Spatiotemporal Variations and Influencing Factors of Arid Inland Runoff in the Shule River Basin, Northwest China

Round 1

Reviewer 1 Report (New Reviewer)

Comments and Suggestions for Authors

The authors utilise a long-term and comprehensive dataset to investigate the dynamics of runoff in the Shule River Basin. The dataset encompasses a period of 65 years (1956-2020) and includes monthly measurements of several hydrological variables from a network of hydrological and meteorological stations.The extensive temporal coverage of the dataset allows for a robust analysis of long-term trends, periodicities, and abrupt changes in runoff. The inclusion of various hydrological variables facilitates a comprehensive understanding of the factors influencing runoff, enabling the authors to explore the relationship between runoff and climatic drivers such as precipitation, temperature, sediment  and evaporation. Although the manuscript boasts a comprehensive dataset spanning 65 years and encompassing various hydrological variables, several sections require clarification and revision for enhanced clarity. Here are specific comments and concerns that require attention from the authors:

1.     The abstract effectively conveys the essence of the study, but it needs some improvement to maximize its impact and clarity. The author should briefly discuss the broader implications of the increasing runoff trends, particularly in the context of water resource management and potential future effects of glacier retreat. For example, the abstract could mention the need to adapt water management strategies to account for these changes, considering the potential for increased water availability in the short term but the long-term threat posed by glacier shrinkage.

2.     To improve conciseness and flow update the abstract by removing redundant phrases and ensuring a smooth, logical flow of information. For instance, the phrase "in order to reveal the relationship between climate and vegetation-runoff response" could be made more concise, and the sentence discussing the multi-time scale periodicity could be rephrased for clarity. In lines 24 and 25 also the contribution rates of precipitation and temperature repeated since they are continuous sentences it is better replacing line 25 by appropriate word. By incorporating these suggestions, the authors can create a more impactful and informative abstract that effectively highlights the study's key findings and their significance for both the scientific community and water resource managers in the Shule River Basin.

3.     Expand on Justification and Significance, while the introduction touches upon the importance of runoff, it needs to investigate deeper into the particular relevance of studying the Shule River Basin. Elaborate on the ecological Integrity, how do runoff changes impact the fragile ecosystem in this arid region? Specify the ecological consequences of altered runoff patterns. Socio-economic Development; Directly link runoff dynamics to the region's socio-economic activities.

4.     Lines 41-56 primarily focus on runoff trends in northern China and modelling techniques. The authors could enhance this section by incorporating studies from a broader geographical context and exploring diverse aspects of runoff dynamics in arid regions. By diversifying the range of sources can craft more comprehensive and insightful introduction that effectively sets the stage for their research on the Shule River Basin.

5.     The abrupt transition in the introduction occurs at line 74, where the manuscript shifts from a general discussion of runoff trends and research methods to a specific focus on the Shule River Basin. This lacks a smooth connection to the preceding paragraphs. The sudden shift may lead to misunderstandings for readers. To improve the flow and clarity of the introduction, the authors should add a transition sentence or connect to broader themes.

6.     While the source mention data collection from 1956 to 2020, Table 1 reveals that certain stations have shorter data series. This discrepancy needs clear explanation. For instance, Panjiazhuang station's data starts in 1959, and Dangchengwan and Danghe Reservoir stations begin in 1966 and 1977, respectively. The authors should address these data gaps and discuss any potential implications for their analysis. Clarify why certain stations have shorter data series. Are these gaps due to equipment malfunction, station establishment dates, or data availability issues? Discuss potential biases, analyze how these gaps might affect the results and conclusions. Do they introduce any limitations to the temporal analysis or the comparability across stations?

7.     How the stations are selected for the analysis of spatiotemporal variations and influencing factors of arid in land runoff in the Basin? For instance, Changmabao, Panjiazhuang, Shuangta Reservoir, Danghe Reservoir, and Dangchengwan stations were selected by long-term runoff data, but what was the criteria reason for the selection of three meteorological stations (Dunhuang, Guazhou, and Yumen) stations?

8.     The authors use a long-time data series from 1956 to 2020, in this long range of data there may be a missed data, how the missed datas were filled and prepared for analysis?

