Review Reports - Mike 21 Model Based Numerical Simulation of the Operation Optimization Scheme of Sedimentation Basin

Round 1

Reviewer 1 Report

The present paper “Mike 21 Model-based Numerical Simulation of the Operation Optimization Scheme of Sedimentation Basin” deals with the proposal of a simulation model of the sedimentation basin of a particular canal ws developed using Mike 21 software to
analyse its water and sediment characteristics and conditions in different periods. This is an interesting topic, but some comments are proposed by this reviewer.

Abstract. This section is adequate, with the main objectives of the work and main achievements. Nevertheless, in this reviewer opinion, novelty should be clearly stated in this section. Why is interesting to know this model for other basins?

This section presents the state of the art and the previous works in different sort of models in this sort of numerical simulations. The particular problem of sedimentation modelling is difficult to consider and authors have made a wide consideration of different approaches, mainly presenting why CFD models are not the final solution to these sort of scale problems. The main objectives are presented. In this reviewer opinion, this section is adequate.

Study area. This section presents the studied area. In this reviewer opinion, this section together with section 3 should be part of a section called “Materials and Methods”. Apart from this, the section is well presented.

Research Methods. This section presents the model and the main equations, mesh and validation conditions. In this reviewer opinion, it would be interesting to present the boundary conditions considered and the main error in the predictions. How was the calibration model? No details are provided about the calibration of the multiple parameters involved in the modelling and how to determine them.

Optimization analysis of operation scheme. This section is confusing to me. Authors present in the previous section the model, with the validation and the grid and the simulation process, and in this section they present details about the operation scheme, boundary conditions and results of modelling. Some clarifying about these questions would be welcome in the general structure of the paper. I understand that these results and discussion are over different numerical hypothesis, but I do not see any process of optimization in the sense of the action of making the best or most effective use of a situation or resource.

Apart from this, the legends of figures are too long. In this reviewer opinion, legends of figures should be within the text. Furthermore, numbering of this section is wrong, as it passes from 4.1.1. too 3.2

A set of conclusions are provided. In this reviewer opinion, the degree of accomplishment of the objectives proposed and the novelty of the work should be stated in these conclusions. The optimization strategy should also be clearly pointed out in this section.

Author Response

Dear Reviewer:

Thank you for your comments on our paper “Mike 21 Model-based Numerical Simulation of the Operation Optimization Scheme of Sedimentation Basin” (ID: 1629404). First, we would like to extend our heartfelt thanks to you for your valuable comments and suggestions which are very helpful for revising and improving our paper, as well as of guiding significance to our researches. We have studied those comments carefully and made corrections to meet with your approval. Revised portions are marked in blue in the paper.

The main corrections in the paper and the response to the reviewer's comments are as follows:

This section is adequate, with the main objectives of the work and main achievements. Nevertheless, in this reviewer opinion, novelty should be clearly stated in this section. Why is interesting to know this model for other basins?

Response: Thank you very much for your questions, these places are exactly what we overlooked, and the abstract of the paper has been revised and supplemented.

(1) Novelty.

We have revised and added in lines 16-19, the main contents is “Because the prototype size is too large and not easy to analyze, Mike 21 has the advantages of easy input, conversion, analysis, and demonstration of data results, which are flexible and convenient, however, this method has not been used in hydraulic engineering by previous.” The predecessors did not use this method to study the problems in the optimization field of the sedimentation basin, this paper tried to proposes a new scientific and feasible idea.

(2) Why is interesting to know this model for other basins?

Thank you for your question, which has been incorporated into our subsequent research plans. This paper proposes a new scientific and feasible idea, and we will consider the cyclone type, inclined plate type, circular middle ring and other sedimentation basins of hydraulic engineering to our subsequent research.

Study area. This section presents the studied area. In this reviewer opinion, this section together with section 3 should be part of a section called “Materials and Methods”. Apart from this, the section is well presented.

Response: Thank you for your suggestion. The study area and section 3 have been combined into “Materials and Methods”.

Research Methods. This section presents the model and the main equations, mesh and validation conditions. In this reviewer opinion, it would be interesting to present the boundary conditions considered and the main error in the predictions. How was the calibration model? No details are provided about the calibration of the multiple parameters involved in the modelling and how to determine them.

Response: Thank you for your suggestion and questions.

(1) It would be interesting to present the boundary conditions considered and the main error in the predictions.

