the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
| 02 Sep 2024
Brief communication: Morphometric control on the frequency of snow avalanches on the left bank slope of the Tongquan River, southeastern Tibetan Plateau, China
Abstract. Understanding the frequency of occurrence and mechanisms controlling snow avalanches (hereafter referred to as avalanches) is crucial for effective disaster prevention and mitigation, especially in the context of climate warming. In this study, the topographic features and historical activities within the four avalanche paths on the left bank slope of the Tongquan River are meticulously analysed through a comprehensive approach that combines field investigations, long-term remote sensing interpretation, and spatial analysis. Additionally, the morphometric controls on avalanche frequency are further investigated. The results indicate that the occurrence frequencies of the four avalanche paths on the same slope, despite having nearly identical macrometeorological and climatic conditions, are not uniform. This variation depends on morphometric factors, such as the size of the starting zone and slope orientation.
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Status: closed
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RC1: 'Comment on egusphere-2024-1913', Anonymous Referee #1, 03 Oct 2024
1) The authors should elaborate in more detail on where the snow avalanche sliding surface is located. Is the sliding surface inside the snowpack, or does it occur at the interface between the snowpack and the hillslope soil/bedrock? If it occurs inside the snowpack, then the significance of analyzing the hillslope landscape should be reconsidered, and an analysis of the mechanical properties of the snowpack should be added to discuss, and explain the differences in the frequency of avalanches.
2). According to Figure 2, snow avalanches show a strong correlation with season (temperature), and slope aspect (solar irradiation), it is better for the authors to provide a more detailed discussion on these points.
Citation: https://doi.org/10.5194/egusphere-2024-1913-RC1 -
AC1: 'Reply on RC1', Hong Wen, 20 Oct 2024
Remark #1. The authors should elaborate in more detail on where the snow avalanche sliding surface is located. Is the sliding surface inside the snowpack, or does it occur at the interface between the snowpack and the hillslope soil/bedrock? If it occurs inside the snowpack, then the significance of analyzing the hillslope landscape should be reconsidered, and an analysis of the mechanical properties of the snowpack should be added to discuss, and explain the differences in the frequency of avalanches.
Response: Thank you very much for your insightful comments and suggestions. The avalanche starting zone in the study area is characterized by seasonal snow cover, where sliding can occur both within the snowpack (surface avalanche) and at the interface between the snowpack and the underlying bedrock (full-depth avalanche). When sliding transpires within the snowpack, it typically follows a mechanism in which lower layers of snow conform to the irregularities of the hillslope, thereby enabling upper layers to slip and potentially trigger an avalanche. Moreover, full-depth avalanches initiate directly at the interface between the snowpack and bedrock. Both types of avalanches are significantly influenced by local topographical features.
In our manuscript, we specifically analyzed terrain characteristics of the starting zone, including surface roughness, slope aspect, and curvature, to underscore their importance in avalanche formation. We contend that these terrain factors are essential for understanding avalanche frequency, irrespective of the location of the sliding surface, as they exert a direct influence on snow accumulation and stability. However, in response to your suggestion, we will broaden our discussion to encompass the mechanical properties of the snowpack to elucidate further the variations in avalanche frequency.
Remark #2. According to Figure 2, snow avalanches show a strong correlation with season (temperature), and slope aspect (solar irradiation), it is better for the authors to provide a more detailed discussion on these points.
Response: Thank you for your insightful feedback. We appreciate your suggestion to expand the discussion on the relationship between snow avalanches, seasonal temperature variations, and slope aspect (solar irradiation). Avalanches in our study area indeed exhibit a strong seasonal pattern, with temperature playing a critical role in snowpack stability. Warmer temperatures during late winter and spring, particularly on sun-exposed slopes, often result in increased snowmelt and snowpack destabilization, triggering avalanches. Slope aspect further amplifies this effect by regulating the amount of solar radiation received. For example, south-facing slopes typically receive more sunlight, which accelerates snowmelt and weakens the snowpack, making them more prone to avalanches compared to north-facing slopes.
