The manuscript presents the ISTD, a database of sediment transport measured along Italian rivers. The text reads clearly, and the presented material is very interesting and useful in many applications.

A few comments that I hope will be useful in further developing an already good manuscript:

- lines 94-101: here you address limitations in terms of data connected to total sediment transport. It would be good to see a more extended discussion on the influence of natural and human-driven pressures on suspended and bedload, and on the need for proper, but separated, datasets to actually understand different processes. This might help in further connecting this paragraph to the following one on collecting suspended sediments data in Italy

- l.107-108: can you name these virtuous cases?

- l.143-147: standards on sediment transport data are very much limited, but the sentence “This participatory process enabled the identification of the most effective approaches to standardize data formats and ensure consistency and interoperability across heterogeneous datasets.” sounds a bit too risky, as questions might arise on how “most effective” was evaluated. Did you consider other approaches? What was the rationale behind the process of standardisation? Do you think that different stakeholders might have led to different standards? More details on this would help, especially if other scholars would like to replicate the approach in other regions

- sec. 2.1: in describing the database, it would help knowing a bit more about sustainability (where is the server hosted and how its long-term functioning will be guaranteed, to avoid problems that happened in the past?) and quality control (how are the different roles established? do you have guidelines?). The quality check procedure might be even more important in the case of newly measured data

- before describing the results, it might be good to provide a map of Italy with both rivers and river basins reported in the database. Even if accessible online, such a map could help readers see how monitored rivers are distributed across the country. This might supplement the detail given at lines 386-389

- l.298-303: I fully agree on the need for metadata to obtain reliable and interpretable results, and this loss of details questions the reliability of the data associated with “unknown”. It would help to have some comments on the quality of those data, and their limits of applicability. Authors are encouraged to provide more critical feedback on the database

- is Figure 7 (and the related analysis) influenced by the temporal coverage of the data, for example with old data monitored less frequently?

- l. 372: I would not call it “temporal complementarity” as I see this term too positive, while, in my opinion, the lack of contemporary measurements hinders many analyses. But I leave this point to the authors

- please consider moving Fig. 8 and its description as the first point of sec. 3.1, to first describe where the data were measured, and then what they look like

- please adjust the alignment of the first panel (Watershed with Sediment data) in Fig. 9

- l. 451-452: please explicitly state which EU directives

- l. 487-490: I agree on the need for data quality assurance and documented procedures. But, from your sentence, it is not fully clear how the “rapid visualization and analysis of temporal distribution and data gaps” in your database contributes towards these aspects. I suggest rephrasing this paragraph

- l. 493-495: please check the language

- l.504: this is the first time you spoke about the “data call”. I suggest adding more comments in the Introduction, as readers might get confused

- l.513-519: you presented here a few significant limitations. What are the plans to address them? I suggest integrating this paragraph with the following one, presenting actionable steps and not remaining too vague. Accountability and bureaucracy might also be major obstacles, and authors are encouraged to provide critical comments on this

This manuscript presents the Italian Fluvial Sediment Transport Database (ISTD), bringing together a large amount of historical and recent hydro-sedimentary information within a common database and web platform. Overall, I find this a useful and timely contribution. Sediment transport data are often scattered across different institutions, projects, and monitoring periods, so having these datasets brought together in one place could become a very useful resource for researchers working on rivers, sediment transport, and river management.

I also appreciate that the manuscript is quite open about the limitations of the current database, particularly the differences in instrumentation, temporal coverage, spatial coverage, and metadata quality. These are not necessarily weaknesses of the database itself, but rather reflect the reality of long-term sediment monitoring. Overall, I am supportive of publication. I do not see major issues with the concept or overall contribution. Most of my comments below are relatively minor and are mainly intended to make the database structure, data processing, and figures easier for future users to understand.

The Methods section gives quite a lot of detail about PostgreSQL and the web platform, but relatively less about how the datasets themselves were collected and prepared before being added to the database. It would be useful to briefly explain the data-curation workflow. For example, how were datasets selected, were units and parameter names standardized, and how were missing metadata or duplicated observations handled? A short paragraph or simple workflow diagram would probably be enough.

Related to this, the manuscript mentions that data validation is carried out during upload, but I was not entirely clear about what this validation includes. It would be useful to briefly explain whether this involves checking dates, units, coordinates, data types, unrealistic values, duplicate records, etc. This would help future users understand how much quality control has already been done before downloading the data.

Figure 1 was not very easy for me to follow in its current form. I understand the general database structure from the text, but the relationships between the different tables are difficult to understand directly from the figure. Perhaps the authors could simplify the figure slightly, make the main pathway from watershed/river to acquisition and then to data more visually obvious, and explain the symbols or relationship types. Grouping the tables into broad categories such as geographic information, measurements, and users may also help.

It may also be useful to provide a simple summary table of the database contents. There are many parameters, instruments, time series, and measurement frequencies discussed throughout the Results. A table showing the main parameters, units, number of records or time series, and approximate temporal coverage would allow readers to understand the database much more quickly.

I also noticed that the numbers shown in the web-interface screenshot in Figure 2 are different from those reported later in the Results. For example, the screenshot shows different numbers of records, stations, and rivers from those described in the manuscript. This may simply be because the online database has continued to grow while the manuscript analyses a frozen version, which is completely understandable. If so, I suggest adding one sentence to make this clear.

Figure 6 contains useful information, but I found it somewhat difficult to interpret quickly. The combination of modal frequency, minimum–maximum range, and cumulative percentage makes the figure quite busy, and the individual parameters cannot easily be identified. Perhaps the authors could simplify the presentation or label the parameters more clearly. The same information could potentially also be separated into two simpler plots.

Figure 7 is also informative, but some panels become very dense and almost completely black because many time series overlap. It may help to explain more clearly what each horizontal row represents and how the time series are ordered. A slightly simplified visualization may also make the temporal gaps and differences among parameters easier to see.

Figures 8 and 9 are generally useful, although some additional geographic context would help readers who are not familiar with Italian river basins. Adding labels for a few of the major basins discussed in the text, such as the Po, Adige, or Arno, would make the figures easier to follow. For Figure 9, it would also be useful to make very clear that the colour scales differ among panels and what exactly the mapped values represent.

The database includes not only sediment transport variables but also hydrological and physico-chemical variables such as discharge, temperature, pH, and electrical conductivity. I actually see this as a strength, because these variables can be important for understanding sediment dynamics. However, perhaps the authors could explain this broader scope a little more clearly when introducing the database.

The manuscript would also benefit from one final careful proofreading. There are several small grammatical and formatting issues throughout the text, as well as some duplicated DOI formatting in the reference list. These are minor and should be straightforward to correct.