Deciphering complex groundwater age distributions and recharge processes in a tropical and fractured volcanic aquifer system

Groundwater recharge in highly-fractured volcanic aquifers remains poorly understood in the humid tropics, whereby rapid demographic growth and unregulated land use change are resulting in extensive surface water pollution and a large dependency on groundwater extraction. Here we present a multi-tracer approach including δO-δH, H/He, and noble gases within the most prominent multi-aquifer system of central Costa Rica, with the objective to assess dominant groundwater recharge characteristics and age distributions. We sampled wells and large springs across an elevation gradient from 868 to 2,421 m asl. Our results suggest relatively young apparent ages ranging from 0.0±3.2 up to 76.6±9.9 years. Helium isotopes R/RA (0.99 to 5.4) indicate a dominant signal from the upper mantle across the aquifer. Potential recharge elevations ranged from ~1,400 to 2,650 m asl, with recharge temperatures varying from ~11°C to 19°C with a mean value of 14.5±1.9°C. Recharge estimates ranged from 129±78 to 1,605±196 mm/yr with a mean value of 642±117 mm/yr, representing 20.1±4.0% of the total mean annual rainfall as effective recharge. The shallow unconfined aquifer is characterised by young and rapidly infiltrating waters, whereas the deeper aquifer units have relatively older waters. These results are intended to guide the delineation and mapping of critical recharge areas in mountain headwaters to enhance water security and sustainability in the most important headwater dependent systems of Costa Rica.

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A multi-environmental tracer study to determine groundwater residence times and recharge in a structurally complex multi-aquifer system

Hydrology and Earth System Sciences ◽

10.5194/hess-24-249-2020 ◽

2020 ◽

Vol 24 (1) ◽

pp. 249-267 ◽

Cited By ~ 1

Author(s):

Cornelia Wilske ◽

Axel Suckow ◽

Ulf Mallast ◽

Christiane Meier ◽

Silke Merchel ◽

...

Keyword(s):

Groundwater Flow ◽

Groundwater Recharge ◽

Groundwater Age ◽

Age Distribution ◽

Dead Sea ◽

Artificial Sweetener ◽

Environmental Tracers ◽

Jordan Valley ◽

Aquifer System ◽

Lumped Parameter

Abstract. Despite being the main drinking water resource for over 5 million people, the water balance of the Eastern Mountain Aquifer system on the western side of the Dead Sea is poorly understood. The regional aquifer consists of fractured and karstified limestone – aquifers of Cretaceous age, and it can be separated into a Cenomanian aquifer (upper aquifer) and Albian aquifer (lower aquifer). Both aquifers are exposed along the mountain ridge around Jerusalem, which is the main recharge area. From here, the recharged groundwater flows in a highly karstified aquifer system towards the east and discharges in springs in the lower Jordan Valley and Dead Sea region. We investigated the Eastern Mountain Aquifer system for groundwater flow, groundwater age and potential mixtures, and groundwater recharge. We combined 36Cl ∕ Cl, tritium, and the anthropogenic gases SF6, CFC-12 (chlorofluorocarbon) and CFC-11, while using CFC-113 as “dating” tracers to estimate the young water components inside the Eastern Mountain Aquifer system. By application of lumped parameter models, we verified young groundwater components from the last 10 to 30 years and an admixture of a groundwater component older than about 70 years. Concentrations of nitrate, simazine (pesticide), acesulfame K (ACE-K; artificial sweetener) and naproxen (NAP; drug) in the groundwater were further indications of infiltration during the last 30 years. The combination of multiple environmental tracers and lumped parameter modelling helped to understand the groundwater age distribution and to estimate recharge despite scarce data in this very complex hydrogeological setting. Our groundwater recharge rates support groundwater management of this politically difficult area and can be used to inform and calibrate ongoing groundwater flow models.

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A multi-environmental tracer study to determine groundwater residence times and recharge in a structurally complex multi-aquifer system

10.5194/hess-2019-451 ◽

2019 ◽

Author(s):

Cornelia Wilske ◽

Axel Suckow ◽

Ulf Mallast ◽

Christiane Meier ◽

Silke Merchel ◽

...

