scholarly journals DC resistivity investigation in a fractured aquifer system contaminated by leachate from an old dump

2017 ◽  
Vol 56 (4) ◽  
Author(s):  
César Augusto Moreira ◽  
Carolina Gonçalves Leandro ◽  
Camila Trindade Lopes ◽  
Lenon Melo Ilha
Keyword(s):  
Federal Law ◽  
Fractured Aquifer ◽  
Geophysical Investigation ◽  
Resistivity Tomography ◽  
Aquifer System ◽  
Monitoring Wells ◽  
Sanitary Landfills ◽  
3D Processing ◽  
Environmental Agencies ◽  
2D And 3D

The dumps are areas of final disposal of solid wastes directly into the soil, with no technical criteria or collecting systems of gases or liquids. A large part of Brazilian municipalities have used this extreme damaging alternative to the environment up to the year 2010, when a federal law made compulsory the installation of sanitary landfills. However, large parts of the dumps were simply abandoned, although some eventually go through treatment after assessments of the state environmental agencies. This work presents the results of a geophysical investigation in a dump deactivated in 2004 in a small city in southern Brazil, where previous investigations have revealed contamination of soil and groundwater by leachate. Structural analyzes in the area of study combined to geological data from monitoring wells indicate the presence of contaminants in fractured granite, with a wide variation in the thickness of soil, saprolite and groundwater level. The integration of chemical analyses of the groundwater with electrical resistivity tomography (ERT) in 2D and 3D processing, revealed the existence of large contaminated areas within the limits of the dump flowing into the aquifer partially free up to 5m depth. Such areas may decrease gradually with the increase in depth and between 9m and 19m contaminated zones clearly predominate, associated with the flow in the fractured aquifer. The indication of restricted and oriented zones suggests the targeting and accumulation of contaminants in two systems of preferential fractures. The discovery of these zones is fundamental for planning and the installation of pumping and decontamination systems of groundwater, considering a declining production of leachate since the closure of the dump.

scholarly journals Geophysical investigation and its geological interpretation in the frame of an intergrated survey prior to a dam construction in Plati River Valley, Rethymno, Greece.

2016 ◽  
Vol 47 (3) ◽  
pp. 1052
Author(s):  
G. Apostolopoulos ◽  
C. Pavlaki ◽  
V. Perleros ◽  
G. Amolochitis
Keyword(s):  
River Valley ◽  
Clay Material ◽  
Geophysical Investigation ◽  
Resistivity Tomography ◽  
Geological Interpretation ◽  
Total Length ◽  
Lateral Inhomogeneity ◽  
Loose Sediments ◽  
Extended Area ◽  
2D And 3D

A geophysical survey using electrical resistivity tomography (ERT) method(25 ERT profiles of 240m total length and 2 ERT profiles of 1000m total length) in the area of Plati River valley gave valuable information regarding the stratigraphy, related to loose sediments, various faces of flysch and limestone, the tectonic status and the detection of areas of thick and extensive sheared siltstone, that geoelectrically is similar to clay,material useful for the core of the future dam. Both branches of river and valley and in greater detail the area near the position of the dam have detected showing the underground in a 2D and 3D manner. The thickness of neogene andflysch exceeds 40m. Alternations of siltstones-sandstones are met in flysch and in places cohesive sandstones are also met without continuation in an extended area. The siltstonelayers due to their shear character present clayey characteristics in respect of their resistivities. In general zones of limestone uplift have not been detected, which may create problems of leakages apart of the dam area where lateral inhomogeneity between flysch and limestone has been detected (probable fault). The various limestone bodies met in flysch or neogene do not have continuation in depth and they are isolated. 

scholarly journals ANÁLISE DA RECARGA NO SISTEMA AQUÍFERO GRANULAR E FISSURAL NA ÁREA DO CAMPUS PAMPULHA DA UNIVERSIDADE FEDERAL DE MINAS GERAIS

2014 ◽  
Author(s):  
João Pedro Marques Ribeiro ◽  
Leila Nunes Menegasse Velásquez ◽  
Carlos Alberto de Carvalho Filho ◽  
Peter Marshall Fleming
Keyword(s):  
Water Level ◽  
Minas Gerais ◽  
Aquifer Recharge ◽  
Fractured Aquifer ◽  
Hydraulic Connection ◽  
Aquifer System ◽  
Monitoring Wells ◽  
Deep Wells ◽  
Belo Horizonte ◽  
Granular Aquifer

