Quantification of the Evaporation Rates from Six Types of Wetland Cover in Palo Verde National Park, Costa Rica
, Catalina Esquivel-Vargas 2, Miriam Coenders-Gerrits 1 and Mahmood Sasa-Marín 3Round 1
Reviewer 1 Report
The work on quantification of the evaporation rates of six wetlands covers is interesting to know the effect from this plant to the water fluxes. I have carefully read your manuscript and I think that the manuscript is generally well written. However, still required a moderate revision to improve the work before the publication.
Introduction
1. The introduction is a lack of information,
- about evaporation effect in literature. Especially about the aquatic plants in this area and the plants have been used in this study.
- about the methodologies have applied in the literature and why did you use the lysimeter method
2. Could the authors give a brief explanation of macrophytes in one or two sentences (with respective to line 29)
3. Could the authors briefly explain at the end of the introduction for what the results would be helpful?
4. Line 14: Results indicate (check the grammar)
5. Line 25: Please introduce the abbreviation “RAMSAR”
6. The authors have used the word evaporation instead of evapotranspiration which contains several components. In this study plant transpiration play an important role and if the authors compare the evaporation from wetland covers with an open water body, these two components have a different meaning by evaporation. Therefore, throughout the paper, it should be clearly mentioned that which component you are referring to. Eref in Penman-Monteith equation (Allen et.al 1998) stated as latent heat flux referring to evapotranspiration. Additionally, the energy equation that have generally been used also referring to evapotranspiration. If the authors use the same concept, consider keeping the same wording to avoid confusions.
Material and methods
7. There is a lack of information about manual data collection. How the excess water and storage change were measured?
8. Some information are missing in the method section such as how deep the water level at the natural habitat of each species, plant height, root system etc.. Maybe those could be added to the table 1 or separately.
9. Could the authors explain how reasonable to develop the growing environment of these plants inside the lysimeters? Does the growing environment of the plants are exactly representeded inside the lysimeter? It is not clear that the conditions inside same as in the natural habitat of each species.
10. Was there any irrigation?
11. Were the lysimeters bottom sealed?
12. Could the authors reasoning the comparison of Eref and E which are calculated by two different equations based on different parameters?
13. Could the authors mention the equation numbers which he used from the original paper (Allen et al 1998) and to calculate the other relevant parameters.
14. Please mention the values you used to calculate eq.1. Maybe in a table or mean value with standard deviations for the experimental period.
15. Authors have added the latent heat of vaporization and water density additionally to equation 1 and could the authors explain the reason.
16. Statistical differences between the evaporation from 6 wetlands are not reported. For example line 188, 209.
17. Line 87: Stronger compared to what? Could the authors add value here?
18. Line 94: To what “Lower mountains“ refers to? Could the author give a value of the height of the mountain?
19. What kind of a plant is Eichhornia crassipes? Could the authors describe that with other plants (lines 100-104)?
20. Line 108: Better, write as “beginning of the dry season” instead of “during” because your experimental period was only at the beginning of the dry season.
21. Line 114: How many plants from each species in the mixed unit contain? Is it a random collection? This information is not clear.
22. Line 124: Please restructure the sentence and check grammar.
23. Figure 4: Is the shape exactly rectangular? It does not look exactly rectangular in figure 4 (photo). Please draw the correct shape of the lysimeter.
24. Please add “right image” for the right figure in the figure caption.
25. The subtopic Data collection contains data collection and evaporation estimations. Therefore, better separate them.
26. Line 137: es and ea are not described.
27. Line 146: Could the authors mention which value was used as the precipitation. Just from the one event on 27th December? Please explain.
28. Line 148: What is E0?
29. Line 158, 160: Please introduce the abbreviations LSD and WRPLOT.
30. Line 169: Figure or Fig. ?
31. Fig 5: Please indicate the data source in the figure caption.
Results
32. Authors should pay more attention to highlight the main results in this section.
33. Fig 5: Please mention the data source.
34. Table 1: Please specify for what a,b,c are referred to.
35. The Authors have included the wind speed in figure 5 and therefore figure 6 is not necessary. Leave only the information in line 170-171.
