The Impact of Climate Change on Evapotranspiration and Flow in a Major Basin in Northern Mexico

Round 1

Reviewer 1 Report

Comments for author File: Comments.pdf

Author Response

Reviewer 1: In material and method add a paragraph on the climate of the area containing a description of e.g. rainfall seasonality, temperature and precipitation trends, ecc.. It should be clearly stated that if only one weather station is available, it should be indicated where it is located (location and altitude It should be indicated that in order to have more meaningful source data, perhaps a high-altitude monitoring station would be needed. In short, the significance of all the data used in the forecast model should be clarified. A description of the geological and hydrogeological structure of the basin is lacking; for example, it would be useful to know the type of aquifer, its depth, piezometry (if any) and the relationship of the water table (draining or feeding) with the analysed watercourse. Knowing the type of soil and substrate in geological and hydrogeological terms (e.g. hydraulic conductivity) can also be of support in assessing effective infiltration, for example. In almost all figures, it is necessary to enlarge the text. In particular the text of the legend in fig.1, the names of the axes, the numbers and the equations of the graphs in figures 4,6,7,8 and 9. When using simulation models, all variables, values associated with the variables, and assumptions and simplifications must be described and justified. In the Matherials and Methods, it is necessary to devote a few lines to describing the different SSPs 126, 245, 370 and 585, highlighting their main features and differences. The explanation of the GR2M model should also be revised and implemented (Lines 130-142).

Authors: Information on precipitation, temperature and runoff trends was included. Aquifer information was included, such as hydrogeology and hydraulic parameters for aquifer characterization. The axis of the figures suggested by the reviewer were edited. More information on the SSPs was included to differentiate them.

Reviewer 1: Line 104 “In all stages of the model, Ri has a reference parameter of 60 mm.” Please, explain why you chose 60 mm, does it come from any studies? Did you do any processing to obtain this value?

Authors: The 60 mm corresponds to a reference parameter of maximum reservoir capacity, therefore, the 60 mm are model input data.

Reviewer 1: Line 126 – Normally the unit of flow or flow rate (Q) is volume/time (e.g m3/s), please clarify how mm is obtained.

Authors: We work with mm because the input variables of the model are mm (evapotranspiration and precipitation) as GR2M is based on reservoir sheets, the runoff result is in mm. This methodology is presented in the GR2M model and hydro-environmental variables section.

Reviewer 1: Lines 130-142 The different steps and variables that make up the model must be explained by introducing all the explanations of the symbols shown in Fig. 2. For example in the sentence: “If the reservoir reaches the S1 level (mm), it loses part through evaporation (Stage 3), until it reaches the S2 level (mm) and becomes part of the soil moisture P2 (mm), and is then transferred to the routing reservoir by percolation through the soil (Stage 4). Should be specified which reservoir, the symbol E should be added to evaporation, what P2 is, etc. should be explained

Authors: The steps in the GR2M model and hydro-environmental variables section were defined, and the meaning of the letters was clarified.

Reviewer 1: Line 156 – Please revise the formula iQobs or Qi obs ?

Authors: Corrected the formula to Qobs

Reviewer 1: Line 158 – Please revise the formula iQobs or Qi obs ?

Authors: Corrected the formula to Qobs

Reviewer 1: Line 160 _ Please add definition of i and of iabs

Authors: Corrected and left only as abs.

Reviewer 1: Lines 160-161- Please check the unit of measurement adopted for the flow. Are you sure they are mm? Justify the choice

Authors: We work with mm because the input variables of the model are mm (evapotranspiration and precipitation) as GR2M is based on reservoir sheets, the runoff result is in mm. This methodology is presented in the GR2M model and hydro-environmental variables section.

Reviewer 1: Line 169 – Please decide whether to use Tmed or Tmean in the formulas, for the average temperature, and use the same symbolism. I suggest using Tmean, since you have already defined it before

Authors: Consideration was given to what was proposed by the reviewer Tmean

Reviewer 1: Line 195- Always add the level of significance adopted in the Pettitt tests.

Authors: Significance level was included for Pettitt's test (p < 0.05).

Reviewer 1: Line 200_ Please correct the formula: Dij = −1 if (xi−xj) > 0 in Dij = −1 if (xi−xj) < 0

Authors: The formula has been corrected

Reviewer 1: Line 202- Specify that  in the level of significance adopted in the Mann Kendall tests.

