Relaciones hidrogeológicas y medioambientales entre el Mar Mediterráneo, el Saladar y el acuífero de Agua Amarga (provincia de Alicante)

Abstract

[SPA] El Saladar de Agua Amarga, situado al sur de Alicante, se encuentra sobre un acuífero costero del mismo nombre que en las últimas décadas ha sido escenario de dos intervenciones antrópicas sucesivas: la actividad de una industria salinera y la explotación para el abastecimiento de las desaladoras de Alicante I y II. Estas intervenciones han condicionado sensiblemente tanto la calidad química de las aguas subterráneas, cuya elevada salinidad es consecuencia de las antiguas salinas, como el régimen de flujo, merced a los conos de bombeo de los pozos de extracción de las desaladoras. Además, el saladar está ligado a una zona húmeda de interés ecológico. Con objeto de realizar un seguimiento piezométrico y de calidad química de las aguas del acuífero, la Mancomunidad de los Canales del Taibilla (organismo gestor de la explotación de las desaladoras), en colaboración con la UPCT, diseñó una red de control sobre el saladar y su entorno. Desde mayo de 2008, se realiza un registro mensual de piezometría y conductividad eléctrica, proporcionando los datos tratados en el presente trabajo. En esta Tesis Doctoral se investiga el régimen hidrodinámico e hidroquímico del acuífero y se desarrolla un modelo conceptual de funcionamiento. En primer lugar se caracteriza el entorno de la zona de estudio en relación con su climatología, geología, geomorfología e hidrogeología, utilizando la información bibliográfica existente, y se describen las obras de captación de las desaladoras. A continuación, a partir de los informes de la etapa de investigación previa a la construcción de las desaladoras y de la información geológica de nuevas campañas de campo, se caracteriza el acuífero costero de Agua Amarga: tipo de acuífero, litología, parámetros hidráulicos, espesor, extensión, etc. Para valorar las respuestas del acuífero frente a los registros de lluvias, extracciones y vertidos de agua del mar sobre el saladar, se ha integrado esta información con los datos de las campañas mensuales de control de piezometría y calidad química. Paralelamente, con el objeto de conocer los procesos de mezcla y el origen de las aguas, se han efectuado análisis químicos e isotópicos a muestras de aguas meteóricas y subterráneas en distintos puntos. Con todo ello se ha elaborado un modelo conceptual de funcionamiento del acuífero y un balance hídrico. Como apoyo a este estudio se realiza un modelo 3-D de flujo y transporte con SEAWAT con la pretensión de explicar e interpretar cualitativa, y en menor medida cuantitativamente, los procesos que tienen lugar en el acuífero, ya sean motivados por intervenciones antrópicas o naturales. También se incluye un estudio de la caracterización física de escenarios 2-D de intrusión marina en presencia de saladares cercanos. Por último, se describen los valores ecológicos del humedal y se evalúa el efecto de la actividad de las desaladoras y del plan de recuperación con vertidos de agua de mar sobre la piezometría y salinidad de las aguas, valorando la posibilidad de implementar estas medidas en otros escenarios semejantes. [ENG] he Saladar of Agua Amarga, located at the south of Alicante province, lays over the coastal aquifer of its name which in the last decades has been subjected to two successive anthropogenic actuations: the exploitation of a salt marsh at its surface and the water supply for the desalination plants of Alicante I and II. These actuations have mostly influenced both by the chemical quality of the underground water, whose high grade of salinity is a direct consequence of the ancient salt marsh, and the flow regime, due to the pumping cone of the extraction wells of plants. In addition, the Saladar of Agua Amarga is linked to a wetland zone of ecological interest. In order to realize the study of the piezometric changes as well as the chemical quality of the ground water caused by the anthropogenic actuations, the ‘Mancomunidad de los Canales del Taibilla’ (responsible of the exploitation of the plants), in collaboration with the UPCT, designed a piezometric network over the Saladar and its surroundings. From May 2008, is carried out a monthly lecture of piezometry and electric conductivity to provide the treated in this work. In this Doctoral Thesis it is investigated the hydro-dynamic and hydro-chemical regimes of the Agua Amarga´s aquifer developing a performance conceptual model. Firstly, the study area is characterized in relation to its climatology, geology, geomorphology and hydrogeology, by using the background (bibliography) information; the facilities of the desalination plants are also described. Next, from the studies of both the researching made before the installation of the plants and the geological data coming from the new field campaigns, the coastal Agua Amarga aquifer is characterized: sort of aquifer, lithology, hydraulic parameters, thickness, surface extension, etc. To assess the behavior of the aquifer as regards of rainfalls, water catchments for the plants and seawater pouring over the saladar, this information has been integrated in conjunction to the data coming from the monthly campaigns of the control of piezometry and water quality. In parallel, in order to know the mixing processes and the origin of the water, chemical and isotope analysis were carried out on samples of both meteoric and underground water taken at different locations. All the results were used to elaborate a conceptual performance model of the aquifer and a water balance. As an added support of this study a 3-D fluid-flow and solute-transport model has been designed and run in SEAWAT in order to provide a qualitative, and in less degree quantitative, explanation for the processes that emerges in the aquifer, either due to the anthropogenic or natural actuations. Also, the physical characterization of 2-D, marine intrusion with salt flats, scenarios are presented. Finally, ecological values of the wetland are described, evaluating the effect of the salt marsh and the plan of wetland restoration (based on a program of seawater pouring) in the piezometry and salinity of the water, studying the possibility of applied the program to other scenarios.

[ENG] The Saladar of Agua Amarga, located at the south of Alicante province, lays over the coastal aquifer of its name which in the last decades has been subjected to two successive anthropogenic actuations: the exploitation of a salt marsh at its surface and the water supply for the desalination plants of Alicante I and II. These actuations have mostly influenced both by the chemical quality of the underground water, whose high grade of salinity is a direct consequence of the ancient salt marsh, and the flow regime, due to the pumping cone of the extraction wells of plants. In addition, the Saladar of Agua Amarga is linked to a wetland zone of ecological interest. In order to realize the study of the piezometric changes as well as the chemical quality of the ground water caused by the anthropogenic actuations, the ‘Mancomunidad de los Canales del Taibilla’ (responsible of the exploitation of the plants), in collaboration with the UPCT, designed a piezometric network over the Saladar and its surroundings. From May 2008, is carried out a monthly lecture of piezometry and electric conductivity to provide the treated in this work. In this Doctoral Thesis it is investigated the hydro-dynamic and hydro-chemical regimes of the Agua Amarga´s aquifer developing a performance conceptual model. Firstly, the study area is characterized in relation to its climatology, geology, geomorphology and hydrogeology, by using the background (bibliography) information; the facilities of the desalination plants are also described. Next, from the studies of both the researching made before the installation of the plants and the geological data coming from the new field campaigns, the coastal Agua Amarga aquifer is characterized: sort of aquifer, lithology, hydraulic parameters, thickness, surface extension, etc. To assess the behavior of the aquifer as regards of rainfalls, water catchments for the plants and seawater pouring over the saladar, this information has been integrated in conjunction to the data coming from the monthly campaigns of the control of piezometry and water quality. In parallel, in order to know the mixing processes and the origin of the water, chemical and isotope analysis were carried out on samples of both meteoric and underground water taken at different locations. All the results were used to elaborate a conceptual performance model of the aquifer and a water balance. As an added support of this study a 3-D fluid-flow and solute-transport model has been designed and run in SEAWAT in order to provide a qualitative, and in less degree quantitative, explanation for the processes that emerges in the aquifer, either due to the anthropogenic or natural actuations. Also, the physical characterization of 2-D, marine intrusion with salt flats, scenarios are presented. Finally, ecological values of the wetland are described, evaluating the effect of the salt marsh and the plan of wetland restoration (based on a program of seawater pouring) in the piezometry and salinity of the water, studying the possibility of applied the program to other scenarios.