Geodiversidad + Hidrodiversidad = Biodiversidad

Cuevas, lagunas, montañas o desembocaduras esconden en su interior el paso de los diferentes cambios climáticos que ha sufrido la Tierra, una pista fundamental a la hora de entender, de conservar y de gestionar la diversidad de especies y de espacios naturales como Fuente de Piedra o El Torcal

Karst flow system information from shape analysis and numerical modeling of tracer concentration curves

Dye tracing constitute a very valuable tool for investigating the origin of groundwater and delineating flowpaths in karst media, providing direct and quantitative information about the hydraulic properties and solute transport dynamic within a conduit (and/or fracture) dominated system. In this sense, data obtained from 8 single- and multi-injection tracer experiments performed during last years in different carbonate aquifers located in Malaga province (southern Spain) have been re-examined following the numerical solutions provided by a dual process-based approach: advection–dispersion model (ADM) and two-region non-equilibrium model (2RNE). Tracer tests were conducted under different hydrological conditions (high-intermediate-low flow) affecting the aquifers, and the fluorescent substances were injected into sinkholes (5), losing streams (4), karrenfields (1) and dolines (1), while springs commonly served as detection points (manual sampling and eventually field fluorimeters). Flow and transport parameters estimates obtained from the simulation of 13 tracer breakthrough curves (BTCs) provided mixed information on a wide range of hydrogeological behaviors: from well-developed conduit flow paths to flow and storage modalities in a fissured-like systems. The statistical treatment of the analytical and numerical results, jointly to the field observations, has been especially useful for the characterization of the predominant solute transport processes in the studied experimental sites, given the significant deviations that have been eventually found between the shape of the measured and modeled curves (marked skewness, single/multi-pulse geometry, long-tailing effect, etc). These findings will allow for a better understanding of the structure and dynamic of the karst systems investigated and will may help to protect and preserve karst water resources in the region.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

On the value of water quality observations for karst model parameterization

If properly applied, karst hydrological models are a valuable tool for karst water resources management. If they are able to reproduce the relevant flow and storage processes of a karst system, they can be used for prediction of water resources availability when climate or land use are expected to change. A common challenge to apply karst simulation models is the limited availability of observations to identify their model parameters. In this study, we quantify the value of information added to parameter estimation when water quality data (NO3 and SO4) is used in addition to discharge observations to estimate the parameters of a process-based karst simulation model at a test site in Southern Spain. We use a three-step procedure (1) to confine an initial sample of 500,000 model parameter sets, (2) to identify alterations of individual model parameters through the confinement, and (3) to quantify the strength of the confinement for each of the model parameters. The last step allows us to quantify the information content of hydrodynamic and water quality observations for model parameter estimation. Our results show that NO3 provides most information to identify the model parameters controlling soil and epikarst dynamics, while discharge observations provide most information about the recharge area and the groundwater dynamics. SO4 mostly contributes to the identification of recharge processes. Looking at different flow states of the system, we also find that information provided by our observations varies over time.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Hydrogeological model of Mijas mountain aquifers under different climate conditions (Málaga, Spain)

Carbonate aquifers represent an important source of freshwater, both for urban and agricultural uses. This is particularly true in semiarid regions, where intensive pumping has often led to aquifer overexploitation. One example is the Mijas mountain carbonate diffuse flow system (80 km2), located to the SW of the city of Malaga, Spain. From a geolo-gical standpoint, this area consists of Triassic dolomitic and calcareous rocks, which overlay Palaeozoic metapelites. The geological structure is formed by ESE-WNW folds and the me-tapelites anticlinal cores have divided the study area into four aquifer systems. The recharge of Mijas mountain aquifers comes from direct infiltration of rainfall, while pumping is the main discharge. To improve the knowledge of geological and hydrodynamic parameters, and therefore to improve water resources management, a hydrogeological model has been developed with Processing Modflow 8.0.42. Piezometric level and spring flows have been modelled, under steady and transient-flow conditions for a 35-year period. Five future scenarios were simulated for different rainfall and pumping conditions. Outcomes confirm that the water level evolution is determined by the quantity and distribution of rainfall during the hydrological year, with the same pumping rate. The results also suggest that current trends are likely to raise sustainability issues in the future.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Resultados preliminares de la investigación hidrogeológica del acuífero aluvial del río Guadaiza (Marbella, España)

Los acuíferos detríticos costeros pliocuaternarios del sector Marbella – Estepona (provincia de Málaga) constituyen la segunda fuente de abastecimiento de agua en dichos términos municipales, después del embalse de la Concepción. Durante las últimas décadas, los acuíferos han sido objeto de explotación y, dada la cercanía al mar, han sufrido intrusión marina. Este hecho ha conllevado un empeoramiento de la calidad química del agua que impacta de forma negativa en el aprovechamiento del recurso. Con el objetivo de realizar una primera aproximación sobre el funcionamiento hidrogeológico del acuífero aluvial del río Guadaiza, se instalaron –en un piezómetro cercano al cauce del río- dos equipos de registro continuo. Las variables que se controlan son tres: profundidad del nivel piezométrico (cada media hora), temperatura y conductividad eléctrica (con periodicidad horaria). A partir de los datos obtenidos por ambos equipos se ha analizado el comportamiento hidrodinámico e hidroquímico del acuífero frente a eventos pluviométricos de distinta intensidad. En menos de un día desde el inicio de las lluvias se produjeron rápidos ascensos de nivel piezométrico (de más dos metros) y diluciones de hasta 300 μS/cm. La duración de los efectos positivos de la recarga depende, en gran medida, de la distribución de la precipitación. La presencia de infraestructuras de regulación aguas arriba del acuífero disminuye la potencial infiltración de recursos superficiales. Los resultados preliminares obtenidos tienen repercusiones directas en la gestión de los acuíferos y determinan en gran medida su inclusión en sistemas de uso conjunto de recursos hídricos.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Mecanismos de transferencia de flujo subterráneo en un sector acuífero de la Serranía Oriental de Ronda sometido a diferentes condiciones hidroclimáticas