Thank you very much for your suggestions. We have ignored this place and added it. In 2.2.2. Model establishment and parameter calibration, added the content of Parameter calibration. “The parameters in hydrodynamic module are set using low-level operations; the Drying depth is 0.005 m, the Flooding depth is 0.05 m, the Wetting depth is 0.1 m, and the eddy viscosity coefficient is 0.28; the river bed roughness is Manning coefficient calculation, set is 32 m^1/3/s; initial water level is 53.5 m. The parameters in sediment module, the sedimentation velocity of suspended sediment is selected as flocculation sedimentation, the flocculation condition is 0.01 kg/m³, and the density of sediment is 2650 kg/ m³; for the distribution of suspended sediment in the water body, the critical siltation shear stress is 0.15 N/m². Set up 1 sediment component and 2 bottom beds, bed 1 is soft mud layer, bed 2 is hard mud layer. The scour coefficient of the first layer is 0.00005 kg/m²/s, the second layer is 1 kg/m²/s, and the density of the first bed is 200 kg/m³ and the density of the second bed is 400 kg/m³, given an initial concentration of component 1 of 0.001 kg/m³. The two processes were consistent, and the fitting effect was perfect.”

(2) How was the calibration model? No details are provided about the calibration of the multiple parameters involved in the modelling.

Thank you very much for your suggestions. In 2.2.3. Model validation, we compared the numerical simulation and the measured data, “the fitting error between the simulated and measured sediment concentration values of the measuring station was < 0.084 kg/m³.”

Optimization analysis of operation scheme. This section is confusing to me. Authors present in the previous section the model, with the validation and the grid and the simulation process, and in this section they present details about the operation scheme, boundary conditions and results of modelling. Some clarifying about these questions would be welcome in the general structure of the paper. I understand that these results and discussion are over different numerical hypothesis, but I do not see any process of optimization in the sense of the action of making the best or most effective use of a situation or resource.

Response: Thank you for your suggestion. According to“figure 12, variation of sediment concentration at characteristic points in flood season and non-flood season in different schemes”, it can be seen that the sediment concentration at the outlet increases, but it is still less than the designed outlet sand content of 2 kg/m³. In “figure 13, distribution of local silting in flood and non-flood seasons”, the Scheme III is to lower the outlet water level of the sedimentation basin with the most uniform deposition distribution, which also reduces the clogging of the outlet of the sedimentation basin. The annual design sedimentation volume of the desilting basin of this project is 1.93 million m³, the flood season is four months, and the non-flood season is eight months. The one-year sedimentation volume is calculated proportionally to 1.5 million m³, and the dredging period of the sedimentation basin can be extended. About 3.5 months. This point is supplemented in line 447. The calculation process is

174×(4/12)+150×(8/12)=150 (1)

(193-150)/150×12=3.4399 (2)

Apart from this, the legends of figures are too long. In this reviewer opinion, legends of figures should be within the text. Furthermore, numbering of this section is wrong, as it passes from 4.1.1. to 3.2.

Response: Thank you for your careful examination and suggestion. The legends of figures have been revised and put into the text, and the number has been rewritten and revised.

A set of conclusions are provided. In this reviewer opinion, the degree of accomplishment of the objectives proposed and the novelty of the work should be stated in these conclusions. The optimization strategy should also be clearly pointed out in this section.

Response: Thank you for your suggestion. There is really something wrong with the formulation in the conclusion part. We have revised this part. The revised content is as follows: “4. Conclusions. This research used the sedimentation basin of the Yellow River Diversion Project as the research object, based on Mike 21 model to discuss the simulation of optimization scheme, and compared the three schemes of raising outlet water level, raw water level and lowering outlet water level. And the optimal scheme was determined as the scheme III, the water level at the outlet was lowered by 0.5 meters. The results showed that during the flood and non-flood seasons, the amount of sedimentation during the high-water outlet operation (Scheme I) increased by 180000 m³ and 150000 m³, respectively, compared with the low-water outlet operation (Scheme III). Combining with the distribution of sediment deposition, it is concluded that when the outlet water level is lowered, the distribution of sediment deposition in the sedimentation basin is more uniform, the sedimentation condition in the sedimentation basin is also improved, the utilization ratio of channel is higher, and prolong the period of silting removal about three months. This research provides a scientific and feasible idea for efficient utilization of sedimentation basin, the results are easy to observe and compare. However, only considers the channel sedimentation basin and does not consider the swirling type, inclined plate type, and circular middlering and other sedimentation basins of hydraulic engineering, and further research is needed.”

