Deconstruction of Dryness and Wetness Patterns with Drought Condition Assessment over the Mun River Basin, Thailand

Round 1

Reviewer 1 Report (New Reviewer)

In this study, dryness and wetness pattern, the drought intensity, frequency, and duration are investigated in the Mun River basin, a typical region that frequently suffers a drought. Standardized precipitation evapotranspiration index (SPEI), Ensemble Empirical Mode Decomposition (EEMD), correlation analysis, and Pettitt test are carried out to identify the drought intensity of the region. This is an interesting paper written by confirmed authors who have published several papers in very important journals on the same or similar drought study. It was of great help to the development and later research of the drought study. The main findings are interesting, and the supporting materials and perspectives are adequate. Although this type of study is essential and would be of interest, it falls short of success in several areas. It needs moderate further revision.

 

Specific comments:

1. Lines 148: alphabet or number in equations should be in italics.

2. In Lines 153;158, the authors do not start any sentence with an abbreviation or a number.

3. Lines 157 and 177, please keep consistent, or complete spelling with an abbreviation, or complete spelling without an abbreviation.

4. Lines 305: You used "Fig." in somewhere and used "Figure" in other places. Please Unity before and after.

5. Lines 71: Can you provide a reference to show the drought's significant role in safeguarding agricultural production and safety?

6. Figure 9. The longitude and latitude may be hard to read by some readers, and please magnify them.

7. Line 425, no issue number and volume number for reference.

8. Line 486. The published Journal in the reference should be in italics. Same thing in line 505.

9. In Figures 2 and 8, you used lowercase "a,b,c,d", but the capital letter in other Figures, please revise.

10. In Figure 5, please magnify the legend as you did in Figure 3.

 

Author Response

In this study, dryness and wetness pattern, the drought intensity, frequency, and duration are investigated in the Mun River basin, a typical region that frequently suffers a drought. Standardized precipitation evapotranspiration index (SPEI), Ensemble Empirical Mode Decomposition (EEMD), correlation analysis, and Pettitt test are carried out to identify the drought intensity of the region. This is an interesting paper written by confirmed authors who have published several papers in very important journals on the same or similar drought study. It was of great help to the development and later research of the drought study. The main findings are interesting, and the supporting materials and perspectives are adequate. Although this type of study is essential and would be of interest, it falls short of success in several areas. It needs moderate further revision. Response: Thanks to the reviewer, we have done all the corrections based on the reviewer’s suggestions. See the revised manuscripts. Specific comments: 1. Lines 148: alphabet or number in equations should be in italics. Response: Agreed. We corrected all the equations (Line148,150,151,152,154), same issue raised by the reviewer 2. 2. In Lines 153;158, the authors do not start any sentence with an abbreviation or a number. Response: Sorry, revised as suggested (Line153, line 158). 3. Lines 157 and 177, please keep consistent, or complete spelling with an abbreviation, or complete spelling without an abbreviation. Response: Yes, revised as suggested (Line 157). 4. Lines 305: You used "Fig." in somewhere and used "Figure" in other places. Please Unity before and after. Response: We check the manuscript and consistently used "Figure." in the context. 5. Lines 71: Can you provide a reference to show the drought's significant role in safeguarding agricultural production and safety? Response: We have added some recent published papers (Line 492-495 ). Kuwayama, Y., Thompson, A., Bernknopf, R., Zaitchik, B., & Vail, P. Estimating the impact of drought on agriculture using the US Drought Monitor. American Journal of Agricultural Economics, 2019, 101(1): 193-210. Dar J, Dar A Q. Spatio-temporal variability of meteorological drought over India with footprints on agricultural production. Environmental Science and Pollution Research, 2021, 28: 55796-55809. 6. Figure 9. The longitude and latitude may be hard to read by some readers, and please magnify them. Response: Sorry, revised Figure 9 as suggested, same issue raised by the reviewer 2. 7. Line 425, no issue number and volume number for reference. Response: revised as suggested (Line 437). 8. Line 486. The published Journal in the reference should be in italics. Same thing in line 505. Response: We checked the references, and revised the published Journal to italics (Line 497, line 504). 9. In Figures 2 and 8, you used lowercase "a,b,c,d", but the capital letter in other Figures, please revise. Response: Sorry, revised Figure 2 and 8 as suggested. 10. In Figure 5, please magnify the legend as you did in Figure 3. Response: Sorry, Figure 5 was revised as suggested.

Reviewer 2 Report (New Reviewer)

1.       Line 207-216: You compare the resulting modes IMF to solar cycles and ENSO. Yes, the periods are similar, but how do the phases of these cycles correspond to the observed fluctuations in SPEI?

2.       Figure 5 (A):  how was the intensity of droughts determined? If according to the grades in Table 1, then what are the values plotted on the Y scale in Fig. 5(A)?

3.       Line 285-294, fig. 7: How was the duration of droughts determined, what time scale for the SPEI was used?

4.       In table 3, all values are marked with **, why mention * at the bottom of the table?

5.       Section 4.3: obtained results are interesting from the point of view of changes in the temperature and precipitation regime in the study region. However, are there any suggestions about the reasons for these changes? To advice users of drought information, as you say in the conclusion, should be based on reliable information about the distribution of one or another dry or wet pattern in the region in the current period or in the future. Obviously, this is due to atmospheric circulation, so it is advisable to review scientific studies and provide references that would confirm your conclusions regarding changes in the components of the water cycle in the Mun River basin.

6.       The presence of a monsoon climate in the study region raises the question about correctness of the SPEI index analysis on the time scales of 3 and 12 months in general. What months did you take these indices for analysis, and did it happen that the periods for which the index is calculated included both wet and dry seasons? It would be methodically correct to separate two seasons, choose a time scale and analysed the index separately for each of them, taking into account the duration of each season.

7.       Evapotranspiration is usually denoted simply ET, the scale at the index SPEI-12, SPEI-3, without M.

8.       Formulas 1-5 must be typed using the Formula Editor for correct display.

Author Response

1. Line 207-216: You compare the resulting modes IMF to solar cycles and ENSO. Yes, the periods are similar, but how do the phases of these cycles correspond to the observed fluctuations in SPEI? Response:Thank you for pointing this out. In our study, the SPEI series was decomposed by EEMD into IMFs. The variation of each IMF could represent some characteristic and tendency of the original series of SPEI. The frequency and amplitude of IMF1 and IMF2 were similar to that of the original series of SPEI and the trend of IMF4 corresponded with that of the SPEI. On the inter-decadal scale, the cycle of SPEI was consist with that of IMF3(11.1 years cycle), which similarly corresponded to the cycle of the cycles of sunspots. In addition, ENSO would influence the temperature and precipitation which directly related to the dryness/wetness condition. The variation of sunspots is closely associated with climate change. This was why we compared the cycles of ENSO and sunspots with that of SPEI. 2.Figure 5 (A): how was the intensity of droughts determined? If according to the grades in Table 1, then what are the values plotted on the Y scale in Fig. 5(A)? Response: Drought intensity was determined in the section 3.2.2 line 174-175. “The number of months during in which the SPEI < -0.5 was regarded as the drought frequency, and the corresponding mean SPEI absolute value was the intensity”. In Figure 5A, the values of the Y scale corresponded to the absolute value of SPEI in the second column in the Table 1. 3.Line 285-294, fig. 7: How was the duration of droughts determined, what time scale for the SPEI was used? Response: Drought duration was the number of months between drought starting and ending. Drought duration was investigated based on the 3-month SPEI. (Line 175-176). 4. In table 3, all values are marked with **, why mention * at the bottom of the table? Response: Thanks to the reviewer. The * at the bottom of table 3 was deleted (Line389). 5. Section 4.3: obtained results are interesting from the point of view of changes in the temperature and precipitation regime in the study region. However, are there any suggestions about the reasons for these changes? To advice users of drought information, as you say in the conclusion, should be based on reliable information about the distribution of one or another dry or wet pattern in the region in the current period or in the future. Obviously, this is due to atmospheric circulation, so it is advisable to review scientific studies and provide references that would confirm your conclusions regarding changes in the components of the water cycle in the Mun River basin. Response: We appreciated the reviewer for her or his suggestions to improve the manuscript. We added some important references to support our results about the changes in the temperature and precipitation (Line 309, 334-338, 343-347). For the reasons, on one hand, the decreasing precipitation during the period of 1971 to 1993 was related to the more occurrence of ENSO and fewer La Nina events. In addition, the weakening trend of westward-propagating tropical cyclones from the 1970s to late of 1990s accounted for the significant decreasing rainfall (Line 334-338). As for the spatial variation of the precipitation, it had a close relationship with the summer monsoon circulation and its own location characteristic (Line 343-350). Limjirakan S, Limsakul A. Spatio-temporal changes in total annual rainfall and the annual number of rainy days. 2007, 29:1-21 Limsakul A, Singhruck P. Long-term trends and variability of total and extreme precipitation in Thailand. Atmospheric Research, 2016, 169: 301-317. Mantua, N. J., Hare, S. R., Zhang, Y., Wallace, J. M., & Francis, R. C. A Pacific interdecadal climate oscillation with impacts on salmon production. Bulletin of the american Meteorological Society, 1997,78(6), 1069-1080. Takahashi H G, Yasunari T. Decreasing trend in rainfall over Indochina during the late summer monsoon: Impact of tropical cyclones. Journal of the Meteorological Society of Japan. Ser. II, 2008, 86(3): 429-438. Zhao, Z., Liu, G., Liu, Q., Huang, C., Li, H., & Wu, C. Distribution characteristics and seasonal variation of soil nutrients in the Mun River Basin, Thailand. International Journal of Environmental Research and Public Health, 2018, 15(9), 1818. Tangang, F., Santisirisomboon, J., Juneng, L., Salimun, E., Chung, J., Supari, S., ... & Yang, H. Projected future changes in mean precipitation over Thailand based on multi‐model regional climate simulations of CORDEX Southeast Asia. International Journal of Climatology, 2019,39(14), 5413-5436. 6.The presence of a monsoon climate in the study region raises the question about correctness of the SPEI index analysis on the time scales of 3 and 12 months in general. What months did you take these indices for analysis, and did it happen that the periods for which the index is calculated included both wet and dry seasons? It would be methodically correct to separate two seasons, choose a time scale and analysed the index separately for each of them, taking into account the duration of each season. Response: We agreed. From March to May, it was the summer with the highest temperature over Mun river basin, Thailand. It is the rainy season from June to October under the influence of the southwest monsoon. The cool season is from November to February. In consideration of the characteristic of the climate of Mun River basin, the 3-month SPEI and 12-month SPEI were both used in our study (Line 169-171). The 3-month SPEI of May and the 3-month SPEI of August, September and October could reflect the dryness and wetness conditions in the summer season and rainy season, respectively. The 3-month SPEI of January and February could represent the dryness and wetness conditions in the cool season. As a result, the wet and dry seasons were both taken into account. As for the 12-month SPEI, it could present annual scale droughts characteristics. 7.Evapotranspiration is usually denoted simply ET, the scale at the index SPEI-12, SPEI-3, without M. Response: In the manuscript, we used the variable of the potential evapotranspiration, so the abbreviation of ETr was applied. As for the SPEI_12M and SPEI_3M, we emphasized the difference between monthly precipitation and ETr. 8.Formulas 1-5 must be typed using the Formula Editor for correct display. Response: Agreed. We corrected all the equations (Line148,150,151,152,154).

Author Response File: Author Response.doc

This manuscript is a resubmission of an earlier submission. The following is a list of the peer review reports and author responses from that submission.

Round 1

Reviewer 1 Report

This is the revised version of “Deconstruction of Dryness and Wetness Pattern with Drought Condition Assessment over Mun River Basin, Thailand” by Li et al.

I read through the response letter and the revised manuscript. I am afraid I can only repeat my comments from the previous round of revisions:

It is very hard to understand and follow the manuscript. There are several incorrect sentences, unclear formulations, typos, grammatical errors, etc. The study would largely benefit from major English language editing.

The abstract should be condensed, and it should contain: what is the aim of the study, what were the methods, what are the main findings and conclusions – in this order, and not mixing the parts.

The Introduction should introduce the topic of this paper, only those references should be added which are relevant for the topic of this paper. At the end of the section very clear science questions should be identified. What is the goal of the study? A goal, which should be novel.

Methods section: The methods should be described in a way, so that the results are reproducible – currently this is not the case.

Results section: based on the current description of the methods it is not possible to understand how the figures and results were obtained. It is also hard to understand what each figure shows.

Merged Results and Discussion section lacks references and proper discussion of the results: how do the findings of this study fit into existing literature?

Please find attached an annotated pdf with detailed comments.

Comments for author File: Comments.pdf

Reviewer 2 Report

The manuscript is about a local case study without relevant scientific originality.However, it is well-detailed, explained, and with significant figures.I appreciate this. I think it can be suitable for publication after revision.

The following are my comments on its improvement:

Lines 21 and 23: the differences between SPEI_3 and SPEI_12 are given for granted without explanation. In line 176, SPEI-3M and SPEI-12M are used. Please use homogeneous acronyms.
Line 28: the meaning of the acronym ENSO is not specified in the abstract but only in line 214.
FIGURE 1: I think that the red points indicate rainfall gauge stations (not duration).
TABLE 1: I don’t understand why the sum of the probability in the last column is not one.
FIGURE 6: it’s not clear the meaning of the blues numbers.
FIGURE 7: specify the unit of measure.
FIGURE 8: specify the unit of measure.
FIGURE 9 is missing.
Table 3 is not mentioned in the text.