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The Modern Yellow River Delta has a rich history of geomorphological transformations shaped by frequent avulsions and rapid progradation. However, the delta entered a phase of altered morphodynamics following the construction of the Xiaolangdi Reservoir, which fundamentally restructured sediment transport regimes and seasonal hydrological patterns. These changes have amplified challenges in predicting long-term deltaic evolution under evolving boundary conditions. The Qingshuigou Subaqueous Delta, as a major depositional zone, provides a compelling lens to examine these morphodynamic processes. However, seasonal variations in riverine sand transport fluxes driven by the water-sand regulation scheme that accompanied the construction of the Xiaolangdi Reservoir and its impact on the evolution of the delta front are particularly understudied. This study developed a simplified long-term morphodynamic model of the Qingshuigou Subaqueous Delta to investigate its response to riverine water and sediment discharges from 1997 to 2007. The findings are as follows: (1) The morphological evolution of the Qingshuigou Subaqueous delta has gradually changed from the pattern of “leading edge deposition and localized near-shore erosion” before the construction of the Xiaolangdi Reservoir to the pattern of “enhanced leading edge deposition and increased near-shore erosion” after the construction. (2) The construction of Xiaolangdi Reservoir has weakened the spatial distribution of the erosion process to a certain extent, changing the spatial distribution dominated by the erosion process (63.8% of area) before the construction to the spatial distribution dominated by the accretion process (More than 50% of area) after the construction. (3) The spatial and temporal variability of the incoming sediments leads to a significant coarsening of the grain size of the tidal flats in the southern part of the abandoned delta, which in turn maintains a relatively steady state of the shoreline variability. In contrast, the abandoned sand spit experiences severe erosion and depositional fluctuations due to intensified wave action. (4) The study emphasizes the importance of considering seasonal variations in unsteady discharge in modeling the long-term evolution of the delta. It provides new insights into the spatial and temporal differentiation of the geomorphic equilibrium of the Yellow River Delta and contributes to a broader understanding of delta evolution.

Study region: The study area is the western part of the Macau Peninsula in China, with an area of 4.06 km2. Study focus: This study developed a coupled hydrological-hydraulic model that simulates the two-dimensional (2D) surface flow and one-dimensional (1D) drain pipe flow of compound inundation. The model was applied to Macau, China, as a study area, and the typhoon Mangkhut in 2018 was used as a case study to validate the model’s performance. Simulating compound inundation scenarios of extreme rainfall and astronomical tide and exploring the influence of astronomical tide on coastal urban inundation. New hydrological insights for the region: Urban flood disasters are profoundly influenced by tidal levels, albeit the height of tides alone does not solely exacerbate the phenomenon. Rather, the phase of astronomical tides during rainfall also plays a crucial role in determining the severity of urban flooding. This research has revealed that when rainfall synchronizes with the recession phase of the spring tide, urban flooding conditions become acute, 17.66 % increase in total surface water volume for the scenario with the highest tidal level impact compared to the scenario with the lowest tidal level impact. This paper presents the response of coastal cities to the flooding process under different combined rainstorm-astronomical tide scenarios, to provide scientific guidance for disaster preparedness planning in coastal areas, and to improve the resilience of disasters.

Laizhou Bay’s coastline has undergone multiple alterations due to human activities such as land reclamation and port construction. These changes in the coastline have led to modifications in the bay’s hydrodynamic conditions, which, in turn, can impact the marine environment and potentially result in a decline in biodiversity. To date, there has been no comprehensive study focusing on the coastline changes and hydrodynamic variations in Laizhou Bay. Therefore, this study utilizes coastline and water depth data from four time points—1990, 2003, 2013, and 2023—to establish a two-dimensional tidal current model of Laizhou Bay using Delft3D. Based on the good agreement between the simulated tidal current results and the observed data, this study further investigates the changes in tidal prism and water exchange in Laizhou Bay. The results indicate that tidal currents dominate the bay, with significant influences of topographic changes on the velocity and direction of tidal flows. The Eulerian residual current velocity is substantially lower than the tidal current velocity. Both tidal and residual currents play a role in controlling the distribution of materials within Laizhou Bay. Over the past three decades (1990-2023), the tidal prism in Laizhou Bay has shown a downward trend, with the tidal prism during spring, intermediate, and neap tides in 2023 reduced by 2.03%, 6.36%, and 10.19%, respectively, compared to 1990. The water exchange capacity has also weakened, with the half-exchange time being 71 days in 1990, increasing to 73 days in 2003 and 81 days in 2013, and showing a slight increase of 1 day in 2023 compared to 2013. Thus, changes in the coastline and water depth of Laizhou Bay can alter its hydrodynamic conditions, significantly impacting the tidal prism and water exchange, leading to a decrease in tidal prism and exchange rate, an increase in the water exchange period, a slower dispersion rate of pollutants, and a reduced water environmental carrying capacity. This research provides a scientific reference for protecting the marine environment and coastal management in Laizhou Bay.

