the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
| 22 Dec 2021
Comparing the runoff decompositions of small testbed catchments: end-member mixing analysis against hydrological modelling
Abstract. This study is focused on the comparison of catchment streamflow composition simulated with three well-known rainfall-runoff (RR) models (ECOMAG, HBV, SWAT) against hydrograph decomposition onto the principal constituents evaluated from End-Member Mixing Analysis (EMMA). There used the data provided by the short-term in-situ observations at two small mountain-taiga experimental catchments located in the south of Pacific Russia. All used RR models demonstrate that two neighboring small catchments disagree significantly in mutual dynamics of the runoff fractions due to geological and landscape structure differences. The geochemical analysis confirmed the differences in runoff generation processes at both studied catchments. The assessment of proximity of the runoff constituents to the hydrograph decomposition with the EMMA that makes a basis for the RR models benchmark analysis. We applied three data aggregation intervals (season, month and pentad) to find a reasonable data generalization period ensuring results clarity. In terms of runoff composition, the most conformable RR model to EMMA is found to be ECOMAG, HBV gets close to reflect specific runoff events well enough, SWAT gives distinctive behavior against other models. The study shows that along with using the standard efficiency criteria reflected proximity of simulated and modelling values of runoff, compliance with the EMMA results might give useful auxiliary information for hydrological modelling results validation.
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RC1: 'Comment on hess-2021-626', Anonymous Referee #1, 08 Feb 2022
I know I should start the review by summarizing the main characteristics of the paper, but I was unable to discern any.
I broke off the review at page 5 because this paper is too carelessly prepared. The English is very difficult to understand, the HESS guidelines have been poorly adhered to.
Furthermore, the paper has fundamental weaknesses. The issues raised in the Introduction cannot be addressed by a study that relies on two small catchments located very close to each other. The paper criticizes the use of empirical relations in hydrological modelling, then relies on empirical relationships itself. Parts of the methodology are poorly and/or incompletely explained.
Given these problems, I do not think it is worthwhile to spend more time on this paper. I am sorry for this, but I am simply losing too much time struggling through the text.
Below are the comments that I was able to make.
English editing is needed. I found 4 grammatical errors in the first paragraph alone and stopped checking them after that because I do not have the time:
l.23: takes -> take
l.24: extrapolating -> extrapolated
l.26-27: challenge task -> a challenging task
l.29: ...for validation flow pathways and residence times...: I do not understand what you are trying to say.
l.37-38: ...evolving model... top-down strategy: I do not understand.
l.40: You claim that catchment hydrology is still very much empirical by quoting a single reference that is over 36 years old! This statement has no credibility at all.
l.42-43: ..the scale-dependency of HRU-based model ... small-scale physical laws... The English is so warped I cannot understand this.
l.50: ground flow -> groundwater flow
l.54-55: There are a number of examples...lack of suitable data sets. It is unclear to me what this means, but the second part seems to contradict the first part.
l.58-59: How can you rank models based on processes?
l.60: ...based on solutions of direct or inverse task of modeling... Forward modeling and inverse modeling are completely differen activities with very different goals. Why are you using them as if they are similar?
l.61-65: We can read the section headings, so there is no need to provide a table of contents. Instead, formulate the objective of the paper.
l.67-69: In the Introduction you criticized essentially all hydrological modles developed so far, yet you only test them on two very small catchments that are very close to each other, and are probably too small for a model relying on hydrological response units. So you cannot consider the performance for different climates, land use, geography, or size. What is the point of this study then, as related to the issues you raised in the Introduction?
l.77: You are at the same elevation as Hokkaido and you have very cold winters. Is it really tropical there?
l.84: Without explaining the symbols, equations are meaningless.
l.86: I checked the reference to find out about the fair profiles number but could not find an explanation. But I found an extensive modeling exercise with ECOMAG. To what extent does this paper repeat this reference?
l.91: The suction you apply in such instruments determines which part of the pore space you sample, but you do not report this.
Suction cups cannot sample macropores unless these remain filled for a long period of time, which is typically not the case in unsaturated soils. Did your soils have macropores?
