Guarani Aquifer Research Articles

The Ajuricaba Basin Creek chemical signature of water resources: Geological sources and anthropogenic contributions

The Ajuricaba Basin Creek is located west of the Parana State, it is part of the Parana 3 Hydrographic Basin and it is located at southwest of the Marechal Candido Rondon county. Its area of around 18 km2 is manly used for agricultural purposes. The basin is part of the Serra Geral Aquifer System (SGAS), which comprises basic volcanic rocks of the Serra Geral Group. The main objectives of this study are the characterization of the hydrogeochemical environments and the understanding of the dissolved elements sources, both geological and human, in order to create a water circulation model of the basin. Two field campaigns, in August and November 2019, were done to collect water samples from surface waters (SW), phreatic aquifer (PA) and fractured aquifer (FA). During the 2019 field campaigns, the temperature, pH, total dissolved solids (TDS) and electrical conductivity (EC) were measured on site. Physicochemical parameters (SiO2, HCO3−, CO3−2, Cl−, F−, PO4−3, SO4−2, NO3−, NO2−, Ca+2, Mg+2, Na+, K+, Fe total, Mn+2, Nb, S, V, Zn, Al, Sr, Ba, P, Ti) of the collected samples were analysed. Preexisting data from December 2010 was also used to observe historical changes in water quality through time. Based on this data, statistical (univariate and correlation) and hydrochemical analysis were conducted in order to characterize the hydrogeochemical environments and surface and groundwater flows in the basin. Historical analysis revealed that SW and PA samples have the most significant impacts on water quality with double the median concentration of NO3− and three to nine times the concentration of Cl−. Hydrochemical analysis showed that SW have higher concentrations of HCO3−, Cl−, NO3−, Ca+2, Mg+2, Al, Sr, Ba and Fe, high TDS and neutral to acid pH. PA has the lowest TDS and acid pH and its main ions are HCO3−, NO3−, Ca+2 and Mg+2. In addition, FA was divided in: FA (Ca+2) with HCO3−, Ca+2 and Mg+2 as main ions, neutral pH and low TDS and FA (Na+) with CO3−2, HCO3−, SO4−2, Na+, V, Nb and P as main ions, basic pH and high TDS. SW has a similar pattern to PA and FA (Ca+2) indicating that the rivers are discharge zones for both aquifers. FA (Ca+2) has a similar hydrochemical signature to SGAS, confirming it origins. In opposition, the FA (Na+) aquifer hydrochemical signature differs from the SGAS and, in fact, is more similar to the one of the confined Guarani Aquifer System (GAS), suggesting a higher residence time. Fa (Na+) waters have higher TDS and basic pH, indicating a higher residence time and depth associated with the ascension of even deeper flows from GAS towards the basin. In addition to the hydrochemical model, this research also highlights the potential of the multielement-hydrochemistry to understand the relations between surface and groundwater resources contributing for the management of water resources in watersheds.

Baseline of the outcropping Guarani Aquifer System in Rivera and Tacuarembó, Uruguay: Piezometry and Vulnerability

The piezometric, water table and vulnerability baseline of the outcropping Guaraní Aquifer System (GAS) in the departments of Rivera and Tacuarembó (Uruguay) is presented. The flow network and chemical composition are essential to understanding underground dynamics and identifying recharge and discharge zones, preferential flow directions, and determining hydraulic gradients. It is essential to analyze its evolution in time and space from the baseline, for the management and protection of the resource. Vulnerability was determined by applying the GOD and EKv methods, obtaining similar results, with areas of high and moderate vulnerability in most of the studied area. The risk of groundwater contamination was determined using the method of Foster & Hirata(34), obtaining high risk for potentially polluting loads from lack of sanitation, solid household waste, irregular settlements, and gas stations, in areas of moderate and high vulnerability. Industrial and mining activity and a cemetery represent a moderate risk in most cases. Having maps of vulnerability and risk of groundwater contamination is essential to identify the most vulnerable areas and implement detailed study, control, and protection tools aimed at conserving and mitigating impacts on GAS.