Keyword(s):

Groundwater Flow ◽

Groundwater Recharge ◽

Groundwater Age ◽

Age Distribution ◽

Dead Sea ◽

Artificial Sweetener ◽

Environmental Tracers ◽

Jordan Valley ◽

Aquifer System ◽

Lumped Parameter

Abstract. Despite being the main drinking water resource for over five million people, the water balance of the Eastern Mountain Aquifer system on the western side of the Dead Sea is poorly understood. The regional aquifer consists of fractured and karstified limestone – aquifers of Cretaceous age and can be separated in Cenomanian aquifer (upper aquifer) and Albian aquifer (lower aquifer). Both aquifers are exposed along the mountain ridge around Jerusalem, which is the main recharge area. From here, the recharged groundwater flows in a highly karstified aquifer system towards the east, to discharge in springs in the Lower Jordan Valley and Dead Sea region. We investigated the Eastern Mountain Aquifer system on groundwater flow, groundwater age and potential mixtures, and groundwater recharge. We combined 36Cl/Cl, tritium and the anthropogenic gases SF6, CFC-12 and CFC-11, CFC-113 as dating tracers to estimate the young water components inside the Eastern Mountain Aquifer system. By application of lumped parameter models, we verified young groundwater components from the last 10 to 30 years and an admixture of a groundwater component older than about 70 years. Concentrations of nitrate, Simazine® (Pesticide), Acesulfame K® (artificial sweetener) and Naproxen® (drug) in the groundwater were further indications of infiltration during the last 30 years. The combination of multiple environmental tracers and lumped parameter modelling helped to understand the groundwater age distribution and to estimate recharge despite scarce data in this very complex hydrogeological setting. Our groundwater recharge rates support groundwater management of this politically difficult area and can be used to inform and calibrate ongoing groundwater flow models.

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Groundwater Recharge Decrease Replacing Pasture by Eucalyptus Plantation

Water ◽

10.3390/w11061213 ◽

2019 ◽

Vol 11 (6) ◽

pp. 1213 ◽

Cited By ~ 7

Author(s):

Tiago Souza Mattos ◽

Paulo Tarso Sanches de Oliveira ◽

Murilo Cesar Lucas ◽

Edson Wendland

Keyword(s):

Land Use ◽

Groundwater Recharge ◽

Annual Rainfall ◽

Southeastern Brazil ◽

Aquifer System ◽

Groundwater Levels ◽

Eucalyptus Plantation ◽

Before And After ◽

Guarani Aquifer ◽

Fluctuation Method

An important unsolved question in hydrology science is the consequence of the Eucalyptus afforestation on groundwater recharge. Here, we assessed recharge estimates before and after converting pasture cover to Eucalyptus plantation. Groundwater levels, recharge, rainfall (P) and actual evapotranspiration (ET) were evaluated from 2004 through 2016 over an outcrop area of the Guarani Aquifer System (GAS) in the southeastern Brazil. Recharge was estimated using the water-table fluctuation method. We observed a decrease of 100 mm/year in groundwater levels after land use changed from pasture to Eucalyptus. The average recharge decreased from 407 mm/year (27% of mean P) to 194 mm/year (13% of mean P) after land use change over the study area. We found a recharge decrease of 19% in 2012 and 58% in 2013 under similar annual rainfall in comparison with the long-term mean recharge (from 2004 to 2016). Our results indicated that the high values of ET observed in Eucalyptus plantation decreases water availability for recharge. Therefore, our findings are important to agencies for decision-making in water resources regarding the management of land cover and land use.

