A Novel Method for Analyzing Sandbar Distribution in Shelf-Type Tidal Deltas Using Sediment Dynamic Simulation

Round 1

Reviewer 1 Report (Previous Reviewer 1)

Comments and Suggestions for Authors

In the revised manuscript titled "A Novel Method for Analyzing Sandbar Distribution in Shelf Type Tidal Deltas Using Sediment Dynamic Simulation," the authors have successfully addressed the primary weakness of the original paper: the lack of correlation between the characteristics of Vym strata and those generated by the simulation. Considering the limitations of the available dataset, as detailed in the response letter, the dimensions of Vym formation tidal flats (average length, width, and thickness) were incorporated into the analysis to facilitate a correlation between real and simulated data. This enhancement has significantly improved the value of the work, and it is recommended for consideration for publication.

Comments on the Quality of English Language

Minor English editing required.

Author Response

Thank you for your kind work. We appreciate your valuable suggestions during the revision process!

Reviewer 2 Report (New Reviewer)

Comments and Suggestions for Authors

This paper takes the Jurassic strata in the region of northern part of West Siberian Basin as the research object, and conducts numerical simulation based on sedimentary dynamics for the shelf type tidal delta sedimentation formed under the tectonic background of "one uplift zone between two depressions". In addition, tidal amplitude and initial water level were selected for different hydrodynamic factors to study the main controlling factors of shelf type tidal delta sedimentation.

                 This paper is presenting several interesting results, though, it is necessary to make several revisions in order to be published in the journal as listed below. Especially the explanations for the input conditions in the numerical model is highly unsatisfactory.

 

1.      Although Delft3D has been widely applied to many places and situations, some validation results must be shown for this particular study area, in terms of quantities such as water level, velocity and morphology change.

2.      P.2 Line 77 “two categories”: The description on the hydraulic modeling is not correct. In general, a morphological model consists of (1) hydrodynamic modelling + (2) sediment movement modeling + and (3) sediment mass conservation equation to calculate bed elevation change. For (1) and (2) compartments, there are so variety of the modeling methods, not only “two categories” as mentioned in the paper. Much more thorough explanations are required in this regard.

3.      Figure 1: For those who are not familiar with this study area, the location of the target area is not clear in this map. Put a map of Rosia so that the location of the study area is more understandable.

4.      The relationship between Figure 1 and Figure 2 is not understood. Show the computational domain depicted in Figure 2 in Figure 1.

5.      The explanation on the quantities shown in Table 1 and Table 2 is unsatisfactory. All of the input parameters are time-dependent, of course. Thus, it is necessary to make more thorough descriptions, e.g., averaged quantity? Or what is the return period of the input conditions?

6.      Table 2: The wave period is missing in the table?

7.      Table 2 “water level”: The definition is totally unclear. What is the datum elevation? Is it the water level above the mean sea level? Define it more clearly. In addition, the water changes so widely from 1.0m to 45m? From dry season to rainy season? It has so big variability in the river?

Author Response

Comment 1: Although Delft3D has been widely applied to many places and situations, some validation results must be shown for this particular study area, in terms of quantities such as water level, velocity and morphology change.

Thank you. In this paper, the fifth section Discussion, the validation of the simulation results is carried out, which reflects the correlation of Vym strata and simulation result, as evident in lines 414 to 447. Based on the available data, we have conducted a statistical comparative analysis of the three-dimensional configuration characteristic parameters of both the actual sand bodies within the Vym strata of the study area and those formed via simulation. Furthermore, a direct comparison was made between the actual sedimentary conditions of the sand bodies in the study area and those simulated by the model, thereby validating its reliability. Nonetheless, due to the paucity of drilling wells in the Northern part of West Siberian Basin, particularly with only eight drilling wells in the study area, the scarcity of available data hampers an extensive comparison between simulations and reality for the majority of areas outside the study area. The dearth of drilling wells significantly complicates the exploration and development of target strata in the study area. Consequently, this research endeavors to employ the numerical simulation method in sediment dynamic to investigate the depositional evolution of the Vym strata within the study area and analyze the main-controlling factors of sedimentation. It aims to provide a predictive framework for guiding future well placement strategies and reservoir development plans, thereby contributing to enhanced understanding and exploitation of the gas reservoirs in study area in this challenging context.

