Thermal Regime Characteristics of Alpine Springs in the Marginal Periglacial Environment of the Southern Carpathians

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

Sustainability-3587422

Thermal regime characteristics of alpine springs in the marginal periglacial environment of southern Carpathians

The submitted manuscript addresses an interesting topic; it is well-written and its content is clearly presented. In my opinion, it could be published in Sustainability.

However, there are minor details that need to be corrected or expanded:

1. 45-47, the problem of acid rock drainage resulting from melting permafrost in mountainous areas and its effects on the water quality and aquatic ecosystems should also be noted.
2. 202, there are four springs (RS1, RS33, RS18 and RS25), not three.
3. 210, 228 and 277, try not to start the sentence with “Figure x”.

Author Response

Dear Reviewer,

We sincerely appreciate your careful review and valuable feedback on our manuscript. Your insightful comments have played a crucial role in enhancing the clarity and quality of our study. We have thoughtfully considered all your suggestions and have incorporated the necessary revisions into the updated manuscript.

Below, we provide detailed explanations of the changes made in response to each of your comments, with line references corresponding to the version with accepted modifications. We hope our revisions effectively address your concerns and further strengthen the manuscript.

Thank you once again for your time and thoughtful review.

Comment 1:

Thermal regime characteristics of alpine springs in the marginal periglacial environment of southern Carpathians

The submitted manuscript addresses an interesting topic; it is well-written and its content is clearly presented. In my opinion, it could be published in Sustainability.

However, there are minor details that need to be corrected or expanded:

1. 45-47, the problem of acid rock drainage resulting from melting permafrost in mountainous areas and its effects on the water quality and aquatic ecosystems should also be noted.

Response 1:

We added the following phrase in the Introduction: `Additionally, the thawing of permafrost in mountainous regions may also trigger acid rock drainage, with potentially harmful consequences for water quality and aquatic ecosystems [11]`.

 

Comment 2:

2. 202, there are four springs (RS1, RS33, RS18 and RS25), not three.

Response 2:

Thank you for the observation, we changed `three` to `four`.

 

Comment 3:

210, 228 and 277, try not to start the sentence with “Figure x”.

Response 3:

We rephrased all these sentences and now no one starts with `Figure`.

`Spring temperatures measured during summer 2021 using a portable digital thermometer are shown in Figure 4a`.

`Continuous temperature measurements from data loggers monitoring three springs emerging from rock glaciers recorded during the warm seasons between late June 2021 and September 2023 are illustrated in Figure 5a`.

`Temperature variations of six springs, measured at varying distances downslope from the rock glacier fronts are depicted in Figure 8.`

Reviewer 2 Report

Comments and Suggestions for Authors

The manuscript tried to determine the how residual ice in debris glaciers affects the temperature of spring water flowing in the high mountain area of the Romanian Southern Carpathians. Comparisons were made with the teperature of water from springs flowing from other locations such as scree slopes and talus slopes, meadow-covered slopes, and cirque/valley floors. The authors prove that there is a relationship between water temeratures and water of springs flowing from debris glaciers and other sites. They suggest that water flowing from debris glaciers is cooler than water flowing from other locations. They attempt to prove this on a small number of measurements and do not provide more information on the atmospheric conditions prevailing at the time of the measurements.  In the context of the importance of this research, some information on the physico-chemical state of the water, simple measurements like pH or conductivity, would be useful. Nevertheless, I think that the article „ Thermal Regime Characteristics of Alpine Springs in the Mar-2 ginal Periglacial Environment of the Southern Carpathians” will be of interest to readers of the journal Sustainability. I have indicated my additional comments and queries in the text of the manuscript.

Comments for author File: Comments.pdf

Author Response

Dear Reviewer,

Thank you very much for kind review.

