Assessing the Impact of Groundwater Extraction and Climate Change on a Protected Playa-Lake System in the Southern Iberian Peninsula: La Ratosa Natural Reserve

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

General comments:

The authors quantified the water level variations in a protected playa-lake system based on the numerical model under a changing climate.

Overall, the study is well done and provides useful information.

One thing worth mentioning is the potential use of satellite data for future research in Discussion.

Using satellite data, changes in wetland cover may be captured in this region.

The studies analyzed the wetlands based on satellite data include:

• Hiraga, Y., Kazama, S., Ekkawatpanit, C., & Touge, Y. (2018). Impact of reclamation on the environment of the lower Mekong river basin. Journal of hydrology: Regional studies, 18, 143-155. https://doi.org/10.1016/j.ejrh.2018.06.003
• Zhang, B., Niu, Z., Zhang, D., & Huo, X. (2022). Dynamic changes and driving forces of alpine wetlands on the Qinghai–Tibetan Plateau based on long-term time series satellite data: A case study in the Gansu Maqu wetlands. Remote Sensing, 14(17), 4147. https://doi.org/10.3390/rs14174147

The authors are encouraged to enhance the discussion on the direction of future research based on the studies above or else, which should be helpful for readers.

 

Specific comments:

• Figures

I suggest the authors improve the visualization of the figures, including

Figures 1, 3, and 12 (no location information (lat lon))

Figures 5, 6, 8, 9. and 11 (no labels on axis)

Figures 6 and 8 (no legends in the Figures)

 

 

Author Response

REV 1 General comments:

The authors quantified the water level variations in a protected playa-lake system based on the numerical model under a changing climate.

Overall, the study is well done and provides useful information.

One thing worth mentioning is the potential use of satellite data for future research in Discussion.

Using satellite data, changes in wetland cover may be captured in this region.

The studies analyzed the wetlands based on satellite data include:

• Hiraga, Y., Kazama, S., Ekkawatpanit, C., & Touge, Y. (2018). Impact of reclamation on the environment of the lower Mekong river basin. Journal of hydrology: Regional studies, 18, 143-155. https://doi.org/10.1016/j.ejrh.2018.06.003
• Zhang, B., Niu, Z., Zhang, D., & Huo, X. (2022). Dynamic changes and driving forces of alpine wetlands on the Qinghai–Tibetan Plateau based on long-term time series satellite data: A case study in the Gansu Maqu wetlands. Remote Sensing, 14(17), 4147. https://doi.org/10.3390/rs14174147

The authors are encouraged to enhance the discussion on the direction of future research based on the studies above or else, which should be helpful for readers.

Answer: Thanks. In the new version of the MS, four new references, including the references suggested by reviewer 1 has been included. As a result, the discussion section has been improved (L465-485 in the new version of the MS): “Ecological responses to altered flow regimes have been widely studied in the scientific literature. Robust evidence that links hydrological regime shifts to ecological changes has proven in many papers so the urgency for conservation efforts is therefore imminent. A literature review made to develop quantitative relationships between various kinds of flow alteration and ecological responses can be found in [34]. Ecological responses were categorized by taxonomic groups (macroinvertebrates, fish, riparian vegetation) and response types (abundance, diversity, demographic parameters). A narrative summary confirmed significant and varied ecological impacts from flow alterations. Of the 165 papers reviewed, 92% reported decreased ecological metrics, while 13% reported increases. Not only ecological decline is expected to occur as a consequence of flow alteration due to overexploitation, but also a socioeconomic impact is normally associated to an intense exploitation of aquifers in semiarid climates. Those impacts include agricultural decline, population migration, public health risks, and economic instability [35]. Finally, future research should focus on long-term monitoring using advanced remote sensing technologies to capture temporal changes and predict future trends [36]. Additionally, investigating the exacerbating or mitigating effects of climate change on hydrology and ecology, exploring socio-economic drivers behind reclamation activities, and developing integrated watershed management strategies are crucial. For example, in the Qinghai–Tibetan Plateau [37], these directions provided a comprehensive framework to address the complex challenges faced by these critical ecosystems.”