El manantial del Barranco de Palomeras constituye uno de los principales puntos de descarga visible de agua subterránea del acuífero carbonático jurásico de la Sierra de los Merinos (Serranía de Ronda oriental, Málaga). El control hidrogeológico de la surgencia y de tres sondeos, perforados a distintas profundidades y situados a escasos metros de aquella, ha permitido registrar los cambios hidrodinámicos (caudal/nivel piezométrico), de mineralización y de temperatura del agua subterránea producidos en las inmediaciones de la zona de descarga, durante un período hidroclimático altamente variable. Los resultados obtenidos ponen de manifiesto cierta variabilidad de la mineralización y temperatura del agua drenada por el manantial y de la existente en la columna de los sondeos, como consecuencia de episodios de recarga de poca magnitud y/o duración en el tiempo, lo que refleja el drenaje de flujos kársticos de procedencia preferentemente superficial (zona no saturada). En condiciones de elevada recarga, la red de flujo llega a saturarse por completo y se generan limitaciones en el sistema de drenaje, como resultado de la activación de flujos de agua verticales ascendentes, más mineralizados y química y térmicamente homogéneos, que demuestran la contribución predominante de la zona saturada del acuífero (de sectores más profundos y/o alejados) al caudal del manantial del Barranco de Palomeras.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Coupling hydro-geo-chemical and isotopic approaches to assess the main factors controlling karst development in a fissure-dominated carbonate aquifer system (s-Spain)

Sierra Tejeda, Almijara and Albuñuelas mountains comprise a large outcrop (750 km² ca) of Triassic marbles in between of Málaga and Granada provinces in S Spain. They constitute a large entity carbonate aquifer system providing strategic groundwater resources for drinking water supply in sparse urban settlements and crops irrigation. The present research aims to refine the current hydrogeological knowledge of large-scale fissure-dominated carbonate aquifers regarding flow mechanisms and geochemical processes defining observed groundwater quality. To this, a two-year monitoring program of aquifer dynamics have been conducted in three selected discharge points (Fájara, Cijancos and Maro springs) showing characteristic spring responses. A combined approach based on the analysis of spring discharge and time series of selected hydrochemical and isotopic tracers (Na+, Ca+2, Mg+2, TA, TOC, Cl-, SO4-2 and δ13CTDIC) and on the geochemical calculations from the chemical signature of spring waters have been followed. The results indicate that the more bicarbonate enriched waters and the lowest hydrochemical variability of Cijancos spring, practically in all analyzed solutes, denotes a fissure type dominant flow system, while the larger variations in meteoric/soil tracers (Cl- and TOC) observed in Fajara spring chemograph as consequence of rainfall inputs characterize a karst drainage from a better hierarchized fracture-enlarged flow system. Maro spring waters are rich in Na+, Ca+2, Cl- and SO4-2, have higher δ13CTDIC amplitude and the temporal variations of major ions display marked dilutions after rainfall events followed by rapid recoveries of pre-event concentrations, evidence a complex flow system and variable groundwater source contribution. The chemical reactions deduced from the molar ratios of spring water chemistry are commonly CO2 dissolution and calcite dissolution, but also salt evapoconcentration in soil layer and gypsum dissolution in the case of Maro spring.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Geochemical evolution of groundwater in an evaporite karst system: Brujuelo area (Jaén, Spain)

Chemical evolution of groundwater along two main flowpaths was studied in Brujuelo area, an evaporite plateau characterized by the presence of wetlands and drained by hyper-saline springs. Major ions were analyzed, saturation indexes of the main mineral species were computed, and inverse geochemical modeling was performed. Results show a relationship between elevation and water mineralization, indicating that drainage at higher altitude (brackish water) may be associated to gravity-driven flows while lower altitude springs could drain regional groundwater flows (brine water). Modeling results strongly support the hypothesis that most of the selected springs geochemically evolve in a common (S-N) flowpath.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

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

Análisis preliminar de diferentes índices de sequía en el marco de la planificación hidrológica. El caso del sistema de explotación de la Costa del Sol occidental

La gestión del agua en zonas turístico-costeras de clima mediterráneo se presenta como un gran reto del siglo XXI. Se trata de áreas densamente pobladas y con grandes fluctuaciones estacionales en el número de habitantes y, por tanto, en la demanda de agua. La existencia en el subsistema de explotación I-3 (Costa del Sol Occidental) de recursos de agua de distinta procedencia (superficiales, subterráneos, etc.) convierte a este sistema de explotación en un ejemplo para el cálculo de diferentes índices de sequía a partir de distintos tipos de variables (climáticas, hidrogeológicas e hidrológicas). Se han utilizado dos índices, el índice estandarizado de precipitación (SPI) y el índice de estado (Ie). Los resultados obtenidos han variado en función del índice y de la variable analizada. Se ha observado un comportamiento menos oscilante, y por lo tanto más útil a la hora de identificar sequías a medio y largo plazo, en el caso del índice SPI para todas las variables, y del índice Ie aplicado a las series de piezometría y volumen almacenado en el embalse de La Concepción.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech