Classification and Assessment Methods for Mountain Channel Habitats in the Chishui River Basin, China

Round 1

Reviewer 1 Report

The authors used China’s Chishui River basin as a typical mountain river system. The five chosen parameters are stream order, elevation, slope, sinuosity, and river network density. Additionally, 150 sites were used for habitat classification. The authors recorded 20 metrics in four categories: water environmental status, river morphology, riparian zone, and human disturbance. The presented results identified 40 representative sampling sections belonging to six habitat types that were useful for habitat assessment across the Chishui River basin. The basin was given a mean CHQI score of 130.66 ± 24.14 and classified as “good.” However, headwater, Tongmin River, Tongzi River, and Xishui River were disturbed by various human activities. The process of developing and simplifying our habitat assessment systems could be regarded as a reference for biomonitoring in more mountain river systems. The paper is a good written scientific work, which can be accepted after minor revision. The English should be checked. The contribution of the paper must be an emphasis in more detail. The conclusion section has been omitted. Figure 7 twice times. Both fig 7 and fig 6 must be added grid.

 

Author Response

Response to Reviewer 1 Comments

Point 1: The English should be checked.

Response 1: Thank you for your comment. We have checked the English of this manuscript. We have done the English revisions with the help of Mr. Noah Last (a professional scholar, [email protected]) before the first submission.

Point 2: The contribution of the paper must be an emphasis in more detail.

Response 2: Thank you for your suggestion. We have supplemented part of the discussion and author contributions.

“Similarly, there are a large number mountain channels like the Chishui River in the upper Yangtze River, such as the Han River, the Jinsha River, and the Dadu River [31,32,48]. Characterizing by complex and varied river habitats, they are also hard to research since complicated fluvial geomorphology and inconvenient traffic limit the collection of data and planning needed to customize management activities for unique ecosystems. Therefore, the steps of developing and simplifying our habitat assessment systems presented herein will be helpful for habitats assessment not only in this region but also in other mountain channels with similar characteristics related to human disturbance.”. Line 390-397.

“Author contributions: Jianwei Wang, Fandong Yu and Fei Liu conceived and designed the investigation; Fandong Yu, Fei Liu, Zhijun Xia, Chunsen Xu, and Pengcheng Lin performed field work; Fandong Yu, Zhijun Xia and Jianwei Wang analyzed the data; Miaomiao Hou and Xinhua Zhou contributed materials and analysis tools; Writing—original draft preparation, Fandong Yu and Jianwei Wang; Writing—review and editing, Jianwei Wang and Fandong Yu; project administration, Jianwei Wang and Fei Liu. All authors read and approved the final manuscript. All authors have read and agreed to the published version of the manuscript.” Line 484-489.

Point 3: The conclusion section has been omitted.

Response 3: Thank you for your comment.   We have added a short section (Conclusion) “5. Conclusions

The developing of classification and assessment for mountain channel habitats has been an ongoing issue, convenient and effective methods are needed. To solve the limitations of complicated fluvial geomorphology and inconvenient traffic in mountain channel, a suitable habitat classification scheme based on high resolution satellite imagery was used to simplify the habitat evaluation steps. A total of 40 representative sampling sections belonging to six habitat types that were useful for habitat assessment across the Chishui River basin. Among them, the high-altitude headwater habitat (G2) has the highest proportion (34.17%), while the low-altitude estuary tributaries habitat (G5) had the lowest proportion (2.50%). Data sites 20 and 25–32 with convenient traffic were selected to represent data sites 21–24 with complicated fluvial geomorphology since all data sites from 21 to 32 belonged to group 4: midstream low-curved habitat. The basin was given a mean comprehensive habitat quality index (CHQI) score was 130.66 ± 24.14 and classified under the status “good.” However, headwater, Tongmin River, Tongzi River and Xishui River were disturbed by various human activities. We believe that the process of developing and simplifying our habitat assessment systems presented herein will be helpful for ecosystem assessment not only in this region but also in other mountain channels with similar characteristics related to human disturbance.”. Line 460-477.

Point 4: Figure 7 twice times.

Response 4: Thank you for your comment. We have corrected the latter to "Figure 8". Line 317.

Point 5: Both fig 7 and fig 6 must be added grid.

Response 5: Thank you for your suggestion. We have added grids for figure 6 and figure 7. Line 265, line 291.

Figure 6. Box plot showing the CHQI score of each stream (1: mainstream, 2: Zhaxi River, 3: Daoliu River, 4: Tongche River, 5: Baisha River, 6: Erdao River, 7: Wuma River, 8: Tongzi River, 9: Gulin River, 10: Tongmin River, 11: Datong River, 12: Xishui River).

 

Figure 7. Box plots showing the five classification parameters for each stream (1: mainstream, 2: Zhaxi River, 3: Daoliu River, 4: Tongche River, 5: Baisha River, 6: Erdao River, 7: Wuma River, 8: Tongzi River, 9: Gulin River, 10: Tongmin River, 11: Datong River, 12: Xishui River).