Authors: The significance level of the Man Kendall test was included (p < 0.05).

Reviewer 1: Line 203  please add the term “monotonic” before linear trend

Authors: The term suggested by the author was included.

Reviewer 1: Line 208 – the formula is not complete. Please correct it

Authors: The formula has been completed

Reviewer 1: Lines 242-244 - Unclear, perhaps removing the phrase in 'in terms of precipitation' makes it clear

Authors: Reviewer's suggestion considered

Reviewer 1: Lines 244-248- Please check the flow measuring unit

Authors: The methodology presents these GR2M model units.

Reviewer 1: Lines 264-296 - If possible, add a time diagram of the temperature of the area under investigation with an indication of the increasing trend.

Authors: No diagram was included, because there are 9 figures, but the climatic information is included in the section on materials and methods.

Reviewer 1: Line 249 - Check the axis names of the scatterplot (b). I think they should be reversed, as the rainfall reported in the diagram (a) reaches a maximum of 250 mm while the flow rates exceed 600 m3/s. Check the unit of measurement of the flow rates

Authors: Figure corrected.

Reviewer 1: Lines 321- Specify what those numbers are. Are they the slopes? By how many mm/year does evapotranspiration grow? Or state how many mm evaporation grows in 10, 20, 50 years.

Authors: corresponds to slope.

Reviewer 1: Lines 323-328 - Please reduce the number of decimals (I suggest not putting more than one or two decimal digits).

Authors: Decimals were reduced

Reviewer 1: Line 335-337 – In the figures put the same scale as the y-axis.

Authors: The axis were placed in the same scale

Reviewer 1: Line 341-.353- Check and correct the flow measuring unit

Authors: The methodology for using mm was followed.

Reviewer 1: Line 373 – In the figures put the same scale as the y-axis. Add in the caption, the explanation of figures a, b, c, d.

Authors: The scale was homogenized in the figures and the following were described

Reviewer 1: Line 400 – I propose to rewrite the sentence:

“However, significant seasonal increases are found between scenarios. These variabilities allow the observation of changes in the seasonal cycle of flows (Figure 8), mainly caused

by changes in the precipitation regime (frequency and intensity), which in turn can affect water resources [58].”. It could be rewritten like this:

However, in all scenarios, there are significant increases and changes in the seasonal flow cycle (Figure 8), mainly due to changes in the rainfall regime (frequency and intensity) [58].

Authors: The reviewer's suggestion was considered and the paragraph was modified.

Reviewer 1: Lines 408-409 Please specify the variability of what

Authors: It was specified what the sentence refers to in order to provide coherence

Reviewer 1: Lines 414-417 Please rewrite the sentence, it is difficult to understand.

Authors: The paragraph was rewritten

Reviewer 1: Lines 414-417 Please rewrite the sentence, it is difficult to understand.

Authors: This information was included in materials and methods

Author Response File: Author Response.docx

Reviewer 2 Report

Comments

The peer-reviewed paper presents the results of an assessment of runoff changes and water resources in northern Mexico. The implementation of this research goal was based on the application of the GR2M model to simulate the flows in the 21st century. This study was carried out on the basis of climate change simulations for 4 different socio-economic scenarios realized in the CMIP6 project.

In the first step, the GR2M model was used to simulate the runoff in the period 1970-2006. The obtained results and their comparison with the measurements made it possible to calibrate the model for the geographical conditions of the studied area and to evaluate the errors obtained from the model.

In the next step, a calibrated GR2M model for Sierra Madre Occidental conditions was used to assess 21st century runoff changes for 4 Shared Socioeconomic Pathways scenarios. In the opinion of the reviewer, it should be emphasized that the results were discussed. The authors of the article, presenting the obtained results, pay attention to the possible effects of the forecasted changes on water resources in the studied area. The obtained results are also compared with those obtained in other studies.

Suggestions

L. 83-86 – I suggest editing the information about the research objectives of the work. The goals in the abstract are different than in this passage.

L. 85 – I suggest you improve the description of SSP types. E.g. SSP1-2.6 (the suggestion applies to the entire article)

L. 97 – monthly mean values?

L. 187 – Tmed - monthly mean temperature?

Author Response

Reviewer 2: The peer-reviewed paper presents the results of an assessment of runoff changes and water resources in northern Mexico. The implementation of this research goal was based on the application of the GR2M model to simulate the flows in the 21st century. This study was carried out on the basis of climate change simulations for 4 different socio-economic scenarios realized in the CMIP6 project.