 

Comment 2: P.2 Line 77 “two categories”: The description on the hydraulic modeling is not correct. In general, a morphological model consists of (1) hydrodynamic modelling + (2) sediment movement modeling + and (3) sediment mass conservation equation to calculate bed elevation change. For (1) and (2) compartments, there are so variety of the modeling methods, not only “two categories” as mentioned in the paper. Much more thorough explanations are required in this regard.

Thank you. We agree with this comment. We have revised the description of numerical simulation methods of sediment dynamics. As shown in lines 75 to 82.

 

Comment 3: Figure 1: For those who are not familiar with this study area, the location of the target area is not clear in this map. Put a map of Rosia so that the location of the study area is more understandable.

Thank you. We have revised the Figure 1 and add a map of Russia in Figure 1(a) to show the location of study area.

 

Comment 4: The relationship between Figure 1 and Figure 2 is not understood. Show the computational domain depicted in Figure 2 in Figure 1.

Thank you. The horizontal surface area of the model corresponds to the area of the paleogeograph-ic map (Figure 1(a)), we enhanced the description of this part, as evident in lines 146 to 151.

 

Comment 5: The explanation on the quantities shown in Table 1 and Table 2 is unsatisfactory. All of the input parameters are time-dependent, of course. Thus, it is necessary to make more thorough descriptions, e.g., averaged quantity? Or what is the return period of the input conditions?

Thank you. We agree with this comment. We revised the explanation of the input parameters, as shown in lines 178 to 184.

 

Comment 6: Table 2: The wave period is missing in the table?

Thank you. We added the description of wave period, as shown in line 168.

 

Comment 7: Table 2 “water level”: The definition is totally unclear. What is the datum elevation? Is it the water level above the mean sea level? Define it more clearly. In addition, the water changes so widely from 1.0m to 45m? From dry season to rainy season? It has so big variability in the river?

Thank you. We revised the description of the definition of water level, as evident in lines 162 to 167. To investigate the impact of water level height on the development of sand bodies in the study area, a relatively extreme value for high water level conditions is adopted. This choice also aligns with the scenario of widespread marine transgression that occurred during the later Jurassic period. The rivers come from the Ural Mountains, the Taimyr region, and the Siberian craton, and rivers flow down from heights into the ocean area in the center of the basin, and the rise in water level will only gradually submerge the land area around the basin under the surface of the sea, without affecting the rivers.

Round 2

Reviewer 2 Report (New Reviewer)

Comments and Suggestions for Authors

I confirmed that the authors have made proper revisions for the items I pointed out during the first review process. The paper can be now published in the journal.

This manuscript is a resubmission of an earlier submission. The following is a list of the peer review reports and author responses from that submission.

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

The resubmitted manuscript entitled “Study on Distribution Law of Sand Bodies and Interlayers in Shelf Type Tidal Delta Based on Numerical Simulation of Sedimentary Dynamics” is relevant with the scope of magazine.

The cited references cover the scientific field of the presented work quite well. Eight out of 32 references are written within the last 5 years.

The introduction has been significantly revised, and the geological setting is presented in lines 66-85. Figure 1 is still poorly presented (fig. 1a does not have a reference in the text) and needs to be improved since it provides information on the Vym time strata. A more detailed description is required for the specific unit, as the authors declare that their study focuses on that specific unit. Additionally, expect from the paleogeographic map presented in the work of Shemin G. et al. (2019), the authors also provide well-log data that could be also used in the present manuscript in order to enhance our understanding of the sedimentological context of the Vym unit.

In this context, it is advised that the geological setting is described in a separate sub-section where the improved palaeogeographic map and the stratigraphic column are shown.

The methodological approach is the same as presented in the initial manuscript. Most of the suggestions have been answered.  Regarding the statistical control of the results, the authors compare the outcomes of the various scenarios with the basic model (Tidal amplitude 6.0m and water level 1m). This cannot be regarded as statistical control; it is more of a comparison between the implemented scenarios and an initial configuration of the model. At this point, the major weakness of the study is located. While the authors refer to the Vym strata and the effort to reconstruct the sedimentological conditions of the formation, there is no clear correlation between the sedimentological attributes of Vym formation (e.g., bars and channels distribution, the thickness of Vym formation sands and interlayers, etc.) with the outcomes of the simulation. The only apparent connection is the use of the Vym paleo-geographic map as an input for the paleo-bathymetry of the basin. In this context, the results of the analysis are weakened and downgraded to a simple application of a numerical model software (Delft3D). As an example of a statistical control approach, the authors that developed the specific software have statistically checked the validity of the software using the case of IJmuiden, the seaport of Amsterdam G.R. Lesser et al. (2004).

