the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
| 28 Jul 2025
Baseflow in karst regions is significantly higher than the global average and exhibits spatial variability
Abstract. The distinct hydrogeological configurations of karst terrains engender fundamentally divergent baseflow regimes compared with non-karst systems. However, there is still some uncertainty in the understanding of baseflow in global karst regions due to the variability of methods and differences in natural conditions in different regions. In this study, runoff data from 1375 karst basins around the world were summarized, and graphical and digital filtering methods were used to estimate baseflow in global karst regions and to analyze their spatial differences and trends. The results show that the baseflow index of global karst areas is about 78±6.9 %, which is significantly higher than the global average baseflow index (60 %). The baseflow index of karst regions in different climatic zones also differed significantly, in which the average baseflow index of arid karst regions (82 %) was significantly higher than the average baseflow index of subtropical karst regions (77 %). Even within the same climate zone, the base flow index of different regions may also have significant differences, and the difference of some regions is even >10 %. For example, the difference in BFIs between northwestern North America and eastern North America near Hudson Bay, which are both temperate-climate karst zones, is more than 10 %. Vegetation factors reflected in primary productivity have the highest influence on baseflow in karst regions (15 %), while climatic factors (relative humidity, air temperature, etc.) have a lower influence on BFIs in karst regions (less than 5 %). From the time series trend, the global karst baseflow index shows an increasing trend, about 1.5 % from 1960 to 2015. These results help us to further understand karst hydrological processes and the response mechanism of karst hydrology under climate change.
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Notice on discussion status
The requested preprint has a corresponding peer-reviewed final revised paper. You are encouraged to refer to the final revised version.
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Preprint
(1704 KB)
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The requested preprint has a corresponding peer-reviewed final revised paper. You are encouraged to refer to the final revised version.
- Preprint
(1704 KB) - Metadata XML
- BibTeX
- EndNote
- Final revised paper
Journal article(s) based on this preprint
Interactive discussion
Status: closed
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CC1: 'Comment on egusphere-2025-2843', Giacomo Medici, 07 Aug 2025
- CC2: 'Reply on CC1', Qiuwen Zhou, 08 Aug 2025
- AC3: 'Reply on CC1', Qiuwen Zhou, 17 Nov 2025
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RC1: 'Comment on egusphere-2025-2843', Anonymous Referee #1, 25 Sep 2025
The MS “Baseflow in karst regions is significantly higher than the global average and exhibits spatial variability” present a study to investigate the baseflow characteristics and their internal differences in the global karst region and to evaluate the influence of different factors on baseflow. Results found that the BFI in karst regions is generally significantly higher than the global BFI. This MS is very interesting and related to the topic of the HESS.
Some specific comments as follows:
- L27: What is the baseflow index? Please clarify!
- L36: Please provide the full name of the BFIs.
- L45-46: “as a slow recharge component of ...”and “as a hydrological stabiliser”wore both presented. Please rephrase this sentence.
- L60-66: This sentence was too tedious and long. Please improve this sentence.
- L108: For the daily-scale runoff data from 1375 watersheds within the karst region, the datasets for how many years?
- L122: 1412 watersheds? You can directly present the 1375 stations since 37 stations were not used in present study.
- 186-190: Eight methods to calculate the baseflow should be described in detail. Alternatively, you can add a Table to exhibit these eight methods.
- 2: The colors for these four karst regions were to similar. Please improve the color.
- 3-4: Significant difference test should be added.
- 8: Please provide the P value.
Citation: https://doi.org/10.5194/egusphere-2025-2843-RC1 -
CC3: 'Reply on RC1', Qiuwen Zhou, 13 Oct 2025
We sincerely appreciate the reviewer's constructive suggestions. In response, we have provided a point-by-point reply and made corresponding revisions to the manuscript. We are pleased to submit a detailed PDF document containing our complete responses for your consideration.
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AC1: 'Reply on RC1', Qiuwen Zhou, 17 Nov 2025
We extend our sincere gratitude to the reviewers for their valuable comments and suggestions, which have been instrumental in improving the quality of our manuscript and enhancing the rigor of our research. In response to all the feedback, we have carefully addressed each comment point-by-point and systematically compiled the corresponding revisions into a PDF document. This file includes detailed replies to each comment, specific descriptions of the modifications made, and updated figures and tables for the reviewers' reference.
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CC4: 'Comment on egusphere-2025-2843', Yang Lu, 03 Nov 2025
I think this manuscript provides an interesting study into the baseflow in global karst regions. However, there are several issues that merit further clarification and in-depth analysis.
1. The baseflow separation methods seem to generate distinct BFIs and event contrasting trends in certain time periods. How do you tackle the different separation results?