9.     The description of water surface evaporation in Table 1 is somewhat unclear. The authors should clarify whether this refers to actual measurements or estimations derived from pan evaporation data. If pan evaporation is used, the relationship between pan evaporation and actual water surface evaporation should be explicitly stated and any limitations acknowledged.

10.  On lines 171-174, the manuscript mentions several methods for analyzing interannual variation, but their specific application and the rationale behind their selection remains vague. Expanding on the implementation of each method, for example, how the moving average window size was determined or how wavelet analysis was used to assess cyclical characteristics. While the manuscript mentions GIS spatial interpolation, the specific technique employed is not specified. Providing details about the chosen interpolation method (e.g., Kriging, Inverse Distance Weighting) and its parameters would enhance the transparency and reproducibility of the study.

11.  While Figure 7 visually depicts the spatial patterns of runoff, the results section would benefit from more precise quantification including, range which specify the minimum and maximum runoff values observed in each season and annually. This would provide a clearer picture of the spatial variability. Statistical Measures, calculating additional statistical measures such as standard deviation or coefficient of variation to express the spatial heterogeneity of runoff.

12.  Since the discussion acknowledged the influence of glacier melt on runoff but lacks a comprehensive analysis, enhancing this section by quantitative assessment could involve using available data on glacier mass balance or employing hydrological modelling techniques, and discussing the potential future impacts of continued glacier retreat on runoff dynamics in the Shule River Basin. How might these changes affect water availability and management in the long term?

13.  The discussion briefly mentions comparisons with the Heihe River Basin but compare and contrast with other Basins will be providing more insightful context. Draw upon existing research on the Heihe River Basin to inform the discussion on the Shule River Basin. Are there valuable lessons or transferable insights from the Heihe River experience?

14.  While the study recognizes the role of human activities, the discussion could be strengthened by Provide specific examples of human activities impacting runoff in the Shule River Basin, such as dam construction, irrigation practices, and land use changes. How can these findings inform strategies to ensure sustainable water use and ecological integrity in the face of changing runoff patterns?

15.  References should be properly formatted and cited in accordance with the Journal of Water guidelines.

 

16.  Ensure that all references are accurate and consistent in formatting. Some references lack page numbers or volume and issue numbers.

Author Response

The authors utilise a long-term and comprehensive dataset to investigate the dynamics of runoff in the Shule River Basin. The dataset encompasses a period of 65 years (1956-2020) and includes monthly measurements of several hydrological variables from a network of hydrological and meteorological stations.The extensive temporal coverage of the dataset allows for a robust analysis of long-term trends, periodicities, and abrupt changes in runoff. The inclusion of various hydrological variables facilitates a comprehensive understanding of the factors influencing runoff, enabling the authors to explore the relationship between runoff and climatic drivers such as precipitation, temperature, sediment  and evaporation. Although the manuscript boasts a comprehensive dataset spanning 65 years and encompassing various hydrological variables, several sections require clarification and revision for enhanced clarity. Here are specific comments and concerns that require attention from the authors:

Comments 1: The abstract effectively conveys the essence of the study, but it needs some improvement to maximize its impact and clarity. The author should briefly discuss the broader implications of the increasing runoff trends, particularly in the context of water resource management and potential future effects of glacier retreat. For example, the abstract could mention the need to adapt water management strategies to account for these changes, considering the potential for increased water availability in the short term but the long-term threat posed by glacier shrinkage.

Response 1: Line 8~12:Thank you for pointing this out. I agree with this comment. Therefore, With reference to your comments, I have reorganized the background and significance of this study on the increase in runoff from the perspectives of short-term water supply threat and long-term threat posed by glacier shrinkage, as detailed in the abstract of this paper.

Comments 2: To improve conciseness and flow update the abstract by removing redundant phrases and ensuring a smooth, logical flow of information. For instance, the phrase "in order to reveal the relationship between climate and vegetation-runoff response" could be made more concise, and the sentence discussing the multi-time scale periodicity could be rephrased for clarity. In lines 24 and 25 also the contribution rates of precipitation and temperature repeated since they are continuous sentences it is better replacing line 25 by appropriate word. By incorporating these suggestions, the authors can create a more impactful and informative abstract that effectively highlights the study's key findings and their significance for both the scientific community and water resource managers in the Shule River Basin.

