This study investigated the impacts of prolonged meteorological drought and asymptotic climate variation on catchment hydrology. The authors found that climate change has significant impacts on water storage capacity. Generally, I found this study is relatively novel, and fits well to the scope of HESS. And the results could benefit the community to further understand how terrestrial ecosystem responses to climate change, and their impacts on water resources. It has potential to be published in HESS. But I found some very important issues and biases, which need to be addressed before considering for acceptance.

1. The catchment water storage capacity (CWSC) concept is not rigorous, and probably misleading. The CWSC is huge and unclear in most cases, which at least includes the water storage capacities of soil, groundwater, and surface water bodies, including rivers, lakes, and artificial reservoirs etc. In this study, the authors used the GR4J model, which has four parameters, θ1, θ2, θ3, θ The authors said “θ1 is the capacity of runoff producing reservoir in the catchment (mm)” and “θ3 is the capacity of catchment reservoir (mm)”. I am confused with these statements, and the physical connection between CWSC and the θ1 and θ3 parameters. To my understanding, the authors may want to say the active catchment water storage capacity, i.e. the root zone storage capacity, which determines rainfall-runoff process, by splitting rainfall into infiltration and runoff. For more research and discussion on this issue, the authors can refer these papers: https://agupubs.onlinelibrary.wiley.com/doi/full/10.1002/2014GL061668; https://hess.copernicus.org/articles/20/1459/2016/; https://hess.copernicus.org/articles/20/3361/2016/. In Line 509-513, the authors also mentioned that “the increased forest coverage of the catchment resulted in the larger water demand of the ecosystem, and thus a shorter response time of the CWSC to the meteorological drought.” From this statement, I feel the authors also agree with me that the CWSC is a parameter related to ecosystem, rather than the total catchment water storage capacity. Also, they said “catchment has experienced a prolonged meteorological drought, it would respond fast due to its large water demand”. Obviously, ecosystems have water demand, rather than soil or groundwater. Hence, both thought experiment and overwhelming evidences manifest that the root zone storage capacity of ecosystems determined the separation of rainfall to runoff and infiltration, rather than the total CWSC. Moreover, from the perspective of ecosystem response to climate change, the paper becomes more interesting, not only for hydrologists but also for ecologists etc.
2. The literature review is not comprehensive. There are already many important publications to understand both climate change and landuse change on time-variation of the root zone storage capacity. Please find more details here: https://hess.copernicus.org/articles/20/4775/2016/; https://hess.copernicus.org/preprints/hess-2021-204/.
3. The English writing is readable, but still has room to be improved. The improvement on writing might not take much time for the authors, but can significantly improve the presentation quality and increase its impact.

Hope these comments can be helpful to improve the quality of this manuscript.

In this manuscript, the authors try to identify the temporal changes in the water storage capacity of the catchments in Australia due to prolonged meteorological droughts and highlight the factors responsible for causing such changes. 

Based on my initial assessment of just the title, abstract and the research questions proposed in the Introduction, I found this research quite relevant for the larger hydrological and ecohydrological community exploring ecosystem response to droughts, changes to above- and below-ground water resources and predicting such changes under future climate change. However, after reading the manuscript, I had several major concerns.

Major comments:

• I was confused by the term ‘catchment water storage capacity’. However, after reading the manuscript, I thought the concept explored in this study was similar to ‘root zone storage capacity’. It would make sense to use terms already well established and accepted in the scientific community rather than introducing new terms. Authors should cite appropriate literature in the manuscript related to earlier and recent work about root zone storage capacity exploring their response under changing hydroclimate. 
• The authors have used the word ‘asymptotic’ (i.e., the influence of droughts/climate change on catchment’s water storage capacity seasonally) quite frequently (every 3-4 lines in the Introduction) as a central research gap that is addressed in this manuscript. However, after reading the whole manuscript, I am still unsure how it was addressed. This is because authors haven’t clarifyied how the trends observed in catchments due to prolonged meteorological droughts have permeated to show changes in seasonal hydrological trends of the catchments. 
• The authors had used the change in root zone storage capacity (i.e., catchment water storage capacity) before and after the prolonged droughts and correlated it with catchment and climate characteristics to infer relevant factors influencing the catchments. But does a high correlation mean causation as well? The authors have neither provided a concrete justification about probable catchment dynamics in response to the droughts nor cited a single literature in the ‘Results and discussion’, which makes it difficult to understand their reasoning. Furthermore, the characteristics of soil and forest cover are rarely discussed. Although these factors play a major role in influencing/partitioning storage and runoff of the catchments.
• The manuscript's language needs to be improved considerably for it to be considered for acceptance in HESS. My main concerns are related to improper paragraph structure, grammatical inconsistencies (e.g., use of was, is and has been in the first paragraph of Introduction) and repetitions throughout the manuscript (e.g., Line 292-296 already mentioned in Methods). Although I have not included all inconsistencies that I found in the manuscript in this comment, the authors should check for them carefully.

