Hydrological Response to Predominant Land Use and Land Cover in the Colombian Andes at the Micro-Watershed Scale

COMENTARIOS GENERALES

LÍNEA DE
NÚMEROS

·         Este artículo es un trabajo de hidrología muy completo e interesante, basado en observaciones de campo cuya reproducibilidad se pretende establecer comparándola con los resultados de la modelización hidrológica.

·         Se documentaron tres cultivos de cobertura vegetal diferentes durante más de tres años con una repetición en dos sitios diferentes, lo que permitió realizar más comparaciones.

·         Los resultados son muy completos y todos los elementos del ciclo hidrológico están bien tenidos en cuenta y cuantificados a escala mensual.

·         La Figura 12 concluye los resultados y su discusión con una presentación de todos los parámetros hidrológicos (lluvia, escorrentía, evapotranspiración y contenido de agua del suelo) y su evolución en las 6 subcuencas durante todo el período: ¡un excelente trabajo hidrológico!

·         El revisor lamenta que la discusión no incluya ninguna comparación con otros estudios comparables en los Andes u otras montañas (Alpes, Pirineos, Apeninos), particularmente las tropicales (Sierra Madre Occidental, cordilleras de África Oriental y Sudafricana, montañas del Sudeste Asiático).

Estimado revisor: “A la luz del comentario mencionado anteriormente, se incorporaron en la sección de resultados y discusión varias referencias y breves discusiones de investigaciones realizadas en los sitios y áreas geográficas sugeridos”

·         But apart from this shortcoming, this work is serious and well supported by real observations on the ground.

-

SOME SPECIFIC OBSERVATIONS AND RESPONSE

1. Figure 1: Sharpening, especially for the caption!

102

·         The reviewer's suggestions were duly considered and figure 1 caption in the manuscript were adjusted accordingly and are presented herewith.

2. Figure 2 : Sharpen photos! Increase the dpi

192-193

·         The reviewer's suggestions were duly considered and figure 2 (now figure 3) dpi were increased and format adjusted.

3. Line 150 to 156 : explain the reasons why you choose this model (TETIS) and what are its advantages and disadvantages, and its efficiency in tropical mountain areas.

136-163

The reviewer's suggestions were duly considered and we added to materials and methods a section to explain the main reason to choose TETIS model, advantages and disadvantages, and efficiency in tropical mountain areas. Please see respective lines

4. Tables 3, 4 and 5 : change Tabla by Table

216, 376 & 398

·         The recommended adjustments were implemented, and caption table were changed to according language.

5. Figures 4 and 6 (now, figures 6 and 8) : in the figure, change BN with NF and SA-c with AS-c

436, 482

·         The recommended adjustments were implemented, and the incorrect labels were changed to according land uses.

6. Figure 6 (now figure 8) : change “aforados” with measured

482

·         The recommended adjustments were implemented, and the incorrect labels were changed to according suggestions.

7. Line 510 : change « land use type due the favorable effects » with « land use type due to the favorable effects »

·         The recommended adjustments were implemented, and the incorrect sentences were changed to according suggestions.

550

8. Why didn’t you use the specific flow (l/s/km²) to avoid being influenced by the size of the watershed?

· Se trata de áreas de pequeñas microcuencas que fluctúan entre 0,105 km² y 0,515 km². Tienen una red de drenaje o afluentes muy pequeños, en su mayoría de orden 0 y 1. Esto las convierte prácticamente en cuencas de cabecera. Esto significa que su rendimiento hídrico por unidad de superficie es probablemente muy variable. El caudal no era de interés en este contexto. El objeto central de la investigación hizo hincapié en los caudales medios y mínimos. Estos últimos son contribuciones importantes al caudal total. Otra cosa a tener en cuenta es que cuando elegimos las microcuencas experimentales, tratamos de encontrar aquellas en las que al menos el 60-70% del área estuviera cubierta o se utilizara para algo. Esto no era necesariamente todo en un solo lugar, porque queríamos centrarnos en el objeto central de contraste y su respuesta hidrológica asociada en esta investigación. Otra cosa a tener en cuenta es que en las pequeñas cuencas de cabecera de montaña, puede ser complicado averiguar cuánta agua proviene del subsuelo. A veces, ni siquiera sabemos si esa agua está llegando a la zona de drenaje de la cuenca, y no siempre es fácil entender cómo se relaciona eso con los flujos superficiales que afectan la respuesta hidrológica y el propio rendimiento hídrico.

9. BH debe cambiarse por WB (líneas 86, 87 y 662)

· Se implementaron los ajustes recomendados y se cambiaron las oraciones incorrectas de acuerdo a las sugerencias.

74,77,79,592

GENERAL COMMENTS

LINE
NUMBERS

·         Overall, the ms." Hydrological response to predominant land uses in the Colombian Andes at the micro-watershed scale" is comprehensive and well-structured. It provides a detailed analysis of the hydrological responses in different land use types within the Colombian Andes, supported by robust data collection, modeling, and analysis. Here are some specific observations and suggestions for improvement:

SOME SPECIFIC OBSERVATIONS AND RESPONSE

1. The abstract contains abbreviations that need to be defined upon their first occurrence to ensure clarity for all readers. Please spell out each abbreviation the first time it is used. The abstract provides a concise summary of the study's objectives, methods, results, and conclusions. However, it would benefit from a brief mention of the significance or implications of the findings to highlight the study's contribution to the field.

