Nichols, K. K. and Bierman, P. R., Fifty-four years of ephemeral channel
response to intense military activity at Camp Iron Mountain, Mojave
Desert, California
The authors surveyed in great detail several tracts of land on a
desert piedmont surface to assess any lingering geomorphic effects from
two years of intense military training 55 years ago. Their data suggest
that the shallow ephemeral channels common to this area were disturbed at
the onset of military training and have still not regained their
pre-disturbance character. In particular, channel widths, depths,
cross-sectional areas, drainage densities, and areas remain different in
disturbed plots of land as compared with control plots.
The authors present convincing evidence that the effects of
military training 55 years ago linger today, and will likely persist into
the future. The writing is clear and concise, with only a few grammatical
errors as noted. The diagrams are helpful and easy to understand, with a
minor exception or two (again, noted on the manuscript). Their data appear
to be thoroughly collected and thoughtfully analyzed, although the
standard deviations of channel measurements commonly approach 75% of the
mean value, and often overlap with the standard deviations of measurements
that the authors mean to distinguish. Therefore, although the differences
in channel character are distinguishable, they are often small.
I recommend this paper for publication with the revisions noted.
These suggestions mostly concern grammar and punctuation, and are noted on
the manuscript. My comments for major revisions or further thought are
provided below, and are referenced by number to their location of concern
in the manuscript.
1. The word "plots" is used lots in this paper. It would help to
define this term not solely with respect to the different varieties of
experimental types of plots you used for this study. A brief statement in
the methods section that makes clear their designation for a tract of land
of a certain size would help the reader.
2. Although the title clearly states that the focus of study is the
nature of ephemeral channel response to military training, the
introduction states the importance of a broad understanding of geomorphic
disturbance and response to military exercises. Some explanation, then,
should be given for the focus solely on channel character in this study.
What other geomorphic disturbances occur as a result of military training?
Why is the channel character of paramount importance here? For example,
soil compaction and surface smoothing are discussed later in this paper.
Some mention early in the paper that they and any other effects result
from military training would improve the paper.
3. Might these categories of plots introduce any kind of bias to the
data? The paper would be improved by an explanation for why plots were
divided into these three categories for this study. We can only assume
that the remains of the camp may be similarly divided (visually).
Review of Nichols and Bierman
This paper outlines the effects of military activity from 1942 to 1944 on
the channel morphology of a desert piedmont surface in the Mojave Desert
of California. The study has compared three different types of land use
at the Army camp in order to determine the effects of each type of
activity: walkways, roads, and control sites that were untouched by camp
activities. It is shown that the natural channel system on the piedmont
slope has largely been unable to reestablish itself within the military
camp area. Walkways, which had been outlined by small rock walls, have
diverted water flow on the piedmont surface causing channels to be
narrower and shallower than natural channels in the control areas.
Walkway channels also tend to be discontinuous and have a high drainage
density. Road berms have also redirected water flow on the piedmont
surface, creating a 20-40m zone of sheetwash down gradient of the berm
with most runoff dispersing into braided channels at breached berms or
along roads that are parallel to gradient. Increased stream power,
discharge and sediment yields have resulted from the compaction and
smoothing of soil on the piedmont surface. Nichols and Bierman suggest
that removal of road berms and walkway rocks would aid the rehabilitation
of piedmont channels, although the consequences of soil compaction and
smoothing may last for tens of years.
In general, I found the paper to be very well thought out and clearly
presented. Methods are carefully reviewed, and the data is presented both
verbally and visually to aid reader comprehension. The data correlate
well with the reported field observations and final conclusions. All
calculations are presented with their corresponding equation sets and
error margins. The writing was well-organized and easy to follow. Some
parts of the paper were a bit choppy and/or redundant, however, I believe
that some minor edits could resolve that problem. Also, some details
could be better explained (see manuscript notes). Tables and figures were
clear and straightforward - I was able to quickly gather information from
most of the tables and figures. Only one figure seemed out of place and
unexplained in the text (note #9 in the manuscript). A few typos are
present throughout the script.
I would recommend this paper for acceptance with only minor edits. The
paper presents timely evidence for the effects of human impact on
landscape development and provides information that will assist in future
remediation of such sites. I feel that the topic will be of interest to a
large audience. Additionally, it is a strong paper with a clear portrayal
of current channel activities at Camp Iron Mountain, and is written with
an attention to detail and a clarity that makes it accessible to readers
from a diversity of scientific backgrounds. The data sets are complete
and well represented in the accompanying tables and figures.
