The Effect of Landscape Interventions on Groundwater Flow and Surface Runoff in a Watershed in the Upper Reaches of the Blue Nile

Round 1

Reviewer 1 Report

The following comments are given for the authors to improve and to enhance the quality of the MS.

Line 22: What type of “discharge” data? Every “ground water” is suggested to change to “groundwater”. Line 51: “increase” is repeated. ine 54: “both: is supposed to be put before “land”.

    5.Line 76: “of” omitted?

Line 82: “decrease” should be “decreases”. Line 85: “only for current conditions” is repeated. Line 94: There is a grammatical error in “The watershed is in the headwaters of the Blue Nile basin and characteristic for many similar watersheds that have significant base and interflow during the dry phase.” The meaning is not clear. Line 135: “during base flow” is weird. Line 137: “multiplying that times two thirds…” is weird.

11 Line 156: “use” should be “used”.

12 Line 158:”will use” should be “also used”?

13 Lines 169-171: How to determine these values of parameters?

Line 171: How to define and determine the half-life of the aquifer? How to determine or measure the value of Perc in Eq. (1)? Line 198: “medium” should be “median”. Line 199: “23% of time” cannot read from Figure 2. Lines 215-216: “the groundwater flow consists only of baseflow“ should be “the baseflow consists only of groundwater flow”. Line 248:The word “compromised” is weird. Sections 3.1 and 3.2 are suggested to move to Section 2.2. In Table 3,

(1) How are all the values obtained? Many values seem not feasible.

(2) Why is the sum of the proportional area A1, A2, and A3 not equal to 1?

(3) The vales of the same parameters for different years are the same, why?

(4) How to determine the values of the parameters according their definitions, equations or methods given in the text? Please explain in detail.

Line 259: What is the content or component of “cumulative discharge”? Line 264: What is “precited”? The scale of Fig. 5 diminishes the apparent error. Line 272: How can it be “a linear reservoir”? I cannot understand and don’t believe “the outflow could be best explained by a linear reservoir (Table 3)”. Give an explanation. Lines 277 to 279: How can anyone control the same conditions “At the same time for equal rainfall amounts” before and after implementation? They are actually different times for different rainfall amounts before and after implementation. Line 295: “capacity” should be “rate”. Line 331: “the number of” should be “a number of”. There is a lack of new findings or new contributions emphasized in the Conclusion section.

Author Response

Dear Reviewer

Thank you for your comments

Please see attached pdf for the responses to the comments together with the marked up manuscript

Regards

Tammo and Adugnaw

Author Response File: Author Response.pdf

Reviewer 2 Report

In this manuscript, the parameter efficient distributed (PED) model was implemented to a watershed in the upper reaches of the Blue Nile. In general, the given work is an application of PED and the groundwater flow index (GWFI) which is in short of novelty. I do not see much scientific contribution to general water science. Besides, for an application-based manuscript, the given draft is way simplified in methodology section (that’s probably because authors were using established methods and approaches). Therefore, I have to suggest reject from publication.

Author Response

Dear Reviewer

Thank you for your comments

Please see the attached pdf for the responses to your comments together with the marked up manuscript showing the changes made in red font

Regards

Tammo and Adugnaw

Author Response File: Author Response.pdf

Reviewer 3 Report

General comments

This is an interesting study on the impact of land-use change from forests to croplands on watershed hydrological cycle in the Ethiopian upper Blue Nile region. The study is interesting and well structured, and has important implications for sustainable land-use, environmental management, and overall agro-ecosystem functioning. Yet, the level of writing is somewhat basic, and several times seems like having errors. I would therefore ask the authors to thoroughly revise the manuscript, and if needed, consult with a professional hydrologist / agronomist. Regardless, the authors seem to confuse between land-use on the one hand, and management practices on the other hand. Land-uses include croplands, forest lands, rangelands, etc. each land use can be managed in several practices. For example, croplands can go under intensive tillage, conservation tillage, no-till, etc. I would ask the authors to go throughout the manuscript and make the required adjustments. Further, please send the manuscript for professional English review before resubmission. 

 

Abstract

While going through the abstract, it is not clear what are the land management practices. Meaning, are they forest vs. cropland?

Regardless, in lines 27-28, you stated that 'more water infiltrated in the treated degraded hill slope area' – what do you mean by saying 'treated'? Please elaborate.

 

Introduction

Line 40. Please modify to 'agricultural production' instead of 'biomass production'.

 

Line 51. Please delete one of the 'increase'.

