The Impact of Expanding Eucalyptus Plantations on the Hydrology of a Humid Highland Watershed in Ethiopia

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

All comments in PDF file. 

Designate every comment with number, provide answer to every comment paragraph and provide row number for every change made in corrected manuscript.

Comments for author File: Comments.pdf

Author Response

Dear Reviewer

Thank you for your review. Our response to the comments and the manuscript with marked changes is attached

Thanks again

For all authors

Tammo Steenhuis

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

Dear Editors,

The manuscript titled "Dynamics and impact of eucalyptus plantations on water availability under a monsoon climate in a watershed in the Ethiopian Highlands" by Fenta et al. presents an interesting and potentially impactful study on the hydrological effects of eucalyptus plantations in a region with downstream implications. However, I have significant concerns regarding the novelty and depth of the analysis that need to be addressed before the manuscript can be considered for acceptance.

My specific comments are as follows:

• The statement claiming a "lack of comprehensive understanding of how eucalyptus water use changes the hydrology in the Ethiopian Highlands" appears biased. The scale of the study (39 km²) seems insufficient to make such a broad generalization. Furthermore, the authors need to differentiate their work from existing studies, such as the ones cited below, and explicitly state the novel contributions of their research:
  https://doi.org/10.3390/w11112299
  https://doi.org/10.2478/johh-2013-0004
• The sentences in lines 54-57 require clearer and more robust supporting evidence or justification.
• To make Figure 1 more effective for an international audience, particularly researchers outside of Ethiopia, please add a clear inset map showing the location of Ethiopia and its relationship to downstream countries like Egypt and Sudan.
• The methodology described for detecting different land cover types (plantation, cultivated land, shrubs, eucalyptus, grassland) lacks sufficient detail. Authors should provide a more comprehensive explanation of the classification process, ideally including field photographs and/or high-resolution imagery from sources like Google Earth to support the accuracy of the classification.
• The discussion section is currently weak. Authors need to significantly expand this section by comparing their findings with similar studies conducted in regions with comparable monsoon climates. Furthermore, the discussion should emphasize the significance of their results and provide concrete insights into how policymakers can utilize these findings for informed decision-making.
• The references in the introduction section should be updated to include relevant and recent publications from 2024-2025

Regards

Author Response

Dear Reviewer

Thank you for your review. Our response to the comments and the manuscript with marked changes is attached

Thanks again

For all authors

Tammo Steenhuis

Author Response File: Author Response.pdf

Reviewer 3 Report

Comments and Suggestions for Authors

Comments hydrology-3578428

This manuscript addresses the hydrological consequences of eucalyptus plantation expansion in the Ethiopian Highlands, focusing on the Amen watershed. The topic is both relevant and important, particularly in the context of upstream–downstream water security in the Nile Basin. The combination of remote sensing, land cover analysis, and hydrological assessment is appropriate, and the manuscript presents an interesting dataset.

However, the current version would benefit from a number of clarifications and revisions. In particular, the causal links between eucalyptus expansion and hydrological response require further substantiation, and the treatment of methods, data harmonization, and visualization needs refinement in order to ensure transparency and reproducibility.

 Title and Abstract Section

The title is clear but slightly long and lacks ‘mechanistic’ expression. Suggest revision to

"Hydrological Impacts of Eucalyptus Plantation Expansion under a Monsoon Climate in the Ethiopian Highlands".

Abstracts are heavily laden with data and lack clear structural delineation (objectives-methods-results-conclusions).

The expression ‘increased yearly discharge’ is easily misinterpreted and contradicts the decrease in baseflow. It should be made clear that the increase in precipitation exceeds the increase in AET, resulting in an increase in the total annual runoff trend, while the dry season flow and baseflow are still decreasing.

Introduction

After line 86, add a paragraph that explicitly states three research objectives: Specifically, we aim to (1) quantify the extent of eucalyptus expansion; (2) assess changes in evapotranspiration and streamflow; and (3) assess how land cover change affects the timing of runoff and baseflow reduction.

 

Materials and Methods

lines 121-126 (rainfall data). Supplementary information on how the ‘Amelia package’ is parameterised and error-controlled to interpolate missing data, or to give the average percentage and spatial distribution of missing data.