11-24

·         The reviewers' suggestions have been duly taken into account. The abstract and abbreviations have been adjusted accordingly.

2. The keywords section currently repeats terms from the title, which limits the manuscript's discoverability. Consider including additional keywords that capture the core aspects of your study and related concepts not covered in the title. For example: land use change, Hydrological modeling, Watershed management, soil erosion...etc...

25-26

·         The reviewer's suggestions were duly considered and keywords have been adjusted accordingly.

3. Introduction: The introduction provides foundation for the study, but clarity and readability can be improved through concise and precise language. With these refinements, the introduction will more effectively set the stage for the research presented in the manuscript.

4. L29-34: The first sentence is quite dense and could be simplified for better readability. Consider breaking it into two sentences.

29-33

·         The sentences were duly changed and adjusted the manuscript readability in this section.

5. L36-39: This sentence is clear but could be expanded slightly to better explain the factors influencing hydrological response. For example: "The hydrological response to a storm rainfall event depends on the interaction of climate, soil properties, and land use changes. Key determinants include hydraulic conductivity at different soil depths, the distribution and duration of rainfall, and slope morphology. The geographical location of the watershed also significantly influences its hydrological response".

34-37

·         The sentences were duly changed and adjusted the manuscript readability in this section.

6. L44-46: This statement is a bit repetitive. It might be better integrated into the previous or following sentences. Suggestion: "Therefore, understanding the degree of complexity and nonlinearity that characterizes hydrological behavior in response to climate variability is crucial for advanced modeling and analysis of the rainfall-runoff relationship." 

41-43

·         The sentences were duly changed and adjusted the manuscript readability in this section.

7. L48: "Some authors"....please, references here

L48-53: This paragraph could be made clearer by focusing on how soil moisture content and other factors influence hydrological response.

44-49

·         The sentences were duly changed and adjusted the manuscript readability in this section.

8. L54-56: This sentence effectively introduces hydrological modeling as a tool but could be simplified. I suggest: "Suggestion: "Hydrological modeling has become essential for understanding the complex interactions of physical, hydrological, and ecohydrological processes, moving beyond the traditional linear approach of viewing hydrological response simply as the conversion of precipitation to runoff."

49-52

·         The sentences were duly changed and adjusted the manuscript readability in this section.

9. L58-65: This paragraph provides a good overview of hydrological models but could be streamlined for clarity. Suggestion: "Hydrological models, simplified representations of natural systems, can be classified as physical process-based or conceptual. Conceptual models use mathematical or physical formulas to represent processes, while physical models describe natural systems using prototypes with mathematical representations based on the laws of conservation of mass, momentum, and energy. These models can be empirical or theoretical and classified as stochastic or deterministic. In natural process modeling, models can be aggregated or distributed based on the level of discretization used to describe watershed characteristics, such as the spatial variability of input parameters."

53-60

·         The paragraph were duly changed and adjusted the manuscript readability in this section.

10. L67-73: The description of conceptual aggregate models is clear but could benefit from more specificity about their application.

61-67

·         The suggestion were duly considered and this section were adjusted, please see the respective lines.

11. L75-82: This section discusses the evolution of the TETIS model and the use of HRUs. It could be clearer and more concise. I have a suggestion: "TETIS has evolved from an aggregated model to a distributed model, where watersheds are subdivided into Hydrological Response Units (HRUs), representative slopes, and subwatersheds. Using experimental basins and HRUs with smaller extensions is recommended for advancing hydrological modeling. This approach allows for the aggregation and integration of hydrological responses through a network of channels at the watershed level. However, it requires a detailed understanding of the spatial and temporal variability of hydrological response and more comprehensive data, input information, and model parameters."

68-73

·         The paragraph were duly changed and adjusted the manuscript readability in this section.

12. L92-96: The objective of the study is clear but could be stated more succinctly. My suggestion: "The main objective of this study is to evaluate the hydrological response in Andean river basins according to different land uses, daily flow regimes, and base flow responses through hydrological monitoring and the TETIS simulation model. This will enhance integrated water resource management in tropical Andean contexts."

82-85

·         The main objective were duly changed and adjusted the manuscript readability in this section.

13. The section is comprehensive and detailed, providing clear descriptions of the study area, experimental setup, and data analysis methods. However, some sentences could be made clearer, and minor grammatical corrections are needed. Additionally, consider adding more visual aids (like diagrams or flowcharts) where complex procedures are described.

306

·         The suggestions were duly adjusted and we designed manuscript’s flow chart added in this section

14. L99-108: This section is generally clear but could be more concise. The description of the experimental micro-watersheds (EMs) could be streamlined for better readability. Suggestion: "This research was conducted in six experimental micro-watersheds (EMs) within the Combeima and Cali River basins, located in the Tolima and Valle del Cauca departments of the central Andean region of Colombia. The EMs, situated between 1250 m and 2350 m elevation, were categorized into three land use classes: natural forest (NF), pasture (P), and coffee agroforestry system (AS-c). Figure 1 shows the distribution of the EMs (Santa Lucía 1 (SL1), Santa Lucía 2 (SL2), Mojarra (MOJ), Faro (FO), Farito (FTO), and Cristo Rey (CR)), their respective land uses, and the instrumentation setup."