Response 2: Line21~22、 26~29:Thank you for pointing this out. I agree with this comment. Therefore, I have removed redundant phrases from the abstract, added the results of the analysis on the periodicity of the time scale, and revised the expression of the sentence in which the contribution rate of precipitation and temperature is placed.

Comments 3: Expand on Justification and Significance, while the introduction touches upon the importance of runoff, it needs to investigate deeper into the particular relevance of studying the Shule River Basin. Elaborate on the ecological Integrity, how do runoff changes impact the fragile ecosystem in this arid region? Specify the ecological consequences of altered runoff patterns. Socio-economic Development; Directly link runoff dynamics to the region's socio-economic activities.

Response 3: Line 47~60:Thank you for pointing this out. I agree with this comment. Therefore, I have expanded the content of the introduction about the importance of studying runoff, and made the following explanations about the correlation between runoff change and watershed particularity, the ecological integrity of the basin, and the role of economic development and runoff change in Shule River basin:

1. Study the particularity and importance of runoff change

The abundance and decline of runoff not only restrict the scale of local social and economic development, but also directly affect the health and stability of the ecosystem. Therefore, in-depth study of the importance of runoff is of great significance for maintaining ecological balance and promoting sustainable development. The Shule River basin is low in the west and high in the east, the upper reaches are in the middle Qilian block, and the north side of the middle and lower reaches are blocked by Ma Mane Mountain, which makes the river flow only westward. This topographic feature not only determines the flow direction of the river, but also affects the distribution and change of runoff. Because the Shule River Basin belongs to an arid climate area, runoff becomes a key factor to maintain the health of the ecosystem under this climate condition. The runoff of rivers directly determines the scope and scale of oasis and desert vegetation. The geological and soil conditions of Shule River Basin also affect the change of runoff. For example, the upstream area has extensive glaciers and good vegetation, which are conducive to the formation and maintenance of runoff. In the middle and lower reaches, the runoff may be reduced due to strong soil permeability.

2. Impacts of ecological integrity and runoff changes

When river runoff is reduced, water quality is susceptible to pollution. Due to the lack of enough water to wash, pollutants are easy to stay in the water, leading to the deterioration of water quality. At the same time, reduced runoff can also lead to insufficient supplies of dissolved oxygen in the water body, posing a threat to the survival of fish and other aquatic life. Changes in runoff may lead to changes in habitat. For example, when runoff decreases, wetlands and floodplains can dry up, causing the birds and animals that inhabit these places to lose their habitat. On the other hand, increased river runoff can also lead to flooding and damage the biological habitat of riverbanks and surrounding areas. The variation of runoff directly affects the suspension and sedimentation process of sediments. When the river runoff increases, the transport capacity of suspended matter and sediment will be enhanced, which will accelerate the erosion and erosion process of the river, resulting in the change of the river morphology. These changes further affect the sustainability and stability of biological habitats.

3. Ecological consequences of changing runoff patterns

With the continuous development of climate change and human activities, the runoff pattern of Shule River basin is changing. This change has a profound impact on the ecosystem, including: (1) Ecosystem degradation: Prolonged drought and reduced runoff lead to ecosystem degradation, decreased vegetation cover, increased soil erosion, and reduced biodiversity. (2)Water scarcity: Changes in runoff patterns have exacerbated water scarcity, which has had a serious impact on agricultural irrigation, industrial water use, and residential water use. (3) Frequent natural disasters: Increased runoff may cause natural disasters such as floods, posing a threat to people's lives and property safety. At the same time, the frequent occurrence of droughts and floods also increases the vulnerability of the ecosystem.

4. Relationship between socio-economic development and runoff dynamics

(1) Agriculture is an important economic pillar in Shule River Basin. The abundance and decline of runoff directly affect the water supply of agricultural irrigation. In dry years, reduced runoff can lead to insufficient irrigation water sources, affecting crop yields and quality. (2) With the acceleration of industrialization, the demand for industrial water is increasing. Runoff stability and reliability have become important factors affecting industrial development. Reduced runoff may lead to industrial water shortages, affecting the normal operation of industrial production. (3) Residential water consumption is an important manifestation of runoff dynamics. In drought years, the decrease of runoff may lead to domestic water stress and affect the normal life of residents.

