Climate Change Effect on Water Use Efficiency under Selected Soil and Water Conservation Practices in the Ruzizi Catchment, Eastern D.R. Congo

Round 1

Reviewer 1 Report

The paper studied possible climate change impacts on crop production (maize) in Congo, considering two RCP scenarios, crop simulation production, and two different systems (conventional and tied ridge). Besides, water-efficient use was also evaluated considering climate change. The models AgMIP Regional model (RIA) was calibrated and its sensitivity, and the vulnerability of the maize crop to climate change.

The paper is well-written, with a robust Introduction section and good structure. My greatest concerns are related to some aspects of the methodology. Such aspects are:

Line 105: AW4 what means this "4"?

Lines 138-139: The authors used AgMERRA from NASA to fill gaps in the climate series, but how efficient is this process in filling daily climate data, especially rainfall data? Please, clarify this aspect. 

- lines 159-160: 29 nine GCMs and five were chosen. But, how was it made? Criteria? Table 1 is very confused. I could not understand this part of the methodology and more details are necessary. 

- lines 213: what means "1.0". And the same for Table 2. Such values are in relation to some previous information. What are the units? 

- Crop data were collected between 2011-2019, but the current climate is up to 2009. How to overcome this gap between the data? 

The conclusion section can also be improved. It is very "rush". Maybe begin with a summary paragraph and then described them in topics.

Author Response

Please see in the attachment the response to your comments. 

Author Response File: Author Response.docx

Reviewer 2 Report

This study explored the effects of different agricultural management strategies on the soil water balance, crop water use efficiency and yield in eastern Democratic Republic of Congo (DRC) under the future climate scenarios using crop modelling. Understanding the response of agricultural production to the climate change conditions and developing strategies to couple with the dramatic influence of climate uncertainty on food production is one of the critical challenges that we are facing. The topic is interesting and the paper is well written. I suggest a minor revision before accepting for publication by land.

There are several detailed comments that authors should consider

Table 1

The standard used for the classification of the climate regime is required. Please add more information on this in the method section.

Line 200

2.3 section is missing. Please check.

Line 258-261

this is repeat information. Please remove it.

Line 414

The figure caption does not match with the graph. Please check.

Discussion

How did you consider the effect of soil types on the water balance when conducting the crop modelling? Across the big study region, the soils are supposed to be heterogenous. Did you consider a classification of the soil types in the study region and develop the models based on the soil types? The crop modelling is a plot-level simulation. It might be difficult to consider the spatial effects on the interested soil water and crop yield through just crop modelling. This might be an interesting direction that you could consider in your future study. The following papers might be useful for you on understanding how to consider the spatial effects.

Zhao, D., Wang, J., Zhao, X., & Triantafilis, J. (2022). Clay content mapping and uncertainty estimation using weighted model averaging. Catena, 209, 105791.

Zare, E., Wang, J., Zhao, D., Arshad, M., & Triantafilis, J. (2021). Scope to map available water content using proximal sensed electromagnetic induction and gamma-ray spectrometry data. Agricultural Water Management, 247, 106705.

Author Response

Please see in the attachment the response to the comments

Author Response File: Author Response.docx

Reviewer 3 Report

Manuscript entitled “Climate change effect on water use efficiency under selected soil and water conservation practices in the Ruzizi catchment, Eastern D.R. Congo” by the Espoir M. Bagula and team.

Authors highlighted the concerns of effectiveness and sustainability of Soil and Water Conservation (SWC) management practices as adaptation options to climate change and high intra- and inter-annual rainfall variabilities in eastern Democratic Republic of Congo.

They have reported based on the study conducted in the Ruzizi plain, a dryland area, to assess the performance of maize under two RCP (4.5 and 8.5) and two SWC practices (TR & CT).

They found that use of efficient SWC practices could therefore be a promising strategy in reducing potential losses from climate change in drylands of eastern DRC.

Abstract: Written well,

Keywords: Ok

Introduction: well define, need updated literature (20 to 22) mainly in relation to RCP 4.5 & 8.5

L 83-99 need restructure with define research gaps and objectives in quantify manner (hypothesis)

Materials and Methods: overall ok, following correction needed

Study site and data collection: add geographical references and map of the study are with geotagged.

Methodological approach: well define

Collection and correction of historical climate data: very informative

Future climate projection ……………GCM: excellent

Results: need more quantify manner, like how much percentage variation in both scenario

Figure quality is excellent,

Discussion: need major modification, pl add relevant information of Maize and global scenario with references to maize and other crops. This section lacking the latest studies, needs to be update with latest information.

Conclusions: this very generalize, need major modification as per our results and add quantifying data.

Overall, manuscript is very informative discussion and conclusion sections need major modifications as suggested. 

Author Response

Please see in the attachment the response to the comments. 

Author Response File: Author Response.docx

Round 2

Reviewer 1 Report

Dear authors:

from my side, I believe the manuscript is good enough for publication.

Reviewer 2 Report

N/A

Reviewer 3 Report

They have incorporated all suggestion and comments in revised MS, now it would be accepted