88-99

·         The suggestions were duly changed and adjusted the manuscript readability in this section.

15. Please, take a note that Figure 2 is mentioned in the text. PLease, provide it.

193

The suggestions were duly and Figure 2 has been mentioned (Now figure 3a-h)

16. L189-202: The initial conditions and calibration parameters section is clear but could benefit from more context on the iterative adjustment process. I suggest: "Initial storage conditions for the model's four tanks were defined based on soil hydro-physical characteristics. Model parameters were iteratively adjusted to achieve physical consistency and the best fit between observed and simulated flows. Agreement was sought between the model-produced water volumes and those observed in each micro-basin. Gauging datasets from each EM were used to recalibrate the model, enhancing the accuracy of the predicted Q values."

210-215

The suggestions were duly considered and adjusted the manuscript readability in this section.

17. L221-231: This section is clear but could benefit from more context on the significance of these indices. For example: "The Moisture Retention and Regulation Index (IRH) and Base Flow Index (IFB) were calculated to explain soil moisture regulation and its impact on flow behavior. IRH was derived from the ratio between the volume below the mean flow line and the total volume under the FDCs. Higher IRH values indicate greater moisture retention and regulation. The IFB was calculated to quantify the contribution of base flow to total flow, using a method based on Nathan and McMahon [28] and Lim et al. [29]."

239-245

The suggestions were duly considered and adjusted the manuscript readability in this section.

Results: is well-structured and provides detailed descriptions of the results, their interpretation, and conclusions. However, some areas can be made clearer, and minor grammatical corrections are needed.

312-542

In response to this suggestion, the first 6 aspects of the results were revised and adjusted from point 3.1 to point 3.2.4, including some grammatical clarifications.

Conclusions: The conclusions are well-structured and provide a concise summary of the key findings from the study. However, some areas could benefit from clearer language and more precise descriptions. Additionally, the conclusions should more explicitly highlight the broader implications of the findings and potential areas for future research.

695-740

The suggestions were duly considered and adjusted the manuscript readability in this section.

GENERAL COMMENTS

LINE
NUMBERS

·         Your research is crucial for understanding the impacts of land use on hydrological processes. This study provides valuable insights into the relationship between different land uses and their hydrological responses. I have several comments and suggestions that would enhance the methodology and analysis of your study.

·         I appreciate your valuable work and believe that addressing these comments and suggestions will enhance the robustness and applicability of your research.

SOME SPECIFIC OBSERVATIONS AND RESPONSE

1. C1. The use of the TETIS model to evaluate the hydrological response is a robust approach. However, ensuring that the initial storage conditions and model parameters are accurately defined is also very crucial. How did you ensure the reliability and accuracy of these parameters? It is suggested to provide more details on how these parameters were obtained and validated to ensure the reliability of your model results.

·         We wanted to make sure that the Tetis model was working properly and that the data we were using was accurate. So, we based this study on the results from previous doctoral research conducted by the main author of this manuscript. This allowed us to publish an article that looked at how water behaves in the soil in different land covers and land uses, as well as in watersheds. (Garzón et al., 2021).

·         Thanks to all that great previous research, we were able to analyze and evaluate a bunch of different variables related to texture, porosity, bulk, particle density, moisture retention curves, and gravimetric moisture content. But the really important stuff was measuring and monitoring the volumetric water content in the soil in the field and then validating it in the lab for different depths (from the surface down to 1.60 meters). All of that gave us some great starting points and key references for getting the initial storage conditions and TETIS model parameters just right. This modeling exercise was also supported by the discussion and joint analysis with the co-authors of the article and this manuscript, by their experiences and expert judgment, and by references provided by the state of the art literature on these topics (relatively scarce) for the case of soils and predominant land uses in the central Andean region of Colombia.

2. C2. Your study considers various environmental variables, including rainfall, soil, and land cover. While these factors are essential, incorporating additional variables such as land management practices and socio-economic factors could provide a more comprehensive analysis. It is suggested to include these additional variables in future studies to enhance the robustness of your analysis.

·         I couldn't agree more! I just wanted to make a quick note about the importance of variables related to the management of forest cover and land use. It's so important to monitor and follow up on the natural cover and its levels of intervention, as well as successional dynamics and the phenological stages of the species and the forest ecosystem complex itself. I'm happy to report that we've identified some key variables related to the use and management of pastures and the agroforestry system with coffee. These include pasture management-rotation and fertilization, pruning management and nutrient recycling of the agroforestry system with coffee, and the use and management of water for the various productive activities. Likewise, the size and tenure of properties and the types of owners play a big role in many of the diverse intervention-production activities on small and medium-scale properties in the central region of the Colombian Andes. These activities are influenced by the dynamics of variables and processes of Andean-tropical contexts in Latin America, Africa, Asia, and other tropical regions around the globe.

3. C3. The calibration and verification of the TETIS model show varying degrees of fit between observed and simulated flows. For micro-basins SL1 and SL2, the fit appears to be poor. What are the potential reasons for this discrepancy? It is suggested to explore potential reasons for this discrepancy and consider additional calibration steps or alternative modeling approaches to improve model performance.

