Next Article in Journal
Recent Advances in Organic Pollutant Removal Technologies for High-Salinity Wastewater
Previous Article in Journal
Methane Emissions from Wetlands on the Tibetan Plateau over the Past 40 Years
 
 
Search for Articles:
Title / Keyword
Author / Affiliation / Email
Journal
Article Type
 
 
Advanced Search
 
Section
Special Issue
Volume
Issue
Number
Page
 
Journals
Water
Volume 17
Issue 16
10.3390/w17162493
water-logo
Submit to this Journal Review for this Journal Propose a Special Issue
► Article Menu

Article Menu

share Share announcement Help format_quote Cite question_answer Discuss in SciProfiles
first_page
settings
Order Article Reprints
Font Type:
Arial Georgia Verdana
Font Size:
Aa Aa Aa
Line Spacing:
Column Width:
Background:
Article

The Influence of the Sediment and Water Transported by the Yellow River on the Subaqueous Delta Without Water and Sediment Regulation

by
Junyao Song
1,
Bowen Li
1,2,*,
Kaifei He
1 and
Xuerong Cui
1
1
College of Oceanography and Space Informatics, China University of Petroleum (East China), Qingdao 266580, China
2
Technology Innovation Center for Maritime Silk Road Marine Resources and Environment Networked Observation, Ministry of Natural Resources, Qingdao 266580, China
*
Author to whom correspondence should be addressed.
Water 2025, 17(16), 2493; https://doi.org/10.3390/w17162493
Submission received: 24 July 2025 / Revised: 16 August 2025 / Accepted: 20 August 2025 / Published: 21 August 2025
(This article belongs to the Section Water Erosion and Sediment Transport)
Browse Figures
Versions Notes

Abstract

Globally, sediment transport from rivers and the morphological evolution of deltas are strongly shaped by human activities. The Yellow River Delta is a typical representative of this. In this paper, Delft 3D v4.01.00 software was used to simulate the sediment diffusion in the subaqueous delta of the Yellow River in 2017 so as to explore the influence of the sediment and water transported by the Yellow River on the subaqueous delta without water and sediment regulation. The results reveal the occurrence of a low–high–low suspended sediment concentration distribution from the coastlines to the far shore. The main accumulation areas shifted from the coasts of Bohai Bay and Laizhou Bay in the dry season to the estuary in the wet season. The sediments entering the sea formed deposition zones along the coastline, and erosion zones were formed outside these deposition zones, with a maximum depth of about 5 m. In 2017, the impact of the sediment inflow into the Yellow River on its subaqueous delta generally resulted in the erosion being greater than the sedimentation, and the erosion/deposition volume in 2017 was −1.28 × 108 m3, and the estimated critical value of the sediment inflow balance was 2.13 × 108 tons.

1. Introduction

Rivers worldwide transport over 12 billion tons of sediment to the oceans each year, with Asian rivers contributing more than 70% of this total [1]. Fluvial and estuarine systems represent critical interfaces between terrestrial and marine environments, where complex dynamics govern sediment transport, geomorphological evolution, and ecosystem functioning. In fluvial dynamics, sediment movement is primarily driven by water discharge, flow velocity, and channel morphology, with processes such as erosion, entrainment, and deposition shaping riverbed evolution and floodplain development [2,3]. Estuarine dynamics, by contrast, involve intricate interactions between river runoff, tidal currents, wind-generated waves, and saltwater intrusion [4,5,6,7]. Sediments are not only direct carriers of the interaction between fluvial and marine processes but also drive the formation of unique landforms such as deltas [8], serving as a key link connecting terrestrial and marine material cycles and dynamic coupling between land and sea. The formation, evolution, and stability of deltas are precisely the products of the long-term interaction between sediments, fluvial hydrodynamics, and marine dynamics [9].
As one of the rivers with the largest sediment discharge in the world, the Yellow River is a typical epitome that demonstrates the role of sediments in the dynamic interactions between rivers and estuaries. Since the establishment of the People’s Republic of China in 1949, extensive research and exploration have been conducted on sediment deposition issues in the Yellow River [10]. In 2002, a significant milestone was achieved with the launch of the water and sediment regulation project. The water and sediment regulation project is an engineering measure that entails the coordinated operation of reservoirs including the Wanjiazhai Reservoir, Sanmenxia Reservoir, and Xiaolangdi Reservoir, to release water and sediment intensively during specific periods, thereby creating artificial flood peaks. After the implementation of the water and sediment regulation project, the sediment from the Loess Plateau in the middle reaches of the Yellow River was no longer stagnant due to river channel siltation, and it is now swiftly transported to the lower reaches through the regulated water flow, eventually being deposited in the estuarine delta.
In recent decades, over 30% of the annual total sediment discharge has been attributed to the water and sediment regulation [11], which have effectively reduced sediment deposition in the lower Yellow River channel while optimizing the allocation of water and sediment resources. However, due to the insufficient water inflow of the Yellow River in 2017, the reservoirs failed to coordinate to release artificial flood peaks and did not form high-sediment concentration flow that scours the downstream river channels [12]. Consequently, the water and sediment regulation was suspended that year. When hydrological conditions improved in 2018, the Yellow River Conservancy Commission resumed the water and sediment regulation. The suspension of water and sediment regulation for one year is destined to impact the state of the subaqueous delta of the Yellow River. Therefore, it is essential to study how influxes from the Yellow River impacted erosion/deposition in 2017, which is of great value for revealing the influencing mechanism of water and sediment changes in the Yellow River on the estuary’s geomorphology [13], optimizing water and sediment regulation strategies, maintaining estuarine ecological security, and promoting sustainable environmental development.
In the field of water and sediment research, scholars tend to focus on utilizing remote sensing inversion, remote sensing image processing, and other techniques to explore the spatiotemporal distribution of suspended sediment and the influences of driving factors on its concentration [14,15,16]. In recent years, numerical simulation has been widely applied in sediment dynamics research due to its numerous advantages such as scientific processes and visualization of results [17,18], and it has gradually become an essential method for studying water and sediment in rivers and estuaries [19,20]. Classical hydrodynamic models include the EOCMSED hydrodynamic sediment transport model, the EFDC Explorer 3D environmental fluid dynamics model, the Danish DHI MIKE hydraulic model, and the Dutch Delft 3D hydrodynamic model [21,22,23,24]. Although hydrodynamic numerical simulation has been widely used in the design of water conservancy projects, its application to the erosion and deposition of the Yellow River Delta is limited due to its focus on researching water and sediment movement processes. However, a comprehensive understanding of the current erosion and deposition status of the subaqueous delta requires numerical model simulation. Current studies on the Yellow River Estuary’s water and sediment using numerical simulation have mainly considered the influences of regulation. Nevertheless, assessing the impact of the sediment inflow on the subaqueous delta of the Yellow River without regulation is still important for implementing regulation programs.
Therefore, this study aims to build a model to analyze the suspended sediment concentration (here referring to simulated surface suspended sediment concentration) and the erosion/deposition depth of the subaqueous delta in 2017 (a year when water and sediment regulation was suspended in the Yellow River) and to evaluate the impact of the sediment influx from the Yellow River on the subaqueous delta under non-regulation conditions. This study can fully align with the Three Yellow Rivers system [25] and enrich experimental methods. The research results can not only provide numerical references for the Yellow River Water Conservancy Commission in implementation but also offer scientific support for coastal engineering disaster prevention near estuaries.