Hydrogeochemical, Geophysical and Geological Assessment of the Recharge Zone of Guarani Aquifer System in Alegrete, southern Brazil

The state of Rio Grande do Sul has a huge part of the Guarani Aquifer, having a recharge area in its central and western region and, therefore, this investigation was focused on the city of Alegrete. There is no annual plan for water resources in the state and, hence, it is required to evaluate the hydrogeochemical, geophysical and geological characteristics where the aquifer has its recharge regions. Thus, some data were acquired, having chemical analysis of the water in different wells (mostly in rural areas) and refraction seismic and geoelectrical surveys. In addition, the geological information was obtained from the public database SIAGAS (Sistema de Informações de Águas Subterrâneas – ground water information system). Then, different maps of chemical parameters and a Piper diagram were made. Moreover, the refraction seismic and geoelectrical data were processed and interpreted, concatenating these results with the geological data obtained from the SIAGAS wells, mapping the different formations and static levels of the aquifer. A high concentration of lead, chromium and cadmium along with phosphate was found. Additionally, by means of geophysical surveys, a line was pointed out as a possible aquifer, which could be used for human, agropastoral or industrial activities after treatments of altered values.

Geophysical and geological surveys to understand the hydrogeological behavior in an outcrop area of the Guarani Aquifer System, in Brazil

In some Brazilian states, after the long period of drought in the years 2014 to 2015, the issue of water crises became the focus of several studies. Some of these studies propose the use of groundwater to avoid water crises. However, many of these do not understand or ignore the hydrological processes of aquifer recharge and discharge. Understanding the recharge and discharge processes is essential to prevent problems related to aquifers and better understand the exchange relationships between surface and underground reservoirs. Geophysical applications are used to study these hydrological processes of recharge and discharge, however there is a deficit regarding the use of the Electrorestivity method in this type of study. The present work delimited an area close to the escarpment of the Basaltic Cuesta front in the municipality of Ipeúna (SP). The objectives were to understand the recharge and discharge processes using the Electrical Resistivity Tomography (ERT) and a stratigraphic survey. The chosen area is in an outcrop area of the Guarani Aquifer System (GAS), a place known to be important in the recharge of this transboundary aquifer. The stratigraphic survey was carried out by walking along the access road to the study area. In the geophysical survey, 10 parallel lines of electrical resistivity tomography (ERT) were performed in Schlumberger array. The measured resistivity values ranged between 5000 Ω m and 20 Ω m. Data collected in the field were processed and represented in two-dimensional and three-dimensional logarithmic models. Through the correlation between stratigraphy and 2D models, it was possible to locate the porous and fractured aquifers, as well as to relate the resistivity values with the rocks present in the area. The 3D model provided a better visualization of the electrical resistivity values at different depths in the study area. In this way, it was possible to delimit the presence of water in the geological framework. The presence of water inside a large sandstone lens flowing towards the Cuesta front was identified. The geophysical and stratigraphy surveys provided information for the generation of a geological framework model, its relationship with groundwater flow and hydrological processes. The work also reduces the gap of geophysical studies in Guarani Aquifer System and the use of electrical resistivity tomography to understand the hydrological processes of aquifers.

Hydrogeochemical analysis, geophysical assessment and geological mapping of the recharge zone of the Guarani Aquifer system in Santa Cruz do Sul, Brazil

A large part of the Guarani Aquifer is in the state of Rio Grande do Sul (southern Brazil). Aquifer?s recharge area is in the central and western regions of the state. So, this work was focused on the municipality of Santa Cruz do Sul. Because there is no water resources plan in the state by 2022, the hydrogeochemical, geophysical properties, and geological characteristics of the aquifer recharge region were evaluated. Field data were gathered, including chemical analysis of water in different wells and geophysical surveys in refraction seismic and geoelectrical methods. In addition, geological information was obtained from the Groundwater Information System (SIAGAS) public database. The different chemical parameters were mapped to perceive some elements? concentrations in Santa Cruz do Sul according to the SIAGAS data. In addition, the seismic refraction data and geoelectric method were processed and interpreted, concatenating all these results with the geology obtained from SIAGAS wells. The existing formations and the static level of the Guarani Aquifer were mapped using geological data. A high concentration of lead in the region which is a possible aquifer was found using geophysical methods. If located in this area aquifer could be used for human, agropastoral, or industrial after treatments.

Identificação da interação rio-aquífero, por meio de gradientes de temperatura, em área de afloramento do Aquífero Guarani

ABSTRACT The use of temperature as a natural tracer in hydrology is noticed since the 1960s. In recent years, there has been a revival of the use of this physical property in the investigation of water cycle. The main reasons are the cost reduction of temperature measurements and the development of distributed temperature sensing. Here, we present a study of the groundwater-surface water interaction in the Onça Creek Watershed (Guarani Aquifer System outcrop) using stream discharge data and temperature as a natural tracer. Two Parshall flumes were installed 1.2 km apart to quantify stream discharge and determine groundwater contribution. We used an optic fiber cable to identify interaction locations and a probe with thermistors to measure the vertical temperature gradient and estimate flux rates. The results show a discharge difference of ~250 m3.h-1 between both flumes, which we interpret as baseflow contribution. The distributed temperature sensing allowed the identification of regions with gaining behavior. Discharge rates between 200 and 300 mm.day-1 were determined from vertical temperature measurements, which agrees with the streamflow data. The study demonstrated that temperature is attractive as natural tracer in tropical conditions, where the groundwater temperature is higher than the surface water temperature, especially during the winter.

Reply to comment by Haag et al. on “Resurfaced paleodunes from the Botucatu erg amid Cretaceous Paraná volcanics” by Hartmann and Cerva-Alves (2021)

We reported several scientific discoveries, implicitly recognized by the commenters: Fronteira Oeste Rift; description of a unique, forgotten 15,000 km2 area in Brazil that displays the contact of a large Cretaceous paleoerg with a large continental basaltic province; Catalán andesite covering most of the active erg; abundant evidence of hydrothermalism and vapor explosion from the Guarani Aquifer into and over overlying seal rocks; minor ergs not observed above the first lava flows; shape and structure of numerous barchan and seif paleodunes indicate more variable wind directions than previously reported. We used the methodology required to describe the processes. Cerro do Jarau is a compound paleodune (barchan and seif). We acknowledge the qualified comments made by the commenters, but our main evaluation remains unmodified. Continued studies will lead to significant contributions to the understanding of this major eolian-basaltic province in a unique relationship in the continents.

Quantification of Carbon Cycling in a Large Aquifer Using Reactive Transport Modelling

Continental scale aquifers can store significant amounts of carbon as a result of immense water volumes, substantial concentrations of dissolved inorganic carbon (DIC) and its reactions with a matrix, thus contributing the global carbon storage and cycle. However, concentration of dissolved solutes may vary significantly over distances, which causes interpretative challenges and difficulties in process quantification. This occurs in the Guarani Aquifer System in South America, which is a subject of extensive research due to a significant strategic role in water supply. Dissolved CO2is expected to dissociate and undergo reactions with aluminosilicate minerals, but it is unknown how much DIC may get immobilised in the aquifer. To quantify the processes, we performed reactive transport modelling which combines hydrological and geochemical information followed by global sensitivity analysis. We show that more than a half of the infiltrated CO2may be consistently precipitated as CaCO3. The DIC concentrations across the aquifer depend primarily on the input carbon concentrations and the plagioclase hydrolysis rate, while other parameters including hydraulic conductivity, recharge rate and mineral stability are of the minor importance. We present how advanced modelling techniques may be used to interpret and quantify processes controlling water quality in continental scale groundwater systems.

Disposal of pharmaceuticals wastes by the population of an outcrop area of the Guarani Aquifer System in Southern Brazil

Pharmaceutical waste is considered emerging pollutant that can contaminate water sources and underground water, besides is serious problem for waste management in Brazil. The objective of this study was to evaluate the pharmaceutical consumption for human use and the way expired and unused medicines are disposed by the population. The study was carried out in two neighborhoods of the Lages, under outcrop of the Guarani Aquifer, in southern Brazil. In this descriptive and quantitative study, data collection occurred between August and October of 2018 via a questionnaire completed by 309 participants. The questions addressed about sociodemographic data, information on the medicine consumption, disposal of pharmaceuticals residue and about the basic sanitation in the neighborhood. The pharmaceuticals class most used were anti-hypertension and diuretics, indicating an elevated occurrence of non-transmittable chronic illnesses. About 68% of participants stated that there are leftovers of medications after medical treatment and 70.2% that there is expired medication at household. The disposal of leftover and expired pharmaceutical was in domestic waste, followed by discharged into domestic sewage. Only a small percentage (<15%) of the participants adequately dispose of their medication waste. The inadequate disposal of household pharmaceutical in the study area can result in contamination by chemical substances of the Guarani Aquifer and superficial waters.

Spatial targeting approach for a payment for ecosystem services scheme in a peri-urban wellhead area in southeastern Brazil

In recent years, payments for ecosystem services (PES) have emerged as a form of financing for the conservation of natural resources, compensating landowners that generate positive environmental externalities. For the PES design process, the spatial targeting approach for identifying priority areas aiming at the environmental recovery and preservation is essential for the efficient allocation of limited financial resources. In this sense, the present work aims to spatially identify priority areas for the implementation of PES schemes, with emphasis on the conservation of water resources, using as case study the Feijão River watershed (FRW), the primary water source for the city of São Carlos-SP, Brazil. For such, we performed a multicriteria evaluation in geographic information system (GIS) environment for mapping priority areas for forest restoration based on relevant criteria for the provision of hydrological services. We then cross-referenced the resulted information plan with estimated opportunity costs for compensating landowners in order to identify higher restoration priorities associated with low cost sites for PES implementation. The results show that 25.6% of the eligible areas have very high priority to forest restoration and are located mainly along the Feijão River watercourse, in direct recharge areas of the Guarani Aquifer System and with predominance of pasture and sugarcane uses, the main driving forces of erosion processes in the watershed. Among the agricultural activities, livestock presented the lowest opportunity cost (US$ 57.91 ha−1.year−1), and 99 rural properties with areas of interest for PES schemes were identified (3.7% of the watershed area), corresponding in full to the payment amount of US$ 52,018.08 per year to producers. Finally, the use of multicriteria evaluation combined with economic analysis of land use presented as a flexible and straightforward methodological approach, whose results can support further watershed planning and management.

Space-temporal dynamics of land use and occupation in the Municipality of Ribeirão Preto, São Paulo, Brazil

The territorial planning in the Southeast Region of Brazil was marked by marked economic cycles of land use and occupation. To assess this dynamic, surveys of historical and natural data from Ribeirão Preto – SP. In this context, the method of space-temporal analysis was adopted, based on the mapping of land use and occupation, from the reconstitution of the map of the use of 1910, together with the mapping of satellite images and aerial photographs by the method of oriented classification the object of 1973, 1985, 1995, 2005, 2015, 2019. The objective was to quantify the uses, trace trends, evaluate the effectiveness of public policies and highlight potential and environmental risks. The maps reveal the growth and expansion of agricultural frontiers, which indicates a change in the region's economic base, which has gone from being a major coffee producer to a sugarcane and agribusiness production hub. Such changes reflect the drop in the price of coffee and the federal programs to encourage the production of sugar and ethanol. Thus, the land ownership structure has not undergone major changes and continues to be dominated by large properties, but now managed by holding companies and anonymous society. Urbanization took place at an accelerated rate and was driven by the green revolution, mainly from 1960, resulting in the strong rural exodus in the region. This process resulted in a series of socio-environmental impacts, related to irregular occupations of areas for housing and increased urban and rural violence, in addition to the increased demand for natural resources, such as, for example, the increased demand for water and consequently of the waters of the Guarani Aquifer System, which resulted in the lowering of the water table and caused restrictions on its use. In addition, the region's native vegetation has been almost completely deforested and the soils show signs of accelerated erosion locally, which tends to have a deleterious impact on surface water resources, which are already suffering from municipal and industrial effluent discharge. In this context, the Ribeirão Preto region is a global agricultural economic hub, which depends on its natural potential. Therefore, the sustainable planning of territorial use and occupation should have as a priority to protect and preserve these natural resources, given the historical dependence of the municipality on it.