Discussion
36. The discussion is not strong enough to wrap up the conclusions. The evaporation values from different wetland covers are not compared with the literature and how those have been affected by the climatic changes are also missing. Because the authors are focusing more on climatic variables, the effect from those on the evaporation was less discussed. Therefore restructuring is required.
37. Last paragraph in the discussion (line 251-257): Benefits of calculating the crop coefficient on evaporation was not clearly mentioned. Authors have only mentioned that it describes evaporation (line 254:255), which is not sufficient.
38. Line 206-207: There is a mismatch with lines 198-200. “Nep–nat and Eic–cra are influenced mainly by radiation and temperature conditions” “Nep–nat evaporation is poorly correlated to air temperature …” Please discuss the based on your results.
39. Line 210: Could the authors explain how did they come to this conclusion? It is also not clear what “these covers” refer to.
40. There are accumulated evaporation values in table 1. However, it is not mentioned how did these values obtained in the methodology.
41. Line 211: What do the authors mean by “other once”?
42. Based on what did you build up the sentence 211-212? The correlations are not reported.
43. Line 215: Did the authors identify any differences in stomatal conductance between the plants?
44. Line 218: <20 cm is from the surface water level? Please mention clearly.
45. Line 223: Nep-nat and Eic-cra are named as wetland covers. How does it compare with “wetland covers” again?
46. Line 234: Typha sp.species check if this is correct.
47. Line 236: How does the age apply to your studies? Could the authors mention what kind of plants have you had in your experiment in the discussion?
48. Line 242-243: Same reasons were addressed two times in this sentence. Not clear enough.
49. Line 245: What kind of effects can occur on water hydrology? Please specify.
50. In conclusion, the authors should only discuss their findings. The authors have mentioned root system, plant biomass and plant heights in the conclusion but have not mentioned in the results section. Better restructure it.
Author Response
Thanks for your review. See the reply in the attached file.
Author Response File: 
Author Response.pdf
Reviewer 2 Report
Overall paper can be improved. Please, find my comments with attached file.
Comments for author File: Comments.pdf
Author Response
Thanks for your review. See the reply in the attached file.
Author Response File: Author Response.pdf
Reviewer 3 Report
The principal novelty in this paper is the results of evapotranspiration for plants in the tropics. This is new. The methods are good and traditionally employed for evapotranspiration determinations, however the statistical anaylisis have to be more clarify. The results have a good presentation although they can be improved, specialy figures. However, I feel that disccusion was poor, basically for two reasons: a) the references are old. You have 57 references but only 20% of them are from the last 5 years. In your literature review, Don´t you find any interesting data in the last 5 years for comparison to your results?. That is strange for a scientific paper. b) I belive that authors lost a huge opportunity to make some recommendations on management of vegetation in the national park, specially in the potential water loss due evapotranspiration during dry season. They said something in the last paragraph but you can give more recommendations related to management for other national parks or something more. I think the paper has to be check by the authors and references must be update.
More specific comments of your paper:
Line 10: ¿Why the monitoring time was very short?.
Line 15: You say "...statistically diferent...", however you don't use any p-value. Please add.
Line 19: I suggest use keyword "Costa Rica" instead of " Guanaste". For me is more common and easy to find Costa Rica instead of Guanacaste.
Figure 2: Please improve. This Figure is very difficult to read and the figure caption is too extensive. May be you can use another way to represent the data and the simbology has to be put inside figure.
Line 106 to 120: Please you have to say that you use 5 replicates in your experiment design. I found this information in results.
Figure 3, caption: "Selected experimental units....". I suggest use the word "plants" instead of "units", because in your figure you try to show the plants not lysimeters.
Figure 4: you put this figure in your paper, but in the previos paragraph you didn´t mentioned in all.
Line 132-142: you explain the parameters for equation 1, that is good. However, you don´t tell me the specfic values used for your calculus. Please add.
Line 148 and Equation 3: In this line you wrote "Eo", however in equation 3, I see "Eref". Are you talking about the same?.
