Journal of Environmental Hydrology Volume 20 Paper 11 August 2012 1 The dependence on boreholes a... more Journal of Environmental Hydrology Volume 20 Paper 11 August 2012 1 The dependence on boreholes and hand-dug wells for water is increasing rapidly in Zaria, Nigeria, because of the inability of Water Works Department in the area to meet the water consumption requirement of the people. Almost all the boreholes and wells in the area fail to yield during dry seasons due to drastic reduction in groundwater table. This results in acute water shortage in the area. Virtually all the boreholes are located outside of valleys. Electrical resistivity tomography was conducted in the vicinity of two valleys in the area to delineate their underlying aquifer zones. The data were collected along five profiles laid perpendicular to the valleys’ strike. The data were tomographically inverted. Interpreted results show that the resistivity ranges of the bedrocks on either side of each of the valleys differ significantly which suggests sharp differences in the properties of the bedrocks on either side o...
The variation of electrical resistivity as a function of soil properties was used as a vital tool... more The variation of electrical resistivity as a function of soil properties was used as a vital tool to study groundwater contamination in the vicinity of some selected solid waste disposal sites in the municipal town of Zaria. The Abem Lund Imaging system with Terrameter SAS 4000 was used for the resistivity data measurements and the Res2dinv software was used for the processing and interpretations of the data. Due to the high conductivity of the contaminant plumes it was possible to delineate their pathways into the regolith and fractured aquifer environments. Resistivity data from inverted models obtained from profiles near monitoring wells, correlated well with electrical conductivity (EC) and total dissolved solid (TDS) values of water samples taken from theses wells. The inferred water resistivity and the soil resistivity obtained from the resistivity tomosections at depths of water table revealed that the samples, which were collected from hand dug wells whose depths are within ...
A Direct Current electrical resistivity survey was carried out in Unguwan Dosa open dumpsite in K... more A Direct Current electrical resistivity survey was carried out in Unguwan Dosa open dumpsite in Kaduna metropolis, North Western Nigeria. The dumpsite is the typical non-controlled waste facility that lack bottom liner. 8 vertical electrical soundings (VES) employing the Schlumberger electrode array were conducted with maximum electrode spacing of 100 m. Interpreted resistivities were obtained by iterative computer modeling of the apparent resistivity data. The VES data were plotted as pseudo and resistivity cross-sections in order to look at the spatial distribution of the contaminant plumes. The interpreted VES data measured inside the dumpsite showed contamination plumes as low zones with resistivity values ranging between 1 and 12.9 ohm-m extending from the surface down to the aquifer of shallow groundwater of less than 5 m. Calculated hydraulic conductivity ranges between m/s and for shallow subsurface layers of interpreted VES points located inside and outside the dumpsite. Th...
Remote Sensing Applications: Society and Environment, 2021
Abstract In this study, radiometric datasets which are best interpreted in conjunction with multi... more Abstract In this study, radiometric datasets which are best interpreted in conjunction with multispectral remote sensing data were applied in discriminating and classifying the lithologies of the Kebbi–Sokoto basement terrain for effective lithological mapping of the region. K/Th/U radiometric and Landsat-8 remote sensing data were enhanced through several processing techniques to display the characteristics of surface responses needed as input parameters in the classification of the surface rocks. Potassium radioelement concentration, Th/K channel ratio, normalization and ternary maps were produced using radiometric data while band combination and band ratio images were obtained from the Landsat-8 data. Several band ratios highlighted the major rock–forming minerals in the area such as feldspar, quartz, hematite, goethite, illite, kaolinite, biotite, amphibolite and dolomite. The major lithological expressions deduced from the combined data analysis namely; sandstone, felsic gneiss, clay, migmatite, granitoid and carbonates were used as representative classes to train the classification algorithm for the lithological interpretation. Supervised classification algorithm employing maximum likelihood classifier was used to obtain the lithological classification for basement rock units in the region. The classification results which were tested on band ratio b6/b2, b6/b7, b6/b5*b4/b5 image, b4/b2, b5/b6, b6/b7 image and b4/b2, b6/b7, b6/b5 image using a contingency table produced overall classification accuracy values of 79%, 92%, and 88% respectively. The classified images displayed quite similar geological feature discrimination with the radiometric ternary map and geological map of the area. The study emphasized the benefit of using geophysical and multispectral datasets to produce a more complete classification of the surficial Precambrian rocks exposed in the region.
Noninvasive geoelectrical subsurface characterisation provides screening of the earth medium to r... more Noninvasive geoelectrical subsurface characterisation provides screening of the earth medium to resolve complexity in subsurface geology caused by inhomogeneity of the overburden strata and bedrock...
The durability of roads is dependent on the proper screening of the variations in subsurface geol... more The durability of roads is dependent on the proper screening of the variations in subsurface geological characteristics and conditions through geo-engineering investigations and good construction practices. In this study, electrical resistivity tomography (ERT) technique was used to investigate the subsurface defects and potential failures along the substrate of Etioro-Akoko highway, Ondo State, southwestern Nigeria. Results of the inverse model resistivity sections generated for the two investigated traverses showed four distinct subsurface layers. The shallow clayey topsoil, weathered layer, and partially weathered/fractured bedrock have resistivity values ranging from 4–150 ohm-m, 10–325 ohm-m, and 205–800 ohm-m, with thickness values of 0–2 m, 0.5–12.5 m, and less than few meters to > 24 m, respectively. The fresh bedrock is characterised by resistivity generally in excess of 1000 ohm-m. The bedrock mirrored gently to rapidly oscillating bedrock troughs and relatively incline...
