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

Academic Editor: Luca Salvati Received: 13 March 2025 Revised: 23 April 2025 Accepted: 28 April 2025 Published: 8 May 2025 Citation: Rodríguez-Rodríguez, M.; Halmos, L.; Jiménez-Bonilla, A.; Díaz-Azpiroz, M.; Gázquez, F.; Delgado, J.; Fernández-Ayuso, A.; Expósito, I.; Martos-Rosillo, S.; Yanes, J.L. Assessing the Impact of Groundwater Extraction and Climate Change on a Protected Playa-Lake System in the Southern Iberian Peninsula: La Ratosa Natural Reserve. Geographies 2025,5, 21. https://doi.org/10.3390/ geographies5020021 Copyright: © 2025 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https://creativecommons.org/ licenses/by/4.0/). Article Assessing the Impact of Groundwater Extraction and Climate Change on a Protected Playa-Lake System in the Southern Iberian Peninsula: La Ratosa Natural Reserve Miguel Rodríguez-Rodríguez 1,* , Laszlo Halmos 1, Alejandro Jiménez-Bonilla 1,* , Manuel Díaz-Azpiroz 1, Fernando Gázquez 2,3, Joaquín Delgado 4, Ana Fernández-Ayuso 5, Inmaculada Expósito 1, Sergio Martos-Rosillo 6and José Luis Yanes 1 1Department of Physical, Chemical and Natural Systems, Pablo de Olavide University, 41013 Seville, Spain; [email protected] (L.H.); [email protected] (M.D.-A.); [email protected] (I.E.); [email protected] (J.L.Y.) 2Water Resources and Environmental Geology Research Group, Department of Biology and Geology, University of Almeria, 04120 Almeria, Spain; [email protected] 3Andalusian Centre for Global Change—Hermelindo Castro (Engloba), University of Almería, 04120 Almería, Spain 4Department of Crystallography, Mineralogy and Agricultural Chemistry, University of Seville, 41004 Seville, Spain; [email protected] 5Department of Geology and Geochemistry, Autonomous University of Madrid, 28049 Madrid, Spain; [email protected] 6Geological Survey of Spain (IGME), Higher Council for Scientific Research (CSIC), 18071 Granada, Spain; [email protected] *Correspondence: mrodr[email protected] (M.R.-R.); [email protected] (A.J.-B.) Abstract: We modeled the water level variations in a protected playa-lake system ( La Ratosa Natural Reserve, S Spain) comprising two adjacent playa-lakes: La Ratosa and Herriza de los Ladrones. For this purpose, daily water balances were applied to reconstruct the water level. Model results were validated using actual water level monitoring over the past 20 years. We surveyed post-Pliocene geological structures in the endorheic watershed to investigate lake nucleation and to improve the hydrogeological model. Additionally, we investigated the groundwater level evolution in nearby aquifers, which have been profusely affected by groundwater exploitation for domestic and agricultural use. Then, the RCP 4.5 and RCP 8.5 climate change scenarios were applied to forecast the future of this lake system. We found that the playa-lake hydroperiod will shorten, causing the system to shift from seasonal to ephemeral, which appears to be a general trend in this area. However, the impact on the La Ratosa-Herriza de los Ladrones system would be likely more severe due to local stressors, such as groundwater withdrawal for urban demand and agriculture, driving the system to complete desiccation for extended periods. These results highlight the sensitivity of these protected ecosystems to changes in the watershed’s water balance and underscore the urgent need to preserve watersheds from any form of water use, other than ecological purposes. This approach aims to support informed decision-making to mitigate adverse impacts on these fragile ecosystems, ensuring their ecological integrity in the context of climate change and increasing water demand for various uses. Keywords: wetland hydrology; climate change; playa-lakes; ecosystem preservation; groundwater withdrawal 1. Introduction The origin and evolution of playa lakes are often influenced by both the presence of low-permeability rocks and active structures that may enclose endorheic watersheds. Geographies 2025,5, 21 https://doi.org/10.3390/geographies5020021 Geographies 2025,5, 21 2 of 19 These playa lakes, which have no surface outlets, periodically fill with water to form temporary ponds. In the Mediterranean climate, their water balance is negative, causing them to typically dry out during the summer. This delicate hydrological balance makes temporary playa lakes highly vulnerable to hydrological alterations in their watershed, particularly those caused by both human activities, like groundwater withdrawal, and shifts in local precipitation patterns due to climate change. Due to their high sensitivity, temporal playa-lakes serve as reliable indicators of both long-term environmental changes and local stressors, such as groundwater withdrawal in their watersheds [1]. The establishment of effective protection areas around these wetlands has traditionally been the primary approach to preventing or mitigating the most immediate threats to the survival of these ecosystems. However, these protection measures are generally limited to the wetland’s floodplain, limiting the consideration and monitoring of potential impacts within the broader watershed, such as groundwater withdrawal. The importance of groundwater in maintaining the hydroperiod of playa lakes has been largely demonstrated [ 2 – 4 ]. Recently, [ 1 ] proved that groundwater contributes significantly (81%) to the overall water flux of Ghorra playa, in Tunisia, with implications for the preservation of migratory birds, claimed that in Lake Atotonilko (Mexico) urgent public policies must be implemented to rationalize the use of water resources in the basin and ensure the minimum lake storage volume required to sustain its biodiversity. In the present study, we investigated the hydrology of the Nature Reserve “Laguna de la Ratosa”, in the north of the Málaga province (southern Spain), which comprises two adjacent playas, La Ratosa (RaL) and Herriza de los Ladrones (HL) (also called “Castañuela”), as well as a nameless ephemeral pond. Importantly, only the 22.7 hm 2 of former (RaL) that periodically floods is officially protected as a Reserve (Figure 1). HL playa-lake is outside the protected Reserve Zone and is only surrounded by a low-grade Peripheral Area