Identification of a Holocene aquifer–lagoon system using hydrogeochemical data (original) (raw)
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Environmental Geology, 1997
The coastal aquifer of Oropesa is affected by salinization processes undoubtedly associated with intense groundwater exploitation for agriculture supply. The aquifer corresponds geologically to a tectonic depression with Plioquaternary fill. Hydrogeologically, this aquifer is detrital, with intergranular porosity, which receives substantial recharge from adjacent Mesozoic aquifers. Contact with the sea, in addition to the presence of cultivated soil requiring extreme exploitation of groundwater, frequently give rise to processes of seawater intrusion. The present research is an attempt to understand the saltwater intrusion in this aquifer, using hydrochemical analyses of the behavior of certain minor ions that could help in the characterization process. In the case of the Oropesa sector, groundwater salinization does not appear to be attributable solely to the intrusion of seawater, but there are also anomalies related largely to the geology of the sector and its surroundings, the type of recharge, the hydrodynamic conditions in the specific area, etc.
Environ Earth Sci, 1997
The coastal aquifer of Oropesa is affected by salinization processes undoubtedly associated with intense groundwater exploitation for agriculture supply. The aquifer corresponds geologically to a tectonic depression with Plioquaternary fill. Hydrogeologically, this aquifer is detrital, with intergranular porosity, which receives substantial recharge from adjacent Mesozoic aquifers. Contact with the sea, in addition to the presence of cultivated soil requiring extreme exploitation of groundwater, frequently give rise to processes of seawater intrusion. The present research is an attempt to understand the saltwater intrusion in this aquifer, using hydrochemical analyses of the behavior of certain minor ions that could help in the characterization process. In the case of the Oropesa sector, groundwater salinization does not appear to be attributable solely to the intrusion of seawater, but there are also anomalies related largely to the geology of the sector and its surroundings, the type of recharge, the hydrodynamic conditions in the specific area, etc.
Ambio, 2008
The Aguadulce aquifer unit in southeastern Spain is a complex hydrogeological system because of the varied lithology of the aquifer strata and the variability of the processes that can take place within the unit. Factorial analysis of the data allowed the number of variables to be reduced to 3 factors, which were found to be related to such physico-chemical processes as marine intrusion and leaching of saline deposits. Variographic analysis was applied to these factors, culminating in a study of spatial distribution using ordinary kriging. Mapping of the factors allowed rapid differentiation of some of the processes that affect the waters of the Gador carbonate aquifer within the Aguadulce unit, without the need to recur to purely hydrogeochemical techniques. The results indicate the existence of several factors related to salinity: marine intrusion, paleowaters, and/or leaching of marls and evaporitic deposits. The techniques employed are effective, and the results conform to those obtained using hydrogeochemical methods (vertical records of conductivity and temperature, ion ratios, and others). The findings of this study confirm that the application of such analytical methods can provide a useful assessment of factors affecting groundwater composition.
Water
The aquifers of the Spanish Mediterranean coast are generally subjected to intense exploitation to meet the growing water supply demands. The result of the exploitation is salinization due to the marine saltwater intrusion, causing a deterioration in the quality of the water pumped, limiting its use for community needs, and not always being well delimited. To prevent deterioration, a groundwater control network usually allows precise knowledge of the areas affected by saltwater intrusion but not the extent of the saline plumes. Moreover, the characterization of aquifer systems requires a model that defines the geometry of aquifer formations. For this objective, we integrated hydrogeological, hydrogeochemical, and electrical resistivity subsoil data to establish a hydrogeological model of the coastal aquifer of Torredembarra (Tarragona, NE Spain). In this research, we have carried out a regional and local-scale study of the aquifer system to define the areas prone to being affected b...
Groundwater dependence of coastal lagoons: The case of La Pletera salt marshes (NE Catalonia)
Journal of Hydrology, 2017
Coastal wetlands are among the most productive ecosystems of the world, playing an important role in coastal defense and wildlife conservation. These ecosystems, however, are usually affected by human activities, which may cause a loss and degradation of their ecological status, a decline of their biodiversity, an alteration of their ecological functioning, and a limitation of their ecosystem services. La Pletera salt marshes (NE Spain) are located in a region mainly dominated by agriculture and tourism activities. Part of these wetlands and lagoons has been affected by an incomplete construction of an urban development and in this moment is the focus of a Life + project, whose aim is to restore this protected area. Several studies have analyzed the role of hydrological regime in nutrients, phytoplankton and zooplankton in this area, however, the role of groundwater was never considered as a relevant factor in the lagoon dynamics, and its influence is still unknown. In this study, the hydrogeological dynamics in La Pletera salt marshes has been analyzed, as a basis to set sustainable management guidelines for this area. In order to determine their dependence on groundwater resources, monthly hydrochemical (with major ions and nutrients) and isotopic (d 18 O H2O and dD) campaigns have been conducted, from November 2014 to October 2015. In particular, groundwater from six wells, surface water from two nearby streams and three permanent lagoons, and sea water was considered in these surveys. Taking into account the meteorological data and the water levels in the lagoons, the General Lake Model has been conducted to determine, not only evaporation and rainfall occurring in the lagoons, but also the total inflows and outflows. In addition, the Gonfiantini isotopic model, together with equilibrium chemical-speciation/mass transfer models, has been used to analyze the evaporation and the physicochemical processes affecting the lagoons. Results show that during the dry season groundwater inputs may account for 15-80% of the water in La Pletera lagoons. Besides, water salinity depends on two main processes: 1) mixing of fresh and sea water occurring within the lagoons or in the aquifer; and 2) evaporation. According to the obtained results, the goal of preserving La Pletera lagoons and their salinity conditions implies maintaining groundwater fluxes towards the ocean, and also the hydraulic connectivity of these lagoons with the aquifer.
