Quantitative Study of Climatic and Anthropogenic Contributions to Streamflow and Sediment Load in the Yangtze River, China
Round 1
Reviewer 1 Report
In this study, authors addressed that variation in Suspended Sediment Discharge (SSD) and Water Discharge (WR) along the Changjiang River，and then discussed which factors can be dominant over SSD and WR. The results found that climate change was responsible for the increased WR, and human will play a key on decline SSD. The present work should have potential meaning for international society. However, some revision should be done before acceptance. First. Introduction part wants to add much references about associated work about SSD and WR of the Yangtze River, which can have further understanding of SSD and WR along Changjiang (See Dai et al., Geomorphology, 2016, 268, 123-132.; Wei et al., Quaternary International, 2014, 336, 98-107; Dai Z.J.,2021.Changjiang riverine and estuarine hydro-morphodynamic processes,In the Context of Anthropocene Era. Springer Press. Dai et al., Journal of Hydrology, 2018, 566, 719-734). Secondly, while results can be well done, discussion part should have detailed analysis. E.g. riverbed erosion, lake changes and extreme flood can have some impacts on WR and SSD (See Dai et al., J.H., 2018; Yu et al., Journal of Hydrology, 562, 254-266). Moreover, Figures wants to be revised. E.g. Figure 2 had no x-label.
Author Response
Please see the attachment.
Author Response File: 
Author Response.doc
Reviewer 2 Report
Impacts of climate change and human activities on river hydrology are a research hotspot of water science. The Yangtze River is among the world’s largest rivers in terms of runoff and sediment load. The present submission aims to quantify the effects of precipitation change and human activities on the annual runoff and sediment load along the mainstream of the Yangtze River during the recent 60 years. Although some similar studies have been done in previous years, this submission exhibits more detailed and updated data. It helps to add our knowledge about the impacts of climate change and human activities on river systems. However, moderate revision is needed before consideration of acceptance.
Minor comments and suggestions:
“Daily discharge” and “daily precipitation”: You seemly did not show daily data. You showed annual data which were based on daily measurements, did you?
“Natural period”: As you may know, the period 1961-1980 was not a real natural period. For example, about 70 high dams was constructed in this period (see Fig. 2 of you Reference 37 (Yang et al., 2018)). So, you had better replace “Natural period” with Quasi-natural period” or “Quasi-natural condition period”.
Lines 21 and 23: The word “other” is unnecessary, because you use “except for”.
Lines 23-25: “Human activities are the main reason for the reduced annual runoff at the other five stations during the impacted period, while climate change is the dominant factor for the increased runoff at Datong stations.” Why the runoff trend at Datong is opposite to the trends at the upper stations? Is it because the precipitation-increased runoff in the basin of Lake Poyang exceeded the human-decreased runoff in the upper reaches? You had better explain this in the abstract as well as in the main text.
Line 40: You can cite an updated paper after “coastal erosion” (Yang, SL, X. Luo, S. Temmerman, M. Kirwan,T. Bouma, K. Xu, S. Zhang, J. Fan, B. Shi, H. Yang, YP Wang, X. Shi, S. Gao, 2020. Role of delta-front erosion in sustaining salt marshes under sea-level rise and fluvial sediment decline. Limnology and Oceanography. 65 (9), 1990–2009. doi: 10.1002/lno.11432).
Line 62: “215x108 m3”. Note: The maximum storage capacity of the Three Gorges Reservoir is 39.3 km3 (see your Reference 36).
Lines 67-81: Please check if you have missed Reference 42 in this paragraph.
Line 89: You may need to add “change” after “climate”.
Lines 487-489: “The variation characteristics of runoff and sediment load in the whole river basin and the reasons are analyzed by comparing the impacted period (1981-2020) with the natural period (1961-1980) in this study.” This sentence is about method and is redundant in the Conclusion section.
Lines 495-496: Shashi and Jianli stations are not included in the Figures and Tables.
Lines 491-496: “The runoff from the upper reaches to the estuary increased from 1981-2000 except for Cuntan station and reduced significantly during 2001-2020 except for Datong station. The sediment load decreased in the mainstream except at Zhutuo station from 1981 to 2000, and the decreased trend was further enhanced from 2001 to 2020. The effects of precipitation on the runoff show an increasing trend along the Yangtze River except at Shashi and Jianli stations, while the effects of runoff on sediment load decrease from Zhutuo station to Luoshan station.” I suggest some revision for this paragraph as follows.
The runoff in the mainstream of the Yangtze River increased (slightly ?) during the period 1981-2000 except for Cuntan station, and then reduced significantly (?) during 2001-2020 except for Datong station. The sediment load decreased from 1981 to 2000 except for Zhutuo station, and enhanced decreasing trend was found at all stations (?) from 2001 to 2020. The effects of precipitation on the runoff along the Yangtze River show a downstream increasing trend except for Shashi (?) and Jianli (?) stations, while the effects of runoff on sediment load show a downstream decreasing trend from Zhutuo to Luoshan station.