In the first step, the GR2M model was used to simulate the runoff in the period 1970-2006. The obtained results and their comparison with the measurements made it possible to calibrate the model for the geographical conditions of the studied area and to evaluate the errors obtained from the model.

In the next step, a calibrated GR2M model for Sierra Madre Occidental conditions was used to assess 21st century runoff changes for 4 Shared Socioeconomic Pathways scenarios. In the opinion of the reviewer, it should be emphasized that the results were discussed. The authors of the article, presenting the obtained results, pay attention to the possible effects of the forecasted changes on water resources in the studied area. The obtained results are also compared with those obtained in other studies.

Suggestions

Reviewer 2: L. 83-86 – I suggest editing the information about the research objectives of the work. The goals in the abstract are different than in this passage.

Authors: The objective was rewritten to coincide with the abstract and introduction

Line 85 – I suggest you improve the description of SSP types. E.g. SSP1-2.6 (the suggestion applies to the entire article)

Authors: Information describing the SSPs and by type is included in the materials and methods section

Line 97 – monthly mean values?

Authors: Monthly average maximum and minimum temperatures were included to correctly describe the climate

Line 187 – Tmed - monthly mean temperature?

Authors: Was rewrited as suggested by the reviewer

Author Response File: Author Response.docx

Reviewer 3 Report

Please find my comments attached.

Comments for author File: Comments.pdf

Author Response

Reviewer 3: The North American Monsoon is largely driven by topography. Does CNRM

represent topography to a sufficient degree such that the monsoon is realistic?

An analysis of the North American Monsoon in the historical period compared

with observations would prove this.

Authors: The analysis proposed by the reviewer may provide information to validate the use of the CNRM model in Mexico, because the main doubt is the representation of variability in the Monsoon, however, this analysis is not part of the objectives of this study. For the selection of the CNRM model, references and previous studies that have used this model for Mexico were consulted, such as Reyes-Bonilla et al. 2021 and Almazroi et al., 2021, which used the model proposed in this study to simulate climate variability in Mexico.

Reyes Bonilla, H., Morzaria Luna, H.N., Petatán Ramírez, D., Vázquez Vera, L., Cruz Piñón, G., Dorantes, J.M., Torres Origel. J.F., Rojas Montiel, B., Torres Rodríguez, L.M., Cisneros Mata, M.A., Pérez Muñoz, A., Lara Mendoza, R.E., López Téllez, N.A., Díaz Uribe, J.G., Ingle de la Mora, G., Jiménez Quiroz, M.C., Martínez Moreno. R., Castro Garibay, H. y Calderón Alvarado, J.M. (2021). Evaluaciones de vulnerabilidad de las comunidades costeras y de cambio en la disponibilidad de los recursos pesqueros y acuícolas de la costa de México. EDF de México y UABCS. La Paz Baja California Sur, México.

Almazroui, M., Islam, M.N., Saeed, F. et al. Projected Changes in Temperature and Precipitation Over the United States, Central America, and the Caribbean in CMIP6 GCMs. Earth Syst Environ 5, 1–24 (2021). https://doi.org/10.1007/s41748-021-00199-5

Reviewer 3: One reason the highest SSP is frequently used in these types of studies is that it

presents a higher signal-to-noise ratio. Is it possible to tell if the changes in the

lower magnitude SSPs are significant? Especially in cases where the signal from

the lower emissions scenario disagrees with the signal from the stronger forcing.

Authors: The objective of the study was to compare the impact of climate change on evapotranspiration and runoff for 4 different scenarios, analyzing their expected behavior with scenarios 126, 245, 370 and 585. Changes in scenarios 126 and 245 were analyzed through trend and value before and after the break point with the Mann Kendall and Pettitt tests. The behavior between scenarios is similar, but with the differences that lie according to each scenario in the face of socioeconomic, environmental, etc. actions.

Reviewer 3: In addition to Major Concern 1, how certain are the authors with the evolution of this single realization? In this region GCMs differ considerably, even within a

single GCM suite.