As a new type of liquid discharged into the sea, concentrated brine exhibits complex mixing and stratification patterns due to changes in its density and hydrodynamic properties. This complexity impacts salinity transmission and can result in brine intrusion disasters, directly affecting both ecosystem and human life. This research adopted brine discharge into Dingzi Bay, Shandong Peninsula, a typical estuarine bay, as a case study. 3D convective diffusion numerical simulation techniques were applied to investigate the pathways, salinity rise, impact range, and overall effects on brine dispersal in marine water environments under the combined influence of river flow and tides. The results indicated the followings: (1) Significant spatial variations were observed in flow velocities within Dingzi Bay, with higher velocities near Xiang Island (where river flow turned into the bay) and at bay mouth; (2) The brine discharge point is influenced by complex hydrographic terrain and the combined effects of river flow and tidal movements, resulting in the formation of a high salinity area at the base of the discharge point, where salinity increases by more than 4 PSU within a 100-meter radius.; (3) During high tides, high-concentration brine was clearly transported upstream along the tidal channel, with a salinity increase of ≥3psu covering an area of 5.72×104 m2, extending up to 270 m upstream and 180 m downstream. Brine discharge led to significant mixing of concentrated seawater with seawater within the bay, altering the spatial and temporal distributions of salinity in Dingzi Bay and consequently affecting local sensitive marine species and water environment safety. This study systematically investigated the process of brine discharge into the ocean and its impact range. It was found that discharging brine in areas with higher currents promotes the mixing and dispersion of brine. Additionally, a seasonal discharge plan should be established to avoid discharges during periods of low runoff (such as winter) to minimize negative impacts on aquatic ecosystems and promote the health and diversity of marine ecosystems.

Cold waves, as a common natural disaster, have a significant impact on economic development and living environment in coastal areas, especially in estuary regions. This paper utilizes the Delft3D software based on a rectangular grid, driven by the eight major tidal harmonic constituents of M2, S2, N2, K2, K1, O1, P1, and Q1, to construct a hydrodynamics and sediment numerical model. The study focuses on the morphodynamic changes in the Yellow River Delta (YRD) during a severe cold wave and strong wind event. By simulating the intense cold wave from November 28 to 30, 2022, the effects on the sedimentation in the YRD were analyzed. Results show that the cold wave process increases the water levels in the nearshore areas, with a general rise of more than 0.2 m in the YRD waters, particularly severe at the old Yellow River (YR) estuary and the northwest part of Laizhou Bay, reaching 0.25-0.35 m. This increase leads to intensified erosion and sedimentation in different areas near the YR estuary, especially near the old YR estuary and in the northwest part of Laizhou Bay. After a cold wave process, the erosion and sedimentation increase significantly by 0.05-0.1m. Furthermore, by comparing the flow speed differences and tidal-induced Eulerian residual currents with and without cold waves, it was found that around the YRD, from the current river estuary to the old YR estuary, the maximum flow speed increased by more than 0.35 m/s during the cold wave, and the maximum Eulerian residual currents also increased by 0.13 m/s. The direction of the residual currents changed from northwest-southeast to south-north, further confirming the significant impact of cold waves on the morphodynamic evolution of the YRD. This study provides new perspectives and methods for understanding and predicting morphodynamic changes in estuarine regions during cold waves, which is significant for disaster prevention, mitigation, and management of estuarine areas.

