave-current flume. A total of 43 test conditions were designed for the hemispherical reef experiments to analyze the influence of relative crest freeboard, wave steepness, and reef width on the transmission coefficient. Results showed that the transmission coefficient decreases as the relative crest freeboard increases. When wave steepness exceeds a certain threshold, the transmission coefficient becomes more sensitive to changes in wave steepness. Based on the experimental data, an empirical transmission coefficient formula for hemispherical oyster reefs under regular waves was fitted. For the cage reef experiments, the empty flume control method was employed to analyze the spatial wave height variation under different filling rates. It was found that, under the deeply submerged condition, higher filling rates result in more significant wave attenuation, and the roughness dissipation effect of the reef structure is more pronounced under the deeply submerged condition than under the shallowly submerged condition. The research findings can provide experimental evidence for the configuration selection and parameter optimization of wave attenuation units at the front of coastal ecological seawalls.

Artificial seawater lakes constructed in estuarine environments are highly susceptible to the intrusion of water containing high concentrations of suspended sediment, which can degrade water quality and threaten ecosystem stability. To clarify the settling mechanisms and sedimentation efficiency under high-turbidity conditions, this study investigated the Baishawan Artificial Lake in the Jiaojiang Estuary, eastern China, through field observations, controlled still-water sedimentation experiments, and a multi-particle size sedimentation efficiency model. Field measurements revealed significant spatiotemporal variability in suspended sediment concentration (SSC), with higher SSC during spring tides than neap tides and a spatial gradient decreasing from the near-estuary zone to the artificial lake and offshore waters. Grain-size analysis showed that suspended sediment was dominated by clay and silt (>98%). Laboratory experiments indicated a two-stage settling process characterized by rapid initial sedimentation followed by gradual stabilization; under high concentration (1.32 kg/m³), SSC decreased by about 85% within 40 min due to concentration-enhanced flocculation, whereas under low-concentration conditions (0.24 kg/m³) approximately 14 h were required to reach the target concentration of 0.01 kg/m³. Model validation demonstrated that the multi-component sedimentation model effectively reproduced the temporal attenuation of SSC. Model application further suggested that when the initial SSC was 0.70 kg/m³ and the water depth was 5.7 m, the sedimentation tank could reduce the SSC to 0.01 kg/m³ within about 16–17 h, with an estimated annual sedimentation volume of ~65,000 m³ and a recommended dredging interval of five years. These results provide quantitative guidance for sedimentation tank operation and sediment management in estuarine artificial lakes and other high-turbidity coastal environments.