Authors: The use of the CNRM was not specifically addressed, but according to the literature, from the different global circulation models, it represents the variability of northern Mexico, and is also used for modeling the distribution of species for Mexico and projecting variability (Martínez-Sifuentes et al., 2020; Manzanilla-Quiñones et al., 2021).

Martínez-Sifuentes AR, VillanuevaDíaz J, Manzanilla-Quiñones U, BecerraLópez JL, Hernández-Herrera JA, EstradaÁvalos J, Velázquez-Pérez AH (2020). Spatial modeling of the ecological niche of Pinus greggii Engelm. (Pinaceae): a species conservation proposal in Mexico under climatic change scenarios. iForest 13: 426-434. – doi: 10.3832/ifor3491-013 [online 2020-09-16]

Manzanilla-Quiñones U, Pozo-Montuy G, Delgado-Valerio P, Martínez-Sifuentes AR, Aguirre Calderón O A (2021) Escenarios climáticos (CMIP-5) para la Reserva de la Biosfera Pantanos de Centla, Tabasco, México. Ecosistemas y Recursos Agropecuarios Núm. Esp. I: e2588. DOI: 10.19136/era.a8nI.2588

Reviewer 3

Minor comments

General:

Reviewer 3: What realization of CNRM-CM6-1 is used for this experiment, please specify.

Autores: Se descargó de la plataforma WorldClima 2.1 la información climática de temperatura mínima, máxima y precipitación del modelo CNRM-CM6-1 en formato GeoTIFF, dicha información mediante GIS se analizó para obtener la información climática del modelo

Reviewer 3: Line 126 and elsewhere: Suggest changing ETP to PET to be in line with convention, or subscripting the P as in ETP.

Authors: ETP was changed to PET as suggested by the reviewer.

Reviewer 3: Lines 154–158: suggest using subscripts to avoid confusion.

Authors: The formulas were corrected and it was made clear

Reviewer 3: Lines 197–198: “...of Ut, where T is defined by the following equation…”. Th

is line and the following equation is confusing. Please correct for clarity.

Authors: Improved writing

Reviewer 3: Line 210 here and elsewhere: suggest suggest change UMK to UMK

Authors: Modified according to reviewer's suggestion.

Reviewer 3: Line 228: suggest “1–7” instead of “1, 2, 3, 4, 5, 6,and 7”

Authors: The modification was made as suggested by the reviewer.

Reviewer 3: Line 239: suggest defining “pedregosity”.

Authors: The definition of pedregosity was included.

Reviewer 3: Line 393: suggest “…has 38 035 thousand users…”

Authors: The modification was made as suggested by the reviewer.

Reviewer 3: Figure 6: Suggest changing the x-axis in Figure 6a.

Authors: X-axis change was made

Reviewer 3: Figure 7: Why is there a large multi-decadal cycle in potential vapotranspiration? Same question in Figure 8 for streamflow.

Authors: Due to the information provided by the WorldClim CNRM model provides data for the 2030, 2050, 2070 and 2090 horizons, that is why they are represented graphically as multidecadal cycles.

Reviewer 3: Figure 8: Define every part of the figure in the caption. Please fix the x-axis.

Authors: The information in Figure 8 was defined for better understanding.

Author Response File: Author Response.docx

Reviewer 4 Report

Comments:

This manuscript evaluates the impact of future climate change (2021-2100) on the hydrology (evapotranspiration and flows) of the Sardinas River Basin, northern Mexico. The highlight is on the changes in evapotranspiration and flow derived from the GR2M model under the four scenarios. It is of great significance to explore impact of climate on the hydrology, do so can facilitate the optimal allocation of water regulation and water resources conservation measures. Thus, the topic is indeed of scientific interest and importance. However, the method description in this paper is not clear and complete, the content and analysis are lack of depth, and there are many mistakes in the presentation. Therefore, I recommend major revision can I recommend it. Following are the detailed comments:

1)        In Abstract, line 13, maybe you should emphasize the importance of research. In lines 16 to 18, the description of “The Rural Genius Model” and methods to determine trends are too simple short sentences. It’s the same with lines 19 to 21, which are too simple and short sentences to describe your research results without analysis. Overall, the authors should understand the meaning of abstract is gathering the significant points in your manuscript/paper by organizing the language logically.

2)      In Introduction, I know the authors want to describe the research context well, but there are too many subsections for an introduction.