Did you remove these during the winter? (I am not sure they survive when they freeze.)
l.96: ...Data quality control suggested next simulation periods... How exactly?
l.97, 98, 161, 181: unexplained abbreviations.
l.108-109: The end-member mixing analysis...hydrology methods... Unclear.
l.110: ... hereafter called fractions... A fraction is very different from a source. You need to explain better what exactly you are doing.
l.112: ...some empirical relations... Vague. And in the Introduction you stated that reliance on empirics was a weakness of current models.
l.123-124: ...water quality... I believe you mean the various substances dissolved in the water.
l.126-130: This explanation of the use of bivariate scatter plots needs to be explained much clearer. What property exactly are you plotting? Concentrations, fluxes, loads during a given period? And when you state all possible combinations need to be plotted a assume you mean all possible combinations of two, i.e., only solute pairs will be plotted.
What will be the effect on colinearity if one solute is non-sorbing and the other is adsorbed? Both can still be conservative.
l.179: Please consult the guidelines for authors on the use of abbreviations in equations and the font of variables.
Citation: https://doi.org/10.5194/hess-2021-626-RC1 -
AC1: 'Reply on RC1', Andrey Bugaets, 16 Mar 2022
The comment was uploaded in the form of a supplement: https://hess.copernicus.org/preprints/hess-2021-626/hess-2021-626-AC1-supplement.pdf
-
AC1: 'Reply on RC1', Andrey Bugaets, 16 Mar 2022
-
RC2: 'Comment on hess-2021-626', Anonymous Referee #2, 16 Feb 2022
This manuscript details a study that compares runoff decomposition as estimated by end-member mixing analysis on one hand and hydrological models on the other hand. This issue is clearly of great interest for both hydrological processes understanding and model development. At this stage, the paper has several shortcomings in terms of methods and data, which prevents a full understanding of the paper. My suggestion would be to be less ambitious, e.g. in the number of hydrological models used but more exhaustive in the details given throughout the manuscript. Additionally, it should be noted that the English level is pretty poor, I am not a native English speaker but I recommend that the authors proofread their revised manuscript before submission.
Major comments
- Lack of details
Throughout the paper, there is a lack of details. This affects both the data/method section and the results/discussion section at a level that precludes the reader to provide clear guidelines for further improvements. The required additional information is listed in the minor comments hereafter. The two other major comments are related to methodological issues.
- Hydrological model uncertainties and how the methodology of the paper reduces it
As explained in the introduction (l.31-39), hydrograph decomposition may be a powerful tool to reduce equifinality. In this sense, the present study shows relatively similar runoff simulations but with different flow components from hydrological models, but with different flow components. Unfortunately, the authors did not take this opportunity seriously, they used a single optimal parameter set for each model and did not discuss the impact of this choice, nor the way the parameter set is optimized. Consequently, it is pretty hard to conclude the relative weights of structural and parameter uncertainties in explaining the results.
- Short record periods
Only three years are available for model simulation (what about the warm-up year?). It is quite short and consequently, no validation was performed by the authors. Modeling results are presented only for calibration, which is problematic when dealing with parameter/structural uncertainties. Also, as low-flow components are extracted from hydrological models simulations, the authors should verify cautionly model initialization.
Minor (but still important) comments
l.77-78: not clear what is the time step of heavy rainfall and how extreme are these events.
l.79: not clear how averaging is performed, spatial or temporal?
Please add a table with both catchments characteristics (mean annual rainfall, temperature, runoff, land use lithology, topography, etc.). The differences in runoff yields for these two neighbor catchments are huge and I cannot figure out if it is due to lithological differences or specificity of the (short) record periods with extreme events.
Figure 1. Where the WMO station is located?
l.132: It is not clear how the end members are identified, what is the "independent information"?
Please add a table with the characteristics of the three hydrological models (with e.g. basis of the snow components, number of free parameters, spatial and temporal discretization, etc.). The information given for each model is not homogenous. Nothing is said on parameter estimation, which is in my opinion a key issue (see major comment #2).
l.238-249: Are the results are shown in calibration (and by the way, how the calibration is performed)?? Please modify Figure 5 so that the reader can see the whole record period simulation results.
