The reviewer was invited as a third reviewer of this paper, and this will be the first review. The authors present long-term flood/drought variations in the Hanjiang River Basin (HRB) in central Chia from 1426 to 2017 based on historical documents and meteorological and hydrological data in recent years. The results will be valuable for understanding long-term climate change history in that region. Although the target region is not very large, this kind of regional climate change study will be valuable. According to the responses to the former reviews, the authors seemed to make major revisions in this version. However, still remained a number of ambiguous points as listed below, and the paper needs major revisions.
1. They showed Figure 3 to show the validity of their flood/drought index and observed precipitation. They concluded they were well correlated and their flood/drought index was reasonable. However, when the curves are compared with the years in Table 2, the listed extreme flood and drought years seem not to match with the minimum or maximum of the curves in Fig. 3. Will they plot these extreme years in Fig. 3 to check the validity of these data and explain the reason of the differences if they differ in some years?
2. They divided the whole period into three stages. But in the latter description it seems nothing was considered on interpreting the results. It will be needed how they treated such data discrepancies during the target period.
3. Their terminology in describing place/region names is very vague as pointed out below, and sometimes not consistent in the paper which greatly prevents the content from easy understanding.
4. Sometimes, their results seem to contradict with or are different from the former studies results, but they simply regarded these portions to be “consistent with the former studies”. They need to carefully compare their results with the former studies and explain the reason for the discrepancies.
5. Although they seem to add English references, adding two more important former studies on long-term Asian monsoon variability from the 15th century by Shi et al. (2018, 2019) will be recommended.
1. L26-28: It is rather hard to understand the relationship between the lower flood/drought frequencies in the upper reach, and the highest sensitivities to droughts and floods in the Ankang region located in the upper reach.
2. L44-45 and many others: The reviewer is not familiar with this journal’s citation policy, but normally, the cited references are arranged from old to new, or alphabetical order.
3. L65: The word “especially” may not be needed, since this situation is not limited to eastern China’s monsoon region.
4. L112-113: Need to add the averaged periods for the average annual precipitation and runoff.
5. L116-117: It is not sure if these topographic features are the main reason for the severe droughts and floods.
6. L119: In Fig. 1 “Jianghan Basin” is labeled, not “Jianghan Plain”
7. L139: “century AD” -> “century BC” (?), since “for more than 3000 years”.
8. L141: Many people will not be familiar with the period of “Qing Dynasty”. It will be better to specify the target period of this dataset.
9. L157: It seems all these stations are in the HRB. Which stations are “around HRB”?
10. L185-186: It was not clearly understandable the terms “representative area”, “site”, and “most counties’ situation”.
11. L188-191: The method how to make this ideal frequency needs to be explained.
12. L208: This definition of the term “site” needs to be explained earlier (See comment 10). Better to show county and municipalities boundaries in Fig. 1 or explain such region names’ conditions. Also add how they are called in Chinese.
13. L230: Is there any meaning of the value “20%”?
14. L236: How do you calculate the precipitation anomaly percentages? Is it just 8 station mean value? Are the interannual variabilities within only several percent? Then it will be highly stable precipitation regime.
15. L285: In the 1580s and 1730s no extreme droughts are listed in Table 2. Also, no extreme droughts are in 1628-1641. Are they indicate the inconsistent results with this paper?
16. L294: When and where the “Ming Chongzhen drought” occurred?
17. L297: When is the Danjiangkow Reservoir constructed? For which purposes?
18. L298-299: Which region’s average precipitation are these values indicated?
19. L301: 1660s -> 1610s.
20. L306: Are any flow rate data available before 1959? It is not sure if the 20 times are abundant or not from this description only.
21. L311: Need to show the recorded period to indicate the “record high”.
22. L312: Is “lake Taibai” located in Fig. 1? If yes, please label it, or if no, please indicate how much it is located downstream of the eastern limit of Fig. 1.
23. L315: The years 1631-1632 and 1979-1980 are not listed in Table 2.
24. L323: Where is Wudu County located, and same comment as No. 22. Same as for the Baiheliang stone fish in L326.
25. L353-355, Table 3: According to the definition of extreme flood/drought years in L250-255, they are not the same as Grade 1 or 5 years. It is very confusing that they used extreme flood/drought years to be similar as Grade 1 or 5 years.
26. L 367-368: From Figure 5, both floods and droughts are higher in the lowland not in the upper reaches. Isn’t it a different result from the former studies?
27. L369-373: In L118, Zhongxiang is regarded as a starting point of the downstream, but here it is regarded as the middle reach which make the readers to be confused. In addition, Qianjiang and Wuhan in the lowland have higher drought frequency than in the upper catchment. Need more careful description.
28. L373: From the figure 5 -> From Figure 5
29. L382: It is not clearly understandable why they regarded higher flood/drought grades in Fig. 6 to be “sensitive”.
30. L402-404: Why upper HRB droughts are more correlated with droughts in North China, while middle and lower HRB floods have stronger relationship with the middle and lower Yangtze River Basin? Any climatological evidence in recent years?
31. L461-468: The comparisons with East and South Asianδ18O show not strong relationship with flood/drought frequencies in the HRB. Need to change their discussion on this point.
32. L501: Any explanation on the reason why the HRB is more prone to floods when the South Asian monsoon is stronger?
33. References: He does not know this journal’s policy but the reference order may need to be arranged alphabetical order. In addition, use consistent style for small/capital letter usages in the titles of the paper and/or the journal names.
34. Fig. 1: As for (b), it is hard to distinguish green filled circles indicating study site from the background pale green color in the lowland areas. Better to change the color of the study area to be more easily distinguishable color. Put label of “Qinling Mountains” to be located somewhat southward, since they will be the northern boundary of the HRB. In addition, add unit for the color bar.
35. Fig. 4: The method of making this figure is questionable. 1. In the graph, the earliest year is labeled as 1426, but the caption shows it is from 1430. 2. It is not very sure how the precise year is located. For example, in Table 2, 1433 is listed as one extreme drought year in the 1430s. Maybe it is plotted as the second decade one extreme drought in Fig. 4a. No extreme flood year is listed during the 1420s or 1430s in Table 2. However, in the first decade starting from 1426, one extreme drought and flood is listed in Fig. 4c. The situation in the 1990s are also not clear. How do you define 10-year period? Is it starting from the year xxx0 oy xxx1? 3. Why you did not include the 21st century record? If you use the whole period data, it should be from 1426 to 2017, shouldn’t it?
36. Fig. 5: The color bar for drought condition map will be better to be changed to indicate reddish color to be higher frequency, like their drought grade maps, since bluish color may feel wetter conditions.
37. Fig. 9: The top right figure label will be “drought years”, not “flood years”.
38. Table 2: The top line of the 20th Century Extreme drought years: 194 -> 1941
Shi, H., B. Wang, E. R. Cook, J. Liu, and F. Liu 2018. Asian summer precipitation over the past 544 years reconstructed by merging tree rings and historical documentary records. J. Climate, 31, 7845−7861, doi:10.1175/JCLI-D-18-0003.1
Shi, H., B. Wang, J. Liu, and F. Liu 2019. Decadal-multidecadal variations of Asian summer rainfall from the Little Ice Age to the present. J. Climate, 32, 7663−7674, doi:10.1175/ JCLI-D-18-0743.1