Rainfall–Groundwater Correlations Using Statistical and Spectral Analyses: A Case Study on the Coastal Plain of Al-Hsain Basin, Syria

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

This study has a solid data foundation, a systematic analytical framework, and diverse methodological approaches. It provides valuable insights into groundwater recharge mechanisms in semi-arid regions of Syria. However, the manuscript requires substantial revisions, as several issues remain regarding focus, methodological clarity, statistical interpretation, and depth of discussion.

1. The background section is informative, covering global, regional, and Syrian water-resource issues, along with a broad review of statistical and spectral methods. However, its structure is somewhat scattered, and some paragraphs are not closely aligned with the study’s main theme. The research gap and the necessity of the study are not sufficiently emphasized.

2. The research objectives are mentioned in multiple sections but are not presented in a focused, clear, and verifiable manner.

3. The manuscript does not describe missing-data handling, data-quality control procedures, or how seasonality was treated.

4. The criteria for grouping wells lack explicit classification standards or quantitative justification.

5. The extremely high consistency between Pearson correlations and regression results (e.g., correlations near –1) needs explanation, particularly regarding whether such patterns result from seasonal synchrony or structural characteristics of the aquifer.

6. Technical details of the wavelet analysis require clearer specification (e.g., mother wavelet, scale ranges, COI definition).

7. The very high negative correlations across most wells (–0.95 to –0.99) require deeper interpretation and hydrological justification.

8. The spectral-analysis results are insufficiently presented and interpreted; key frequency bands and significant coherence regions should be explicitly highlighted.

9. The manuscript lacks a systematic discussion of research limitations, such as the short monitoring period, potential pumping influences, and the possibility that monthly data conceal event-scale recharge processes.

10. The applicability and constraints of the proposed “transferable analytical framework” are not clearly defined.

Author Response

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Author Response File: Author Response.docx

Reviewer 2 Report

Comments and Suggestions for Authors

1. My main concern is the novelty of the manuscript. The authors themselves have cited numerous studies that have used the combination of statistical and spectral tools in various regions, but how their work is distinguished from others is still not discussed explicitly. The authors should mention the novelty especially in terms of data resolution (may be), basin settings, methodological combo or perhaps predictive accuracy.
2. In the abstract, the authors have used many technical jargons that might overwhelm the general readers and also it jumps too quickly to the results and methods. I suggest restructuring the section to highlight the regional problem, context and then key methods, and findings.
3. Fig.2 and Fig. 3 can be shifted to supplementary section and they feel not important in the main text.
4. Remove Fig. 11 and present this info in a simple way (may be a table)
5. Fig. 16 caption is misplaced. Moreover, the font is too small to comprehend as the figure is already overloaded with the information.
6. Pearson r-values are presented as the main evidence for rainfall–groundwater coupling, yet this metric assumes linearity. Groundwater responses are often nonlinear, especially in fractured or karst systems. A suggestion would be to discuss this limitation explicitly and perhaps consider adding non-linear analysis if possible.
7. Fig. 20: The wavelet coherence plots are visually appealing but underexplained. Readers unfamiliar with time-frequency methods may struggle to interpret the phase arrows and coherence zones.  Include a concise tutorial-style figure or schematic explaining what “in-phase”, “anti-phase”, and “lag” relationships mean in your hydrogeological context.
8. Some sections, especially section 3 goes into excessive details that barely help advancing the main argument. Similarly, section 5 contains too much information and at some point, the figures and images bloat the manuscript and make key insights harder to spot. Therefore, it is highly recommended to restructure the sections to prioritize clarity over comprehensiveness. Combine similar figures (or shift in supplementar), trim background history and focus results on answering 2-3 core research questions.

Author Response

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Author Response File: Author Response.docx

Reviewer 3 Report

Comments and Suggestions for Authors

Within the manuscript authors focus to interconnection between precipitation and GW level along the site area. To enable relavnt conclusions, authos offere plenty of methods, at some point not reasonable thus leading to the repetition. Figures are not of apropriate quality locally, writing demands significant improvements. Number of figures corresponds to 23 while the manusprit cosissts o fin total 37 pages which leads away from keepeng the focus,

Introduction is very brief and does not offer relevant background.

2.2. Vegetative cover, topography, and lithology shold be changed to 2.3.

2.5.1 Iranian case studies and recharge mechanisms should be changed to 2.4.1.

2.5.2 Climatic stress and groundwater responses in Syria should be changed to 2.4.2.

Under the ch. 2. review of the literature, sub chapter 2.5. does not fit. Initially, no references have been citeed. Furthermore, the contetent referrs more to site description rather than Review of the literature.

I warmly suggest to use  the term Literature review insted of Review of the literature.

What is cosidered under the term groundwater depth? Usually used term is GW piezometric head , or GW elevation or GW level. Depth can be considered opposite when looking at Figures 6.-10. where depth increases with precipitation increase whuch is duable. I hereby attach the text from the manuscript „The results demonstrated strong negative correlations across all wells, indicating that higher rainfall is generally associated with shallower groundwater levels.“ This is in collision with notation on Fig. 6-10.. The terminology is not the same along the manuscript.  Hereby authors us e GW level. Please, specify the meanng of the GW depth or adjust the therminology.

Figure 20 is not of appropriate quality and cannot be read out for purpoe of Peer review. This has to be enlarged or the quality is to be improved up to appropriate level.

Why cross correlation is used to obtain time lag between relevant variables if coherence i salso used within the manuscript? There is a huge number of publications highlighting the superiority of the coherence over the cross correlation to obtain for time lag, some of them I attach below, which can be potentially helpfull:

Characterization of seawater intrusion dynamics under the influence of hydro-meteorological conditions, tidal oscillations and melioration system operative regimes to groundwater in Neretva valley coastal aquifer system; I Lovrinović, V Srzić, I Aljinović; Journal of Hydrology: Regional Studies 46, 101363

Briciu, A.E., 2019. Changes in physical properties of Inland streamwaters induced by earth and atmospheric tides. Water 11. https://doi.org/10.3390/w11122533

The amnuscript aims for systematization and improvements. First of all it has to be shortened, some figures are not mandatory. Once tha manuscript is shortened, the terminology used has to be improved as well as figures quality.

Methodology section is missed with all steps included so the reader can perform methodological repetition to better understand the contribution.

Conclusion section represents a way of repetiotion of previously written manuscript content. Authors should highlight a novel, unique, site releted facts arose from the study. Deep understanding of GW response to precipitatipon has not been elaborated within thje mansucript as stated by authors.

Comments on the Quality of English Language

Several commnets given to aurhors. mostly in a way of term construction.

Author Response

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Author Response File: Author Response.docx

Round 2

Reviewer 1 Report

Comments and Suggestions for Authors

The revised manuscript has been significantly improved, especially the research methodology, which has been rigorously described.