 

Comment 1:

The manuscript tried to determine the how residual ice in debris glaciers affects the temperature of spring water flowing in the high mountain area of the Romanian Southern Carpathians. Comparisons were made with the teperature of water from springs flowing from other locations such as scree slopes and talus slopes, meadow-covered slopes, and cirque/valley floors. The authors prove that there is a relationship between water temeratures and water of springs flowing from debris glaciers and other sites. They suggest that water flowing from debris glaciers is cooler than water flowing from other locations. They attempt to prove this on a small number of measurements and do not provide more information on the atmospheric conditions prevailing at the time of the measurements.  In the context of the importance of this research, some information on the physico-chemical state of the water, simple measurements like pH or conductivity, would be useful. Nevertheless, I think that the article „ Thermal Regime Characteristics of Alpine Springs in the Mar-2 ginal Periglacial Environment of the Southern Carpathians” will be of interest to readers of the journal Sustainability. I have indicated my additional comments and queries in the text of the manuscript.

Response 1:

Thank you for this general comment.

 

Comment 2:

Page 4 - Figure 1: what is the contour line?

Response 2:

It is a line connecting points of equal elevation (isohypse). We have corrected the elevation values.

 

Comment 3:

Page 5 - Figure 3: It is unfortunate that not all of the springs tested had the same temperature measurement interval. The data is not complete

Response 3:

Thank you for your comment. You are correct that the measurement interval differs between locations, as sampling in high mountain environments presents significant challenges. However, as clearly shown in Figure 6, there were only minor variations in spring water temperatures during the 2020-2023 monitoring period. Our findings suggest that spring water temperatures in the study area are relatively stable, especially if they emerge from ground ice. Furthermore, temperature data from data-loggers show relatively stable thermal regimes across the monitoring sites (see Fig 5a). While we agree that long-term monitoring is essential to fully assess the influence of climatic conditions on alpine spring water temperatures, such monitoring networks are currently almost entirely lacking in high mountain regions. 

 

Comment 4:

Page 6 (210 – 222): Too far-fetched conclusions based on one measurement series. Rather, it should be strongly noted that this is only the state for one measurement in 2021. There is no information about the air temperature at the tested springs, the temperature of the soils/rocks, the exposure of the source outflow, its shielding, shading

Response 4:

Thank you for your comment. In the first phrase of this paragraph is clearly stated that Figure 4 (and the corresponding analysis) is related to measurements in 2021, when a higher number of springs were sampled. Unfortunately, there are no meteorological stations in Retezat Mountains. Regarding the other comments we have described the protocol for measuring the spring temperatures in Subchapter 2.2. Field activities: ` Water temperature measurements were taken by shielding the spring from direct sunlight and 158 ensuring the probes did not come into contact with sediments, rocks, or vegetation. Each temperature measurement was recorded for at least 10 minutes, or until the temperature stabilized.`

 

Comment 5:

Page 7 (247 – 248): probably presented on the figure rather than observed on the figure

Response 5:

We replaced `observed` with `presented`.

 

Comment 6:

256: presented

Response 6:

We added `presented` to the sentence.

 

Comment 7:

264: these names should be on figure 7

Response 7:

As suggested, the names have now been added to the map and are visible in Figure 7.

 

Comment 8:

Figure 7: isohypse?

Response 8:

We confirm that 'contour lines' in our manuscript correspond to 'isohypses' (lines of equal elevation). We have modified this in the revised version to avoid confusion.

Reviewer 3 Report

Comments and Suggestions for Authors

The research analyzes the temperature of thirty-five springs in the marginal periglacial environment of the Carpathian Mountains and relates the temperature data obtained to the spatial distribution of permafrost in this area.

The work is highly original, mainly because it involves a subject of great scientific concern related to global temperature changes. The work seeks to analyze the temperature of springs in mountainous regions and establish a relationship between the spatial distribution of the temperatures obtained and the presence of permafrost. These areas are important sources of fresh water for the surrounding regions and present great fragilities associated with climate change, so investigations into the behavior of these water sources are fundamental for monitoring changes, as well as proposing methodological procedures for analysis in areas with similar characteristics.

The work adds to scientific research by detailing procedures applied to monitoring the temperature of springs, establishing thresholds for assessing the presence of permafrost in regions that are highly fragile to global warming and have discontinuous areas of permafrost, where traditional methods of modeling and assessing these areas are difficult to apply.

The discussion of the results is appropriate, bringing relationships with similar investigations carried out in other areas and even with applications of other methods in the field of research.