·         We think the reason might be linked to some flood events that happened in SL1, which caused some changes in the registration of the level sensors for flow calculation over several days. These floods were not the focus of our previous research, which was to monitor and track the dynamics and behavior of average and minimum flows. Unfortunately, this did affect the normal operation of the overflow level control sensor for flow level registration for a few days. However, we did our best to clean, adjust and calibrate the reference level and overflow in the respective weir-wall. This was more the case in SL1, bless its heart. On top of that, it seems that SL1 has a larger drained area and a slightly greater slope gradient than SL2, which probably contributed to a slightly greater flow differential or variation in SL1 than in SL2. Another possible reason could be attributed to possible variations or losses of flow by percolation. SL1 has slightly sandier soils than SL2, but this is not easy to control and monitor. It wasn't a priority of detail within the main objective of this research, but it's still something we'd love to look into further if we get the opportunity.

·         Another possible reason is that little is known about the dynamics and behavior of percolation flows at greater depths that contribute to the understanding of groundwater flows and contributions to possible aquifers that could be or could be considered “hanging” in both SL1 and SL2; this tank or component being one of the tanks taken into account and analyzed by the TETIS model.

4. C4. The use of observed flow data to verify the model is commendable. However, how did you address potential sources of error in these measurements, such as instrument precision and data recording intervals among many others? Hence it is suggested to discuss how these potential errors were mitigated to ensure data accuracy.

·         In the verification and permanent follow-up of the data records/measurement values of the sensors' flow rates, adjusted with atmospheric pressure values, the measurement and comparison of these data was complemented with the installation of limnimetric rulers in each weir wall, in addition to the level sensors for flow rate, flow measurements were made with micro-metering and volumetric gauging for the control and detailed verification of the flow because of the very low flows, from the sub-daily levels, with basic registration every 5 minutes, and gauging with micro-metering and volumetric gauging in the field every 15 days on average, in each use-microbasin.

5. C5. The model performance evaluation metrics (R2, RMSE, NSE, BE) provide a quantitative assessment of model accuracy. While the NSE values are moderate to high for some micro-basins, others show poor performance. It is suggested to conduct a more detailed analysis of why certain micro-basins perform better than others and how model accuracy can be improved. What specific factors might contribute to these differences in model performance?

·         Once the initial conditions and parameters required by the TETIS model were defined and calibrated, and the metric indicators were obtained, the optimal adjustments were identified for CR/P, MOJ/AS-c, and FTO/AS-c. Conversely, the least optimal adjustments were identified for FO/NF, followed by SL1/NF and SL2/P.     

• One potential factor influencing these outcomes is the alteration of the OF SET reference level in the sensor-level record (base and support for flow calculation) during periods of rainfall associated with extreme events. This occurred on multiple occasions in larger microbasins with forest cover (NF), in FO in Cali, and in SL1 in Combeima. This phenomenon was observed with minimal to no incidence in the MOJ/SA-c, FTO/SA-c, and CR/P microbasins. It is also possible that this alteration was associated with the fact that both FO/NF and SL1/NF, which have larger areas than the other microbasins, had a higher flow rate.
• While the drained area is generally acknowledged to contribute to the formation of the flow, it can be argued that, given the level gradients and the prevalence of high slopes in these microbasins, the contributions from surface flows, and potentially those from base and subsurface flows, may be more significant in the larger microbasins. Therefore, the contribution to flow from surface flows and interaction with subsurface flows, baseflow, and groundwater is subject to greater variability and irregularity, which can affect the metric indicators.
• Specific factors warranting improvement include ensuring greater follow-up to the registration and checking of the reference OF SET in the event of a tendency toward extreme rainfall. It is important to distinguish between high intensity rainfall events and those of lesser intensity, for example, events of between 50-100 mm/hour. Events of a very extreme nature have not been the subject of sufficient interest. Furthermore, there is a need for a more rigorous level of maintenance and immediate cleaning the day after the events. It is essential to establish and enhance the level of instrumentation to gain a more comprehensive understanding of subsurface flows, including lateral and interflow dynamics, which contribute to base flow patterns. This will facilitate advancements in our knowledge and enhance our comprehension of subsurface flows.
• These aspects are of significance due to the necessity and fundamental objective of the Model, which aims to integrate or weigh the interaction between the dynamics and behavior of how the flows intersect vertically and horizontally in the formation of the total flow. This is the product of the interaction of hortonian-capillary and surface runoff flows, infiltration flows that explain intermediate subsurface gravity flows and base flows, and percolation flows that explain subway flows. This is even in the context of the potential presence of interacting aquifers.    

6. C6. Your study has highlighted significant differences in precipitation and flow patterns between the Combeima and Cali River basins. It is therefore suggested to include a more detailed discussion on the potential drivers of these differences, such as microclimatic and orographic factors. How do these factors influence the hydrological responses in your study areas?

