Raindrop Energy Impact on the Distribution Characteristics of Splash Aggregates of Cultivated Dark Loessial Cores
Round 1
Reviewer 1 Report
Review
The manuscript titled " Raindrop Energy Impact on The Distribution Characteristics of Splash Aggregates” by Fu et al., assessed the effect of raindrop energy on the splash distance and particle size distribution of aggregate splash erosion, (ii) establish a prediction equation for splash erosion in this area, and (iii) predict whether a certain raindrop energy will break up the aggregates to the greatest extent by comparing the characteristic parameters of the aggregate fractions. The work is interesting. Please check all the detailed comments and questions provided below. Some are particular relevant to consider my recommendation for acceptance.
Detailed Comments
1. Abstract
The “Abstract” is well written. The structure is fine.
2. Introduction
I suggest to extend it with recent works available in literature dealing with the article
3. Materials and Methods
The photo or scheme of the experiment is missing
4. Conclusion
In this form, the conclusion should be in points
5. Language problems
The English language requires revision. There are quite many typos.
Comments for author File: 
Comments.pdf
Author Response
Response to Reviewer 1:
Thanks for the comments on our manuscript of “ID: water-538542, Raindrop Energy Impact on The Distribution Characteristics of Splash Aggregates of Cultivated Dark Loessial Cores (Laboratory Experiment)”. We have made revisions throughout based on the comments the reviewer 1. We hope that our responses to the comments and a significantly revised manuscript will satisfactorily address these concerns. Thank you again. If there are any other modifications we could make, we would like very much to modify them and we really appreciate your help.
1. Referee’s comment: 1. Abstract
The “Abstract” is well written. The structure is fine.
Author’s response: Thank you for your recognition.
2. Referee’s comment: 2. Introduction
I suggest to extend it with recent works available in literature dealing with the article
Author’s response: Thanks for your suggestion. we had done a revision and added some references . – see the text of revised file.
2. Hu, F.N.; Liu, J.F.; Xu, C.Y.; Wang Z.L.; Liu, G.; Li, H.; Zhao, S.W. Soil internal forces initiate aggregate breakdown and splash erosion. Geoderma 2018, 320, 43–51.
4. Xiao, H.; Liu, G.; Abd-Elbasit, M.A.M.; Zhang, X.C. Effects of slaking and mechanical breakdown on disaggregation and splash erosion. Eur. J. Soil Sci. 2017, 68, 797–805.
20. Hu, W.; Zheng, F.; Bian, F. The Directional Components of Splash Erosion at Different Raindrop Kinetic Energy in the Chinese Mollisol Region. Soil Sci. Soc. Am. J. 2016, 80, 38–44.
21. Wang, D.; Li, G.L.; Fu, Y.; Gao, G.X.; Zheng, T.H. Detachment and transport characteristics of sandy loam soil by raindrop action in the northern loess plateau, China. J. Soil Water Conserv. 2018, 73, 705–713.
34. Nash, J.E.; Sutcliffe, J.V. River flow forecasting through conceptual models 1: a discussion of principles. J. Hydrol. 1970, 10, 282–290.
3. Referee’s comment: 3. Materials and Methods
The photo or scheme of the experiment is missing
Author’s response: Thanks for your suggestion. we had done a revision and added the Figure 1. – see the text of revised file.
Figure 1. The test for splashed raindrops and soil aggregates (unit: cm)
Note: the figure is from Fu et al. [30]
4. Referee’s comment: 4. Conclusion
In this form, the conclusion should be in points
Author’s response: Thanks for your suggestion. we had done a revision. – see the text of revised file.
4. Conclusions
Dark loessial soil with Corg content of 1.6% and natural moisture 18.8% and core sizes (10x20 cm) were used in laboratory experiments. The main results are as follows:
(1) For each raindrop energy level, the mass percentage of soil aggregates > 2 mm is almost zero. As a whole, the mass percentage of particle sizes > 0.25 mm presented a down-up trend with the increasing raindrop energy and reached the minimum when the raindrop energy was 7.30×10-5 J m-2s-1. The enrichment ratio of aggregates presented an up-down trend with the decreasing particle size. A particle size of 0.25 mm was the critical particle size level for the enrichment and depletion of splash erosion. The macroaggregates were mainly broken into 0.25-0.053 mm aggregates in all rainfall experiments in the study.
(2) The splash erosion amounts of the six raindrop conditions (2.41×10-5, 3.68×10-5, 5.15×10-5, 7.30×10-5, 8.97×10-5 and 22.4×10-5 J m-2 s-1)are mainly distributed at distances of 0-20 cm (all investigated distances of 0-50 cm). The splash erosion amount (M) decreases exponentially with the increasing splash distance (S) (P < 0.01) for the same raindrop energy level. The splash erosion amount of the same splash distance has a power function relationship with the increasing raindrop energy (E) (P < 0.05). The nonlinear regression analysis showed a significant power-exponential function relationship among the splash erosion amount (M), raindrop energy (E) and splash distance (S).