In the revised manuscript, we will provide a comprehensive analysis of how these factors—seasonal temperature fluctuations and slope aspect—interact to influence avalanche occurrences. Furthermore, we will elaborate on the impact of solar irradiation on snow stability and avalanche frequency across various slope aspects. We assert that these enhancements will contribute to a more profound understanding of the critical factors driving avalanche activity in our study area.
Citation: https://doi.org/10.5194/egusphere-2024-1913-AC1
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AC1: 'Reply on RC1', Hong Wen, 20 Oct 2024
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RC2: 'Comment on egusphere-2024-1913', Anonymous Referee #2, 03 Oct 2024
This manuscript presents a case study focused on avalanche activity in a local area, but it suffers from several limitations that diminish its broader applicability and scientific contribution.
The study is highly localized, and while it offers detailed insights into a specific set of avalanche paths, the conclusions drawn are difficult to generalize. The findings related to topographic and climatic variations are well-known factors influencing avalanches, and the manuscript does little to expand on existing research beyond confirming these established principles. Additionally, the reliance on a small set of avalanche paths (only four) limits the robustness of the analysis, as the patterns observed might not hold in more varied or complex terrain.
Second, the study’s methodology, particularly its use of optical images over a 37-year period, lacks detail about the resolution and potential biases in interpreting the avalanche paths. Without addressing these limitations, the reliability of the historical data is questionable, particularly in terms of the accuracy of avalanche detection across different paths. The discussion relies heavily on referencing past studies without integrating the new insights gained from this research. For example, while slope orientation and solar radiation are discussed at length, these are well-established drivers of snowpack behavior. The manuscript fails to bring innovative approaches or novel methodologies to further explore or quantify these factors. The analysis could be enhanced by incorporating more sophisticated modeling techniques or a broader dataset to make the results more widely applicable.
Finally, the manuscript lacks depth in discussing the limitations of its own approach. No substantial effort is made to address uncertainties in the data, the potential for variability in the local microclimate, or the effects of changing climate conditions on avalanche frequency over time, all of which are crucial aspects of avalanche studies today. I recommend submitting the article to a regional journal where it would be better suited.
Citation: https://doi.org/10.5194/egusphere-2024-1913-RC2 -
AC2: 'Reply on RC2', Hong Wen, 20 Oct 2024
Remark #1. This manuscript presents a case study focused on avalanche activity in a local area, but it suffers from several limitations that diminish its broader applicability and scientific contribution.
The study is highly localized, and while it offers detailed insights into a specific set of avalanche paths, the conclusions drawn are difficult to generalize. The findings related to topographic and climatic variations are well-known factors influencing avalanches, and the manuscript does little to expand on existing research beyond confirming these established principles. Additionally, the reliance on a small set of avalanche paths (only four) limits the robustness of the analysis, as the patterns observed might not hold in more varied or complex terrain.
Response: Thank you for your valuable feedback. While the study is indeed centered on a specific area with a small set of avalanche paths, the data we gathered through manual remote sensing interpretation of nearly 37 years of historical avalanche activity is substantial. We believe this provides valuable terrain-specific insights that can inform larger-scale investigations. This is why we are presenting it as a "short communication". Our primary objective was to examine how topographic and climatic factors influence avalanche activity in this unique region, and we hope that our findings offer a basis for broader applications. Despite its focused nature, the detailed analysis of localized patterns contributes to the understanding of how these processes operate in different terrains, particularly in under-researched areas like the southeastern Tibetan Plateau.
We also recognize the concerns regarding the broader applicability of our findings. To address this, we will revise the manuscript to better position our research within the wider scope of avalanche studies. We will highlight the potential for applying the methods and insights developed here to regions with different topographic and climatic conditions.
Remark #2. Second, the study’s methodology, particularly its use of optical images over a 37-year period, lacks detail about the resolution and potential biases in interpreting the avalanche paths. Without addressing these limitations, the reliability of the historical data is questionable, particularly in terms of the accuracy of avalanche detection across different paths. The discussion relies heavily on referencing past studies without integrating the new insights gained from this research. For example, while slope orientation and solar radiation are discussed at length, these are well-established drivers of snowpack behavior. The manuscript fails to bring innovative approaches or novel methodologies to further explore or quantify these factors. The analysis could be enhanced by incorporating more sophisticated modeling techniques or a broader dataset to make the results more widely applicable.
Response: Thank you for your constructive feedback. We fully understand your concerns regarding the methodology and the potential limitations of using optical imagery over a 37-year period. To mitigate this issue, we employed manual interpretation in our initial analysis to standardize the criteria used for identifying avalanche flow paths. In response to your comments, we will revise the manuscript to provide more detailed information about the resolution of the optical imagery used and further discuss the limitations this may pose for interpreting historical avalanche activity.
Regarding the discussion of well-known factors like slope orientation and solar radiation, we agree that these are established drivers of snowpack behavior. However, our study aims to contextualize these factors within the specific topographic and climatic conditions of the southeastern Tibetan Plateau, an under-researched region. Nonetheless, we acknowledge that the manuscript could benefit from a more innovative approach. Although we have explored NDSI (Normalized Difference Snow Index)-based remote sensing methods, our tests reveal that they fall short in accuracy compared to manual interpretation. We will revise the discussion to better incorporate the new insights from our study and pursue a more rigorous quantification of the effects of topographic factors. Thank you once again for your invaluable input, which will certainly help us improve the quality of the manuscript.
Remark #3. Finally, the manuscript lacks depth in discussing the limitations of its own approach. No substantial effort is made to address uncertainties in the data, the potential for variability in the local microclimate, or the effects of changing climate conditions on avalanche frequency over time, all of which are crucial aspects of avalanche studies today. I recommend submitting the article to a regional journal where it would be better suited.
Response: Thank you for your detailed feedback. We appreciate your suggestion to strengthen the discussion on uncertainties in the data, local microclimate variability, and the effects of changing climate conditions on avalanche frequency over time. In response, we will expand the manuscript to more thoroughly discuss these critical aspects. Specifically, we will address uncertainties related to data interpretation and avalanche detection, as well as the challenges posed by microclimatic variability in our study area. Additionally, we will include a more in-depth analysis of how climate change may be influencing avalanche frequency, particularly in the context of seasonal snowpack behavior and temperature variations, which are key factors in our study. Thank you again for your valuable input.
Citation: https://doi.org/10.5194/egusphere-2024-1913-AC2
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AC2: 'Reply on RC2', Hong Wen, 20 Oct 2024
Status: closed
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RC1: 'Comment on egusphere-2024-1913', Anonymous Referee #1, 03 Oct 2024
1) The authors should elaborate in more detail on where the snow avalanche sliding surface is located. Is the sliding surface inside the snowpack, or does it occur at the interface between the snowpack and the hillslope soil/bedrock? If it occurs inside the snowpack, then the significance of analyzing the hillslope landscape should be reconsidered, and an analysis of the mechanical properties of the snowpack should be added to discuss, and explain the differences in the frequency of avalanches.
2). According to Figure 2, snow avalanches show a strong correlation with season (temperature), and slope aspect (solar irradiation), it is better for the authors to provide a more detailed discussion on these points.
Citation: https://doi.org/10.5194/egusphere-2024-1913-RC1 -
AC1: 'Reply on RC1', Hong Wen, 20 Oct 2024
Remark #1. The authors should elaborate in more detail on where the snow avalanche sliding surface is located. Is the sliding surface inside the snowpack, or does it occur at the interface between the snowpack and the hillslope soil/bedrock? If it occurs inside the snowpack, then the significance of analyzing the hillslope landscape should be reconsidered, and an analysis of the mechanical properties of the snowpack should be added to discuss, and explain the differences in the frequency of avalanches.
Response: Thank you very much for your insightful comments and suggestions. The avalanche starting zone in the study area is characterized by seasonal snow cover, where sliding can occur both within the snowpack (surface avalanche) and at the interface between the snowpack and the underlying bedrock (full-depth avalanche). When sliding transpires within the snowpack, it typically follows a mechanism in which lower layers of snow conform to the irregularities of the hillslope, thereby enabling upper layers to slip and potentially trigger an avalanche. Moreover, full-depth avalanches initiate directly at the interface between the snowpack and bedrock. Both types of avalanches are significantly influenced by local topographical features.
In our manuscript, we specifically analyzed terrain characteristics of the starting zone, including surface roughness, slope aspect, and curvature, to underscore their importance in avalanche formation. We contend that these terrain factors are essential for understanding avalanche frequency, irrespective of the location of the sliding surface, as they exert a direct influence on snow accumulation and stability. However, in response to your suggestion, we will broaden our discussion to encompass the mechanical properties of the snowpack to elucidate further the variations in avalanche frequency.
Remark #2. According to Figure 2, snow avalanches show a strong correlation with season (temperature), and slope aspect (solar irradiation), it is better for the authors to provide a more detailed discussion on these points.
Response: Thank you for your insightful feedback. We appreciate your suggestion to expand the discussion on the relationship between snow avalanches, seasonal temperature variations, and slope aspect (solar irradiation). Avalanches in our study area indeed exhibit a strong seasonal pattern, with temperature playing a critical role in snowpack stability. Warmer temperatures during late winter and spring, particularly on sun-exposed slopes, often result in increased snowmelt and snowpack destabilization, triggering avalanches. Slope aspect further amplifies this effect by regulating the amount of solar radiation received. For example, south-facing slopes typically receive more sunlight, which accelerates snowmelt and weakens the snowpack, making them more prone to avalanches compared to north-facing slopes.
In the revised manuscript, we will provide a comprehensive analysis of how these factors—seasonal temperature fluctuations and slope aspect—interact to influence avalanche occurrences. Furthermore, we will elaborate on the impact of solar irradiation on snow stability and avalanche frequency across various slope aspects. We assert that these enhancements will contribute to a more profound understanding of the critical factors driving avalanche activity in our study area.
Citation: https://doi.org/10.5194/egusphere-2024-1913-AC1
-
AC1: 'Reply on RC1', Hong Wen, 20 Oct 2024
-
RC2: 'Comment on egusphere-2024-1913', Anonymous Referee #2, 03 Oct 2024
This manuscript presents a case study focused on avalanche activity in a local area, but it suffers from several limitations that diminish its broader applicability and scientific contribution.
The study is highly localized, and while it offers detailed insights into a specific set of avalanche paths, the conclusions drawn are difficult to generalize. The findings related to topographic and climatic variations are well-known factors influencing avalanches, and the manuscript does little to expand on existing research beyond confirming these established principles. Additionally, the reliance on a small set of avalanche paths (only four) limits the robustness of the analysis, as the patterns observed might not hold in more varied or complex terrain.
Second, the study’s methodology, particularly its use of optical images over a 37-year period, lacks detail about the resolution and potential biases in interpreting the avalanche paths. Without addressing these limitations, the reliability of the historical data is questionable, particularly in terms of the accuracy of avalanche detection across different paths. The discussion relies heavily on referencing past studies without integrating the new insights gained from this research. For example, while slope orientation and solar radiation are discussed at length, these are well-established drivers of snowpack behavior. The manuscript fails to bring innovative approaches or novel methodologies to further explore or quantify these factors. The analysis could be enhanced by incorporating more sophisticated modeling techniques or a broader dataset to make the results more widely applicable.
Finally, the manuscript lacks depth in discussing the limitations of its own approach. No substantial effort is made to address uncertainties in the data, the potential for variability in the local microclimate, or the effects of changing climate conditions on avalanche frequency over time, all of which are crucial aspects of avalanche studies today. I recommend submitting the article to a regional journal where it would be better suited.
Citation: https://doi.org/10.5194/egusphere-2024-1913-RC2 -
AC2: 'Reply on RC2', Hong Wen, 20 Oct 2024
Remark #1. This manuscript presents a case study focused on avalanche activity in a local area, but it suffers from several limitations that diminish its broader applicability and scientific contribution.
The study is highly localized, and while it offers detailed insights into a specific set of avalanche paths, the conclusions drawn are difficult to generalize. The findings related to topographic and climatic variations are well-known factors influencing avalanches, and the manuscript does little to expand on existing research beyond confirming these established principles. Additionally, the reliance on a small set of avalanche paths (only four) limits the robustness of the analysis, as the patterns observed might not hold in more varied or complex terrain.
Response: Thank you for your valuable feedback. While the study is indeed centered on a specific area with a small set of avalanche paths, the data we gathered through manual remote sensing interpretation of nearly 37 years of historical avalanche activity is substantial. We believe this provides valuable terrain-specific insights that can inform larger-scale investigations. This is why we are presenting it as a "short communication". Our primary objective was to examine how topographic and climatic factors influence avalanche activity in this unique region, and we hope that our findings offer a basis for broader applications. Despite its focused nature, the detailed analysis of localized patterns contributes to the understanding of how these processes operate in different terrains, particularly in under-researched areas like the southeastern Tibetan Plateau.
We also recognize the concerns regarding the broader applicability of our findings. To address this, we will revise the manuscript to better position our research within the wider scope of avalanche studies. We will highlight the potential for applying the methods and insights developed here to regions with different topographic and climatic conditions.
Remark #2. Second, the study’s methodology, particularly its use of optical images over a 37-year period, lacks detail about the resolution and potential biases in interpreting the avalanche paths. Without addressing these limitations, the reliability of the historical data is questionable, particularly in terms of the accuracy of avalanche detection across different paths. The discussion relies heavily on referencing past studies without integrating the new insights gained from this research. For example, while slope orientation and solar radiation are discussed at length, these are well-established drivers of snowpack behavior. The manuscript fails to bring innovative approaches or novel methodologies to further explore or quantify these factors. The analysis could be enhanced by incorporating more sophisticated modeling techniques or a broader dataset to make the results more widely applicable.
Response: Thank you for your constructive feedback. We fully understand your concerns regarding the methodology and the potential limitations of using optical imagery over a 37-year period. To mitigate this issue, we employed manual interpretation in our initial analysis to standardize the criteria used for identifying avalanche flow paths. In response to your comments, we will revise the manuscript to provide more detailed information about the resolution of the optical imagery used and further discuss the limitations this may pose for interpreting historical avalanche activity.
Regarding the discussion of well-known factors like slope orientation and solar radiation, we agree that these are established drivers of snowpack behavior. However, our study aims to contextualize these factors within the specific topographic and climatic conditions of the southeastern Tibetan Plateau, an under-researched region. Nonetheless, we acknowledge that the manuscript could benefit from a more innovative approach. Although we have explored NDSI (Normalized Difference Snow Index)-based remote sensing methods, our tests reveal that they fall short in accuracy compared to manual interpretation. We will revise the discussion to better incorporate the new insights from our study and pursue a more rigorous quantification of the effects of topographic factors. Thank you once again for your invaluable input, which will certainly help us improve the quality of the manuscript.
Remark #3. Finally, the manuscript lacks depth in discussing the limitations of its own approach. No substantial effort is made to address uncertainties in the data, the potential for variability in the local microclimate, or the effects of changing climate conditions on avalanche frequency over time, all of which are crucial aspects of avalanche studies today. I recommend submitting the article to a regional journal where it would be better suited.
Response: Thank you for your detailed feedback. We appreciate your suggestion to strengthen the discussion on uncertainties in the data, local microclimate variability, and the effects of changing climate conditions on avalanche frequency over time. In response, we will expand the manuscript to more thoroughly discuss these critical aspects. Specifically, we will address uncertainties related to data interpretation and avalanche detection, as well as the challenges posed by microclimatic variability in our study area. Additionally, we will include a more in-depth analysis of how climate change may be influencing avalanche frequency, particularly in the context of seasonal snowpack behavior and temperature variations, which are key factors in our study. Thank you again for your valuable input.
Citation: https://doi.org/10.5194/egusphere-2024-1913-AC2
-
AC2: 'Reply on RC2', Hong Wen, 20 Oct 2024
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