3)      In line 29, there is a grammatical problem with this sentence, “Faced with…, the impact…”. If “Faced with” is used, the subject cannot be “the impact”.

4)        In line 64, “This hydrological model has been widely used by several authors with very satisfactory results.”, the authors are supposed to give more evidence, such as a comparison of different models or concrete examples within the Rural Genius model. What's more, the wording of scientific research papers should be rigorous, so “very’ here needs to be considered again. It's the same with line 287.

5)        In lines 83 to 86, the research method should be added. This subsection seems much too succinct, which is not conducive for readers to understand what you did.

6)        In 1ine 144 and 281, where are the other semi-brackets?

7)        In sections “2.3 Pettitt's test” and “2.4 Mann-Kendall test”, data processing methods introduced are vague, and critical methods used in MS need to be described in detail to some extent rather than given math formulas.

8)        In all formulas, what's the meaning of “i”?

9)        In line 245, “coincided with the North American Monsoon System” needs to be proven or provide more literature citations. The literature citations were insufficient, and it seems only one citation (2013) was from nine years ago.

10)     In lines 264 to 269, the reasons for the rising ETP can be discussed in detail instead of a simple description.

11)     In lines 266 to 269, there should be a comma before “such as.” Also, “for example” can be used here. It will be: “Different ocean-atmosphere phenomena impact this region. For example, La Niña causes periods of severe droughts due to low precipitation and high temperatures, resulting in changes in the parameters of the hydrological cycle, such as the ETP.”

12)     In Figure 2 and Figure 4, the formula on the right side of Figure 2 is blurred. The font in Figure 4 is too small, and the image is blurred. Several Figures have the same blurring issues.

13)     In Figure 6, the simulated data may be drawn with a red dotted line, and now it is not clear. The vertical coordinate of the left figure may change color to match the legend color.

14)     In Figure 9, what’s the meaning of red lines?

15)     In line 310, please modify the description: “… according to the projections [43]” as “… according to projections of Intergovernmental Panel on Climate Change [43]”.

16)     In lines 360 to 369, where the authors described and analyzed Figure 9, the description here is too simplistic. It only explained the histogram part of Figure 9. The red line was not quantified or explained, nor did it analyze the causes of different flows under different SSPs. If you set different scenarios, a phenomenon explanation is a must here.

17)     In line 421, there is one more vertical line.

18)     In Conclusion, please don't repeat results, you should have extensions and rewrites. In addition, it is also necessary to emphasize that contribution corresponds to introduction.

19)     Some related articles may be appropriate for referring:

Fubo Zhao, Yiping Wu, Yingying Yao, et al., Predicting the climate change impacts on water-carbon coupling cycles for a loess hilly-gully watershed, Journal of Hydrology, 2020, 581: 1-11.

Fubo Zhao et al., Toward Sustainable Revegetation in the Loess Plateau Using Coupled Water and Carbon Management, Engineering, 2022

Author Response

Reviewer 4: In Abstract, line 13, maybe you should emphasize the importance of research. In lines 16 to 18, the description of “The Rural Genius Model” and methods to determine trends are too simple short sentences. It’s the same with lines 19 to 21, which are too simple and short sentences to describe your research results without analysis. Overall, the authors should understand the meaning of abstract is gathering the significant points in your manuscript/paper by organizing the language logically.

Authors: The abstract was improved as suggested by the reviewer.

Reviewer 4: In line 29, there is a grammatical problem with this sentence, “Faced with…, the impact…”. If “Faced with” is used, the subject cannot be “the impact”.

Authors: The problem was corrected

Reviewer 4: In line 64, “This hydrological model has been widely used by several authors with very satisfactory results.”, the authors are supposed to give more evidence, such as a comparison of different models or concrete examples within the Rural Genius model. What's more, the wording of scientific research papers should be rigorous, so “very’ here needs to be considered again. It's the same with line 287.

Authors: A paragraph was included with studies where the GR2M was better than other models; the word "very" was eliminated to avoid overestimating the efficiency of all models.

Segura-Méndez, FJ (2017). Análisis comparativo de modelos agregados de balance hídrico en la España peninsular y su sensibilidad a la incertidumbre climática. Programa de doctorado en urbanismo. Universidad Católica de Murcia.

Gallo-Llumigusin KE & Iza-Jiménez BA (2018). Modelamiento con SWAT y GR2M para la subcuenca del río Guayllabamba. Ingeniería en medio ambiente. Universidad Técnica de Cotopaxi.