The Science of the total environment, 2015
Salinization of water bodies represents a significant risk in water systems. The salinization of waters in a small irrigated hydrological basin is studied herein through an integrated hydrogeochemical study including multivariate statistical analyses and geochemical modeling. The study zone has two well differentiated geologic materials: (i) Quaternary sediments of low salinity and high permeability and (ii) Tertiary sediments of high salinity and very low permeability. In this work, soil samples were collected and leaching experiments conducted on them in the laboratory. In addition, water samples were collected from precipitation, irrigation, groundwater, spring and surface waters. The waters show an increase in salinity from precipitation and irrigation water to ground- and, finally, surface water. The enrichment in salinity is related to the dissolution of soluble mineral present mainly in the Tertiary materials. Cation exchange, precipitation of calcite and, probably, incongrue...
Vegetation History and Archaeobotany, 2008
The palaeoenvironment of a former coastal lagoon in the south eastern Iberian Peninsula (San Rafael, Almeria, Spain) were inferred from one core analyzed for particulate organic matter content (POM) together with its C/N, d 13 C, d 15 N to depict the biogeochemical record from the Late Glacial to the Holocene. The results, complemented by previously reported pollen assemblages, indicate the appearance of a freshwater lagoon at 7300 B.P. (uncalibrated 14 C age), its salinization at 6200 B.P. and its disappearance at 4400 B.P. The period of existence of the lagoon coincided with a period of wetter conditions as inferred from terrestrial vegetation. The lagoon's salinization was not related to a decrease in precipitation but to a stronger maritime influence since there were no parallel changes in terrestrial vegetation. Salinization caused an increase in d 13 C, associated with a higher relative presence of C 4 plants, and an increase in d 15 N, due to a decrease in plant N demand. The late period of the lagoon, from about 5100 to 4400 B.P., shows a progressive drying and salinization not detected in isotopes but reflected in a decrease in POM, and in the pollen records. Increases in d 15 N were related to increases in salinity within the lagoon, and are indicative of a more open N cycle, because the absence of changes in terrestrial vegetation rules out changes in the catchment area as the cause for changes in d 15 N.
Water Resources Management X, 2019
The Manglaralto aquifer is located at the north of the province of Santa Elena, Ecuador, its importance is based on the source of supply for the sector. The objective of this work is to characterize the waters of this hydrogeological system by means of hydrochemical techniques (Piper and Stiff diagrams) and their correlation with the geology of the area, as well as the determination of marine intrusion. The methodology used is based on the concentrations of the major ions, which have been obtained by the water-rock interaction, where the geological analysis helps to understand the conceptual hydrogeological model. The obtained results indicate that there are two groups of waters: in the part closest to the interior of the basin with facies mainly bicarbonate and calcium-sodium, while nearest the sea shows markedly calcified calcium facies, and the existence of marine intrusion in the well closest to the coastline.
In Córdoba province (Argentina), people use groundwater from Confined Aquifers Systems (CASs) for different activities. Therefore, it is necessary to carry out comprehensive studies for the planning of a more sustainable use considering that groundwater renewal times can be of several thousands of years. The objective of this research is to evaluate geochemical and isotopic features of groundwater from a confined aquifer system made up by marine sediments in the central Pampean plain (Argentina). This CAS is multilayered and formed by thin (5 m) sand-pebble lenses of variable extension and clay deposits, linked to the Neogene period. These layers are situated at different depths (between 230-300 m) and are represented by fossiliferous sands interbedded with very thick greenish clay sediments. The marine CAS is characterized by fresh-brackish groundwater that evolves from bicarbonate to sulfate sodium type in the flow direction. The interpretations made from 2 H, 18 O and 3 H results...
Journal of Hydrology, 2009
The coastal plain bordering the southern Venice Lagoon is a reclaimed lowland characterized by high subsidence rate, and ground level and water-table depth below sea level. In this agricultural region, where the surface hydrologic network is entirely artificially controlled by irrigation/drainage canals, salinization problems have long been encountered in soils and groundwaters. Here we use isotopic and geochemical tracers to improve our understanding of the origin of salinization and mineralization of the semi-confined aquifer (0-40 m), and the freshwater inputs to this hydrological system. Water samples have been collected at different seasons in the coastal Adriatic Sea, lagoon, rivers and irrigation canals, as well as in the semi-confined aquifer at depths between 12 and 35 m (14 boreholes), and in the first confined aquifer (three boreholes drilled between 40 and 80 m depth). Stable isotopes (d 18 O and dD) and conductivity profiles show that direct saline intrusion from the sea or the lagoon is observed only in a restricted coastal strip, while brackish groundwaters are found over the entire topographic and piezometric depression in the centre of the study area. Fresh groundwaters are found only in the most western zone. The sharp isotopic contrast between the western and central regions suggests disconnected hydrological circulations between these two parts of the shallow aquifer. The border between these two regions also corresponds to the limits of the most strongly subsiding zone.