2. In Figure 7, the authors compared BFI in karst regions and the global average. However, the global average is impacted by the coverage ratio of karst regions. Consider replace the global mean with non-karst area mean.
3. Figure 11 shows the factor impact on BFI, but this does not reveal if the impact is positive or negative. Consider including analysis such as SHAP.
Citation: https://doi.org/10.5194/egusphere-2025-2843-CC4 -
CC5: 'Reply on CC4', Qiuwen Zhou, 05 Nov 2025
We sincerely appreciate the reviewer's constructive suggestions. In response, we have provided a point-by-point reply and made corresponding revisions to the manuscript. We are pleased to submit a detailed PDF document containing our complete responses for your consideration.
- AC2: 'Reply on CC4', Qiuwen Zhou, 17 Nov 2025
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CC5: 'Reply on CC4', Qiuwen Zhou, 05 Nov 2025
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EC1: 'Comment on egusphere-2025-2843', Wouter Buytaert, 13 Nov 2025
Thank you to Giacomo Medici and Yang Lu for their constructive comments on the manuscript. In my view, these comments are rigorous enough to serve the purpose of a review. In addition, they are much aligned with those of the anonymous reviewer. As such, I have decided to proceed with making a decision on this manuscript despite having only received one formal review. Copernicus will now close the discussion to enable the next steps.
Citation: https://doi.org/10.5194/egusphere-2025-2843-EC1
Interactive discussion
Status: closed
-
CC1: 'Comment on egusphere-2025-2843', Giacomo Medici, 07 Aug 2025
General comments
Very good hydrological research of large impact. Please, follow my suggestions to improve the final version.
Specific comments
Lines 68-71. Insert new and recent literature for fissures and pipes in karstic dolostones and limestones:
- Medici, G., Munn, J.D., Parker, B.L. 2024. Delineating aquitard characteristics within a Silurian dolostone aquifer using high-density hydraulic head and fracture datasets. Hydrogeology Journal 32(6), 1663-1691.
- Giese, M., Reimann, T., Bailly‐Comte, V., Maréchal, J. C., Sauter, M., Geyer, T. 2018. Turbulent and laminar flow in karst conduits under unsteady flow conditions: Interpretation of pumping tests by discrete conduit‐continuum modeling. Water Resources Research, 54(3), 1918-1933.
Lines 112-113. More detail (e.g., possible ranges and maximum value etc etc) here or in the methodology on KGE and NSE coefficients.
Line 114. The aim is clear, but you need to specify the 3 to 4 specific objectives of your research by using numbers (e.g., i, ii, iii).
Line 193. Here you can insert the necessary methodological details for KGE and NSE coefficients.
Lines 495. Four points in the discussion. Maybe, four objectives to disclose in the introduction?
Figure and tables
Figure 1. Increase graphic resolution or make the figures larger.
Figure 4. Same here, increase graphic resolution or make the figures larger.
Figure 3. Make numbers and letters a bit larger.
Figure 7. I would provide more detail in the introduction on the definitions of the climate. What does it mean “temperate karst”. Semi-arid, humid?
Figure 8. Please, provide more detail on the description of the results for the (i) R2, (ii) NSE and (iii) KGE values which look good. R2 maybe a bit low, but this is ok.
Figure 9. Move Figure 9c below and make the figure larger.
Citation: https://doi.org/10.5194/egusphere-2025-2843-CC1 - CC2: 'Reply on CC1', Qiuwen Zhou, 08 Aug 2025
- AC3: 'Reply on CC1', Qiuwen Zhou, 17 Nov 2025
-
RC1: 'Comment on egusphere-2025-2843', Anonymous Referee #1, 25 Sep 2025
The MS “Baseflow in karst regions is significantly higher than the global average and exhibits spatial variability” present a study to investigate the baseflow characteristics and their internal differences in the global karst region and to evaluate the influence of different factors on baseflow. Results found that the BFI in karst regions is generally significantly higher than the global BFI. This MS is very interesting and related to the topic of the HESS.
Some specific comments as follows:
- L27: What is the baseflow index? Please clarify!
- L36: Please provide the full name of the BFIs.
- L45-46: “as a slow recharge component of ...”and “as a hydrological stabiliser”wore both presented. Please rephrase this sentence.
- L60-66: This sentence was too tedious and long. Please improve this sentence.
- L108: For the daily-scale runoff data from 1375 watersheds within the karst region, the datasets for how many years?
- L122: 1412 watersheds? You can directly present the 1375 stations since 37 stations were not used in present study.
- 186-190: Eight methods to calculate the baseflow should be described in detail. Alternatively, you can add a Table to exhibit these eight methods.
- 2: The colors for these four karst regions were to similar. Please improve the color.
- 3-4: Significant difference test should be added.
- 8: Please provide the P value.