·         The precipitation regimes that occur in the Combeima and Cali river basins are essentially of an orographic type that originate in the inter-Andean valleys in the central zone of Colombia in sectors of the middle basin of the Magdalena river in the case of the Combeima river basin and in the upper Cauca basin in the case of the Cali river basin; but once these orographic fronts enter and pass through the Combeima and Cali river basins, in the case of Combeima, due to the predominant relief of medium and high mountains and the presence of canyons or very narrow gorges, these fronts contribute to the formation of rain fronts of significant amounts that fluctuate between 1578 - 2353 mm for Combeima in altitude gradients between 1590 and 2322 m. a.s.l. for Combeima and between 1340 - 1892 mm for Cali, in an altitudinal gradient between 1266 and 1764 m.a.s.l.; which together with a lower temperature gradient in Combeima basins of 20.8 degrees average and 25.4 in Cali river basins, and a greater presence of forest and semi-natural vegetation and agroforestry systems with coffee in Combeima basin that contribute to form horizontal precipitation fronts associated with cloud forests [1,2].  In Guatemala, in its largest area of cloud forests and the Biosphere “Reserva de Minas”, and in the Colombian Orinoquia, the significance and contribution of horizontal precipitation to the flow has been studied, and even the sensitization that this form and contribution of rainfall can generate to the fundamental variable and input that explains the hydrological response.

·         Together, these orographic and environmental factors or variables are considered to influence and explain the higher rainfall in the Combeima river basin than in the Cali river basin. Part of this behavior may also be influenced by the presence and formation in some periods of the year of very localized convective rain fronts in some sectors with a higher frequency in the Combeima river basin than in the Cali river basin. Because of this variability, the Combeima river basins have a higher pluviometric regime during the study period than the Cali river basin, in addition to the orographic aspects, it is necessary to take into account the interaction of soil types and drainage areas, These systemic factors help to explain a higher average flow regime in the Combeima basins, particularly in the basin with pasture use, a very similar value in the basins with agroforestry system uses in both Combeima and Cali, and a slightly higher average flow in the case of the basin with forest in the Cali river basin. [3–5].

1. Morales-de la Cruz, M.; Francés, F. Hydrological modelling of the “Sierra de las Minas” in Guatemala, by using a conceptual distributed model and considering the lack of data. In Geo-Environment and Landscape Evolution III; WIT Press: Southampton, UK, 2008; pp 97–106. doi:10.2495/GEO080101.

2. Ramírez, B. H.; Teuling, A. J.; Ganzeveld, L.; Hegger, Z.; Leemans, R. Tropical Montane Cloud Forests: Hydrometeorological variability in three neighbouring catchments with different forest cover. Journal of Hydrology 2017, 552, 151–167. doi:10.1016/j.jhydrol.2017.06.023.

3. Montealegre, J. E. Estudio de La Variabilidad Climática de La Precipitación En Colombia Asociada a Procesos Oceánicos y Atmosféricos de Meso y Gran Escala.; Bogotá, 2009.

4. Ruiz, D.; Martinson, D. G.; Vergara, W. Trends, stability and stress in the Colombian Central Andes. Climatic Change 2012, 112(3), 717–732. doi:10.1007/s10584-011-0228-0.

5. Jaramillo-Robledo, A.; Chaves-Córdoba, B. DISTRIBUCIÓN DE LA PRECIPITACIÓN EN COLOMBIA ANALIZADA MEDIANTE CONGLOMERACIÓN ESTADÍSTICA; 2000; Vol. 51.

7. C7. The use of flow duration curves (FDCs) to analyze the distribution of flow values over time is a strong point. In this context, it is suggested to provide more context on how these curves can be interpreted in terms of hydrological behavior and land use impacts. How do the FDCs reflect the hydrological differences between the land use types in your study?

·         In the analysis and interpretation of the CDF, it is essential to try to explain the close systemic interaction between climatological and physiographic variables and processes, highlighting the close relationship that exists between the dynamics and behavior of the rainfall regime (explained by the interaction of temperature, wind, altitudinal gradient, relative humidity, and the adiabatic fronts of dryness and humidity) and once this falls to the surface with the geoform and slope, type of natural vegetation cover and/or land uses present, and the adiabatic pressure fronts of dry tendency and humidity) and once this falls to the surface with the geoform and slope, the type of natural vegetation cover and/or the land uses present, as well as the type of soils and the processes of infiltration, retention-storage and percolation as essential functions of water movement in the soil. It is reiterated that being able to understand these dynamics and behavior in the CDF in a systemic eco-hydrological context is fundamental. Furthermore, being able to do so in the context of the analysis and behavior of hydrological response units also contributes significantly to the understanding of CDFs.

·         In this context, it was found in the response and hydrological modeling in the basins under study, that in most of them there is a significant variation in mean flows, in the first percentiles between 0 and 20% of exceedance in the microbasins and uses in FO in NF and MOJ in ASc, a smaller variation in the first percentile between 0 and 10 % in SL1 in NF and SL2 in P and between 0 and 5% much smaller slope and variation in the mean flows in the FDC in CR in P and FTO in ASc at the first moment of calibration and application of the Model and a notable smaller variation in the mean flows once the Model is recalibrated or verified.

8. C8. Your results have indicated that natural forest covers provide better hydrological regulation compared to pastures and coffee agroforestry systems. I suggest you to discuss the practical implications of these findings for land use planning and watershed management in the region. What specific recommendations can be made based on your findings?