2. Materials and Methods

2.1. Study Area

Flowing through the Loess Plateau where the loose loess is highly prone to erosion, and with soil erosion aggravated by irrational land use, the Yellow River has become the river with the highest sediment content in the world. The huge sediment transport volume led to the formation of the extensive Yellow River Delta [26]. As shown in Figure 1, the Yellow River Delta is located in northeastern Shandong Province, China, spanning the southern coast of Bohai Bay and the western coast of Laizhou Bay. This delta, with a coastline of 227 km [27], consists of both terrestrial and subaqueous components [28]. The subaqueous delta deposit body formed in the estuary and the nearby sea area [29] forms a semi-ring around the land delta, and the outer edge extends to water depths of 10–22 m, covering both bay areas.
The study area has a temperate monsoon climate, with hot and rainy summers and cold and dry winters. The period from June to August is the wet season, while the period from December to February is the dry season. The annual average rainfall in the study area is approximately 609 mm, with 70% of it concentrated in the wet season [30]. In the sea area of the study region, severe waves are generated by the winds of the Bohai Sea, characterized by short periods and obvious seasonal and interannual variations. The tidal properties of the study area are complex; most of the sea area is characterized by an irregular semi-diurnal tide, and the tide-free area is characterized by a regular diurnal tide, which is solely produced by the mutual cancelation of the tidal waves and reflected tidal waves, and its position changes with the changes in the Yellow River, the delta coast morphology, and the submarine topography [31]. The subaqueous delta sediment is composed of sand, silt, and clay and has a high water content, high porosity, and low strength [32]. The nearshore sediment exhibits obvious zonation, and the general trend is that the clay content is lower near the shore and higher away from the shore [33].

2.2. Mathematical Model

The classic hydrodynamic models include the Delft 3D model, EOCMSED model, DHI MIKE model. Given the relatively shallow water depth and limited field measurement data in the study area, this study utilized the Delft3D model, which is well-suited for shallow water environments and offers high simulation accuracy while requiring relatively less input data [34]. The model used to conduct the simulation calculations in the Delft 3D software is a three-dimensional hierarchical σ-coordinate shallow water mathematical model, which is numerically solved using the alternating-direction implicit (ADI) method [35]. It can ensure fast and smooth calculation under the premise of conservation of mass, momentum, and energy. In addition, Delft 3D has seven modules, including the FLOW and WAVE modules. These modules can be mutually coupled to achieve hydrodynamic simulations under the influences of various dynamic factors. Delft 3D has been widely applied to the simulation of the processes and analysis of the mechanisms of hydrodynamics, sediment transport, and dynamic geomorphology in estuarine and coastal areas [17,36,37].
The wave module adopts SWAN model [38]. The SWAN model can accurately calculate and output the wave characteristic parameters of the study area, such as the wave height and wave period, with the help of input data such as topography and wind field data. It can be better applied to study areas such as shelf marginal seas and shallow estuaries. The SWAN model can be coupled with Delft 3D and exchange data on the set time step to improve the accuracy and efficiency of the simulation. It has been successfully applied to various wave numerical simulations [39,40,41].

2.3. Model Construction

In this study, the Delft 3D model was used to simulate the suspended sediment concentration, water depth, and erosion/deposition depth of the Yellow River subaqueous delta in 2017. The flow chart of model construction is shown in Figure 2.

2.3.1. Model Grid and Boundary Conditions

Since the water discharged by the Yellow River into the sea affects not only the estuary but also the surrounding area, in order to simulate these areas simultaneously, the Delft 3D model grid covered the estuary, Laizhou Bay, and Bohai Bay. The study area was selected using OpenEarthTools (https://sourceforge.net/projects/openearthtools, accessed on 28 September 2017), and the Grid module within the Delft 3D model was utilized to grid the simulation area (Figure 3). The rectangular grids used for simulations had a cell size of 1 km × 1 km, and the total number of grid cells was 392 × 182. The model adopted the σ-coordinate system in the vertical direction and was divided into 10 layers. The open boundary of the river was located at the current estuary, and the daily runoff data from the Lijin Hydrological Station of the Yellow River Conservancy Commission was used to determine appropriate river flux boundary conditions. The offshore open boundary was set along the boundary line connecting Longkou and Caofeidian. To allow the model to more accurately simulate the actual marine dynamic changes, the open boundary of the model used the tidal forcing data provided by the tidal prediction solution for the ocean version 8 (TPXO8) global tidal model. The harmonic constants of four major tidal components were selected to reflect the tidal dynamic characteristics of the study area. The coastline boundary data were based on satellite scanning images. The terrain data were based on the Earth topography 1 arc-minute global relief model (ETOPO1) global elevation dataset published by the National Geophysical Data Center. The spatial resolution of the dataset was 1 arc minute, which could provide the seabed topographic feature data for the Bohai Sea required for this study. The water depth data used in the study were obtained from OpenEarth. The nearshore water depth data were calibrated using bathymetric data provided by the Yellow River Conservancy Commission.

2.3.2. Model Parameter Settings

The SED (sediment transport) module in Delft 3D can be coupled with the FLOW module, and the input point of the water and sediment discharge data is added at the estuary position to input the relevant data. Several rivers flow into the Bohai Sea, but more than 90% of the terrestrial sediments originate from the Yellow River; therefore, this study only considered the water and sediment input from the Yellow River. The key parameters for this study were obtained from data from Lijin Station (its location is shown in Figure 1), the last observation station before the Yellow River flows into the sea (Table 1). The data for the water discharge and sediment discharge from the Yellow River into its estuary required for the simulation were obtained from the Yellow River Sediment Bulletin published by the Yellow River Water Conservancy Commission. The wind speed and direction data for the study area were provided by the National Meteorological Science Data Center. Additionally, based on a previous similar study [24], other necessary parameters for modeling were set as follows: gravitational acceleration = 9.81 m/s2; water density = 1025 kg/m3; horizontal turbulent viscosity coefficient of water = 0.4 m2/s; horizontal turbulent diffusion coefficient of water = 0.004 m2/s; air density = 1 kg/m3; bulk density of sediment = 1970 kg/m3; median grain size of sediment = 0.036 mm [42]; dry density of sediment = 1600 kg/m3 [43]. The bottom roughness was set as the Manning’s roughness [44], with n = 0.03.
The SWAN module and the FLOW module in Delft 3D matched the same water depth through the grid and used the wind field data as the SWAN driver file. The time step was set to 1 min, and the interaction time step was set to 0.5 h. Each data output interacted with the FLOW module of Delft 3D, which could ensure that the data output by the two modules matched. The model simulation period was 1 year, from 1 January to 31 December 2017.

3. Simulation Results

The simulation results of the model were verified using field observation data for the Yellow River subaqueous delta. The verification mainly included four aspects: the current velocity, tidal range, surface suspended sediment concentration, and the seabed morphology. The distribution of the observation sites where the research team collected the measured data for the Yellow River delta is shown in Figure 4.

