Groundwater Recharge Potential for Sustainable Water Use in Urban Areas of the Jequitiba River Basin, Brazil
and Fernando António Leal Pacheco 3,*Round 1
Reviewer 1 Report
Manuscript concerns issue of the spatialization of groundwater recharge potential for a sustainable water use in urban areas. The form of the manuscript is typical case study concerning the Jequitiba River basin in Brazil. The manuscript presents important topic, but it should be corrected according to the following remarks. The quality of the figure should be improved, the font size is too small: Line 257: Figure 11. Average and standard deviation of groundwater recharge potential of each soil use and cover class of the Jequitiba River basin, MG, Brazil. Add references to all equations, in the case You are not the Author. Article should be carefully edited according to Author’s guidelines, references, etc. Too little results and discussion of the performed calculations are performed. What period of observation does climatic data concern? Refer to assumed objectives in the conclusion. Line 242. It is a dot?(539 m³.ha–1.year–1). What are Your suggestions for good management practices for groundwater recharge? Readers are just informed about the obtained results. I recommend to describe obtained results in more precisely way, what would reinforce the considered problem.
Author Response
Ms. Ref. No.: sustainability-480808
Title: Spatialization of groundwater recharge potential for a sustainable water use in urban areas of the Jequitiba River basin in Brazil
Please see the yellow shaded lines in the revised manuscript, which describe the major changes to the original manuscript, requested by the reviewer(s).
Reviewer #1:
Manuscript concerns issue of the spatialization of groundwater recharge potential for a sustainable water use in urban areas. The form of the manuscript is typical case study concerning the Jequitiba River basin in Brazil. The manuscript presents important topic, but it should be corrected according to the following remarks.
We very much thank the comments and suggestions that were all welcome and thoroughly addressed. We did our utmost to comply with all requests with the purpose to improve the revised version.
The quality of the figure should be improved, the font size is too small: Line 257: Figure 11. Average and standard deviation of groundwater recharge potential of each soil use and cover class of the Jequitiba River basin, MG, Brazil.
Many thanks for the comment. We reviewed all figures for font size. Namely we eliminated the logos from maps because describing fonts are too small. We also moved references to coordination systems from the figure where the font was too small to the figure caption. Now the fonts in the figures are all visible. As regards the bar and line plots, we enlarged the entire figures that proportionally enlarged the font size making the text more visible. I hope you are satisfied with the result.
Add references to all equations, in the case You are not the Author.
The proper references were added close to each equation as requested.
Article should be carefully edited according to Author’s guidelines, references, etc.
The revised version was prepared according to the author’s guidelines, including references.
Too little results and discussion of the performed calculations are performed.
The presentation of results was extended to explain how base data were processed to calculate the recharge potential. The validation procedure is also better explained in the revised version. Besides the addition of new text, we also added a new table (new Table 2) to inform about the soil characteristics (porosity and hydraulic conductivity) used in Equation 2 to calculate the percolation factor. Moreover, a new figure (new Figure 9) was added to illustrate the validation method.
What period of observation does climatic data concern?
The period of observation is 2000 to 2018.
Refer to assumed objectives in the conclusion.
The conclusion section was re-written to comply with the request.
Line 242. It is a dot?(539 m³.ha–1.year–1).
The entire manuscript was revisited to check representation of units. The dots were removed.
What are Your suggestions for good management practices for groundwater recharge? Readers are just informed about the obtained results. I recommend to describe obtained results in more precisely way, what would reinforce the considered problem.
An entire new section was added to the revised manuscript where relevant management issues are discussed.
Author Response File: 
Author Response.docx
Reviewer 2 Report
This manuscript investigates the potential GW recharge in the Jequitiba River basin, Brazil. The argument is interesting but the paper suffers of lots of problems.
First of all, this argument is highly connected to the hydrogeological setting of the area.
Notwithstanding, the hydrogeology of this area is completely missing. The reader need information about the presence of aquifers, type and degree of permeability….All these data are absent, such as the presence of a piezometric map of the shallow aquifer. Moreover, I suppose that the area is caracterised by aquifer in fractured media, but the authors does not give any information about the fracturing degree. Hydrogeologists know that the recharge is highly influenced not only by lithology bur especially by fracturing degree. Thus, all the study results incomplete and inconsistent.
At last the results are foregone. It is known in literature that the predominant contribution to recharge is due to flat areas and forested regions and that urbanization reduces this phenomenon.