·         The practical implications derived from the better hydrological regulation of natural forest covers provide important elements to be considered in research that may be related to the decomposition processes of mulch or leaf litter typical of the natural and semi-natural covers existing in the Colombian Andean context, with the mineralization rates and nutrient recycling. These processes are related in the context of water movement in the soil, with the processes of infiltration, retention - storage and percolation through the profiles and depths of the soils. It provides elements to be considered in the planning and integrated management of the forest ecosystem complex, miscellaneous lands or mixtures dominated by natural and semi-natural matrixes of vegetation patches typical of forest ecosystems and natural or established agroforestry systems.

·         In this way, it provides elements to be considered in order to reorient strategies and management practices based on nature regarding integrated land use and management, integrated water resource management and watershed management. In this sense, it is recommended that more comprehensive strategies and actions be reviewed and reoriented in forest management plans, environmental management plans for protected areas, conservation, and ecosystem restoration plans, and plans for payments for environmental and ecosystem services, highlighting hydrological regulation as an essential aspect because water is a vital resource. In the context of integrated planning and management plans for water and soil, ecosystems, watershed, and territory, understanding this as an integrated whole.

9. C9. Your study uses daily precipitation and temperature data for model input. Cant you explore the use of higher resolution temporal data, if available, to capture more detailed hydrological dynamics and improve model accuracy. How might higher resolution data affect the model's performance and the interpretation of your results???

·         In light of the fact that this research process has yielded information at the hourly level for both rainfall and observed flows, and that the values of average daily temperature for the microbasins are unfortunately lacking in hourly records within the study area, the modelling was tested with the aggregated version of TETIS. The same initial storage conditions and parameter values used in the calibration were employed for the CR/P microbasins in the Cali river basin and for MOJ/AS-c in the Combeima basin, given that these basins exhibited the most optimal correspondences and fit between observed and expected flows. However, and in partial accordance with expectations, upon executing the model and applying the metric indicators to the resulting outputs, the anticipated outcomes were not achieved. Instead, the tests and goodness of fit demonstrated the least favorable results. This is illustrated in the subsequent image, which depicts the outputs generated by the model and the corresponding values of the metric indicators obtained through this process.

·         The exercise shows that the version of the TETIS model used in this research is probably not satisfactorily adapted to higher resolution time scales, in this case the hourly scale, since it is clear that it would be necessary to provide the model with hourly temperature information, and therefore the model, which automatically generates and applies evapotranspiration values as a key variable, does not synchronize it to the same hourly scale, which in principle would be the most appropriate one. Therefore, it can be concluded that it is not justified in this case, nor is it possible to improve the modeling results by using a higher temporal resolution. Future research should explore the use of more recent versions of the TETIS model, or possibly consider looking for another model that is better suited to provide information at higher resolution time scales and to generate and have the essential primary thematic information required by the particular model being applied.

·         In summary, it is practically improbable to revise and adapt the model and claim to have better levels of accuracy without standardizing all information related to key model input data such as precipitation, temperature, and observed streamflow; the values or references of the initial conditions and parameters to the same levels; and scalar standardization and/or higher temporal resolution for the recalibration and application of the model.

10. C10. The model's sensitivity to input parameters such as hydraulic conductivity and soil moisture is not thoroughly discussed.... It is suggested to conduct a sensitivity analysis to understand how variations in these parameters affect model outputs and to identify critical parameters for accurate hydrological modeling. How sensitive is your model to these input parameters, and what are the implications for your study's conclusions???

·         It is first necessary to acknowledge that no procedure related to the sensitivity analysis of the TETIS modeling has been undertaken. This analysis can be conducted from the outset, when the model is first run and calibrated. This allows for the robustness and quality of the information to be reviewed, including the variables that are considered fundamental inputs of the rainfall-runoff model, such as precipitation, temperature, and, depending on this, evapotranspiration generated internally by the model. This is because the model integrates the water balance as a support of the model structure.

·         A sensitivity analysis can be conducted with respect to the calibration and the initial moisture conditions, including capillary, surface level, and gravity storage in the layers closest to the surface and in the most distant from the surface. This analysis is closely related to the antecedent moisture condition and to the parameters related to the characteristics of the basin in terms of its maximum capillary storage capacity. The residence times of water in surface, subsurface, and subway storage elements, as well as the hydraulic conductivities in tanks at the layer closest to the surface and the deepest and most distant from the surface, can be considered in the analysis. Additionally, the losses due to subway flows can be incorporated. The challenge lies in ensuring a sufficient level of supporting information for all these elements.

·         In this context, it should be noted that the initial conditions of water storage in the soil, or state variables at the time of calibration and verification of the model, were defined based on the previous characterization of hydrophysical variables. These included moisture retention curves, gravimetric water content in the laboratory, volumetric water content measured and monitored in the field, and the bulk density and porosity of the soils. Together, these variables allowed for the approximate definition of initial quantities and their ranges of variation. This information, along with other data from detailed studies on the soils of the Combeima and Cali river basins in the Tolima and Valle del Cauca regions (Garzón et al., 2021 [1]), was used as a reference to approximate the definition of values for some parameters. It was noted that there is still a lack of key information and support for this type of research in the central Andean context of Colombia.