The Yellow River Delta has undergone significant changes, developing a temperate chalk-sand silty coast with expansive and level tidal flats. However, the area is currently facing the threat of erosion due to coastal area construction, decreased river sediment discharge into the sea, and intensified marine hydrodynamic forces. Remote sensing technology has important applications in spatial and temporal monitoring of tidal flats. This study employs tidal data to establish the threshold range for the extraction of tidal flats in the Yellow River Qingshuigou sub-delta, using the water frequency method based on the image element proposed by previous authors. The study successfully identifies and analyzes the range of tidal flats, and further delves into their evolutionary process and underlying mechanisms. The study concludes that the area of tidal flats has shown a decreasing trend and was divided into a “rapid decline phase” and an “overall stabilization phase” with 2006 as the boundary. The spatial and temporal evolution of tidal flats is primarily influenced by three main factors: river sediment discharges, marine hydrodynamic forces, and anthropogenic reclamation activities. Specifically, the river sediment discharges and marine hydrodynamic forces impact the extent of tidal flats by modifying the boundary conditions, primarily at the sea boundary. Reclamation activities have a direct and rapid effect on the extent of tidal flats, primarily at the land boundary. In this study, we determined the contribution of three factors to the spatial and temporal evolution of tidal flats in different periods. During the two phases of the tidal flats’ spatial and temporal evolution in the Yellow River Qingshuigou sub-delta, the driving mechanisms were identified as “reclamation - marine hydrodynamic forces - river sediment discharges” and “marine hydrodynamic forces - river sediment discharges - reclamation”.

The coastline of the Yellow River Delta has undergone continual alterations due to both natural forces and human activity. Studying these changes is crucial for promoting economic growth and preserving the region’s ecological balance. Based on imagery captured by the Landsat5 and Landsat8 satellites, this study uses statistical data from the Digital Shoreline Analysis System (DSAS), including Net Shoreline Movement (NSM), End Point Rate (EPR), and Linear Regression Rate (LRR), to analyze the changes in the Yellow River Delta coastline from 2009 to 2019. This being the case, a hydrodynamic model under different shoreline conditions was established using Delft3D to compare and analyze the impact of shoreline changes on the tidal current field. From 2009 to 2019, the coastline in the study area exhibited an average movement distance of 1285m (NSM) and an annual change rate of 127.7m/a (LRR). The average increase in the area of the current estuary was 7.68km2/a, while the average decrease in the area of the old estuary was 4.91km2/a. Shoreline evolution is primarily influenced by the influx of water and sediment into the ocean. Following the implementation of water and sediment regulation, the existing estuary’s shoreline experienced a rapid initial accumulation of silt, which subsequently decelerated over time. Conversely, the former estuary has consistently undergone erosion. The greater the change in shoreline, the closer to the coast, and the greater the change in the tide. From 2009 to 2019, flow velocity and direction in the Yellow River Delta generally showed a decreasing trend, with changes ranging from 0.34% to 25.94%. The residual flow velocity near the current estuary gradually increased by about 2cm/s, while that near the abandoned old estuary gradually decreased by about 1cm/s, with no significant changes offshore. The sediment transported by the Yellow River is deposited at the current estuary, causing the coastline to move northeastward. In the abandoned estuary, there is erosion, causing the coastline to retreat.

Gradient materials can achieve both external strengthening and internal toughening, which has great potential to break the strong plastic tradeoff. Titanium carbide (TiC) particle is conducive to form a wearable surface in biomedical Titanium (Ti) alloy. In this work, gradient TiC/Ti6Al4V composites were successfully prepared by friction stir processing (FSP). Microstructure, texture and mechanical properties of the material were systematically characterized. Scanning electron microscopy (SEM) showed that the equiaxed grains near the machined surface were transformed into elongated grains inside. The results of energy spectrum analysis (EDS) showed that there was element aggregation near TiC particles. X-ray diffraction (XRD) indicated martensitic transformation in the stir zone and in the transition zone. The results of nano indentation showed that the hardness of stir zone was higher. In order to promote recrystallization and improve the hardness of the transition zone, high temperature rapid heat treatment was carried out after FSP. When the sample was heated at 700 °C and cooled in the furnace, the hardness increased to the maximum. In the process of rapid heating, the dissolution of elements near TiC particles also led to the increase of hardness. This study provides a new idea for surface modification of gradient titanium alloy by using FSP method to improve its mechanical properties.