Table 4: it appears that the models present quite different flow decompositions. Could this be due to the fact that the a priori three-component is wrong because too detailed for such small catchments? Since many flow decompositions only concern two flow components ("baseflow" and "surface flow"), did the authors challenge their prior 3-components hypothesis?
l.359-360: These perspectives are quite fuzzy. Please provide a real discussion section in the paper. There is a lot to say on both methodological limitations and further analysis of the results obtained.
Citation: https://doi.org/10.5194/hess-2021-626-RC2 -
AC2: 'Reply on RC2', Andrey Bugaets, 16 Mar 2022
The comment was uploaded in the form of a supplement: https://hess.copernicus.org/preprints/hess-2021-626/hess-2021-626-AC2-supplement.pdf
Status: closed
-
RC1: 'Comment on hess-2021-626', Anonymous Referee #1, 08 Feb 2022
I know I should start the review by summarizing the main characteristics of the paper, but I was unable to discern any.
I broke off the review at page 5 because this paper is too carelessly prepared. The English is very difficult to understand, the HESS guidelines have been poorly adhered to.
Furthermore, the paper has fundamental weaknesses. The issues raised in the Introduction cannot be addressed by a study that relies on two small catchments located very close to each other. The paper criticizes the use of empirical relations in hydrological modelling, then relies on empirical relationships itself. Parts of the methodology are poorly and/or incompletely explained.
Given these problems, I do not think it is worthwhile to spend more time on this paper. I am sorry for this, but I am simply losing too much time struggling through the text.
Below are the comments that I was able to make.
English editing is needed. I found 4 grammatical errors in the first paragraph alone and stopped checking them after that because I do not have the time:
l.23: takes -> take
l.24: extrapolating -> extrapolated
l.26-27: challenge task -> a challenging task
l.29: ...for validation flow pathways and residence times...: I do not understand what you are trying to say.
l.37-38: ...evolving model... top-down strategy: I do not understand.
l.40: You claim that catchment hydrology is still very much empirical by quoting a single reference that is over 36 years old! This statement has no credibility at all.
l.42-43: ..the scale-dependency of HRU-based model ... small-scale physical laws... The English is so warped I cannot understand this.
l.50: ground flow -> groundwater flow
l.54-55: There are a number of examples...lack of suitable data sets. It is unclear to me what this means, but the second part seems to contradict the first part.
l.58-59: How can you rank models based on processes?
l.60: ...based on solutions of direct or inverse task of modeling... Forward modeling and inverse modeling are completely differen activities with very different goals. Why are you using them as if they are similar?
l.61-65: We can read the section headings, so there is no need to provide a table of contents. Instead, formulate the objective of the paper.
l.67-69: In the Introduction you criticized essentially all hydrological modles developed so far, yet you only test them on two very small catchments that are very close to each other, and are probably too small for a model relying on hydrological response units. So you cannot consider the performance for different climates, land use, geography, or size. What is the point of this study then, as related to the issues you raised in the Introduction?
l.77: You are at the same elevation as Hokkaido and you have very cold winters. Is it really tropical there?
l.84: Without explaining the symbols, equations are meaningless.
l.86: I checked the reference to find out about the fair profiles number but could not find an explanation. But I found an extensive modeling exercise with ECOMAG. To what extent does this paper repeat this reference?
l.91: The suction you apply in such instruments determines which part of the pore space you sample, but you do not report this.
Suction cups cannot sample macropores unless these remain filled for a long period of time, which is typically not the case in unsaturated soils. Did your soils have macropores?
Did you remove these during the winter? (I am not sure they survive when they freeze.)
l.96: ...Data quality control suggested next simulation periods... How exactly?
l.97, 98, 161, 181: unexplained abbreviations.
l.108-109: The end-member mixing analysis...hydrology methods... Unclear.
l.110: ... hereafter called fractions... A fraction is very different from a source. You need to explain better what exactly you are doing.
l.112: ...some empirical relations... Vague. And in the Introduction you stated that reliance on empirics was a weakness of current models.
l.123-124: ...water quality... I believe you mean the various substances dissolved in the water.
l.126-130: This explanation of the use of bivariate scatter plots needs to be explained much clearer. What property exactly are you plotting? Concentrations, fluxes, loads during a given period? And when you state all possible combinations need to be plotted a assume you mean all possible combinations of two, i.e., only solute pairs will be plotted.