·         The above response is accompanied by an attachment on the global sensitivity analysis of the input parameters and initial conditions of the TETIS hydrologic model. In addition, introductory elements, materials, methods, results and discussion are briefly provided.

11. C11. Your paper has provided a thorough evaluation of hydrological responses to different land uses. However, the generalizability of these findings to other regions with different ecological and climatic conditions is not addressed. It is therefore suggested to discuss how the methodology and findings could be adapted to other contexts. How can your approach be applied to other regions, and what adjustments would be necessary?

·         Based on the fact that this research took into account two substantive methodological references, which were the paired basins of the Coweeta Hydrologic Laboratory - CHL - USA, (Bates and Henry 1928 in Andréassian, 2004; Hewlett 1971, Bosch & Hewlett, 1982 for about a century for this type of research), and in direct field experimentation of the interaction water-soil-plant-man, surrounding basins were selected in principle in similar physiographic and climatological conditions. However, it is essential to recognize that the soil is an essentially variable element of nature that can change from one place to another, in addition to the fact that, at present, climate and hydrological variability in its articulation and manifestation of micro-climatic - meso-climatic and macro-climatic variables associated with ENSO is not sufficiently monitored or known in many tropical areas; Therefore, it is essential to maintain these methodological references and approach that although it is true that there are many proposals, development and conceptual and methodological approaches at a global level, we should try to know as much and better as possible these interrelationships that in physical, hydrological and eco-hydrological context, will allow us to know the hydrological response of each region and ecosystemic environment of the variability of the tropics and the state of the American tropics and even better of the Colombian tropical Andean environment. Then, to know more closely the types of soil, its hydrophysical behavior, the movement of water in the soil, and the dynamics and behavior of these variables and the processes that occur in the relationship of surface - subsurface - intersurface - baseflow - baseflow and groundwater flows, still demand a lot of knowledge and research.

·         We consider that this experience could be improved and adapted in future research and in other regions by seeking greater precision in the selection of MSs in aspects related to the conservation-protection status of natural cover, in this case with a predominance of natural forest cover, and in the levels of intervention to which they are subjected, their history of intervention use, the successional dynamics of the ecosystem components and variables, and the more integrated hydrological response resulting from the close relationship between the microclimatic variables as the vegetation cover evolves according to its phenological processes and stages. It is also important to know and adjust in the best possible way the baseline, with a higher level of instrumentation that can include for example the measurement and monitoring of interception and evaporation variables by the canopy, the flow through the canopy, measuring evapotranspiration, understanding the hydraulic structure of the species and the natural or intervened ecosystem, the stomatal conduction, the sap-flow that help to explain another set of hydrological-forestal processes in this type of research.

·         Therefore, the methodology and the conclusions should be generalized with caution, because sometimes modeling and generalization tend to have a lot of weight even in the absence of much research, which unfortunately in our tropical environment and context such as ours, and even in Latin America, Africa and Asia, in many cases still does not have the importance and sufficient support in terms of economic resources, The main objective of this research is to give greater priority to these aspects and to be able to study climate variability, the effects of climate change itself and, above all, the relationship between vegetation cover and different land uses and their relationship with the flow regime and the hydrological response in a more systemic perspective.

12. C12. Your study mentions the use of tipping bucket rain gauges and level sensors for data collection. It is suggested to provide more details on the calibration and maintenance of these instruments to ensure data accuracy. What specific steps were taken to calibrate and maintain these instruments throughout the study period?

·         It should be noted that the main strategy for monitoring the recording, quality and reliability of the data was supported by visits every 8 days between 1 and 2 days during the first year, and every 15 days in the second and third years to the three experimental microbasins of the Combeima and Cali rivers. During these visits, a careful and detailed examination was made of the data recorded at the time of downloading and uploading the information from the sensors to the computer. Visits that were made simultaneously, at cabinet or office level, to check the data with a greater degree of detail until being convinced that the data that were recorded and that would be processed, indicated levels and references of reliability of the expected data based on some references of this type of information in basins of similar conditions, circumstances and environment instrumented within the Combeima and Cali basins. Also during the first semester and year, these visits were used to do some pre-processing in desk work, in a more thorough and detailed review of the level of information and data that would guarantee a first moment of reliability in the databases and as the development of the research progressed.

·         Sensors were installed to record and monitor rainfall on a one-minute time scale, and to record and track water levels on a five-minute time scale. For rainfall, the use of lithium-based sensors ensured the recording of approximately 50,000 data sets or rainfall events with a record of 5 to 7 years, and for level sensors with a continuous data storage capacity of 4.5 months continuously. However, the flow rates in the weir walls were recorded and followed up by limnimetric rulers, rectangular weirs, and micro-windlass and volumetric gauging on average every 15 days in each micro-basin. Having 4 data for the calculation of the flow in each microbasin.

·         It is recalled and noted that the flow data were adjusted with atmospheric pressure sensors at each flow level monitoring site. These visits were used to perform maintenance due to the deposition of materials in the spillway walls, mainly sediment, gravel, rock blocks and organic vegetable material from palisades, generally transported by the occurrence of maximum floods associated with extreme rainfall events, and in the Tippin bucket rain gauges, the corresponding cleaning and maintenance, with practically no risk of decalibration. Therefore, in the case of level recording for flow, the incidence of cleaning was carefully monitored in the possible deconfiguration of the Of Set level of control and recording reference, with the subsequent check after extreme rainfall events and the corresponding flash floods.