No presente estudo analisou-se a recarga no sistema aquífero existente na área do campus Pampulha da UFMG, em Belo Horizonte, Minas Gerais. Este Sistema Aquífero é composto por dois aquíferos em um ambiente geológico com duas identidades litoestratigráficas distintas. Sendo, um aquífero granular, sobrejacente, caracterizado pelo manto de intemperismo, e um aquifero fraturado, subjacente, caracterizado por rochas do Complexo Belo Horizonte, principalmente gnaisses e granitos. A área de estudo possui uma rede de poços tubulares profundos e poços de monitoramento, formada por doze poços tubulares profundos e sete poços de monitoramento. Neste estudo a recarga foi qualificada a partir de premissas das principais variáveis que a influenciam, entre elas a precipitação, a litologia, a profundidade do nível potenciométrico e o relevo. O trabalho se baseou em dados pré-existentes advindos do monitoramento do nível d’água, realizado entre 1997 e 2000, em poços e piezômetros existentes na área de estudo. A análise estatística apontou a precipitação e a textura dos solos como os fatores que mais influenciam na recarga local. Foi constatado que há uma conexão hidráulica entre os dois aquíferos e, por conseguinte uma recarga indireta do aquífero superior para o basal.Palavras-chave: Recarga direta; monitoramento de nível d’água; conexão hidráulica; aqüíferos poroso e fraturado. Abstract: ANALYSIS ON RECHARGE OF AQUIFER SYSTEM GRANULAR AND FISSURE ON UFMG CAMPUS AREA, BELO HORIZONTE, MG. In the present paper we analyzed the existing aquifer recharge system in the campus area UFMG, in Belo Horizonte, Minas Gerais. This aquifer system consists of two aquifers in a geological environment with two distinct lithostratigraphic identities. Being a granular aquifer, overlying, characterized by weathering mantle, and a fractured aquifer, underlying, characterized by rocks of the Complex Belo Horizonte, mainly gneisses and granites. The study area has a network of deep wells and monitoring wells, formed by twelve deep wells and seven monitoring wells. In this study the clearance was qualified from the premises of the main variables that influence it, including precipitation, lithology, depth of potentiometric level and relief. The work was based on pre-existing data obtained from the monitoring of the water level, conducted between 1997 and 2000 in existing wells and piezometers in the study area. The statistical analysis showed precipitation and soil texture as the factors that most influence in local recharge. It has been found that there is a hydraulic connection between the two aquifers and therefore an indirect upper aquifer recharge to baseline.Keywords: Recharge; water level monitoring; hydraulic connection; fractured and granular aquifer. 

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

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.

scholarly journals Seismically induced changes in groundwater levels and temperatures following the ML5.8 (ML5.1) Gyeongju earthquake in South Korea

2021 ◽  
Author(s):  
Soo-Hyoung Lee ◽  
Jae Min Lee ◽  
Sang-Ho Moon ◽  
Kyoochul Ha ◽  
Yongcheol Kim ◽  
...  
Keyword(s):  
South Korea ◽  
Groundwater Level ◽  
Seismic Waves ◽  
Groundwater Resources ◽  
Fluid Pressure ◽  
Water Levels ◽  
Aquifer System ◽  
Groundwater Levels ◽  
Monitoring Wells ◽  
Gyeongju Earthquake

AbstractHydrogeological responses to earthquakes such as changes in groundwater level, temperature, and chemistry, have been observed for several decades. This study examines behavior associated with ML 5.8 and ML 5.1 earthquakes that occurred on 12 September 2016 near Gyeongju, a city located on the southeast coast of the Korean peninsula. The ML 5.8 event stands as the largest recorded earthquake in South Korea since the advent of modern recording systems. There was considerable damage associated with the earthquakes and many aftershocks. Records from monitoring wells located about 135 km west of the epicenter displayed various patterns of change in both water level and temperature. There were transient-type, step-like-type (up and down), and persistent-type (rise and fall) changes in water levels. The water temperature changes were of transient, shift-change, and tendency-change types. Transient changes in the groundwater level and temperature were particularly well developed in monitoring wells installed along a major boundary fault that bisected the study area. These changes were interpreted as representing an aquifer system deformed by seismic waves. The various patterns in groundwater level and temperature, therefore, suggested that seismic waves impacted the fractured units through the reactivation of fractures, joints, and microcracks, which resulted from a pulse in fluid pressure. This study points to the value of long-term monitoring efforts, which in this case were able to provide detailed information needed to manage the groundwater resources in areas potentially affected by further earthquakes.

scholarly journals CONTRIBUTION OF DEEP ELECTRICAL RESISTIVITY TOMOGRAPHY TECHNIQUE TO HYDROGEOLOGICAL STUDIES: CASES FROM AREAS IN KAVALA (NORTH GREECE)

2017 ◽  
Vol 43 (4) ◽  
pp. 1962
Author(s):  
G. Vargemezis ◽  
P. Tsourlos ◽  
I. Mertzanides
Keyword(s):  
Electrical Resistivity ◽  
Electrical Resistivity Tomography ◽  
Geological Structure ◽  
Resistivity Tomography ◽  
Near Surface ◽  
Resistivity Method ◽  
Area Of Interest ◽  
Vertical Electric Sounding ◽  
Hydrogeological Studies ◽  
2D And 3D