3.1. Current Velocity Verification

The data collected by the research team at the Yellow River Estuary (119.02 E, 37.84 N) from 19 December 2016 to 11 January 2017 were utilized as validation data to verify the calculated current velocity results. The variations in the simulated and measured current velocity with time are shown in Figure 5. Both current velocities fluctuated within the range of 0 to 0.5 m/s. The fluctuation range of simulated current velocity was slightly larger than that of measured current velocity, which may have been caused by the deviation between the simulated and actual wind speeds. Given that Pearson’s r of the measured and simulated current velocity was 0.69 (Figure 6) and the RMSE was 0.07 m/s, which are basically consistent with previous results [17,45], it is considered that the simulation of the current velocity by the model was acceptable.

3.2. Tidal Range Verification

The validation of the tidal range simulation results was conducted using observation data from coastal stations along Laizhou Bay (119.16 E, 37.19 N) from August to September 2014. The variations in the simulated and measured tidal range with time are shown in Figure 7. Both trends were basically the same and fluctuated between −0.6 and 0.6 m. The Pearson’s r between the measured and simulated tidal ranges was 0.94 (Figure 8), and the RMSE was 0.09 m. These results are better than results of previous studies [45,46]. This indicates a general consistency between the simulated and measured tidal ranges, suggesting that the tidal simulation was reliable.

3.3. Suspended Sediment Concentration Verification

The actual suspended sediment concentration measurements on the surface layer collected by the research team on 15 December 2019 were used to validate the simulated suspended sediment concentration results. The result reveals that the simulated values and the observed values exhibited a good fit. There was a significant correlation between these two datasets (Pearson’s r = 0.87; Figure 9). However, differences due to variations in the wind speed, wave conditions, and other factors during the study period led to disparities between the measured and simulated suspended sediment concentrations under the combined influence of the marine dynamics.

3.4. Seabed Morphology Verification

The simulated seabed morphology data at the end of 2017 were verified using the measured seabed morphology data released by the National Marine Science Data Center. A total of 350 points were selected in the area ranging from the coast to the offshore of Laizhou Bay. As depicted in Figure 10, a strong correlation was observed between the simulated and measured seabed depth datasets (Pearson’s r = 0.89; RMSE = 1.56 m). The model discrepancies may have originated from interpolation errors in the remote sensing data inputs and the cumulative effects of daily minor inaccuracies during simulation processes. Since the model error was within the acceptable range, the model was suitable for this study.
Based on the validation results for the current velocity, tides, suspended sediment concentration, and seabed depth, it is evident that while there are minor discrepancies in the specific numerical changes in the simulated results of the Delft 3D model and the measured data, a significant correlation exists between the simulated and measured data. It is concluded that the model demonstrates a good simulation capability for sediment transport, and the simulation results can effectively capture the hydrodynamic variation process of the Yellow River subaqueous delta. Therefore, this model can be utilized for qualitative and approximate quantitative studies on erosion and deposition processes influenced by wind waves in the subaqueous delta.

4. Discussion

From a long-term perspective, meteorological parameters of the study area in 2017 fell within the normal fluctuation range of long-term averages. This indicates that the difference between 2017 and other years is mainly reflected in the changes in water and sediment discharge caused by the non-implementation of water and sediment regulation. This characteristic means that conventional influencing factors are equally applicable to the analysis of 2017, and the research results derived from the data of this year can reflect the objective laws under typical meteorological conditions in the region. Meanwhile, this study is conducted from an overall regional perspective and does not consider the specific impacts of human activities and short-term events on the erosion/sedimentation processes in local areas over a short time.

4.1. Suspended Sediment Concentration

To enable convenient description, the area where the suspended sediment concentration exceeded 100 g/m3 is defined as the high-value area. The suspended sediment concentration in the Yellow River subaqueous delta generally demonstrated a low–high–low distribution pattern from the coastlines to the offshore areas. Specifically, except for near the estuary areas, low concentrations were observed along the coast of both Bohai Bay and Laizhou Bay, while high concentrations occurred in shallow water areas near coastlines, and the values decreased further away from the shore.
The distribution of the suspended sediment concentration during the period from December to February, which is part of the dry season, was highly consistent. Therefore, this study selected one typical case for analysis. Taking 0:00 on January 16 as a representative date, the spatial distribution of the suspended sediment concentration during the dry season (Figure 11a) illustrated strip-like patterns of high-value areas along the coasts of Bohai Bay and Laizhou Bay, whereas there were no large-scale high-value areas in the regions near the estuary. Some studies have demonstrated that wind waves have a significant impact on the concentration of suspended sediment [7,45]. Due to the shallow water depth in the study area, the effect of wind was particularly significant in the dry season. Strong wind-driven waves caused erosion and resuspension of seabed sediments in the nearshore areas of the two bays [47]. During the dry season, the prevailing wind direction in the study area was northerly, so most of the suspended sediments stirred up were distributed along the nearshore and rarely transported to the offshore. Additionally, due to the weakened runoff in the dry season and the wave-dissipating effect of the estuarine topography [48], the concentration of suspended sediments in the area near the estuary was lower than that in the nearshore of the two bays.
Similarly, the distribution of the suspended sediment concentration from June to August, which was within the wet season, also exhibited a high degree of similarity. Taking 0:00 on July 30 as a representative time, the spatial distribution of the suspended sediment concentration in the Yellow River subaqueous delta during the wet season is illustrated in Figure 11b. During this period, new characteristics of the suspended sediment concentration within the delta were observed. The high-concentration areas were primarily concentrated in specific coastal estuaries, and the Yellow River Estuary was the main accumulation area for suspended sediments. Conversely, there were no distinct high-concentration areas in the sea regions of Bohai Bay and Laizhou Bay. This shift can be attributed to variations in the sediment load input by the Yellow River. During this period, the amount of sediment entering the sea reached its maximum, and a huge quantity of sediments were rapidly deposited and accumulated around the estuary [49]. In addition, previous studies have suggested that the diffusion and transport of sediments are jointly influenced by runoff and marine dynamics [4,5,6]. Since there were no water and sediment regulation measures in 2017, the runoff and sediment discharge of the Yellow River were lower than those in previous years. The areas near the estuary were affected by the mutual offset between the runoff and marine dynamics, so the tides failed to transport all of the sediments away [50,51], and the suspended sediments failed to spread outward without the driving force of stronger runoff.
Representative points (Figure 12) were selected in the vicinity of the estuary (Point A), Bohai Bay (Point B), and Laizhou Bay (Point C) to observe the changes in the simulated suspended sediment concentration in the study area in 2017 (Figure 13). It was found that during the winter dry season, the suspended sediment concentration near estuary areas was generally low, while in the summer wet season, the levels were higher, reaching a peak value of around 500 g/m3. In contrast, Bohai Bay and Laizhou Bay experienced the highest levels of suspended sediments during the winter dry season, with almost negligible amounts present during other periods. The peak values in Bohai Bay exceeded those in Laizhou Bay. More importantly, the value in Bohai Bay exceeded 800 g/m3 compared to the value of ~450 g/m3 in Laizhou Bay. The main reason for this phenomenon is that Bohai Bay is more prone to disastrous weather such as cold waves in the dry season, accompanied by northerly winds of force 7–8 [52], and the maximum wave height could exceed 6 m, which leads to intense sediment lifting. The combined effect of tidal current and wind results in a greater bed shear stress, making the resuspension of sediment more intense [53]. This causes the maximum suspended sediment concentration in some areas to be extremely high. The temporal variations in the suspended sediment concentrations at representative points aligned with the seasonal characteristics driven by the river runoff and wind waves throughout the wet and dry seasons.