Indeed, also the authors report the same results in the introduction.
Bibliographic references about the analysis of the recharge could be very interesting in the state of the art, also with a brief discussion of advantages and disadvantages of different methods.
I suggest the following recent studies, for example:
· Blash & Bryson (2007) Distinguishing sources of ground water recharge by using δ2H and δ18O. Gr Water 45:294–308
· De Luca et al (2019). Potential recharge areas of deep aquifers: an application to the ercelli-Biella Plain (NW Italy). Rend. Fis. Acc. Lincei 30:137–153
· Ingram et al (2007) Noble gas excess air applied to distinguish groundwater recharge conditions. Environ Sci Technol 41(6):1949–1955
· Sukhija S, Reddy DV, Nagabhushanam P, Syed H, Giri VY, Patil DJ (1996) Environmental and injected tracers methodology to estimate direct precipitation recharge to a confined aquifer. J Hydrol 177:77–97
Some minor issues are reported in the following:
Line 106: it lacks the average yearly precipitation.
Fig 5 is redundand and foregone.
Line 192: it emerges a high percolation also in the cities, where I suppose a high pavimentation and cementification exists (see also lines 216-2017). It is a non-sense.
Fig 7: the different classes are not clearly identified.
Author Response
Ms. Ref. No.: sustainability-480808
Title: Spatialization of groundwater recharge potential for a sustainable water use in urban areas of the Jequitiba River basin in Brazil
Please see the yellow shaded lines in the revised manuscript, which describe the major changes to the original manuscript, requested by the reviewer(s).
Reviewer #2:
This manuscript investigates the potential GW recharge in the Jequitiba River basin, Brazil. The argument is interesting but the paper suffers of lots of problems.
First of all, this argument is highly connected to the hydrogeological setting of the area.
Notwithstanding, the hydrogeology of this area is completely missing. The reader need information about the presence of aquifers, type and degree of permeability….All these data are absent, such as the presence of a piezometric map of the shallow aquifer. Moreover, I suppose that the area is caracterised by aquifer in fractured media, but the authors does not give any information about the fracturing degree. Hydrogeologists know that the recharge is highly influenced not only by lithology bur especially by fracturing degree. Thus, all the study results incomplete and inconsistent.
Many thanks for sharing this pertinent concern. The study area section was extended to provide more or improved information about geology and hydrogeology. The types of aquifers were identified and related to the bearing rocks. Spatial relationships between lithologic types and soil types were also informed. Reported control of recharge by thick soil cover is also presented. The legend of geologic map was improved.
At last the results are foregone. It is known in literature that the predominant contribution to recharge is due to flat areas and forested regions and that urbanization reduces this phenomenon. Indeed, also the authors report the same results in the introduction.
Many thanks for this comment. Yes, the general relationship between recharge and factors such as topography, land use and urbanization are known. The purpose was not to present that as new outcome. The purpose was investigate the combined effect of all factors on recharge, which can only be accomplished when a spatially distributed model is used. In this context, forested areas may not be favorable for recharge if they are located where the migmatites outcrop. Because the combination of factors that influence recharge potential are numerous, a study of this kind is recommended to identify areas favorable for recharge considering all factors simultaneously.
Bibliographic references about the analysis of the recharge could be very interesting in the state of the art, also with a brief discussion of advantages and disadvantages of different methods. I suggest the following recent studies, for example:
· Blash & Bryson (2007) Distinguishing sources of ground water recharge by using δ2H and δ18O. Gr Water 45:294–308
· De Luca et al (2019). Potential recharge areas of deep aquifers: an application to the ercelli-Biella Plain (NW Italy). Rend. Fis. Acc. Lincei 30:137–153
· Ingram et al (2007) Noble gas excess air applied to distinguish groundwater recharge conditions. Environ Sci Technol 41(6):1949–1955
· Sukhija S, Reddy DV, Nagabhushanam P, Syed H, Giri VY, Patil DJ (1996) Environmental and injected tracers methodology to estimate direct precipitation recharge to a confined aquifer. J Hydrol 177:77–97
We thank the alert to refer the use of geochemical tracers in the estimation of groundwater recharge. These methods were missing in the state of the art description and are now acknowledged. The proposed studies were cited in the revised version and added to the reference list. We did not discussed potential advantages or disadvantages of the various methods because they are many and we believe the choice is more related to the objective and available data than with advantages or disadvantages.
Some minor issues are reported in the following:
Line 106: it lacks the average yearly precipitation.
We added the mean annual rainfall value and took the opportunity to provide information on mean temperatures that were also lacking.
Fig 5 is redundand and foregone.
Thanks for the comment. We replaced the figure by a technical workflow. We believe this new figure is much more interesting because it guides the reader through the model steps.
Line 192: it emerges a high percolation also in the cities, where I suppose a high pavimentation and cementification exists (see also lines 216-2017). It is a non-sense.
In fact the percolation factor in the urban area is overestimated. It was applied to the soil map. However, the impact on groundwater recharge potential is minimal because the high PF is largely compensated by the very low RF (»0) considering the adopted C values (»1). We clarified this issue in the revised version, as follows:
“The PF values are over estimated in the urban area of Sete Lagoas, because the figure does not account for the effects on PF caused by compaction and cementation. These overestimated PF values produce little impact on the recharge potential (see Figure 7) because the corresponding RF values are very low (» 0).”
Fig 7: the different classes are not clearly identified.
This caused by transparency that could ne be resolved in the revised version.
Author Response File: Author Response.docx
Reviewer 3 Report
The manuscript is well written and the authors should be appreciated. It is a hydrogeological characterization of a particular region aimed at sustainable water use management and therefore of a very descriptive nature. This manuscript presents an interesting study in this field and its findings might be useful to other studies aimed at similar topics. Some efforts are needed to enhance the description of the method and the analysis of results. I suggest a minor revision of this manuscript and expand my comments below.
Specific comments:
1. Suggest to change the title to be more concise ‘Groundwater recharge potential for sustainable water use in urban areas of the Jequitiba River basin, Brazil’
2. Validation of the method is not clear in the abstract
3. Multiple references are not of much use for a reader, as sometimes authors use them without studying all the references used. Each reference should be justified for its relevance to the manuscript and at least short assessment provided Eg. Line 46, 50, 51 etc.
4. Too many literature is quoted in the introduction. This can be reduced.
5. Authors can consider showing the world map in the inset figure in Figure 1
6. Avoid using ‘spatialized recharges’ and use ‘spatial variation in recharge’
7. Line 63, use ‘policy makers’ instead of politicians
8. Line 75-76. It is still unclear why demarking the groundwater potential zones is essential for the JRB. More information on the quantity of water withdrawn/ used in the region per year or the groundwater depletion levels between consecutive years can be provided to support the need for this work.
9. Line 79-83, how was the study validated?
10. Few figures can be combined such as Fig 2 and 3, Fig 9, 10 and 11
11. It would be easier for the readers to understand if the authors included a table indicating the layers used in the study, their source, resolution etc.
12. Title of figure 5 can be given as ‘Conceptual model for the estimation of groundwater recharge potential’
13. Figure 10 should be improved for clarity
14. There is very little in the discussion or conclusions that would put the results of this study in a broader context. The information obtained is exclusively limited to the study site, which may not be applicable to other sites because of different geological formation. A valid discussion which integrates the current study with the peer-reviewed literature is therefore required to ensure it is of wider applicability.
15. Suggest the authors to include the following related references:
Rajaveni, S.P., Brindha, K. and Elango, L. (2015) Geological and geomorphological controls on groundwater occurrence in a hard rock region. Applied Water Science, DOI 10.1007/s13201-015-0327-6
Dar IA, Sankar K, Dar MA (2011) Deciphering groundwater potential zones in hard rock terrain using geospatial technology. Environ Monit Assess 173(1–4):597–610
Author Response
Ms. Ref. No.: sustainability-480808
Title: Spatialization of groundwater recharge potential for a sustainable water use in urban areas of the Jequitiba River basin in Brazil
Please see the yellow shaded lines in the revised manuscript, which describe the major changes to the original manuscript, requested by the reviewer(s).
Reviewer #3:
The manuscript is well written and the authors should be appreciated. It is a hydrogeological characterization of a particular region aimed at sustainable water use management and therefore of a very descriptive nature. This manuscript presents an interesting study in this field and its findings might be useful to other studies aimed at similar topics. Some efforts are needed to enhance the description of the method and the analysis of results. I suggest a minor revision of this manuscript and expand my comments below.
We very much appreciate the time and effort put in the revision and the kind and motivating words about our manuscript. We improved various sections of the manuscript according to the comments and suggestions of other reviewers as well, especially the description of methods and results, namely through inclusion of a general workflow describing the modeling steps, a table with all data and their use in the model (as suggested below), among other things.
Specific comments:
1. Suggest to change the title to be more concise ‘Groundwater recharge potential for sustainable water use in urban areas of the Jequitiba River basin, Brazil’
We followed the suggestion.
2. Validation of the method is not clear in the abstract
We rephrased the following sentence to make it clear:
Where it was
The average results resembled the annual recharge calculated by a hydrograph method.
Now is
The average results resembled the annual recharge calculated by a hydrograph method, which worked as validation method.
3. Multiple references are not of much use for a reader, as sometimes authors use them without studying all the references used. Each reference should be justified for its relevance to the manuscript and at least short assessment provided Eg. Line 46, 50, 51 etc.
4. Too many literature is quoted in the introduction. This can be reduced.
We just wanted to give credit to various works relevant for the state of the art, which is fair. Therefore, we keep the reference issue unaltered. In fact is the only suggestion we did not follow.
5. Authors can consider showing the world map in the inset figure in Figure
Well, Brazil is a regional readily identified region. We did not show the world map but reorganized the figure and merged it with figures 2, 3 and 4 as suggested in a comment below.
6. Avoid using ‘spatialized recharges’ and use ‘spatial variation in recharge’
We followed the suggestion and replaced “spatialized recharges” by “spatial variation of recharge” throughout the text, where applicable
7. Line 63, use ‘policy makers’ instead of politicians
We replaced “politicians” by “policy makers” as suggested
8. Line 75-76. It is still unclear why demarking the groundwater potential zones is essential for the JRB. More information on the quantity of water withdrawn/ used in the region per year or the groundwater depletion levels between consecutive years can be provided to support the need for this work.
Many thanks for this pertinent comment. In the revised version we provided more detailed information on the use of catchment groundwater, namely in the most densely populated town of Sete Lagoas, which triggered the development of this study at catchment scale. Specifically, we added the following paragraph:
“Significant amounts of groundwater are withdrawn from the Jequitiba river basin, because this catchment is located in a populous region of Minas Gerais State, which hosts a large population and several industries from different segments [72]. According to Pessoa [73], in 1993 the water for domestic use in the largest town in the basin (Sete Lagoas, representing 94.3% of the entire population) was supplied by groundwater resources, namely 65 drilled wells with an average yield of 8.0 L s–1 (520 L s–1 of total yield). In those days, the population of Sete Lagoas was nearly 150 000 and consumed approximately 200 L habitant–1 day–1. Thus, the pressure over the drilled wells was evaluated in 16h of pumping every day and considered preoccupying. Besides, the quality of these resources was threatened because the domestic sewage system was lacking. The situation of Sete Lagoas was re-evaluated in 2008 by Botelho [74], with similar conclusions. Twenty five years after the evaluation of Pessoa, the number of drilled wells raised from 65 to 94 (44% increase), keeping a similar average yield (7.8 L s–1), while the population of Sete Lagoas raised from 150 000 to 220 000 (47% increase). The sewage system was still lacking or incomplete. The study of Botelho also refers the occurrence of subsidence events in Sete Lagoas, which sharply increased from 1 event in 1980 to 7 events in 2000. The relationship with excessive groundwater abstraction was suggested. Moreover, the results of interviews to SAAE (Autonomous Service of Water and Sewage) employees refer that “…as the urban space expands, the municipal authorities do not improve the supply and distribution systems, and do not prioritize studies and planning for the occupation of space…”. It is therefore urgent to help the municipality accomplishing the task, through provision of relevant information and data for planning such as the spatial distribution of groundwater recharge potential.”
9. Line 79-83, how was the study validated?
We added a fourth specific objective to refer the validation step, as follows:
“d) validate the model through calculation of groundwater recharge using an independent approach based on independent data, namely stream flow recession analysis.”
10. Few figures can be combined such as Fig 2 and 3, Fig 9, 10 and 11
We merged Figures 1, 2, 3 and 4 into a single figure (new figure 1, a, b, c and d) and figures 9, 10 and 11 as table 5.
11. It would be easier for the readers to understand if the authors included a table indicating the layers used in the study, their source, resolution etc.
We followed the suggestion. Now, the new table 1 describes the layers and specific uses in the study, their sources, etc.
12. Title of figure 5 can be given as ‘Conceptual model for the estimation of groundwater recharge potential’
Former Figure 5 (new Figure 2) was replaced by a technical workflow, which we found more necessary than a conceptual model. We follow your suggestion as regards the title, but replacing the word “conceptual mode” by “workflow”. Then, the title of Figure 2 is now “Figure 2. Workflow for the estimation of groundwater recharge potential.”
13. Figure 10 should be improved for clarity
Figure 10 was converted into a table in the revised version
14. There is very little in the discussion or conclusions that would put the results of this study in a broader context. The information obtained is exclusively limited to the study site, which may not be applicable to other sites because of different geological formation. A valid discussion which integrates the current study with the peer-reviewed literature is therefore required to ensure it is of wider applicability.
15. Suggest the authors to include the following related references:
Rajaveni, S.P., Brindha, K. and Elango, L. (2015) Geological and geomorphological controls on groundwater occurrence in a hard rock region. Applied Water Science, DOI 10.1007/s13201-015-0327-6
Dar IA, Sankar K, Dar MA (2011) Deciphering groundwater potential zones in hard rock terrain using geospatial technology. Environ Monit Assess 173(1–4):597–610
We added a new section called “Controls of groundwater recharge” where the requested discussion is made. We also used the suggested references (among others) in that new section
Author Response File: Author Response.docx
Reviewer 4 Report
The paper deals with the problem of aquifer recharges in complex areas. The paper need improvements especially for clarifying some aspects to the readers.
First the authors should stress more why can be useful the proposed approach for the management of the territory.
A second question concern the number of years used for the application, 18 years, it was not possible to use more years? It is known that in these last years we are facing a general change in the precipitation intensity and frequency, for the recharge of so large aquifers may be it is more stable to use more years.
There are small errors in the text (i.e. parameter C table 3, it seems to me that is table 2)
I don't find clear the validation procedure, I think the authors should clarify it.
Some conclusions are well known (flat areas, forests etc.) may be the authors could enhance other aspects more interesting like the use from authority of the procedure.
I am not sure that urbanized areas, especially those with a low wastewater treatment level, in terms of territory and efficiency, should be considered a suitable area for the recharge, in fact the authors affirm that the sewage systems can produce contamination of the groundwaters, it could be more useful to neglect completely the urbanized areas which furthermore presents great difficulties for the runoff management ?
Author Response
Ms. Ref. No.: sustainability-480808
Title: Spatialization of groundwater recharge potential for a sustainable water use in urban areas of the Jequitiba River basin in Brazil
Reviewer #4:
The paper deals with the problem of aquifer recharges in complex areas. The paper need improvements especially for clarifying some aspects to the readers.
First the authors should stress more why can be useful the proposed approach for the management of the territory.
Answer:
An entire new section was added to the revised version addressing management considerations. Please see Section 4.3 – Management considerations
A second question concern the number of years used for the application, 18 years, it was not possible to use more years? It is known that in these last years we are facing a general change in the precipitation intensity and frequency, for the recharge of so large aquifers may be it is more stable to use more years.
Answer:
We agree, however we did not have longer series. In the revised version we added the following sentence to alert for the situation:
“Longer time series would be more adequate for recharge estimation in a changing climate, but they were not available.”
There are small errors in the text (i.e. parameter C table 3, it seems to me that is table 2).
Answer:
The entire text was thoroughly revised to identify and correct small errors. The aforementioned error was corrected.
I don't find clear the validation procedure, I think the authors should clarify it.
Answer:
In the revised version we added a new figure and new text to exemplify how the validation procedure works. In general, validation was based on the calculation of recharge using an independent well-known method, and subsequent comparison of results among the proposed and the well-known method.
Some conclusions are well known (flat areas, forests etc.) may be the authors could enhance other aspects more interesting like the use from authority of the procedure.
Answer:
A new section 5 – Conclusions was added to the revised version where specific outcomes from application of our method were highlighted.
I am not sure that urbanized areas, especially those with a low wastewater treatment level, in terms of territory and efficiency, should be considered a suitable area for the recharge, in fact the authors affirm that the sewage systems can produce contamination of the groundwaters, it could be more useful to neglect completely the urbanized areas which furthermore presents great difficulties for the runoff management ?
Answer:
We agree. In the revised version (new section 4.3) we alerted for that situation.
Author Response File: 
Author Response.pdf
Round 2
Reviewer 1 Report
My numerous remarks were included in the text. The quality of the figures could be better.
Author Response
Dear reviewer,
many thanks for your recognition of our efforts.
Kind regards
Reviewer 2 Report
The paper can be accepted in this form
Author Response
Dear reviewer,
many thanks for your decision
Kind regards