Reviewer 4: In lines 83 to 86, the research method should be added. This subsection seems much too succinct, which is not conducive for readers to understand what you did.

Authors: The section was rewritten to improve clarity.

Reviewer 4: In 1ine 144 and 281, where are the other semi-brackets?

Authors: The lack or absence of semi-brackets was analyzed and the observation was addressed.

Reviewer 4: In sections “2.3 Pettitt's test” and “2.4 Mann-Kendall test”, data processing methods introduced are vague, and critical methods used in MS need to be described in detail to some extent rather than given math formulas

Authors: It was only decided to include the description and mathematical formulas because it is not the essential part of the PET evaluation analysis and flow simulation, so emphasis was given to the development and description of the GR2M model.

Reviewer 4: In all formulas, what's the meaning of “i”?

Authors: The subscript "i" was eliminated in the mathematical formulas of the evaluation methods.

Reviewer 4:    In line 245, “coincided with the North American Monsoon System” needs to be proven or provide more literature citations. The literature citations were insufficient, and it seems only one citation (2013) was from nine years ago.

Authors: References were included to corroborate this fact.

Liu T, Li J. Wang Q, Zhao S (2020). Influence of the autumm SST in the southern pacific ocean on Winter precipitation in the North American Monsoon Region. Atmosphere. 11(8) https://doi.org/10.3390/atmos11080844

Pascale S, Carvalho L, Adams D, Castro Ch, Cavalcanti I (2019) Current and future variations of the Monsoon of the Americas in warming climate. 5: 125-144. https://doi.org/10.1007/s40641-019-00135-w

Reviewer 4: In lines 264 to 269, the reasons for the rising ETP can be discussed in detail instead of a simple description.

Autore: The discussion of the increase in ETP was enhanced.

Sun, S., Bi, Z., Zhou, S., Wang, H., Li, Q., Liu, Y., Wang, G., et al., 2021. Spatiotemporal shifts in key hydrological variables and dominant factors over China. Hydrol. Process. 35, e14319. https://doi.org/10.1002/hyp.14319

Zhang, S., Yang, Y., McVicar, T.R., Yang, D., 2018. An analytical solution for the impact of vegetation changes on hydrological partitioning within the Budyko framework. Water Resour. Res. 54, 519–537. https://doi.org/10.1002/2017WR022028.

Zhang, D., Liu, X., Zhang, L., Zhang, Q., Gan, R., Li, X., 2020. Attribution of evapotranspiration changes in humid regions of China from 1982 to 2016. J. Geophys. Res. Atmos. 125, e2020JD032404 https://doi.org/10.1029/2020JD032404

Cavalcante, R.B.L., Pontes, P.R.M., Souza, P.W.M., de Souza, E.B., 2019. Opposite effects of climate and land use changes on the annual water balance in the Amazon arc of deforestation. Water Resour. Res. 55, 3092–3106. https://doi.org/10.1029/2019WR025083

Xie, S., Mo, X., Hu, S., Liu, S., 2020. Contributions of climate change, elevated atmospheric CO2 and human activities to ET and GPP trends in the Three-North Region of China. Agric. For. Meteorol. 295, 108183 https://doi.org/10.1016/j.agrformet.2020.108183

Reviewer 4: lines 266 to 269, there should be a comma before “such as.” Also, “for example” can be used here. It will be: “Different ocean-atmosphere phenomena impact this region. For example, La Niña causes periods of severe droughts due to low precipitation and high temperatures, resulting in changes in the parameters of the hydrological cycle, such as the ETP.”

Authors. It was modified according to the reviewer's proposal.

Reviewer 4: In Figure 2 and Figure 4, the formula on the right side of Figure 2 is blurred. The font in Figure 4 is too small, and the image is blurred. Several Figures have the same blurring issues.

Authors: Figure resolution was improved

Reviewer 4: In Figure 6, the simulated data may be drawn with a red dotted line, and now it is not clear. The vertical coordinate of the left figure may change color to match the legend color

Authors: Figure 6 was edited according to the reviewer's suggestion.

Reviewer 4: In Figure 9, what’s the meaning of red lines?

Authors: The red line is the trend, the reference was placed in the figure caption.

