Overall, this is a well-written, nearly complete manuscript. I have made numerous marginal comments and as well as specific comments keyed to the text below.

We will need to deal with scheduling both your defense and final draft submission. As you know, I leave May 9 for field work and every thing must be wrapped up by then. I should see one more copy of the thesis before I approve it, as should your committee. That next copy should be what you consider a "final" draft.

After you include everyone's comments and acceptence, make up one last draft that I'll sign. When you have signatures, please make at least two extra copies. One for the department and one for me. These should get bound by the library bindery. You surely want one bound for you too! There are less than three weeks before I get on a plane...so you need to move to get a draft to your committee as soon as possible. Please get back to me with a set of deadlines that will allow you to complete remaining work in time.

Looking toward the future, you should consider preparing an abstract for the GSA meeting in Denver. Deadline is early July for meeting at the end of October. Also, I think you should consider preparing a greatly shortened manuscript for publication. In particular, I think that the data relating to human impact and channel head types are important. Perhaps a journal such as Geomorphology? I can work with you to reduce the current document to something more manageable and help you get it into journal format. Perhaps this is something we could do over the summer? I don't think that it will take too long as your figures and tabel are prepared already.

Comments keyed to the text.

1. need official thesis cover page.

2. Can you come up with a corollary sentence explaining, in process geomorphology terms, why road plots have such large areas and lengths? You have this in the latter part of the text.

3. Before I see next draft, all references should be finalized.

4. Next draft needs all final figures and pictures.

5. Not quite parallel as no intensity is given for natural case.

6. Need to rewrite for clarity. when total driving force exceeds resisting force, soil will fail. Remember, pore pressure lowers resisting force by changing effective normal force.

7. AWK sentence, hard to follow. Rewrite of clarity.

8. IMPORTANT. I'm confused here...How do you do source areas for Type II channels when they have contributions from other channels? At best you can calculate minimum source areas. On the other hand, it is likely that subsurface flow through Type III heads is related to drainage basin area although not by overland flow (think about grwoundwater divides)...but I'll bet at the same time the subsurface was seeping, flow was pouring over the surface.

9. I'd choose another adjective...the data in the appendix don't support "closely" although the average is quite similar.

10. Awkward....again, what is saving you is a big "n" so that the averages are better. This means no bias between observers just lots of noise.

11. Tighten this whole paragraph up; it rambles and is longer than needed.

12. Need link here..the big drainage basins imply that areas remain unchannelized that will, in the future, see channels as the net work develops...so this implies headward development of the network..say so.

13. rejuvenated is an old and somewhat disfavored term...rework with incision...

14. I still don't really see the point of the equation but if you want it, then put it way up front as you suggest.

15. This sentence could be the link I was looking for in comment 12.

Sara Gran

April 20, 1999

Review of D. Santos thesis

This senior thesis involves studying channel formation in the

Mojave Desert. The presence of an abandoned military base provides Darrin

with a landscape that has been disturbed in several ways (by the presence

of roads and road berms and hard-packed walkways in the living areas) in

close proximity to undisturbed areas. Darrin compares channel

characteristics between these three types of surface (road, walkway,

natural), and also compares the channel initiation features in the arid

region to those found in humid regions. He concludes that, in his study

area, channels that form on the old roadways have larger source areas and

longer source basin lengths than those in undisturbed areas, probably

because these channels must be under 50 years old and possibly have not

had enough time to "stabilize." Channels on the walkways have smaller

source areas and shorter basin lengths than the undisturbed ones, probably

because the increased compaction on the walkways allows for more runoff.

He also concludes that the channel head morphology and the relationship

between source area, basin length and slope in arid regions does not

follow the same patterns as those in humid regions (where more work of

this nature has been done).

This is a good thesis draft that will benefit greatly from some

focusing. I often got lost and had to re-read sections because I couldn't

keep track of what the main points were. Good lead-in sentences will help

direct paragraphs. Some sections seemed to ramble, and will benefit from

some condensing and clarifying. Some sections, like that on statistics,

could be sent back into an appendix. The "Data Reduction" section of the

methods was difficult because I hadn't yet found out about the "Data."

Keep the methods section just about the methods--you have plenty of time

later to discuss the results on their own. All of the stats in the data

section made the data set seem to disappear--you could pull your Appendix

4 into your Data section and push all those nasty stats to the back.

This is a good early draft that needs work but has a lot of

potential to be a nice product of an interesting study. Some discussion

on why it might matter that the disturbed land has different channel

morphology would make this project more "relevant," and some more

discussion of why arid channel initiation is different than humid channel

initiation would be interesting.

Numbered comments

1. You need to talk about CHANNELS, not "plots." You aren't measuring

source areas in a plot, you are measuring source areas for channels within

that plot. Also, you could bring in some of the channel head morphology

into the abstract--that channel heads are different than in humid regions

and your explanation why.

2. Early on, you should define source areas and source basin lengths,

perhaps with an illustration.

3. awkward--re-word this

4. This is really the effects of human disturbance in general--in this

case you are dealing with a specific pulse of disturbance, but it's

applicable to all disturbance (bringing this in will make this whole thing

more general--not just tanks and soldiers can disturb a surface, but also

ATV's or whatnot).

5. Again, a illustration of these features would help (your "plot"

diagrams don't help).

6. Start each paragraph with a channel initiation mechanism and then

describe it. I got confused in here about what you were talking about.

7. Explain why you are spending so much time on humid channels, whereas

your study is arid. Isn't there any arid region research?

8. Make a diagram showing these relationships.

9. It gives you the opportunity to look at both disturbed and undisturbed

land, and you know exactly how that land was disturbed.

10. Again, I don't like the use of the word "plot," in here, it doesn't

immediately say to me "study area." But maybe that's just me.

11. How come you needed to use two survey methods?

12. Explain this better--unclear

13. never mind

14. You need to explain this more--what contours? Boundaries to what?

15. State up front what your data will be used for.

16. I don't like this paragraph--this is still a methods section and this

doesn't really feel like methods, either make it much more concise ("I did

a series of t-tests on the data to show whether basin lengths and areas

are statistically-different.").

17. Implies you could have something other than these two things...

18. You've just said this--redundant

19. I think this could be put into the appendix, you've already said that

you've done this.

20. I don't understand WHAT is significantly different--things between

different types of plots? Within plots?

21. All this talk about stats make your data get completely lost.

22. I don't understand what you are trying to say--is there or is there

not a relationship?

23. Consolidate your refs--they're all the same source, it seems excessive

to put it in there so many times.

24. Work on making this more concise and clear.

25. What is so important about a channel head being gradual or abrupt? Can

you use that to tell HOW channels are formed or what hydrologic processes

are happening? This paragraph is very confusing.

26. How does increased shear stress make shorter lengths and smaller

areas? Is the area actually SMALLER? It's getting runoff from a larger

area, right?

27. This seems more suited for a "previous works" section.

28. Have you mentioned this channel destruction stuff elsewhere yet?

Seems fairly important and should be somewhere in the introduction (the

landscape within the camp is disturbed--by having these roads and walkways

which obliterate channels and change local slopes and compaction and

roughness...)

29. I have a hard time understanding what all this is saying...