Hydrogeology of Volcanic Highlands Affects Prioritization of Land Management Practices

Round 1

Reviewer 1 Report

Manuscript 910716 aims at understanding the interlinkage of geology, hydrology and effectiveness of LMW practices in Ethiopian highlands with Gomit watershed as an example. While the manuscript is well written, there are many confusing phrases, poor grammar, and unclear facts that should be made clear. The manuscript may benefit from a through check of grammar and expression.  Abstract should state briefly the purpose of the research, but important details must be included. The paper needs to be checked for consistency of units in texts and graphs. Discussion must explore significance of the results of work without repeating them. Overall, the paper needs a major revision.

Below are my specific comments

1. Line 14: 40%- spacing or no-spacing; be consistent
2. Line 16- What are amelioration practices? Define
3. Line 16- A field experiment is grammatically wrong. a field experiment or many experiments?
4. Line 17- mention Gomit watershed somewhere
5. Line 18- add comma after basalt. What % of rainfall? Provide value
6. Line 19- How much is much less runoff? Provide numeric value
7. Line 22- Add comma after loss
8. Line 40- Provide example of sound engineering methods. It could be mentioned inside parenthesis
9. Line 44-46- Are these field experiments or modeling?
10. Line 48- Rewrite the sentence "Another problem...". Transition problem.
11. Line 49- Are clay in andosols found under volcanic rocks?
12. Line 55- The current study is- change "is" to "was"
13. Line 63- Briefly describe the LWM practices
14. Line 70- Land and water management in all cases depend in climate. Nothing new. Rewrite this sentence
15. Line 72- rainfall storage in soil- what depth? surface storage? vadose zone?
16. Line 73-what is the significance/implication of P>PE?
17. Line 75-hydrology or hydrogeology?
18. Line 76-79- This sentence "In addition.." does not flow with last sentence. Move this sentence before "None of these...." DO these studies addressed the underlying hydrology or not?
19. Line 82- soil loss value does not seem correct. Check the data
20. Line 88- Rewrite your objective to make it crispy clear
21. Line 104-107- change was to is
22. Line 104- For mean annual rainfall, evaporation, i believe you can say the unit in just mm. Check recent papers to confirm
23. Line 140- when were trees planted, in 2006?
24. Line 143- are reported not were
25. Line 156-158- scientific names must be in italics
26. Line 167-168- give company name. what is the precision?
27. Line 171-How was infiltration measured? Did you clear organic matter from soil? was it hammered into the ground? what is the dimension of the ring? How frequently was the reading taken? How long was the infiltration carried out?
28. Line 182-fluctuation in water table?
29. Line 185-so the perched aquifers are at nearly 500 cm depth? if so need to indicate that
30. Line 189- what sort of weir? v-notch?
31. Line 203- How was the water sample handled in field? kept in cooler?
32. Line 207- Provide reference to the method
33. Line 228-what software package was used? Did you calculate it manually?
34. Line 230- descriptive stat in excel?
35. Line 234- Please check recent papers? do they report it as mm or as mm/yr
36. Line 244- check units
37. Line 255- define PE in data analysis section
38. Line 310-move this sentence to methods section
39. Line 329- annual discharge or do you mean runoff?
40. Line 329- 80 mm discharge or depth? Discharge is usually in cfs. SO do you mean flow depth?
41. Line 395- ..transported out...-did you observe this? Or is it what you think?
42. Line 441- Move hypothesis to introduction section after objectives
43. Line 456-what is runoff coffecient? Define it in the method section
44. Line 488- provide reference after "published watershed studies"
45. Line 512-discuss why sediment yield is high in agricultural land compared with forest
46. Line 516- confusing. do sediment become limited in later months or in July?
47. Line 532-to increase or to decrease. I believe when inflitration increases, runoff decreases
48. Line 534- How about time to runoff start? do LWM slow time to runoff start?
49. Line 563-discharge or runoff depth?

Author Response

Dear Reviewer

Thank you for your extensive comments.  We incorporated all suggested changes in the revised manuscript. Please see the attached pdf for details. The marked-up manuscript is appended at the end. All changes are in blue font

Apologies for the misprint in the manuscript. We checked the revised manuscript thoroughly for misprints, Hopefully only a minimum is left

Best wishes

For all authors

Tammo Steenhuis

Author Response File: Author Response.pdf

Reviewer 2 Report

The paper is an interesting case study of highland catchment in Etiopia where the runoff and sediment losses were studied for three years. 

The introduction section is well developed although the authors stated that L43" in the volcanic highlands, discharge is affected directly by the age of the geological formation". This is my opinion not always true, the discharge is proportional to the topographic slope and to the hydraulic conductivity of the unsaturated and saturated zone. The latter is directly linked to the degree of fracturing of the volcanic rocks and to the fractures network (interconnected or isolated). This concept must be better explained by the authors.

In the materials and methods the rainfall has been recorded by only one station but since the elevation of the watershed is variable how the authors have account for variations induced by altitude is not clear and should be explained in the revised version.

The double ring infiltrometer is preferred to single ring, please add the uncertainties linked to this method respect to the double ring.

Water velocity in the weirs should have been measured with a flowmeter, please highlights the limitations of the hand method used respect to state of the art methods.

Please add the uncertainty as standard deviation of Sediment concentrations including the errors in flow estimation. This should be also shown in table 3 and in figure 10 as error bars.

In the discussion section the authors stated that L559"Since the volcanic highlands seem to function similarly to other highlands in the world, our result should be valid outside Ethiopia as well". I do not agree, you should provide numerical simulation to proof this concept via for example SWAT model.

In the conclusion section the authors stated that L566"This loss of water was through faults and appear likely as spring at the lower elevations in the Tekeze basin." But this cannot be proofed without environmental tracers or other hydrogeological information.

At L 568 please express the sediment yield in tons per hectar per year.

The last sentence is too generic since we have more the 70 years of research on soil loss e.g. USLE and RUSLE due to factors like geological formations.

Author Response

Dear reviewer 2

Thank you for your extensive comments.  We responded to all your comments and implemented the suggestion in the revised manuscript. The detail is provided in the attached pdf. The marked-up manuscript is included in the pdf.

Thank you again

For all authors

Tammo Steenhuis

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

N/A

Reviewer 2 Report

I think that the authors have correctly modified their manuscript accounting for the requested changes thus the paper is now ready to be accepted for publication.