the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
| 21 Oct 2025
QUADICA v2: Extending the large-sample data set for water QUAlity, DIscharge and Catchment Attributes in Germany
Abstract. The QUADICA version 2 dataset significantly expands upon the first version of QUADICA (water QUAlity, DIscharge and Catchment Attributes for large-sample studies in Germany), by incorporating more recent data, additional water quality and driver variables, and more stations with concurrent water quantity data. Specifically, QUADICA v2 extends the time series of the first version up to 2020 and introduces new water quality variables, including water temperature, oxygen, and chlorophyll-a concentrations, as well as concentrations of ammonium, sulfate, and geogenic solutes like calcium. These additions enable a more comprehensive understanding of ecological impacts, including eutrophication effects, and water quality dynamics across catchments. Furthermore, we have integrated QUADICA with the hydrological large-sample datasets CAMELS-DE and Caravan-DE, effectively doubling the number of stations with combined water quality and quantity data to 637 out of the 1386 stations in total. The inclusion of time series on point and diffuse sources of both nitrogen and phosphorus allows for more thorough investigations of driver-response relationships and nutrient export from catchments. To facilitate visualization and exploration of QUADICA, we provide a user-friendly, interactive R application along the online data repository. This makes QUADICA v2 a comprehensive dataset that spans from driver to impact variables, offering a valuable resource for researchers and practitioners.
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Status: open (until 27 Nov 2025)
- RC1: 'Comment on essd-2025-450', Anonymous Referee #1, 27 Oct 2025 reply
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RC2: 'Comment on essd-2025-450', Anonymous Referee #2, 02 Nov 2025
reply
In this data paper, Ebeling et al. present an updated version of their QUADICA database, which provides data on water quality and its controlling factor across Germany. Compared to the original version, QUADICA v2 contains additional water quality parameters, monitoring stations and data on 'driving forces'.
It is a comprehensive and well-described database, and the updates are significant enough to justify a second data paper on QUADICA. The database will be invaluable to scientists working on water quality and its controlling factors.
The only drawback of QUADICA v2 is that it only includes aggregated annual or monthly data, not raw data. This is a pity, as it will prevent its use for some potential statistical analyses. However, the authors explain that they had no choice because data providers have strict policies regarding data sharing.
Citation: https://doi.org/10.5194/essd-2025-450-RC2
Data sets
QUADICA v2 - water quality, discharge and catchment attributes for large-sample studies in Germany, HydroShare P. Ebeling et al. http://www.hydroshare.org/resource/0ec5f43e43c349ff818a8d57699c0fe1
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- 1
Ebeling and colleagues updated the very relevant QUADICA dataset in this extension of the original with both more measurements and data. It is undeniable the relevance of the current contribution, and given some concerns are clarified I see no further obstacle in eventually having the contribution published in ESSD.
1. L31: Is the data updated until 2020 or 2022? I see some parts of the paper where the 2020 is mentioned, and others where there is the 2020. I recommend to be coherent throughout the manuscript with one end_date.
2. L36-37: Impressive and very useful. However as a reader I found it difficult to understand what the authors meant at first. I would please ask the authors to rephrase this part to make it more clear to the reader at first glance their significant contribution.
3. L57: Please consider using the published version here in the reference instead of the preprint (https://doi.org/10.1038/s41597-025-05625-1)
do Nascimento, T.V.M., Höge, M., Schönenberger, U. et al. Swiss data quality: augmenting CAMELS-CH with isotopes, water quality, agricultural and atmospheric data. Scientific Data 12, 1283 (2025). https://doi.org/10.1038/s41597-025-05625-1
4. Please consider adding the recent and also relevant contribution by Zarei and colleagues covering Iranian rivers (in case it makes sense for the authors):
Zarei, E., Noori, R., Jun, C. et al. A Comprehensive Water Chemistry Dataset for Iranian Rivers. Scientific Data 12, 1646 (2025). https://doi.org/10.1038/s41597-025-05932-7
5. L017-111: This is a very long parenthesis. Could you please rephrase to improve the flow in the text?
6. Maybe I am being too pendant about the map, but would not make sense to also add the north and one scale bar in km also? since it is a map in the end.
7. Data records: I really appreciate that the authors already included a descriptive metadata in the dataset. It is great that you point users to the section in the manuscript that each table refers. However, I would appreciate if you could also insert such link in the manuscript. So for ex, in section 3.1.1 you could already point that the data is further described in Table S2? I assume that the metadata works as a Supporting information? Or in case not, I would strongly recommend to have a Supporting information with the same information as in the metadata downloadable with the dataset!
8. L243-244: What do the authors mean here?
9. L328: I could not find the catchment attributes data in the dataset. The metadata points to another repository with last updated data from 2022. Is this the correct path? If yes, is there a reason why you are not publishing all the QUADICA v02 dataset together?
10. Section 3.4: In the metadata you point to N_SURPLUS data, but in the manuscript section I had the impression that you had available both N and P surplus. Is it true? if yes, where is it stored? Again, I think that having a table, like S7 directly mentioned in the manuscript would help the users and readers!
11. 4.2 Why is LAI only from 2003-2018 made available? Is there any reason for not including the years up to 2020?
Given these clarifications are made, I would be willing to further review the paper for next steps.