scholarly journals Use of Vertical Electrical Sounding for Delineating Groundwater Contamination in the Uplands Wadi Rasyan, Taiz, Yemen.

2011 ◽  
Vol 22 (2) ◽  
pp. 131-154
Author(s):  
Hamza A. Ibrahim Hamza A. Ibrahim
Keyword(s):  
Groundwater Contamination ◽  
Fresh Water ◽  
Cross Sections ◽  
Apparent Resistivity ◽  
Industrial Wastes ◽  
Near Surface ◽  
Subsurface Layers ◽  
Electrical Sounding ◽  
Depth Sounding ◽  
Growing Population

Fresh water is becoming increasingly scarce in Taiz city, Yemen, partly due to a growing population and in part due to pollution of near surface aquifers by municipal and industrial wastes. Electrical depth sounding has been found to be powerful tool to delineate subsurface contaminated zones. The measured apparent resistivity and 1D inversion models have been used to construct apparent maps and 2D geoelectrical cross-sections displaying the variation of resistivity of the subsurface layers.

scholarly journals New Semi Quantitative Approach for Interpreting Vertical Electrical Sounding (VES) Measurements by Using Fractal Modeling Technique, Case Study from Khanasser Valley, Northern Syria

2021 ◽  
Vol 60 (3) ◽  
pp. 211-228
Author(s):  
Jamal Asfahani
Keyword(s):  
Cross Sections ◽  
Apparent Resistivity ◽  
Quantitative Approach ◽  
Vertical Electrical Sounding ◽  
Modeling Technique ◽  
Fractal Approach ◽  
Fractal Modeling ◽  
Electrical Sounding ◽  
Break Points

Fractal modeling technique, with adapting the concentration-number (C-N) model and the threshold break points concept is newly proposed to interpret vertical electrical sounding (VES) measurements distributed along a given profile. New semi quantitative approach is consequently proposed to rapidly differentiate between different apparent resistivity populations, where 2D semi quantitative interpretation and a primary geological analysis could be constructed. The new technique is practiced and tested on a case study taken from Khanasser Valley, Northern Syria, where different selected profiles (LP1, LP2, LP3, and TP5) are interpreted. The availability and the feasibility of the proposed approached are confirmed and approved through the different comparisons between the multi fractal established cross sections and the traditional 1D VES interpretation models. It is recommended to routinely use this new proposed fractal approach in the geoelectrical researches for interpreting VES measurements distributed along a given profile.

GEOPHYSICAL INVESTIGATION OF GROUNDWATER CONTAMINATION USING DC RESISTIVITY TECHNIQUE AT THE MALE HOSTEL OF ISA KAITA COLLEGE OF EDUCATION DUTSIN-MA, KATSINA STATE, NIGERIA

2021 ◽  
Vol 4 (4) ◽  
pp. 547-560
Author(s):  
Aniefiok Akpaneno ◽  
S. Abdulwahab
Keyword(s):  
Groundwater Contamination ◽  
College Of Education ◽  
Signal Averaging ◽  
Geophysical Investigation ◽  
Dumping Site ◽  
Vertical Electrical Soundings ◽  
Electrical Conductivities ◽  
Electrical Sounding ◽  
Electrical Soundings ◽  
Sas Model

A geophysical investigation involving Vertical Electrical Sounding (VES) using the Schlumberger array was carried out at the Isa Kaita College of Education specifically at the Male Hostel. The aim of the investigation is to explore the groundwater contamination of the area with the objectives: to determine the depth to basement of the study area, to determine the aquifer thickness, to determine the depth to aquifer, to determine the conductivity of the aquifer and to determine the thickness of topsoil and its variation in resistivity. A total of four (4) vertical electrical soundings were carried out using Schlumberger configuration. Terrameter signal averaging system (SAS) model 300 was the instrument used. The survey area is dominated by mainly four layers, namely: Topsoil, Weathered basement, fractured basement. The value of VES 03 and VES 04 have high electrical conductivities which likely shows they are contaminated, The topsoil resistivity along the profile ranges from approximately 1 to 154, The depth to basement (basement topography) Varies from 4.94 m to 7.59 m, The thickness of aquifer range from  1 m to 6.8 m.  Therefore VES 02 has high Potential for groundwater because it has retaining capacity and good aquifer thickness and is therefore recommended for borehole establishment. It is recommended that the management of Isa Kaita College of Education should provide a concrete dumping site to avoid leaching of waste in ground thereby contaminating the groundwater.