of Protection (PAP). In 2015, a new Hydrological Protection Zone (HPZ) based on previous hydrological knowledge was proposed instead of the current Peripheral Area of Protection [ 5 ]. This new HPZ included the HL playa-lake and the western border of the La-Camorra karstic aquifer (Figure 1). As a part of that investigation, a monthly water balance was conducted in the playa-lake over a 10-year period (1998–2008), showing a strong correlation with observed water levels, confirming the playa-lake’s vulnerability to hydrological alterations caused by human activities, especially groundwater withdrawal in La-Camorra karstic aquifer. Despite the protection proposals made in the past, in recent years there has been a rapid deterioration of the wetland ecosystems in the protected area of La Ratosa Nature Reserve, largely due to the intensification of extreme climatic events, rising temperatures, and reduced precipitation. As a result, the water bodies have remained dry for most of the time. Even so, the desiccation periods of these playa-lakes appear to be longer in recent years than those of other wetlands in the region exposed to the same climatic conditions. Thus, it has become necessary to assess the factors conditioning this change in the water bodies’ hydroperiod, evaluating the extent of the impact of groundwater extractions in this regard and reassessing the protection zones accordingly. With this purpose, this study applies an interdisciplinary methodology with the aim to model the daily hydrological evolution of RaL and HL water levels for a 20-year period (2004–2024) and assess the susceptibility to climate change by applying the RCP 4.5 and RCP 8.5 scenarios, evaluating the vulnerability in the simulations. We also analyze the hydrogeological evolution of the La-Camorra aquifer within the Hydrological Protection zone during that period to detect changes in the piezometry and possible shifts in the hydrological regime of the playa-lakes. Geographies 2025,5, 21 3 of 19 Geographies 2025, 5, x FOR PEER REVIEW 3 of 19 Figure 1. Location of the study area. Red lines—country borders; Blue lines—playa-lake shorelines. Coordinates expressed in WGS84, radians. Finally, to strengthen information-driven conservation strategies, we compared Andalusian playa lakes with two playas in southern Hungary). Similarly, playa lakes on the Great Hungarian Plain face comparable challenges. Both regions experience a mix of continental and Mediterranean climatic influences, characterized by variable precipitation and high evapotranspiration. They also support specialized biota adapted to ephemeral water bodies, making their comparison valuable for developing conservation strategies in the face of climate change. 1.1. Geological Setting of La Ratosa Playa-Lake System La Ratosa playa-lake system is located in the external zones of the Betics chain. The Betics form the northern branch of the Gibraltar arc, built up because of the Miocene collision between the Alboran domain and the South Iberian and Maghrebian paleomargins and its tectonic activity still continues [6–9]. The South Iberian paleomargin is composed of: Triassic claystones, sandstones and evaporites, Jurassic dolostones and limestones, and Cretaceous to Paleogene marls and marly-limestones. The external zones of the Betics are deformed into a fold-and-thrust belt detached within the Triassic evaporites. Because of the tectonic load, the Guadalquivir foreland basin formed and was filled by a shallowing-upward sequence from marine to continental, upper Miocene to Holocene sediments [10]. The internal parts of this basin were incorporated into the fold-and-thrust belt due to the outward propagation of the deformation [8,9, 11]. Many playa-lakes and lakes develop during the Quaternary on the Betics fold-and-thrust belt [12]. The Ratosa playa-lake system is located in a relatively depressed zone within the Betics fold-and-thrust belt, known as the Antequera Depressed Area (ADA; [12]). The ADA, characterized by a roughly flat topography at approximately 450 m a.s.l, is limited by two topographic highs that coincide with two transpressional zones: the Algodonales-Badolatosa shear zone, to the N, and the Torcal shear zone, to the S [12]. The ADA includes some scattered reliefs such as the Humilladero Sierra, generated by a compressive bridge that links Figure 1. Location of the study area. Red lines—country borders; Blue lines—playa-lake shorelines. Coordinates expressed in WGS84, radians. Finally, to strengthen information-driven conservation strategies, we compared Andalusian playa lakes with two playas in southern Hungary). Similarly, playa lakes on the Great Hungarian Plain face comparable challenges. Both regions experience a mix of continental and Mediterranean climatic influences, characterized by variable precipitation and high evapotranspiration. They also support specialized biota adapted to ephemeral water bodies, making their comparison valuable for developing conservation strategies in the face of climate change. 1.1. Geological Setting of La Ratosa Playa-Lake System La Ratosa playa-lake system is located in the external zones of the Betics chain. The Betics form the northern branch of the Gibraltar arc, built up because of the Miocene collision between the Alboran domain and the South Iberian and Maghrebian paleomargins and its tectonic activity still continues [ 6 – 9 ]. The South Iberian paleomargin is composed of: Triassic claystones, sandstones and evaporites, Jurassic dolostones and limestones, and Cretaceous to Paleogene marls and marly-limestones. The external zones of the Betics are deformed into a fold-and-thrust belt detached within the Triassic evaporites. Because of the tectonic load, the Guadalquivir foreland basin formed and was filled by a shallowingupward sequence from marine to continental, upper Miocene to Holocene sediments [10]. The internal parts of this basin were incorporated into the fold-and-thrust belt due to the outward propagation of the deformation [ 8 , 9 , 11 ]. Many playa-lakes and lakes develop during the Quaternary on the Betics fold-and-thrust belt [12]. The Ratosa playa-lake system is located in a relatively depressed zone within the Betics fold-and-thrust belt, known