Assessment of Variability and Attribution of Drought Based on GRACE in China from Three Perspectives: Water Storage Component, Climate Change, Water Balance

Round 1

Reviewer 1 Report

Review comment

Water resource shortage has become an important problem to the global sustainable development, both in short-term and long-term. This manuscript analyzed in spatial and temporal heterogeneity of drought in China according to the basin scale and using the data of terrestrial water storage anomaly (TWSA) from GRACE, and determined their factors. On the whole, the results were reliable and consistent with actual situation, and has good reference value for regional water resources management. Its theme is consistent with the journal. Thus, I suggest published after major revision. Specific advice is as follows:

1, The manuscript had good review on the relevant research, and I found some articles were relatively similar (such as 11. Liu, X.; Feng, X.; Ciais, P.; Fu, B.; Hu, B.; Sun, Z. GRACE satellite-based drought index indicating increased impact of drought over major basins in China during 2002-2017. Agricultural and Forest Meteorology 2020, 291, doi:10.1016/j.agrformet.2020.108057.), so I suggest that it needs to further emphasize the differences with previous research and innovation of this manuscript.

2, A number of impact factors of drought were selected, based on water balance and literature, etc., including climate, human activity and atmospheric circulation indicators. Meanwhile the effect of each factor on the drought in each basin was found using the conventional method, but their drive mechanism needs further discussion. In addition, although the runoff is a key factor in water balance equation, but how does it affect the drought?

3, There were express problems in some sentences, which resulted in the incomplete sentences.

1) Deng, Liu and Mo [16] examined that increased (decreased) precipitation the main cause of wetter (direr) drought conditions, which can explain 20%-100% of changes in WSDI.

2) A comprehensive assessment of dominant factors of drought were in China's major basins, the main objectives of this study are: (1) identify drought characteristic and trends by Drought Severity Index (DSI),---

4, Is China in the east of the Pacific Ocean? (China (73°33′E – 135°05′E，3°51′N - 53°33′N) is in the eastern part of the Asian and European continent, east of the Pacific Ocean. The spatial distribution of annual precipitation decreases from southeast to northwest, and the average annual temperature decreases from south to north, with obvious seasonal changes.)

5, Please make sure the number of the elevation in the figure 1.

6, I think that it don't emphasize method when describing the results in the result section.

Minor editing of English language required.

Author Response

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Author Response File: Author Response.docx

Reviewer 2 Report

Dear authors,

The manuscript should be correted. Please find all comments in attached file.

Comments for author File: Comments.pdf

Please read the manuscript correctly and correct the sentences. 

Author Response

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Author Response File: Author Response.docx

Reviewer 3 Report

This article is an interesting article that is completely in line with the scope of the journal. The first question that comes up is why didn't you use the GRACE-FO data to update your study? I have read the article carefully and if the following points are resolved, I think it is possible for your article to be published.

1.       Title: The "comprehensive" in the title is a bit awkward for me. You can use words that have a more scientific meaning.

2.       Abstract:  The abstract of the article was suitable in terms of content. LULC and Land Use and Land Cover are the same terms. You can delete one of them in your abstract (line 21).

3.       Keywords: Be more careful in choosing your keywords.

4.       Introduction: In one of the official pages of the Grace satellite (https://nasagrace.unl.edu/About.aspx), three indicators are used to evaluate the drought and its information is prepared for downloading. The resulting fields of soil moisture and groundwater storage variations are then used to generate drought indicators based on the cumulative distribution function of wetness conditions during 1948-2014 simulated by the Catchment model. Houborg et al. (2012) provide complete details on U.S. GRACE-based drought indicator product generation. To improve the value of your work, be sure to include information about them in your introduction.  I also saw articles that I do not think need to be included in the introduction. The following articles that have been published recently can be included in the introduction.

·         The Spread of Multiple Droughts in Different Seasons and Its Dynamic Changes, https://doi.org/10.3390/rs15153848.

·         Drought Prediction: A Comprehensive Review of Different Drought Prediction Models and Adopted Technologies, https://doi.org/10.3390/su151511684

·         Heuristic data-inspired scheme to characterize meteorological and groundwater droughts in a semi-arid karstic region under a warming climate, https://doi.org/10.1016/j.ejrh.2023.101481

5.       Materials and Methods: This part was fine.

6.       Results: The results part was good, but the number of Figs was too many. Try to move the additional figures to the appendix in the revised version.

7.       Other parts (Discussion and Conclusion) were fine.

 

 

Author Response

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Round 2

Reviewer 1 Report

The Conclusion section should not describe too many results, please refine the expression.

Author Response

Thank you very much for your comments and suggestions about our manuscript, which help us to improve the manuscript, substantially. Your suggested revision and comment were accurately incorporated and considered. We have revised the Conclusion section of the manuscript according to your valuable suggestions. The changes in the revised manuscript are highlighted in yellow. Details can be obtained from the revised manuscript.

The Conclusion section was revised as follows:

5. Conclusion

Climate change and human activities are the two main factors influencing changes in TWS [67]. In this study, variability and attribution of drought derived from TWS deficits were analyzed from 2002-2017 for China. The main results are as follows:

1. Based on run theory, almost all humid and arid basins experienced major drought period of 2002-2006 and 2014-2017 respectively. Southern IRB and central YZRB arose a clear center of upward trend and others show a downward trend.
2. Groundwater abnormal decreases is the main cause of drought triggered by TWS deficits in most basins.
3. ENSO is the strongest teleconnection factors in most humid basins, and NAO, PDO, AO are the strongest teleconnection factors in arid basins and PRB. Most of the significant resonance cycles are 12-64 months signals in the period of 2005-2014.
4. The impact of human activities, LULC has become equally or even more significant than natural factors like runoff and teleconnection factors in influencing hydrological drought in most basins of China.

This study confirms the dominant factors from comprehensive perspective on hydrological drought in China’s major river basins, which is of great significance for optimizing the allocation of regional water resources and inspiring development for agriculture and urbanization in China.