Structural Classification, Discharge Statistics, and Recession Analysis from the Springs of the Gran Sasso (Italy) Carbonate Aquifer; Comparison with Selected Analogues Worldwide

Round 1

Reviewer 1 Report

Dear authors,

I read this article with great interest. This study examines the relative importance of karst conduits and fractures in driving groundwater flow and how it affects the discharge of springs and the long-term availability of water resources. The authors applied statistics to the hydrographs of the discharge and studied the recessions to provide information on the reliability, variability, and flow regime of six springs at the Gran Sasso aquifer in Central Italy. They found that joints and bedding plane fractures dominate the groundwater flow, which fits the relative steadiness of the discharges and the pattern of the Flow Duration Curves. The proposed approach has a wider significance that it can help identify and manage groundwater resources in areas with complex geological structures, which is important for ensuring the long-term availability of water resources. The approach can also be applied in other regions with similar geological settings to better understand and manage groundwater flow, which is crucial for sustainable water resource management. The manuscript is clearly written and informative, but some details need to be revised before publication.

Specific comments for revision are given as follows:

Major comments:

1. Please carefully check the abbreviations in the figures and main body text. Keep the abbreviations consistent everywhere.

2. Too much blank space in Tables 2 and 3 takes. I suggest combining these tables or rearranging them for a better presentation.

3. The paper discusses multiple statistical parameters but does not clearly explain how these parameters are related to each other. It is recommended that the authors elaborate on the relationships between these statistical parameters and explain their specific roles in the study.

4. The article mentions the limitations of traditional karst hydrology methods (e.g., Maillet formula) when applied to non-highly karstified systems. It is suggested that the authors discuss other potential hydrology methods that may be suitable for this situation and explain why these methods may be more suitable for the characteristics of the study area.

 

Minor comments:

1. Fig. 1: Please keep the spellings of Tyrrhenian Sea consistent in the subfigures.

2. Fig. 3 caption, line 182: Is U6 a typo of C6 in Fig. 3(1)?

3. I would strongly suggest the authors clarify the difference between the discharge reliability and variability indicated by the Iv index. From Table 3, reliability and variability seem to be expressed based on two different classification schemes of the single indicator, Iv.

4. Page 9, lines 252–253: The first letter of “exceeded” does not need to be capitalized.

5. Page 10, line 164: change “location” to “locations.”

6. Page 10, Fig.5: The hydrostratigraphic complexes in Fig. 5 are pretty illustrated. However, I find that the legends do not correspond to the colors on the map, and the abbreviations of the springs seem to be inconsistent with Table 4.

7. Please align the numbers and texts in the tables.

8. Please keep the formula centered and the numbering aligned to the right.

9. I would suggest putting Table 3 ahead of Table 2, as Iv was introduced before SVC and SVCP.

10. The degrees of V could also be listed in a table as Iv, SVC, and SVCP.

11. Page 16, Fig. 7, and Table 5: Fig. 7 shows the α value for the combined recession of MT is 0.05, while this value is 0.001 in Table 5. Please carefully inspect the statistics.

12. Page 19, lines 522–523: what does “[sensu 57]” mean? This might be an in-text citation error.

Minor editing of English language required.

Author Response

Reply to Reviewer 1

Dear authors,

I read this article with great interest. This study examines the relative importance of karst conduits and fractures in driving groundwater flow and how it affects the discharge of springs and the long-term availability of water resources. The authors applied statistics to the hydrographs of the discharge and studied the recessions to provide information on the reliability, variability, and flow regime of six springs at the Gran Sasso aquifer in Central Italy. They found that joints and bedding plane fractures dominate the groundwater flow, which fits the relative steadiness of the discharges and the pattern of the Flow Duration Curves. The proposed approach has a wider significance that it can help identify and manage groundwater resources in areas with complex geological structures, which is important for ensuring the long-term availability of water resources. The approach can also be applied in other regions with similar geological settings to better understand and manage groundwater flow, which is crucial for sustainable water resource management. The manuscript is clearly written and informative, but some details need to be revised before publication.

Specific comments for revision are given as follows:

Major comments:

1. Please carefully check the abbreviations in the figures and main body text. Keep the abbreviations consistent everywhere.

Reply: We found mistakes on the abbreviations in the text (page 7, first lines paragraph 3) and in Figure 4, and all the corrections have now been applied.

2. Too much blank space in Tables 2 and 3 takes. I suggest combining these tables or rearranging them for a better presentation.

Reply: Size of Tables 2 and 3 has been reduced to delete blank spaces to address the comment of the reviewer

3. The paper discusses multiple statistical parameters but does not clearly explain how these parameters are related to each other. It is recommended that the authors elaborate on the relationships between these statistical parameters and explain their specific roles in the study.