Manuscript:
1. I think this sentence would work better as a beginning sentence - i.e
as the first sentence of the paragraph. It's a strong sentence that would
make a good impact at the beginning of the paragraph.
2. I just wondered why the army had constructed the berms and walkway
outlines - was it for navigation only, or to also divert channel drainages
away from the camp?
3. In this paragraph, you say that most of the precipitation is being
infiltrated, then in the last sentence you say that only some of the
overland flow is being infiltrated. I find that a bit confusing.
4. How deep does sheetwash generally need to be to prevent incipient
channels from being obliterated by raindrops?
5. I just wanted to mention that I switched 'training' to 'usage' because
it sounded like the stream had undergone military training. Also, the
hanging "54 years ago" at the end of the sentence seems very out of place,
although I don't know how to better rewrite that.
6. You haven't mentioned anything about the size or area of the study
plots - do they all have the same area?
Also, it might be helpful to the reader to mention an average channel
width for control streams, since you mention the depth several times.
A more thorough explanation of why the plots were chosen as they were
would be helpful. It is obvious that you went through a lot of effort to
standardize the plots, but what was the basis for those standards? For
example, why did all of the road plots need to be free of rock alignments?
Was it to be able to view the effect of each type of structure alone? If
so, then say it!
7. Figure 3 - I don't understand what "abundance" represents.
8. "The average drainage density for the walkways inside the walkway
plots..." I'm confused - do you mean the density of streams that have
formed within old walkways? And does that mean you are ignoring any
streams that are in the plot but did not form in walkways for this
calculation?
9. How does Figure 5 fit into the text here? You don't discuss it at all.
10. On page 8 you say that the control plot stream channels have the
largest range of orientations, but here on page 9 you say that they have
little deviance in orientations. So which one is it?
11. The underlined sentence seems out of place since the previous
sentence discusses the rock barricades. It might be best to start a new
paragraph here, using the underlined sentence as the first in the new
paragraph.
General note: I had a hard time visualizing how road berms were affecting
channel flow from reading the text.
The paper by Nichols and Bierman presents survey data gathered in and near a military camp abandoned over 50 years ago. The data characterize the small-scale drainage network and demonstrate that human impacts on the landscape can still be detected in measurements of average channel width, depth, area, and drainage density.
Overall, the paper is complete and reasonable presented. It would be greatly strengthened by the addition of statistical verification of population seperability. The process model section could be condensed as it is repetitive of the text in places. The text needs minor clean-up including correction of the page 1/page 2 transition and line spacing. There are numerous minor marginal comments on the ms.
Final recommendation, publication after revision.
1. Title needs a time reference so as to indicate activity is not ongoing.
2. No sense at end of page 1.
3. On figure 1, need to show camp.
4. Figure 1A needs lat., long, and scale.
5. This sentence is the place to introduce, succinctly, the test of means difference using t-test.
6. Condense to one sentence, these are redundant.
Critical Review of Nichols, "Fifty-four years of ephemeral channel response to intense military activity at Camp Iron Mountain, Mojave Desert, California."
Nichols "Fifty-four years" describes the affects of the U.S. Army's presence in Camp Iron Mountain (Mojave Desert, CA) on the re-establishment of ephemeral channels fifty years after the camp was abandoned. Nichols studied three types of plots including two types of experimental plots (road and walkway) and a set of control plots. The military's presence and alteration of the landscape has not allowed the ephemeral channel network to fully recover to 'natural conditions' (as illustrated by comparison of control and experimental plot data). Channel depths and widths are smaller in experimental plots and the channels are more discontinuous than control plots channels. Control plots have the highest drainage densities. Local drainage divides set in place by the military, such as rock alignments and road berms, have changed channel flow patterns in experimental plots forcing flow against the natural gradient and leaving areas 20-40m without channeled drainage. Nichols also explains the results of previous studies that focused on humans (military and ORVs) smoothing surface roughness, reducing infiltration, and compacting desert soil. Nichols links existing data to his findings by showing that these factors are present in the experimental plots due to the presence of the military. Nichols shows that these factors also influence the discrepancy between control and experimental plots.