(3) The fractal dimension (D) of the aggregates showed a downward opening parabolic relationship with the raindrop energy. The maximal raindrop energy value was 1.29×10-4 J m-2s-1, which broke the aggregates to the largest degree. The results provide insights into variation in aggregates in the soil layer during rainfall and understand the soil surface crust and soil erosion mechanism well.
4. Referee’s comment: 5. Language problems
The English language requires revision. There are quite many typos.
Author’s response: Thanks for your suggestion. we had done the revision for the manuscript. – see the text of revised file.
Author Response File: 
Author Response.docx
Reviewer 2 Report
water-538542
Title: Raindrop energy impact on the distribution characteristics of splash
aggregates (laboratory experiment with chernozem cores)
Authors: Yu Fu, Guanglu Li *, Dong Wang, Tenghui Zheng
Article has new experiments and can be publish after some editing.
Need change a Title: Raindrop energy impact on the distribution characteristics of splash aggregates of cultivated chernozem cores (laboratory experiment)
Need to expand the summary and conclusions.
In your study, you set the following 4 objectives, so you need to write in the summary and conclusion what results you received on these 4 objectives what object and methods do you use. ??
The objectives of this study were to (i) clarify the effect of raindrop energy on the splash distance 72 and particle size distribution of aggregate splash erosion, (ii) establish a prediction equation for 73 splash erosion in this area, and (iii) predict whether a certain raindrop energy will break up the 74 aggregates to the greatest extent by comparing the characteristic parameters of the aggregate 75 fractions.
14 (rainfall energy: 2.41×10-5-22.4×10-5 J m-2s-1 and 1.286×10-4 J m-2s-1,) at five splash distances
15 Need add: (from 0-10 cm to 40-50 cm). Соres of the size (10x20 cm) of undisturbed cultivated Dark loessial soil were selected in tree replicates as the research subject.
16 65.56-90.05% Need write 66-90%
and in all article will do the same and some data write as 1.2; 6.7 not 1,23, not 6,74
20-21 A model was obtained to predict the splash erosion amount for the rainfall energy and splash distance. In conclusion Need write if it possible to use your model for other soils and rain? And what differences between your model and models of other authors.
24 Enrichment ratio (ER). What does it mean?
24 values for fragments >1 mm were close to 0.
In results you discussed fragments >2 mm. not >1 mm
In table 1 Soil organic Need write Soil organic matter
From Fig. 1 you can see that the content of aggregates more than 2 mm in diameters in case of rains of different intensity is about 5-10%, and you write in the article. is 0%/ Raindrop energy / (10-4 J m-2s-1) Need write 10-5
271 For each raindrop energy level, the mass percentage of soil aggregates > 2 mm is almost zero (Need write amount of soil aggregates > 2 mm in natural soil before experiment).
In conclusion
Need write What soil do you use and it properties: Write as : sandy loam chernozem (dark soil) with Corg content of 1,3% and natural moisture???% and core sizes (??? cm) were used in laboratory experiments.
The splash erosion amounts of the six raindrop conditions (Need write which 1-6 conditions were used ) are mainly distributed at distances of 0-20 cm (all investigated distances of 0-50 cm). The splash erosion
Comments for author File: Comments.pdf
Author Response
Response to Reviewer 2:
Thanks a lot for the reviewer’ comments and these kind suggestions of our manuscript entitled “ID: water-538542, Raindrop Energy Impact on The Distribution Characteristics of Splash Aggregates of Cultivated Dark Loessial Cores (Laboratory Experiment)”. Those comments are all valuable and very helpful for revising and improving our paper, as well as the important guiding significance to our researches. The reviewer comments are laid out below in specific concerns have been numbered. The main corrections in the paper and the responds to the reviewer’s comments are as following:
1. Referee’s comment: Need change a Title: Raindrop energy impact on the distribution characteristics of splash aggregates of cultivated chernozem cores (laboratory experiment)
Author’s response: Thanks for your suggestion. we had done a revision. – see the text of revised file.
In the study, Dark loessial soil was used, which is a loess developed on the loess parent material, while chernozem is not the soil studied in this manuscript. Hence, we revised the title as follows:
L2-4: Raindrop Energy Impact on The Distribution Characteristics of Splash Aggregates of Cultivated Dark Loessial Cores (Laboratory Experiment)
2. Referee’s comment: Need to expand the summary and conclusions.
In your study, you set the following 4 objectives, so you need to write in the summary and conclusion what results you received on these 4 objectives what object and methods do you use. ??