as the Antequera Depressed Area (ADA; [ 12 ]). The ADA, characterized by a roughly flat topography at approximately 450 m a.s.l, is limited by two topographic highs that coincide with two transpressional zones: the AlgodonalesBadolatosa shear zone, to the N, and the Torcal shear zone, to the S [ 12 ]. The ADA includes some scattered reliefs such as the Humilladero Sierra, generated by a compressive bridge that links two post-Tortonian, left-lateral shear zones [ 12 ]. The La-Camorra and Mollina Geographies 2025,5, 21 4 of 19 ranges, made up of Jurassic limestones, bound the RaL and HL watersheds to the east (Figure 2). Geographies 2025, 5, x FOR PEER REVIEW 4 of 19 two post-Tortonian, left-lateral shear zones [12]. The La-Camorra and Mollina ranges, made up of Jurassic limestones, bound the RaL and HL watersheds to the east (Figure 2). Figure 2. Ratosa playa-lake system and La-Camorra aquifer. RaL stands for Ratosa playa-lake, and HL stands for Herriza de los Ladrones playa-lake. Official, proposed [5] and natural borders are defined in the figure’s legend. 1.2. Climatic Setting The climate of the southern Iberian Peninsula is typically Mediterranean, warm, and temperate (Csa; [13]. However, due to its location in the core of the Andalusian countryside, partially separated from the Mediterranean Sea by the Betic reliefs, the study area shows a noticeable continental influence, with a wide range of daily and annual temperatures. Temperatures may reach 0 °C in winter and more than 40 °C in summer. Precipitation is 456 mm/yr on average, and it concentrates on autumn and spring. Annual precipitation significantly changes from dry years (c. 300 mm/yr) to wet years (more than 800 mm) (Sierra de Yeguas station; Junta de Andalucía meteorological monitoring system). 1.3. Hydrological and Hydrogeological Setting La Ratosa playa-lake system is composed of La Ratosa (RaL) playa-lake which is officially protected as a Nature Reserve (orange border in Figure 2), the Herriza de los Ladrones (HL) playa lake, not protected as a Natural Reserve but inside the official Peripheral Area of Protection (PAP, see Figure 2) and an ephemeral nameless pond located in the northern sector. Nowadays both HL and the ephemeral pond are almost completely lost and classified as degraded systems according to hydrological and geochemical criteria [14], although under a natural regime, the system may have included the two playa-lakes and the pond, defining a pseudo-triangular shape with an approx. NNW-SSW long axis (Figure 3C). In fact, during extremely humid periods, both RaL and HR merged forming a single pond. As mentioned above, a Hydrological Protection Zone was proposed a decade ago [5] to try to protect and maintain the hydrological functioning and the ecological integrity of the system. To date, no change has been made in the Natural Reserve’s borders. La-Camorra karstic aquifer consists of Jurassic dolostone breccias, limestones, and marly limestones, forming a Figure 2. Ratosa playa-lake system and La-Camorra aquifer. RaL stands for Ratosa playa-lake, and HL stands for Herriza de los Ladrones playa-lake. Official, proposed [ 5 ] and natural borders are defined in the figure’s legend. 1.2. Climatic Setting The climate of the southern Iberian Peninsula is typically Mediterranean, warm, and temperate (Csa; [ 13 ]). However, due to its location in the core of the Andalusian countryside, partially separated from the Mediterranean Sea by the Betic reliefs, the study area shows a noticeable continental influence, with a wide range of daily and annual temperatures. Temperatures may reach 0 ◦ C in winter and more than 40 ◦ C in summer. Precipitation is 456 mm/yr on average, and it concentrates on autumn and spring. Annual precipitation significantly changes from dry years (c. 300 mm/yr) to wet years (more than 800 mm) (Sierra de Yeguas station; Junta de Andalucía meteorological monitoring system). 1.3. Hydrological and Hydrogeological Setting La Ratosa playa-lake system is composed of La Ratosa (RaL) playa-lake which is officially protected as a Nature Reserve (orange border in Figure 2), the Herriza de los Ladrones (HL) playa lake, not protected as a Natural Reserve but inside the official Peripheral Area of Protection (PAP, see Figure 2) and an ephemeral nameless pond located in the northern sector. Nowadays both HL and the ephemeral pond are almost completely lost and classified as degraded systems according to hydrological and geochemical criteria [ 14 ], although under a natural regime, the system may have included the two playa-lakes and the pond, defining a pseudo-triangular shape with an approx. NNW-SSW long axis (Figure 3C). In fact, during extremely humid periods, both RaL and HR merged forming a single pond. As mentioned above, a Hydrological Protection Zone was proposed a decade ago [ 5 ] to try to protect and maintain the hydrological functioning and the ecological integrity of the system. To date, no change has been made in the Natural Reserve’s borders. La-Camorra karstic aquifer consists of Jurassic dolostone breccias, limestones, and marly limestones, forming Geographies 2025,5, 21 5 of 19 a carbonate aquifer above a low-permeable unit. Overlaying these materials, there are moderately permeable late Tortonian calcareous sandstone, sands, marls, and Quaternary detrital sediments. Historically, the carbonate aquifer discharged into the Alameda Spring, which has been dry since 1982. Currently, the flow is diverted towards several pumps (some of them, but not all, are shown in Figure 2) which supply water to the village of Alameda. Previous works confirmed the hydrogeological connection between the Mollina and La-Camorra ranges, suggesting they constitute a single carbonate aquifer [5,15]. Geographies 2025, 5, x FOR PEER REVIEW 5 of 19 carbonate aquifer above a low-permeable unit. Overlaying these materials, there are moderately permeable late Tortonian calcareous sandstone, sands, marls, and Quaternary detrital sediments. Historically, the carbonate aquifer discharged into the Alameda Spring, which has been dry since 1982. Currently, the flow is diverted towards several pumps (some of them, but not all, are shown in Figure 2) which supply water to the village of Alameda. Previous works confirmed the hydrogeological connection between the Mollina and LaCamorra ranges, suggesting they constitute a single carbonate aquifer [5,15]. Figure 3. (A,B) cross-section showing the playa-lakes bathymetry and morphology. (C) Ortopicture from 2010 (wet year) when HL and RaL are merged. 