Sea Water Intrusion Monitoring on the Sendangbiru of the Southern Malang Coastal Area based on Geoelectrical Resistivity Data

2021 ◽  
Vol 14 (9) ◽  
pp. 43-48
Author(s):  
Sunaryo .
Keyword(s):  
Data Acquisition ◽  
Cross Section ◽  
Seawater Intrusion ◽  
Cross Sections ◽  
Sea Water ◽  
Salt Water ◽  
Sea Water Intrusion ◽  
Electrical Sounding ◽  
Geoelectrical Resistivity ◽  
Intrusion Layer

The study was conducted with the objective to distinguish the presence of seawater intrusion layer or salt-water aquifer distribution along the data acquisition line at the locations. Data acquisition was conducted by using the Wenner-Schumberger configuration of geoelectrical resistivity. From this research, 4 lines and 4 points of vertical electrical sounding (VES) data for every line were obtained with the distance between electrode a as 10m. Based on the data processing, obtained depth up to 120m with the smallest resistivity value is 0.02Ωm and the largest is 6764.52Ωm. To make the distribution of resistivity values along the path line of the study, cross sections were made until a depth of 120m. Based on the cross-section, the low resistivity value (less than 1.5 Ωm) that interpreted as a seawater intrusion layer or salt water aquifer distribution is located at varying depths. There are intrusions for the SB1 cross section, there is an intrusion at a depth of 6m-7m as far as 10m, at a depth of 6m-8m as far as 10m for the SB2 cross section and at a depth of 22m - 26m as far as 25m for the SB3 cross section.

Ocean Salinity Aspects of the Ningaloo Niño

2021 ◽  
pp. 1
Author(s):  
Yaru Guo ◽  
Yuanlong Li ◽  
Fan Wang ◽  
Yuntao Wei
Keyword(s):  
Fresh Water ◽  
Large Scale ◽  
Southern Oscillation ◽  
Regional Climate ◽  
Ocean Model ◽  
Sea Surface ◽  
Sea Surface Salinity ◽  
Surface Salinity ◽  
Near Surface ◽  
Ocean Salinity

AbstractNingaloo Niño – the interannually occurring warming episode in the southeast Indian Ocean (SEIO) – has strong signatures in ocean temperature and circulation and exerts profound impacts on regional climate and marine biosystems. Analysis of observational data and eddy-resolving regional ocean model simulations reveals that the Ningaloo Niño/Niña can also induce pronounced variability in ocean salinity, causing large-scale sea surface salinity (SSS) freshening of 0.15–0.20 psu in the SEIO during its warm phase. Model experiments are performed to understand the underlying processes. This SSS freshening is mutually caused by the increased local precipitation (~68%) and enhanced fresh-water transport of the Indonesian Throughflow (ITF; ~28%) during Ningaloo Niño events. The effects of other processes, such as local winds and evaporation, are secondary (~18%). The ITF enhances the southward fresh-water advection near the eastern boundary, which is critical in causing the strong freshening (> 0.20 psu) near the Western Australian coast. Owing to the strong modulation effect of the ITF, SSS near the coast bears a higher correlation with the El Niño-Southern Oscillation (0.57, 0.77, and 0.70 with Niño-3, Niño-4, and Niño-3.4 indices, respectively) than sea surface temperature (-0.27, -0.42, and -0.35) during 1993-2016. Yet, an idealized model experiment with artificial damping for salinity anomaly indicates that ocean salinity has limited impact on ocean near-surface stratification and thus minimal feedback effect on the warming of Ningaloo Niño.

scholarly journals Evaluation of Forecasts of a Convectively Generated Bore Using an Intensively Observed Case Study from PECAN

2018 ◽  
Vol 146 (9) ◽  
pp. 3097-3122 ◽  
Author(s):  
Aaron Johnson ◽  
Xuguang Wang ◽  
Kevin R. Haghi ◽  
David B. Parsons
Keyword(s):  
Cross Sections ◽  
Turbulent Mixing ◽  
Weather Research And Forecasting ◽  
Cold Pool ◽  
Model Errors ◽  
Near Surface ◽  
Cold Pools ◽  
Convection Model

Abstract This paper presents a case study from an intensive observing period (IOP) during the Plains Elevated Convection at Night (PECAN) field experiment that was focused on a bore generated by nocturnal convection. Observations from PECAN IOP 25 on 11 July 2015 are used to evaluate the performance of high-resolution Weather Research and Forecasting Model forecasts, initialized using the Gridpoint Statistical Interpolation (GSI)-based ensemble Kalman filter. The focus is on understanding model errors and sensitivities in order to guide forecast improvements for bores associated with nocturnal convection. Model simulations of the bore amplitude are compared against eight retrieved vertical cross sections through the bore during the IOP. Sensitivities of forecasts to microphysics and planetary boundary layer (PBL) parameterizations are also investigated. Forecasts initialized before the bore pulls away from the convection show a more realistic bore than forecasts initialized later from analyses of the bore itself, in part due to the smoothing of the existing bore in the ensemble mean. Experiments show that the different microphysics schemes impact the quality of the simulations with unrealistically weak cold pools and bores with the Thompson and Morrison microphysics schemes, cold pools too strong with the WDM6 and more accurate with the WSM6 schemes. Most PBL schemes produced a realistic bore response to the cold pool, with the exception of the Mellor–Yamada–Nakanishi–Niino (MYNN) scheme, which creates too much turbulent mixing atop the bore. A new method of objectively estimating the depth of the near-surface stable layer corresponding to a simple two-layer model is also introduced, and the impacts of turbulent mixing on this estimate are discussed.

scholarly journals Modelling of Pollution Transport with Sediment on the Example of the Widawa River

2013 ◽  
Vol 39 (2) ◽  
pp. 29-43 ◽  
Author(s):  
Robert Kasperek ◽  
Marian Mokwa ◽  
Mirosław Wiatkowski
Keyword(s):  
Grain Size ◽  
Cross Sections ◽  
Sample Volume ◽  
Industrial Wastes ◽  
Phosphorus Concentration ◽  
Pollution Transport ◽  
Sediment Grain Size ◽  
Run Off ◽  
Odra River ◽  
Geochemical Analyses

Abstract The aim of the study was to determine the contamination transport condition with sediment in the Widawa River, which inflows to the Odra River below Wrocław city. The transport simulations have been performed by means of HEC-RAS model, which was calibrated. Study and geochemical analyses indicate that pollutions are cumulated mainly in sediment of grain size, less than 0,20 mm. It was stated that the main sources of contaminations occurring in the Widawa River bottoms are: superficial run-off, municipal and industrial wastes. Sediment bed quality from the Widawa River in selected cross-sections has been analyzed. Samples of suspended load were collected and divided into eight fractions, for which the phosphorus concentration P was calculated. Deposit particles less than 0,20 mm contained most phosphorus, i.e. 73% (3,52 ppm), and particles greater than 0,20 mm about 27% (1,30 ppm) for the whole sample volume. Relationship between the phosphorus concentration P and the sediment grain size was determined. Analysis showed that the initiation of contamination-sediment suspension in the Widawa River is well described by Engelund criterion. Simulations of the migration of pollutions together with deposits in the Widawa River showed that during average flow discharge, the transport intensity of pollution was equal 2 mg/s, and sediments 6 kg/s. In the present work the water quality of the Widawa River has been also presented.

scholarly journals Strength Attainment of Geopolymer Concrete with GGBS at Ambient Curing

2019 ◽  
Vol 9 (2S2) ◽  
pp. 56-59
Keyword(s):  
Tensile Strength ◽  
Ambient Temperature ◽  
Sodium Hydroxide ◽  
Cross Sections ◽  
Strength Properties ◽  
Industrial Wastes ◽  
Mix Design ◽  
Geopolymer Concrete ◽  
Ambient Curing ◽  
Test Result

Geopolymer concrete plays a major role in concrete industry by replacing cement and using the industrial wastes. In this study, the cement is completely replaced by GGBS and strength properties are analyzed. An M30 mix design is prepared and the specimens are cast and tested. For this, sodium hydroxide and sodium silicate are used as activator and its ratio is fixed as 1:2.5. Sodium hydroxide of 12 molarity, 550kg/m3 of GGBS is used in the study. Admixture La Hypercrete S25 (HTS code 38244090) is added in the mix by 1% of weight of GGBS to obtain the required workability. For compression study, cubes in 100 mm size are cast. Cylinders with 100mm dia and 200mm height are tested for splitting tensile strength and beam specimens of 500mm long and 100mm cross sections were cast for determining the flexure behaviour. The beams are subjected to ambient curing and tested at 3, 7, 14, 28 and 56 days. The test result shows that there is a gradual increment in all the strengths from 3 to 56 days and it proves that geopolymer concrete with GGBS cured at ambient temperature performs well in the strength properties.

scholarly journals Assessment of 2-D resistivity structures using 1-D inversion

Geophysics ◽  
1991 ◽  
Vol 56 (6) ◽  
pp. 874-883 ◽  
Author(s):  
L. P. Beard ◽  
F. D. Morgan
Keyword(s):  
Cross Section ◽  
Cross Sections ◽  
Apparent Resistivity ◽  
Inversion Process ◽  
Square Prism ◽  
Contour Lines ◽  
The Cross ◽  
Schlumberger Array ◽  
Wenner Array

Schlumberger and Wenner array resistivity soundings over 2-D resistivity structures are interpreted using apparent resistivity pseudosections and cross‐sections constructed from 1-D inversions in order to determine the effectiveness of 1-D interpretations over such structures. Cross‐sections contoured from resistivities of inverted “layers” show distinct differences from the apparent resistivity pseudosections and may be used as interpretational aids. Contour lines in the cross‐sections locate the horizontal interfaces of the 2-D structures quite well. The vertically oriented segments of the cross‐section contours are relatively undistorted in the inversion process and are similar to the vertically oriented portions of contours in the apparent resistivity pseudosection. A simple, empirically determined formula is used to separate the sections into resistive and conductive zones and helps to define the geometry of the anomaly. In order to apply the formula, it is necessary to know whether the target is a relative conductor or a relative resistor. Except for the case of a square prism, the Schlumberger array appears to hold advantages over the Wenner in qualitatively assessing an anomaly. The primary drawback of the Wenner array is that its expanding potential electrodes create false anomalous zones and complicate interpretation. As might be expected, structures with long horizontal interfaces, i.e. those more nearly 1-D, yield the most accurate interpretations.

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