The switch from using only trivalent oral polio vaccine (tOPV) to sequential schedules combining inactivated poliovirus vaccine (IPV) and bivalent oral polio vaccine (bOPV) for polio vaccination will cause changes to mucosal immunity against polio in infants, which plays an important role in preventing the poliovirus spread. Here, we analyzed mucosal immunity against poliovirus in the intestine during different sequential vaccination schedules. We conducted clinical trials in Guangxi Province, China on 1,200 2-month-old infants who were randomly assigned to one of three vaccination schedule groups: IPV-bOPV-bOPV, IPV-IPV-tOPV, and IPV-IPV-bOPV, with vaccine doses administered at 8, 12, and 16 weeks of age. Stool samples were collected from 10% of participants in each group before administration of the second vaccine doses and at 1, 2, and 4 weeks after the administrations of the second and third vaccine doses. Immunoglobulin A (IgA) in the stool samples was measured to analyze the mucosal immune response in the intestine. Because of the absence of poliovirus type 2 in bOPV, the vaccination schedule of IPV-IPV-bOPV did not sufficiently raise intestinal mucosal immunity against poliovirus type 2, although some cross-immunity was seen. The level of intestinal mucosal immunity was related to shedding status; shedders could produce intestinal mucosa IgA more quickly. The intestinal mucosal immunity level was not related to serum neutralizing antibody level. In the combined sequential vaccination schedule of IPV and bOPV, the risk of circulating vaccine-derived poliovirus type 2 (cVDPV2) may be increased owing to insufficient intestinal mucosal immunity against poliovirus type 2.

Coastal areas have become the primary location for nuclear power plant sites due to the convenience of seawater cooling. In China, the diffusion range of thermal discharge water has always been a hot research topic as the basis for sea use areas. The main physical process of heat loss in the numerical simulation of thermal discharge from power plants is heat exchange between the water surface and air. Currently, the methods for calculating this heat loss include the heat flux method and the water surface heat exchange coefficient method. Taking a power plant in Zhejiang as the research object, the MIKE 3 temperature–salinity module (heat flux method) and MIKE ECO Model (water surface heat exchange coefficient method) were used for modeling, and the diffusion of thermal discharge water under different modules was compared and analyzed. The results show that the calculated area of the water temperature rise envelope between the two modules differed significantly under the same conditions. The surface 4 °C temperature rise area, as calculated using ECO Model, was 45.8% smaller than that of the temperature–salinity module. The MIKE 3 temperature–salinity module can simulate the heat accumulation of water under thermal buoyancy, producing a significant thermal stratification phenomenon; the ECO module does not accurately represent the heat exchange process between the water surface and the air, and it does not adequately capture the significant vertical stratification that occurs in real-world scenarios. On this basis, this study not only lays a foundation for further exploring the impact of thermal discharge water from this powerhouse on the structure of surrounding marine biological communities and dissolved oxygen content in water bodies but also provides scientific evidence for the selection of modules when simulating thermal discharge water with the MIKE model.

Typhoons play an important role in beach evolution. The storm surge and large waves caused by typhoons can cause significant changes in beach morphology in a short period of time. The mechanism of beach evolution and profile changes during typhoons is significantly different from that under non-typhoon dynamic conditions. The XBeach numerical model provides an effective tool for predicting the response of sandy coasts to typhoons. This study is based on field-collected long-term beach profile elevations and grain size data, which were used to establish a two-dimensional XBeach model for simulating the morphological evolution of Cudao Island Beach under Typhoon Lekima. The GSA (Generalized Sensitivity Analysis) method was used to determine the sensitivity order of several important parameters in this modeling. Four different moments of wave height variation were selected during the typhoon process to analyze and study beach evolution. The results show that Chudao South Beach is always in a state of erosion during the typhoon period. The wave water increase is apparent in the nearshore wave-breaking area. The beach shoulder in the northeastern part of the beach is short, and the profile, with a short length, responds quickly to the typhoon. The eroded sediment is mainly deposited in the lower part of the intertidal zone or even transported outside of the wave-breaking zone, and a small part is transported to the shore and deposited in the high-tide zone. The continuous sediment transport along the coast of Chudao Beach is an important factor that influenced the evolution of each profile during Typhoon Lekima.