We tried our best to improve the manuscript and made some changes in the manuscript. These changes will not influence the content and frame work of the paper. And we marked the changes in blue in revised paper. We appreciate for Reviewer’ warm work earnestly, and hope that the correction will meet with approval. Once again, thank you very much for your comments and suggestions.

Yours sincerely

Meng Chen

Reviewer 2 Report

This paper provides a research of a simulation model of the sedimentation basin 1# canal, which was developed using Mike 21 software to analyze its water and sediment characteristics and conditions in different periods. Three types of sedimentation basin operation schemes were targeted, the sedimentation changes and sedimentation law of the 1# canal were evaluated in each scheme, and the sedimentation effects were compared. The results show that in conditions of different incoming water and sediment and diversion timings during the flood and non-flood seasons, the sedimentation basin adopts an operation scheme to lower the outlet water level, and the siltation volumes are 180000 and 150000 m³ lower than the high-outlet water levels, respectively. Remarks: The paper is a case study. To make paper more appealing, the explanation what is new in approach which author uses will be helpful. In the abstract, it is weak, it is not clear which area was studied and which methods were used. It gives the reader no information as to what to expect in the paper. Please consider both the novelty and the relevance of your objectives of your paper. Line 424: Replace the * by the multiplication symbol.

Author Response

Dear Reviewer:

The main corrections in the paper and the response to the reviewer's comments are as follows:

Response: Thank you for your careful examination and suggestion.

(1) To make paper more appealing, the explanation what is new in approach which author uses will be helpful.

Thank you for your suggestion. We have revised and added in lines 16-19, the main contents is “Some of the previous studies on the optimization problem of the CFD model, but the final CFD results cannot provide any form of analytical expressions and only a numerical solution on a limited number of discrete points; additionally, there are certain calculation errors. Some researchers optimize the sedimentation basin by adjusting the baffle to optimize the sedimentation basin, it is only suitable for small-size sedimentation basins, not suitable for hydraulic engineering. Considering this, the software Mike 21 has been used owing to its advantages, including easy data input, data conversion and analysis, and the presentation of the results, which makes it quite flexible and convenient.”

Mike 21 is not a new method, but few researchers have used Mike 21 model to study and analyze the optimization of sedimentation basin, and even fewer researchers have applied Mike 21 to the optimization of sedimentation basin in hydraulic engineering. This paper combines CAD, SMS and Mike 21 software for simulation calculation to provide a new idea.

(2) In the abstract, it is weak, it is not clear which area was studied and which methods were used.

Thank you for your suggestion. We have revised and added this part. “Abstract: The sedimentation basin is an important part of the hydraulic engineering. Because the prototype size is too large and not easy to analyze, Mike 21 has the advantages of easy input, conversion, analysis, and demonstration of data results, which are flexible and convenient, however, this method has not been used in hydraulic engineering by previous. This research used the sedimentation basin of the Yellow River Diversion Project as the research object, a simulation model of the sedimentation basin 1# canal was developed using Mike 21 software to analyze its water and sediment characteristics and conditions in different periods. Using numerical simulation methods Three types of sedimentation basin operation schemes were targeted, the sedimentation changes and sedimentation law of the 1# canal were evaluated in each scheme, and the sedimentation effects were compared. The results show that in conditions of different incoming water and sediment and diversion timings during the flood and non-flood seasons, the sedimentation basin adopts an operation scheme to lower the outlet water level, and the siltation volumes are 180000 and 150000 m³ lower than the high-outlet water levels, respectively. Moreover, its siltation status will be significantly improved, which can effectively extend the service life of the sedimentation basin, prolong the period of silting removal about 3.5 months, and provide a scientific basis and reference for the optimization of the operation mode of the sedimentation basin in other hydraulic engineering.”

Mike 21 numerical simulation method is used in this study, and the research field is suitable for hydraulic engineering.

(3) Please consider both the novelty and the relevance of your objectives of your paper.

The efficient use of the sedimentation basin is of great significance to hydraulic engineering. This paper combines CAD, SMS and Mike 21 software for simulation calculation.

Meanwhile, previous studies have conducted in-depth research on the characteristics of water and sand movements in sedimentation basins. However, the final CFD results cannot provide any form of analytical expressions but only a numerical solution on a limited number of discrete points; additionally, there are certain calculation errors. By adjusting the baffle to optimize the sedimentation basin, it is only suitable for small-size sedimentation basins. Considering this, we used the software Mike 21. The predecessors did not use this method to study the problems in the optimization field of the sedimentation basin, this paper tried to proposes a new scientific and feasible idea.

(4) Line 424: Replace the * by the multiplication symbol.