1. Poff, N. L., & Zimmerman, J. K. (2010). Ecological responses to altered flow regimes: a literature review to inform the science and management of environmental flows. Freshwater biology, 55(1), 194-205.
2. Fessahaye, A. K., Xie, Y., Hu, Y., Dai, G., Zheng, H., & Teng, W. (2025). Groundwater Over-Extraction: Comprehensive Review of Socio-economic Impacts and Pathways to Sustainable Management. European Journal of Theoretical and Applied Sciences, 3(2), 190-211. https://doi.org/10.59324/ejtas.2025.3(2).15
3. Hiraga, Y., Kazama, S., Ekkawatpanit, C., & Touge, Y. (2018). Impact of reclamation on the environment of the lower Mekong river basin. Journal of hydrology: Regional studies, 18, 143-155. https://doi.org/10.1016/j.ejrh.2018.06.003
4. Zhang, B., Niu, Z., Zhang, D., & Huo, X. (2022). Dynamic changes and driving forces of alpine wetlands on the Qinghai–Tibetan Plateau based on long-term time series satellite data: A case study in the Gansu Maqu wetlands. Remote Sensing, 14(17), 4147. https://doi.org/10.3390/rs14174147

 

Specific comments:

• Figures

I suggest the authors improve the visualization of the figures, including

Answer: We acknowledge the reviewer comments about figures, it allowed us to improve the paper.

Figures 1, 3, and 12 (no location information (lat lon))

Answer: We included lat and long in the figures (Coordinates expressed in WGS84, radians).

Figures 5, 6, 8, 9. and 11 (no labels on axis

Answer: We added labels on axis in these figures in the new version of the MS.

Figures 6 and 8 (no legends in the Figures)

Answer: Color lines meaning was in figure captions. We have added the legend to make figures more readable.

In addition, we completely changed Figure 2 in the new version of the MS to avoid the authorship issue detected in the original MS.

Reviewer 2 Report

Comments and Suggestions for Authors

The manuscript is well-structured and makes an important contribution to the understanding of ephemeral playa-lake systems evolution. Through the resoluts it could be relevant to policymakers, conservationists, and environmental scientists. However, by the response to my questions and concerns it could be even more prominent and have a more powerful impact.

1. The authors mention the calibration  ofthe hydrological model, but doesn’t describe it in detail. What exactly were the calibration procedures and which parameters were set in these calibrations?

2. The authors relied on climate data from a meteorological station 15 km away in their modelling, which raises questions about the representativeness of the data for the study area. What limitations does this situation pose and are there any possibilities to alleviate these limitations in the future?

3. The authors are making a comparison with playa lakes in Hungary. Are you aware of other similar situations that would be relevant to compare with in order to show a broader context?

4. The authors mentions about that ecological impacts of changes in hydroperiods, but without supporting it with data or references. The authors should integrate proof to ecological studies that specifically link hydrological regime shifts to observed ecological changes to reinforce the ecological implications and the urgency for conservation.

5. Could the authors provide more detailed information and references regarding the socio-economic impacts of groundwater extraction policies on local communities?

6. In the conclusions section, the authors should explain how their findings specifically inform policy recommendations for mitigating the impacts of groundwater extraction.

7. Can the authors suggest strategies for monitoring ongoing ecological impacts that can be followed beyond the current study?

Author Response

The manuscript is well-structured and makes an important contribution to the understanding of ephemeral playa-lake systems evolution. Through the results it could be relevant to policymakers, conservationists, and environmental scientists. However, by the response to my questions and concerns it could be even more prominent and have a more powerful impact.

1. The authors mention the calibration  of the hydrological model, but doesn’t describe it in detail. What exactly were the calibration procedures and which parameters were set in these calibrations?

Answer: Thanks. In fact, this has been changed in the new version of the MS because is confusing, as it is not exactly a calibration but a correction in the first case and a validation in the second case. In the first case we used the word “calibration” to explain that the estimation of evaporation from ETP values where obtained by multiplying ETP by a constant (1.15). Meaning that, if you obtain a daily value of ETP of 1 mm, there is a current direct evaporation of 1.15 mm/d from an open water surface (i.e., a lake or a reservoir). We changed “calibration” for “estimation” in the new version of the MS. In the second case, we compare actual water level data with data modelled. So this is not a calibration either, but a “validation”. The new paragraph is: “We corrected these values by multiplying by 1.15 to calculate direct evapotranspiration from an open water body as in previous works [23, 14]. The result of the water balance (Hs) is added to the lake water level of the previous day. We validate the model using ordinary least squares method by comparing actual and modelled data.”

2. The authors relied on climate data from a meteorological station 15 km away in their modelling, which raises questions about the representativeness of the data for the study area. What limitations does this situation pose and are there any possibilities to alleviate these limitations in the future?

Answer: We acknowledge the reviewer comment. In the area, the nearest automated meteorological station is the one that we chose. We agree that there could be a difference, as actors such as elevation, vegetation, and urbanization can cause significant local variations in temperature, precipitation, and other climatic variables. But, in this case, the elevation of the meteorological station is very similar to the elevation of the playa-lake.

Sierra de Yeguas (SdY) altitude: 467 m ASL.

Ratosa playa-lake altitude: 448 m ASL.

https://www.juntadeandalucia.es/agriculturaypesca/ifapa/riaweb/web/estacion/29/6

Also we have incorporated data from other nearby meteorological stations within and around the study area to compare the representativeness and accuracy of the precipitation. On the other hand, the water level evolution calculated with the model fits with the precipitation so this is the best way to realize that the precipitation is correct and that it is representative for the modelling of Ratosa’s playa lake water level evolution. Anyway, in order to check out and improve our modelling results we are planning to deploy temporary weather stations and sensors in the shore of Ratosa playa-lake to collect site-specific climate data. In the new version of the MS we have included the altitude of SdY met station.

3. The authors are making a comparison with playa lakes in Hungary. Are you aware of other similar situations that would be relevant to compare with in order to show a broader context?

Answer: Thanks. We are aware, as the reviewer comment, of other similar situations that are indeed relevant. The the most important Andalusian wetland, that is located very near (inf fact it is adjacent to) Ratosa playa-lake is Fuente de Piedra playa-lake. In the new version of the MS we have added a phrase to show the connection of both playa lakes: “This playa lake is sensitive to water input reductions influenced by climate changes, human management, and watershed size changes. It has experienced significant hydrological evolution due to neotectonics and climate variability as well as a reduction in its hydroperiod due to groundwater withdrawal within its watershed [20].”

Pedrera, A., Martos-Rosillo, S., Galindo-Zaldívar, J., Rodríguez-Rodríguez, M., Benavente, J., Martín-Rodríguez, J. F., & Zúñiga-López, M. I. (2016). Unravelling aquifer-wetland interaction using CSAMT and gravity methods: the Mollina-Camorra aquifer and the Fuente de Piedra playa-lake, southern Spain. Journal of Applied Geophysics, 129, 17-27

More information about Fuente de Piedra origin and evolution can be found at:

Rodríguez-Rodríguez, Miguel, Sergio Martos-Rosillo, and Antonio Pedrera. "Hydrogeological behaviour of the Fuente-de-Piedra playa lake and tectonic origin of its basin (Malaga, southern Spain)." Journal of Hydrology 543 (2016): 462-476.

Jiménez-Bonilla, A., Martegani, L., Rodríguez-Rodríguez, M., Gázquez, F., Díaz-Azpíroz, M., Martos, S., ... & Expósito, I. (2024). The role of neotectonics and climate variability in the Pleistocene-to-Holocene hydrological evolution of the Fuente de Piedra playa lake (southern Iberian Peninsula). Hydrology and Earth System Sciences, 28(23), 5311-5329.

4. The authors mentions about that ecological impacts of changes in hydroperiods, but without supporting it with data or references. The authors should integrate proof to ecological studies that specifically link hydrological regime shifts to observed ecological changes to reinforce the ecological implications and the urgency for conservation.

Answer: As the reviewer points out, we have not integrated ecological studies that specifically link hydrological regime shifts to ecological changes. To improve this gap we have consulted several new references and decided to include the one that we found to be better to solve this comment. This report, entitled: “Ecological responses to altered flow regimes: a literature review to inform the science and management of environmental flow” is a comprehensive review of 165 papers that documents strong and variable ecological responses to flow alterations, emphasizing the importance of maintaining ecological flows for biodiversity. This paper provide robust evidence that links hydrological regime shifts to ecological changes, highlighting the urgency for conservation efforts. In the new version of the MS, we added a paragraph integrating this evidence: “Ecological responses to altered flow regimes have been widely studied in the scientific literature. Robust evidence that links hydrological regime shifts to ecological changes has proven in many papers so the urgency for conservation efforts is therefore imminent. A literature review made to develop quantitative relationships between various kinds of flow alteration and ecological responses can be found in [34]. Ecological responses were categorized by taxonomic groups (macroinvertebrates, fish, riparian vegetation) and response types (abundance, diversity, demographic parameters). A narrative summary confirmed significant and varied ecological impacts from flow alterations. Of the 165 papers reviewed, 92% reported decreased ecological metrics, while 13% reported increases.”

New reference added: Poff, N. L., & Zimmerman, J. K. (2010). Ecological responses to altered flow regimes: a literature review to inform the science and management of environmental flows. Freshwater biology, 55(1), 194-205.

5. Could the authors provide more detailed information and references regarding the socio-economic impacts of groundwater extraction policies on local communities?

Answer: Thanks. Sure, in the new version of the MS we have added a new paragraph regarding this impact: “Finally, not only ecological decline is expected to occur as a consequence of flow alteration due to overexploitation, but also a socioeconomic impact is normally associated to a intense exploitation of aquifers in semiarid climates. Those impacts include agricultural decline, population migration, public health risks, and economic instability.”

New reference added: Fessahaye, A. K., Xie, Y., Hu, Y., Dai, G., Zheng, H., & Teng, W. (2025). Groundwater Over-Extraction: Comprehensive Review of Socio-economic Impacts and Pathways to Sustainable Management. European Journal of Theoretical and Applied Sciences, 3(2), 190-211. https://doi.org/10.59324/ejtas.2025.3(2).15

6. In the conclusions section, the authors should explain how their findings specifically inform policy recommendations for mitigating the impacts of groundwater extraction.

Answer: As the reviewer suggests, in the new version of the MS we have added a new paragraph addressing this issue: “Additionally, implementing stricter regulations and continuous monitoring, introducing incentives for water-saving technologies within the watershed and nearby Camorra range, conducting public awareness campaigns, involving local stakeholders in decision-making, investing in advanced monitoring systems, and adopting an integrated water resource management approach would promote sustainable groundwater use and would also address the socio-economic and environmental consequences of over-extraction.”

7. Can the authors suggest strategies for monitoring ongoing ecological impacts that can be followed beyond the current study?

Answer: As a future objective it will be necessary to stablish a monitoring program, to track changes in biodiversity, water quality and habitat conditions.

Reviewer 3 Report

Comments and Suggestions for Authors

The presented work concerns changes in the water balance of lakes in a semi-dry climate. At the outset, it should be noted that in geological history, no-drain depressions are an ephemeral element, with a very short period of functioning. Lakes located in such geomorphological forms disappear very quickly in stratigraphic time as a result of being filled with sediments or changes in the hydrological regime of their supply. In the presented manuscript, the authors present the results of research on the water balance of 2 lakes located in the south of Spain. The research is based, among others, on the results of groundwater level monitoring and mathematical modeling. The authors note that the main cause of the periods of drying out of lakes is climate change and the exploitation of groundwater. In my opinion, these results are credible, especially in the scope presented in Figure 10.

 

The authors plan to publish the article in the Geography MDPI journal. The basic tool for visualizing the concept within geological cartography are maps and cross-sections. The work lacks a hydrogeological cross-section drawn to scale. There is only a model presented in Figure 10. Please include at least one hydrogeological cross-section that will be made to an appropriate scale. Additionally, in the introductory part it would be useful to include a DEM image of the entire studied area. The description of the assumptions made during the modeling studies is also insufficient, below is a list of questions and issues that require supplementation so that the reader of the article is able to better understand the procedure during the studies:

 

1) Lake bottoms undergo the process of clogging very quickly. Fine sediment grains carried by the sediment runoff seal the spaces in the original filter bed that builds the lake bottom. A relatively thin layer is created that limits the free exchange of water between the lake and the aquifer below. How did the authors take this process into account during the modeling work?2) What were the adopted hydrodynamic boundaries of the modeled system? What boundary conditions and initial conditions were adopted for the modeling process?3) What filtration parameters (filtration coefficient was used) and how many geological layers were distinguished during the modeling process?4) What are the legally regulated disposable resources and exploitation resources of groundwater intakes. And what seems most important, what is the approved range of impact of these intakes. The range of impact should take into account the mathematically calculated range of the depression cone induced by each of the wells. Please explain these issues.

 

Please comment on these issues and, ideally, expand the descriptions in the methodology section of the article so that readers can better understand these issues. After additions, I recommend the article for publication in the journal Geography.

Author Response

The presented work concerns changes in the water balance of lakes in a semi-dry climate. At the outset, it should be noted that in geological history, no-drain depressions are an ephemeral element, with a very short period of functioning. Lakes located in such geomorphological forms disappear very quickly in stratigraphic time as a result of being filled with sediments or changes in the hydrological regime of their supply. In the presented manuscript, the authors present the results of research on the water balance of 2 lakes located in the south of Spain. The research is based, among others, on the results of groundwater level monitoring and mathematical modeling. The authors note that the main cause of the periods of drying out of lakes is climate change and the exploitation of groundwater. In my opinion, these results are credible, especially in the scope presented in Figure 10.

 

The authors plan to publish the article in the Geography MDPI journal. The basic tool for visualizing the concept within geological cartography are maps and cross-sections. The work lacks a hydrogeological cross-section drawn to scale. There is only a model presented in Figure 10. Please include at least one hydrogeological cross-section that will be made to an appropriate scale. Additionally, in the introductory part it would be useful to include a DEM image of the entire studied area. The description of the assumptions made during the modeling studies is also insufficient, below is a list of questions and issues that require supplementation so that the reader of the article is able to better understand the procedure during the studies:

 

1) Lake bottoms undergo the process of clogging very quickly. Fine sediment grains carried by the sediment runoff seal the spaces in the original filter bed that builds the lake bottom. A relatively thin layer is created that limits the free exchange of water between the lake and the aquifer below. How did the authors take this process into account during the modeling work?2) What were the adopted hydrodynamic boundaries of the modeled system? What boundary conditions and initial conditions were adopted for the modeling process?3) What filtration parameters (filtration coefficient was used) and how many geological layers were distinguished during the modeling process?4) What are the legally regulated disposable resources and exploitation resources of groundwater intakes. And what seems most important, what is the approved range of impact of these intakes. The range of impact should take into account the mathematically calculated range of the depression cone induced by each of the wells. Please explain these issues.

