Incorporating Advanced Scatterometer Surface and Root Zone Soil Moisture Products into the Calibration of a Conceptual Semi-Distributed Hydrological Model

Round 1

Reviewer 1 Report

In the paper is showed how satelitte product like ASCAT can be used to improving calibration of hydrological model. Based on the  ASCAT data  the surface soil moisture and root zone soil moisture indexes were used to calibration of the hydrological model. The analysis was performed in 209 catchments divided on Lowland and Alpine  in Austria. The paper is potentiall interesting to readers and has innovative aspect linking modern measuring techniques with modelling of hydrologial processes. The paper is well writting, has logical structure. I recommend to accept the paper after improvment discussion section.  
1. L 349-350 What is reason overestimated the runoff in loweland catchments? Errors in evaporation?
2. Chapter 4.1 and 4.2. I suggest showing flow duration curves for measured and calculated discharges for all variants. I think that the cuvres can show what model assesment high, median and low flows. It would be helpful in discussion 
3. L 498-500 Why in higher fores cover catchments were worser results? Does evaporation plays important role? 
4 L 564-565:How uncertainty was calculated? Mayby it will be worth to use some measurte of uncertainty like Average Relative Length, Average Asymmetry Degree or Average Deviation Amplitude to show the uncertainty? Yo ucan see following paper: Xiong, L.H., Wan, M., Wei, X.J., 2009. Indices for assessing the prediction bounds of hydrological models and application by generalized likelihood uncertainty estimation. Hydrological Sciences Journal. 54, 852–871.

Author Response

Dear Editor,

Please find below our reply to the Reviewers comments and recommendations. We have inserted the corrections in the new text, using track changes.

The text was also rephrased/rewritten according to your suggestion due to the duplicate check. Some of the words in the duplicate check are standard terms or common words used in engineering hydrology. These were not replaced but have been kept in the usual form.

Because of the multiple changes due to duplicate checks, for a better understanding, we upload the text with the "track changes" and we also put the text with accepted ("track changes") in the same doc. (water-1439017_track and clear). The clear text with accepted "track changes" starts from the page: 26.

 

 

Dear Sir/Madam,

 

We want to thank all reviewers for their feedback. At the same time, we would like to appreciate constructive and inspiring comments and recommendations based on which we improved our manuscript. We thoroughly went through the entire manuscript and made an effort to re-elaborate the parts that had been pointed out. We found it appropriate to respond to each of the comments individually. The comments have been sorted into the following groups:  Reviewer 1, Reviewer 2.

 

REVIEWER 1:

In the paper is showed how satellite product like ASCAT can be used to improving calibration of hydrological model. Based on the ASCAT data the surface soil moisture and root zone soil moisture indexes were used to calibration of the hydrological model. The analysis was performed in 209 catchments divided on Lowland and Alpine in Austria. The paper is potential interesting to readers and has innovative aspect linking modern measuring techniques with modelling of hydrological processes. The paper is well writing, has logical structure. I recommend to accept the paper after improvement discussion section.  

 

Dear Reviewer, thank you for your constructive and inspiring comments and recommendations.

We have accepted the improvement of the discussion section, and we have separated the Conclusions into Conclusions and Discussion parts. The division into these parts was done as follows:

Discussion part lines 473-511, 516-528, 538-561.

Conclusion part lines 466-472, 512-515, 528-537 and 562-567.

The text of the Conclusions and Discussion part was also slightly rewritten according to the Reviewer´s #2 and editor´s recommendations.

 

1. L 349-350 What is reason overestimated the runoff in lowland catchments? Errors in evaporation?
   
   

Thank you for the comment. We did not include the volume error in the target function during calibration. The value of volume error is small, 2%-3%, which confirms a good quality of the semi-distributed model calibration. The slight overestimation can be observed only in the calibration period, while in the validation period, the lowland and Alpine catchments have similar performance due to the estimated volume error.

 

2. Chapter 4.1 and 4.2. I suggest showing flow duration curves for measured and calculated discharges for all variants. I think that the curves can show what model assessment high, median and low flows. It would be helpful in discussion 
   
   

Thank you for the comment. The analysis of flow duration curves was not done in our study. The aim of the study was not in comparison of flow duration curves for measured and calculated discharges. Still, we have been looking for a comparison of the improvement of calibration using objective functions.

3. L 498-500 Why in higher forest cover catchments were worse results? Does evaporation plays important role? 

Thank you for the comment. The ASCAT data do not perform well in the areas with higher forest coverage, where the reason for the low quality of satelite soil moisture products is dense vegetation. This finding could also be found in other studies,  see e.g. (Brocca,et al., 2012, 2017; Xu et al., 2014).

Brocca, L.; Moramarco, T.; Melone, F.; Wagner, W.; Hasenauer, S.; Hahn, S. Assimilation of Surface- and Root-Zone ASCAT Soil Moisture Products Into Rainfall–Runoff Modeling. In IEEE Trans. Geosci. Remote Sensing 50 (7), 2012, pp. 2542–2555. DOI: 10.1109/TGRS.2011.2177468.

Brocca, Luca; Ciabatta, Luca; Massari, Christian; Camici, Stefania; Tarpanelli, Angelica: Soil Moisture for Hydrological Applications: Open Questions and New Opportunities. In Water 9 (2), 2017, p. 140. DOI: 10.3390/w9020140.

Xu, X.; Li, J.; Tolson, B.A. Progress in integrating remote sensing data and hydrologic modeling. Progress in Physical Geography, 2014, Vol. 38(4) 464–498, DOI: 10.1177/0309133314536583.

 

 

4 L 564-565: How uncertainty was calculated? Mayby it will be worth to use some measure of uncertainty like Average Relative Length, Average Asymmetry Degree or Average Deviation Amplitude to show the uncertainty? You can see following paper: Xiong, L.H., Wan, M., Wei, X.J., 2009. Indices for assessing the prediction bounds of hydrological models and application by generalized likelihood uncertainty estimation. Hydrological Sciences Journal. 54, 852–871.

 

Thank you for the comment. We have deleted this general statement from the text.

In our study we have not statistically analysed the uncertainty. The quality and model performance was estimated using objective function and correlation coefficients.

Author Response File: Author Response.docx

Reviewer 2 Report

Dear authors, I have carefully reviewed your paper and consider that it is very interesting and the results, as a model, very accurate. I consider that the introduction is too long and then, the discussion must be separated from the conclusions. The discussion is too short with no comparisons with other studies. I miss any map showing the spatial differences among catchments. Also, a digital elevation model and land use map to verify which catchment and due to which land use is affecting these changes. See more comments in my attached pdf.

Comments for author File: Comments.pdf

Author Response

Dear Editor,

Please find below our reply to the Reviewers comments and recommendations. We have inserted the corrections in the new text, using track changes.

The text was also rephrased/rewritten according to your suggestion due to the duplicate check. Some of the words in the duplicate check are standard terms or common words used in engineering hydrology. These were not replaced but have been kept in the usual form.

 Because of the multiple changes due to duplicate checks, for a better understanding, we upload the text with the "track changes" and we also put the text with accepted ("track changes") in the same doc. (water-1439017_track and clear). The clear text with accepted "track changes" starts from the page: 26.

 

Dear Sir/Madam,

 

We want to thank all reviewers for their feedback. At the same time, we would like to appreciate constructive and inspiring comments and recommendations based on which we improved our manuscript. We thoroughly went through the entire manuscript and made an effort to re-elaborate the parts that had been pointed out. We found it appropriate to respond to each of the comments individually. The comments have been sorted into the following groups:  Reviewer 1, Reviewer 2.

 

REVIEWER 2:

 

Dear authors, I have carefully reviewed your paper and consider that it is very interesting and the results, as a model, very accurate. I consider that the introduction is too long and then, the discussion must be separated from the conclusions. The discussion is too short with no comparisons with other studies. I miss any map showing the spatial differences among catchments. Also, a digital elevation model and land use map to verify which catchment and due to which land use is affecting these changes. See more comments in my attached pdf.

 

Dear reviewer, thank you for your constructive and inspiring comments and recommendations.

The comments from the pdf version of our paper and our answers are summarised in the following text.

Line 2 -meaning?

Accepted, we have rewritten the title of the study to “Incorporating Advanced Scatterometer surface and root zone soil moisture products into the calibration of a conceptual semi-distributed hydrological model”

Line 14 - why is this necessary?

We added the following explanation in the Abstract:

The role of soil moisture is widely accepted as a significant factor in the mass and energy balance of catchments and as a controller in surface and subsurface runoff generation.

Line: 23 - please, add any numerical result

Accepted: we added the numerical results of the improved catchments.

“The combined use of soil moisture and discharges in the calibration improved the soil moisture simulation in more than 73 % of the catchments, except for the catchments with higher forest cover percentages. Improvements also occurred in the runoff model efficiency, in more than 27 % of the catchments, mostly in the watersheds with a lower mean elevation and a higher proportion of farming landuse, as well as in the alpine catchments where the runoff is not significantly influenced by snowmelt and glacier runoff.”  

Line: 31 - only in Austria?

This was a general statement and was deleted from the text.

As it is written in lines 30-31: “The improved model efficiency and reduction of parameter uncertainties have important implications for water resource management purposes.” 

We wanted to state that the findings are valid not only in Austria, but also in other regions.

Line: 34 you should think about including more powerful keywords

Accepted, keywords were replaced to:

Advanced Scatterometer, semi-distributed hydrological model, surface and root zone soil moisture, multi-objective calibration

Line: 37- 41 - add references or eliminate this general part

Accepted, this part of Introduction was deleted.

Line 52: mentioned in previous reviews? or is it new?

 

Our study examined the potential of new satellite datasets of soil moisture (ASCAT) for multiple objective calibrations of a dual-layer, using a conceptual, semi-distributed hydrological model. This is a novelty to other studies.

Line 83: try to start different. I think that mdpi guideliness needs to include the name of the author

Accepted, we include the name of the cited study authors as:

Line 75: In paper Parajka et al. [25]

Line 83: In Wander et al. paper [26]

Line 99: In Li et al. paper [29]

Line 108: In Tong et al. paper [12] 

 

Line 99: -I would reduce the number of examples and could be used for the discussion

Accepted, lines 77-112 from Introduction were removed to the Discussion part.

 

Line 153-158:  not necessary this paragraph

Accepted, lines 153-158 were deleted from the text.

Line 163: I would include the name of the biggest and the smallest ones.

Accepted, we have added the names of the gauging stations: The catchments’ areas vary between 13.7 (Micheldorf, River-Krems) to 6214 km² (Bruck an der Mur unter Muerz, River-Mur) with a median of 167.3 km²

 

Line 168: - add the north and grid of coordinates to locate this properly rivers? source?

Accepted, we have added the north and the grid of coordinates in Figure 1.

 

Line 173: source?

Accepted, we have added a reference to this paper:

Tong, R.; Parajka, J.; Salentinig, A.; Pfeil, I.; Komma, J.; Széles, B. et al.: The value of ASCAT soil moisture and MODIS snow cover data for calibrating a conceptual hydrologic model. In Hydrol. Earth Syst. Sci. 25 (3), 2021, pp. 1389–1410. DOI: 10.5194/hess-25-1389-2021.

 

Line 176: years? did you correct the categories?

We have inserted the citation of CORINE (2006) and added this information also in the text.

 

Line 179: obtained

Accepted we have changed the word to “obtained”.

 

Line 187: years?

We added also the year when the soil data were processed (2018)

Fig. 6: please, add the axis

Accepted, we have added the description of the axis in the Figure 6.

 

Line 465: Separate these parts and include references as you did in the intro

Accepted, we have separated the Conclusions and the Discussion parts and included the appropriate references, too.

The division into these parts was done as follows:

Discussion part lines 473-511, 516-528, 538-561.

Conclusion part lines 466-472, 512-515, 528-537 and 562-567.

The text of Conclusions and Discussion part was also rewritten.

From the Introduction, lines 77-112 were also removed to the Discussion part, as proposed by the Reviewer.

Comments and suggestion for Authors:

I miss any map showing the spatial differences among catchments. Also, a digital elevation model and land use map to verify which catchments and due to which land use is affecting these changes:

We added a new table (Table 9.) in the Results section as also comment to the results. The table represents the selected catchment´s characteristics you mentioned and numbers of the catchments in the case of improvement in RME, root-soil moisture correlation, and skin-soil moisture correlation.

 

„From the results in Table 9, it is seen that the assimilation of the SWI in the model calibration improved the RMEs in the catchments with a lower mean catchment elevation (the median of MELE ranges from 738.5 to 754.9 m a.s.l), a lower mean slope of the terrain (the median of SL ranges from 10.44 to 12.43 %), and with a higher percentage of agricultural land (the median of AP ranges from 26.8 to 38.1 %). On contrary, the improvements were not indicated in the catchments with a higher mean catchment elevation (the median of MELE ranges from 1270.9 to 1335.4 m a.s.l), a higher mean slope of the terrain (the median of SL ranges from 23.61 to 24.73 %) and a lower percentage of agricultural land (the median of AP ranges from 10.9 to 11.4 %). An improvement in the values of RME only slightly depends on the percentage of forest coverage. The percentage of forest cover and the percentage of agricultural land play an essential role in the improvement of the soil moisture simulations. The values of R SR were improved in the catchments with a lower mean slope of the terrain (the median of SL ranges from 16.06 to 18.54 %), a lower percentage of forest coverage (the median of FP ranges from 45.3 to 46.3 %) and with a higher percentage of agricultural land (the median of FP ranges from 18.2 to 20.1 %). The improvement of R SR was not indicated in the catchments with a higher mean slope of the terrain (the median of SL ranges from 23.4 to 24.7 %), a higher percentage of forest coverage (the median of FP ranges from 63.1 to 78.4 %) and with a lower percentage of agricultural land (the median of FP ranges from 5.9 to 8.0 %). The similar results we also indicated in the improvements in the values of R SS.”

Author Response File: Author Response.docx