Comments 4: Lines 41-56 primarily focus on runoff trends in northern China and modelling techniques. The authors could enhance this section by incorporating studies from a broader geographical context and exploring diverse aspects of runoff dynamics in arid regions. By diversifying the range of sources can craft more comprehensive and insightful introduction that effectively sets the stage for their research on the Shule River Basin.

Response 4:

Line 65~90: Thank you very much for your valuable comments and suggestions in this section, in response to your suggestions, we will make the following changes: By searching and integrating relevant studies from different geographical areas, we found the diversity of the study area for the distribution of runoff studies in geographical, climatic and hydrological characteristics. For example, China is concerned about the sources of the Yangtze River, Yellow River, Lancang River, Nu River and other major rivers, the arid northwest region, the southeastern coastal region, inland lakes and river basins, while foreign countries are concerned about the Mississippi River basin, Colorado River basin, Rhine River, Danube river and other major river basins, Ganges River basin and Indus River basin. The current research status of runoff evolution models in arid areas is summarized to cover a wider geographical background.

Comments 5: The abrupt transition in the introduction occurs at line 74, where the manuscript shifts from a general discussion of runoff trends and research methods to a specific focus on the Shule River Basin. This lacks a smooth connection to the preceding paragraphs. The sudden shift may lead to misunderstandings for readers. To improve the flow and clarity of the introduction, the authors should add a transition sentence or connect to broader themes.

Response 5: Line 105~108:Thank you for pointing this out. I agree with this comment. Therefore, I have added transitional sentences to explain the significance of studying runoff change in the arid area of Shule River Basin.

Comments 6: While the source mention data collection from 1956 to 2020, Table 1 reveals that certain stations have shorter data series. This discrepancy needs clear explanation. For instance, Panjiazhuang station's data starts in 1959, and Dangchengwan and Danghe Reservoir stations begin in 1966 and 1977, respectively. The authors should address these data gaps and discuss any potential implications for their analysis. Clarify why certain stations have shorter data series. Are these gaps due to equipment malfunction, station establishment dates, or data availability issues? Discuss potential biases, analyze how these gaps might affect the results and conclusions. Do they introduce any limitations to the temporal analysis or the comparability across stations?

Response 6: Line 202~204: Thank the reviewers for their attention to the difference in data series length and their valuable comments. We have explained these problems in the paper. As pointed out by reviewers, the data of Panjiazhuang Station began in 1959, while that of Dangchengwan Station and Danghe Reservoir Station began in 1966 and 1977 respectively. These sites were established relatively late, so their data series are shorter. However, all the data passed the three characteristics test (reliability, consistency, representativeness), so it can be used for hydrological analysis, and has little impact on the overall research effect of Shule River.

Comments 7: How the stations are selected for the analysis of spatiotemporal variations and influencing factors of arid in land runoff in the Basin? For instance, Changmabao, Panjiazhuang, Shuangta Reservoir, Danghe Reservoir, and Dangchengwan stations were selected by long-term runoff data, but what was the criteria reason for the selection of three meteorological stations (Dunhuang, Guazhou, and Yumen) stations?

Response 7: Thank you for your comments. I will explain the selection of Yumen Station, Guazhou Station and Dunhuang Station as observation points for the study of Shule River Basin meteorology:

1. Geographical representation

Yumen Station: Located in the upper reaches of the Shule River Basin, it can reflect the meteorological characteristics of the upper reaches of the basin.

Guazhou Station: located in the middle and lower reaches, it complements Yumen Station to form a comprehensive monitoring of meteorological characteristics in the middle and lower reaches.

Dunhuang Station: Located in the western edge of Shule River basin, located in the Gobi Desert, its meteorological characteristics have a unique representative, can reflect the extreme dry climate conditions in the basin meteorological changes.

2. Typicality of climate characteristics

The climate characteristics of the regions where these three observation points are located are different, but they are all typical. The middle and upper reaches of Yumen and Guazhou stations are relatively wet (compared to Dunhuang), while Dunhuang Station represents an extremely dry climate.

Because of its extremely dry climate, Dunhuang Station has become an ideal place to study land-air interaction and its influence on climate variation. The underlying surface of Dunhuang Gobi has strong solar radiation in spring and summer, strong sensible heat transport, and deep boundary layer characteristics, which are of great significance for the study of climate change.

