the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
Links between seasonal suprapermafrost groundwater, the hydrothermal change of the active layer, and river runoff in alpine permafrost watersheds
Jia Qin
Yongjian Ding
Tianding Han
Faxiang Shi
Qiudong Zhao
Yaping Chang
Junhao Cui
Abstract. The seasonal dynamic of suprapermafrost groundwater significantly affects runoff generation and concentration in permafrost basins and is a leading issue that must urgently be addressed in hydrological research in cold and alpine regions. In this study, the seasonal dynamic process of the suprapermafrost groundwater level (SGL), vertical gradient changes of soil temperature (ST) and moisture content in the active layer (AL), and river level changes were systematically analyzed at four permafrost watersheds in the Qinghai–Tibet Plateau using comparative analysis and the nonlinear correlation evaluation method. How freeze–thaw processes impact seasonal SGL, and the links between SGL and surface runoff, were also discussed. The SGL process in a hydrological year can be divided into four periods: (A) a rapid falling period (October–middle November), (B) a stable low-water period (late November–May), (C) a rapid rising period (approximately June), and (D) a stable high-water period (July–September), which synchronously respond to seasonal variations in soil moisture and temperature in the AL. The characteristics and causes of SGL changes varied significantly during the four different periods. The freeze-thaw process of the AL has crucial regulatory effects on SGL and surface runoff in permafrost watersheds. During Period A, with rapid AL freezing, the ST had a dominant impact on the SGL. In Period B, the AL was entirely frozen because of the stably low ST, and the SGL dropped to the lowest level with small changes. During Period C, ST in the deep soil layers of the active layer (below 50 cm depth) significantly impacted the SGL (nonlinear correlation coefficient R2>0.74, P<0.05), whereas the SGL change in the shallow soil layer (0–50 cm depth) had a closer relationship with soil moisture content. Rainfall was the major cause for the stable high SGL during Period D. In addition, the SGLs in Periods C and D were closely linked to the retreat and flood processes of river runoff. The SWL contributed approximately 57.0–65.8 % of the river runoff changes in Period D. These findings can provide references for hydrological research in permafrost basins and guide the rational development and utilization of water resources in cold and alpine regions.
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Jia Qin et al.
Status: final response (author comments only)
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RC1: 'Comment on egusphere-2023-1394', Anonymous Referee #1, 03 Aug 2023
The manuscript “Links between seasonal supra-permafrost groundwater, the hydrothermal change of the active layer, and river runoff in alpine permafrost watersheds” aims to describe how hydrothermal conditions in active layers affect supra-permafrost groundwater levels (SGL) and the corresponding effect on runoff generation.
The topic is very interesting and gets increasing attention in recent years given the projected climate change. The overall objective of the study is highly relevant and the authors also analyze the research question with valuable monitoring data from Qinghai–Tibet Plateau, finding the seasonal varying responses of SGL to soil temperature (ST) and soil volumetric moisture content (SVMC).
In spite of the above-mentioned interesting aspects, these analyses unfortunately do not live up to its potential. The research question and the novelty of this study are not well illustrated. The paper now is more like a technical report, rather than an academic research paper, and more in-depth analysis and discussion are needed to generate more interesting and robust insights.
As such, I do have several major concerns that need to be addressed in detail before it can be considered for publication. The comments and suggestions are listed as following, hopefully they will be helpful to improve the manuscript.
- The research question is not clear. In Introduction, authors invested quite some effort in showing the importance of supra-permafrost groundwater (SG), but much less in reviewing the status quo of SG dynamics and proposing specific scientific research questions. Such issues make the reader very confusing at the first glance of this paper. For instance, in lines 58-67, the authors listed the influencing factors of SG variation, but without presenting how these factors impact SG variations and what questions need to be solved. One sentence of “However, there is a shortfall in systematically revealing the linkage between the seasonal hydrothermal change of AL, SG, and surface runoff.” is far from enough.