What will be the effect on colinearity if one solute is non-sorbing and the other is adsorbed? Both can still be conservative.
l.179: Please consult the guidelines for authors on the use of abbreviations in equations and the font of variables.
Citation: https://doi.org/10.5194/hess-2021-626-RC1 -
AC1: 'Reply on RC1', Andrey Bugaets, 16 Mar 2022
The comment was uploaded in the form of a supplement: https://hess.copernicus.org/preprints/hess-2021-626/hess-2021-626-AC1-supplement.pdf
-
AC1: 'Reply on RC1', Andrey Bugaets, 16 Mar 2022
-
RC2: 'Comment on hess-2021-626', Anonymous Referee #2, 16 Feb 2022
This manuscript details a study that compares runoff decomposition as estimated by end-member mixing analysis on one hand and hydrological models on the other hand. This issue is clearly of great interest for both hydrological processes understanding and model development. At this stage, the paper has several shortcomings in terms of methods and data, which prevents a full understanding of the paper. My suggestion would be to be less ambitious, e.g. in the number of hydrological models used but more exhaustive in the details given throughout the manuscript. Additionally, it should be noted that the English level is pretty poor, I am not a native English speaker but I recommend that the authors proofread their revised manuscript before submission.
Major comments
- Lack of details
Throughout the paper, there is a lack of details. This affects both the data/method section and the results/discussion section at a level that precludes the reader to provide clear guidelines for further improvements. The required additional information is listed in the minor comments hereafter. The two other major comments are related to methodological issues.
- Hydrological model uncertainties and how the methodology of the paper reduces it
As explained in the introduction (l.31-39), hydrograph decomposition may be a powerful tool to reduce equifinality. In this sense, the present study shows relatively similar runoff simulations but with different flow components from hydrological models, but with different flow components. Unfortunately, the authors did not take this opportunity seriously, they used a single optimal parameter set for each model and did not discuss the impact of this choice, nor the way the parameter set is optimized. Consequently, it is pretty hard to conclude the relative weights of structural and parameter uncertainties in explaining the results.
- Short record periods
Only three years are available for model simulation (what about the warm-up year?). It is quite short and consequently, no validation was performed by the authors. Modeling results are presented only for calibration, which is problematic when dealing with parameter/structural uncertainties. Also, as low-flow components are extracted from hydrological models simulations, the authors should verify cautionly model initialization.
Minor (but still important) comments
l.77-78: not clear what is the time step of heavy rainfall and how extreme are these events.
l.79: not clear how averaging is performed, spatial or temporal?
Please add a table with both catchments characteristics (mean annual rainfall, temperature, runoff, land use lithology, topography, etc.). The differences in runoff yields for these two neighbor catchments are huge and I cannot figure out if it is due to lithological differences or specificity of the (short) record periods with extreme events.
Figure 1. Where the WMO station is located?
l.132: It is not clear how the end members are identified, what is the "independent information"?
Please add a table with the characteristics of the three hydrological models (with e.g. basis of the snow components, number of free parameters, spatial and temporal discretization, etc.). The information given for each model is not homogenous. Nothing is said on parameter estimation, which is in my opinion a key issue (see major comment #2).
l.238-249: Are the results are shown in calibration (and by the way, how the calibration is performed)?? Please modify Figure 5 so that the reader can see the whole record period simulation results.
Table 4: it appears that the models present quite different flow decompositions. Could this be due to the fact that the a priori three-component is wrong because too detailed for such small catchments? Since many flow decompositions only concern two flow components ("baseflow" and "surface flow"), did the authors challenge their prior 3-components hypothesis?
l.359-360: These perspectives are quite fuzzy. Please provide a real discussion section in the paper. There is a lot to say on both methodological limitations and further analysis of the results obtained.
Citation: https://doi.org/10.5194/hess-2021-626-RC2 -
AC2: 'Reply on RC2', Andrey Bugaets, 16 Mar 2022
The comment was uploaded in the form of a supplement: https://hess.copernicus.org/preprints/hess-2021-626/hess-2021-626-AC2-supplement.pdf
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