3. Continuity and integrity of observation data

All three observation points have long-term continuous meteorological data. In particular, the Dunhuang Station has carried out comprehensive stereoscopic observation experiments on land-air interaction in the extremely arid Dunhuang area since 2000, and has accumulated many years of continuous observation data. These continuous and complete meteorological observation data provide valuable basic data for the study of the law of climate change and its impact on hydrology and water resources in Shule River Basin.

Comments 8: The authors use a long-time data series from 1956 to 2020, in this long range of data there may be a missed data, how the missed datas were filled and prepared for analysis?

Response 8: Thank you for your opinion. In the case of data missing in the study, we generally refer to the data of nearby hydrologic stations and use the multiple linear interpolation method for interpolation.

Comments 9: The description of water surface evaporation in Table 1 is somewhat unclear. The authors should clarify whether this refers to actual measurements or estimations derived from pan evaporation data. If pan evaporation is used, the relationship between pan evaporation and actual water surface evaporation should be explicitly stated and any limitations acknowledged.

Response 9: Line 198~199: Thank you for your comments, which have been supplemented in article 2.2.1 to explain that evaporation from water surface is measured using E601 evaporation dish.

Comments 10: On lines 171-174, the manuscript mentions several methods for analyzing interannual variation, but their specific application and the rationale behind their selection remains vague. Expanding on the implementation of each method, for example, how the moving average window size was determined or how wavelet analysis was used to assess cyclical characteristics. While the manuscript mentions GIS spatial interpolation, the specific technique employed is not specified. Providing details about the chosen interpolation method (e.g., Kriging, Inverse Distance Weighting) and its parameters would enhance the transparency and reproducibility of the study.

Response 10:

Line 217~226、231~245、251~256:Thank you for pointing this out. I agree with this comment. Therefore, I have added MK mutation test, R/S analysis method, 5-year moving average and the analysis and calculation principle of wavelet analysis in 2.2.2 of the paper, and explained that the Kriging interpolation is used for spatial analysis of GIS interpolation in the paper, and added specific operation steps.

Comments 11: While Figure 7 visually depicts the spatial patterns of runoff, the results section would benefit from more precise quantification including, range which specify the minimum and maximum runoff values observed in each season and annually. This would provide a clearer picture of the spatial variability. Statistical Measures, calculating additional statistical measures such as standard deviation or coefficient of variation to express the spatial heterogeneity of runoff.

Response 11: Line 372~380:Thank you for pointing this out. I agree with this comment. Therefore, according to your suggestions, I have added the annual and seasonal runoff variation coefficients of each station to represent the spatial heterogeneity changes.

Comments 12: Since the discussion acknowledged the influence of glacier melt on runoff but lacks a comprehensive analysis, enhancing this section by quantitative assessment could involve using available data on glacier mass balance or employing hydrological modelling techniques, and discussing the potential future impacts of continued glacier retreat on runoff dynamics in the Shule River Basin. How might these changes affect water availability and management in the long term?

Response 12: Line 484~532、569~570:Thank you for pointing this out. I agree with this comment. Therefore, I have comprehensively compared and evaluated the models (hydrological model simulation, glacier mass balance measurement, isotope analysis, scenario prediction) for the impact of glacier ablation on runoff change. Due to the limited data acquisition defects in the study area, this paper selects temperature-runoff response function to determine the impact degree, and analyzes the correlation changes between temperature and runoff in the study area from the perspectives of annual and interannual. Then the time and influence of abrupt glacier ablation were determined. Potential future impacts and countermeasures were discussed.

Comments 13: The discussion briefly mentions comparisons with the Heihe River Basin but compare and contrast with other Basins will be providing more insightful context. Draw upon existing research on the Heihe River Basin to inform the discussion on the Shule River Basin. Are there valuable lessons or transferable insights from the Heihe River experience?

Response 13: Line 533~54、551~561:Thank you for pointing this out. I agree with this comment. Therefore, I have sorted out relevant data and learned that Shule River, Heihe River, Shiyang River and Harten River are all located in arid and semi-arid regions in northwest China, facing the challenges brought by rising temperatures and changing precipitation patterns. The trend of glacier loss in these basins is similar, with initial runoff increasing but decreasing in the long term. This conclusion has been added to the discussion section of the paper to provide a more insightful background for the discussion. For the problems of Shule River water resources management, we can refer to the implementation of IWRM framework in Heihe River Basin to improve the integrated water resources management capacity. Advanced agricultural water-saving technologies and management models in arid areas such as Israel and Australia can also be investigated to improve agricultural water efficiency.