In recent years, the Global Polio Eradication Initiative has gradually implemented a global shift in polio immunization programs. Few studies cover polio immunization program impacts on the efficacy of other vaccines. This study investigated whether polio immunization programs affected hepatitis A (HepA) and hepatitis B (HepB) vaccination efficacy. Serum samples were collected from 968 infants before the first dose of polio vaccine, 28 days after completing primary polio immunization, and at 24 months old. Infants were classified into six polio immunization program groups: 1sIPV+2bOPV, 2sIPV+1bOPV, 2sIPV+1tOPV, 1cIPV+2bOPV, 2cIPV+1bOPV, and 2cIPV+1tOPV (sIPV: Sabin inactivated poliovirus vaccine; cIPV: Salk inactivated poliovirus vaccine; b, bivalent; t, trivalent; OPV, oral polio vaccine). No significant differences existed in antibody titers against HepA virus (anti-HAV) among the polio immunization program groups at any of the three time points (pre-first dose [p = 0.412], 28 days after primary immunization [p = 0.676], 24 months old [p = 0.556]). Before the first dose (p = 0.178) and at age 24 months (p = 0.987), no significant differences existed in HepB surface antibody (HBsAb) titers between the six polio immunization program groups). Twenty-eight days after primary immunization, no significant difference existed in HBsAb titers between groups after Bonferroni correction. Following HepA and HepB immunization, anti-HAV and HBsAb positivity reached > 98% in all groups, reflecting effective immunization. Our data suggest that different polio immunization programs did not affect HepA and HepB vaccine efficacy; HepA and HepB vaccines maintained high effectiveness irrespective of polio immunization program. This trial was registered on Clinical Trials.gov: NCT03614702.

The evolution of renewable energy technologies may surmount fossil fuel disadvantages. Wave energy is considered one of the best alternatives to fossil energy due to its advantages. The 40-year (1979–2018) spatio-temporal distribution of wave energy is presented using European Centre for Medium-Range Weather Forecasts (ECMWF) Reanalysis v5 (ERA5) datasets. In addition, the common formula used for wave energy evaluation is derived from the linear wave theory in deep water, which is not applicable in shallow water. Therefore, a new equation that is suitable for both shallow and deep water is derived, which improves the accuracy of the wave energy evaluation for various water depths. The main aim is to investigate the spatio-temporal wave energy for offshore China from 1979 to 2018 and combine the new standard of classification to recommend the optimal area. The nearshore zone from Zhejiang province to Guandong province is considered the ideal zone, and the average annual wave energy density in this area is above 10 kW/m.

Tidal phenomenon is a significant dynamical phenomenon in the ocean, and the accurate prediction of tide is an important task for various maritime activities. This paper proposes analysis method considering tidal periodicity and apply it to the actual tide prediction. The results prove that this method can solve the delay problem in tide prediction, improve the accuracy of prediction. Compared with the tidal harmonic analysis method, the prediction result of this method is more accurate and requires less data for short-term tidal forecast. Although this study can only provide an accurate forecast for 3 days, it is enough to deal with risks. How to improve the accuracy of long-term prediction is one of the future research directions.

Functional gradient materials (FGMs), as a modern group of materials, can provide multiple functions and are able to well mimic the hierarchical and gradient structure of natural systems. Because biomedical implants usually substitute the bone tissues and bone is an organic, natural FGM material, it seems quite reasonable to use the FGM concept in these applications. These FGMs have numerous advantages, including the ability to tailor the desired mechanical and biological response by producing various gradations, such as composition, porosity, and size; mitigating some limitations, such as stress-shielding effects; improving osseointegration; and enhancing electrochemical behavior and wear resistance. Although these are beneficial aspects, there is still a notable lack of comprehensive guidelines and standards. This paper aims to comprehensively review the current scenery of FGM metallic materials in the biomedical field, specifically its dental and orthopedic applications. It also introduces various processing methods, especially additive manufacturing methods that have a substantial impact on FGM production, mentioning its prospects and how FGMs can change the direction of both industry and biomedicine. Any improvement in FGM knowledge and technology can lead to big steps toward its industrialization and most notably for much better implant designs with more biocompatibility and similarity to natural tissues that enhance the quality of life for human beings.

Design Basis Flood Level(DBFL) is one of the important parameters in nuclear power plant siting in coastal area. This paper proposes a new model of Instantaneous Sea Surface Height(ISSH) to calculate DBFL. The model is validated and compared with bivariate extreme distribution model and independent variables model, using observed series from Shidao bay in Shandong province. Results show that the model is more suitable for representing the DBFL. The joint probability model gets greater return period and smaller return level than ISSH model, because it adopts an association parameter derived from the linear correlation coefficient. Independent variables model is the most reliable in safety but wasteful in economy.