4.2. Water Depth and Erosion/Deposition Depth

The water depth distribution map of the Yellow River subaqueous delta is shown in Figure 14. Spatially, the study area exhibited a deep–shallow–deep pattern from the coastlines to the offshore areas, with deeper water closer to the coastline, shallower water in the nearshore areas, and increasing depth with increasing distance from the coast. Comparison of the water depth distributions at the end of the dry and wet seasons revealed that during the dry season (December to February), the water along the coastline of Bohai Bay became shallower, while the nearshore shallow areas became deeper. On the west side of Laizhou Bay, the depth increased nearer to the shore and decreased with increasing distance offshore, and the changes in the estuary were less pronounced. In contrast, during the wet season (June to August), significant shallowing occurred in the estuary and on the west side of Laizhou Bay, while the shallow nearshore waters deepened. Minimal changes were observed in Bohai Bay.
Combined with the analysis of the erosion/deposition depth distribution (Figure 15), it is evident that the sediments discharged by the Yellow River into the sea accumulated along the coastlines, forming deposition zones. This phenomenon is primarily influenced by seabed topography. Previous studies have indicated that seabed topography influences the transport of sediments by altering the direction and intensity of hydrodynamic movements [54,55]. When sediment-laden bottom currents encounter significant bathymetric variations, the transport of sediments from deeper to shallower zones becomes inhibited, resulting in localized deposition [56]. Due to the effects of runoff and tides, the deposition zones widened northward and southward along the coastlines, extending from the estuary. The erosion zones formed outside the deposition zones due to sediment supply deficiency caused by topographic interception, coupled with enhanced wave and tidal current activity, and wider erosion zones were observed on the eastern coasts of Bohai Bay and the western coasts of Laizhou Bay.
During the dry season (December to February), apart from the deposition zones, there was also evidence of deposition from northern sea areas of the estuary to the west side of Laizhou Bay on the outside of the erosion zones. It has been observed that the main reason for this phenomenon is that the residual current [57] is relatively strong in the dry season. The residual current near the estuary coast moves southward [58], while the residual current near the coast in the northwestern part of Laizhou Bay moves toward the open sea. The convergence of these two currents accelerates the transport and deposition of sediment. In contrast, during the wet season (June to August), the width of the erosion zones increased between the eastern sea areas of the estuary and the west side of Laizhou Bay, and the deposition previously observed along the outer edge of the erosion zone was no longer significant. Due to the weak monsoon in the study area during the wet season, under the control of runoff and residual currents, sediment is mainly transported southward [49]. Meanwhile, hindered by topography and waves, the sediments are not carried further offshore and instead accumulate more along the coast. Therefore, the deposition zone between the southern sea areas of the estuary and the west side of Laizhou Bay significantly widened, with notably higher deposition intensity compared to other areas (Figure 15b). Similarly, influenced by factors such as currents, the deposition intensity in the southern sea areas of the estuary exceeded that in the northern sea areas.
The erosion/sedimentation depth along the normal direction of the coastline in the study area was observed. It was determined that the maximum erosion depth in the erosion zone was approximately 5 m, and most of the erosion occurred in the sea area with water depths of less than 10 m. The maximum deposition thickness exceeded 10 m in the Bohai Bay and the estuary, while it reached over 8 m in the Laizhou Bay. The areas with the greatest deposition thicknesses were located in the sea regions within 10 km of the shore. The area most affected by sedimentation extended from the eastern sea areas of the estuary to the west side of Laizhou Bay, and the influence range covered up to 11.4 km outside the estuary.

4.3. Relationship Between the Erosion/Deposition of the Yellow River Subaqueous Delta and the Sediment Flux into the Sea

The deposition volume of each grid was calculated by multiplying its erosion/deposition depth at a given time by the corresponding area. Summing up these volumes provided the total deposition volume for that particular time period within the study area. Using this method, the total deposition volume for the study area over 12 months in 2017 was calculated (Table 2). Since the Yellow River subaqueous delta includes the estuary area and the areas of two bays, and the amount of sediment in the offshore area is so small that it can be ignored, the calculated deposition volume in the study area may reasonably approximate the total sediment volume of the entire Yellow River subaqueous delta. The calculation results indicate that six of the months exhibited erosion trends, and the remaining six months exhibited deposition trends. The maximum erosion occurred in March, with an estimated value of 1.4915 billion cubic meters, whereas the maximum deposition occurred in February, reaching approximately 923.9 million cubic meters. The overall amount of erosion/deposition during 2017 was calculated to be –128.4 million cubic meters, indicating an overall trend of erosion within the study area during 2017.
Comparison of the variations in the monthly water discharge, sediment discharge, and total deposition volume (Figure 16) revealed that from March to August, the primary factor influencing the erosion/deposition of the Yellow River subaqueous delta was the sediment flux into the sea. During this period, increases in both the water discharge and sediment discharge led to an increase in the deposition volume within the subaqueous delta. Conversely, a decrease in either the water discharge or sediment discharge resulted in a reduction in the deposition volume. In contrast, from December to February, wind and waves became dominant factors affecting the erosion of the Yellow River subaqueous delta. The water discharge had a limited impact on the sediments near the Yellow River estuary, with weak correlations between the erosion of the subaqueous delta and the water discharge and sediment discharge.
The mass is equal to the density multiplied by the volume. The total erosion volume calculated in the previous section is 128.4 million m3. By multiplying this volume by the average sediment density (1600 kg/m3), it is calculated that the mass required to fill the gap is 205.392 million tons. When added to the Yellow River’s 2017 sediment discharge into the sea (7.720 million tons), it is revealed that an estimated total sea entry sediment mass of 213.112 million tons is required to maintain balance within the study area. Previous studies based on extensive measured data and satellite remote sensing data have examined the relationships between changes in the area of the terrestrial and submarine deltas of the Yellow River with the amount of sediment entering the sea [9,59,60]. They estimated that the annual average critical value for maintaining balance between erosion and deposition within the delta ranges from 50 to 331 million tons. Before the implementation of the water and sediment regulation project (before 2002), the critical value was 331 million tons [59], while the value in this study is lower than this level. This indicates that the annual water and sediment regulation has played a positive role in the sedimentation process of the Yellow River subaqueous delta, effectively reducing the sediment flux required to maintain the balance of the delta. In the period from 2002 to 2016, when the water and sediment regulation project was implemented normally, a previous study estimated the critical value to be 130 million tons [61], and the value in this study is significantly higher than this level. This suggests that the suspension of the water and sediment regulation project may have had a significant impact on the Yellow River subaqueous delta. Once the project was suspended, the erosion–sedimentation balance of the subaqueous delta was disturbed. In fact, the evolution of the Yellow River Delta has the characteristics of erosion here and deposition there [62]. It should be noted that this balance only corresponds to our entire study area, and different parts may exhibit distinct behaviors.
It takes 213.112 million tons of sediments to reach the critical value for attaining a balance between erosion and deposition in the study area; however, in fact, the sediments discharged into the sea in 2017 were far below this required value. The insufficient supply of sediments into the sea caused the subaqueous delta of the Yellow River to erode, indicating that water and sediment regulation has a significant impact on the evolution of estuaries and delta geomorphology.