Comments 14: While the study recognizes the role of human activities, the discussion could be strengthened by Provide specific examples of human activities impacting runoff in the Shule River Basin, such as dam construction, irrigation practices, and land use changes. How can these findings inform strategies to ensure sustainable water use and ecological integrity in the face of changing runoff patterns?

Response 14: Lines 468~481: Thanks for pointing this out. I agree with this comment. Therefore, I have added the main human activities that affect changes in runoff, as well as strategies to ensure sustainability.

Comment 15: References should be properly formatted and cited according to Journal of Water guidelines.

Reply 15: Line 633: Thanks for pointing this out. I changed it

Note 16: Make sure all references are correct and formatted consistently. Some references do not have page numbers or volume and edition numbers.

Reply 16: Line 633: Thanks for pointing this out. I changed it

Reviewer 2 Report (New Reviewer)

Comments and Suggestions for Authors

This study analyzed the correlation between key hydrological factors—precipitation, temperature, sediment, and evaporation—and runoff during the 40 years period 1980-2020, highlighting their critical role in regulating runoff.  The study employed various statistical methods, including the Mann-Kendall (M-K) test, wavelet analysis, RS analysis, and spatial interpolation, to comprehensively examine the spatial and temporal evolution of runoff on annual and inter-annual scales. The paper was easy to read and scientifically sound. my recommendation is to accept the paper with minor comments.

In abstract please state the number of runoff stations used before saying changmabao station (line 15). The study has used 5 stations.

Line 16- how many reservoirs were studied

What is the vegetation forest cover area percentage of studied basin? State in abstract please as the relationship between climate and vegetation-runoff response is understudied.

In the section 2.1 what is the total catchment area of the studied basin? Also, how much the catchment area is covered by vegetation forest? What are the soil characteristics in different regions of basin (southern western and eastern)? Line 124-127 stating only Qilian area mountains vegetation is high and in middle reaches vegetation is scarce does not explain the vegetation coverage.

Kindly put flow direction arrow in fig 1 b south east to north west

In fig 4e  Danghe reservoir at the upstream of the studied basin, there is peak runoff volume upto the value of 8 at 2013-2019 section not impacting much to the downstream stations and is not well represented by the five year sliding average flow. Please comment on it.

In discussion- although the impact of evapotranspiration in the studied catchment is not significant as stated in the results (line 350-356) but could also become important in future due to rising temperatures in the high vegetation zones kindly comment on it in discussion.

In conclusion : Changmabao station and Shuangtabao reservoir (line 415) please state their locations upstream downstream or at the centre of the catchment 

Author Response

This study analyzed the correlation between key hydrological factors—precipitation, temperature, sediment, and evaporation—and runoff during the 40 years period 1980-2020, highlighting their critical role in regulating runoff.  The study employed various statistical methods, including the Mann-Kendall (M-K) test, wavelet analysis, RS analysis, and spatial interpolation, to comprehensively examine the spatial and temporal evolution of runoff on annual and inter-annual scales. The paper was easy to read and scientifically sound. my recommendation is to accept the paper with minor comments.

Comments 1:In abstract please state the number of runoff stations used before saying changmabao station (line 15). The study has used 5 stations.

Line 16- how many reservoirs were studied

Response 1: Line15~19:Thank you for pointing this out. I agree with this comment. Therefore, I have added the number of hydrographic stations in the summary.

Comments 2:What is the vegetation forest cover area percentage of studied basin? State in abstract please as the relationship between climate and vegetation-runoff response is understudied. In the section 2.1 what is the total catchment area of the studied basin? Also, how much the catchment area is covered by vegetation forest? What are the soil characteristics in different regions of basin (southern western and eastern)? Line 124-127 stating only Qilian area mountains vegetation is high and in middle reaches vegetation is scarce does not explain the vegetation coverage.

