Performance of Conservation Techniques for Semiarid Environments: Field Observations with Caatinga, Mulch, and Cactus Forage Palma
Round 1
Reviewer 1 Report
The manuscript by Lopes et al. presents data from one-year of monitoring the rainfall-runoff and soil erosion processes in semi-arid conditions in Brazil. The plot-scale experimental setup is designed to compare four different soil conservation techniques, which are relevant for the region.
The topic fits into the frame of the journal WATER. The manuscript presents concrete and quantitative results which are of a high interest for a scientific community as well as for the local farmers. I appreciate the field work and the data analysis which quantitatively shows the effects of different soil cover on runoff and soil erosion. It is very challenging to collect runoff and soil loss data of a reasonable quality under natural conditions, therefore I understand that the detailed monitoring was done only during a single year. Fortunately, there were significant rainfall events during the period.
The manuscript is well written, has a logical structure, is easy to follow, the figures are well prepared. As a non-native English speaker, I hesitate to judge the language, but I would recommend additional proofreading as some parts need reformulating.
In summary, after the minor revisions, clarification of the raised questions/comments and the English proofreading I recommend the manuscript for publication in Water.
Remarks and comments:
- L. 38: instead of “waters bodies” should be “water bodies”
- L. 37-39 (also relevant for other general statements in the Introduction, e.g. ref. no 12): I realize that it is difficult to pick the relevant reference for a statement such as “soil erosion is a serious environmental problem causing this and that”, as there are hundreds of publications touching the topic. But, I would still recommend to reference a bench-mark paper or a large scale soil erosion assessment rather than a study from Jordan or Turkey. You may also consider to omit the references as the statement is generally well known. This is only my personal impression of the references following this kind of introductory expressions, keep it as it is if you do not agree.
- L. 57: rather “water retention” or “flood prevention measure” than “alternative flood protection”? Surely, such a conservation measure may have a certain impact on the runoff generation, they will help to postpone or reduce the peak discharge in the river network. But I would not call this as the flood protection measure.
- L. 59: should be “…processes DURING extreme rainfall…”?
- L. 61: instead of “assumes” should be “may have”? Maybe I do not understand the sentence.
- L. 62: should be constituteS. But, I suggest to slightly reformulate the sentence (or the whole paragraph), the text is of a lower quality than the rest of the manuscript.
- L. 64-65: This seems to belong somewhere else?
- L. 66-68: The objectives could be formulated better, more concretely, related to the final conclusions of the study.
- L. 75: The typical vegetation pattern of the region could be described in a bit more detail, as the Caatinga Biome character is not very well known outside Brazil.
- L. 82, table 1:
o Are the soil properties identical for three sites? To which location does the soil in the table belongs to? Describe briefly in the text, please.
o Include soil classification in the text
o use upper index where appropriate (units);
o soil texture classes are usually given in %, the g/kg is an uncommon way (even though easily translated into the per cents), also usually the classes are ordered by its size – CL, SI, SA;
o density is also given in uncommon units (usually g/cm3 or kg/m3);
o abundant dot after Depth (now Depth.);
o Ds is soil bulk density, Dp is particle density;
o what is H+A]?;
o what is P? (if porosity, I do not understand the units);
o what is CO?;
o Where is “soil infiltration capacity” advertised in the table caption?
- L. 85: There are 4 plots with different cover conditions at each of 3 sites (12 plots in total), correct?
- L. 114: how do these experimental plots (21 plots) differ from those mentioned on l. 85? Where there any replications (as 21 is more than 3 x 4)?
- L. 121, fig. 3: In what depth was the water content reflectometer (soil moisture probe) installed? How often was the probe recorded?
- L. 128: Consider modification (reformulation) of the caption
- L. 131: water IN the tanks?
- L. 131: the collection of the representative sample is tricky. How was the water containing the sediment homogenized? I doubt you were able to “shake” two 1 m3 tanks. Also, different soil fraction will settle in the first and the second tank.
- L. 133: By temporal characteristics is meant temporal rainfall intensity distribution?
- L. 138: I do not understand what is meant by the full randomization of the experimental design
- L. 143: rather plural? Rainfall events analyses
- L. 145: rather state the number of the erosive events, than the percentage (6.9 % out of 76 is 5.24)
- L. 148: are 7 events related to 6.9 %? It does not seem so.
- L. 149: Does this mean that it was a very exceptional rainfall event? Because the runoff and soil loss were larger from the events no. 1 & 4 which occurred in Feb and May. Why? Were the rainfall no. 1 & 4 also extreme?
- L. 151, fig 4: are the plotted soil moisture data from the neutron probes of from the water content reflectometer? Respectively, is it a continuous measurement (does not seem so) of biweekly measurement? If biweekly, I recommend to plot also the markers
- L. 164-160: belongs to the introduction section
- L. 174, table 2:
o To which period is the maximum rainfall intensity related? 5 min?
o Why not to give the soil water content as 0.xx, rather than using the x10-2 factor? It is confusing now.