5. Conclusions

In this study, the erosion and deposition conditions of the Yellow River subaqueous delta were simulated using the Delft 3D software. The simulation model results were validated against measured data, providing the characteristic distributions of the water depth, suspended sediment concentration, and erosion/deposition depth within the sea area of the subaqueous delta. In addition, the influences of sediment discharge into the sea on the erosion and deposition processes of the subaqueous delta were analyzed. The main conclusions of this study are summarized below.
(1)
The suspended sediment concentration in the Yellow River subaqueous delta generally exhibited a low–high–low distribution pattern from the coastlines to the areas far from shore. During the dry season, the high-concentration areas were strip-shaped and located near the coasts of Bohai Bay and Laizhou Bay, with values exceeding 800 g/m3. In the wet season, the estuary became the main aggregation area, with a peak concentration of around 500 g/m3, and there were no obvious high-concentration areas in either bay.
(2)
Sediments transported by the Yellow River deposit along the coastline, forming deposition zones with a maximum thickness greater than 10 m. The area in which the influence of sedimentation was the greatest extended from the eastern sea areas of the estuary to the west side of Laizhou Bay, and the influence range extended to 11.4 km outside the estuary. Outside these zones, erosion zones formed under the action of wind waves, with a maximum depth of around 5 m. Wider zones occurred on the east coast of Bohai Bay and the west coast of Laizhou Bay.
(3)
In 2017, the overall impact of the sediment flux from the Yellow River into its submarine delta exhibited the characteristic of erosion exceeding deposition, and the total annual erosion/deposition volume was estimated to be −128.4 million cubic meters. It is estimated that a total of approximately 213.1 million tons of sediments into the sea is required to maintain equilibrium between erosion and deposition. Water and sediment regulation has a significant impact on the evolution of the erosion and deposition landforms of the Yellow River subaqueous delta.
The interruption of the water and sediment regulation measures in 2017 had an impact on the sedimentary environment of the estuaries and subaqueous deltas, indicating that at this stage, reservoir regulation is still an important means of alleviating the negative effects of river dam construction and maintaining the stability of estuaries and deltas. The results identify the key areas of erosion and deposition in the Yellow River subaqueous delta as well as the status of sediment supply and demand, providing a basis for targeted implementation of ecological restoration and engineering protection work. Meanwhile, this study reveals the significant impact of water and sediment regulation on geomorphology and recommends further optimizing the rhythm of water and sediment regulation to prevent ecosystem degradation. However, simple measures such as discharging sediment from reservoirs and scouring river channels are not a permanent solution that can solve the problem once and for all [63]. In the future, to better maintain the geomorphic stability and sustainable development of the delta, the scientific research and optimal management of the water and sediment regulation project should be further deepened. The water and sediment control scheme should be combined with other delta protection engineering measures, such as the Dutch delta protection project [64], wetland and vegetation restoration, and other overall planning, and appropriate reference should be made.
Furthermore, given the limitations of this study in terms of long-term trend analysis and model setup, the next phase of research will conduct simulation work for the year 2019 (a normal year for water and sediment regulation). This initiative aims to further improve the evaluation system for the impact of water and sediment regulation on erosion and deposition in the Yellow River subaqueous delta. Meanwhile, it will also carry out in-depth optimization of the model setup, including more refined evaluation and adjustment of parameters such as median particle size, so as to enhance the accuracy and reliability of the research conclusions.

Author Contributions

Formal analysis, J.S.; data curation, K.H.; writing—original draft preparation, J.S.; writing—review and editing, B.L.; supervision, X.C.; funding acquisition, B.L. All authors have read and agreed to the published version of the manuscript.

Funding

This research was funded by the “National Natural Science Foundation of China” (42107157); the “Fundamental Research Funds for the Central Universities” (24CX02031A); and the “annual sediment movement characteristics of the seabed boundary layer in Chengdao Oilfield” supported by Shandong Continental Shelf Marine Technology Co. Ltd. (HX20230616).

Data Availability Statement

The data presented in this study are available on request from the corresponding author. The data are not publicly available due to privacy.

Acknowledgments

Special thanks go to Jin Liao for helping with the completion of the in situ observations and this study.

Conflicts of Interest

The authors declare no conflicts of interest. The authors declare that this study received funding from Shandong Continental Shelf Marine Technology Co., Ltd. The funder was not involved in the study design, collection, analysis, interpretation of data, the writing of this article or the decision to submit it for publication.

References

  1. Syvitski, J.; Vörösmarty, C.; Kettner, A.; Green, P. Impact of humans on the flux of terrestrial sediment to the global coastal ocean. Science 2005, 308, 376–380. [Google Scholar] [CrossRef] [PubMed]
  2. Luzi, D.; Hassan, M.; Papangelakis, E.; Eaton, B. Cycles of aggradation and degradation in gravel-bed rivers mediated by sediment storage and morphologic evolution. Geomorphology 2021, 395, 108001. [Google Scholar] [CrossRef]
  3. Pryor, B.; Lisle, T.; Montoya, D.; Hilton, S. Transport and storage of bed material in a gravel-bed channel during episodes of aggradation and degradation: A field and flume study. Earth Surf. Process. Landf. 2021, 36, 2028–2041. [Google Scholar] [CrossRef]
  4. Burchard, H.; Schuttelaars, H.M.; Ralston, D.K. Sediment trapping in estuaries. Ann. Rev. Mar. Sci. 2018, 10, 371–395. [Google Scholar] [CrossRef] [PubMed]
  5. Zhang, X.; Fichot, C.G.; Baracco, C.; Guo, R.; Neugebauer, S.; Bengtsson, Z.; Ganju, N.; Fagherazzi, S. Determining the drivers of suspended sediment dynamics in tidal marsh-influenced estuaries using high-resolution ocean color remote sensing. Remote Sens. Environ. 2020, 240, 111682. [Google Scholar] [CrossRef]
  6. Van Der Wegen, M. Numerical modeling of the impact of sea level rise on tidal basin morphodynamics. J. Geophys. Res. Earth Surf. 2013, 118, 447–460. [Google Scholar] [CrossRef]
  7. Sun, H.; Xu, J.; Zhang, S.; Li, G.; Liu, S.; Qiao, L.; Yu, Y.; Liu, X. Field observations of seabed scour dynamics in front of a seawall during winter gales. Front. Mar. Sci. 2022, 9, 1080578. [Google Scholar] [CrossRef]
  8. Pan, Y.; Liu, S.; Xing, F.; Wang, Y.; Yu, Y.; Chen, T.; Liu, Q. Sediment gravity flows drive the buildup of the modern Huanghe (Yellow River) delta front. Mar. Geol. 2025, 480, 107468. [Google Scholar] [CrossRef]
  9. Han, X.; Chen, S.; Fu, Z.; Fan, Y.; Wang, P. Spatiotemporal evolution of erosion and deposition in the Yellow River submerged delta and its influencing factors. Mar. Sci. Bull. 2020, 39, 567–580. [Google Scholar]
  10. Wang, J. A primary framework on protection of ecological environment and realization of high-quality development for the Yellow River basin. Environ. Prot. 2020, 48, 18–21. [Google Scholar] [CrossRef]
  11. Li, Q.; Wang, A.; Wu, X.; Tu, D.; Wang, H. Water and sediment regulation of the Yellow River and its impact on hyperpycnal flow in the estuary. Mar. Geol. Front. 2021, 37, 52–63. [Google Scholar] [CrossRef]
  12. Wu, X.; Fan, Y.; Wang, H.; Bi, N.; Yang, Z.; Xu, C. Geomorphological responses of the lower river channel and delta to interruption of reservoir regulation in the Yellow River, 2015–2017. Chin. Sci. Bull. 2021, 66, 3059–3070. [Google Scholar] [CrossRef]
  13. Fan, Y.; Dou, S.; Yu, S.; Wang, G.; Wu, Y.; Xie, W. Research progress on hydrology-geomorphology-ecology system evolution and multidimensional regulation in Yellow River Delta. Adv. Water Sci. 2023, 34, 984–998. [Google Scholar] [CrossRef]
  14. Yang, C.; Li, Y.; Yang, J.; Shu, S. Remote sensing inversion and regularity analysis of suspended sediment in Pearl River estuary based on machine learning model. Bull. Surv. Mapp. 2023, 9, 117–123. [Google Scholar] [CrossRef]
  15. Yao, R.; Cai, L.; Liu, J.; Zhou, M. Gf-1 satellite observations of suspended sediment injection of yellow river estuary, china. Remote Sens. 2020, 12, 3126. [Google Scholar] [CrossRef]
  16. Yu, Z.; Zhang, J.; Chen, Z.; Hu, Y.; Shum, C.K.; Ma, C.; Song, Q.; Yuan, X.; Wang, B.; Zhou, B. Spatiotemporal evolutions of the suspended particulate matter in the Yellow River Estuary, Bohai Sea and characterized by Gaofen imagery. Remote Sens. 2023, 15, 4769. [Google Scholar] [CrossRef]
  17. Fan, Y.; Chen, S.; Pan, S.; Dou, S. Storm-induced hydrodynamic changes and seabed erosion in the littoral area of Yellow River Delta: A model-guided mechanism study. Cont. Shelf Res. 2020, 205, 10417. [Google Scholar] [CrossRef]
  18. Du, Y.; Li, W.; Shen, W.; Li, H. Research on improving the accuracy of suspended sediment numerical simulation by using remote sensing inversion data. J. Waterw. Harb. 2021, 42, 582–587. [Google Scholar]
  19. Li, Q.; Wang, Y.; Bai, T. Review on water and sediment regulation of the Yellow River. J. Northwest AF Univ. (Nat. Sci. Ed.) 2014, 12, 227–234. [Google Scholar] [CrossRef]
  20. Li, S.; Tian, J.; Zhan, S.; Wang, C.; Ren, Y.; Wang, T. Advances in research and application on three-dimensional numerical simulation of sediment transport in coastal waters. J. Ludong Univ. (Nat. Sci. Ed.) 2023, 39, 322–327. [Google Scholar] [CrossRef]
  21. Wang, X.; Han, S.; Wang, X. Application of ECOMSED model in sedimentation of Bohai Bay. Trans. Oceanol. Limnol. 2018, 6, 9–16. [Google Scholar] [CrossRef]
  22. Zăinescu, F.; Vespremeanu-Stroe, A.; Anthony, E.; Tătui, F.; Preoteasa, L.; Mateescu, R. Flood deposition and storm removal of sediments in front of a deltaic wave-influenced river mouth. Mar. Geol. 2019, 417, 106015. [Google Scholar] [CrossRef]
  23. Huang, L.; Chen, S.; Li, P.; Yang, M.; Liu, Q. Spatiotemporal distribution of suspended sediment in the tail channel of the Huanghe River Delta from 2016 to 2020. Mar. Sci. Bull. 2023, 42, 303–313. [Google Scholar]
  24. Li, B.; Liu, J.P.; Jia, Y. Comparison of the causes of erosion–deposition between Yellow River, Yangtze River, and Mekong River subaqueous delta l: Model building. Water 2022, 14, 3028. [Google Scholar] [CrossRef]
  25. Li, W.; Kou, H. Thoughts on the construction of digital twin Yellow River in the new stage. China Flood Drought Manag. 2022, 32, 27–31. [Google Scholar] [CrossRef]
  26. Shi, C. Sediment accumulation and dispersal in the Yellow River mouth since 1976. Yellow River 2020, 42, 41–45. [Google Scholar] [CrossRef]
  27. Zheng, S.; Han, S.; Tan, G.; Xia, J.; Wu, B.; Wang, K.; Edmonds, D.A. Morphological adjustment of the Qingshuigou channel on the Yellow River Delta and factors controlling its avulsion. Catena 2018, 166, 44–55. [Google Scholar] [CrossRef]
  28. Liu, J.; Kong, X.; Saito, Y.; Liu, J.P.; Yang, Z.; Wen, C. Subaqueous deltaic formation of the Old Yellow River (AD 1128-1855) on the western South Yellow Sea. Mar. Geol. 2013, 344, 9–33. [Google Scholar] [CrossRef]
  29. Jiang, C.; Pan, S.; Chen, S. Recent morphological changes of the Yellow River (Huanghe) submerged delta: Causes and environmental implications. Geomorphology 2017, 293, 93–107. [Google Scholar] [CrossRef]
  30. Li, X. Effect and Mechanism of Stimulated Precipitation Change on Soil Respiration in Yellow River Delta Wetland. Ph.D. Thesis, University of Chinese Academy of Sciences (Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences), Yantai, China, 2023. [Google Scholar] [CrossRef]
  31. Pelling, H.E.; Uehara, K.; Green, J.A.M. The impact of rapid coastline changes and sea level rise on the tides in the Bohai Sea, China. J. Geophys. Res. Ocean. 2013, 118, 3462–3472. [Google Scholar] [CrossRef]
  32. Zeng, L.; Zhan, C.; Wang, Q.; Liu, X.; Wang, L.; Li, X.; Wang, X.; Yu, X.; Zhang, J.; Cui, B. Sediment coarsening in tidal flats and stable coastline of the abandoned southern Yellow River sub-delta in response to fluvial sediment flux decrease during the past decades. Front. Mar. Sci. 2021, 8, 761368. [Google Scholar] [CrossRef]
  33. Yuan, P.; Bi, N.; Wu, X.; Zhang, Y.; Wang, H. Surface sediments at the subaqueous Yellow River delta: Classification and distribution. Mar. Geol. Quat. Geol. 2016, 36, 49–57. [Google Scholar] [CrossRef]
  34. Fan, Y.; Zhang, S.; Du, X.; Wang, G.; Yu, S.; Dou, S.; Chen, S.; Ji, H.; Li, P.; Liu, F. The effects of flow pulses on river plumes in the Yellow River Estuary, in spring. J. Hydroinform. 2023, 25, 36–50. [Google Scholar] [CrossRef]
  35. Li, M.; Sun, Z.; Gong, Y.; Hu, Y. Numerical simulation of sand-mud coexisting beach based on Delft-3D. Bull. Sci. Technol. 2019, 35, 109–113. [Google Scholar] [CrossRef]
  36. Luan, H.; Ding, P.; Wang, Z.; Ge, J. Process-based morphodynamic modeling of the Yangtze Estuary at a decadal timescale: Controls on estuarine evolution and future trends. Geomorphology 2017, 290, 347–364. [Google Scholar] [CrossRef]
  37. Cheng, X.; Zhu, J.; Chen, S. Extensions of the river plume under various Yellow River courses into the Bohai Sea at different times. Estuar. Coast. Shelf Sci. 2021, 249, 107092. [Google Scholar] [CrossRef]
  38. Xu, Z.; Dong, X.; Yin, Y. Numerical simulation of waves and wave-induced currents in the vicinity of a detached breakwater based on Delft 3D. J. Waterw. Harb. 2016, 37, 27–34. [Google Scholar]
  39. George, D.; Largier, J.; Pasternack, G.; Barnard, P.; Storlazzi, C.; Erikson, L. Modeling sediment bypassing around idealized rocky headlands. J. Mar. Sci. Eng. 2019, 7, 40. [Google Scholar] [CrossRef]
  40. Hoque, M.; Perrie, W.; Solomon, S. Application of SWAN model for storm generated wave simulation in the Canadian Beaufort Sea. J. Ocean. Eng. Sci. 2020, 5, 19–34. [Google Scholar] [CrossRef]
  41. Wang, N.; Chen, Q.; Zhu, L.; Sun, H. Integration of data-driven and physics-based modeling of wind waves in a shallow estuary. Ocean. Model. 2022, 172, 101978. [Google Scholar] [CrossRef]
  42. Li, B.; Jia, Y.; Zhang, Y.; Shan, H. Study on processes of seabed in the Yellow River Delta. J. Sediment Res. 2020, 45, 16–22. [Google Scholar] [CrossRef]
  43. Bi, N.; Shi, Y.; Ge, C.; Ba, Q.; Wu, X.; Wang, H. Impacts of morphological evoltion of the Huanghe River mouth by artificial regulation on deltaic sedimentation. Mar. Geol. Quat. Geol. 2024, 44, 1–14. [Google Scholar] [CrossRef]
  44. Park, S.S.; Lee, Y.S. A multiconstituent moving segment model for water quality predictions in steep and shallow streams. Ecol. Modell. 1996, 89, 121–131. [Google Scholar] [CrossRef]
  45. Ji, H.; Pan, S.; Chen, S. Impact of river discharge on hydrodynamics and sedimentary processes at Yellow River Delta. Mar. Geol. 2020, 425, 106210. [Google Scholar] [CrossRef]
  46. Wang, K.; Sun, Y.; Song, Y.; Xu, C.; Dong, L. Characteristics of shear fronts and dispersal of diluted water during the water-sediment regulation scheme in Yellow RiverDelta. Adv. Mar. Sci. 2019, 37, 551–564. [Google Scholar]
  47. Cai, X. Retrieve of spatial and temporal distribution of suspended sediment in Bohai Bay based on GF-1 remote sensing satellite. J. Atmos. Environ. Opt. 2020, 15, 134–142. [Google Scholar]
  48. Ding, D.; Li, S.; Ren, Y.; Zhou, Y. Sedimentary Characteristics of Storm—Surges in the Yellow River Delta and Adjacent Areas. Mar. Geol. Lett. 1994, 11, 1–3. [Google Scholar] [CrossRef]
  49. Qiao, S.; Shi, X.; Zhu, A.; Liu, Y.; Bi, N.; Fang, X.; Yang, G. Distribution and transport of suspended sediments off the Yellow River (Huanghe) mouth and the nearby Bohai Sea. Estuar. Coast. Shelf Sci. 2010, 86, 337–344. [Google Scholar] [CrossRef]
  50. Chu, Y.; Wu, W.; Li, P.; Chen, S. Temporal and spatial dynamics of suspended sediment and its driving mechanism in the Yellow River Estuary. Haiyang Xuebao 2022, 44, 150–163. [Google Scholar]
  51. Wu, W.; Fu, H. Spatial-temporal distributionof suspended sediment in the Yellow River Estuary based on GF-1 remote sensing satellite. In Proceedings of the 2021 (9th) China Water Conservancy Information Technology Forum, Jinan, China, 27 May 2021. [Google Scholar] [CrossRef]
  52. Cao, Y.; Liu, T.; Wang, H.; Yang, Z.; Liu, L. Winter 2017 marine weather review. J. Mar. Meteorol. 2018, 38, 76–86. [Google Scholar] [CrossRef]
  53. Xie, W.; Wang, X.; Guo, L.; He, Q.; Dou, S.; Yu, X. Impacts of a storm on the erosion process of a tidal wetland in the Yellow River Delta. Catena 2021, 205, 105461. [Google Scholar] [CrossRef]
  54. Zhang, G.; Liu, Z.; Luo, X.; Lu, C. Response of nearshore tidal characteristics to terrain complexity: Taking the south Yellow Sea and the northern waters of the East China Sea as examples. J. China Hydrol. 2023, 43, 84–88. [Google Scholar]
  55. Wu, W.; Li, Y. Study on the inter-annual distribution law of suspended sediment in the Yellow River estuary based on Landsat. Water Resour. Dev. Manag. 2022, 8, 1–6. [Google Scholar] [CrossRef]
  56. Li, B.; Jia, Y.; Liu, J.P.; Liu, X.; Wang, Z. Effect of wave, current and lutoclines on sediment resuspension in the Yellow River delta-front. Water 2020, 12, 845. [Google Scholar] [CrossRef]
  57. Wu, X.; Xu, J.; Wu, H.; Bi, N.; Bian, C.; Li, P.; Wang, A.; Duan, H.; Wang, H. Synoptic variations of residual currents in the Huanghe (Yellow River)-derived distal mud patch off the Shandong Peninsula: Implications for long-term sediment transport. Mar. Geol. 2019, 417, 106014. [Google Scholar] [CrossRef]
  58. Yang, Y.; Chen, S.; Xu, C. Morphodynamics and tidal flow asymmetry of the Huanghe River Estuary. Haiyang Xuebao 2021, 43, 13–25. [Google Scholar]
  59. Cui, B.; Li, X. Coastline change of the Yellow River estuary and its response to the sediment and runoff (1976–2005). Geomorphology 2011, 127, 32–40. [Google Scholar] [CrossRef]
  60. Bi, N.; Wang, H.; Yang, Z. Recent changes in the erosion-accretion patterns of the active Huanghe (Yellow River) delta lobe caused by human activities. Cont. Shelf Res. 2014, 90, 70–78. [Google Scholar] [CrossRef]
  61. Chen, S.; Gu, S.; Ji, H.; Xu, C. Processes of the Yellow River Mouth on new water and sediment condition. J. Sediment Res. 2019, 44, 61–67. [Google Scholar] [CrossRef]
  62. Zhao, G. Study on the longshore sediment transport and coastal erosion situation in the Modern Yellow River Delta area. Coast. Engin. 2006, 25, 29–38. [Google Scholar]
  63. Wu, X.; Bi, N.; Syvitski, J.; Saito, Y.; Xu, J.; Nittrouer, J.; Bianchi, T.; Yang, Z.; Wang, H. Can reservoir regulation along the Yellowver be a sustainable way to save a sinking delta? Earth Future 2020, 8, e2020EF001587. [Google Scholar] [CrossRef]
  64. Zegwaard, A.; Zwarteveen, M.; van Halsema, G.; Petersen, A. Sameness and difference in delta planning. Environ. Sci. Policy 2019, 94, 237–244. [Google Scholar] [CrossRef]
Water 17 02493 g001