2. Materials and Methods 2.1. Water Level Monitoring We obtained actual water levels from the Junta de Andalucía wetlands monitoring agency both for the La Ratosa system and for other lakes (e.g., Archidona Lakes) and playalakes (e.g., Campillos playa-lakes) for the sake of comparison. Water level monitoring was conducted by recording measurements of calibrated staff gauges of the deepest areas of the RaL, HL, and the rest of the playa-lakes. Actual data have a centimetric accuracy. Monitoring was carried out from January 2005 to February 2025. These data were used to calibrate our model. Moreover, some ortophotographies from IGN (National Geographic Institute) were used to calibrate some parameters. Figure 3. (A,B) cross-section showing the playa-lakes bathymetry and morphology. (C) Ortopicture from 2010 (wet year) when HL and RaL are merged. 2. Materials and Methods 2.1. Water Level Monitoring We obtained actual water levels from the Junta de Andalucía wetlands monitoring agency both for the La Ratosa system and for other lakes (e.g., Archidona Lakes) and playalakes (e.g., Campillos playa-lakes) for the sake of comparison. Water level monitoring was conducted by recording measurements of calibrated staff gauges of the deepest areas of the RaL, HL, and the rest of the playa-lakes. Actual data have a centimetric accuracy. Monitoring was carried out from January 2005 to February 2025. These data were used to calibrate our model. Moreover, some ortophotographies from IGN (National Geographic Institute) were used to calibrate some parameters. Geographies 2025,5, 21 6 of 19 2.2. Water Level Modelling The water level modeling has been applied previously to other lakes and playa-lakes in southern Spain (e.g., [ 12 ]). For modeling, we used climatic parameters (precipitation, average daily temperature, and ET ◦ ) from the Sierra de Yeguas station; Junta de Andalucía meteorological monitoring system, located 15 km to the SE from La Ratosa playa-lake and at a height of 467 m a.s.l. We performed the modelling for 20 years including a wet period from 2010 to 2013, when RaL and HL merged. This modeling is based on changes in water level with depth and time, thus we produced 2D water balances of both playa-lakes. Due to the presence of low permeability rocks on the playa-lake beds: Triassic claystone, the lake water storage (Hs) may be simplified into: Hs=P+BD±O−E (1) Water inputs are precipitation (P), basin discharge (BD), and overflows from another wetland (O). P is the increase in the lake level due to precipitation directly obtained from the weather station. BD is calculated by means of a soil water balance. To do that, we used the TRASERO software (1.0) to calculate the effective rainfall and we chose a water holding capacity of 220 mm according to clayey soils. This value is similar to that used for other works (e.g., [ 12 ]). Once the effective rainfall is calculated, we multiply by the watershed/average flooded surface (W/AFS) to obtain the increase in mm of the playa-lake water level, as in previous works [ 12 ]. Most years, the HL and RaL do not behave as an only wetland, then we made calculations separately. In RaL playa-lake W/AFS relationship is 24, whilst in HL relationship is 16 (Table 1). During wet years (from 2010 to 2013), the flooded surface considerably increased and RaL and HL playa-lakes merged into one water body (Figure 3). For this period, we used a W/AFS of 15 for both playa-lakes. The RaL bed is located at 448 m. During wet years, the RaL water level increases, and when it reaches 3.3 m, this playa-lake merges with HL. Table 1. Watershed and flooded area used for modeling. Watershed (hm2) Flooded Area (hm2)Relationship (W/Flooded Área) RaL 557 23 24 average year HL 150 9.2 16 average year Ratosa system 797 52 15 wet year (water level > 3 m) The main water output for these water bodies is evaporation (E). It is calculated as the water output as direct evaporation from an open water body. We used the potential evapotranspiration (PET) by the Hargreaves method [ 16 ] calculated by means of the maximum and minimum temperature records. We corrected these values by multiplying by 1.15 to calculate direct evapotranspiration from an open water body as in previous works [ 12 ]. The result of the water balance (Hs) is added to the lake water level of the previous day. We validate the model using the ordinary least squares method by comparing actual and modeled data. 2.3. Climate Change Scenarios Once the models were validated, we applied climate change scenarios for the period from 2030 to 2060. To do that, we performed daily water balances, and we calculated the playa-lake water storage (Hs) using Equation (1). For these calculations, we obtained climatic parameters from [ 17 ]. We used two IPCC climate change scenarios: RCP 4.5 and 8.5, as an intermediate mitigation and as more extreme climate change scenarios. Global Geographies 2025,5, 21 7 of 19 temperature is projected to increase between 1.4 and 2 ◦ C and between 2.6 and 4.8 ◦ C for 2100 for the RCP 4.5 and 8.5, respectively [ 18 ]. We assumed a water level of 1 m and 0.5 m for the RaL and HL, respectively, in 2030 as the initial condition for the modeling process. These values are the average water level during the studied period. 2.4. Structural Data To improve the hydrogeological model, we collected field data and improved previous geological maps. We obtained these data from the Sierra de la Camorra and Mollina, which are within the La Ratosa system watershed. We focused on structures that affect post-Pliocene sediments. 3. Results 3.1. Geological Results The Sierra de la Camorra and Mollina mountain ranges are composed of Jurassic dolostones and limestones with bedding dipping 15–60 ◦ towards the NW (Figure 4a). These ranges are limited to the NW by fault surfaces striking N10 ◦ E to N80 ◦ E that mostly dip 65–90 ◦ towards the SE (Figure 4b). Slicklines together with shear-sense criteria show that they are reverse faults with a subordinate dextral strike-slip movement. These faults cut and displace quaternary soils and piedmont deposits. Towards the W of RaL, a kilometric scale, NE-SW antiform folds Miocene units (Figure 4a). Geographies 2025, 5, x FOR PEER REVIEW 7 of 19 2.4. Structural Data To improve the hydrogeological model, we collected field data and improved previous geological maps. We obtained these data from the Sierra de la Camorra and Mollina, which are within the La Ratosa system watershed. We focused on structures that affect post-Pliocene sediments. 3. Results 3.1. Geological Results The Sierra de la Camorra and Mollina mountain ranges are composed of Jurassic dolostones and limestones with bedding dipping 15–60° towards the NW (Figure 4a). These ranges are limited to the NW by fault surfaces striking N10° E to N80° E that mostly dip 65–90° towards the SE (Figure 4b). Slicklines together with shear-sense criteria show that they are reverse faults with a subordinate dextral strike-slip movement. These faults cut and displace quaternary soils and piedmont deposits. Towards the W of RaL, a kilometric scale, NE-SW antiform folds Miocene units (Figure 4a). Figure 4. (a) Geological map of RaL area, (b) stereo plot of main faults, and (c,d) well data from Ratosa and Santaella wells (red dots). To improve the structural information of the area, we have interpreted two shallow wells (up to 80 m depth) located in the studied area: Ratosa and Serafina wells (see location in Figure 4a). Both well logs show Jurassic limestones from 80 to 20–40 m, and Quaternary deposits (soils, piedmont and lake deposits in Ratosa well, only soils in Serafina well) on top (Figure 4c,d). In Serafina well, upper Miocene marls appear between the limestones and the Quaternary soils. Consequently, the Jurassic limestones sheet that crops out in the la Camorra and Mollina mountain ranges continues towards the NW, underlying the RaL. It is noteworthy that the long axis of the flooded area is approx. N45° E, thus it runs subparallel to the average fault and fold-axis orientation (Figure 4). Figure 4. (a) Geological map of RaL area, (b) stereo plot of main faults, and (c,d) well data from Ratosa and Santaella wells (red dots). To improve the structural information of the area, we have interpreted two shallow wells (up to 80 m depth) located in the studied area: Ratosa and Serafina wells (see location in Figure 4a). Both well logs show Jurassic limestones from 80 to 20–40 m, and Quaternary deposits (soils, piedmont and lake deposits in Ratosa well, only soils in Serafina well) on top (Figure 4c,d). In Serafina well, upper Miocene marls appear between the limestones and the Quaternary soils. Consequently, the Jurassic limestones sheet that crops out in Geographies 2025,5, 21 8 of 19 the la Camorra and Mollina mountain ranges continues towards the NW, underlying the RaL. It is noteworthy that the long axis of the flooded area is approx. N45 ◦ E, thus it runs subparallel to the average fault and fold-axis orientation (Figure 4). 3.2. Water Level Variations, Modelling and Validation In this section, we describe the results derived from the water level monitoring, modeling, and validation. We distinguished a wet period according to P and effective rainfall values from 2010 to 2013. During this period, precipitation exceeds 600 mm/yr. During average years, precipitation is 450 mm/yr on average, effective rainfall is lower than 20 mm/yr and evaporation is approx. 1500 mm/yr, then playa-lakes dry up during summer (from June to October; Figures 5and 6). In the case of RaL water level may reach 1.5 m, whilst in HL does not reach 1 m. This is due to the lower W/AFS relationship of HL (Table 1). Both behave as seasonal playa-lakes. During dry years, both playa-lakes remain dry most of the days (ephemeral water bodies), even during autumn, spring, and winter (Figures 5and 6). This is due to the low precipitation values (lower than 400 mm/y) and effective rainfall (lower than 20 mm/y). Geographies 2025, 5, x FOR PEER REVIEW 8 of 19 3.2. Water Level Variations, Modelling and Validation In this section, we describe the results derived from the water level monitoring, modeling, and validation. We distinguished a wet period according to P and effective rainfall values from 2010 to 2013. During this period, precipitation exceeds 600 mm/yr. During average years, precipitation is 450 mm/yr on average, effective rainfall is lower than 20 mm/yr and evaporation is approx. 1500 mm/yr, then playa-lakes dry up during summer (from June to October; Figures 5 and 6). In the case of RaL water level may reach 1.5 m, whilst in HL does not reach 1 m. This is due to the lower W/AFS relationship of HL (Table 1). Both behave as seasonal playa-lakes. During dry years, both playa-lakes remain dry most of the days (ephemeral water bodies), even during autumn, spring, and winter (Figures 5 and 6). This is due to the low precipitation values (lower than 400 mm/y) and effective rainfall (lower than 20 mm/y). In Figure 5 the hydrograms of RaL (Figure 5a) and HL (Figure 5b) during the studied period (2005–2025) are displayed, as well as the linear regression of the water level. During the wet period, from January 2010, the RaL water level quickly increased up to 3.3 m above the playa-lake bed. When this water level is reached, both playa-lakes merge into a single water body (Figures 3C and 5c). Even though they are merged, a difference of c. 35 cm in total depth is observed in the hydrograph of both playa-lakes (Figure 5c). This difference between RaL and HL is due to the different elevation of the lakebed (448 m a.s.l. and 448.33 m a.s.l., respectively). Figure 5. (a,b) Hydrograms of RaL and HL during the studied period (2005–2025). (c) A detail of a wet period (01/2010 to 03/2011) is shown. Yellow circle represents the moment of merging in RaL and HL, the last time registered in the year 2011. (d) The most recent rainfall period (18/04/2023 to 31/01/2025) is shown, during which both RaL and HL remained completely dry. Note that HL has been dry since 2014 and RaL has been dry since 18/04/2023 although the total precipitation in the area from April 2023 to January 2025 has been 630 