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Management of saltwater intrusion in coastal aquifers using different wells systems: a case study of the Nile Delta aquifer in Egypt | Gestion de l’intrusion d’eau salée dans les aquifères côtiers faisant appel à différents systèmes de puits: étude du cas de l’aquifère du Delta du Nil en Egypte Gerenciamento da intrusão salgada em aquíferos costeiros utilizando diferentes sistemas de poços: um estudo de caso no aquífero do Delta do Nilo no Egito 使用不同的井系统管理沿海含水层的盐水入侵:以埃及尼罗河三角洲含水层为例 Gestión de la intrusión de agua salada en acuíferos costeros utilizando diferentes sistemas de perforaciones: un estudio de caso del acuífero del Delta del Nilo en Egipto Full text
2021
Abd-Elaty, Ismail | Javadi, Akbar A. | Abd-Elhamid, Hany
Saltwater intrusion (SWI) is a type of pollution that adversely affects the quality of groundwater in coastal aquifers. The Nile Delta aquifer (NDA) in Egypt contains a large amount of freshwater. Increasing abstraction from the aquifer and sea level rise have led to an increase in SWI, which has reached up to 100 km inland. Therefore, practical measures are required to prevent further SWI. This study aims to identify an optimal well system to manage the intrusion of saline water in NDA using a number of management systems, including pumping of brackish water, aquifer recharge, and abstraction of the freshwater. SEAWAT code is used to simulate SWI in the aquifer considering different scenarios of pumping and sea level rise. Four scenarios are used to control SWI, including: decreasing pumping from the aquifer, increasing recharge using treated waste water, increasing abstraction of brackish water for desalination, and a combination of these systems. The results showed that increasing recharge could lead to greater retardation of SWI (19.5%) than decreasing pumping (6.2%) and abstraction of brackish water (5.9%). However, a combined well system of pumping, recharge and abstraction is shown to be a more effective tool to control SWI in coastal aquifers, with retardation percentage of 21.3%.
Show more [+] Less [-]Hydro-geomechanical characterisation of a coastal urban aquifer using multiscalar time and frequency domain groundwater-level responses | Caractérisation hydrogéomécanique d’un aquifère côtier urbanisé à l’aide des réponses multiscalaires du niveau des eaux souterraines dans le domaine temporel et fréquentiel Caracterización hidrogeomecánica de un acuífero urbano costero mediante el uso de respuestas multiescalares en el dominio del tiempo y la frecuencia del nivel freático 使用多标量时域和频域地下水位响应对沿海城市含水层进行水文地质力学表征 Caracterização hidrogeomecânica de um aquífero costeiro urbano usando tempo multiescalar e respostas no nível da água subterrânea no domínio da frequência Гидрогеомеханическая характеризация прибрежного городского водоносного горизонта с использованием многомасштабного анализа откликов уровня грунтовых вод во временной и частотной областях Full text
2021
Patton, Ashley M. | Rau, Gabriel C. | Cleall, Peter J. | Cuthbert, Mark O.
Hydraulic properties of coastal, urban aquifers vary spatially and temporally with the complex dynamics of their hydrogeology and the heterogeneity of ocean-influenced hydraulic processes. Traditional aquifer characterisation methods are expensive, time-consuming and represent a snapshot in time. Tidal subsurface analysis (TSA) can passively characterise subsurface processes and establish hydro-geomechanical properties from groundwater head time-series but is typically applied to individual wells inland. Presented here, TSA is applied to a network of 116 groundwater boreholes to spatially characterise confinement and specific storage across a coastal aquifer at city-scale in Cardiff (UK) using a 23-year high-frequency time-series dataset. The dataset comprises Earth, atmospheric and oceanic signals, with the analysis conducted in the time domain, by calculating barometric response functions (BRFs), and in the frequency domain (TSA). By examining the damping and attenuation of groundwater response to ocean tides (OT) with distance from the coast/rivers, a multi-borehole comparison of TSA with BRF shows this combination of analyses facilitates disentangling the influence of tidal signals and estimation of spatially distributed aquifer properties for non-OT-influenced boreholes. The time-series analysed covers a period pre- and post-impoundment of Cardiff’s rivers by a barrage, revealing the consequent reduction in subsurface OT signal propagation post-construction. The results indicate that a much higher degree of confined conditions exist across the aquifer than previously thought (specific storage = 2.3 × 10⁻⁶ to 7.9 × 10⁻⁵ m⁻¹), with implications for understanding aquifer recharge, and informing the best strategies for utilising groundwater and shallow geothermal resources.
Show more [+] Less [-]Groundwater investigation of the artesian wells on the palaeochannels in parts of the Great Rann of Kachchh, Gujarat, India, using remote sensing and geophysical techniques | Étude hydrogéologique des puits artésiens implantés au niveau de paléochenaux dans certaines parties du Grand Rann de Kachchh, Gujarat, Inde, à l’aide de techniques de télédétection et de géophysique Investigación de las aguas subterráneas en los pozos artesianos de los paleocanales en zonas del Great Rann of Kachchh, Gujarat, India, mediante técnicas de teledetección y geofísicas 使用遥感和地球物理技术对印度古吉拉特邦部分卡奇大沼泽古河道自流井开展地下水调查 Investigação da água subterrânea de poços artesianos nos paleocanais em partes do Grande Rann de Kachchh, Gujarat, Índia, usando sensoriamento remoto e técnicas geofísicas Full text
2021
Bhadra, B. K. | Gor, Naresh | Jain, Ashish K. | Meena, Hansraj | Srinivasa Rao, S.
The Great Rann of Kachchh (GRK) in Gujarat, India, is the largest salt desert in the world, which is usually filled with seawater ingression during high tide from the Arabian Sea. As a result, the soil gets saturated with saline water that has percolated down for several meters. Groundwater exploration in Rann area is a challenging task due to the prevailing hostile environment. For this purpose, multisensor satellite data have been used to delineate the palaeochannels in search of an alternate source of drinking water. In GRK, palaeochannels represent the zone of elevated fluvial sediments with respect to the surroundings. Evolutionary history of the palaeochannels indicates upliftment of GRK area during Allah Bund faulting. For assessing the groundwater potential of the palaeochannels, high-resolution electrical resistivity tomography (HERT) surveys have been carried out with the pole-dipole method. Electrical resistivity tomograms along 710 m traverses to a depth of 250 m in Dharmsala and Gainda area show higher-resistivity zones (medium to coarse sand with brackish water) below a thick low-resistivity layer (clay with saline water). A few exploratory drillings in the area confirm the existence of the palaeochannels, which act as a confined aquifer below 100 m depth. The artesian condition of the two drilled wells at Gainda and Khardoi along the northern boundary of GRK may be attributed to hydraulic gradient along the confined layers from the Tharparkar region in Pakistan. Thus, HERT is found to be a faster and more cost-effective geophysical survey technique for study of the deep aquifer.
Show more [+] Less [-]Understanding long-term groundwater flow at Pahute Mesa and vicinity, Nevada National Security Site, USA, from naturally occurring geochemical and isotopic tracers | Compréhension des écoulements à long terme des eaux souterraines à Pahute Mesa et dans les environs, Nevada National Security Site, Etats-Unis d’Amériques, à partir de traceurs géochimiques et isotopiques d’origine naturelle Reconocimiento del flujo de agua subterránea a largo plazo en Pahute Mesa y sus alrededores, Nevada National Security Site, EE.UU., a partir de trazadores geoquímicos e isotópicos naturales 基于天然地球化学和同位素示踪剂了解美国内华达州国家安全区Pahute Mesa 及附近的长期地下水运动 Entendendo o fluxo de águas subterrâneas de longo termo em Pahute Mesa e proximidades, Nevada National Security Site, EUA, a partir da ocorrência natural de traçadores isotópicos e geoquímicos Full text
2021
Kwicklis, Edward | Farnham, Irene | Hershey, R. L. (Ronald L.) | Visser, Ate | Hoaglund, John III
Recently collected naturally occurring geochemical and isotopic groundwater tracers were combined with historic data from the Pahute Mesa area of the Nevada National Security Site (NNSS), Nevada, USA, to provide insights into long-term regional groundwater flow patterns, mixing and recharge. Pahute Mesa was the site of 85 nuclear detonations between 1965 and 1992, many of them deeply buried devices that introduced radionuclides directly into groundwater. The dataset examined included major ions and field measurements, stable isotopes of hydrogen (δ²H), oxygen (δ¹⁸O), carbon (δ¹³C) and sulfur (δ³⁴S), and radioisotopes of carbon (¹⁴C) and chloride (³⁶Cl). Analysis of the patterns of groundwater ¹⁴C data and the δ²H and δ¹⁸O signatures indicates that groundwater recharge is predominantly of Pleistocene age, except for a few localized areas near major ephemeral drainages. Steep gradients in sulfate (SO₄) and chloride (Cl) define a region near the western edge of the NNSS where high-concentration groundwater flowing south from north of the NNSS merges with dilute groundwater flowing west from eastern Pahute Mesa in a mixing zone that coincides with a groundwater trough associated with major faults. The ³⁶Cl/Cl and δ³⁴S data suggest that the source of the high Cl and SO₄ in the groundwater was a now-dry, pluvial-age playa lake north of the NNSS. Patterns of groundwater flow indicated by the combined data sets show that groundwater is flowing around the northwest margin of the now extinct Timber Mountain Caldera Complex toward regional discharge areas in Oasis Valley.
Show more [+] Less [-]Assessment of future trends on groundwater quality in a nitrate vulnerable zone (Esposende–Vila do Conde sector, NW Portugal): towards a combined conceptual and mass transport modelling | Évaluation des tendances futures de la qualité des eaux souterraines dans une zone vulnérable aux nitrates (secteur Esposende-Vila do Conde, NW Portugal): vers une modélisation combinée conceptuelle et de transport de masse Evaluación de tendencias futuras en la calidad de las aguas subterráneas en una zona vulnerable a los nitratos (sector Esposende-Vila do Conde, noroeste de Portugal): hacia una modelización conceptual y combinada con el transporte de masas 评估易受硝酸盐影响区(葡萄牙西北部Esposende–Vila do Conde地区)地下水质量的未来趋势:结合概念模型与质量传输模型来 Avaliação de tendência da qualidade da água subterrânea numa zona vulnerável aos nitratos (Esposende–Vila do Conde, NW Portugal): combinação dos modelos conceptual e numérico com transporte de massa Full text
2021
Zeferino, Joel | Carvalho, Maria Rosário | Lopes, Ana Rita | Jesus, Rosário | Afonso, Maria José | Freitas, Liliana | Carvalho, José Martins | Chaminé, Helder I.
Nitrate contamination of groundwater is an important public health issue worldwide. For environmental and public health reasons, water should not contain more than 50 mg/L NO₃. An aquifer for which this limit is exceeded can be designated as a nitrate vulnerable zone (NVZ) and subject to action programs to minimize the NO₃ input. The study aims to assess future trends of groundwater quality and to predict the time required for groundwater to achieve the environmental goals in the Esposende–Vila do Conde NVZ (Portugal). Flow and transient nitrate transport modelling were performed using the FEFLOW software. The numerical model represents the saturated zone of phreatic aquifers, designed in a three-dimensional three-layer model. The calibration process was completed through the tool FEPEST. Sensitivity analysis was performed to investigate the model response to changes in hydraulic parameters and aquifer recharge. Two major simulations of mass transport were performed considering different options on nitrogen loads: (1) agricultural nitrogenous loads of diffuse origin; (2) nitrogen loads from agricultural and livestock sectors together. The results show that the minimization measures imposed in the NVZ are effective, shown by the groundwater nitrate concentration decreasing over time; however, concentrations above 50 mg/L will persist for the next two decades in both simulated scenarios. Combining the conceptual hydrogeological model, geovisualization techniques, and numerical flow and mass transport modelling has been shown as a comprehensive approach to understanding the measures needed for sustainable water resources management and particularly to predicting hydraulic heads and NO₃ dispersion in aquifers.
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