General Comments:

This manuscript presents a well-executed and innovative study on baseflow separation in small rural catchments, focusing on the calibration of three Recursive Digital Filters (Eckhardt, Lyne and Hollick, and Chapman and Maxwell). The integration of dissolved silica as a tracer and the event-specific calibration approach are both novel and valuable contributions to the field.

The writing is clear, and engaging, making the technical content accessible and enjoyable to read. The study’s methodology is robust, and the results convincingly demonstrate the advantages of dynamic, event-based calibration-particularly for the Eckhardt filter, which outperforms the others in accuracy when parameters are tailored to rainfall event intensity.

Specific Comments:

While the manuscript is strong overall, there are areas where it could be further improved. The authors provide a thorough explanation of performance metrics such as NSE and RMSE, but this level of detail may be unnecessary for the target audience, who are likely already familiar with these standard evaluation tools. Streamlining these sections would help maintain the manuscript’s focus and momentum. The presentation of results relies heavily on numerical values in the text. Incorporating more plots and figures would greatly enhance the reader’s ability to interpret and appreciate the findings.

This is a timely contribution with clear novelty in its event-specific calibration strategy and use of chemical tracers. The manuscript is exceptionally well-written and methodologically sound. To maximize its impact, I recommend reducing the over-explanation of standard metrics and enhancing the presentation of results with more visual aids. These improvements would make the findings even more accessible and persuasive to a broad hydrology audience.

General Comments

The manuscript describes an analysis in which three baseflow separation methods (specifically types of recursive digital filters) are tested against a silica-based estimate of baseflow for a small watershed in Brazil. The authors compare RDFs fit against the entire dataset as well as RDFs fit to events falling into one of three magnitude categories. The analysis shows that the Eckhardt filter tends to provide better results across events and that the use of categorized parameters can provide some improvement in estimating baseflow across a range of event types.

The work presented is thorough and is explained with a commendable level of detail. The manuscript is organized nicely and is well written, making it easy to quickly understand what was done and the nature of the results. The authors provide a good explanation of the methods and the figures and tables support the interpretation and conclusions given.

One criticism I might offer is that this work is based on and potentially limited in relevance to a single (and comparatively small) watershed.

The manuscript would be more impactful if the value of the analysis is situated in a more generalized context - what about the results would be useful to a researcher or practitioner needing to understand or estimate baseflow somewhere else? I would suggest a potential expansion of the discussion and interpretation to address this broader context a bit more.

Specific and Technical Comments

- While the authors describe the physical characteristics of the watershed, a more specific explanation of the conceptual model of the watershed would be helpful in providing a basis for interpretation of the baseflow separation results. For example, it would be helpful to discuss what the Si data (or other previous work in the watershed) suggests about how baseflow contributes to streamflow. This can be used to provide context for the different methods and their interpretation too.

-  What does the difference in performance from the tiered/categorized RDF parameter fits tell us about (potential) mechanisms in the watershed? This is an interesting result and I would appreciate a little more discussion on the topic.

- The description indicates the area receives relatively consistent precipitation, perhaps more than many other places in the world. This would suggest fairly constant GW levels and perhaps less variation in "old" water. Yet the results show a lot of variability in shape and timing of baseflow. I'm curious how this is to be interpreted, and whether the authors view this tier-type approach as something than can be useful in disentangling seasonal variation in groundwater-surface water connection? Again, some additional discussion addressing this would be appreciated

- Much of the information shown in error metrics tables is repetitive between the two sections of analysis and results. I'd suggest condensing some of this and/or moving some of it to an appendix/supplement. 

- Table 1 (page 8) - Units for Qmax and Qmin are different. Check flow units for consistency.

- Figure 2 and Figure 5 - I appreciate the information density on these plots. However, the line widths on the RDF results (colored lines) came through rather faintly on the PDF I reviewed, making it difficult to readily differentiate among the results. Additionally the figure seemed a bit blurry. To the extent that the line widths and resolution could be adjusted, these figures will be much more effective.

- Line 558: "events 2,9, and 9 showed..."  - I suspect the second "9" was in error here.