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Using groundwater levels and Specific Yield to Estimate the Recharge, South of Erbil, Kurdistan Region, Iraq

Academic Journal of Nawroz University ◽

10.25007/ajnu.v7n4a289 ◽

2018 ◽

Vol 7 (4) ◽

pp. 191

Author(s):

Sherwan Sh. Qurtas

Keyword(s):

Unconfined Aquifer ◽

Middle Part ◽

Water Levels ◽

Specific Yield ◽

Aquifer System ◽

Groundwater Levels ◽

Monitoring Wells ◽

Water Table Fluctuation Method ◽

Recharge Estimation ◽

Fluctuation Method

Recharge estimation accurately is crucial to proper groundwater resource management, for the groundwater is dynamic and replenished natural resource. Usually recharge estimation depends on the; the water balance, water levels, and precipitation. This paper is studying the south-middle part of Erbil basin, with the majority of Quaternary sediments, the unconfined aquifer system is dominant, and the unsaturated zone is ranging from 15 to 50 meters, which groundwater levels response is moderate. The purpose of this study is quantification the natural recharge from precipitation. The water table fluctuation method is applied; using groundwater levels data of selected monitoring wells, neighboring meteorological station of the wells, and the specific yield of the aquifers. This method is widely used for its simplicity, scientific, realistic, and direct measurement. The accuracy depends on the how much the determination of specific yield is accurate, accuracy of the data, and the extrapolations of recession of groundwater levels curves of no rain periods. The normal annual precipitation there is 420 mm, the average recharge is 89 mm, and the average specific yield is around 0.03. The data of one water year of 2009 and 2010 has taken for some technical and accuracy reasons.

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The Distribution of Volatile Organics in a Leachate Plume, Gloucester, Ontario

Water Quality Research Journal ◽

10.2166/wqrj.1987.004 ◽

1987 ◽

Vol 22 (1) ◽

pp. 49-64 ◽

Cited By ~ 1

Author(s):

J.F. Devlin ◽

W.A. Gorman

Keyword(s):

Organic Contaminants ◽

Source Area ◽

Unconfined Aquifer ◽

High Concentration ◽

Organic Contamination ◽

Aquifer System ◽

Aquifer Systems ◽

Volatile Organic ◽

Volatile Organic Contaminants ◽

Aquifer Sediments

Abstract The Gloucester Landfill is located near Ottawa, Ontario, on a northeast trending ridge of Quaternary age. The ridge comprises outwash sediments which make up two aquifer systems. A confined system exists next to bedrock, and is overlain by a silty-clayey stratum (the confining layer) which is, in turn, overlain by an unconfined aquifer system. Two independent volatile organic plumes have previously been identified at the landfill: the southeast plume, which has penetrated the confined aquifer system, and the northeast plume which is migrating in the unconfined aquifer. The distribution of volatile organic contaminants at the northeast plume site appears to be a function of two factors: (1) heterogeneities in the aquifer sediments are causing the channeling of contaminants through a narrow path; (2) the low fraction of organic carbon in the unconfined aquifer sediments at the northeast site is resulting in little retardation of the contaminants there, relative to those at the southeast site. Acetate was the only volatile fatty acid detected in the leachate. It was measurable only in areas where the volatile organic contamination was significant. Although methane was detected in the contaminated sediments, suggesting that microbial activity was present, the high concentration of acetate (>1000 ppm) which was detected down-gradient from the source area indicates that any biodegradation which is occurring is proceeding at a very slow rate.

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HYDROCHEMICAL ASSESSMENT OF UNCONFINED AQUIFER SYSTEM IN BAYAT MELANGE COMPLEX, KLATEN, INDONESIA

International Journal of Geomate ◽

10.21660/2017.39.17336 ◽

2017 ◽

Vol 13 (39) ◽

Keyword(s):

Unconfined Aquifer ◽

Aquifer System

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Testing Evapotranspiration Estimates Based on MODIS Satellite Data in the Assessment of the Groundwater Recharge of Karst Aquifers in Southern Italy

Water ◽

10.3390/w13020118 ◽

2021 ◽

Vol 13 (2) ◽

pp. 118

Author(s):

Giovanni Ruggieri ◽

Vincenzo Allocca ◽

Flavio Borfecchia ◽

Delia Cusano ◽

Palmira Marsiglia ◽

...