mm (Figure 5d). Figure 6 shows the water level modeling of the RaL and HL. We showed in yellow when both playa-lakes are connected. Towards the N, we observed another flooded area Figure 5. (a,b) Hydrograms of RaL and HL during the studied period (2005–2025). (c) A detail of a wet period (01/2010 to 03/2011) is shown. Yellow circle represents the moment of merging in RaL and HL, the last time registered in the year 2011. (d) The most recent rainfall period (18/04/2023 to 31/01/2025) is shown, during which both RaL and HL remained completely dry. In Figure 5the hydrograms of RaL (Figure 5a) and HL (Figure 5b) during the studied period (2005–2025) are displayed, as well as the linear regression of the water level. During the wet period, from January 2010, the RaL water level quickly increased up to 3.3 m above the playa-lake bed. When this water level is reached, both playa-lakes merge into a single water body (Figures 3C and 5c). Even though they are merged, a difference of c. 35 cm in total depth is observed in the hydrograph of both playa-lakes (Figure 5c). This difference between RaL and HL is due to the different elevation of the lakebed (448 m a.s.l. and 448.33 m a.s.l., respectively). Geographies 2025,5, 21 9 of 19 Geographies 2025, 5, x FOR PEER REVIEW 9 of 19 during wet years, although we do not have monitoring data. This flooded area is separated from the RaL and HL by a road (Figure 3). This flooded area also remained flooded during this wet period. All these three water bodies probably formed only playa-lake prior to human activity. It should be noted that there is a sharp contrast in the water level between average and wet periods (Figure 6). Figure 6. Water level modeling of the RaL and HL playa-lakes. Red: Actual data. Blue: Modelled data. Yellow color shows the period when both playa-lakes merged. Water level modeling adjusts to actual data, except for some periods. For example, actual data are above modeled data during the wet period in RaL (Figure 6). Statistical analysis shows a strong relationship in both cases (R2 > 0.97; Figure 7). Once the models were validated, we applied climate change scenarios. Figure 7. Statistical analysis derived from the ordinary least squares. 3.3. Climate Change Scenarios In both, RCP 4.5 and 8.5 climate change scenarios, long dry periods with evaporation rates higher than 2000 mm/yr alternated with periods with extreme precipitation events, Figure 6. Water level modeling of the RaL and HL playa-lakes. Red: Actual data. Blue: Modelled data. Yellow color shows the period when both playa-lakes merged. Note that HL has been dry since 2014 and RaL has been dry since 18/04/2023 although the total precipitation in the area from April 2023 to January 2025 has been 630 mm (Figure 5d). Figure 6shows the water level modeling of the RaL and HL. We showed in yellow when both playa-lakes are connected. Towards the N, we observed another flooded area during wet years, although we do not have monitoring data. This flooded area is separated from the RaL and HL by a road (Figure 3). This flooded area also remained flooded during this wet period. All these three water bodies probably formed only playa-lake prior to human activity. It should be noted that there is a sharp contrast in the water level between average and wet periods (Figure 6). Water level modeling adjusts to actual data, except for some periods. For example, actual data are above modeled data during the wet period in RaL (Figure 6). Statistical analysis shows a strong relationship in both cases (R 2 > 0.97; Figure 7). Once the models were validated, we applied climate change scenarios. Geographies 2025, 5, x FOR PEER REVIEW 9 of 19 during wet years, although we do not have monitoring data. This flooded area is separated from the RaL and HL by a road (Figure 3). This flooded area also remained flooded during this wet period. All these three water bodies probably formed only playa-lake prior to human activity. It should be noted that there is a sharp contrast in the water level between average and wet periods (Figure 6). Figure 6. Water level modeling of the RaL and HL playa-lakes. Red: Actual data. Blue: Modelled data. Yellow color shows the period when both playa-lakes merged. Water level modeling adjusts to actual data, except for some periods. For example, actual data are above modeled data during the wet period in RaL (Figure 6). Statistical analysis shows a strong relationship in both cases (R2 > 0.97; Figure 7). Once the models were validated, we applied climate change scenarios. Figure 7. Statistical analysis derived from the ordinary least squares. 3.3. Climate Change Scenarios In both, RCP 4.5 and 8.5 climate change scenarios, long dry periods with evaporation rates higher than 2000 mm/yr alternated with periods with extreme precipitation events, Figure 7. Statistical analysis derived from the ordinary least squares. Geographies 2025,5, 21 16 of 19 emphasize the need for scientifically based protection measures. The shared challenges of these ecosystems offer valuable insights into the complex interactions between hydrology, land use, and climate change, ultimately informing more resilient management practices for these vulnerable systems. The first and most important step is returning to historic hydrological functioning [ 32 ]. The protection of the watershed and the recharge zones by monitoring as well as the regulation of water extraction and use, land-use changes, and the presence of pollutants are essential. It is very important to highlight that the ecosystem of playa-lakes depends heavily on groundwater chemistry [ 24 ]. Additionally, restoration measures should focus on rehabilitating already degraded aquatic ecosystems, such as the HL. Wetland restoration aims to reverse the degradation of wetlands and enhance their ecological functions and integrity focusing on the three fundamental components that define wetlands: hydrology, soils, and vegetation [ 4 ]. 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 been 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 [ 32 ]. 