Spatial Variability of Preferential Flow and Infiltration Redistribution along a Rocky-Mountain Hillslope, Northern China

Round 1

Reviewer 1 Report

Comments and suggestions for Authors are given in an attached file.

Comments for author File: Comments.pdf

Author Response

Please see the attachment.

Author Response File: Author Response.docx

Reviewer 2 Report

The article describes realization of the extensive field experiment in which a spread of infiltrating water

within a stony soil of sloping rocks of Taihang Mountains in northern China has been measured.

The use of two types dyes (BBCFC and KI- starch) and the set-up of optical measurements enabled to

interpret the observed water spread process in terms of preferential flow indices and spatial

non–uniformity of infiltration redistribution.

Indices of longitudinal and orthogonal water spread indices have been linked statistically with

geomorphological characteristics of the soil. SPPS free software has been used for the purpose.

Altogether I consider the experimental method proposed by the Authors as novel and the way

of interpreting the results essentially scientific.

However, the presentation of details of experiment could be made slightly shorter. Although

a contents of larger and fine fragments of rock (and thus the measure of preferential and dispersive

spread of water) are highly correlated with the rock slope, too frequent use of word “slope” in the text

may made the reader impression that gravel and clay content are just only two of many soil

parameters. Instead, the gravel and clay content are the major direct causes of two types of water

spread occurring in soils. This aspect of physical dependence should be emphasized in the article

a little bit more.

As the article present novel idea and good scientific level I suggest to print the article after slight

modification of the text according to the above suggestions and with some shortening

of the description of the experiment set-up.

Author Response

Please see the attachment.

Author Response File: Author Response.docx

Reviewer 3 Report

Dear Authors,

Presented article present interesting topic about flow in complex geological medium. However I have some doubts about main idea of this article.

Authors suggest, that position in the slope can make effect on flow direction and shape of infiltration. They test this thesis on five places on one slope. In table 2 they show soil properties, which mainly are different for each point. They mainly increase or decrease with slope position (except A-B). Value of these parameters and local heterogeneity has main effect on flow and infiltration. So, in my opinion, correctly question should be: how geological processes (local geology, mass moves, weathering, etc.) influence to value of soil parameters along the slope (position in slope). And after recognize main source of these variation, can by consider their effects on infiltration. In presented form, only one factor, extremely local,  was consider.

The second main  charge is about conclusion. Please clearly describe how these conclusions can be used.  have no idea how it could be implemented / use in interpretation, f.e. in numerical modelling. It is only local disturbation of flow. OK, science not always must be practical, but few sentence about practise aspect should be add.

Below some minor comments.

In presented paper there is no information about geological history of this slope. There is only too simplistic cross-section. If infiltration depend on distribution gravels in soil, maybe 3D plots with their position and approximate size or photo of typical profile for each plot A-E. Photos are made for image analysis, so it will be easier (maybe after small interpretation – contours, etc).

   On figure 6 legend is wrong. On plots are two dashed and two solid line, with circles and triangles. In legend are 3 solid, and only circles.

What means range in table 3. Normally range is described by two numbers <low, high>. Please define range..

Also in table 3 and table 5 please consider horizontal line in middle of table to separate data for two sets (orthogonal and parallel, BBFCF and KI-starch respectively)

I can’t find information about with size of boxes δ are used for calculation of fractal dimension. Please add this information.

What is “F” on fig. 4a?

Two important parameters of flow (porosity and hydraulic conductivity) are rarely correlated with coefficient of preferential flow. Please add comments about it.

Also please add explanation of coefficients symbol in table 5 (like soil paramaters).

Last remark, please add in table 2 contribution elements with particle size >2mm [%]. Even in form as a difference between 100% and sum of mean less particle size.

Author Response

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Author Response File: Author Response.docx

Round 2

Reviewer 3 Report

Mostly corrections are OK.
small remarks above:

p. 15 (note below tab.3) - "defined as the subtraction of the
maximum of Cμ and the maximum of Cμ ";
I suppose the second "maximum" should be change into "minimum"

And I still can't find in manuscript text definition "F" letter in fig. 6a, if variables are only A-E (Fe, Fde, EFd). Not capital, not small, but "F".

Author Response

Response to Reviewer 3 Comments

Thank you for your thoughtful suggestions again! We have taken every comment seriously and made correction which we hope to meet with your approval. The following is one-by-one response to each request.

1. p. 15 (note below tab.3) - "defined as the subtraction of the maximum of Cμ and the maximum of Cμ ";I suppose the second "maximum" should be change into "minimum"

Response: Thanks very much for your greatly helpful suggestion. We have corrected as required.

2. And I still can't find in manuscript text definition "F" letter in fig. 6a, if variables are only A-E (Fe, Fde, EFd). Not capital, not small, but "F".

Response: Thanks for your comment. We are sorry that the explanation in the last response letter failed to answer your doubt. As you can see in the text, the experiments were conducted in 5 plots under 2 treatments, which means 10 groups of data could be obtained for each preferential flow index excepting for PF-fr and stable infiltrability. The differences of these 10 groups of data were analyzed due to the necessary of the comparison of the results from different treatments as well as different plots. The results of the difference (p < 0.01) between 5 plots under 2 treatments exhibited 6 levels, which were denoted as A-F on the boxes in Figure 6 Page 12. Therefore, there is no relationship between the letters (no matter capital or lowercase) on the boxes and those under the abscissa axis. For example，the “Fe” on the box of A-BBFCF was different from the “DEc” on the box of A-KI-starch in Figure 6a, indicating that there is a highly significant difference (p < 0.01) between the total dye coverage of A-BBFCF and A-KI-starch.

In order to avoid misleading, we have corrected “ Capital letters above the box indicate highly significant differences (p < 0.01) between the corresponding variables among experimental plots A–E, whereas lowercase letters indicate significant differences with p < 0.05” into “ Capital letters above the box indicate highly significant differences (p < 0.01) between the corresponding variables among experimental plots A–E under 2 different treatments (10 groups for each preferential flow index 10 groups for the preferential flow index in Figure 4a-c), whereas lowercase letters indicate significant differences with p < 0.05” in the Figure 6 Page 12.