Author Response File: Author Response.docx

Reviewer 2 Report

Review for the paper "Classification and assessment methods for mountain channel habitats in the Chishui River basin, China" by Fandong Yu, Fei Liu, Zhijun Xia, Pengcheng Lin, Chunsen Xu, Jianwei Wang, Miaomiao Hou, Xinhua Zhou submitted to "Water".

 

General comment.

 

Assessment of water quality is one of the most challenging problems arising over the past decades in the era of global climatic changes. Moreover, studying of various aquatic systems needs to be supplemented with comprehensive methods to evaluate possible impacts from human activity. River and streams play an important role in the ecological and economical potential of any area and, therefore, many recent studies were focused on the assessment of their habitats. However, most studies deal with lowland rivers while there are few investigations on the mountain channels. The authors aimed to fill the gap in our knowledge regarding the mountain channels and performed a case study in China. They presented a classification scheme to delineate and simplify the assessment of mountain channel habitats. The authors have demonstrated that six habitat types can be applied to the assessment of habitats in the Chishui River basin where good conditions were observed while other regions, Tongmin River, Tongzi River and Xishui River, were disturbed with human activities. The dataset and methods to process the results are relevant. Statistic treatment is performed in a suitable manner. The main results are presented using relevant Figures and Tables. The discussion is short and focused on the main findings. I have some recommendations to improve the article.

 

Specific remarks.

 

L19. Consider replacing " CHQI " with " comprehensive habitat quality index ".

L23. Consider replacing " more mountain river systems " with " other mountain river systems ".

L60. Consider replacing " now " with " no ".

L74. Consider replacing " reports about " with " reports on ".

L78. Consider replacing " underused " with " less used ".

L89-98. The description of the study area is too short. I recommend providing a general report concerning hydrological and climatic regimes in the region (meteorology, rainfall volume, seasonal fluctuations etc.).

L131. The reference to Table 2 is earlier in the ms than the reference to Table 1 (L168). Please, correct.

L147-149. Please, indicate a measure to estimate the similarity between the studied sites.

Fig. 4. The authors should mark groups in the NMDS plot corresponding to the hierarchical clustering.

L211. Replace (Wang 2018) with p-value.

Fig. 6 caption. Please, explain what do mean vertical bars.

Results. I have not found the results of SIMPER analysis. Please, update the ms with relevant analysis.

L305. Please, correct the reference according to the Journal format.

The authors claimed that one of the aims of the study was to provide a reference guide for similar mountain river systems. Please, provide examples of such systems in other regions and discuss the possible application of the authors' procedure to other habitats.

I suggest including a short section (Conclusion) summarizing the main results.

Author Response

Response to Reviewer 2 Comments

Point 1: L19. Consider replacing " CHQI " with " comprehensive habitat quality index ".

Response 1: Thank you for your comment. We have changed it to “comprehensive habitat quality index (CHOI)” to the manuscript. Line 19.

Point 2: L23. Consider replacing " more mountain river systems " with " other mountain river systems ".

Response 2: Thank you for your comment. We have replaced it with “other mountain river systems” to the manuscript. Line 23.

Point 3: L60. Consider replacing " now " with " no ".

Response 3: Thank you for your suggestion. We have replaced “now few” with “no” to the manuscript. Line 61.

Point 4: L74. Consider replacing " reports about " with " reports on ".

Response 4: Thank you for your suggestion. We have replaced “reports about” with “reports on” to the manuscript. Line 74.

Point 5: L78. Consider replacing " underused " with " less used ".

Response 5: Thank you for your comment. We have replaced “underused” with “underused” to the manuscript. Line 78.

Point 6: L89-98. The description of the study area is too short. I recommend providing a general report concerning hydrological and climatic regimes in the region (meteorology, rainfall volume, seasonal fluctuations etc.).

Response 6: Thank you for your comment. We have added “With a subtropical monsoon climate, the annually average rainfall of the Chishui River was about 1000 mm. The Chishui River contains lots of laterite soil, which could lead to extensive erosion; thus, it is the origin of the name “Chishui” (i.e., “red river” in Chinese). Karst landforms are mainly distributed in the upper and midstream of the river, and the river’s downstream areas belong to the Sichuan Basin [32-34]” to the manuscript. Line 101-105.

Point 7: L131. The reference to Table 2 is earlier in the manuscript than the reference to Table 1 (L168). Please, correct.

Response 7: Thank you for your comment. Table 2 contains some study results and should be placed after Table 1. We therefore canceled reference Table 2 here. Line 139.

Point 8: L147-149. Please, indicate a measure to estimate the similarity between the studied sites.