You are really responsible, we have revised it.

Yours sincerely

Meng Chen

Round 2

Reviewer 2 Report

This paper provides a research of a simulation model of the sedimentation basin 1# canal, which was developed using Mike 21 software to analyze its water and sediment characteristics and conditions in different periods. Three types of sedimentation basin operation schemes were targeted, the sedimentation changes and sedimentation law of the 1# canal were evaluated in each scheme, and the sedimentation effects were compared. The results show that in conditions of different incoming water and sediment and diversion timings during the flood and non-flood seasons, the sedimentation basin adopts an operation scheme to lower the outlet water level, and the siltation volumes are 180000 and 150000 m³ lower than the high-outlet water levels, respectively. Remarks: Line: 443: The choice of reference should be supplemented with respect to the multidimensional comparative analysis in the futher research, including swirling type, inclined plate type, and circular middle-ring and other sedimentation basins of hydraulic engineering [eg. Ref. Pietrucha-Urbanik, K. Multidimensional comparative analysis of water infrastructures differentiation. In Proceedings of the Conference on Environmental Engineering IV, Lublin, Poland, 3–5 September 2012; pp. 29–34]. Line 597: If possible give some more details about a scientific and feasible idea for efficient utilization of sedimentation basin.

Author Response

Dear Reviewer:

Thank you for your letter and comments concerning our manuscript entitled “Mike 21 Model-based Numerical Simulation of the Operation Optimization Scheme of Sedimentation Basin” (ID: 1629404) again. Those comments are valuable and very helpful. We have read through comments carefully and have made corrections. Based on the instructions provided in your letter, we uploaded the file of the revised manuscript. Revisions in the text are shown using blue highlight for additions.

The main corrections in the paper and the response to the reviewer's comments are as follows:

This paper provides a research of a simulation model of the sedimentation basin 1# canal, which was developed using Mike 21 software to analyze its water and sediment characteristics and conditions in different periods. Three types of sedimentation basin operation schemes were targeted, the sedimentation changes and sedimentation law of the 1# canal were evaluated in each scheme, and the sedimentation effects were compared. The results show that in conditions of different incoming water and sediment and diversion timings during the flood and non-flood seasons, the sedimentation basin adopts an operation scheme to lower the outlet water level, and the siltation volumes are 180000 and 150000 m³ lower than the high-outlet water levels, respectively. Remarks: Line: 443: The choice of reference should be supplemented with respect to the multidimensional comparative analysis in the further research, including swirling type, inclined plate type, and circular middle-ring and other sedimentation basins of hydraulic engineering [eg. Ref. Pietrucha-Urbanik, K. Multidimensional comparative analysis of water infrastructures differentiation. In Proceedings of the Conference on Environmental Engineering IV, Lublin, Poland, 3–5 September 2013; pp. 29–34]. Line 597: If possible give some more details about a scientific and feasible idea for efficient utilization of sedimentation basin.

Response: We appreciate your reference and suggestions very much.

We have carefully read and studied your recommended article Multidimensional Comparative Analysis of Water Infrastructure Differentiation. This article is logically clear, linguistically accurate, and methodologically rigorous. Thank you for providing us with an excellent reference. The multi-dimensional comparative analysis method used in this paper provides a good idea for our further research on the analysis of hydro-engineering sedimentation basin such as swirl type, inclined plate type, circular middle ring, etc. For the selected grouping methods of the Ward agglomeration methods, the k-means and the Kohonen neural modelling mentioned in the article, these methods will be considered in comparison of various parameters of the sedimentation basin in the future. And we will also consider comparing Mike 21 simulation and multidimensional comparative analysis (WAP) to determine which form of sedimentation basin is the best in hydraulic engineering, which will provide certain reference for the design and construction of sedimentation basin in hydraulic engineering.

We have revised and added in lines 448-449, the main contents is “Through the automatic control technology of water level, the outlet water level can be adjusted by using the outlet sluice.” This research proposed the scheme of adjusting water level to optimize sedimentation basin, water level automatic control technology and water return sluice can be used in the planning and construction of hydraulic engineering. In this research, the scheme to reduce the water level of 0.5 m is achievable. The specific water level will be changed in the actual operation of the hydraulic project also needs to consider many factors, such as human resource consumption, cost, land occupation resources and ecological environment impact.

Your letter and careful review have helped to make our research clearer and more comprehensive. We appreciate for Reviewer’s warm work earnestly, and hope that the correction will meet with approval. Once again, thank you very much for your comments and suggestions.

Yours sincerely

Meng Chen