Origin of flooding water through hydrogeochemical identification, the Buenos Aires plain, Argentina (original) (raw)
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Hydrogeology Journal, 2008
The region known as Pampa Plain, in Argentina, is a vast area characterized by slopes of less than 0.05%. The surface sediment is silty sand, mainly Aeolian, referred to as Pampean Loess, which is a phreatic aquifer unit of utmost importance for the water supply of the region. On account of the slight gradient, hydrogeological analyses using only hydraulic measurements are difficult to perform, often leading to confusing results. Thus, the study presented relies on hydrochemical modeling and isotopic determinations as well. The study area comprises three catchments in the inter-mountainous area corresponding to El Moro, Tamangueyú and Seco creeks, and covering 2,570 km 2 in the province of Buenos Aires. Measurements of piezometric levels and samples of groundwater, surface water and rainwater were carried out between January and March 2005. Major ion results were analyzed by means of hydrochemical graphs and hydrogeochemical modelling using NETPATH. The resulting data show that it is possible to identify local changes in recharge, flow direction and stream/groundwater relation-ship by using hydrochemical and isotopic information, which may become a useful and more precise tool for the study of particularly flat landscapes.
International Journal of Environmental Research, 2011
This paper gives an account of the implementation of geomorphological, hydrogeological, hydrochemical and isotopic techniques to understand groundwater-surface water interactions in a multiple use area, Los Padres-La Brava Corridor (SE of Buenos Aires Province, Argentina). The isophreatic map reveals a regional flow from the SW to NE sector, and allowed us to define the effluent-influent behavior of the permanent wetlands in the area. Hydrochemistry and isotopic analysis confirm this flow system in the unconfined aquifer and the relationships among the different water sources. Obtained data indicate that the recharge to the aquifer is influenced by the natural rainfall input, wetland discharge and the concentration of surface run-off from the range fringes to inter-range depressions. Wetlands in the corridor are considered recharge areas for the aquifer system. Moreover, they contribute to water quality as well as groundwater and stream availability. This study proposes a holistic approach to water resources management recognizing most of the components of the hydrological cycle and its interactions with other natural resources and ecosystems, both aquatic and terrestrial ones. In this sense, the idea of water resources assessment in an integrated way for an efficient management, including wetlands, streams and groundwater, is reinforced in this work.
Water resources in the semi-arid Pampa–Patagonia transitional region of Argentina
Journal of Arid Environments, 2003
The study was carried out in the zone corresponding to the Anzoátegui district (Province of La Pampa, Argentina), covering an area of 1600 km 2 . This zone belongs to the Caldenal or Southern Espinal, an semi-arid region in central Argentina. The annual rainfall is 109/761 mm, but the annual evapotranspiration is as high as 1220 mm, so that the annual runoff is small compared with the annual rainfall. Since shallow ground-water is the principal source of water in the region, the hydrodynamics of the subterranean flow was evaluated and the depth variation of hydrostatic levels in relation to the surface was studied. Water quality was determined by hydrochemical analyses and classified for drinking water for cattle, human consumption and irrigation. It was found to be poor, 60?2% of the study area is affected by saline concentrations exceeds 5?0 dSm À1 . With respect to the ground-water-quality deterioration, reference was made to land use and management systems in the area, where the main economic activity is the cattle breeding, so that the vegetation has been degraded by overgrazing and deforestation for over 100 years.
