Ecological Risks Arising in the Regional Water Resources in Inner Mongolia Due to a Large-Scale Afforestation Project

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

The manuscript evaluated the ecological risk of water resources caused by afforestation in Inner Mongolia, China. Based on land cover data, Normalized Difference Vegetation Index (NDVI) data, and meteorological data, ths study used trend analysis, water balance equation, and Water resources Security Index (WSI) index to analyze the ecological risks of water resources caused by afforestation in Inner Mongolia from 2000 to 2020.

1.     Line 216, is there an increase of irrigation water consumption in Inner Mongolia? How to deal with it in the water balance of each region?

Comments on the Quality of English Language

1.     Line 20, used -> we used.

2.     Line 118, datasets -> dataset

3.     Line 157, as afforestation area -> as an afforestation area

4.     Line 185, vegetation -> and vegetation

5.     Line 186, part -> parts

6.     Line 210, increasing -> an increase

7.     Line 242, ~bout -> ~

Author Response

According to the reviewer’s comments, we have revised the manuscript extensively. If there are any other modifications we could make, we would like very much to modify them and we appreciate your help. We hope that our manuscript can be considered for publication. Thank you very much for your help. Revised portions are marked in red in the "track changes". Point-by-point responses to the reviewer are listed below this letter.

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

Large-scale afforestation projects and related ecological risks is undoubtedly very interesting topic which has been poorly investigated so far. However, from the beginning, the authors approach the issue of the impact of afforestation on the water regime with a very simple lens, which in itself gives an idea of the result. The authors came to the conclusion that “Large-scale afforestation increases total water consumption, leading to regional water resource consumption and becoming a potential source of ecological risks in the region.” Although I do not know the local conditions, in general I have to disagree with the authors. On the contrary, forests affect the hydrological cycle in a positive way helping to retain the precipitation at the point of fall and recharge the groundwater levels. Large-scale forested areas can have a considerable effect on local water regime in this sense.

 

The whole problem of hydrological cycle and water balance is substantially simplified in the manuscript. Substantial variables of basin water resource change, including surface runoff, (vegetation) interception, or infiltration were absolutely neglected. Therefore, I consider the equation (5) and subsequently, also equation (6) incomplete. In the Method and Results sections there was no reference about groundwater supplies, which are crucial in the whole hydrological cycle.

From the above reasons, I have to insist that presented data are misinterpreted.

The discussion part is not well connected to previous parts and doesn’t put own results into context with the literature results. Unlike previous Method and Results sections, it mainly deals with groundwater, thus making the results less clear.

Lines 41 – 43: “It was confirmed that forests could increase regional evapotranspiration and reduce total runoff discharge compared to the absence of forests under the same precipitation conditions.” It is unclear whether the authors consider these phenomena positive or negative. Please, explain.

Lines 44 – 45: “Some studies pointed out that 10-40% of annual precipitation was lost by the canopy interception [8].” Please, explain what you mean by the expression “lost”. From my point of view, the interception is positive impact of the vegetation - helping to retain the precipitation at the point of fall.

Lines 47 – 48: “Moreover, in forests, the shallow roots extract soil water provided by precipitation while consuming groundwater by the deep roots during the dry period.” Again, do you consider these phenomena positive or negative? Please, explain.

Lines 157 – 158: “Finally, the extraction results were verified by using 23 afforestation sample points obtained from field investigation in Ulanqab. The overall identification accuracy was 73.9%.” Please, specify the way how verifications was performed and how the accuracy rate was calculated.

Lines 169 -170: I cannot agree with the sentence: “Δ? indicates to basin water resource change (mm), which is generally assumed to be zero in a long term.”

 

I only must agree with the authors, that “Inner Mongolia is a perfect natural laboratory to study the forest’s effects on regional water resources.” Therefore, it would be irresponsible to make incorrect conclusions, even if they are based on real data.

Comments on the Quality of English Language

English language is fine. I have only identified few places with not quite clear meaning.

Author Response

According to the reviewer’s comments, we have revised the manuscript extensively. If there are any other modifications we could make, we would like very much to modify them and we appreciate your help. We hope that our manuscript can be considered for publication. Thank you very much for your help. Revised portions are marked in red in the "track changes". Point-by-point responses to the reviewer are listed below this letter.

Author Response File: Author Response.pdf

Reviewer 3 Report

Comments and Suggestions for Authors

The paper introduces a compelling concept related to the risks associated with water resource demand in the context of afforestation. It effectively demonstrates that ongoing afforestation in the study area can lead to significant alterations in the water balance.

Regarding Figure 1, it might be beneficial to reconsider the title, and I suggest including "land use" in the title for better clarity.

Expanding both the spatial and quantitative aspects of the afforestation sample points, which currently comprise only 23 points from a single region, would enhance the robustness of the study.

Line 123 and the associated maps require clarification regarding the data format. It appears that land use and NDVI data are in raster format, while water resources are presented as points. It's important to explain why different data formats are used.

Figure 8 appears two times please address this redundancy.

In Figures 8 and 9, it's crucial to provide an explanation of how the graphs were computed. Specifically, clarify if spatial areal averaging was applied to the afforestation regions, shown in Figure 5.

Line 193 mentions "km2/a"; it would be clearer to specify whether this refers to "km2/year" or "km2/area" to avoid any ambiguity.

Author Response

According to the reviewer’s comments, we have revised the manuscript extensively. If there are any other modifications we could make, we would like very much to modify them and we appreciate your help. We hope that our manuscript can be considered for publication. Thank you very much for your help. Revised portions are marked in red in the "track changes". Point-by-point responses to the reviewer are listed below this letter.

Author Response File: Author Response.pdf

Reviewer 4 Report

Comments and Suggestions for Authors

The topic of research is very attractive and practical because one of the concerns of large projects is their effects on ecology, especially water resources. But about this article I have a big concern about its novelty. Under these conditions, this article cannot be more than a technical report. Unless a special innovation is included in it. My other comments are as follows:

1-     Research questions and objectives should be explained more clearly in the end of the introduction.

2-     The unit of water resources in the form of MCM or 1000MCM is widely used and more understandable.

3-     In the caption of Figure 1, more descriptions of the maps are required. Maps should be named (such as A and B) and explained in the caption.

4-     What does “a” mean on the x-axis in Figure 8? Also Figure 9.

5-     In Figure 7, filled icons (to change water sources) cause the information to not be displayed well. Please use the no fill icon. It may be the same for Figure 8 (on line 252). In addition, it is referred twice with number 8 to the figures.

6-     Equation 6 should be rewritten.

7-     The conclusion needs to be developed.

Good luck

Author Response

According to the reviewer’s comments, we have revised the manuscript extensively. If there are any other modifications we could make, we would like very much to modify them and we appreciate your help. We hope that our manuscript can be considered for publication. Thank you very much for your help. Revised portions are marked in red in the "track changes". Point-by-point responses to the reviewer are listed below this letter.

Author Response File: Author Response.pdf

Round 2

Reviewer 4 Report

Comments and Suggestions for Authors

The manuscript now appears to be suitable for publication.