CHEMICAL AND PHYSICAL ANALYSIS OF SANDSTONE ROCK FROM BOTUCATU FORMATION

The productive capacity of the Guarani Aquifer System is subject to variations along its length, due to its complex structural and compositional heterogeneity. Several parameters may influence the quality of this reservoir rock, such as its mineralogical and textural constitution, as well as the physicochemical processes, since its diagenesis is not the same throughout the aquifer, influencing the water productivity in wells in different locations. Such parameters are useful in the geoscience studies for the elaboration of diagenetic models for the prediction of the reservoir quality. In this work, several properties of the sandstone rock from Botucatu Formation were determined using different techniques, such as geotechnical tests, optical microscopy (MO), electron scanning microscopy (SEM), X-ray Fluorescence and X-ray diffraction. The results indicate that the studied sandstones have characteristics of the reservoir rocks, with potential for water storage.

Compartmentation in the Guarani Aquifer System northeastern region of the Rio Grande do Sul State

This study aims to evaluate the structural compartmentation of the Guarani Aquifer System (GAS) in the northeastern region of the Rio Grande do Sul (RS) state. For this purpose, an integrated analysis of 747 morphostructural lineaments identified in the scale 1:1,000,000 with geometry features and potentiometry of the GAS was performed. Based on this evaluation, a main set of structures, N30W and N60E oriented, responsible for the GAS compartmentation within the study area, was identified. These directions are related to the main tectonic structures that originated from the basement of the Paraná Basin, which could indicate that these identified structures are part of large fault systems in this region. The variations in the GAS potentiometry and altimetry of the top related to the compartmentation show the existence of several blocks formed under the influence of NW and NE structures located mainly in the large valleys, which sometimes work as a discharge zone of the aquifer. According to the analysis, the GAS in the northeastern region of RS seems to be divided into compartments of different sizes. This structural and geometrical framework imposed by tectonic structures influences the GAS potentiometry and flow dynamics.

Interpreting regolith data to infer groundwater potential contamination in Piracicaba, Brazil

Interdisciplinary concepts have been used to manage the environmental crisis of the 21st century. Ecological problems and solutions require an increasingly comprehensive soil study and this has been carried out in order to consider the entire regolith profile. Regoliths are the entire column of materials above the fresh rock, whether this is saprolite (literally “rotten rock”) or soil, material with intense biological and chemical process. Groundwater contamination is particularly enhanced in shallow, porous regolith profiles, due to the easiness of surface water flow into the groundwaters. This is particularly critical in the Guarani aquifer, which waters supplies 15 million people in 4 countries. Several morphological, chemical, physical and mineralogical analyses were applied to samples collected in three regolith profiles to infer, based on weathering and pedogenesis characteristics, their susceptibility to allow groundwater contamination. A particular challenge was that most of the weathering indices were proposed for igneous rocks, and the studied profiles had sedimentary rocks as parent materials. The most weathered profile (P2) had the least potential for groundwater contamination due to its higher cation exchange capacity (CEC) and clay activity, differentiated structure and consistency in the Bi horizon that can favor the lateral flow and the greatest thickness. Profile P1 had sandy texture, small CEC and thickness that facilitate the passage of soluble contaminants towards the groundwater. Some anox features in the Cr layer suggest the existence of a physical limitation that may delay infiltration or diverge water flow to surface outlets. The profile P3 had the greatest potential for groundwater contamination because it had low CEC, weathering degree and thickness. The only feature to prevent the polluted infiltration water to reach groundwaters in this profile was its sub-horizontal structure and transition from soft/very friable consistency in CA layer to very hard/unbreakable consistency in Cr layer, which also may diverge or delay the vertical infiltration of water. However, no anox features were found in it. Results indicate the importance of understanding the soil weathering and relate with their potential on underground water contamination, and thus, to bring light to public environmental monitoring policies.