Citation: https://doi.org/10.5194/egusphere-2025-2843-RC1 -
CC3: 'Reply on RC1', Qiuwen Zhou, 13 Oct 2025
We sincerely appreciate the reviewer's constructive suggestions. In response, we have provided a point-by-point reply and made corresponding revisions to the manuscript. We are pleased to submit a detailed PDF document containing our complete responses for your consideration.
-
AC1: 'Reply on RC1', Qiuwen Zhou, 17 Nov 2025
We extend our sincere gratitude to the reviewers for their valuable comments and suggestions, which have been instrumental in improving the quality of our manuscript and enhancing the rigor of our research. In response to all the feedback, we have carefully addressed each comment point-by-point and systematically compiled the corresponding revisions into a PDF document. This file includes detailed replies to each comment, specific descriptions of the modifications made, and updated figures and tables for the reviewers' reference.
-
CC4: 'Comment on egusphere-2025-2843', Yang Lu, 03 Nov 2025
I think this manuscript provides an interesting study into the baseflow in global karst regions. However, there are several issues that merit further clarification and in-depth analysis.
1. The baseflow separation methods seem to generate distinct BFIs and event contrasting trends in certain time periods. How do you tackle the different separation results?
2. In Figure 7, the authors compared BFI in karst regions and the global average. However, the global average is impacted by the coverage ratio of karst regions. Consider replace the global mean with non-karst area mean.
3. Figure 11 shows the factor impact on BFI, but this does not reveal if the impact is positive or negative. Consider including analysis such as SHAP.
Citation: https://doi.org/10.5194/egusphere-2025-2843-CC4 -
CC5: 'Reply on CC4', Qiuwen Zhou, 05 Nov 2025
We sincerely appreciate the reviewer's constructive suggestions. In response, we have provided a point-by-point reply and made corresponding revisions to the manuscript. We are pleased to submit a detailed PDF document containing our complete responses for your consideration.
- AC2: 'Reply on CC4', Qiuwen Zhou, 17 Nov 2025
-
CC5: 'Reply on CC4', Qiuwen Zhou, 05 Nov 2025
-
EC1: 'Comment on egusphere-2025-2843', Wouter Buytaert, 13 Nov 2025
Thank you to Giacomo Medici and Yang Lu for their constructive comments on the manuscript. In my view, these comments are rigorous enough to serve the purpose of a review. In addition, they are much aligned with those of the anonymous reviewer. As such, I have decided to proceed with making a decision on this manuscript despite having only received one formal review. Copernicus will now close the discussion to enable the next steps.
Citation: https://doi.org/10.5194/egusphere-2025-2843-EC1
Peer review completion
Journal article(s) based on this preprint
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- 1
Ze Yuan
Qiuwen Zhou
Yuan Li
Yuluan Zhao
Shengtian Yang
The requested preprint has a corresponding peer-reviewed final revised paper. You are encouraged to refer to the final revised version.
- Preprint
(1704 KB) - Metadata XML
General comments
Very good hydrological research of large impact. Please, follow my suggestions to improve the final version.
Specific comments
Lines 68-71. Insert new and recent literature for fissures and pipes in karstic dolostones and limestones:
- Medici, G., Munn, J.D., Parker, B.L. 2024. Delineating aquitard characteristics within a Silurian dolostone aquifer using high-density hydraulic head and fracture datasets. Hydrogeology Journal 32(6), 1663-1691.
- Giese, M., Reimann, T., Bailly‐Comte, V., Maréchal, J. C., Sauter, M., Geyer, T. 2018. Turbulent and laminar flow in karst conduits under unsteady flow conditions: Interpretation of pumping tests by discrete conduit‐continuum modeling. Water Resources Research, 54(3), 1918-1933.
Lines 112-113. More detail (e.g., possible ranges and maximum value etc etc) here or in the methodology on KGE and NSE coefficients.
Line 114. The aim is clear, but you need to specify the 3 to 4 specific objectives of your research by using numbers (e.g., i, ii, iii).
Line 193. Here you can insert the necessary methodological details for KGE and NSE coefficients.
Lines 495. Four points in the discussion. Maybe, four objectives to disclose in the introduction?
Figure and tables
Figure 1. Increase graphic resolution or make the figures larger.
Figure 4. Same here, increase graphic resolution or make the figures larger.
Figure 3. Make numbers and letters a bit larger.
Figure 7. I would provide more detail in the introduction on the definitions of the climate. What does it mean “temperate karst”. Semi-arid, humid?
Figure 8. Please, provide more detail on the description of the results for the (i) R2, (ii) NSE and (iii) KGE values which look good. R2 maybe a bit low, but this is ok.
Figure 9. Move Figure 9c below and make the figure larger.