Assesing the hydrogeological functioning of an evaporite karst system coupling tritium and physicochemical data

Discharge rate, electrical conductivity and water temperature have been continuously recorded in an evaporite karst spring located in S Spain and 3H determinations of spring water were performed. Results evidence a complex hydrogeological functioning, including rapid conduit flows (unsaturated zone), and diffuse flow (saturated zone) with diverse residence time within the systemUniversidad de Málaga. Campus de Excelencia Internacional Andalucía Tech International Atomic Energy Agency (IAEA

Considerations about wastewater reuse in areas subjected to strong pressures in the South of Spain

Treated wastewater reuse is essential for water supply in areas where the pressure over water resources is high. This is the case of Costa del Sol and the Guadal-horce Valley, where a lot of water is required for urban, agricultural and recrea-tional uses. Most of this water is coming from natural sources instead of being reused, which percentage varies over Spain. In these areas, located in the Málaga province (Andalucía region), less than 6% of treated wastewater is assigned for any kind of use (garden irrigation and golf courses is the major one). Trying to solve this lack of reclaimed water, a wetlands restoration project was carried out in the Guadalhorce River Mouth, near the city of Málaga. Several lagoons were created using treated wastewater. Results were satisfactory with a clear increase in biodiversity, but employing a reduced amount of replenished water, due to the very strict requirements of the regional government. So, a great effort must be done to improve water reusing, especially in parts were freshwater is scarce (like S Spain and Mediterranean area), but also to hire well trained techniciansAsociación Internacional de Hidrogeólogos, Grupo Portugués International Association for Promoting Geoethics Instituto Superior de Engenharía de Porto Asociación Internacional de Hidrogeólogos, Grupo Españo

Hydrogeological parameters assessment by tidal influence analysis in the coastal aquifers of Bajo Guadalhorce (Malaga province, southern Spain)

By the use of continuous data recording on two points of the Bajo Guadalhorce coastal sector (Malaga province, southern Spain), located at 626 m and 985 m inland, it has been possible to verify a clear influence of tidal oscillations on the water table of the unconfined and the confined aquifers. Various methods to estimate aquifer transmissivity have been applied. The results depends on the method and, more important, on the storage coefficient (S) values. After the calculations it is possible to confirm that the time lag and tidal efficiency factor methods give coherent results with previous data, although with the time lag method the transmissivity values are an order of magnitude higherEl registro continuo de las variaciones piezométricas en dos puntos del sector costero del Bajo Guadalhorce (Málaga), ubicados a 626 m y 985 m de la línea de costa, ha permitido constatar la influencia de las oscilaciones mareales en los niveles piezométricos de los acuíferos libre y confinado. Se han podido aplicar varias metodologías para estimar la transmisividad de ambos. Los resultados dependen del método utilizado y, en mayor medida, de los valores de coeficiente de almacenamiento (S). Tras los cálculos se puede afirmar que las metodologías de retraso de mareas y eficiencia de mareas presentan resultados coherentes con los datos previos, aunque con el método de retraso de mareas se obtienen valores de transmisividad de hasta un orden de magnitud mayore

Towards a better understanding of flow-related processes in the vertically distributed compartments of karst aquifers by combining natural tracers and stable isotopes

Understanding infiltration pathways throughout the different compartments of karst systems (soil-epikarst-unsaturated zone-saturated zone) is vital to assess recharge processes, vulnerability to pollution, and the general hydrogeological functioning of these kind of aquifers. To gain deeper insight into the soil-water-rock hydrogeochemical processes occurring throughout the vertically hierarchized compartments of the aquifer and to evaluate the applicability of different soil natural parameters as groundwater flow tracers, the present work analyzes the spatial and temporal evolution of total organic carbon -TOC-, intrinsic fluorescence related to organic matter, nitrates, δ13CTDIC, and the values of stable isotopes of δ2H and δ18O from water molecules and at different sampling points in a geologically complex karst aquifer in south Spain (Jarastepar carbonate massif). Over two years, rain and soil water (30 and 60 cm deep) samples were collected simultaneously at an experimental plot along with groundwater from the top of the saturated zone and a base-level spring. Results show that the variation in the concentration of natural soil tracers and the signal of water stable isotopes (δ2H and δ18O) smooth throughout the different compartments of the aquifer, with rapid variations in the unsaturated zone after recharge events and delayed effects in the saturated zone.Funding for open access charge: Universidad de Málaga / CBUA. This research was supported by the project PID2019-111759RB-I00 funded by the Agencia Estatal de Investigación (AEI/https://doi.org/10.13039/501100011033) of the Spanish Government

Características hidroquímicas de humedales salinos andaluces situados en distintos contextos hidrogeológicos

