the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
Application of Wave-current coupled Sediment Transport Models with Variable Grain Properties for Coastal Morphodynamics: A Case Study of the Changhua River, Hainan
Abstract. This study presents an integrated sand transport model that accounts for both wave and current actions, along with non-constant grain properties, to investigate sediment dynamics in the lower reaches of rivers. Taking the downstream and estuary of the Changhua River in Hainan Island as a case study, topographic data and sediment sampling were conducted in the field, complemented by remote sensing techniques. The model was rigorously validated using theoretical and empirical methods, demonstrating excellent agreement with observed suspended sediment concentrations at the Baoqiao Station. The findings indicate significant sediment deposition in the estuary and lower reaches of the Changhua River, influenced by a combination of hydrodynamic conditions and geological settings. Deposition in the estuary is primarily affected by the northeast-southwest coastal currents and wave action, while deposition in the river channel is associated with river constriction and variations in flow velocity. The models and methods developed in this study provide a scientific basis for sediment management and coastal evolution in similar downstream riverine environments and discuss the feasible scheme of sediment control in the downstream of Changhua River.
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Status: final response (author comments only)
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RC1: 'Comment on egusphere-2024-2154', Anonymous Referee #1, 02 Sep 2024
Comments can be found in the attached pdf documentÂ
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AC1: 'Reply on RC1', Yuxi Wu, 12 Sep 2024
The comment was uploaded in the form of a supplement: https://egusphere.copernicus.org/preprints/2024/egusphere-2024-2154/egusphere-2024-2154-AC1-supplement.pdf
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AC1: 'Reply on RC1', Yuxi Wu, 12 Sep 2024
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RC2: 'Comment on egusphere-2024-2154', Anonymous Referee #2, 20 Oct 2024
Review of the manuscript
‘Application of Wave-Current coupled Sediment Transport Models with Variable Grain
properties for Coastal Morphodynamics: A Case study of the Changhua River, Hainan’
by Wu et al. 2024
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In this study, the hydrodynamic and sediment transport modeling was carried out in the lower reaches of Changhua River in Hainan Island, and the influence of waves on the sediment dynamics of low sediment concentration rivers was discussed. The authors use a wave model containing Van Rijn formula to calculate bed load and suspended sediment transport, and consider various sediment properties of estuaries and main river channels. After the model calibration, the authors checked the erosion and deposition at several locations.
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The manuscript presents a study on the sediment transport in the Changhua River, with a focus on the integration of wave and current dynamics. While the research addresses an important topic in coastal geomorphology, several areas require refinement to enhance the clarity, accuracy, and overall impact of the research. Here are specific areas for improvement:
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Specific comments on the hydrodynamic model
- Do Txx, Txy, and Tyy in Equation (4) correspond to Tij in Line 140? If so, the corresponding terms should be explained in relation to the variable symbols.
- Line 202, what does this sentence mean? Is there an error in the expression? It is suggested to change "riverway" in Line 220 to "channel" to better match the scope of the study.
- There are errors in the use of symbols in Table 2. The mean grain diameter and median grain diameter have units, which are represented by φ, but the sorting coefficient is a unitless value. The same applies to Table 3.
- Line 241, the range expression for gravel (>2 mm), sand (2~0.063 mm), silt (0.063~0.004 mm) is problematic; the larger value should be placed after the smaller value. The legend of Figure 5 lacks units.
- The scope of the study in Figure 6 is not consistent with the description in Line 280; it is recommended to modify it. Additionally, according to the geographical location of the Changhua River, it is located in the southwest of Hainan Province, but it is described as the western part in Line 278? Line 287, how is the elevation measured by ADCP obtained? Can specific information about the survey vessel be provided to increase the credibility of the article's data?
- Line 314, remove the comma. "Model validation occurs from 10:00 on April 23, 2023, to 00:00 on April 30, 2023." has an extra comma.
- Section 3.3 lacks analysis of the hydrodynamic results, and the description of the hydrodynamic environment of the study area is insufficient. It is recommended to expand the text and analyze it in conjunction with the sediment transport model.
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Specific comments on the sand transport model
- Is the "Code for Design of River Regulation" mentioned in Line 370 some kind of authoritative provision? There are no citations of any literature on this regulation in the text. Is this method applicable to the lower reaches of the Changhua River?
- Line 408, only the first appearance of an abbreviation in the article needs to be spelled out in full; SSC can be expressed directly here.
- The simulation results of the sediment transport model only analyze the thickness changes of the sediment, without a detailed description of the specific movement of the sediment. The measures for sediment control mentioned in Section 4 do not propose a specific implementation plan. It is suggested to revise the content of Section 4, combine the simulation results of the sediment transport model with the hydrodynamic results, and analyze the movement of sediment driven by water flow.
Citation: https://doi.org/10.5194/egusphere-2024-2154-RC2 -
AC2: 'Reply on RC2', Yuxi Wu, 20 Oct 2024
The comment was uploaded in the form of a supplement: https://egusphere.copernicus.org/preprints/2024/egusphere-2024-2154/egusphere-2024-2154-AC2-supplement.pdf
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