Review Reports

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

The title of the paper is some kind of modification for a better presentation of the research scope. I think some selected words should also be changed.

In the abstract section, it's expected to show your research novelty in the context of research output.

In the study area description, it may be important to give more data about water resources, including available surface water resources or even groundwater resources (i.e., number of wells, extraction amount …)

 Information about the sample needs to be more complete. How many samples with what spatial and temporal character did you capture, and how did you validate the test?

I think it's better to define IUA with the modelling approach.

I think it's better to show some table data in the new figure.

Compare the result of such a study in the context of a similar research paper

What's the novelty of the research? Focus on the research novelty in the introduction section with a more detailed approach

What's the limitation in the face of such a study?

The figure style needs some degree of modification

Author Response

We have revised the manuscript. See attached responses.

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

The manuscript addresses an important topic in the context of water resources protection, ecological sustainability, and catchment-level planning in South Africa. The study proposes a methodological framework for determining water resource classes and Resource Quality Objectives (RQOs), contributing potentially useful insights for practitioners and policymakers. However, the manuscript requires significant revisions to strengthen its scholarly contribution, clarity, internal consistency, and methodological rigor. Several structural, conceptual, and technical issues must be addressed before the paper can be considered for publication.

 

The introduction outlines the South African policy landscape effectively but does not articulate a clear knowledge gap in the global scientific literature. The paper presents a "novel stepwise methodology," but this is not clearly justified against existing frameworks (e.g., global RDM approaches, integrated catchment assessment methods, ecological reserve methods, scenario-based planning in water governance). The authors should explicitly state:
(a) What gap in current practice/knowledge this method fills,
(b) How the method builds on or diverges from previous approaches, and
(c) How findings generalize beyond this South African case.

The manuscript currently reads as a technical application report rather than a research contribution. Strengthening the framing will help position it within academic literature.

 

The manuscript lacks a conceptual framework guiding how the various steps (IUA delineation → water quality drivers → scenario analysis → classification → RQOs) connect conceptually. International water governance or ecological flow frameworks (e.g., ELOHA, IWRM, RDM theory) could be used to anchor the analysis. Without a theoretical foundation, the methodology appears descriptive rather than analytical.

 

Although five scenarios are listed (Table 3), the paper does not fully explain:

• How each scenario was constructed analytically.
• Which variables were adjusted (e.g., abstraction rates, WWTW performance, climate projections).
• Why each scenario was selected over other possible options.
• What inputs were used in the WRYM model.
• Whether uncertainty analysis was considered.
• How water quality scenario (Scenario 4) was quantified—currently it appears descriptive.

 

Some minor issues require correction:

• Table preceding Figure 3 appears in the PDF but has no caption, numbering, or mention in text. Must be labelled (e.g., Table 2), cited, and explained.
• Table 2 is referenced in the text but does not appear. Only the caption exists.
• Some keywords repeat words from the title

Author Response

 Find attached the revised manuscript.

Author Response File: Author Response.pdf

Reviewer 3 Report

Comments and Suggestions for Authors

Lawrence Humbulani Mulangaphuma, Nebo Jovanovic

 

The Determination Of Water Resource Classes And Resource Quality Objectives: A Case Study For The Mzimvubu To Tsitsikamma Water Management Area 7 (Wma7), South Africa

 

South Africa is considered a water-stressed country and has less water per capita than countries typically considered much drier, such as Namibia and Botswana. Furthermore, anthropogenic activities result in water pollution with phosphates (PO4), ammonia (NH4), nitrates + nitrites (NO3 + NO2), sulfates (SO4), and increased total dissolved solids (EC-TDS). This highlights the relevance and practical significance of the authors' study, which aimed to identify water resource classes and water quality targets using a large water management area (WMA7) as a case study to promote sustainable water use while maintaining ecological integrity.

The authors' research was based on extensive factual material obtained from the South African Department of Water and Sanitation and directly during fieldwork, and processed using ArcMap and Google Earth Pro GIS. A detailed research algorithm included the definition of integrated units of analysis—homogeneous watersheds (IUAs)—and high-priority resource units—catchment areas with their own specific ecological water needs (RUs) within WMA7. For each IUA, water quality and the factors influencing its changes were determined. An assessment of intra-annual changes in water resources up to 2050 was conducted taking into account environmental and climatic constraints. In the final stages, the results of all determinations were integrated into water resource classes, which, from a water use perspective, represent the varying levels of protection required for water resources and the extent to which water resources can be used. Recommendations were also formulated for water users on how to manage resources to promote sustainable water use while maintaining ecological integrity.

 

Overall, the study was conducted at a high professional level. The developed step-by-step quantitative and qualitative method for ensuring water resource protection can be applied to other watersheds.

 

A limitation of the study is the very limited set of water quality indicators, specifically the absence of trace elements such as arsenic, uranium, copper, cobalt, nickel, lead, and zinc.

 

Minor

 

Abstract

Abbreviations (RQOs, IUAs, WWTWs) must be explained when first used.

 

Table 2 should be removed from page 10 and placed after the heading "Table 2. Summary of hotspots, key water quality indicators and associated water users for the Mzimvubu-Tsitsikamma Water Management Area (WMA7)" on page 12.

 

Table 2

Why does the Table contain the "Resource Names" Kouga, Groot, Mthatha and Mbashe, but not the corresponding "Resource Units"?

 

Why does Kouga lack a Water quality impact rating?

 

Instead of “_RU09_I” and “_RU15_I” it should probably be “R_RU09_I” and “R_RU15_I”?

Comments for author File: Comments.pdf

Author Response

Find attached revised manuscript.

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

Comments and Suggestions for Authors

I would like to thank the authors for the revisions made and for providing detailed explanations in response to the previous review. The manuscript has improved; however, several points still require attention to enhance the quality of presentation.

The tables currently included contain a wide variety of information. Presenting these data in the form of figures or graphical illustrations is recommended to facilitate easier interpretation for international readers.

Additionally, Figure 4 requires further modification. Presenting the information contained in Figure 4 in the form of spatial maps with GIS-based capabilities would significantly improve readability and allow readers to better understand the spatial patterns and implications

Comments for author File: Comments.pdf

Author Response

See attachment.

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

The authors have addressed most comments, but three major elements need deeper revision:

(1) No real conceptual/theoretical framework is added

Needs a figure or explicit linkage using RDM/ELOHA/IWRM.

(2) Uncertainty analysis is still superficial

Should briefly explain sources of uncertainty and demonstrate how scenario ranges partially account for it.

(3) Scenario 4 (water quality) remains descriptive

A justification for qualitative assessment should be more explicit, and limitations should be acknowledged.

Author Response

See attachment.

Author Response File: Author Response.pdf