Figure 1. Location of the Yellow River Delta.
Figure 1. Location of the Yellow River Delta.
Water 17 02493 g001
Water 17 02493 g002
Figure 2. The flow chart of model construction.
Figure 2. The flow chart of model construction.
Water 17 02493 g002
Water 17 02493 g003
Figure 3. Grid base map of the study area.
Figure 3. Grid base map of the study area.
Water 17 02493 g003
Water 17 02493 g004
Figure 4. Distribution of observation sites. ▲ indicates the tidal observation site; ■ indicates the current observation site; ● indicates the suspended sediment concentration observation site; and ★ indicates the seabed morphology.
Figure 4. Distribution of observation sites. ▲ indicates the tidal observation site; ■ indicates the current observation site; ● indicates the suspended sediment concentration observation site; and ★ indicates the seabed morphology.
Water 17 02493 g004
Water 17 02493 g005
Figure 5. Changes in measured current velocity and simulated current velocity.
Figure 5. Changes in measured current velocity and simulated current velocity.
Water 17 02493 g005
Water 17 02493 g006
Figure 6. Correlation between the simulated and measured current velocities (Pearson’s r = 0.69; RMSE = 0.07).
Figure 6. Correlation between the simulated and measured current velocities (Pearson’s r = 0.69; RMSE = 0.07).
Water 17 02493 g006
Water 17 02493 g007
Figure 7. Changes in the measured tidal range and simulated tidal range.
Figure 7. Changes in the measured tidal range and simulated tidal range.
Water 17 02493 g007
Water 17 02493 g008
Figure 8. Correlation between the simulated and measured tidal ranges (Pearson’s r = 0.94; RMSE = 0.09).
Figure 8. Correlation between the simulated and measured tidal ranges (Pearson’s r = 0.94; RMSE = 0.09).
Water 17 02493 g008
Water 17 02493 g009
Figure 9. Correlation between the measured and simulated suspended sediment concentrations (Pearson’s r = 0.87; RMSE = 0.02).
Figure 9. Correlation between the measured and simulated suspended sediment concentrations (Pearson’s r = 0.87; RMSE = 0.02).
Water 17 02493 g009
Water 17 02493 g010
Figure 10. Correlation between the measured and simulated seabed depths (Pearson’s r = 0.89; RMSE = 1.56).
Figure 10. Correlation between the measured and simulated seabed depths (Pearson’s r = 0.89; RMSE = 1.56).
Water 17 02493 g010
Water 17 02493 g011
Figure 11. Spatial distribution of the suspended sediment during the (a) dry season and (b) wet season in 2017 (the dry season is from December to February, and the wet season is from June to August).
Figure 11. Spatial distribution of the suspended sediment during the (a) dry season and (b) wet season in 2017 (the dry season is from December to February, and the wet season is from June to August).
Water 17 02493 g011
Water 17 02493 g012
Figure 12. Location of the representative points. Point A is the point representing the estuary, Point B is the point representing Bohai Bay, and Point C is the point representing Laizhou Bay.
Figure 12. Location of the representative points. Point A is the point representing the estuary, Point B is the point representing Bohai Bay, and Point C is the point representing Laizhou Bay.
Water 17 02493 g012
Water 17 02493 g013
Figure 13. Changes in the suspended sediment concentration at the representative points in the (a) estuary, (b) Bohai Bay, and (c) Laizhou Bay.
Figure 13. Changes in the suspended sediment concentration at the representative points in the (a) estuary, (b) Bohai Bay, and (c) Laizhou Bay.
Water 17 02493 g013
Water 17 02493 g014
Figure 14. Water depth distribution of the Yellow River subaqueous delta in the (a) initial state, (b) dry season, and (c) wet season in 2017.
Figure 14. Water depth distribution of the Yellow River subaqueous delta in the (a) initial state, (b) dry season, and (c) wet season in 2017.
Water 17 02493 g014
Water 17 02493 g015
Figure 15. The erosion/deposition distribution of the Yellow River subaqueous delta in the (a) dry season and (b) wet season in 2017.
Figure 15. The erosion/deposition distribution of the Yellow River subaqueous delta in the (a) dry season and (b) wet season in 2017.
Water 17 02493 g015
Water 17 02493 g016
Figure 16. Changes in the water discharge, sediment discharge, and deposition volume.
Figure 16. Changes in the water discharge, sediment discharge, and deposition volume.
Water 17 02493 g016
Table 1. Wind speed, wind direction, water discharge, and sediment discharge in the study area for each month of 2017.
Table 1. Wind speed, wind direction, water discharge, and sediment discharge in the study area for each month of 2017.
Month *Wind Speed
(m/s)		Wind Direction
(Deg)		Water Discharge
(108 m3)		Sediment Discharge (104 t)
January5.13153.2418.84
February5.2452.63710.2
March5.41803.26815.3
April6.51809.901160
May6.218010.2394.3
June6157.58.83951.3
July5.11808.19650.4
August4.6112.58.75873.9
September4.81804.48416.8
October5.322.57.5849.6
November5.7337.510.5596.4
December527011.84145
Note: * June to August is the wet season; December to February is the dry season.
Table 2. The monthly deposition volume in the Yellow River subaqueous delta in 2017.
Table 2. The monthly deposition volume in the Yellow River subaqueous delta in 2017.
MonthDeposition Volume (108 m3)
January−1.770
February9.239
March−14.915
April4.281
May0.562
June2.057
July−0.070
August−0.466
September−2.170
October2.090
November0.393
December−0.513
Disclaimer/Publisher’s Note: The statements, opinions and data contained in all publications are solely those of the individual author(s) and contributor(s) and not of MDPI and/or the editor(s). MDPI and/or the editor(s) disclaim responsibility for any injury to people or property resulting from any ideas, methods, instructions or products referred to in the content.

Share and Cite

MDPI and ACS Style

Song, J.; Li, B.; He, K.; Cui, X. The Influence of the Sediment and Water Transported by the Yellow River on the Subaqueous Delta Without Water and Sediment Regulation. Water 2025, 17, 2493. https://doi.org/10.3390/w17162493

AMA Style

Song J, Li B, He K, Cui X. The Influence of the Sediment and Water Transported by the Yellow River on the Subaqueous Delta Without Water and Sediment Regulation. Water. 2025; 17(16):2493. https://doi.org/10.3390/w17162493

Chicago/Turabian Style

Song, Junyao, Bowen Li, Kaifei He, and Xuerong Cui. 2025. "The Influence of the Sediment and Water Transported by the Yellow River on the Subaqueous Delta Without Water and Sediment Regulation" Water 17, no. 16: 2493. https://doi.org/10.3390/w17162493

APA Style

Song, J., Li, B., He, K., & Cui, X. (2025). The Influence of the Sediment and Water Transported by the Yellow River on the Subaqueous Delta Without Water and Sediment Regulation. Water, 17(16), 2493. https://doi.org/10.3390/w17162493

Note that from the first issue of 2016, this journal uses article numbers instead of page numbers. See further details here.

Article Metrics

Back to TopTop