Reply: Several lines of text have been added in the new version to highlight the relationship between the parameters (pages 9 and 10, subparagraph 3.2; “of note...efforts”)

4. The article mentions the limitations of traditional karst hydrology methods (e.g., Maillet formula) when applied to non-highly karstified systems. It is suggested that the authors discuss other potential hydrology methods that may be suitable for this situation and explain why these methods may be more suitable for the characteristics of the study area.

Reply: The discussion has been implemented to address future research on hydrogeological modelling. The proposed methods have been designed to be specific for the study site characteristics (page 19, subparagraph 5.2; “as a consequence...study site”)

 

Minor comments:

1. Fig. 1: Please keep the spellings of Tyrrhenian Sea consistent in the subfigures.

Reply: Correction applied to Figure 1 as requested by the reviewer

2. Fig. 3 caption, line 182: Is U6 a typo of C6 in Fig. 3(1)?

Reply: Yes, there was a mistake in the caption of Figure 3a (page 7). Correction applied under request of the reviewer

3. I would strongly suggest the authors clarify the difference between the discharge reliability and variability indicated by the Iv index. From Table 3, reliability and variability seem to be expressed based on two different classification schemes of the single indicator, Iv.

Reply: Clarification on Iv made in the subparagraph 3.2 (page 9, see “of note...stable”)

4. Page 9, lines 252–253: The first letter of “exceeded” does not need to be capitalized.

Reply: Correction made as requested by the reviewer (page 10, see subparagraph 3.2, “discharge value that is exceeded in 10%”)

5. Page 10, line 164: change “location” to “locations.”

Reply: Correction made in the subparagraph 4.3 (page 16, see  “locations of Mount Vettore and Piobbico in Figure 1b”)

6. Page 10, Fig.5: The hydrostratigraphic complexes in Fig. 5 are pretty illustrated. However, I find that the legends do not correspond to the colors on the map, and the abbreviations of the springs seem to be inconsistent with Table 4.

Reply: There was no match in colour for the Complex 2 in Figure 5, we have applied a correction to the figure. We have also fixed the issues on the legends of Figure 5 and Table 4 finding mistakes on the abbreviation of Mortaio d’Angri (MA), and Vitella d’Oro (VO)

7. Please align the numbers and texts in the tables.

Reply: Correction made as requested by the reviewer in the new Table 3

8. Please keep the formula centered and the numbering aligned to the right.

Reply: Correction made as requested by the reviewer (page 10, see formula 1 in subparagraph 3.2)

9. I would suggest putting Table 3 ahead of Table 2, as Iv was introduced before SVC and SVCP.

Reply: We have inverted Tables 2 and 3 with respect to the previous version under the observation of the reviewer

10. The degrees of V could also be listed in a table as Iv, SVC, and SVCP.

Reply: V values has now been inserted in Table 3 as requested by the reviewer

11. Page 16, Fig. 7, and Table 5: Fig. 7 shows the α value for the combined recession of MT is 0.05, while this value is 0.001 in Table 5. Please carefully inspect the statistics.

Reply: The correct value for α is 0.001, we have applied the correction to Figure 7

12. Page 19, lines 522–523: what does mean? This might be an in-text citation error.

Reply: The spring is related to a tunnel that intercepts a normal fault characterized by high storage coefficient and transmissivity. The text was reorganized under request of the reviewer, and a reference has been added to address the reader towards further detail (page 18, subparagraph 5.1, “water table was...storage coefficient”)

 

Reviewer 2 Report

This study investigated the discharge regime of the springs at the Gran Sasso from conceptual and mathematical perspectives. Corresponding conclusions are useful to understand the role of karst conduits and fractures in driving groundwater flow. The sections 3 (Methods) and 6 (Conclusion) should be concise and comprehensive to highlight the key information which is useful for this manuscript. Overall, I recommend this MS to be published after a minor revision.

none

Author Response

Reply to Reviewer 2

 

This study investigated the discharge regime of the springs at the Gran Sasso from conceptual and mathematical perspectives. Corresponding conclusions are useful to understand the role of karst conduits and fractures in driving groundwater flow. The sections 3 (Methods) and 6 (Conclusion) should be concise and comprehensive to highlight the key information which is useful for this manuscript. Overall, I recommend this MS to be published after a minor revision.

Reply: Thank you for the positive feedback. Several lines of text have been added to the section 3 (pages 9 and 10; sub-paragraph 3.2) to (i) make the manuscript more comprehensive, and (ii) cover the comments of Reviewer 1, 2 and 3.

Redundant words (robust, intercepted by a tunnel, and northern) have been deleted from the Conclusion to make the section 6 (pages 21-22) more concise as requested by the reviewer.

Reviewer 3 Report

General comment:

The manuscript deals with assessments on springs of the Gran Sasso carbonate aquifer. A statistical approach to the hydrographs of the discharge was applied and the recessions was studied to provide information on the degree of reliability, and variability of the springs.