The time-dependent term ho in line 138-139 (Equation 2) is not clear. It is suggested to specify whether the time unit (years since 2002) is 1 unit per year and whether it is regressed on measured flow data.

In lines 154-158 (Effective rainfall), it needs to be clarified whether ‘effective rainfall’ is based on PET or AET; in the case of PET, it is recommended that it be stated which data source was used (not stated in the text).

The time spans of different datasets are inconsistent (e.g., rainfall: 1990–2024; streamflow: 2002–2009, 2015–2018; AET: 2009–2024). Please explain how these discrepancies were addressed and whether temporal alignment or data imputation was applied.

  

Results

lines 227-246 (land use change), with abbreviated presentation of classification accuracy. Suggestion to add full confusion matrix, or transfer Table S1 from supplementary material to the text, or present Kappa, user/producer accuracies, etc. in a table. 

 Figure 3 (page 8) Missing Scale and Coordinate System Information.

In line 283-310, figure 6 is based on a runoff threshold of 20 mm cumulative runoff, which is an oversimplified definition. It is recommended that it be clarified whether this threshold is based on above average baseflow, and that it be supported by reference to commonly used metrics such as the initial runoff index or ‘time-to-peak’.

The treatment of data consistency is slightly ambiguous in lines 331-344.

The attribution of baseflow reduction and delayed runoff solely to eucalyptus expansion may overlook confounding factors such as rainfall spatial variability and lateral subsurface flow. Consider using comparative sub-watersheds or hydrological modeling (e.g., SWAT, HBV) to strengthen causal links.

 

Separate and quantify the relative contributions of “climate change” and “land use change” to hydrological changes. Their current combined discussion may obscure key findings.

  

Discussion

The discussion section of the manuscript is too brief, with only 2 citations, and this cannot be tolerated. T There is noticeable redundancy between the Results and Discussion sections, particularly in the description of evapotranspiration and baseflow dynamics. Consider condensing or integrating overlapping content. The authors are encouraged to place their findings in the context of prior studies. For instance, how do the observed reductions in flow compare with afforestation impacts reported in Farley et al. (2005)? Are the AET values for eucalyptus consistent with previous field or modeling studies in Ethiopia? In line 407-419, it is recommended that comparisons of cases and results with similar studies of Eucalyptus in other regions (e.g., South Africa, Brazil) be added to strengthen the breadth of the discussion. The assumption in Figure 11 that 67% of the watershed contributes to outlet flow should be justified with supporting data or references. For example, slope gradients, soil infiltration capacity, or known fault structures may be used to infer non-contributing areas.

Others

It is recommended that the inter-annual water balance tables (P, AET, Q) be added to the text or appendices to enhance trend comparisons.

The manuscript would benefit from a careful editorial review to address formatting inconsistencies, such as incorrect line breaks, uneven spacing, and inconsistent units in text and figures. Please ensure formatting is cleaned up before resubmission.

Author Response

Dear Reviewer

Thank you for your review. Our response to the comments and the manuscript with marked changes is attached

Thanks again

For all authors

Tammo Steenhuis

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

Comments and Suggestions for Authors

Accept in present form

Reviewer 2 Report

Comments and Suggestions for Authors

The authors have adequately addressed all of my previous comments. I believe the manuscript is now suitable for acceptance, after minor English language revision to correct some errors.

Comments on the Quality of English Language

The authors have adequately addressed all of my previous comments. I believe the manuscript is now suitable for acceptance, after minor English language revision to correct some errors.

Reviewer 3 Report

Comments and Suggestions for Authors

The manuscript has been significantly improved following the major revision. The research topic aligns well with current international concerns regarding water resource management and land use change. The content is substantial, the methodology is clearly articulated, and the data support is adequate, offering both empirical depth and practical policy relevance. I recommend the manuscript be accepted for publication. 
The following minor comments are provided to help further improve the final version:
In Section 2.3.2, it is mentioned that streamflow data were obtained from both the Abbay Basin Development Office and MoWIE. It would be helpful to clarify whether consistency checks were conducted between these two datasets (e.g., whether the same rating curves were used).
A few references are cited in-text by author and year (e.g., Davidson (1989) in [14]) but are not included in the main reference list. Please ensure that all cited works are properly listed and the reference section is complete.