- L. 192: I do not see the relevance of the Kostner and Suarez results for this particulate study.
- L. 198: Based on fig. 4, I do not see significant difference in the WC under different surface cover, maybe with the exception of the bare soil, which exhibits systematically lower WC at the Joao site. The exact statistical procedure of the Tukey test is not described, were only the mean values compared? WC difference of 1 % (Malaquias) is negligible.
o When you refer to soil moisture, do you describe the whole 0.5 m soil profile? Or a specific depth? What depth?
- L. 221, fig. 8: I do not understand to the antecedent WC as shown on the plots. Does it mean that the intensity above 25 mm/h happened always under initially dry conditions, but intensity bellow 20 mm/h always under moist conditions? I also do not understand the triangles.
- L. 229, fig. 9: Nice plot, I would say the key result of the study. I would appreciate to express the soil loss in e.g. kg/ha. The markers are too small, the key components of the box plot should be described (what is mean, median etc.)
- L. 245: …soil IS largely unprotected…
- L. 245 & 259: Is the prevailing sand component in the eroded sediment really a result of the raindrops impact (splash erosion)? Isn’t it because of the higher surface runoff, resulting in higher velocity and higher transportation capacity? Is your conclusion only a hypothesis or is it supported by data?
- L. 253: Do I understand correctly that all the plots were prepared in the beginning of the observation period and were not touched later? Therefore the bare soil (as well as the other plots) could change its properties due to the surface sealing, rill erosion, weeds intrusion, selective soil erosion etc. Can you please address this in the Methods, where you describe the plots?
- In the methodology, describe, please, how did you do the texture analysis (inputs for figs. 11 and 12).
- L. 275: Here you finally mention the importance of the runoff on the particle size of the eroded soil. This should come earlier (see my previous comment).
- According to the setup design the plot was continuously monitored with camera. Did any rills develop? Does the sediment come only from sheet erosion? If not, can the particle size be related to the erosion type (sheet or rill)?
Author Response
See the attached document.
Author Response File: 
Author Response.docx
Reviewer 2 Report
The authors investigated the smll-scale hydrologic process and the impact pf soil conservation techniques in reducing runoff and sediment losses under natural rainfall. The results of this study provided the guideline of conservation techniques for reducing the soil in the Caatinga, in Brazil.
The main weaknesses of the paper are:
1. Need more information on three sites (Maladuias, Edivaldo and João) , Why choose these three sites? Are the plots setting of each site the same?
2. there are many confusion and errors in Table1. For example, the soil texture unit should be consistent with the results, “g kg-1”to “%”. The units of P(phosphorus) should be “g kg-1”. In addition，What is the significance of measuring the soil physical and chemical characteristics of different soil layers? Are these data averages of three sites? How the sampling was done (auger, core, shovel)? Were all soil samples collected in the same day?
3. I am confused about the number of experimental plots. “Soil and water monitoring was performed in twelve experimental plots with different cover conditions” (Line 84), “From October 2016 to October 2017, runoff and sediment yield were monitored and characterized in the 21 experimental plots.”(Lines 110-111).
4. Line 145, “70 mm h-1”to “70 mm h-1”. Table 2, “mm h-1”to “mm h-1” and “×10-2”to “×10-2”.
5. The figures of runoff and sediment loss in Figure 2 needs to be recombined. I think it's better to put four cover conditions together in every event.
6. The characteristics of natural rainfall are missing in “3.1 Event analysis”.
7. What do the triangles and circles represent in Figure 8.
8. The cause interpretation and mechanism analysis of different cover conditions are missing.
Author Response
See the attached document.
Author Response File: Author Response.docx
Round 2
Reviewer 1 Report
Dear Authors,
I appreciate the clarification and improvement of the manuscript.
I suggest that the authors go for additonal check for small corrections in the language (even though as a non native English speaker I hesitate to point out the exact flaws).
Please, see my additional minor comments below.
l. 78-81: Consider reformulation of the sentence, please. Maybe split into two sentences?
l. 99: Correct the sentence, e.g. such as: “Hence, the presented data in Table 1 CORRESPOND to the mean values.”
l. 100: I am not familiar with “Ultisol Eutrophic Typical”. Please double-check, whether the “typical Eutrophic Ultisol” shouldn’t be used.
l. 103: Please double check the OC values. The OC concentration seems to be low (by one order), aren’t the correct units per cents?
l. 256, fig. 8: Kilograms are abbreviated as “kg” (not Kg). Even better would be to recalculate the values to kg/km2 or kg/ha (as in Fig. 9).
l. 314: “… erosion on the plots” (abundant FOR)
Author Response
.
Author Response File: 
Author Response.pdf
Reviewer 2 Report
The manuscript entitled “Performance of Conservation Techniques for Semiarid Environments: Field Observations with Caatinga, Mulch and Cactus Forage Palma” has made great revisions and improvements. All the revisions s are reasonable.
Author Response
.
Author Response File: Author Response.pdf