The discussion, as indicated in the author’s reply, is included in the results section.

More comments and notes for the improvement of the manuscript can be found in the attached file.

The use of English is acceptable, but there are some minor syntax errors (see attached file).

To conclude, the presented work needs a major improvement in the statistical control of the simulation results. 

 

Comments for author File: Comments.pdf

Comments on the Quality of English Language

Minor correction required.

Author Response

The resubmitted manuscript entitled “Study on Distribution Law of Sand Bodies and Interlayers in Shelf Type Tidal Delta Based on Numerical Simulation of Sedimentary Dynamics” is relevant with the scope of magazine.

 

The cited references cover the scientific field of the presented work quite well. Eight out of 32 references are written within the last 5 years.

 

The introduction has been significantly revised, and the geological setting is presented in lines 66-85. Figure 1 is still poorly presented (fig. 1a does not have a reference in the text) and needs to be improved since it provides information on the Vym time strata. A more detailed description is required for the specific unit, as the authors declare that their study focuses on that specific unit. Additionally, expect from the paleogeographic map presented in the work of Shemin G. et al. (2019), the authors also provide well-log data that could be also used in the present manuscript in order to enhance our understanding of the sedimentological context of the Vym unit.

 

In this context, it is advised that the geological setting is described in a separate sub-section where the improved palaeogeographic map and the stratigraphic column are shown.

Thanks. We added a section in order to describe the region setting. And we added more detailed description for the Vym time strata. We enlarged Figure 1(a) enough to make it clear and added a stratigrafic chart as shown in Figure 1(b). As shown in line 101 to 135.

 

The methodological approach is the same as presented in the initial manuscript. Most of the suggestions have been answered.  Regarding the statistical control of the results, the authors compare the outcomes of the various scenarios with the basic model (Tidal amplitude 6.0m and water level 1m). This cannot be regarded as statistical control; it is more of a comparison between the implemented scenarios and an initial configuration of the model. At this point, the major weakness of the study is located. While the authors refer to the Vym strata and the effort to reconstruct the sedimentological conditions of the formation, there is no clear correlation between the sedimentological attributes of Vym formation (e.g., bars and channels distribution, the thickness of Vym formation sands and interlayers, etc.) with the outcomes of the simulation. The only apparent connection is the use of the Vym paleo-geographic map as an input for the paleo-bathymetry of the basin. In this context, the results of the analysis are weakened and downgraded to a simple application of a numerical model software (Delft3D). As an example of a statistical control approach, the authors that developed the specific software have statistically checked the validity of the software using the case of IJmuiden, the seaport of Amsterdam G.R. Lesser et al. (2004).

Thanks. We revised the description of the results and discussion as shown in line 205 to 207, line 290, line 388 and line 422 to 424.

 

Minor corrections:

Line 13 to line 15 in last version: Confusing, has to be rephrased.

Thanks. We revised the sentences: During the Middle Jurassic period, the northern part of West Siberian Basin was characterized by a shallow marine shelf sedimentary environment. In the central region of this basin, a typical tectonic uplift zones developed, forming a tectonic background of "one uplift zone between two de-pressions". As shown in line 13 to 16 in the new version.

 

Line 49 in last version: fluvial system?

Thanks. We changed fluvial to fluvial system at line 45 in new version.

 

Line 80 in last version: Why to you refer to a "special tectonic setting"? One uplift and two depressions correspond probabbly to a horst and graben configuration which is typical in many settings, some of the m formed due to extension tectonics in Jurassic (e.g Møller, Jens & Rasmussen, Erik. (2003). Middle Jurassic - Early Cretaceous rifting of the Danish Central Graben. Geological Survey of Denmark and Greenland Bulletin. 1. 10.34194/geusb.v1.4654. )

Thanks. We deleted “special”.

 

Correct the reference syntax.

Thanks. We revised the citation problems. As shown in line 83 to line 94 and line 117 in the new version.