The conclusions presented are pertinent and present the general context of the main issues raised in the course of the work. It highlights the main issues found in the relationship between temperature data and its variation over the period analyzed, points out the concerns of direct applications in defining the existence of permafrost and indicates the use of other evaluation methods to confirm them.

The references used in the work are pertinent and meet the state of the art and the discussions presente.

 

As for the maps, the map in figure 1 could show the classification of the springs along with their location, as this would help interpret the data presented in the results.

Figure 7, even though the authors state that they have identified the glaciers mentioned in the paper, it is not possible to clearly identify them.

 

The classification of the springs is unclear. The work should present the procedures used to classify them more clearly and, as already mentioned, the classes should be shown on the map in figure 1.

Could the RS17 spring, which has a temperature variation considered an exception by the authors (lines 254 to 258), not be showing this behavior because it is very close to the rock glacier? Perhaps in a transition area?

Author Response

Dear Reviewer,

We greatly appreciate your thorough review and constructive feedback on our manuscript. Your insightful comments have been instrumental in improving the clarity and overall quality of our work. We have carefully addressed each of your suggestions and incorporated the necessary revisions into the updated manuscript. Below, we provide a detailed response to each of your comments, with line numbers referring to the version with tracked changes. We trust that our revisions adequately address your concerns and enhance the manuscript.
Thank you once again for your time and thoughtful review

 

Comment 1:

The research analyzes the temperature of thirty-five springs in the marginal periglacial environment of the Carpathian Mountains and relates the temperature data obtained to the spatial distribution of permafrost in this area.

The work is highly original, mainly because it involves a subject of great scientific concern related to global temperature changes. The work seeks to analyze the temperature of springs in mountainous regions and establish a relationship between the spatial distribution of the temperatures obtained and the presence of permafrost. These areas are important sources of fresh water for the surrounding regions and present great fragilities associated with climate change, so investigations into the behavior of these water sources are fundamental for monitoring changes, as well as proposing methodological procedures for analysis in areas with similar characteristics.

The work adds to scientific research by detailing procedures applied to monitoring the temperature of springs, establishing thresholds for assessing the presence of permafrost in regions that are highly fragile to global warming and have discontinuous areas of permafrost, where traditional methods of modeling and assessing these areas are difficult to apply.

The discussion of the results is appropriate, bringing relationships with similar investigations carried out in other areas and even with applications of other methods in the field of research.

The conclusions presented are pertinent and present the general context of the main issues raised in the course of the work. It highlights the main issues found in the relationship between temperature data and its variation over the period analyzed, points out the concerns of direct applications in defining the existence of permafrost and indicates the use of other evaluation methods to confirm them.

The references used in the work are pertinent and meet the state of the art and the discussions presente.

As for the maps, the map in figure 1 could show the classification of the springs along with their location, as this would help interpret the data presented in the results.

Response 1:

Thank you very much for this comment. As suggested, we have updated Figure 1 to include the classification of the springs along with their locations.

 

Comment 2:

Figure 7, even though the authors state that they have identified the glaciers mentioned in the paper, it is not possible to clearly identify them.

Response 2:

We have followed the suggestion and included the names of the rock glaciers directly on the map in Figure 7.

 

Comment 3:

The classification of the springs is unclear. The work should present the procedures used to classify them more clearly and, as already mentioned, the classes should be shown on the map in figure 1.

Response 3:

We added the following phrases: `Springs associated with rock glaciers are those emerging at the front or along the lateral margins of these landforms. Rock glaciers in the Retezat Mountains are composed of coarse debris and are at least 15-20 m thick [25]. Another common category of springs in the study area includes those seeping from other periglacial landforms, such as scree and talus slopes. While scree slopes are primarily composed of coarse debris are considerably thinner than rock glaciers, talus slopes in the Southern Carpathians typically consist of a mixture of fine and coarse sediments and are generally less than 10 m thick [41]. Springs without a clearly identifiable landform at their source but located on steep slopes (>15˚) covered by meadows were classified separately. Additionally, springs emerging from the relatively flat floors of glacial cirques and valleys were considered a distinct category. `

 

Comment 4:

Could the RS17 spring, which has a temperature variation considered an exception by the authors (lines 254 to 258), not be showing this behavior because it is very close to the rock glacier? Perhaps in a transition area?