Line 154-155: You use anova for significant analysis. That is possible. However, ¿Are you sure that your data are normally distributed?". Did you use test for check the normality?. You didn´t tell anything about that. I think is possible use another test for comparison for non-normal distribully data. Please support the use of anova. I have another doubt, If you use 5 replicates, ¿What statistical test do you use for the homogenicity of the replicates?. You didn´t tell anything about that. Please add.
Line 157: "p = 0.05", I think you are talking about the significance level. However in your results you can use p<0.05 to say signicant different or p>0.05 to say non-significant differences. Please try to use this. In table 2, you use other two p values, but they were not mentioned in statisticall anaylisis ¿Why?
Figure 5: You have to use "Time (h)" instead of "Time (hr)". The correct acronym for hour is "h". Please increase a little the dots because the reading is difficult.
Figure 6: Please increase the letter´s size for improving the reading.
Table 2: I think this information would be very clearify if you use a figure with regresions. Please try to plot and you have to make a decision to a better reading.
Line 207: " Tha-gen and Thy dom are strongly influenced by wind conditions....". Please check this affirmation because if you look Table 2, in the case of Tha-gen the correlation with wind speed is only 0.02.
Discusion in general: you told about your results and the explanation of why these results, but you didn´t tell anything about results from other authors. In addition you can say many things about the implications of your evapotranspiration values to manage the situation in the national park, but you didn´t mentioned in all. Please check.
Please check if it is correct to calculate Kc value for water. I'm not really sure about that, because the methodology proposed by FAO is applied for crops.
Author Response
Thanks for your review. See the reply in the attached file.
Author Response File: Author Response.pdf
Round 2
Reviewer 1 Report
The work on quantification of the evaporation rates of six wetlands covers is interesting to know the effect from this plant to the water fluxes. The manuscript has improved. However, there are still minor issues to go through. Need a grammar check especially for newly added sections.
1. Line 78-79: other regions? Be specific.
2. The question raised by Q.27 is, if the authors used the 1.27 mmd-1 for all the days.
In the answer to the Q.27, the authors mention that “The water adding to water added to the lysimeter during the daily measurement was considered as dS/dt and the precipitation as P”. Then this should be added to the manuscript. This was not clear in the section between the lines 185-186. Does that mean in eq. 2 ds/dt = P?
3. Lines 203-213 in discussion section are measurement more than the results. Consider shifting to the measurements section.
4. Line 221-223: To make ease for the reader the authors could present the standard deviations together with the average values with ±.
5. Table 1: For what this different lower case letters refer to? Do the authors mean the similar letters indicate that there is no different? Please improve the caption. It is still not clear by the answer to the question 34.
6. Figures in Appendix: Please increase the font size
7. Line 267-269 and line 2734-276: please check the sentence structure and correct grammatically and meaningfully.
8. Line 270, 342, 344 : does, is, shows,- check for the grammar
Author Response
In blue we copied the comments of the reviewer, in black our reply:
1. Line 78-79: other regions? Be specific.
We add the following:
“::: evaporation in other regions (e.g. Suriname, South Africa, United States). :::”
2. The question raised by Q.27 is, if the authors used the 1.27 mmd-1 for all the days.
In the answer to the Q.27, the authors mention that “The water adding to water added to the lysimeter during the daily measurement was considered as dS/dt and the precipitation as P”. Then this should be added to the manuscript. This was not clear in the section between the lines 185-186. Does that mean in eq. 2 ds/dt = P?
Between lines 85 and 86 it is explained each of the components of Equation 2. “P” corresponds to the precipitation on a daily basis and in this experiment only 1 day experiences precipitation. This day is mentioned in the Results section between the lines 212-213 and it was used only for the 27 of December. However, we proposed to improve the description of dS/dt as follows:
“:::, which corresponds to the water added manually every day in the morning (mL) to replenish the evaporated water. The water was added if the precipitation was not enough to fill the lysimeter or if the water level was lower than the overflow drainage outlet in the lysimeter.”
3. Lines 203-213 in discussion section are measurement more than the results. Consider shifting to the measurements section.
These lines are located within the Results section because describe the meteorological conditions during the study period. Additionally, the Discussion section starts after line 259.
4. Line 221-223: To make ease for the reader the authors could present the standard deviations together with the average values with ±.