- The structure of the manuscript needs a major overhaul as it is difficult to find a red line for each section or paragraph. For example, why is the Sigmoid–Boltzmann formula in Result? It should be in Methods and materials 2.4, and why this formula is used for analysis? What is the physical foundation behind? A polynomial cubic formula is used in line 205 while a sigmoid formula is used in line 186. What is the difference between these formulae; what is the key point in “3 Seasonal characteristics of SG”? Can you use one brief sentence at the beginning of each paragraph to give some general findings or ideas? Meanwhile, I may suggest change the old 3 into “Seasonal characteristics of SGL, ST, and SVMC”, and move related descriptions from 4 to 3. What’s more, the current Discussion is not a not real “discussion”, the authors showed the importance of SG again, but without presenting what’s new in this study compared with previous studies. Moreover, I do think the “framework” should be in “discussion” with a focus on what general or/and new patterns you have found, what processes are involved, and corresponding implications for future studies.
- More details are needed in Methods and materials to make sure the reliability of all results in this study. For example, (i) how to define the four different periods of SGL? What do you mean “tip points”? How to select the tip points in a scientific way? (ii) more detailed calibration procedures for SGL, SVMC, and ST sensors are also needed; (iii) how are the geographical distribution of observations for SGL, SVMC, and ST, meteorological variables and river level? SGL, ST, SVMC data were at point-scale, while the river level reflected the overall discharge at the catchment scale. How do authors consider scaling issues throughout the analysis? (iii) what is the hydrogeological condition in the study area? Is SG recharged by river or river is recharged by SG? Authors need to make it very clear. Otherwise, most readers will not be able to assess the results as well as the reasoning behind the interpretation.
- Four different stations with climatic gradients are selected in this study, a comparative analysis is thus expected for readers. However, almost nothing related is shown in this paper.
- More in-depth analyses are needed to illustrate the impact of ST and SVMC changes on SGL variations, the role of SG in regulating river runoff, and how SGL responses to rainfall events. Currently, most analyses are simple descriptions about the statistical relationship between variables.
- Pay attention to the consistency problems in this paper. For example, in lines 95-96, it says “the analysis was conducted in a hydrological year (from October 1 to September 30)”, while the time series in Figure 3 are contrasted with this, and also different with each other for each small figure. Meanwhile, such time series in Figure 3 are also different to those in Figure 2, making it hard for readers to follow expressions in line 132.
- The level of English does not yet meet the standard required for scientific publications and requires a detailed round of proof reading by a native English speaker with hydrology background.
Specific points:
L.12: what is runoff concentration here?
L.38: change into “it plays a crucial role in regulating land surface processes…”
L.39: what do you mean “the SG maintains a high value”, I suppose it should be the SGL?
A separated table with site-specific characteristics including location, altitude, vegetation type, annual mean precipitation, air temperature, soil properties, and so on, could better illustrate the gradient.
L.101: The writing should be more concise. Such expressions like “nearby national weather stations” without the distance are not reliable.
L.121-122: Refs are needed here for the method and algorithm.
L.126: change into the seasonal variation of SGL…
L.163-164: refs are needed to support your inferences.
L.233: use correlation analysis results to prove this.
L.299-300: refs are needed again.
L.317: only variables of ST and SVMC are considered for evaluating their effect on SGL changes, how could you get the conclusion that they are the primary impact factors.
Citation: https://doi.org/10.5194/egusphere-2023-1394-RC1 -
AC2: 'Reply on RC1', jia qin, 18 Sep 2023
Thank you very much for the comments and suggestions. All our authors have discussed the review comments and will carefully revise each item based on the opinions.
Reply to the following comments one by one.
- The research question is not clear. In Introduction, authors invested quite some effort in showing the importance of supra-permafrost groundwater (SG), but much less in reviewing the status quo of SG dynamics and proposing specific scientific research questions. Such issues make the reader very confusing at the first glance of this paper. For instance, in lines 58-67, the authors listed the influencing factors of SG variation, but without presenting how these factors impact SG variations and what questions need to be solved. One sentence of “However, there is a shortfall in systematically revealing the linkage between the seasonal hydrothermal change of AL, SG, and surface runoff.” is far from enough.
Reply: we agree with the reviewer, and will carefully revise the “Introduction”.