Response 8: Thank you for your suggestion. We have indicated these measures. “With reference to the previous studies [36,37], five parameters were used: stream order, elevation (m), slope (km/km), sinuosity (km/km) and river network density (km/km2).” Line 138-139.

Point 9: Fig. 4. The authors should mark groups in the NMDS plot corresponding to the hierarchical clustering.

Response 9: Thank you for your suggestion. We have marked groups in the NMDS plot. Line 238.

Point 10: L211. Replace (Wang 2018) with p-value.

Response 10: Thank you for your comment. There are something wrong for “(Wang 2018)”. We have replaced it with reference “[32] Liu, F., Wang, J., Zhang, F.B., Liu, H.Z. Wang, J.W. Spatial organization of fish assemblages in the Chishui River, the last free‐flowing tributary of the upper Yangtze River, China. Ecology of Freshwater Fish. 2020, 30, 1-13.” Line 220.

Point 11: Fig. 6 caption. Please, explain what do mean vertical bars.

Response 11: Thank you for your comment. We have changed “CHQI” to “CHQI scores”. The vertical bars of figure 6 mean CHQI scores. Line 265.

Figure 6. Box plot showing the CHQI score of each stream (1: mainstream, 2: Zhaxi River, 3: Daoliu River, 4: Tongche River, 5: Baisha River, 6: Erdao River, 7: Wuma River, 8: Tongzi River, 9: Gulin River, 10: Tongmin River, 11: Datong River, 12: Xishui River).

Point 12: Results. I have not found the results of SIMPER analysis. Please, update the ms with relevant analysis.

Response 12: Thank you for your comment. We have added Table 3 “Similarity percentages of SIMPER analysis”. Line 244.

Table 3. Similarity percentages of SIMPER analysis

Groups	Average similarity (%)	Groups	Average dissimilarity (%)
Group 1	97.89	Groups 1 & 2	5.39
Group 2	97.13	Groups 1 & 3	7.16
Group 3	98.47	Groups 1 & 4	6.99
Group 4	96.37	Groups 1 & 5	9.69
Group 5	98.77	Groups 1 & 6	10.74
Group 6	97.78	Groups 2 & 3	6.09
		Groups 2 & 4	9.82
		Groups 2 & 5	13.48
		Groups 2 & 6	14.12
		Groups 3 & 4	4.92
		Groups 3 & 5	10.75
		Groups 3 & 6	8.3
		Groups 4 & 5	7.79
		Groups 4 & 6	5.14
		Groups 5 & 6	6.36

Point 13: L305. Please, correct the reference according to the Journal format.

Response 13: Thank you for your comment. We have replaced it with reference “[5] Montgomery, D.R., Buffington, J.M. Channel-reach morphology in mountain drainage basins. Geological Society of America Bulletin. 1997, 109, 596-611”. Line 321.

Point 14: The authors claimed that one of the aims of the study was to provide a reference guide for similar mountain river systems. Please, provide examples of such systems in other regions and discuss the possible application of the authors' procedure to other habitats.

Response 14: Thank you for your comment. We have supplemented part of the discussion: “Similarly, there are a large number mountain channels like the Chishui River in the upper Yangtze River, such as the Han River, the Jinsha River, and the Dadu River [31,32,48]. Characterizing by complex and varied river habitats, they are also hard to research since complicated fluvial geomorphology and inconvenient traffic limit the collection of data and planning needed to customize management activities for unique ecosystems. Therefore, the steps of developing and simplifying our habitat assessment systems presented herein will be helpful for habitats assessment not only in this region but also in other mountain channels with similar characteristics related to human disturbance.”. Line 390-397.

Point 15: I suggest including a short section (Conclusion) summarizing the main results.

Response 15: Thank you for your comment. We have added a short section (Conclusion) “5. Conclusions

The developing of classification and assessment for mountain channel habitats has been an ongoing issue, convenient and effective methods are needed. To solve the limitations of complicated fluvial geomorphology and inconvenient traffic in mountain channel, a suitable habitat classification scheme based on high resolution satellite imagery was used to simplify the habitat evaluation steps. A total of 40 representative sampling sections belonging to six habitat types that were useful for habitat assessment across the Chishui River basin. Among them, the high-altitude headwater habitat (G2) has the highest proportion (34.17%), while the low-altitude estuary tributaries habitat (G5) had the lowest proportion (2.50%). Data sites 20 and 25–32 with convenient traffic were selected to represent data sites 21–24 with complicated fluvial geomorphology since all data sites from 21 to 32 belonged to group 4: midstream low-curved habitat. The basin was given a mean comprehensive habitat quality index (CHQI) score was 130.66 ± 24.14 and classified under the status “good.” However, headwater, Tongmin River, Tongzi River and Xishui River were disturbed by various human activities. We believe that the process of developing and simplifying our habitat assessment systems presented herein will be helpful for habitats assessment not only in this region but also in other mountain channels with similar characteristics related to human disturbance.”. Line 460-477.