Specific comments:

• The catchment's response to prolonged droughts would have already covered any seasonal response. Do authors think that using the word ‘‘asymptotic’ adds any value to the analysis presented?
• Line 55-62: Authors briefly discuss the strengths and weaknesses of statistical techniques but don’t discuss the limitation of hydrological models. Is there none in the context of modeling, parameterization, etc.)?
• Line 69-73: Is climate change not considered under changing environment? Are the authors claiming the hydrological models do not consider climate variability on catchments? Please provide appropriate citations to this statement.
• Authors have referred to a publication ‘Pan et al. (2020)’ as ‘our previous study’, and highlighted this study as the extension of the study mentioned above, addressing previous studies' time-based research gaps. I would recommend authors to dedicate one paragraph to ‘Pan et al. (2020) to briefly discuss the necessary context, rather than discussing it in bits and pieces (Line 77-82, 103-105, etc.)
• Study area and Section 4.1 can be combined as ‘Study area and catchment demographic’ as it adds no novelty to the research gaps.
• Line 129-130: ‘….which had a significant impact on the stability of local ecosystems, and the development of society, economy and politics.’ Add references which highlight this.
• Remove 116-119. Since the sections and subsections are already there, this paragraph is unnecessary.
• Check the equation in section 3.2.2 Criteria (2).
• Line 253: NSE is abbreviated before it is defined. Authors can probably keep the un-abbreviated words for sub-headings.
• Line 261: I still do not understand Criteria (3): Robustness requirements of the results. Clarify.
• Line 321: Avoid starting a sentence with a number.
• Is the word ‘significant’ used to refer to statistical significance, i.e., p < 0.05? If so, make this clear in the manuscript and caption of the figures.
• Line 334-337: Cite the appropriate table. The authors have also not adequately cited tables and figures in appropriate places. Check.
• Line 407-408: ‘……while those of catchments with significantly downward changes in 𝛼 are 391.9 and 422 days, respectively.’ What does ‘upward/downward change’ mean? And why is the response time less than the upward change?
• ‘Results and discussion’ section needs to be structured properly. For example: Line 461-463: ‘Since no strong correlation between the amplitude and a single factor is found, therefore we speculate that the potential change of the variation range of the CWSC is the result of the combination of various catchment features and climate factors.’ Discuss what those feedbacks could have been. So far the ‘Results and discussion’ sections seem like just ‘Results’ without any citation justifying the claims made by the authors.
• Line 439-445: ‘On the whole, we can get the conclusion that: catchments with small area\ low elevation\ small slope range\ large forest coverage and AWHC soil may change more significantly than catchments with opposite characteristics. It is likely that the resilience of catchments with small area\ low elevation\ small slope range\ large forest coverage and high AWHC soil is poor, and which result in an easy change in CWSC of these catchments after the interference of meteorological drought.’ Why would the resilience of a catchment with a low elevetion and high forest cover be poor? What is the reasoning here? Cite appropriately as well.
• Line 487-493: ‘In general, soil and forest percentage are the most related variables to the mean value. The water holding capacity of various soil types is different as the dissimilarity of void and adhesion in different soil types, which directly affects the ability of the catchment to absorb and store water, and then affects the CWSC of the catchment. Furthermore, the coverage of multiple forest percentage would affect the water holding capacity and water assumption ability, resulting the potential changes in the CWSC.’ I would have preferred more soil and forest cover discussion on the catchment’s water storage capacity.
• I had concerns about some of the words that are used in the manuscript:: ‘....different climate-changing patterns’ (Line 34),  ‘stronger robustness’ (Line 170), ‘lumped conceptual’ (Line 178), ‘differentiated soil composition’ (Line 273), ‘remarkable increasing trend’ (Line 404), ‘remarkable convergence patterns’ (Line 355), and many more.