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 with an intense exploitation of aquifers in semiarid climates. Those impacts include agricultural decline, population migration, public health risks, and economic instability [ 33 ]. Finally, future research should focus on long-term monitoring using advanced remote sensing technologies to capture temporal changes and predict future trends [ 34 ]. 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 [ 34 ], these directions provided a comprehensive framework to address the complex challenges faced by these critical ecosystems. 5. Conclusions The analysis of water level variations and the hydrogeological modeling of La Ratosa Natural Reserve, which includes two playa-lakes (RaL and HL playa-lakes), reveals significant findings. By applying daily water balances and validating them with 20 years of actual measurements, a water level model could be successfully developed. The validated model was then subjected to RCP 4.5 and RCP 8.5 climate change scenarios. Additionally, the groundwater level trends in the area’s aquifers, heavily impacted by domestic and agricultural exploitation, were analyzed. The results indicate a reduction in the playa-lake hydroperiod, shifting from seasonal to ephemeral, a trend exacerbated by local stressors, leading to near-complete desiccation and irreversible conditions. This underscores the extreme sensitivity of these protected ecosystems to changes in watershed water balance and highlights the urgent need for establishing Hydrological Protection Zones (HPZs) coinciding with watershed boundaries and preserving such watersheds from non-ecological water uses. 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 Geographies 2025,5, 21 17 of 19 would also address the socio-economic and environmental consequences of over-extraction. As a future objective, it will be necessary to establish a monitoring program, to track changes in biodiversity, water quality, and habitat conditions. The comparative analysis with similar, yet distant ecosystems facing the same challenges further emphasizes the importance of conserving these landmarks through the understanding of their hydrological functioning and the adoption of appropriate measures. The study aims to inform decisionmaking to mitigate adverse impacts on these fragile ecosystems, ensuring their ecological integrity amidst evolving climate conditions and increasing water demand. Author Contributions: Conceptualization, M.R.-R., L.H., A.J.-B. and A.F.-A.; methodology, M.R.-R. and A.J.-B.; validation, J.L.Y., I.E., M.D.-A., A.F.-A. and S.M.-R.; formal analysis, F.G.; investigation, M.R.-R., L.H., A.J.-B., F.G. and A.F.-A.; data curation, M.R.-R. and A.J.-B.; writing—original draft preparation, M.R.-R., A.J.-B. and L.H.; writing—review and editing, M.D.-A., F.G., J.D., A.F.-A., J.L.Y., I.E and S.M.-R.; visualization, M.R.-R., A.J.-B. and J.D.; supervision, M.R.-R. and F.G.; project administration, M.R.-R. and F.G.; funding acquisition, M.R.-R., F.G. and A.J.-B. All authors have read and agreed to the published version of the manuscript. Funding: This study was supported by the (1) Tectonic conditioning and climate change effects on the hydrogeological evolution of wetlands and playa-lakes in the southern Spain research project (University of Pablo de Olavide), (2) GYPCLIMATE research project (PID2021-123980OA-I00) Spanish Ministry of Economy and Competitiveness—Regional Development European Fund (FEDER), (3) the project PGC2018-100914-B-I00, funded by the Ministerio de Ciencia e Innovacíon (Spanish Government)/AEI/10.13039/501100011033/ERDF, (4) the project UPO-1259543, funded by the Consejería de Economía, Conocimiento, Compañías y Universidad (Andalusian Government)/ERDF and (5) “Monitorizacion hidrológica y modelización de la relación laguna-acuífero en los mantos eólicos de Doñana. Seguimiento y ampliación del inventario” (Agreement between the Guadalquivir River Basin Authority and the University Pablo de Olavide). F.G acknowledges the Ramón y Cajal fellowship, RYC2020-029811-I, and the grant PPIT-UAL, Junta de Andalucía-FEDER 2022-2026 (RyC-PPI2021-01). Data Availability Statement: The original contributions presented in this study are included in the article. Further inquiries can be directed to the corresponding authors. Conflicts of Interest: The authors declare no conflict of interest. References 1. Meza-Rodríguez, D.; Anda, J.; Shear, H. Lake Atotonilco: A first approach to determining the minimum lake level necessary to sustain its biodiversity. Ann. Am. Assoc. Geogr. 2023,113, 2318–2332. [CrossRef] 2. Gil-Márquez, J.M.; Andreo, B.; Mudarra, M. Comparative analysis of runoff and evaporation assessment methods to evaluate wetland–groundwater interaction in Mediterranean evaporitic-karst aquatic ecosystem. Water 2021,13, 1482. [CrossRef] 3. Yang, Z.; Hu, L.H.; Zhang, W. Hydrochemical Characteristics of Groundwater and Their Significance in Arid Inland Hydrology. Water 2023,15, 1641. [CrossRef] 4. Fessahaye, A.K.; Xie, Y.; Hu, Y.; Dai, G.; Zheng, H.; Teng, W. Groundwater Over-Extraction: Comprehensive Review of Socio-economic Impacts and Pathways to Sustainable Management. Eur. J. Theor. Appl. Sci. 2025,3, 190–211. [CrossRef] 5. Rodríguez-Rodríguez, M.; Martos-Rosillo, S.; Pedrera, A.; Benavente-Herrera, J. Ratosa playa lake in southern Spain. Karst pan or compound sink? Environ. Monit. Assess. 2015,187, 175. [CrossRef] 6. Azañón Hernández, J.M.; Pérez-Peña, J.V.; Giaconia, F.; Booth-Rea, G.; Martínez Martínez, J.M.; Rodríguez-Peces, M.J. Active tectonics in the central and eastern Betic Cordillera through morphotectonic analysis: The case of Sierra Nevada and Sierra Alhamilla. J. Iber. Geol. 2012,38, 225–238. 7. Marín-Lechado, C.; Pedrera Parias, A.; Ruiz Constán, A.; Peláez Montilla, J.A.; González Ramón, A. Deformation pattern of the Eastern Guadalquivir foreland basin (Southern Spain). Tectonics 2018,36, 1072–1089. [CrossRef] 8. González-Castillo, L.; Galindo-Zaldívar, J.; Pedrera, A.; Martínez-Moreno, F.J.; Ruano, P. Shallow frontal deformation related to active continental subduction: Structure and recent stresses in the westernmost Betic Cordillera. Terra Nova 2015,27, 114–121. [CrossRef] Geographies 2025,5, 21 18 of 19 9. Ruiz-Constán, A.; Pedrera, A.; Galindo-Zaldívar, J.; Pous, J.; Arzate, J.; Roldán-García, F.J.; Anahnah, F. Constraints on the frontal crustal structure of a continental collision from an integrated geophysical research: The central-western Betic Cordillera (SW Spain). Geochem. Geophys. Geosystems 2012,13, 1–19. [CrossRef] 10. Garcia–Castellanos, D.; Fernandez, M.; Torné, M. Modeling the evolution of the Guadalquivir foreland basin (southern Spain). Tectonics 2002,21, 91917. [CrossRef] 11. Ruano, P.; Galindo-Zaldívar, J.; Jabaloy, A. Recent tectonic structures in a transect of the Central Betic Cordillera. Pure Appl. Geophys. 