- The structure of the manuscript needs a major overhaul as it is difficult to find a red line for each section or paragraph. For example, why is the Sigmoid–Boltzmann formula in Result? It should be in Methods and materials 2.4, and why this formula is used for analysis? What is the physical foundation behind? A polynomial cubic formula is used in line 205 while a sigmoid formula is used in line 186. What is the difference between these formulae; what is the key point in “3 Seasonal characteristics of SG”? Can you use one brief sentence at the beginning of each paragraph to give some general findings or ideas? Meanwhile, I may suggest change the old 3 into “Seasonal characteristics of SGL, ST, and SVMC”, and move related descriptions from 4 to 3. What’s more, the current Discussion is not a not real “discussion”, the authors showed the importance of SG again, but without presenting what’s new in this study compared with previous studies. Moreover, I do think the “framework” should be in “discussion” with a focus on what general or/and new patterns you have found, what processes are involved, and corresponding implications for future studies.
Reply: We agree with the opinion and suggestion in “Discussion” section. We will rewrite the “Discussion” considering the reviewer’s comments. In addition, the section 3 will be revised to “Seasonal characteristics of SGL, ST, and SVMC”. The detailed instruction in section 3 and 4 will be revised correspondingly. The formulas selected in the text are based on the results of comparative analysis according to existing reference (Wang et al., 2012). We will move the formulas and instructions in section 4 to section 2.4, so as to make the structure more reasonable.
- More details are needed in Methods and materials to make sure the reliability of all results in this study. For example, (i) how to define the four different periods of SGL? What do you mean “tip points”? How to select the tip points in a scientific way? (ii) more detailed calibration procedures for SGL, SVMC, and ST sensors are also needed; (iii) how are the geographical distribution of observations for SGL, SVMC, and ST, meteorological variables and river level? SGL, ST, SVMC data were at point-scale, while the river level reflected the overall discharge at the catchment scale. How do authors consider scaling issues throughout the analysis? (iii) what is the hydrogeological condition in the study area? Is SG recharged by river or river is recharged by SG? Authors need to make it very clear. Otherwise, most readers will not be able to assess the results as well as the reasoning behind the interpretation.
Reply: thanks for the detailed comments and suggestions. After serious discussions, all our authors agreed with the reviewer’s opinion and will carefully revise the Methods and materials.
- Four different stations with climatic gradients are selected in this study, a comparative analysis is thus expected for readers. However, almost nothing related is shown in this paper.
Reply: thanks for the comment. The analysis in four different stations selected in this study was aim to shown common characteristics of the linkage between SG, ST, SVMC, and RL in alpine permafrost watersheds. So, the manuscript has weakened the difference.
- More in-depth analyses are needed to illustrate the impact of ST and SVMC changes on SGL variations, the role of SG in regulating river runoff, and how SGL responses to rainfall events. Currently, most analyses are simple descriptions about the statistical relationship between variables.
Reply: thanks, we will carefully revise the manuscript according to the reviewer’s comments and suggestions.
- Pay attention to the consistency problems in this paper. For example, in lines 95-96, it says “the analysis was conducted in a hydrological year (from October 1 to September 30)”, while the time series in Figure 3 are contrasted with this, and also different with each other for each small figure. Meanwhile, such time series in Figure 3 are also different to those in Figure 2, making it hard for readers to follow expressions in line 132.
Reply: thanks and we will revise the figures and text throughout the manuscript.
- The level of English does not yet meet the standard required for scientific publications and requires a detailed round of proof reading by a native English speaker with hydrology background.
Reply: thanks. The English of the manuscript has revised by expert English editors by “Editage”. To enhance the English, we will ask other English editor with hydrology background check and revise the proof again.
Specific points:
L.12: what is runoff concentration here?
Reply: the original meaning of the words in the sentence was to refer the runoff confluence. We will revise it.
L.38: change into “it plays a crucial role in regulating land surface processes…”
Reply: ok, we will revise it.
L.39: what do you mean “the SG maintains a high value”, I suppose it should be the SGL?
Reply: Thanks and we will replace SG by SGL.
A separated table with site-specific characteristics including location, altitude, vegetation type, annual mean precipitation, air temperature, soil properties, and so on, could better illustrate the gradient.
Reply: We will seriously consider the suggestion.
L.101: The writing should be more concise. Such expressions like “nearby national weather stations” without the distance are not reliable.
Reply: Thanks for the suggestion and we will check and revise the similar expressions.
L.121-122: Refs are needed here for the method and algorithm.
Reply: ok, we will revise it.
L.126: change into the seasonal variation of SGL…
Reply: ok, we will revise it.
L.163-164: refs are needed to support your inferences.