The most common geophysical method widely used in hydrogeological surveys concerning deep investigations (150-300m of depth) is the resistivity method and particularly the Vertical Electric Sounding (VES) using the Schlumberger array. VES interpretations assume 1D geoelectrical structure yet it is obvious that such an interpretation assumption is not valid in many cases where 2D and 3D geological features exist. In such cases the application of geoelectrical techniques which can provide both vertical and lateral information concerning the resistivity variations is required. Techniques such as the electrical resistivity tomography, mostly used for the 2D and 3D geoelectrical mapping of near surface applications can be adapted to be used for larger investigation depths provided that modified equipment (viz. cables) is used. In the present paper, the application of deep electrical resistivity tomography (ERT) techniques is applied. ERT array of 21 electrodes, at a distance of 50 meters between them (total length 1000 meters) has been used in several studied areas located in the prefecture of Kavala (North Greece). In several cases near surface structure has been compared with VLF data. The aim of the survey was to study in detail the geological-hydrogeological structure the area of interest in order to suggest the best location for the construction of hydrowells with the most promising results. The 2D images of the geological structure down to the depth of at least 200 meters allowed the better understanding of the behaviour of layered geological formations, since in several cases resistivity values have been calibrated with data from pre-existing boreholes.

scholarly journals Electrical resistivity tomography applied to geologic, hydrogeologic, and engineering investigations at a former waste-disposal site

Geophysics ◽  
2006 ◽  
Vol 71 (6) ◽  
pp. B231-B239 ◽  
Author(s):  
Jonathan E. Chambers ◽  
Oliver Kuras ◽  
Philip I. Meldrum ◽  
Richard D. Ogilvy ◽  
Jonathan Hollands
Keyword(s):  
Electrical Resistivity ◽  
Electrical Resistivity Tomography ◽  
Site Investigation ◽  
High Resistivity ◽  
Potential Zone ◽  
Resistivity Tomography ◽  
L2 Norm ◽  
Resistivity Model ◽  
2D And 3D ◽  
2D Resistivity

A former dolerite quarry and landfill site was investigated using 2D and 3D electrical resistivity tomography (ERT), with the aims of determining buried quarry geometry, mapping bedrock contamination arising from the landfill, and characterizing site geology. Resistivity data were collected from a network of intersecting survey lines using a Wenner-based array configuration. Inversion of the data was carried out using 2D and 3D regularized least-squares optimization methods with robust (L1-norm) model constraints. For this site, where high resistivity contrasts were present, robust model constraints produced a more accurate recovery of subsurface structures when compared to the use of smooth (L2-norm) constraints. Integrated 3D spatial analysis of the ERT and conventional site investigation data proved in this case a highly effective means of characterizing the landfill and its environs. The 3D resistivity model was successfully used to confirm the position of the landfill boundaries, which appeared as electrically well-defined features that corresponded extremely closely to both historic maps and intrusive site investigation data. A potential zone of leachate migration from the landfill was identified from the electrical models; the location of this zone was consistent with the predicted direction of groundwater flow across the site. Unquarried areas of a dolerite sill were imaged as a resistive sheet-like feature, while the fault zone appeared in the 2D resistivity model as a dipping structure defined by contrasting bedrock resistivities.

Multi-scale hydrogeologic characterization of a leaky till–mantled fractured bedrock aquifer system

2015 ◽  
Vol 52 (12) ◽  
pp. 1945-1955 ◽  
Author(s):  
William G. Lukas ◽  
Don J. DeGroot ◽  
David W. Ostendorf ◽  
Erich S. Hinlein
Keyword(s):  
Hydraulic Conductivity ◽  
Coarse Grained ◽  
Small Scale ◽  
Data Sets ◽  
Aquifer System ◽  
Monitoring Wells ◽  
Fractured Bedrock ◽  
Decadal Scale ◽  
Fractured Bedrock Aquifer ◽  
Bedrock Aquifer

The paper presents hydrogeologic properties for a leaky till–mantled fractured bedrock aquifer system based on geophysical and hydraulic tests performed at a drumlin located in northeastern Massachusetts, USA. The site profile consists of a fractured bedrock aquifer overlain by a 30 m thick unweathered, coarse-grained till aquitard. Steady state, decadal scale, hydraulics varied little until seasonal irrigation pumping was initiated in recent years, causing a substantial annual drawdown in the aquifer and leakage from the overlying till. High frequency hydraulic head data sets collected in monitoring wells record the hydraulic response to the irrigation pumping. These data sets, together with results from small scale slug and purge tests performed in monitoring wells, are used to characterize the hydrogeologic behavior of this groundwater system. Geophysical logging performed in bedrock wells confirmed the presence of numerous flowing fractures. The large-scale continuum analysis of the fractured bedrock aquifer response to the irrigation pumping yields transmissivity values consistent with those determined from the small-scale, short-term purge test results. The low hydraulic conductivity till has a significant impact on the drawdown behavior of the fractured bedrock aquifer. Calibrated values from the collective data sets and analyses result in the following properties for the 30 m thick unweathered till: hydraulic conductivity K′ = 7.2 × 10−9 m/s, transmissivity T′ = 2.3 × 10−8 m2/s, and storativity S′ = 2.7 × 10−4, and for the underlying fractured bedrock aquifer: T = 6.5 × 10−6 m2/s with an average fracture aperture of 46 μm and hydraulic conductivity Kf = 1.3 × 10−3 m/s. These results should describe similar unweathered coarse-grained till–mantled fractured bedrock aquifer systems and provide useful data for preliminary analyses prior to any site-specific investigations.

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