2004,161, 541–563. [CrossRef] 12. Jiménez-Bonilla, A.; Martegani, L.; Rodríguez-Rodríguez, M.; Gázquez, F.; Díaz-Azpíroz, M.; Martos, S.; Expósito, I. The role of neotectonics and climate variability in the Pleistocene-to-Holocene hydrological evolution of the Fuente de Piedra playa lake (southern Iberian Peninsula). Hydrol. Earth Syst. Sci. 2024,28, 5311–5329. [CrossRef] 13. Essenwanger, O.M. General Climatology 1C: Classification of Climates; Elsevier: Amsterdam, The Netherlands, 2001. 14. Halmos, L.; Delgado Rodríguez, J.M.; Rodríguez Rodríguez, M.; Jiménez Bonilla, A.; Díaz Azpiroz, M. Physicochemical characteristics of playa-lake sediments located in the western External Betics. Geogaceta 2022,72, 39–42. [CrossRef] 15. Pedrera, A.; Martos-Rosillo, S.; Galindo-Zaldívar, J.; Rodríguez-Rodríguez, M.; Benavente, J.; Martín-Rodríguez, J.F.; ZúñigaLópez, M.I. Unravelling aquifer-wetland interaction using CSAMT and gravity methods: The Mollina-Camorra aquifer and the Fuente de Piedra playa-lake, southern Spain. J. Appl. Geophys. 2016,129, 17–27. [CrossRef] 16. Hargreaves, G.H.; Samani, Z.A. Reference crop evapotranspiration from temperature. Appl. Eng. Agric. 1985,1, 96–99. [CrossRef] 17. Montes-Vega, M.J.; Guardiola-Albert, C.; Rodríguez-Rodríguez, M. Calculation of the SPI, SPEI, and GRDI Indices for Historical Climatic Data from Doñana National Park: Forecasting climatic series (2030–2059) using two climatic scenarios RCP 4.5 and RCP 8.5 by IPCC. Water 2023,15, 2369. [CrossRef] 18. Daniel, D.W.; Smith, L.M.; McMurry, S.T.; LaGrange, T.; Stutheit, R.; Tangen, B.A.; Dahl, C.F. Greenhouse Gas Fluxes and Carbon Storage Dynamics in Playa Wetlands: Restoration Potential to Mitigate Climate Change. In Conservation Effects Assessment Project (CEAP)—Wetlands, Science Note; United States Department of Agriculture (USDA); Natural Resources Conservation Service (NRCS): Washington, DC, USA, 2016; p. 7. 19. Kohfahl, C.; Rodriguez, M.; Fenk, C.; Menz, C.; Benavente, J.; Hubberten, H.; Pekdeger, A. Characterising flow regime and interrelation between surface-water and ground-water in the Fuente de Piedra salt lake basin by means of stable isotopes, hydrogeochemical and hydraulic data. J. Hydrol. 2008,351, 170–187. [CrossRef] 20. Sociedad Geologica de España. Geología de España; Vera, J.A., Ed.; SGE-IGME: Madrid, Spain, 2004. 21. Suppe, J.; Sàbat, F.; Munoz, J.A.; Poblet, J.; Roca, E.; Vergés, J. Bed-by-bed fold growth by kink-band migration: Sant Llorenç de Morunys, eastern Pyrenees. J. Struct. Geol. 1997,19, 443–461. [CrossRef] 22. Gurdak, J.J.; Roe, C.D. Recharge Rates and Chemistry Beneath Playas of the High Plains Aquifer—A Literature Review and Synthesis; Prepared in Cooperation with Playa Lakes Joint Venture; U.S. Geological Survey Circular 1333: Denver, CO, USA, 2009; p. 39. 23. Labbe, J.; Celle, H.; Devidal, J.; Albaric, J.; Mailhot, G. Combined Impacts of Climate Change and Water Withdrawals on the Water Balance at the Watershed Scale—The Case of the Allier Alluvial Hydrosystem (France). Sustainability 2023,15, 3275. [CrossRef] 24. Zhang, H.; Tang, Z.; Bishop, A.; Drahota, J.; LaGrange, T.; Varner, D. Conservation significantly improves wetland conditions: Evaluation of playa wetlands in different conservation status. Wetl. Ecol. Manag. 2020,28, 85–102. [CrossRef] 25. Busa-Fekete, B.; Hegyi, R.; Szanyi, J. The hydrogeological aspects of Lake Fehér, Kardoskút, Southern Hungary. Acta Mineral. Petrogr. 2003,44, 35–41. 26. Sümegi, P.; Lócskai, T.; Hupuczi, J. Late Quaternary palaeoenvironment and palaeoclimate of the Lake Fehér (Fehér-tó) sequence at Kardoskút (South Hungary), based on preliminary mollusc records. Open Geosci. 2011,3, 43–52. [CrossRef] 27. Rakonczai, J.; Bódis, K. A Környezeti Változások Következményei az Alföld Felszín Alatti Vízkészleteiben. Jakucs, L., Ed.. Ph.D. Thesis, University of Szeged, Szeged, Hungary, 2002; pp. 227–238. 28. Rakonczai, J. A Klímaváltozás Következményei a Dél-Alföldi Tájon (A Természeti Földrajz Változó Szerepe és Lehet˝oségei)—The consequences of climate change in the Southern Great Plain (The changing role and possibilities of physical geography). Ph.D. Thesis, Hungarian Academy of Sciences, Szeged, Hungary, 2013; p. 167. 29. Biró, M.; Révész, A.; Molnár, Z.; Horváth, F. Regional habitat pattern of the Danube–Tisza Interfluve in Hungary, I: The landscape structure and habitat pattern; the fen and alkali vegetation. Acta Bot. Hung. 2007,49, 267–303. [CrossRef] 30. Tóth, T. Dynamics of Salt Accumulation in the Danube Valley. International Salinity Forum; Oral Presentation Abstracts; Riverside: Rolling Meadows, IL, USA, 2005; pp. 449–452. 31. Halmos, L.; Bozsó, G.; Pál-Molnár, E. Alkaline lake system in Danube and Tisza interfluve (Szeged, HU)—Climate change and landscape degradation. Visegr. J. Bioeconomy Sustain. Dev. 2014,3, 77–81. [CrossRef] 32. Poff, N.L.; Zimmerman, J.K. Ecological responses to altered flow regimes: A literature review to inform the science and management of environmental flows. Freshw. Biol. 2010,55, 194–205. [CrossRef] Geographies 2025,5, 21 19 of 19 33. Hiraga, Y.; Kazama, S.; Ekkawatpanit, C.; Touge, Y. Impact of reclamation on the environment of the lower Mekong river basin. J. Hydrol. Reg. Stud. 2018,18, 143–155. [CrossRef] 34. Zhang, B.; Niu, Z.; Zhang, D.; Huo, X. 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 Sens. 2022,14, 4147. [CrossRef] Disclaimer/Publisher’s Note: The statements, opinions and data contained in all publications are solely those of the individual author(s) and contributor(s) and not of MDPI and/or the editor(s). MDPI and/or the editor(s) disclaim responsibility for any injury to people or property resulting from any ideas, methods, instructions or products referred to in the content.