We improve the text according to the suggestion as follows:
“Tha–gen evaporates 17.0 mm±2.42 d−1 on average, with a slightly decreasing trend towards the end of the period. Contrary to Tha–gen, Typ–dom intensifies the evaporation in January but the average evaporation remains lower than Tha–gen with 14.3±3.39 mm d−1. The Mixed cover evaporates 13.5±2.44 mm d−1 having a similar standard deviation as Tha–gen (Figure 7).”
5. Table 1: For what this different lower case letters refer to? Do the authors mean the similar letters indicate that there is no different? Please improve the caption. It is still not clear by the answer to the question 34.
We improve the caption as follows:
“Average values of crop coefficient, daily and accumulated evaporation rates for the selected wetland covers at Palo Verde National Park, Costa Rica. Each average is based in 40 days of measurements and five replicates. Average values on the same column with similar lower case letters (a,b,c,d) do not show statistical differences (p=0.05) according to the Fisher LSD test.”
6. Figures in Appendix: Please increase the font size
Done and added to the manuscript.
7. Line 267-269 and line 273-276: please check the sentence structure and correct grammatically and meaningfully.
We modified the lines 267-269 as follow:
“The temperature have a strong influence (p<0.001) on the evaporation of the Eic—cra, Open Water, Mixed and Typ—dom covers. Meanwhile, the evaporation rates of Nep–nat and Tha–gen are driven by solar radiation, and the vapor pressure deficit also influences Nep-nat. The emergent macrophyte Typ–dom and the Mixed cover are strongly influenced (p<0.001) by wind speed.”
We modified the lines 273-276 as follow:
“The VPD and relative humidity are the main drivers of the evaporation process during this period for all the covers excepting Tha–gen. The lack of correlation between evaporation and VPD or relative humidity is not unusual and it has been documented with other macrophytes as Typha latifolia, Hacer rubrum and Salix babylonica with correlations between -0.14 and -0.46 in the United States[33].”
8. Line 270, 342, 344 : does, is, shows,- check for the grammar
Reply:
Line 270 changed to: “Despite the differences of foliar area among the wetland covers, the accumulated evaporation in Open Water, Nep–nat and Eic–cra do not differ”.
Line 342 changed to: “::: the evaporation rates are strongly correlated with the :::”.
Line 344 changed to: “These results show that the increment :::”.
We did a grammar check through all the manuscript.
Reviewer 3 Report
The manuscript was improved significatively according to reviewers instruction. However I didn´t agree with one of your answers.
Question: Line 10: ¿Why the monitoring time was very short?.
Answer: The monitoring was established for the beginning of the dry season due to budget restrictions during the data collection.
When you are doing science you have to do a good experimental design according to your budget.
Please provide inside the manuscript one short explanation and/or clarification in scientific way for monitoring only 45 days. (Line 171-172).
In addition, Line 90, 91 y 271, were written in first person. Please change the redaction to infinitive person.
Author Response
In blue we copied the comments of the reviewer, in black our reply:
1.- The manuscript was improved significatively according to reviewer’s instruction. However, I didn´t agree with one of your answers.
Question: Line 10: ¿Why the monitoring time was very short?.
Answer: The monitoring was established for the beginning of the dry season due to budget restrictions during the data collection.
When you are doing science you have to do a good experimental design according to your budget. Please provide inside the manuscript one short explanation and/or clarification in a scientific way for monitoring only 45 days. (Line 171-172).
Reply:
We add the following in Line 170:
“The measurements were carried out during the beginning of the dry season considering the importance of the evaporation flux as the main driver of the wetland hydrology during this season. The water availability and growing stage of the macrophytes during this period allow determining the crop coefficient of the individual wetland covers.”
2.- In addition, Line 90, 91 y 271, were written in first person. Please change the redaction to infinitive person.
Line 90 changed to:
“Additionally, it is important to investigate the difference between individual wetland covers where eddy covariance systems are not suitable.”
Line 91 changed to:
“Therefore the lysimeter technique allows the estimation of evaporation rates of individual covers in a smaller scale [46].”
Line 271 changed to:
“The estimation of the VPD based on the relative humidity measurements provides an indication of the maximum water vapor that can be allocated to the atmosphere.”