Hydrogeochemical and Geophysical Evaluation of the Recharge Zone of Guarani Aquifer in Municipally of Candelária, Rio Grande do Sul, Brazil

A large part of the Guarani Aquifer is located in the state of Rio Grande do Sul (Brazil) and additionally possesses a recharge area located in its central and western region, therefore, this study was focused in one of these regions, specifically in the municipality of Candelaria. Currently, there is no water resources plan in the state and, for this reason, to construct it, a first step was done by means of hydrogeochemical and geophysical characteristics of the Aquifer recharge region. Some data were acquired, gathered, processed and analyzed, including chemical analysis of water in different wells and geophysical surveys in refraction seismic and geoelectrical methods by a dipole-dipole array. With all the data, it was proceeded to make different maps of chemical parameters and a Piper diagram, finding a high iron and arsenic concentration, as well as high alkalinity in water. Additionally, by means of geophysical surveys, a line was pointed as possible aquifer reservoir, which could be used for human, agropastoral or industrial purposes after treatments.

Resurfaced paleodunes from the Botucatu erg amid Cretaceous Paraná volcanics

Extensive exposure of Cretaceous paleodunes partly covered by basaltic rocks is a rare surficial structure in the geomorphology of continents. The Paraná Basin offers the opportunity in southernmost Brazil to study the relationships between the major Botucatu paleoerg-turned into the Guarani Aquifer (1.2 million km2) and the overlying, first flows from the Paraná Volcanic Province (1 million km2). We describe the Inhanduí Paleodune Field (IPDF; 15,000 km2) preserved by the first two (up to six) flows of the Paraná Volcanic Province. The field was exposed by erosion of volcanic overburden in Fronteira Oeste of southernmost Brazil. A plan view of the field is examined in the extensive grasslands and rice crops of the pampas. Observational geology from satellite images was followed by field description, gammaspectrometry, petrography and whole-rock geochemistry. Results show that bedforms include thousands of varied individual and compound paleodunes, including crescentic (barchane), linear, circle (blowout), and complex forms. Cerro do Jarau was considered an impact crater, and is here characterized as a compound paleodune. The paleoerg sand was silicified and deformed by hot water from the Guarani aquifer and the explosion of vapor in IPDF. The active dunes were flooded with tholeiitic lavas; heating by residual heat from volcanism (raised geothermal gradient) led to sand injection into overlying volcanic rocks. Silicification accompanied and followed the injection process. The Botucatu Formation includes the paleodunes and was the source bed of the sand injectites (Novo Hamburgo Complex) into the overlying volcanic group. We thus uncovered the processes associated with the flooding of a major, active erg by lavas from a large volcanic province. Hyperdry climate prevailed in the sandy Botucatu desert and continued in the rocky Serra Geral desert. The studied geological relationships are unique in the geological records; their understanding fosters the correct description of geological evolution of other terrains where some of the parameters are present.

Variation of Diatoms at Different Scales in the Brazilian Pantanal Basin

(1) Background: We analyzed the diatom community structure of the surface sediments, in three permanent ponds in the Pantanal of Mato Grosso, Brazil, to better understand how biota in these aquatic environments depend on structural connectivity and functional connectivity: (2) Methods: Ten samples sites were established in each pond, water and the sediment were taken during the flood period. Abiotic–biotic variables were determined and standardized; (3) Results: The three ponds presented acidic water and high concentration of nitrogen, with the highest acidity for Ferradura Pond (P1) and the highest trophic status index for Burro Pond (P2), but the greatest environmental variations occurred in Caracará Pond (P3). The variation in diversity between sites in the same pond is what contributes the most to gamma diversity. The most abundant species was Aulacoseiraitalica (Ehrenberg) Simonsen and the genus Eunotia Ehrenberg was the most representative in species. Ferradura Pond, there was a relationship between compositional and environmental dissimilarities with geographic distance, but there was no independent. Burro Pond, the relationship the compositional variation with environmental variables was not significant. Caracará Pond, there was a relationship of compositional dissimilarity both with geographical distance and with environmental; (4) Conclusions: The set of results suggests that the mechanisms that determine the metacommunity of each pond are different and that the environmental conditions and dispersion influenced the structure and composition. Since, diatom species were different between ponds, and ponds more eutrophic showed less diversity. The pH and oligotrophy were the main factors to maintain the greatest diversity of species of the genus Eunotia and the greatest abundance of Aulacoseira italica. Knowing the dynamics and structure of diatoms, which are at the beginning of the food chain, is essential for conserving, maintaining, or rehabilitating wetland ecosystems, such as the Pantanal, which is part La Plata river basin, which represents the second largest surface for water resources in South America and the Guarani Aquifer System, the biggest unified groundwater aquifer in the world.