Keyword(s):

Groundwater Recharge ◽

Air Temperature ◽

Southern Italy ◽

Remotely Sensed ◽

Actual Evapotranspiration ◽

Annual Rainfall ◽

Karst Aquifers ◽

Southern Apennines ◽

Remotely Sensed Data ◽

Empirical Formulas

In many Italian regions, and particularly in southern Italy, karst aquifers are the main sources of drinking water and play a crucial role in the socio-economic development of the territory. Hence, estimating the groundwater recharge of these aquifers is a fundamental task for the proper management of water resources, while also considering the impacts of climate changes. In the southern Apennines, the assessment of hydrological parameters that is needed for the estimation of groundwater recharge is a challenging issue, especially for the spatial and temporal inhomogeneity of networks of rain and air temperature stations, as well as the variable geomorphological features and land use across mountainous karst areas. In such a framework, the integration of terrestrial and remotely sensed data is a promising approach to limit these uncertainties. In this research, estimations of actual evapotranspiration and groundwater recharge using remotely sensed data gathered by the Moderate Resolution Imaging Spectrometer (MODIS) satellite in the period 2000–2014 are shown for karst aquifers of the southern Apennines. To assess the uncertainties affecting conventional methods based on empirical formulas, the values estimated by the MODIS dataset were compared with those calculated by Coutagne, Turc, and Thornthwaite classical empirical formulas, which were based on the recordings of meteorological stations. The annual rainfall time series of 266 rain gauges and 150 air temperature stations, recorded using meteorological networks managed by public agencies in the period 2000–2014, were considered for reconstructing the regional distributed models of actual evapotranspiration (AET) and groundwater recharge. Considering the MODIS AET, the mean annual groundwater recharge for karst aquifers was estimated to be about 448 mm·year−1. In contrast, using the Turc, Coutagne, and Thornthwaite methods, it was estimated as being 494, 533, and 437 mm·year−1, respectively. The obtained results open a new methodological perspective for the assessment of the groundwater recharge of karst aquifers at the regional and mean annual scales, allowing for limiting uncertainties and taking into account a spatial resolution greater than that of the existing meteorological networks. Among the most relevant results obtained via the comparison of classical approaches used for estimating evapotranspiration is the good matching of the actual evapotranspiration estimated using MODIS data with the potential evapotranspiration estimated using the Thornthwaite formula. This result was considered linked to the availability of soil moisture for the evapotranspiration demand due to the relevant precipitation in the area, the general occurrence of soils covering karst aquifers, and the dense vegetation.

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Geochemical and isotopic evidence of groundwater salinization processes in the Essaouira region, north-west coast, Morocco

SN Applied Sciences ◽

10.1007/s42452-021-04623-3 ◽

2021 ◽

Vol 3 (7) ◽

Author(s):

Otman EL Mountassir ◽

Mohammed Bahir ◽

Driss Ouazar ◽

Abdelghani Chehbouni ◽

Paula M. Carreira

Keyword(s):

Groundwater Recharge ◽

West Coast ◽

Exchange Process ◽

Environmental Isotopes ◽

Annual Rainfall ◽

Groundwater Salinization ◽

Rock Interaction ◽

North West ◽

The North ◽

Water Rock Interaction

AbstractThe city of Essaouira is located along the north-west coast of Morocco, where groundwater is the main source of drinking, domestic and agricultural water. In recent decades, the salinity of groundwater has increased, which is why geochemical techniques and environmental isotopes have been used to determine the main sources of groundwater recharge and salinization. The hydrochemical study shows that for the years 1995, 2007, 2016 and 2019, the chemical composition of groundwater in the study area consists of HCO3–Ca–Mg, Cl–Ca–Mg, SO4–Ca and Cl–Na chemical facies. The results show that from 1995 to 2019, electrical conductivity increased and that could be explained by a decrease in annual rainfall in relation to climate change and water–rock interaction processes. Geochemical and environmental isotope data show that the main geochemical mechanisms controlling the hydrochemical evolution of groundwater in the Cenomanian–Turonian aquifer are the water–rock interaction and the cation exchange process. The diagram of δ2H = 8 * δ18O + 10 shows that the isotopic contents are close or above to the Global Meteoric Water Line, which suggests that the aquifer is recharged by precipitation of Atlantic origin. In conclusion, groundwater withdrawal should be well controlled to prevent groundwater salinization and further intrusion of seawater due to the lack of annual groundwater recharge in the Essaouira region.

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