 

Lines 53-54. The sentence 'In Iowa in the Mississippi river basin land management practices and base flow increased both since the 1940’s' is unclear. What do you mean by saying 'land management practices'? Is it land restoration practices?

 

Line 56. 'land management like afforestation' – here is to answer to my previous comment. Afforestation is not a land management, but a land-use. You can apply different afforestation methods or practices. Please correct this sentence, and make the needed adjustments throughout the manuscript.

 

Lines 60-63. 'In the Ethiopian highlands, the effect of land management practices on roundwater flow has , in the semi-arid highlands with generally greater evaporation than precipitation during the rain monsoon phase, bunds and associated infiltration furrows in the uplands, generally, decreased direct runoff and increased biomass production by increased water availability in the valley bottoms' – the sentence is vague and unclear. Please rewrite.

 

Line 65. 'structural land management practices' – what do you mean by 'structural'?

 

Lines 66-67. 'contour infiltration furrows' – please modify to 'contour furrows'.

 

Line 69. 'structural soil and water conservations' – again, what do you mean by 'structural'?

 

Lines 85-86. Please delete one of the 'only for current conditions'.

 

Materials and methods

In the 'Description of study area', instead of mean (annual) daily temperature, please provide the mean daily temperature in the coldest and warmest months. Also, please provide information on the characteristic annual distribution of precipitation.

 

Line 131. Please provide a citation for the single ring infiltrometer method.

 

Line 164. What are 'degraded areas'? Please elaborate.

 

Discussion

Even in the discussion it is still not clear what are the causes for land degradation across the study site, and what is the nature (characteristics) of the degraded areas. Also, it is not clear what are the specific measures for land restoration (or land management practices as named by the authors). These aspects should be clarified in the beginning (introduction section) already of the manuscript, and their implications should be discussed in the discussion section.  

Author Response

Dear Reviewer

Thank you for your time and comments

Please see the attached pdf for our responses to your comments together with the marked up manuscript showing the changes made in red font

Regards

Tammo and Adugnaw

Author Response File: Author Response.pdf

Reviewer 4 Report

Implementing land management approaches to reduce runoff and promote infiltration to groundwater has also been recognised as a major factor in catchment water management. The methods and approach are scientifically sound. This paper describes a classic research project investigating the impact of land management (gully rehabilitation, land enclosures, infiltration furrows with bunds, stone bunds, waterways, planting of trees and fodder plantation and treatment of degraded lands) on increasing groundwater baseflow.

The PED model has been previously used in the area so it makes sense to utilise this approach. Results show that slowing down runoff in the catchment (using land management approaches) promotes infiltration and increases in groundwater baseflow (less surface runoff). These are great outcomes for the catchment works undertaken and demonstrate an improvement in both land and water management.

My only issue with the paper is that moderate English changes are required. For example, line 248 should be "comprised" and in Figure 5 it should read "predicted". Please check the rest of the paper thoroughly.

Overall, I find this paper worthy of publication as it provides a robust and repeatable approach to land and water management in the upper reaches of the Blue Nile.

Author Response

Dear Reviewer

Thank you for your nice comment

Please see the attached pdf for our responses together with the marked up manuscript showing the changes made in red font

Regards

Tammo and Adugnaw

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

All comments are well revised and/or replied. No further comments.

Author Response

Thank you so much for help in improving the  manuscript

Best regards

Tammo and Adugnaw

Reviewer 2 Report

I can see authors were trying to revise the manuscript in better ways in the revision. In addition, I agree that we only find few groundwater related research work in that area. However, the primary reason is because of the lack in data. Quite a few assumptions are needed to conduct any groundwater related work. How do you justify that? You should point that in the Discussion in case other researchers may wonder the same issue. 

Author Response

Dear Reviewer

Thank you for your time and positive comment. We have revised the discussion in the revised manuscript in accordance your comment. The text in blue in the attached response and revised manuscript is new material added  to the manuscript. For ease of reading we did not show the deleted text.

Regards

Tammo Steenhuis

Author Response File: Author Response.pdf

Reviewer 3 Report

I congratulate the authors for the serious work invested in revising this manuscript.

Author Response

Thank you for your help in improving the manuscript

Regards

Tammo

Reviewer 4 Report

I did not have any major issues with paper on my previous review; and since then, the paper has been further improved by the authors taking on comments from other reviewers.

Author Response

Thanks for the positive evaluation

Tammo

This manuscript is a resubmission of an earlier submission. The following is a list of the peer review reports and author responses from that submission.