Nichols thoroughly explains how he collected the data, presents the data clearly, and provides logical explanations about the data. Nichols seems to have a sufficient amount of data (i.e. topo points, plot numbers, and variation in plot locations) to make generalized conclusions about the entire camp. The control plot data, even with a large variation in location on the piedmont, supports that the piedmont is uniform (and therefore a 'true' control). Nichols backs up his general conceptual interpretations by citing well known, reliable sources in geomorphology (Horton, Dunne and Leopold). Nichols also cites more recent source that have studied the affects of humans in arid regions and links these sources to his study. Nichols illustrations complement the data and explanations well. The rose diagram of channel orientations is a very strong figure! The air-photo of plot locations also sets a lot of things in perspective. I do have a few recommendations for figures, which are listed below.
I believe that Nichols paper should be accepted for publication simply because it is an original study conducted in unique area where the military's impact on small-scale geomorphology can be studied. Not only does Nichols have an interesting data set, but he also does a good job of explaining of how the military has affected the recovery of the channel network. I do recommend this paper (in its current form) for publication, however I am not sure what the editors of Environmental and Engineering Geology Impacts on Military Operations are looking at for publishable work. Nichols does not explain why the military should care (or why anyone should care) about what persisting affects that Camp Iron Mountain has caused to the recovery of the channel network. I can understand that the presence of the camp has altered the channel network morphology (which is interesting, hence making the paper worthy for publication somewhere), but does that have far-reaching implications that the editors of Env. and Eng. Geology Impacts on Military Operations will be concerned with.
Specific Comments:
1. Add specific data/numbers here You use numbers elsewhere in your abstract, it will make it more consistent.
2. This refers to Figure 1B. You mention the camp in the text yet it does not appear on figure 1B you could add it by just drawing a square on the existing figure. It will help to further place fig 1C into perspective and to explain how the camp roads are placed sub-parallel/perpendicular to the natural gradient.
3. This is the point in the paper when I noticed that you jumped between the uses of runoff and overland flow. Do they have the same meaning? In the next paragraph you explain sheetwash this helps, but define/differentiate between runoff and overland flow.
4. Mention that a computer contoured the data and mention the program software I think Surfer is known as one of the best for interpolating topography.
5. Would measuring two channel orientations for channels with curvature make any sense or is averaging the orientation the way to do it. I feel that measuring two (or three) orientations might better represent what is really happening.
6. This refers to figure 3. Is there any significance to the fact that all the plots are skewed to the right?
7. In your Data Section (under channel orientations) you mention control plots have the largest range of orientations, yet here you mention there is 'little deviance'. You should reword this a little bit to make it sound less contradicting. And also mention that the control plot channel orientation is very close to the piedmont average gradient the connection is not spelled out in the text and I think it is an important one.
8. How did you estimate that 'more than half of the road berms and walkway alignments are still intact'. I'm a little confused here have half of these disappeared in fifty years?
*** Two general comments. 1. Mention the previous studies on surface
roughness and soil compaction earlier (in the intro) the first mention of
these results comes on the 9th page. The text will flow better if you mention
these (just briefly) studies earlier in the paper. 2. Mention that over
ten other camps existed in the Mojave that all are probably experiencing
the same implications by having road berms and rock alignments present.
"Fifty-four years of ephemeral channel response..." by Kyle
Nichols discusses the recovery (or lack thereof) of desert surfaces
following a short-term, intense disturbance of the landscape caused by
military manuevers during World War II. The surfaces in question are a
bank of coalescing alluvial fans forming a piedmont surface in front of
the Iron and Granite Mountain ranges in the Mojave Desert. Specifically,
Nichols looked at the size, distribution, and orientation of shallow
ephemeral streams in both disturbed (containing either roads or walkways)
and undisturbed areas on the piedmont surface. Channels in the
undisturbed regions are wider (by nearly a meter) and deeper (by just over
centimeter) than the channels in the disturbed areas. Disturbed areas are
also more likely to contain channel heads. Roads and walkways also affect
the orientation of channels (channels tend to prefer flowing along a road
or walkway almost as much as flowing directly down-gradient).
This paper should be accepted for publication in "Environmental
and Engineering Geology Impacts on Military Operations," after the author
addresses some minor issues (discussed in detail below), and the more
major issue of the redundancy of the "Process Model," section of the
Discussion. The author makes it very clear exactly what data were taken,
how those data were treated, and does not try to overstep its own bounds
in coming to any speculative conclusions. My only really major problem
with this paper is the seemingly-inefficient manner in which the author
presents results and then repeats many of those results in the discussion.
A final minor problem I had with this paper is that none of the desert
process references are younger than 10 years old--I do not pretend to have
any idea about what the desert geomorphology literature is like, but it
would seem that someone would have been working on similar topics within
the last 10 years.