Tijdeman et al. (2021); NHESSD

Tijdeman et al. (2021) compared hydrometeorological drought hazard and associated propagation characteristics with impacts of major droughts between 1990-2019 in Southwestern Germany. This manuscript is written clearly, and it is an interesting study, particularly by linking different drought types and impact characteristics. Although only a regional (sub-national domain) is explored, this limited spatial extent is balanced by a larger number of variables explored. Among other results, the strongest agreement between impact start and drought hazard was found for soil moisture and river flows, while precipitation and groundwater showed a weaker relationship. I provide a number of minor recommendations, which I would like the authors to address before recommending for publication. 

(1) It is not clearly defined in the manuscript, whether the P & T & SM variables are averaged over individual catchments or average over the entire BW region is performed (e.g., in Figure 2). There is a large spatial variation in meteorological variables due to the Alps, so this needs clear clarification. 

(2) What is the soil moisture representation from the TRAIN model? Please, provide some more details about the representativeness of this model with respect to soil moisture observations.  

(3) The title of section 2.4 requires a more intuitive name.

(4) Line 224: how do you distinguish between quick and slow developing drought? I have missed this definition.

(5) Line 232-235: More clarification for these conditions is required, the current explanation is too brief. 

(6) Section 2.6, provide a formulation of A in mathematic form. Additionally, in analogy to line 248, explain the meaning of A=1.

(7) Figure 2: Why P12 and T12 do not have not the same scale. P12 is monthly, T12 is annual. Would not it make more sense to have it the same?  

(8) Ticks on the x-axis of fig.2: ticks should be displayed for 1.1.YYYY, rather than the current version. 

(9) Please, explain, what happened during the year 2005? There were also several months of exceptional drought conditions identified but never discussed. 

(10)   Regarding the impacts, considering just the number of reported impacts is a big simplification. Can you quantify them as well using more quantitatively (e.g., financial losses, crop-yield losses?)

(11) Where is the statement on lines 423-424 supported by earlier presented results? 

(12) Two sentences on lines 426-427 require reformulation. 

(13) Discussion can be possibly extended with the following suitable references: https://doi.org/10.1088/1748-9326/aba4ca on impact assessment with text mining; https://doi.org/10.1088/1748-9326/abe828 on assessing multi-year droughts by different aggregation periods.

(14) The current data availability statement is not sufficient. Please, provide your processed data presented in this manuscript on the online repository. 

 

Further textual suggestions:

Line 10: “the environment …” 

line 11: in => into 

line 340: word missing in the sentence. 

General Comments

This article explores characteristics of recent droughts in southwest Germany, contrasting several physical indicators of drought as well as records of drought impacts. It finds that as the scale zooms in to the most local level, causes and effects become more complex.

On the whole, I find this to be a strong paper, well-done, with interesting and informative figures. My comments are intended to help make it clearer. The rigorous analysis of how impacts do and don’t align with physical indicators of drought at different spatial scales is particularly valuable and may be this paper’s most unique contribution.

Specific Comments

One of the conclusions is that “multivariate” drought management is needed, in recognition of the complexity of the relationship between drought and drought impacts, especially at the local level. It may be more appropriate to talk about multi-sectoral drought management, recognizing that, for example, water suppliers, farmers and ecologists generally measure and manage drought and drought impacts within separate scopes of decision-making. A reference to whether or not cross-sectoral drought planning occurs and is coordinated by any central authority, or whether that question requires further investigation, would be helpful.

It would be easier to read if the authors refrained from using variable abbreviations throughout the discussion, such as “Ipv” instead of “initiation time”, “Q” for “catchment,” etc. The statements on lines 230-231 and 234-235 would be easier to read if they were converted to sentences, because their current form requires readers to remember several different abbreviations.

Investigating the phenomena of “ordering, time-lag and lengthening” of drought at different spatial scales is central to this analysis. It would be helpful to provide more explanation and cite references. What does the conventional wisdom (the literature on ordering, time-lag and lengthening) say? Is that what is being tested in the hypotheses? Why or why not?

Technical Corrections

Editing for English syntax would be helpful, to streamline sentences such as the one on lines 84-86.

The authors use the abbreviation “for resp.” several times and I am not sure what it means.

Line 121: Missing a word before “own”?

Line 340: missing word after “from”