Key hydrological processes in the Del Azul Creek basin, sub-humid Pampean Plain
Science of The Total Environment, 2020
Groundwater plays an important role in the economic development of the Chaco-Pampean Plain (Argentina), where industry, agriculture and cattle farming are the main economic activities. The 66% of the country's population lives in this area. The low slopes of this region condition the water movement and the occurrence of physical and chemical processes. The aim of this work is to update the hydrological conceptual model of the Del Azul Creek basin (Buenos Aires Province), a sub-humid and continental plain, using environmental tracers. In total, the study was based on the analysis of 201 samples (stable isotopes) and 184 samples (chemical data) including rainwater, surface water and groundwater. The temporal and spatial variation in the isotopic composition of rainfall and the hydrological physical-processes, evaporation, surface water-groundwater interaction and recharge were studied. Isotopic compositions of rainfall revealed a seasonal variation across the basin. Low δ 18 O rainfalls occur during the coldest seasons, while high δ 18 O rainfalls occur during the warmest seasons. The isotopic compositions of rainfall varied only during the cold period in the upper basin. At this time, the lowest δ 18 O rainfall fell in the upper basin, while in the other areas and during the warmer seasons, no differences were observed. Evaporation was a relevant process in the flatter area of the basin, mainly during the warmest seasons. Samples taken from the wetlands and from the lower section of the Del Azul Creek were strongly evaporated. In the first 30 m depth of the aquifer, groundwater reflected the isotopic composition of rainfall from the warmest seasons, thus revealing seasonal preferential recharge and a good hydraulic connection. This study provides direct evidence showing that both evaporation and the surface water-groundwater interaction are processes that play a key role in the control of the isotopic and chemical composition of water.
Isotopes in Environmental and Health Studies, 2020
The objective of this work is to enhance the conceptual hydrogeological model in the Río Cuarto River basin by using isotope and hydrochemical techniques. The precipitation pattern, as reflected in the average values of δ 2 H and δ 18 O in stations located in the plains and in the mountains, showed an isotope depletion from the East to the West, attributed to continental and altitude effects. Groundwater quality is mainly the result of two controlling factors: lithology and flow distances from recharge. The aquifers show fresh calcium/sodium bicarbonate water in the upper and medium basin (coarse fluvial sediments) which evolve to sodium sulphate and chloride waters in the low basin (mainly loess and fine alluvial sediments). The confined aquifer systems in the lower basin (C and D systems) averaged more negative stable isotope values, indicating that groundwater recharged during colder climatic conditions (Pleistocene period). Groundwater dating with 14 C confirmed that groundwater ages range from modern to 45,000 years BP showing that as the water flows towards deeper layers and farther from the mountainous recharge area, groundwater age increases. The confined aquifers can potentially be exploited in order to partly cover different water needs but they should be managed in a sustainable way.
Isotopes in Environmental and Health Studies, 2013
This contribution presents the hydrochemical and isotopic characterisation of the phreatic aquifer located in the Partido de la Costa, province of Buenos Aires, Argentina. In the sand-dune barrier geomorphological environment, groundwater is mainly a low-salinity Ca-HCO 3 and Na-HCO 3-type, being in general suitable for drinking, whereas in the continental plain (silty clay sediments), groundwater is a Na-Cl type with high salinity and unsuitable for human consumption. The general isotopic composition of the area ranges from −6.8 to −4.3 ‰ for δ 18 O and from −39 to −21 ‰ for δ 2 H, showing that rainwater rapidly infiltrates into the sandy substrate and reaches the water table almost without significant modification in its isotopic composition. These analyses, combined with other chemical parameters, made it possible to corroborate that in the eastern area of the phreatic aquifer, there is no contamination from marine salt water.
Environmental Geology, 2008
The main ions were measured seasonally during two years at 13 sampling stations in the Salado River and its main tributaries. The importance of each ion was assessed by standard methods used to examine ionic composition and by multivariate methods. The K-means clustering and Principal Component Analysis were applied to the percentages of the major ions. The concentration of the major cations are in the order Na + > Mg 2+ > Ca 2+ > K + and the major anions, Cl-> SO 4 2-> HCO 3-> CO 3 2-, and the salinity was high (mean TDS 2,691 mg l-1) due to sodium chloride. Using the proportions of the ions was possible to identify seven types of water within the basin related to discharges of different river sub-catchments and from endorheic catchments (in a sand dune region) actually connected with the basin by canals. The chemical composition of the basin is consequence of surface waters receiving salts from groundwater, evaporation and weathering of Post-Pampeano materials, and of anthropogenic impact by diversion between subcatchments for flood control. These results allowed us to test the marked effects on the ionic balance of basin at the base of a diversion management from endorheic catchments characterized by high salinity waters.