 

Figure 1(b) in last version: Add a color scale bar in order to provide information about the bathymetry.

Thanks. Adopted in figure 2.

Reviewer 2 Report

Comments and Suggestions for Authors

Dear Authors,

referring to your article “Study on Distribution Law of Sand Bodies and Interlayers in Shelf Type Tidal Delta Based on Numerical Simulation of Sedimentary Dynamics”, I read the response to my comments, and noted that my suggestions were only partially accepted.

However, the method you propose seems to be valid and interesting, it scientifically sounds, and I don't want to hinder the article’s publication. I will propose to the editor to accept your work, after minor revision.

In fact, in my opinion some adjustments are still needed.

1) General organization: it was improved, and the MS is now better readable. Please check the English (language and style can be improved). Also check the style for in-text citations and references list.

2) Abstract, introduction: aims and methods, as well as results, are now clearer: just please try to simplify it

3) Please consider to add a stratigrafic chart to summarize the study from Shemin et al., or to enlarge Figure 1 enough to make the geology/stratigraphy readable.  

4) If the aim was to propose a model for sedimentary features described by Shemin et al, the sedimentary bodies you are referring to should be figured as they appear in the field (or in geological profiles). Anyway, a comparison with real geological/sedimentological data should be proposed, or at least postponed to future studies. Such a comparison is still lacking.

Best Regards

The reviewer

Author Response

 referring to your article “Study on Distribution Law of Sand Bodies and Interlayers in Shelf Type Tidal Delta Based on Numerical Simulation of Sedimentary Dynamics”, I read the response to my comments, and noted that my suggestions were only partially accepted.

 

However, the method you propose seems to be valid and interesting, it scientifically sounds, and I don't want to hinder the article’s publication. I will propose to the editor to accept your work, after minor revision.

 

In fact, in my opinion some adjustments are still needed.

 

1. General organization: it was improved, and the MS is now better readable. Please check the English (language and style can be improved). Also check the style for in-text citations and references list.

Thanks. We revised some English problems and the citation problems. As shown in line 83 to line 94 and line 117

 

2. Abstract, introduction: aims and methods, as well as results, are now clearer: just please try to simplify it.

Thanks. We simplified the abstract and introduction as shown in line 10 to 34 and line 38 to 100.

 

3. Please consider to add a stratigrafic chart to summarize the study from Shemin et al., or to enlarge Figure 1 enough to make the geology/stratigraphy readable.

Thanks. We add the region setting in the section 2 with a stratigrafic chart as shown in Figure 1(b). In addition, we enlarged Figure 1(a) enough to make it clear.

 

4. If the aim was to propose a model for sedimentary features described by Shemin et al, the sedimentary bodies you are referring to should be figured as they appear in the field (or in geological profiles). Anyway, a comparison with real geological/sedimentological data should be proposed, or at least postponed to future studies. Such a comparison is still lacking.

Thanks. We revised the description of the results and discussion as shown in line 205 to 207 and line 422 to 424.

Round 2

Reviewer 1 Report

Comments and Suggestions for Authors

The majority of the minor issues in the revised manuscript have been addressed. However, the major weakness of the work, namely the statistical control of the results, which was highlighted in the initial review and also in the revised versions, has not yet been addressed.

Comments on the Quality of English Language

Minor language editing required.

Author Response

The majority of the minor issues in the revised manuscript have been addressed. However, the major weakness of the work, namely the statistical control of the results, which was highlighted in the initial review and also in the revised versions, has not yet been addressed.

Thanks. In Section 3.4 of the article, we have added a discussion on validating the effectiveness of our base model results through statistical control methods, as shown in lines 190 to 208. Grounded in existing research data on actual formations, we propose an investigative framework for the shelf type tidal delta deposits of the Vym time in study area. Looking ahead, with the acquisition of more research data, we anticipate further refinement and optimization of the model.

Round 3

Reviewer 1 Report

Comments and Suggestions for Authors

The second revision of the paper has been improved. However, there is still no clear correlation of the Vym strata, which according to the authors, is the target strata, with the results of the model. The palaeotopography of the Vym strata is used as an input for the initial DEM model, but the various scenarios examined by the authors are not compared with the simulated Vym strata deposits. In this context, unfortunately, the paper is not recommended for publication in JMSE.

Comments on the Quality of English Language

Minor editing of English language required.