Póster. Comunicación científicaBuena parte de los humedales se encuentran relacionados con acuíferos de su entorno, hasta el punto de que su génesis y funcionamiento hídrico depende, en gran medida, de las aguas subterráneas (Linares, 2008). Por consiguiente, la calidad química de las aguas de los acuíferos determina de forma notable la de los humedales. No obstante, otros procesos hidrológicos, como la recarga superficial y la evaporación, juegan también un papel significativo en la hidroquímica de las lagunas (Custodio, 2001). Por ello, los aspectos hidrológico-hidrogeológicos son imprescindibles para entender el funcionamiento hídrico de los humedales y fundamentar en ellos otro tipo de estudios (ecológicos, botánicos, zoológicos). Con el fin de mejorar el conocimiento existente sobre de la influencia que ejercen los contextos geológico e hidrológico de los humedales sobre la composición química de sus aguas, se han seleccionado 20 lagunas andaluzas, repartidas entre las provincias de Málaga, Córdoba y Jaén, para su caracterización hidroquímica. Dichos humedales están asociadas a dos contextos geológicos distintos: los materiales arcilloso-evaporíticos pertenecientes a los Complejos Caóticos Subbéticos –CCS- (12 humedales) y los sedimentos detríticos aluviales que conforman el Paraje Natural de la Desembocadura del Río Guadalhorce, Málaga (8 humedales). Se han recogido y analizado en total 231 muestras, provenientes de las distintas laguanas, entre septiembre de 2014 y septiembre de 2016. Los análisis realizados incluyen la determinación de la alcalinidad total (HCO3- + CO32-) y de la concentración de iones mayoritarios (Cl-, SO42-, Na+, Ca2+, Mg2+, NO3-) y algunos minoritarios (Br-, K+, NH4+ y Li+). Los resultados obtenidos indican que las facies hidroquímicas predominantes en las aguas de los humedales de interior son las de tipo clorurada-sódica, sulfatada-cálcica y, en algunos casos, mixtas. Ello es debido a la presencia de minerales muy solubles (yeso y halita) en los materiales arcilloso-evaporíticos sobre los que se ubican los humedales, que favorecen la incorporación de Cl-, SO42-, Na+ y Ca2+ a las aguas subterráneas. Por su parte, los humedales costeros presentan aguas de facies clorurada-sódica exclusivamente, así como una mayor proporción de Mg2+ frente a Ca2+, debido a la influencia del Mar Mediterráneo en el acuífero aluvial que los alimenta. Las muestras de agua de las lagunas asociadas a los CCS presentan valores de la relación rCl-/Br- comprendidos entre 250 y 10.400, los cuales aumentan, de forma general, paralelamente a la mineralización. Esto podría atribuirse al aporte de Cl- producido por la disolución de halita (Kloppmann et al., 2001). Así mismo, algunas de estas muestras de agua presentan un enriquecimiento en Br- respecto a la línea teórica de disolución de la halita, debido a la precipitación de NaCl por evaporación (Alcalá y Custodio, 2008). Los valores de rCl-/Br- de las muestras de las lagunas costeras se sitúan entre 600 y 750, muy próximos al valor medio del agua de mar (655; Davis et al., 1998), lo que reflejaría la influencia marina sobre la composición química de las aguas de dichos humedales. Además, el conjunto de lagunas estudiadas ofrece un amplio rango de mineralización (hidrodiversidad), con aguas que contienen desde varias decenas de mg/l de Cl- (dulces) hasta otras que tienen decenas o cientos de miles de mg/l de Cl- (hipersalinas). En este trabajo se pone de manifiesto la notable influencia que ejerce el contexto geológico (geodiversidad) sobre la hidroquímica (hidrodiversidad) de los humedales andaluces, muchos de ellos de gran valor ambiental y que, a su vez, dan lugar a una importante variedad de hábitats. Ello les permite albergar una gran diversidad biológica, entre las que se incluyen especies de avifauna tan emblemáticas como el flamenco rosa (Phoenicopterus roseus), la malvasía cabeciblanca (Oxyura leucocephala) o el águila pescadora (Pandion haliaetus).Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Contexto hidrogeológico y aproximación al balance hídrico de las lagunas Amarga y de los Jarales (Lucena, Córdoba)

La génesis de las lagunas Amarga y de Los Jarales (Lucena, Córdoba) está asociada a la karstificación de los materiales arcilloso-evaporíticos triásicos (Keuper) del Complejo Caótico Subbético (CCS). Con objeto de determinar el grado de relación entre las aguas subterráneas y las lagunas se han efectuado (1) un registro limnimétrico automatizado y un control climático en sus inmediaciones que ha permitido cuantificar las componentes de entrada (precipitación y escorrentía) y salida (evaporación) de los humedales, y (2) campañas de piezometría para caracterizar el sentido de los flujos subterráneos. La morfología de la cubeta de la laguna de Los Jarales se ha precisado a partir de datos LiDAR. Finalmente, se han simulado las evoluciones limnimétricas de ambas lagunas, utilizando diferentes métodos para el cálculo de la escorrentía. Los resultados obtenidos han permitido precisar los balances hídricos de ambos humedales durante varios años secos y constatar que la relación humedal-agua subterránea influye sobre la dinámica de las dos lagunas, aunque en distinto grado. Un control hidrometeorológico más prolongado ayudaría a profundizar en el conocimiento del funcionamiento hídrico de ambas lagunas, lo que facilitaría las tareas de gestión y conservaciónUniversidad de Málaga. Campus de Excelencia Internacional Andalucía Tec