Answer: Thanks for the questions. We will answer them in the following point by point response:

• In the case of the Ratosa Lake, and other countryside lakes in Andalusia, closed basins are already formed above clayey soils. The permeability of such soils is already very low, enhancing the formation and genesis of playa-lakes that desiccate in summer. A dense vegetation ring made up of phreatophites such as Tamarix sp., Typha sp. and Phragmites sp. is normally ringing the entire shore of the playa-lake, forming a natural defense, and filtering the surface runoff that enters the system. In this sense, clogging of playa-lakes is not a problem in most of the the Andalusian countryside lakes. And it is not a problem in Ratosa playa-lake. The model we used is a unidimensional one that considers the initial water level of the playa-lake and the water inputs and outputs. The water balance is then expressed as water level variations in mm and those variations are computed at a daily scale and added (+) or subtracted (-) to the initial water level to calculate a modelled water level during the calibration period in which we also have the actual evolution of the water level and can compare actual with modelled water level evolution. After the calibration period is checked (validity of the model), we can run the model into future scenarios. Therefore, there is no need to implement clogging process in the model, as requested by the reviewer.
• The boundary conditions and initial conditions that were adopted for the modeling process was the boundary condition of an estimated daily water output by direct evaporation (1,15 * PET_HGreaves evaporation) and imposing a initial condition of a 0,5 m water level (average water level) in the beginning of 2030 for the two scenarios (RCP 4.5 and RCP 8.5).
• No filtration coefficient was used in the model. The playa-lake system is a discharge one, so water outputs considered in the modelling is direct evaporation. This conceptual model has been widely supported by dozens of publications in Andalusian playa-lakes, like, for example:
  830. Rodríguez-Rodríguez, M. (2007). Hydrogeology of ponds, pools, and playa-lakes of southern Spain. Wetlands, 27(4), 819-830. doi:10.1672/0277-5212(2007).
  831. Jiménez-Bonilla, A., Martegani, L., Rodríguez-Rodríguez, M., Gázquez, F., Díaz-Azpíroz, M., Martos, S., Reicherter, K., & Expósito, I. (2024). The role of neotectonics and climate variability in the Pleistocene-to-Holocene hydrological evolution of the Fuente de Piedra playa lake (southern Iberian Peninsula). Hydrology and Earth System Sciences, 28, 5311-5329. doi:10.5194/hess-28-5311-20242.
  832. Rodríguez-Rodríguez, M., Jiménez-Bonilla, A., Díaz-Azpíroz, M., & Gázquez, F. (2024). Decoupling anthropogenic, climatic, and tectonic factors in the hydrology of playa-lakes in a semi-arid, tectonically active region (Betic Orogen, southern Spain). Environmental Earth Sciences, 83, Article 589. doi:10.1007/s12665-024-11894-73.
• The legally regulated exploitation resources of groundwater intakes in Ratosa playa-lake are not yet defined by the administration in charge of the management of such water bodies: (https://www.juntadeandalucia.es/organismos/sostenibilidadymedioambiente.html)

 

Unfortunately, there is no such thing as the approved range of impact of these intakes. Moreover, the depression cone caused by pumping drills in the watershed of Ratosa playa-lake has not yet been mathematically calculated. We completely agree that this task should be necessary to implement and calculate, to better understand the affection of the groundwater pumping in Camorra range to Ratosa playa-lake. The geological complexity of the area and the lack of piezometric data makes it very difficult to properly apply a mathematical model (e.g., v. modflow or model muse) in the watershed of Ratosa – Herriza watershed. But this is a future work that should be done and will be done if the necessary foundation to do it is given by the administration.

Please comment on these issues and, ideally, expand the descriptions in the methodology section of the article so that readers can better understand these issues. After additions, I recommend the article for publication in the journal Geography.

Round 2

Reviewer 2 Report

Comments and Suggestions for Authors

Thank you very much for the precise answers. The authors responded to my requests satisfactorily, I have nothing further to add. Good luck with your further researches!