Reviewer 4: In line 310, please modify the description: “… according to the projections [43]” as “… according to projections of Intergovernmental Panel on Climate Change [43]”.

Authors: The wording was modified as suggested by the reviewer.

Reviewer 4: In lines 360 to 369, where the authors described and analyzed Figure 9, the description here is too simplistic. It only explained the histogram part of Figure 9. The red line was not quantified or explained, nor did it analyze the causes of different flows under different SSPs. If you set different scenarios, a phenomenon explanation is a must here.

Authors: The discussion was expanded as suggested by the reviewer.

Yao, Y.; Qu, W.; Lu, J.; Cheng, H.; Pang, Z.; Lei, T.; Tan, Y. Responses of Hydrological Processes under Different Shared Socioeconomic Pathway Scenarios in the Huaihe River Basin, China. Water 2021, 13, 1053. https://doi.org/10.3390/w13081053

Reviewer 4:  In line 421, there is one more vertical line.

Authors: The line is for the page break.

Reviewer 4: In Conclusion, please don't repeat results, you should have extensions and rewrites. In addition, it is also necessary to emphasize that contribution corresponds to introduction.

Autores: The conclusions was improved

Author Response File: Author Response.docx

Round 2

Reviewer 1 Report

The work has improved on the first version and can be published in this form.

Author Response

Thanks for the revisions that improved the quality of the manuscript

Reviewer 3 Report

Please see my comments attached.

Comments for author File: Comments.pdf

Author Response

REVIEWER 3: For this comment, the point is that the objective/method of the study is being questioned. While the lower emissions scenarios are useful for determining temperature responses in a global mean sense, they are less useful for doing regional analysis. This is because emissions do not affect the hydroclimate directly, but rather they impact the temperature, and then the temperature drives the thermodynamic and dynamic responses of hydroclimate. The issue with the lower emission scenarios, in this case, is that they do not elicit a strong enough temperatura response to drive hydroclimate change that is detectable beyond the internal variability. This is especially the case on regional scales, because dynamics become more important. Precipitation as reported in Table 2 shows clear signs of internal variability dilution. For Example, See Table 2:

First, look across the 2030 line. Before the emissions scenarios have sufficient time to affect the climate, there is a small signal-to-noise ratio, as evidenced by the highest changes in both the smallest and largest emissions scenarios, with a minimum in the middle (probably all internal variability). Then look at the at SSP126. This emissions scenario is unlikely to have changed the temperature sufficiently to produce a significant signal-to-noise ratio, even by the end of the century. In Table2, SSP126, shows the precipitation signal decreasing by almost 40% between 2050 and 2070, then increasing by about the same amount by 2090—abrupt changes like this are evidence that this scenario is probably depicting internal variability.

How can this be addressed? Usually in these types of studies many models (or many realizations of a single model) are used to contend with the issue of internal variability. Furthermore, those models need to be downscaled (either statistically or dynamically) to account for topographical influences etc. Downscaling is more important when the area that is being studied is a small fraction of the 2.5º x 2.5º GCM grid, as it is in this study. It is posible that the authors could just remove SSP126, but even with SSP585 at the end of the century can be difficult to determine signal from noise in certain regions. While I believe the other aspects of the paper are satisfactory, this component needs some more thought.

Authors: We consider the reviewer's comment is a good one, where the signal-to-noise ratio effect is diluted in some scenarios and therefore, no significant effect is observed, where topographic conditions have an important influence.

The authors would like to mention that since the study was developed in 2020, new GCMs at a finer spatial scale were not yet available, therefore, the most detailed was at 2.5° x 2.5°, but we consider it a good approximation to see the effect of variability. Commonly other studies only compare two horizons and two SSP or RCP scenarios, but in this study we wanted to present each of the available horizons and SSP scenarios.

If we eliminate the SSP 126 and 585 scenarios, we consider that the essence of what we want to capture in the study, a monitoring of the allowable variability in this important water producing basin in northern Mexico, is lost.

What follows in the conclusions section is to expose what the reviewer suggests, to expose the limitations of working with only one model and with all the scenarios at the 2.5° x 2.5° scale, to serve as an explanatory note for future work related to future climate variability with these characteristics of the models.

Author Response File: Author Response.docx

Reviewer 4 Report

Thanks for the authors' revision.

Author Response

Thanks for the revisions that improved the quality of the manuscript