Enteric viruses in lentic and lotic freshwater habitats from Brazil's Midwest and South regions in the Guarani Aquifer area.

The present study reports the monitoring of viruses indicating fecal contamination in two distinct regions affected by poor management of wastewater located above the Guarani Aquifer, which is one of the biggest freshwater reservoirs in the world. In the city of Três Lagoas (located in the Midwest region, in the state of Mato Grosso do Sul), water samples were collected from Lagoa Maior, a lake used for recreation, and in Concórdia (located in the South region, in the state of Santa Catarina), from the Queimados River, which crosses the urban area. Four sampling sites were monitored from March to July 2018 in Lagoa Maior, and four sampling sites were monitored along the urban part of the Queimados River area over two periods (rainy and dry). Water samples were analyzed by concentration of Human adenovirus (HAdV), Norovirus (NoV), Rotavirus A (RAV), and Hepatitis A virus (HAV) for the Lagoa Maior samples and RVA, HAV, and Porcine circovirus 2 (PCV2) for the Queimados River samples. All sampling sites presented enteric viruses, demonstrating fecal input and potential contamination of groundwater. Results highlight the need for wastewater management to improve environmental health quality.

Assessment of groundwater recharge along the Guarani aquifer system outcrop zone in São Paulo State (Brazil): an important tool towards integrated management

The quantification of the groundwater recharges represents useful and important information for water resource management. The volumes of infiltrated water are essential to maintain water storage in aquifers, as well as to the discharge of groundwater towards the rivers, especially in tropical areas. The outcrop zones of the Guarani Aquifer System (GAS) in Sao Paulo state (Brazil) are considered as their most important recharge areas; therefore, knowledge about recharge rates and processes is essential. They are also highly vulnerable to groundwater contamination, another important reason to protect them. This study aimed to estimate spatial and temporal variations of groundwater recharge in the mentioned GAS outcrop zones. Recharge rates were estimated using the Spatial Recharge (SR) method and then compared to other two traditional methods (base flow separation and water table fluctuation method). The SR method uses the spatial distribution of the evapotranspiration and rainfall from GLDAS and TRMM databases and the runoff after the Soil Conservation Service (SCS) empirical method. All three methods revealed similar estimates for groundwater recharge, ranging from 150 to 370 mm year−1 (about 17% of the total rainfall). Despite its intrinsic limitations, the SR method allowed robust recharge estimation with ability to cope with spatial and temporal variations, as well, especially in areas lacking hydrological monitoring programs. The SR method provides valuable information for water management policymakers and stakeholders to minimize impacts related to climatic variations and inappropriate land use on recharge processes.

Water level alterations on the southern rim of the Guarani Aquifer due to the rain regime

Abstract This paper estimated the total water storage variation in the southern rim of the Guarani Aquifer System during a three-year time span, making use of data provided by the Gravity Recovery and Climate Experiment. Monthly data were used to estimate the Bouguer anomaly in Southern Brazil. A direct modeling, using the Bouguer plateau, was applied to quantitatively estimate the water volume variation of a specific thickness in the studied region. Meteorological almanac data were compared to the gravitational alterations. We found a direct proportionality between the monthly rain average and the water table level. A simple model was found to forecast water accumulation as a function of rainfall regime, which is validated by a Pearson index of 0.82 that indicates a strong correlation between pluviometric and gravimetric data. In order to raise the stored water level near the recharge area by 1 mm, approximately 3 mm of rainfall is needed.