Reply: ok, we will revise it.
L.233: use correlation analysis results to prove this.
Reply: ok, we will revise it.
L.299-300: refs are needed again.
Reply: ok, we will revise it.
L.317: only variables of ST and SVMC are considered for evaluating their effect on SGL changes, how could you get the conclusion that they are the primary impact factors.
Reply: it is mainly because of the large correlation coefficient. We will check the expression and revise the corresponding sentences to make them more accurate.
Citation: https://doi.org/10.5194/egusphere-2023-1394-AC2
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RC2: 'Comment on egusphere-2023-1394', Anonymous Referee #2, 03 Aug 2023
The manuscript “Links between seasonal suprapermafrost groundwater, the hydrothermal change of the active layer, and river runoff in alpine permafrost watersheds” has systematically analyzed the impacts of freeze–thaw processes of active layer on seasonal suprapermafrost groundwater (SGL), and the links between SGL and surface runoff based on the field observations. The framework of watershed hydrology responding to the freeze-thaw of the permafrost active layer also was explored. The topic in interesting and this manuscript is significant in hydrological science in clod regions. The methods and the study conclusion are convincing. In my opinion, the manuscript is suitable for publishing in the HESS after some minor revisions concerning as follows:
- The English of the manuscript is good, while there are a few sentences which are too long and a bit complex. It is suggested to be separated in a few short sentences. For example, the sentence in line 214-217 “Although the SVMC and ST both have good relationships with the SGL below a depth of 70 cm, the variation scope of the SVMC is minimal, and the freezing process of deep soil determines the uplift process of the AL lower boundary, which affects the SGL. Therefore, the deep layer also more directly impacts the SGL owing to the ST.”
- The font of text and label in some Figures, such as the Figure 1 and Figure 4, are too small and not very clear. The color of the lines in the subtable of Figure 5b is inconsistent.
- The section “Discussion”. In the section, I recommend to add some discussions about the different impacts of vegetation and the slope on SGL dynamics, although they maybe not affect the conclusion of the study.
- Line 337, one more space in “The change----”.
- Line 58 and Line 62, the SG should be SGL?
- In line 96, the “---in a hydrological year”. Does it refer a specific year or the annual average value?
- Why the data of station HLG was not shown in Figure 3? No data or other reasons? It should be introduced in the text.
Citation: https://doi.org/10.5194/egusphere-2023-1394-RC2 -
AC1: 'Reply on RC2', jia qin, 15 Sep 2023
1. The English of the manuscript is good, while there are a few sentences which are too long and a bit complex. It is suggested to be separated in a few short sentences. For example, the sentence in line 214-217 “Although the SVMC and ST both have good relationships with the SGL below a depth of 70 cm, the variation scope of the SVMC is minimal, and the freezing process of deep soil determines the uplift process of the AL lower boundary, which affects the SGL. Therefore, the deep layer also more directly impacts the SGL owing to the ST.”
Reply: We all authors agree with the opinion. We will revise the sentences and do a detailed round of proof reading by a native English speaker with hydrology background.
2.The font of text and label in some Figures, such as the Figure 1 and Figure 4, are too small and not very clear. The color of the lines in the subtable of Figure 5b is inconsistent.
Reply: Thank for the opinion and we will accordingly revise the figures.
3. The section “Discussion”. In the section, I recommend to add some discussions about the different impacts of vegetation and the slope on SGL dynamics, although they maybe not affect the conclusion of the study.
Reply: it is a good suggestion. We will consider the impacts of vegetation and slope on the SGL changes, and revise the “Discussion” section accordingly.
4. Line 337, one more space in “The change----”.
Reply: thanks, we will revise it.
5. Line 58 and Line 62, the SG should be SGL?
Reply: that is right, and we will revise it.
6. In line 96, the “---in a hydrological year”. Does it refer a specific year or the annual average value?
Reply: it refers to a specific hydrological year because of the data limitation. We will add detailed information in the section “Experimental data”.
7. Why the data of station HLG was not shown in Figure 3? No data or other reasons? It should be introduced in the text.
Reply: The data of ST anf SVMC in the HLG station is missing. We will check the data again or use interpolation of data in nearby stations to supplement the missing data. The corresponding instruction will be added in the text.
Citation: https://doi.org/10.5194/egusphere-2023-1394-AC1
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