Round 1

Reviewer 1 Report

The authors present an numerical analysis on effect of land management practices on hydrologic processes in a mountain basin. The content is interesting and fits the scope of this Journal. For a better content, I would suggest major revision upon consideration of some comments and/or suggestions listed as below. 

1) From Line 76 to 78, it seems the sentence, "The objective of this study is to add to ... Humid Ethiopian highlands.", is incomplete. Please revise it. 

2) In Figure 1, please increase the figures resolution and mark the longitude & latitude on the figure. 

3) The temperature data was recorded 18 km far from the target basin. The authors are suggested to address or verify that the temperature data is acceptable for the hydrological analysis. 

4) In Eq. (1), please explain the variable of Perc & St. A2 should also be revised to have a correct subscript. The authors are suggested to revise thoroughly for typos of this kind. 

5) In Line 171, It seems the sentence, "The medium steady state .... is exceeded by the rainfall intensity 23% of the time.", is unclear and not readable. Please re-write this. 

6) Figure 2 is not clear. Please redraw to increase the resolution. 

7) From Lines 209 to 2011, please provide evidence for the discussion, "Consequently, the rain falling on approximate 60% of ... such as faults that are highly permeable."

8) From Lines 231 to 239 and Figure 5, the content as well as the figure cannot match. Please carefully revise to make sure the definition of each line and relating content are all correct. 

9) In Line 252, please re-write the correct form of "pre and post implementation."

10) In Table 4, please use brackets for unit for a clear table content. 

11) In Line 260, again, the sentence, "The rainfall intensity exceeded .... by 23% of the time.", seems unclear. Please re-write it. 

12) In Line 281, please revise the sentence starting by "The is water in the root zone was subject..."

13) In Line 296, it seems the manuscript is lacking of information of the number of land management practices installed. Please add some more information to support this conclusion. 

14) Based on the manuscript, the authors are invited to consider some other international literature about grid-based hydrological modeling in a large watershed:

     A) Chiu, Y.J., Lee, H.Y., Wang, T.L., Yu, J., Lin, Y.T., and Yaun, Y. (2019) Modeling sediment yields and stream stability due to sediment-related disaster in Shihmen reservoir watershed in Taiwan, Water 11, 332. 

    B) Chen, Y.C., Wu, Y.H., Shen, C.W., and Chiu, Y.J. (2018). Dynamic modeling of sediment budget in Shihmen reservoir watershed in Taiwan. Water 10, 1808. 

    C) Liu, K.F., Wu, Y.H., Chen, Y.C., Chiu, Y.J., and Shih, S.S. (2013). Large-scale simulation of water mass transport: a case study of Tsengwen  reservoir watershed, southwest Taiwan. Natural Hazards 67, 855-867. 

15) Some minor typos are required to revise thoroughly. 

Reviewer 2 Report

The manuscript focuses on the rainfall-runoff relationship in a small watershed in Ethiopia, in which some soil and water conservation practices were implemented. A relatively simple hydrological model PED is calibrated on the basis of recorded weather and stream flow data. The effect of conservation practices are captured by the model with reasonable accuracy. The manuscript can be considered for publication in Water, but it must be considerably improved.

Here are my main comments to the authors:

1. Please provide a more detailed description of the PED model and the values of all calibrated parameters (Smax are not reported) 

2. Please provide data on all components of the hydrological balance, What was the amount of evapotranspiration and deep percolation ? How was the groundwater split between interflow and groundwater flow in the wet season ?

3. Please provide basic information on groundwater in the region (depth to groundwater table, type of aquifer rock)

4. How does the increase in GWFI after conservation practices compare to other studies and to the expectations ?

L209-213 - Is this estimation of deep percolation consistent with land use and geological conditions? 60% of rainfall seems very large. For the runoff amounting to about 25-30% of rainfall, this would mean evapotraspiration of about 10-15% of rainfall, i.e. quite low.

 

Minor points:

L40 possible error "originalists"

L49 correct "runoff.in"

L58 remove the full stop after "In contrast"

Fig. 6. Caption and legend, correct the typo "implemntation".

L73-74 - The meaning of the sentence is not clear, models can be validated on existing data, not on predictions of the future.

Section 2.3.1 - Actually you do not discuss the separation between interflow and baseflow in your model, so the title is misleading.

Eq(1) - What is Perc ? Percolation ??

Reviewer 3 Report

Please, see the enclosed file.

Comments for author File: Comments.pdf