The objectives of this study were to (i) clarify the effect of raindrop energy on the splash distance 72 and particle size distribution of aggregate splash erosion, (ii) establish a prediction equation for 73 splash erosion in this area, and (iii) predict whether a certain raindrop energy will break up the 74 aggregates to the greatest extent by comparing the characteristic parameters of the aggregate 75 fractions
Author’s response: Thanks for your suggestion. we had done a revision. – see the text of revised file.
L13-29: Abstract: To determine the effect of different rainfall energy levels on the breakdown of soil aggregates, this study analyzed the soil splash erosion amounts and the distribution of particle sizes under six rainfall conditions (rainfall energy: 2.41×10-5-22.4×10-5 J m-2s-1 and 1.29×10-4 J m-2s-1) at five splash distances (from 0-10 cm to 40-50 cm). Соres of the size (10x20 cm) of undisturbed cultivated Dark loessial soil were selected in tree replicates as the research subject. The results indicated that splashed aggregates were distributed mainly at splash distances of 0-20 cm, which accounted for 66-90% of the total splash erosion amount. The splash erosion amount significantly decreased exponentially with the increasing splash distance for the same rainfall energy (P<0.01). The splash erosion amount significantly increased in the power function relationship with the increasing rainfall energy at the same splash distance (P<0.05). A model was obtained to predict the splash erosion amount for the rainfall energy and splash distance. The fractal dimension (D) of the aggregates showed a downward opening parabolic relationship with the raindrop energy. The maximal value of the rainfall energy was 1.286×10-4 J m-2s-1, which broke the aggregates to the largest degree. Enrichment ratio (ER) values (Ratio of the mass percentage of splash sediment to the mass percentage of in the undisturbed aggregates) for fragments >2 mm were close to 0. A particle size of 0.25 mm was the critical particle level for splash erosion.
L309-342: 4. Conclusions
Dark loessial soil with Corg content of 1.6% and natural moisture 18.8% and core sizes (10x20 cm) were used in laboratory experiments. The main results are as follows:
(1) For each raindrop energy level, the mass percentage of soil aggregates > 2 mm is almost zero. As a whole, the mass percentage of particle sizes > 0.25 mm presented a down-up trend with the increasing raindrop energy and reached the minimum when the raindrop energy was 7.30×10-5 J m-2s-1. The enrichment ratio of aggregates presented an up-down trend with the decreasing particle size. A particle size of 0.25 mm was the critical particle size level for the enrichment and depletion of splash erosion. The macroaggregates were mainly broken into 0.25-0.053 mm aggregates in all rainfall experiments in the study.
(2) The splash erosion amounts of the six raindrop conditions (2.41×10-5, 3.68×10-5, 5.15×10-5, 7.30×10-5, 8.97×10-5 and 22.4×10-5 J m-2 s-1)are mainly distributed at distances of 0-20 cm (all investigated distances of 0-50 cm). The splash erosion amount (M) decreases exponentially with the increasing splash distance (S) (P < 0.01) for the same raindrop energy level. The splash erosion amount of the same splash distance has a power function relationship with the increasing raindrop energy (E) (P < 0.05). The nonlinear regression analysis showed a significant power-exponential function relationship among the splash erosion amount (M), raindrop energy (E) and splash distance (S).
(3) The fractal dimension (D) of the aggregates showed a downward opening parabolic relationship with the raindrop energy. The maximal raindrop energy value was 1.29×10-4 J m-2s-1, which broke the aggregates to the largest degree. The results provide insights into variation in aggregates in the soil layer during rainfall and understand the soil surface crust and soil erosion mechanism well.
3. Referee’s comment: 14 (rainfall energy: 2.41×10-5-22.4×10-5 J m-2s-1 and 1.286×10-4 J m-2s-1,) at five splash
distances
Author’s response: Thanks for your suggestion. we had done a revision. – see the text of revised file.
L15: (rainfall energy: 2.41×10-5-22.4×10-5 J m-2s-1 and 1.29×10-4 J m-2s-1)
4. Referee’s comment: Need add: (from 0-10 cm to 40-50 cm). Соres of the size (10x20 cm) of undisturbed
cultivated Dark loessial soil were selected in tree replicates as the research subject
Author’s response: Thanks for your suggestion. we had done a revision. – see the text of revised file.
L13-17: To determine the effect of different rainfall energy levels on the breakdown of soil aggregates, this study analyzed the soil splash erosion amounts and the distribution of particle sizes under six rainfall conditions (rainfall energy: 2.41×10-5-22.4×10-5 J m-2s-1 and 1.29×10-4 J m-2s-1) at five splash distances (from 0-10 cm to 40-50 cm). Соres of the size (10x20 cm) of undisturbed cultivated Dark loessial soil were selected in tree replicates as the research subject.