Towards a better understanding of time-lags in karst aquifers by combining hydrological analysis tools and dye tracer tests. Application to a binary karst aquifer in southern Spain

The assessment of the response time of a karst aquifer is an important step towards the development of conceptual models from which tools for water resources planning and management could be applied. The aim of this work is to evaluate the applicability of the joint use of statistical time-lag evaluation and dye tracer tests techniques with a double objective: 1) the development of conceptual models on the hydrogeological functioning that include the duality in the aquifer recharge processes, as well as the particularities of the preferential drainage flowpaths respect to the global response of the aquifers; 2) to establish a reference frame to foresee with enough time in anticipation the potential affections derived from the concentrated recharge to the springs, required in the creation of water quality monitoring networks and early warning systems to water pollution. In the Ubrique karst aquifer (southern Spain), the empirical relationships between the intensity (I) of rainfall events (recharge) and the time-lag (T) observed in the springs that draining the aquifer have been quantified. The establishment of the curve (I-T) constitutes a reliable tool for the prediction of potential affections to the springs (intended for urban supply) derived from recharge events. On the other hand, the comparison of the values drawn in the I-T curve, characteristic of each spring, with those derived from three tracer tests, has allowed further advances in the understanding of the aquifer functioning and the influence of concentrated recharge on the global system behavior to be achieved.This research was supported by the European Project “Karst Aquifer Resources availability and quality in the Mediterranean Area (KARMA)” PRIMA, ANR-18-PRIM-0005. The associated project PCI2019-103675 was funded by the Spanish Research Agency through the scientific program “Programación Conjunta Internacional”. Additionally, it contributes to the project PID2019-111759RB-I00 supported by the Agencia Estatal de Investigación (AEI/https://doi.org/10.13039/501100 011033) of the Spanish Government. Funding for open access charge: University of Malaga / CBU

Considerations about the hydrogeological functioning of the Alta Cadena carbonate aquifer (Málaga province, Spain)

The hydrodinamic and hydrochemical responses of three springs (Villanueva del Rosario, Pita and Parroso) located in the Alta Cadena carbonate aquifer (province of Malaga, South Spain) have been monitored from September 2006 to January 2008. A first interpretation on the hydrogeological functioning and on the karst network development has been performed, which is useful for groundwater protection. Thus, Villanueva del Rosario spring drains a part of the Alta Cadena aquifer more karstified than the catchment area of the other two springs. This means that catchment area of Villanueva del Rosario spring is more vulnerable than the other to the contamination and consequently it needs more strict protection criteri

Monitoring and preliminary analysis of the natural responses recorded in a poorly accessible streambed spring located at a fluviokarstic gorge in Southern Spain

The analysis of natural responses (hydrodynamic, hydrothermal and hydrochemical) of karst springs is a well-established approach to provide insights into the hydrogeological functioning of the aquifers that they drain. However, a suitable monitoring program of these responses are often difficult to launch in poorly accessible streambed springs, due to the mixing between surface water and groundwater, in addition to topographic impediments. This work describes the installation procedure of the measurement equipment and the preliminary hydrogeological dataset collected at the Charco del Moro spring (Southern Spain) during one year. This outlet emerges 5 m below water surface, at the bottom of a partially flooded 20 - 200 m deep and 2 km long gorge, eroded by the Guadiaro River streamflow. It is considered the largest discharge point in the region, draining groundwater from northern nearby carbonate outcrops, although its catchment area is not established yet. Continuous (hourly) monitoring of electrical conductivity, water temperature, turbidity and water level (discharge) reflects a high degree of heterogeneity in the duality of groundwater flow and storage dynamics, which is typical of karst conduit flow systemsUniversidad de Málaga. Campus de Excelencia Internacional Andalucía Tec

222Rn as a natural tracer to investigate recharge and groundwater flow dynamics at three Mediterranean karst systems in Southern Spain.

Comprehensive knowledge of groundwater origin and movement into karst aquifers is crucial to establish the adequate management practices. This is of special interest in areas strongly affected by the impact of climate change, such as the Mediterranean region. This work aims to better understand recharge processes determining groundwater flow in 3 mountainous carbonate aquifers in Southern Spain. To achieve this purpose, spring discharge and electrical conductivity data as well as 222Rn activity were measured and interpreted in karst groundwater. Karst groundwater discharge at the investigated springs varies between 3 and 1400 L/s, while electrical conductivity (EC) values range between 227 and 1929 µS/cm. 222Rn activity data are found between 31-3630 Bq/m3. The temporal evolution of EC, water temperature and 222Rn showed relatively constant values during dry periods in all examined karst springs but abrupt decreases after intense recharge events. A detailed –daily- control during high waters in the Sierra de Ubrique revealed slight increases in 222Rn activity at the beginning of the rising limb of spring discharge. However, circulation of recently infiltrated rainwater through karst conduits (in turbulent flow regimes) and the mixing with old waters provokes a marked dropping in the measured parameters at karst springs.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech