Assessing the Impacts of Land Cover and Climate Changes on Streamflow Dynamics in the Río Negro Basin (Colombia) Under Present and Future Scenarios

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

1) A brief summary

The manuscript investigates the combined impacts of land use/land cover change and climate change on streamflow dynamics in the Rio Negro Basin (Antioquia, Colombia). The authors integrate multisensor remote sensing, land use modeling based on artificial intelligence, CMIP6 climate scenarios (MPI-ESM under SSP2-4.5, SSP3-7.0, and SSP5-8.5), and the distributed hydrological model TETIS. Three land use scenarios (optimistic, trend, and pessimistic) were simulated up to 2060 and combined with climate projections to assess hydrological responses. The results show that urban expansion and deforestation increase flood peaks and reduce baseflow, while conservation scenarios favor hydrological regulation and groundwater recharge. The study provides a replicable methodological framework for Andean basins with scarce data availability.

 

2) General concept comments

The study is innovative in integrating land use modeling with artificial intelligence, downscaled climate projections, and the TETIS model, which is highly relevant for tropical mountain basins. The approach is significant because it relates anthropogenic pressures to hydrological extremes under future scenarios. The manuscript is detailed and well structured, though in some sections the highly technical language may reduce accessibility for non-specialist readers. A more concise presentation of the methods, with greater emphasis on the implications, would improve the flow.

A strong point is the replicability for other Andean basins, but it would be valuable to highlight the novelty of the methodological integration (AI + TETIS + CMIP6) in the abstract. Furthermore, the discussion should more explicitly address the limitations of the modeling process, such as reliance on historical transitions, classification errors in land cover datasets, and the absence of institutional, legal, or socioeconomic drivers in the projections. This would provide a better balance between methodological innovation and applied realism.

 

3) Specific comments

Relocate Figure 1 to the Study Area (Rio Negro Basin) section, placing this section before the methodology description to improve reader understanding.

Provide clearer definitions for hydrological indicators such as Q90/Q10, which may not be familiar to international readers.

Although the NSE values (>0.85) demonstrate robustness, it would be useful to include a brief comparison with results from other hydrological models applied in the region (e.g., SWAT, HBV, VIC), thereby justifying the choice of TETIS.

In the discussion, expand the comparison with other Andean basins (Ecuador, Peru, Bolivia) that have also reported baseflow reductions following deforestation and increased imperviousness. The intensity of these effects may vary with altitude, soil type, and forest cover.

The three land use scenarios (optimistic, trend, pessimistic) could be better contextualized by referencing similar prospective modeling efforts in tropical regions, such as the Amazon and the Ecuadorian/Peruvian Andes, highlighting methodological convergences (LCM, neural networks, Markov chains) and differences in legal or policy constraints.

Include a dedicated section/paragraph on uncertainties, addressing classification errors, variability among simulation runs, and the absence of non-modeled drivers (agricultural subsidies, conservation areas, environmental policies).

The conclusion could be made more concise and should end with a clear, practical message for policymakers and water managers.

Author Response

Please see cover letter. Thank you.

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

Reviewer Comments for hydrology-3904573

This study projected the impacts of land use change and climate change on the hydrology of Columbia’s Río Negro Basin using a calibrated model. I found the writing to be clear and easy to follow, and the findings to be pressing and important. I think this manuscript makes an exciting contribution to the literature, and my concerns are mostly with the communication of the background and results.

MAJOR COMMENTS:

2. State of the Art. I found this section was very long, with some very long paragraphs, and I think that was partly because of its sentence structure. You frequently use the sentence structure of “[this study] found that… then, [this study] found that…” For example, lines 206-213 describe two studies that found hydrologic responses to land use changes, but it takes 8 lines to write it. If you switch to a structure where you make the scientific statement, and then cite the references at the end of the sentence, I think you could shorten the text substantially. You then may find that some of the statements could be combined, or may even not be needed if they are not pertinent to the flow of the paragraph. For example, the lines 206-213 sentences could be written as something like “Tropical Andean watersheds respond hydrologically to land use changes, such as deforestation, cropland, and pasture impacting runoff, infiltration, and seasonal water availability [22,23]” which is a lot shorter (maybe 2-3 lines). This could help make some of the very long paragraphs more concise, such as lines 191-239. I suggest restructuring most the affected sentences in this section and throughout the manuscript in this way to make the text more concise and make it easier to find the most important take-aways.

3.2.1 Overview of Methods – I really like section, as it lays out the study well, but it took me a while to get to it because of the long writing I mentioned above. I think if you make the changes to sentence structure I recommended, that would bring this important overview forward and really highlight what the study is doing up front.

Lines 437-474. Is your land cover classification, harmonization, and projection approach with the neural network able to account for potential seasonal variation in land cover data? For instance, if you used many individual instances of satellite data over the course of the year, could there be the potential for seasonal inconsistencies to account for, which could appear as spurious land cover changes? Since you mention high-resolution satellite imagery research in line 947, and land cover change models in line 1005, it may be helpful to briefly describe how you account for the seasonal variation and potential spurious or inconsistent land cover change estimates, especially around land cover transitions. Or, you could briefly discuss it as a limitation or research need if you believe it is pertinent.

Lines 584-590. For reproducibility, could you provide more details about these correction factor adjustments? Like, were there any specific parameters or factors adjusted, and what were they adjusted by?

5. Results. There are a lot of results figures (Figures 3-14), each with many sub-panels, which is fine, but it makes it hard for me to pick out the main take-away findings that were most important to the conclusions. To help with this, I suggest adding a conceptual diagram or flowchart in the Discussion or Conclusions section that summarizes the key results points you want readers to remember. It could show a relatively simple process, for example that you simulated climate and land cover scenarios in a calibrated hydrologic model, found that land cover change affected future hydrologic regimes and climate change impacted more extreme flows, and want readers to remember that land management such as forest preservation is really important. Maybe with some simple artwork or images. This could help communicate the main findings and the impact of the work, which can get lost in a large number of multi-panel results figures.

MINOR COMMENTS:

Table 1. I found this table to be very helpful.

Figure 4. The labels are too small for me to read. Could you make them larger? (more similar in font size to the manuscript text). Same for Figure 5, 6, 7, 8, 9, 10, 11, 13, and 14 labels.

Figure 8. Are you able to adjust these plots so that the relationship is more apparent, rather than showing big blue blobs of dots? For instance, you could make the dots semi-transparent, or potentially consider what it looks in log-log scale if that makes it easier to see.

6.4. Methodological Limitations and Uncertainties. I really liked the communication of uncertainties, as well as providing multiple scenarios for the changes. 

Lines 867-868. Yes, maintaining forests in headwaters does sound important. Good take-away.

Thank you for the opportunity to learn about this exciting study. I wish you the best with this manuscript and your future endeavors.

Author Response

Please see cover letter. Thank you.

Author Response File: Author Response.pdf

Round 2

Reviewer 2 Report

Comments and Suggestions for Authors

The authors satisfactorily addressed my previous comments. I have no further concerns. I especially like the take-aways for decision makers about the importance of land preservation and restoration.

Dan Myers