Response 4:

Thank you for this suggestion. We added the following phrase: `As RS17 is located near the front of a rock glacier, its distinct thermal behavior could be attributed to its setting within a permafrost-affected transition zone.`

Reviewer 4 Report

Comments and Suggestions for Authors

This study investigates the summer water temperatures of 35 alpine springs in the Retezat Mountains, Southern Carpathians, from 2020 to 2023. It highlights that springs originating from rock glaciers are significantly colder and more thermally stable than those from other sources, with some maintaining temperatures below 2 °C. This paper is generally well-structured and easy to understand. I recommend a minor revision.

 

Some minor comments:
L10-31: the abstract would be stronger if it included a clearer quantitative summary of the findings. It would good to expand monitoring and inclusion of water chemistry but also briefly mention any current limitations of the study.

L20: “slightly exceeding 2 °C during summer” could consider giving a specific range if known.

L40: “glaciers, snow, and permafrost”, Consider reordering for flow: perhaps “snow, glaciers, and permafrost.”

L58–60: Consider making the thermal classification more readable by using bullet points or a table in the final layout, if allowed by the journal.

L106: “relate these findings to permafrost distribution”, rewording for clarity.

L202: “three springs,” but then list four (RS1, RS33, RS18, RS25). Please revise either the number or the list.

L215–216: Consider rephrasing for clarity. For example “Rock glacier and meadow springs exhibit narrower temperature ranges, suggesting more stable thermal regimes compared to the more variable scree/talus and valley floor springs.”

L209: Clarify whether 2021 is representative of all years monitored (2020–2023), or if 2021 was selected due to specific conditions.

L218: Maybe specify how many springs between 1900–2200 m showed temperatures above 4 °C. This would help the reader evaluate the conclusion.

L278–279: “below or slightly above 2 °C”, Could you give an exact temperature range here (e.g., 1.2–2.3 °C)?

L283–284: “The temperature increases at a rate…”, Consider rephrasing it.

L286–287: Instead of repeating all four glacier names, you might condense this sentence.

L373: “Unlike other studies…”, consider specifying one or two examples/citations for stronger contrast.

L375: “avoid potential anomalies caused by atypical climatic conditions” to: “…and reduce the influence of outlier years with unusual weather patterns.”

L379–380: “…streams, which may dry up or flow intermittently”, using the term “ephemeral streams” or “intermittent flow regimes” for more technical precision.

Author Response

Dear Reviewer,

Thank you very much for your valuable comments. We have addressed your requests by adding a new table and incorporating several additional clarifications throughout the manuscript. We believe that your suggestions have significantly improved the quality of the paper and have added value to the outcomes of our research. A detailed response to each of your comments is provided below:

 

Comment 1:

This study investigates the summer water temperatures of 35 alpine springs in the Retezat Mountains, Southern Carpathians, from 2020 to 2023. It highlights that springs originating from rock glaciers are significantly colder and more thermally stable than those from other sources, with some maintaining temperatures below 2 °C. This paper is generally well-structured and easy to understand. I recommend a minor revision.

Response 1:

Thank you for this general comment.

 

Comment 2:

Some minor comments:
L10-31: the abstract would be stronger if it included a clearer quantitative summary of the findings. It would good to expand monitoring and inclusion of water chemistry but also briefly mention any current limitations of the study.

Response 2:

We appreciate the reviewer`s suggestion. We added the following phrases: `During the four-year monitoring period, water temperatures across all springs ranged from 1.2 °C to 10.5 °C. Springs emerging from rock glaciers had the lowest average temperature (2.37 °C), while those on cirque and valley floors were the warmest (6.20 °C), followed closely by springs from meadow-covered slopes (6.20 °C) and those from scree and talus slopes (4.70 °C).`

As the abstract is already quite detailed, we have limited space for additional information. However, we have emphasized `the need for long-term monitoring`, which we consider the main limitation of this study. We also mentioned the potential for future `expanded investigations into water chemistry and discharge dynamics to improve our understanding of high-altitude hydrological systems.`

 

Comment 3:

L20: “slightly exceeding 2 °C during summer” could consider giving a specific range if known.