In this revised paragraph, the question marks remind you to check the correctness.
Lines 505 and 507: Check the grammar.
Line 511: You may need to include delta erosion.
Conclusions: In this section, you should address the main findings about your objectives. Unfortunately, you did not show the result about Objective 3 (to estimate the errors for the regression-based prediction).
Fig. 1a: Why you just indicate Yichang and Hankou stations?
Fig. 2: You missed scale numbers, did you?
Fig. 4-5: Can you show the significant levels of the increasing trends, even if they are >0.05?
Fig. 10: What does the word Sgriculture mean? Agriculture?
References 32 and 64 are the same publication.
Author Response
Please see the attachment.
Author Response File: Author Response.doc
Reviewer 3 Report
Review Water 1860635, Quantitative study of climatic and anthropogenic contributions to streamflow and sediment load in the Yangtze River, China by Qian et al.
This paper describes an analysis of 40 year data on runoff and sediment load in the Yangtze River, distinguishing between climatological and anthropogenic impacts. The analysis is useful, but not very new. I have numerous detailed comments (see below) and a few major ones:
1. It would be helpful to explain how the data collected, and how accurate – it is not easy to collect reliable data in such a big river!!
2. The authors love to present their results in many digits, suggesting an accuracy they cannot justify. This must be corrected.
3. The relation between runoff and sediment load is generally not linear. So why use a linear analysis?
4. Please provide the regression equations.
5. The English must be improved. Many strange sentences – many statements and conclusions are illegible.
Major revision is required.
Abstract and elsewhere in text: refrain from apparent accuracies – omit the decimals in the numbers (39.6% should be 40%)
61: “supplemented” ?? what do you mean, wrong word. In fact, entire sentence is illegible. Is this the total volume per year, or the volume in the reservoir, …???
74: why human with capital?
76/77: “is still lack” wrong English
77: “Previous studies assume that the runoff change, regardless of decrease or increase, is solely caused by climate change to separate the influence of climate change and human activities on the change in sediment load” Nonsense sentence
86: why linear analysis – relation sediment load and runoff are generally not linear.
89: climate change?
94: Above you say Yangtze is the longest of Asia, so also of China….
96/97: 9th in globally ???? wrong English
97: “mainstream” should be river basin
103: “scatter” ????
109: Please provide evidence or reference for ignoring bed load
117: omit “territory with””
120: six sub-regimes?? Above you say three….
136: “abrupt points” what is that??
141: “outside distractions” what is that???
149: “Due to the large scale of human activities in rivers worldwide” omit this
Fig. 2: What do the data represent? Yangtze results? If not, figure is superfluous, and can be omitted
186: “might significantly underestimate human contribution to sediment load changes“ seems quite crucial – so why??
189: “By ignoring human effects, the contribution of human activities will 189 be underestimated” omit sentence.
205: what is model fitting degree?
206: In other words??
219-224: Too long sentence, illegible. Please rewrite
Fig 3: what is unity on vertical axis? And what do Statistics UF and Statistics UB mean – not defined. Further, what is the significance of the crossings in the graphs with the years indicated (2008, 2002, etc.) Please explain.
I would appreciate graphs with the original data.
235: Use rounded numbers – you suggest accuracies you cannot justify.
245: also for precipitation
253: “The rainfall varies slightly from period to period” what do you mean? The rainfall varies, or which periods? ….
Table 2: Precipitation variation …. What is this, the standard deviation from the trend??
262: “With the intensifying human activities and the climate changes, the runoff and the sediment load in the Yangtze River Basin have changed significantly” – this is what you wish to show, no? So do not start with this conclusion …
Fig. 5: The red dotted trend line is misleading, as you wish to emphasize a discontinuity in trend between the two periods. Please omit.
It would be illustrative to present scatter plots between runoff and sediment load for all stations, distinguishing between the natural and impacted periods. Well you did in Fig 6 and 7 for the natural period, but not for the impacted period. I think you should start with these figures, and only then start your statistical analyses.
Table 3: Omit all numbers after decimal point – your data are not accurate enough.
306: Why poor correlation? Not difficult to imagine.
315: Please provide the regression equations, with its coefficients in Table 4.
319: “along the way” which way?
324: Yes, because relations are not linear!!
341: Reconstructed from precipitation data and regression equation, I presume. If so, say this explicitly, don’t let the reader guess what you are doing.
364-366: What a strange way of saying. You want to say: In spite of the climate change induced increase in precipitation, the river runoff decreased, which must be attributed to human interventions.
377: “nevertheless” should read: would have
388: “renewed” What do you mean???
402 (and before): present data on sand mining and explain about soil conservation – estimate its effect
411: does this volume of sediment accumulation in the reservoirs agree with your own analyses? Please elaborate quantitatively.
415-420: I do not understand this para. Above you conclude from your data that runoff has increased – here you say that we cannot ignore water use. Please explain (quantitatively). Fig. 10: how much in comparison to the runoff
434: See comment above. Please compare data with natural flux to put things into perspective.
444: “… in a certain.” ???
446: “since 1954” ???
Section 5.3: Very strange to start with discussion of your statistical analysis, and then present the standard deviation etc. Please re-organize, present all statistical evidence first, and then evaluate.
Author Response
Please see the attachment.
Author Response File: Author Response.doc
Round 2
Reviewer 3 Report
Review Water 1860635, Quantitative study of climatic and anthropogenic contributions to streamflow and sediment load in the Yangtze River, China by Qian et al.
This paper describes an analysis of 40 year data on runoff and sediment load in the Yangtze River, distinguishing between climatological and anthropogenic impacts. The analysis is useful, but not very new. I have numerous detailed comments (see below) and a few major ones:
1. It would be helpful to explain how the data collected, and how accurate – it is not easy to collect reliable data in such a big river!!
2. The authors love to present their results in many digits, suggesting an accuracy they cannot justify. This must be corrected.
3. The relation between runoff and sediment load is generally not linear. So why use a linear analysis?
4. Please provide the regression equations.
5. The English must be improved. Many strange sentences – many statements and conclusions are illegible.
Major revision is required.
Abstract and elsewhere in text: refrain from apparent accuracies – omit the decimals in the numbers (39.6% should be 40%)
61: “supplemented” ?? what do you mean, wrong word. In fact, entire sentence is illegible. Is this the total volume per year, or the volume in the reservoir, …???
74: why human with capital?
76/77: “is still lack” wrong English
77: “Previous studies assume that the runoff change, regardless of decrease or increase, is solely caused by climate change to separate the influence of climate change and human activities on the change in sediment load” Nonsense sentence
86: why linear analysis – relation sediment load and runoff are generally not linear.
89: climate change?
94: Above you say Yangtze is the longest of Asia, so also of China….
96/97: 9th in globally ???? wrong English
97: “mainstream” should be river basin
103: “scatter” ????
109: Please provide evidence or reference for ignoring bed load
117: omit “territory with””
120: six sub-regimes?? Above you say three….
136: “abrupt points” what is that??
141: “outside distractions” what is that???
149: “Due to the large scale of human activities in rivers worldwide” omit this
Fig. 2: What do the data represent? Yangtze results? If not, figure is superfluous, and can be omitted
186: “might significantly underestimate human contribution to sediment load changes“ seems quite crucial – so why??
189: “By ignoring human effects, the contribution of human activities will 189 be underestimated” omit sentence.
205: what is model fitting degree?
206: In other words??
219-224: Too long sentence, illegible. Please rewrite
Fig 3: what is unity on vertical axis? And what do Statistics UF and Statistics UB mean – not defined. Further, what is the significance of the crossings in the graphs with the years indicated (2008, 2002, etc.) Please explain.
I would appreciate graphs with the original data.
235: Use rounded numbers – you suggest accuracies you cannot justify.
245: also for precipitation
253: “The rainfall varies slightly from period to period” what do you mean? The rainfall varies, or which periods? ….
Table 2: Precipitation variation …. What is this, the standard deviation from the trend??
262: “With the intensifying human activities and the climate changes, the runoff and the sediment load in the Yangtze River Basin have changed significantly” – this is what you wish to show, no? So do not start with this conclusion …
Fig. 5: The red dotted trend line is misleading, as you wish to emphasize a discontinuity in trend between the two periods. Please omit.
It would be illustrative to present scatter plots between runoff and sediment load for all stations, distinguishing between the natural and impacted periods. Well you did in Fig 6 and 7 for the natural period, but not for the impacted period. I think you should start with these figures, and only then start your statistical analyses.
Table 3: Omit all numbers after decimal point – your data are not accurate enough.
306: Why poor correlation? Not difficult to imagine.
315: Please provide the regression equations, with its coefficients in Table 4.
319: “along the way” which way?
324: Yes, because relations are not linear!!
341: Reconstructed from precipitation data and regression equation, I presume. If so, say this explicitly, don’t let the reader guess what you are doing.
364-366: What a strange way of saying. You want to say: In spite of the climate change induced increase in precipitation, the river runoff decreased, which must be attributed to human interventions.
377: “nevertheless” should read: would have
388: “renewed” What do you mean???
402 (and before): present data on sand mining and explain about soil conservation – estimate its effect
411: does this volume of sediment accumulation in the reservoirs agree with your own analyses? Please elaborate quantitatively.
415-420: I do not understand this para. Above you conclude from your data that runoff has increased – here you say that we cannot ignore water use. Please explain (quantitatively). Fig. 10: how much in comparison to the runoff
434: See comment above. Please compare data with natural flux to put things into perspective.
444: “… in a certain.” ???
446: “since 1954” ???
Section 5.3: Very strange to start with discussion of your statistical analysis, and then present the standard deviation etc. Please re-organize, present all statistical evidence first, and then evaluate.