River Research and Applications, 2016
The Quequén Grande River (QGR) is a large catchment (10 000 km 2) in the Pampa Plain in Argentina. From November 2004 to April 2013, a hydrochemical and stable isotopes monitoring program was conducted, which included three sampling stations of monthly composite precipitation, weekly samples in two sites along the river and several groundwater samples. A standard data interpretation was initially performed applying standard statistics, Piper diagrams and δ 18 O versus δ 2 H diagrams. The time evolution of the values of δ 18 O in precipitation and streamwater were also determined. The integration of hydrogeochemistry and stable isotopes data indicates the existence of three main components of streamflow: (i) baseflow characterized by electrical conductivity (EC) from 1200 to 1800 μs/cm and an isotope composition quite constant around δ 18 O À5.3‰ and δ 2 H À33.8‰. Water age for groundwater contribution is typically around 30 to 40 years using chlorofluorocarbons; (ii) direct runoff composed of channel interception and overland flow, which is of low EC in the order of 50 to 100 μs/cm, and a highly variable isotopic composition; and (iii) translatory flow (pre-event water that is stored within the subsoil) with an intermediate EC and isotopic composition close to that of the weighted average composition of precipitation. The hydrochemical and stable isotopic data allow the differentiation between baseflow and direct runoff. In addition to this, chlorofluorocarbon dating is a useful tool in assessing the dominance of baseflow in a stream. The data lead to a conceptual model in which an intermediate flow system, with mean residence time (MRT) of around 35 years, discharges into the drainage network. A regional flow system (MRT > 50 years) discharges to the ocean. It is concluded that in this large plain catchment streamflow separation, only two components can be applied in: (i) short storm precipitation events having a high sampling frequency and (ii) during long dry periods when pre-event soil water is not released.
Hydrologic response of the drainage basins that intersect Las Grutas town, Argentina
Investigaciones …, 2011
The town of Las Grutas, in a semiarid region on the north west coast of San Matías Gulf (Argentina), is intersected by two drainage basins that are activated immediately after intense rainfall events. These events generate flows capable of producing local flooding, such as the flood of April 2004. The purpose of this study is to establish the hydrologic behavior of these geoforms and the manner in which the land use interacts with them. The lack of hydrometric records necessitates the explanation and prediction of hydrologic responses through empirical approaches such as fluvial morphometry and the USDA Soil Conservation Service curve number (1972), supported by Geographical Information System technology. The study area has characteristics that favor the concentration of runoff into streams during extreme events. First-order segments play an important role in the hydrologic response, showing great potential to receive surface runoff. The effect of urbanization produces an additional runoff of 17.3% and 2.1% in the respective basins. A potential increase in the number of these extreme events in the future due to climate change may lead to more disturbances in the urbanized area. The results of the present study will contribute to the implementation of measures to mitigate the consequences of floods.
Hydrogeology and hidrogeochemical modeling in phreatic aquifer of NE Mendoza, Argentina
Journal of Iberian Geology, 2014
The objectives of this study are to develop a conceptual hydrogeological model and evaluate groundwater hydrochemical characteristics of the aquifer in the Guanacache Travesía, in the central Monte desert of Mendoza (Argentina). The region has been granted to aboriginal communities for communal use and is experiencing economic development. The area has limited surface water resources and relies on groundwater for economic activities, and in many cases, for human consumption. There are no hydrogeochemical studies on the quality of this water as drinking water or its suitability for agriculture and raising livestock. The present study provides information on water quality and availability in the northeast of Mendoza Province. It includes a detailed review of relevant bibliography, including scattered and unpublished studies with geological and geomorphological data. It also includes water level measurements, a definition of water flow direction and hydrochemical analyses, including some trace elements and isotopic data. The hydrogeological model shows a discharge area characterized by vertical upward flows, evident by thermal waters, lakes, salt deposits and the presence of reduced arsenic in some boreholes. The dominance of fine sediments, low relief, scarce local precipitation, low recharge from precipitation, and low groundwater velocities result in long residence times for groundwater and poor renovation (with remote recharge area). Groundwater has high salt content and hardness, as well as trace elements such as fluoride and arsenic. Localized patches of low salinity waters are found along paleochannels. The isotopic signature of these waters indicates distant precipitation from the mountains, which could also have recharged the aquifer in historic times. In addition to the important geologic controls on surface and groundwater flows, human activities affect local conditions of the aquifer near livestock gathering areas, increasing nitrate concentrations and the proportion of As(III) relative to As(V).