Response 3:

We added the following phrase: ` can lead to spring water temperatures ranging from 2 °C to 4 °C during summer.`

 

Comment 4:

L40: “glaciers, snow, and permafrost”, Consider reordering for flow: perhaps “snow, glaciers, and permafrost.”

Response 4:

In accordance with the recommendations, we ordered them as follows: `snow, glaciers, and permafrost.`

 

Comment 5:

L58–60: Consider making the thermal classification more readable by using bullet points or a table in the final layout, if allowed by the journal.

Response 5:

The thermal classification was organized into a table.

 

Comment 6:

L106: “relate these findings to permafrost distribution”, rewording for clarity.

Response 6:

We added the following phrase: `Therefore, our study aims to analyze the distribution of cold springs in late summer within a marginal periglacial environment of the Carpathian Mountains and to connect these observations with the distribution of permafrost.`

 

Comment 7:

L202: “three springs,” but then list four (RS1, RS33, RS18, RS25). Please revise either the number or the list.

Response 7:

We changed `three` to `four`.

 

Comment 8:

L215–216: Consider rephrasing for clarity. For example “Rock glacier and meadow springs exhibit narrower temperature ranges, suggesting more stable thermal regimes compared to the more variable scree/talus and valley floor springs.”

Response 8:

We added the following phrase: `Springs originating from rock glaciers and slopes covered with meadows indicating more stable thermal conditions, in contrast to the greater variability observed in springs from scree/talus slopes and valley floors.`

 

Comment 9:

L209: Clarify whether 2021 is representative of all years monitored (2020–2023), or if 2021 was selected due to specific conditions.

Response 9:

We added the following phrase: `Spring temperatures measured during summer 2021 using a portable digital thermometer are shown in Figure 4a. This year was selected for illustration as it represented the period with the greatest number of springs investigated. The data highlighted that the lowest values were recorded in springs originating from rock glaciers, followed by those from scree and talus slopes.`

 

Comment 10:

L218: Maybe specify how many springs between 1900–2200 m showed temperatures above 4 °C. This would help the reader evaluate the conclusion.

Response 10:

We added the number of springs with temperature above 4 °C:  `11`.

 

Comment 11:

L278–279: “below or slightly above 2 °C”, Could you give an exact temperature range here (e.g., 1.2–2.3 °C)?

Response 11:

The exact temperature range was added: `(e.g., 1.2 °C to 2.4 °C)`

 

Comment 12:

L283–284: “The temperature increases at a rate…”, Consider rephrasing it.

Response 12:

The rephrased version: `The temperature rises at a rate between 0.24 °C and 1 °C within the first 50 meters from the front of the rock glaciers.`

 

Comment 13:

L286–287: Instead of repeating all four glacier names, you might condense this sentence.

Response 13:

We rephrased accordingly: `Although spring temperatures at the front of the rock glaciers initially remain below the thermal threshold of 2 °C, they rise significantly over a short distance, surpassing the threshold for permafrost occurrence.`

 

Comment 14:

L373: “Unlike other studies…”, consider specifying one or two examples/citations for stronger contrast.

Response 14:

We added appropriate references. `Unlike other studies that measured alpine spring water temperatures in only a single season [27, 46], this study employed a longer recording period (2020 - 2023) to account for variations across multiple years and reduce the influence of outlier years with unusual weather patterns.`

 

Comment 15:

L375: “avoid potential anomalies caused by atypical climatic conditions” to: “…and reduce the influence of outlier years with unusual weather patterns.”

Response 15:

We rephrased accordingly and added the following text `and reduce the influence of outlier years with unusual weather patterns`

 

Comment 16:

L379–380: “…streams, which may dry up or flow intermittently”, using the term “ephemeral streams” or “intermittent flow regimes” for more technical precision.

Response 16:

We added the following phrase: `According to climate projections, the frequency of droughts in Europe is expected to increase by the end of the century [47], impacting the runoff of mountain streams, which may exhibit intermittent flow regimes [48].`