The manuscript is suitable to be published in this journal, however some points should be addressed before publication.

Some minor language mistakes are present that should anyway be corrected.

 

1. Introduction

Groundwater protection from pollution is a fundamental topic and I suggest to include it into the introduction.  Please, consider the following papers:

o   An innovative in-situ DRAINage system for advanced groundwater reactive TREATment (in-DRAIN-TREAT) (2021) Chemosphere, 270, art. no. 129412

o   Remediation technologies for contaminated groundwater due to arsenic (As), mercury (Hg), and/or fluoride (F): A critical review and way forward to contribute to carbon neutrality (2023) Separation and Purification Technology, 314, art. no. 123474

o   Effects of functional group loss on biochar activated persulfate in-situ remediation of phenol pollution in groundwater and its countermeasures (2023) Journal of Environmental Management, 341, art. no. 118076

Please, better highlight the novelty of this research.

3. Methods

Please, specify the feasibility and accuracy of the methods used.

Please, clarify if the quality of the water was investigated.

Please, clarify if chemical analysis on water composition were carried out, focusing on ion composition.

4. Results

Water quality measurement should be included.

The attenuation capacity of the groundwater should be considered.

5. Discussion

 

Please, improve comparison with literature findings.

Author Response

Reply to Reviewer 3

 

General comment:

The manuscript deals with assessments on springs of the Gran Sasso carbonate aquifer. A statistical approach to the hydrographs of the discharge was applied and the recessions was studied to provide information on the degree of reliability, and variability of the springs. The manuscript is suitable to be published in this journal, however some points should be addressed before publication.

Reply: Thank you for the interesting comments, and the suggested references that have been inserted

 

Some minor language mistakes are present that should anyway be corrected.

Reply: The language have been revised under request of the reviewer. See all the corrections in red color to the sub-paragraphs 2.1 and 2.2

 

1. Introduction

Groundwater protection from pollution is a fundamental topic and I suggest to include it into the introduction.  Please, consider the following papers:

- An innovative in-situ DRAINage system for advanced groundwater reactive TREATment (in-DRAIN-TREAT) (2021) Chemosphere, 270, art. no. 129412

- Remediation technologies for contaminated groundwater due to arsenic (As), mercury (Hg), and/or fluoride (F): A critical review and way forward to contribute to carbon neutrality (2023) Separation and Purification Technology, 314, art. no. 123474

- Effects of functional group loss on biochar activated persulfate in-situ remediation of phenol pollution in groundwater and its countermeasures (2023) Journal of Environmental Management, 341, art. no. 118076

Reply: We agree with the reviewer that groundwater protection from pollutants is an important topic. We have inserted all the three references on contaminant transport and remediation in the subparagraph 5.2 to highlight the importance of groundwater protection from pollution (page 19, “As a consequence…worldwide”)

 

Please, better highlight the novelty of this research.

Reply: We now clearly state and highlight the novelty of this research as requested by the reviewer. See new version of the introduction (page 2, “a study of the structural geology...previous literature”).

 

3. Methods

Please, specify the feasibility and accuracy of the methods used.

Reply: Detail on the feasibility and accuracy of the methods used has been added in the new version of the subparagraph 3.2 (pages 9, 10, “of note, the degrees…computational efforts”)

 

Please, clarify if the quality of the water was investigated.

Reply: Hydrochemistry and water qualities are outside the scope of this paper that focus on the physical hydrogeology. Our research colleagues have already published water quality analyses in three papers from the same study site and springs (Barbieri et al. 2005 Appl Geochem; Falcone et al. 2008 J Hydrol; Lorenzi et al. 2023 Env Earth Sci). We now summarized water quality data on the subparagraph 2.2. in the hydrogeological setting (page 6, hydrochemistry…according to)

 

Please, clarify if chemical analysis on water composition were carried out, focusing on ion composition.

Reply: Ion composition has been analysed and published by our research colleagues in one manuscript (Falcone et al. 2008 J. Hydrol). We have now reported the results in the subparagraph 2.2 (page 6, hydrochemistry…according to)

 

4. Results

Water quality measurement should be included.

Reply: Results from major ions, TDS, saturation indexes, and isotope analyses have been reported and summarized in the new version in the subparagraph 2.2 (page 6, hydrochemistry…according to)

 

The attenuation capacity of the groundwater should be considered.

Reply: The role of aquitards on the attenuation capacity of the aquifer to potential contaminants have now been commented in the hydrogeological setting (page 6, subparagraph 2.2; the latter units…lower level)

 

5. Discussion

Please, improve comparison with literature findings.

Reply: comparison of data with literature findings has been improved in the new version to address the comment of the reviewer (page 19, subparagraph 5.2, as a consequence...to study site). Of note, all the three references provided by the reviewer have now been incorporated in the discussion and inserted in the reference list.