Response 2: Line 147~151、155~180:Thank you for pointing this out. I agree with this comment. Therefore, I have added in section 2.1 the area of the watershed catchment, as well as the specific vegetation coverage and soil characteristics. At the same time, it is explained that climate change will affect the growth and distribution of vegetation, and then affect the process of runoff recharge and consumption. At the same time, changes in vegetation also have an impact on climate and runof.

Comments 3: Kindly put flow direction arrow in fig 1 b south east to north west

Response 3: Line191~192:Thank you for pointing this out. I agree with this comment. Therefore, I have added the flow direction arrows on Figure 1b. For details, please refer to Figure 1.

Comments 4: In fig 4e  Danghe reservoir at the upstream of the studied basin, there is peak runoff volume upto the value of 8 at 2013-2019 section not impacting much to the downstream stations and is not well represented by the five year sliding average flow. Please comment on it.

Response 4: Thank you for your valuable advice. I will explain as follows: The reason for the sudden increase of runoff in Danghe Reservoir in 2017 is as follows: Studies show that the average annual temperature in Dunhuang area has shown a rising trend from 1955 to 2015, and there has been a significant change around 1997. Rising temperatures have accelerated the melting of glaciers and snow in the upper Qilian Mountains, especially during the summer months, when more meltwater flows into river systems. Moreover, in 2016, the annual precipitation of Danghe Reservoir Station suddenly increased to 108.7mm, resulting in a sudden increase in runoff in this area in 2017. However, these extreme weather events have a significant impact on runoff in the current year, but they do not necessarily predict long-term trends.

The 5-year moving average is designed to smooth out short-term fluctuations in the data series and reveal more stable long-term trends. It eliminates random year-to-year variations by calculating average runoff over five consecutive years, allowing us to better identify potential trend changes. If the amount of runoff in a given year is much higher than in other years, it has a relatively small weight in the five-year moving average and does not have a large impact on the overall trend. Thus, a single one-year spike is not enough to change the average over the entire five-year period.

Comments 5: In discussion- although the impact of evapotranspiration in the studied catchment is not significant as stated in the results (line 350-356) but could also become important in future due to rising temperatures in the high vegetation zones kindly comment on it in discussion.

Response 5: Line 438~447:Thank you for pointing this out. I agree with this comment. Therefore, I added the effect of evapotranspiration on runoff in the Shule River basin. The current study shows that the evapotranspiration in the Shule River basin is relatively low and has limited influence on the change of runoff. This may be due to the region's dry climate, low vegetation cover and good water management practices. However, existing studies are often based on historical data and short-term observations, and may not adequately capture potential trends in evapotranspiration under long-term climate change. As global warming intensifies, the effects are likely to be felt gradually.

According to climate change models published by the IPCC and other bodies, several regions in northwest China, including the Shule River basin, will continue to experience rising temperatures in the coming decades, and the frequency of extreme weather events is likely to increase. Under the combined action of these factors, evapotranspiration in the high vegetation zone is likely to become more active. With the increase of temperature, the ecosystem structure and function of the high vegetation zone may change, such as the change of vegetation type and the decrease of biodiversity, etc., and these changes will affect the intensity and pattern of evapotranspiration. For example, drought-tolerant plants may gradually replace the original vegetation, resulting in a decrease in the overall evapotranspiration efficiency. Conversely, if vegetation growth conditions improve, more evapotranspiration may be promoted.

In the face of changing climatic conditions, water managers need to re-examine the role of evapotranspiration in the overall hydrological cycle, especially in high vegetation zones. The monitoring and research of evapotranspiration should be strengthened, and more accurate prediction model should be established to provide basis for the formulation of scientific and rational water resources management strategies. With the increase of evapotranspiration, it is necessary to dynamically adjust the water resources allocation scheme in the basin to ensure that the key ecological areas can obtain enough ecological water demand and maintain the health and stability of the ecosystem.

Comments 6: In conclusion : Changmabao station and Shuangtabao reservoir (line 415) please state their locations upstream downstream or at the centre of the catchment

Response 6: Line581~582:Thank you for pointing this out. I agree with this comment. Therefore, I have explained in the article.

Round 2

Reviewer 1 Report (New Reviewer)

Comments and Suggestions for Authors

The author has revised most of the review comments, and the content is in line with my expectations, but if the conclusion can in-depth discussions to explain the results., it will make this article more interesting.