In order to have a comprehensive understanding of the water exchange capacity in Fangcheng Bay, a high-resolution numerical model named MIKE3, which is a three-dimensional hydrodynamic model, is established based on unstructured triangular grid. Using Lagrange proton tracing method, the half-exchange period and commutative law of water are selected as the evaluation indexes to evaluate the water exchange capacity of Fangcheng Bay in dry and wet seasons. The results are shown as follows: the water exchange in Fangcheng Bay is mainly controlled by runoff and tide. Due to the existence of Fangcheng River, the spatial distribution of the concentration of conservative particles in the West Bay increased from the estuary to the outside of the bay, while that in the East Bay increased from the entrance to the inside of the bay. With the increasing time, the decrease ratio of concentration in the two bays reduces. The water exchange time in West Bay is obviously shorter than that in East Bay. The half-exchange period of West Bay is 1.7 d in wet season and 3.6 d in dry season, while that in East Bay is 15.2 and 27.8 d, respectively. [ABSTRACT FROM AUTHOR]

As we know, wave significant height (Hs) and wave period, are critical for maritime commerce, infrastructure design, and hazard mitigation, etc. In this paper, we adopt wave data from eight stations in the data-sparse China Sea to assess the ERA-Interim (ERA-I). We have described the comparison with the short-scale and annual features between the datasets. The annual difference of Hs varies from –0.43 to 0.1 m with a mean value of –0.24 m for eight stations. In most of the stations, the ERA-I data of the locations except for the typhoon period has an overall overestimation, and the biases is positive. During the typhoon, due to the underestimation of the typhoon wind field, Hs in the ERA-I data is underestimated, which can be up to –50%. The physics research of typhoon is still poorly at present, causing the discrepancies between the datasets. Hence, we can’t adopt the ERA-I Hs for design applications unless the validation has been tested by specific sites. [ABSTRACT FROM AUTHOR]

Based on the observed runoff and sediment data from Lijin hydrological station during the period of 1950–2018, this paper addressed the long-term change characteristics of runoff and sediment fluxes into the sea from the Yellow River. The Mann-Kendall test was adopt to estimate the long-term trends in the runoff and sediment time series. The Mann-Whitney-Pettitt (MWP) test were used to determine the change points of runoff and sediment time series. It could be concluded that the annual runoff and the sediment fluxes decreased significantly at the rates of −6.17×109 m³/a and −0.213×109 t/a, respectively. The changes during the flood season were more dramatic than in the dry season, especially for the sediment flux. Different significant change points are detected in the runoff and sediment time series. The changing point for the runoff occurred in 1968, 1985, and 2002 and those of sediment flux in 1968, 1985, and 1996, respectively. The negative long-term change trend and the occurrence of change points are highly associated to natural variation and human activities in the Yellow River basin. The occurrence time of some change points accords even with man-made events. [ABSTRACT FROM AUTHOR]

Waves are the important driving factors that shape the estuary and coastal landscape of the Yellow River Delta (YRD). Changes in wave dynamics can affect the evolution of landforms, causing erosion or accumulation between coastal areas. In this study, the variation in suspended sediment concentration in the Yellow River under different seawater conditions is simulated based on the Delft3D. Quantitative study of the difference in ocean dynamics between the current estuary and abandoned estuary of the Qingshuigou channel in the YRD is conducted based on the difference in suspended sediment concentrations (Di), which revealed the shaping effect of tidal currents and waves in the evolution of the YRD during different periods. The results show that under multiple sediment and inflow conditions during different periods, the Di-value of the abandoned estuary and its nearshore area is generally high and positive, which indicates that the coastal dynamics of the abandoned estuary are dominated by waves. However, the distribution of Di-value in the current estuary is generally negative, indicating that the coastal dynamics of the current estuary are dominated by tidal currents. In the abandoned estuary, waves restarted and resuspended the deposited silt and clay, and they were moved away from the coast by tidal current, thus causing coastal erosion. However, due to the rapid input of a large amount of sediment in the current estuary, the tidal current could not move all of it; deposition occurred in the estuary and along both sides of the coast, extending the estuary into the sea. By comparison, the waves have a strong geomorphological effect on the abandoned estuary but are relatively weak in the current estuary. These findings have important theoretical value for understanding the evolutionary mechanism of dynamic geomorphology in the YRD. [ABSTRACT FROM AUTHOR]