·         Finally, it could be pointed out that one of the strategies and preventive "calibration" work that could have influenced the monitoring of data reliability had to do with the selection of stations that, in perspective of proximity, neighborhood and in part of the methodological context of paired watersheds, should report information and associated data according to their location, orographic gradient, microclimatic conditions and physiographic context or landscape, in terms of proximity, neighborhood and part of the methodological context of the paired watersheds, should report information and related data according to their location, orographic gradient, microclimatic conditions and the context or physiographic landscape itself, trying also to understand the possible effects of levels of intervention of/on land use and the respective patches of vegetation in natural forest.

13. C13. Overall, your study makes a significant contribution to understanding hydrological responses to land use changes in the Colombian Andes. To further strengthen the research, it is suggested to incorporate more field measurements, improve model calibration, and address the potential limitations and uncertainties in the data and modeling approaches. What are the next steps in your research to build on these findings?

·         Completely in agreement. In this sense, we have 5 to 7 years of information on precipitation and flow variables in most of the experimental micro-watersheds, so we will work at another time on the analysis and feasibility of model sensitization tests and complementary evaluation with other variables, to improve the level of understanding of the response associated with the types of natural cover and land use, where it is key to try to evaluate more closely and with a longer term vision (above all with a vision of research process .... .project-process) the conservation dynamics of the ecosystems, the sometimes systematic and progressive intervention of these; it is also important to monitor and evaluate in greater depth the dynamics and interaction of subsurface flows - inter-flows - base flows (minimum flows) and the percolation flows that explain subway flows. Important variables that should be known more are the residence times of water in the soil, in the various layers also related to subsurface and subway conductivities that require greater monitoring and evaluation with specialized instrumentation of water movement in the soil through greater depths of soil profiles associated with the various layers and / or tanks in which the TETIS Model is supported and works.

·         It is also important to prospect and strengthen research on key variables and processes of forest hydrology, instrumenting, measuring and monitoring interception, flow through the canopy, hydraulic structure of forest species and semi-natural vegetation and agroforestry arrangements, stomatal conductance and Sap flow, among others; It is also important to know more closely the rates of mineralization, humification of organic matter, nutrient recycling and the relationship between some of these processes of decomposition of organic matter with the dynamics of water exchange and processing in the soil.

GENERAL COMMENTS

LINE
NUMBERS

SOME SPECIFIC OBSERVATIONS AND RESPONSE

1. Abstract: Authors should differentiate between land use and land cover types. For example, the land uses: natural forest, pasture, and a coffee agroforestry system. Natural forest is land cover. At what scale of the micro watershed level were the responses high – upstream, midstream and downstream. Or demonstrate the sub basin outputs. Present the implications of these values

·         A distinction was made between land use and land cover, and this aspect was applied throughout the manuscript. 

·         The hydrologic response and its behavior at the total area scale was presented and evaluated in each of the six experimental micro-watersheds. As referred to in the title of the manuscript.  

2. Introduction

Page 1, line 36 and 37 – provide citations for these sentences. Generally, this section is well presented, however, the authors should strengthen the contribution of these results to science.

34-37

·         The reviewer's suggestions were duly considered and were increased references cites in this section.

3. Methodology

Since, land use distribution is contentious in the paper, I propose that a land use map should be presented to demonstrate the classification land use types. Otherwise, the methodology clear and replicable.

109

The reviewer's suggestions were duly considered and we added to materials and methods a section with land cover and land use map. Please see respective lines

4. Results

Precipitation behaviour – authors should demonstrate further variations of rainfall and lags. How was drought defined. However, the results are well presented.

·         The months with the lowest precipitation levels or the driest conditions were observed in all micro-basins during the months of December 2015 and February and July 2017. December 2015 was the month with the lowest precipitation levels throughout the entire study period. The lowest rainfall records were observed in August 2016 across all three micro-basins of the Cali river basin, with a slightly higher but still relatively low rainfall regime in this month across the three micro-basins of the Combeima basin. The series revealed a high rainfall regime in all the micro-basins between March and May 2016, with a range of approximately 250 to 340 mm. This was accompanied by a higher rainfall regime in the three micro-basins. In the Combeima basin, rainfall levels fluctuated between 250 and 540 mm, with the highest rainfall regime observed in the MOJ (ASc) micro-basin, reaching approximately 530 mm across the entire study area.

·         Rather than speaking of a drought, it is preferable to speak of seasons or periods of low rainfall and periods with higher rainfall or periods with low and high rainfall, because in reality there were no prolonged periods of more than 3 - 4 months of low and abundant rainfall in the two sub-basins, nor in any of the micro-basins, and rather there was a visible alternation between periods of low and high rainfall throughout the historical series in the two sub-basins and in all the micro-basins.

5. Conclusions

This section is weak and therefore should be improved. Authors should demonstrate further the global justification of these results.

695-740

·         The suggestions were duly considered and the conclusions section has been improved, please see respective manuscript lines.