5. Referee’s comment: 65.56-90.05% Need write 66-90%
and in all article will do the same and some data write as 1.2; 6.7 not 1,23, not 6,74
Author’s response: Thanks for your suggestion. we had done the revision for the manuscript. – see the text of revised file.
6. Referee’s comment: 20-21 A model was obtained to predict the splash erosion amount for the rainfall energy and splash
distance. In conclusion Need write if it possible to use your model for other soils and rain? And what
differences between your model and models of other authors
Author’s response: Thanks for your suggestion. we had done the revision and added the Figure 2 and Figure 3. – see the text of revised file.
L215-242: For the M values, E values and splash distance S that were analyzed using multiple regression, the relationship followed a power-exponential function: M=E0.72·16.28exp(12.92·S-0.21), R2=0.81, P<0.05. The data of Wang et al. [21] was taken into the above equation for verification. The ENS value was 0.67 (Figure 2a). According to the verification analysis, an ENS value ≤1 or close to 1 indicated that the model was effective. It can be seen that the fitting was better, which may be because that the soil used in Wang et al. [21] was from the Loess Plateau and the rainfall conditions were similar to this study. The data of Cheng et al. [12] was taken into the above equation for verification. The ENS value was less than 0 (Figure 2b). This may be effected by soil types and slope. The data in this study were brought into the splash erosion model of Hu et al. [20]: ST=0.14KE2.65D500.54, where ST is total splash erosion (g), KE is raindrop kinetic energy (J m−2 mm−1), and D50 is the raindrop median volume diameter (mm).The results showed that ENS value was less than 0 (Figure 3), so the model of Hu et al. [20] cannot predict the amount of splash erosion in this study, which was mainly affected by soil types and rainfall conditions. The above research further indicated that the model proposed in this study can well evaluate the soil splash erosion in the Loess Plateau, but the simulation results of the areas outside the Loess Plateau are still insufficient. Therefore, the model correction needs further exploration in future research.
Figure 2 Comparison between the predicted and measured values of the splash erosion amount (a. data is from Wang et al.[21]; b. data is from Cheng et al.[12]).
Figure 3 Comparison between the predicted and measured values of the splash erosion amount.
7. Referee’s comment: 24 Enrichment ratio (ER). What does it mean?
24 values for fragments >1 mm were close to 0.
In results you discussed fragments >2 mm. not >1 mm
Author’s response: We feel sorry for our poor writings caused you trouble. Please see the text of revised file.
L26-29: Enrichment ratio (ER) values (Ratio of the mass percentage of splash sediment to the mass percentage of in the undisturbed aggregates) for fragments >2 mm were close to 0. A particle size of 0.25 mm was the critical particle level for splash erosion.
8. Referee’s comment: In table 1 Soil organic Need write Soil organic matter
Author’s response: Thanks for your suggestion. we had done a revision. – see the text of revised file.
9. Referee’s comment: From Fig. 1 you can see that the content of aggregates more than 2 mm in diameters in case of rains of
different intensity is about 5-10%, and you write in the article. is 0%/ Raindrop energy / (10-4 J m-
2s-1) Need write 10-5
Author’s response: We feel sorry for our poor writings caused you trouble. We had changed the color of the Figure 4 to make it clearer. Please see the text of revised file.
Figure 4. The particle size distribution of splashed aggregates for different raindrop energy levels.
10. Referee’s comment: 271 For each raindrop energy level, the mass percentage of soil aggregates > 2 mm is almost zero (Need
write amount of soil aggregates > 2 mm in natural soil before experiment).
Author’s response: Thanks for your suggestion. we had done a revision. – see the text of revised file in the Table 1.
11. Referee’s comment: In conclusion
Need write What soil do you use and it properties: Write as : sandy loam chernozem (dark soil) with
Corg content of 1,3% and natural moisture???% and core sizes (??? cm) were used in laboratory
experiments.
Author’s response: Thanks for your suggestion. we had done a revision. – see the text of revised file.
In the study, Dark loessial soil was used, which is a loess developed on the loess parent material, while chernozem is not the soil studied in this manuscript. Hence, we revised it as follows:
L310-311: Dark loessial soil with Corg content of 1.6% and natural moisture 18.8% and core sizes (10x20 cm) were used in laboratory experiments. The main results are as follows:
12. Referee’s comment: The splash erosion amounts of the six raindrop conditions (Need write which 1-6 conditions were used )
are mainly distributed at distances of 0-20 cm (all investigated distances of 0-50 cm).
Author’s response: Thanks for your suggestion. we had done a revision. – see the text of revised file.
L325-327: The splash erosion amounts of the six raindrop conditions (2.41×10-5, 3.68×10-5, 5.15×10-5, 7.30×10-5, 8.97×10-5 and 22.4×10-5 J m-2 s-1)are mainly distributed at distances of 0-20 cm (all investigated distances of 0-50 cm).
Author Response File: Author Response.docx