Author Response

Comments and Suggestions for Authors：The author has revised most of the review comments, and the content is in line with my expectations, but if the conclusion can in-depth discussions to explain the results., it will make this article more interesting.

Respond：Thank you for raising this point and I agree with you. Therefore, I have discussed the conclusion in depth, resorted out the reasons for the study results, and added the measures that need to be carried out to cope with the future melting of glaciers.

Author Response File: Author Response.pdf

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

This paper deals with a detailed hydrological analysis of the Shule River basin in north-west China. We are dealing with a basin defined as a high mountain basin. It is also characterised by aridity resulting from orography. The authors have used a very wide range of statistical analysis and other methodologies to identify temporal trends.

The reviewer has many comments on the paper, too many to elaborate on. Therefore, only general guidelines are given below.

It is clear from the paper that a large and very systematic amount of work has been done, involving a very wide range of data, as well as a very wide range of methods. Nevertheless, the reviewer considers that the paper is not adequately written. First of all, there is a question of methodological correctness. The methods used by the authors are very numerous, some of them widely established and routine, and some of them not so. Appropriate references should be given for all the methods used by the authors. Descriptions of methods that are not defined in the Methodology section appear throughout the text, in the Results and in the Discussion. Some hydrological variables are introduced in the initial section and then new variables (e.g. sediment) appear in the Results that were not previously considered. With such a wide range of methods, it would also be useful to define which are more useful and which are not.

The article makes a lot of general claims, which are plausible and reasonable, but are not adequately supported by the results.

The plethora of methods used makes the paper very unsystematic. The paper also gives a very large number of results, which are not presented in the clear way. It is not useful to list numerical data in the text, and many of the results would have been better presented in tables. This would make the text much clearer.

It seems that each group of authors wrote each part of their text independently, and then the text was not unified and harmonised throughout the article. As a result, some parts of the text are repetitive (e.g. information on meteorological and hydrological stations) and some descriptions are not harmonised. 

The article needs to be thoroughly reworked for publication and, above all, the text needs to be written in a more systematic way. Only the relevant parts of the text should be included in the Methodology, Results and Discussion sections. In the text of the article, however, all this is mixed up. 

As the article will be published in an international journal, the objectives should also be better defined. Why data processing for this catchment area is meaningful and relevant. The presentation of topography and geography also needs to be improved. All topographic names should be shown in appropriate figures.

Comments on the Quality of English Language

Comments in Comments and Suggestions for Authors.

Reviewer 2 Report

Comments and Suggestions for Authors

The manuscript „Spatiotemporal variations and influencing factors of arid inland runoff in the Shule River Basin, Northwest China” summarizes the research results on the Shule River runoff changes. The Authors presented and achieved three research objectives:

(1) to determine the inter-annual and intra-annual variations of runoff by using methods such as linear regression, moving average, cumulative anomaly, and concentration degree;

(2) to reveal the temporal and spatial evolution rules of runoff throughout the year and four seasons using MK test, wavelet analysis, RS analysis, and spatial interpolation as qualitative analytical methods;

(3) to explore the correlation between hydrological factors and runoff changes in the benchmark and variation periods through Pearson correlation coefficient and cumulative slope comparison methods;

Moreover, The Authors explored additional subject which has not been mentioned among the goals, i.e.:

4) Grey prediction model, autoregressive integrated moving average (ARIMA) model, BP neural network and support vector machine (SVM) model were used to analyze the future annual runoff evolution trend.

The main stream of Shule River has a total length of 670 km and a basin area of ​​413,000 km2. The catchment area exhibits temperate continental arid climate characteristics. The given average annual precipitation values ​​of 70 mm and evaporation of 2400-3200 mm raise my doubts as to whether there is still runoff in such conditions - the climate suggests more desert conditions than temperate ones.

The presented research results are correct in terms of content and the used methods are appropriate. I assume that the given average annual precipitation amount is incorrect and will be corrected in the final version of the manuscript text.

The text is organized correctly, although the "discussion" chapter presents the research results from the assumed objective no. 3 and it is difficult to treat it as a discussion. I suggest modifying the chapter title.

What should be appreciated is that the manuscript contains formulated conclusions, few authors follow these formal rules nowadays.

Reviewer 3 Report

Comments and Suggestions for Authors

Comments and suggestions are in the attached file

Comments for author File: Comments.pdf