Electrical resistivity tomography (ERT) was used for delineating significant subsurface hydrogeol... more Electrical resistivity tomography (ERT) was used for delineating significant subsurface hydrogeological features for sustainable groundwater development in Etioro-Akoko area, Southwestern Nigeria. This study was necessitated by challenges posed on groundwater supplies from wells and boreholes in Etioro-Akoko and the neighbouring fast growing towns and villages. Field data were acquired over the area with ABEM Lund Resistivity Imaging System and were subsequently processed and inverted through RES2DINVx64 software. Results showed four distinct subsurface layers: topsoil, weathered layer, fractured bedrock and fresh bedrock (basal unit). Localised bedrock depressions occasioned by fracturing and deep weathering of less stable bedrock minerals were delineated with resistivity and thickness values ranging from 50 to 650 Ωm and 12 to ---gt--- 25 m, respectively. The localised depressions mirrored uneven bedrock topography and served as the preferential groundwater storage and hydrogeolog...
NRIAG Journal of Astronomy and Geophysics, Jan 21, 2021
Noninvasive geoelectrical subsurface characterisation provides screening of the earth medium to r... more Noninvasive geoelectrical subsurface characterisation provides screening of the earth medium to resolve complexity in subsurface geology caused by inhomogeneity of the overburden strata and bedrock architectures. The subsurface geological, hydrogeophysical and engineering con�ditions of Etioro-Akoko, southwestern Nigeria, were investigated using electrical resistivity tomography (ERT). This was aimed at unravelling the hydrogeodynamic and litho-structural complexity that are responsible for low groundwater yield in wells/boreholes and foundation failures. Field 2D resistivity data sets of the study area were inverted and used to produce geotomographic models for detailed insights into the complex subsurface geological setting. Results of the 2D resistivity inverted models showed three to four distinct layers; the topsoil, weathered layer, partially weathered/fractured bedrock and fresh bedrock. Bedrock structures occasioned by fracturing and deep weathering of the bedrock were delineated with resistivities and thicknesses ranging from 40 to 950 Ωm and 10–25 m, respectively. The fracture systems; F1, F2, F3, F4 and F5 in NW-SE, NNW-SSE, NE-SW and ENE-WSW orientations act as the major groundwater collecting centres in the area. The orientations and geometries of these geologic features are the manifestations of structural deformation of the underlying geology. Fourteen hand-dug well and four borehole points were proposed based on the ERT results. Conversely, the localised bedrock structures and oscillating bedrock topography were suggestive of poten�tial threats to the foundations of engineering structures in the studied area. Reinforcement of concrete foundations at certain sites where ERT suggested that the underlying strata were not capable of bearing loads was recommended as well. This study has offered a detailed under�standing of the subsurface geological disposition for sustainable groundwater development and siting of durable civil engineering structures in the studied area and other areas with typical complex geological settings.
The durability of roads is dependent on the proper screening of the variations in subsurface geol... more The durability of roads is dependent on the proper screening of the variations in subsurface geological characteristics and conditions through geo-engineering investigations and good construction practices. In this study, electrical resistivity tomography (ERT) technique was used to investigate the subsurface defects and potential failures along the substrate of Etioro-Akoko highway, Ondo State, southwestern Nigeria. Results of the inverse model resistivity sections generated for the two investigated traverses showed four distinct subsurface layers. The shallow clayey topsoil, weathered layer, and partially weathered/fractured bedrock have resistivity values ranging from 4-150 ohm-m, 10-325 ohm-m, and 205-800 ohm-m, with thickness values of 0-2 m, 0.5-12.5 m, and less than few meters to > 24 m, respectively. The fresh bedrock is characterised by resistivity generally in excess of 1000 ohm-m. The bedrock mirrored gently to rapidly oscillating bedrock troughs and relatively inclined deep penetrating multiple fractures: F1-F'1, F2-F'2 and F3-F'3, with floater in-between the first two fractures. These delineated subsurface characteristic features were envisaged as potential threats to the pavement of the highway. Pavement failures in the area could be attributed to the incompetent clayey sub-base/ substrate materials and the imposed stresses on the low load-bearing fractured bedrock and deep weathered troughs by heavy traffics. Anticipatory construction designs that included the use of competent sub-base materials and bridges for the failed segments and fractured zones along the highway, respectively, were recommended.
Journal of Environmental Hydrology Volume 20 Paper 11 August 2012 1 The dependence on boreholes a... more Journal of Environmental Hydrology Volume 20 Paper 11 August 2012 1 The dependence on boreholes and hand-dug wells for water is increasing rapidly in Zaria, Nigeria, because of the inability of Water Works Department in the area to meet the water consumption requirement of the people. Almost all the boreholes and wells in the area fail to yield during dry seasons due to drastic reduction in groundwater table. This results in acute water shortage in the area. Virtually all the boreholes are located outside of valleys. Electrical resistivity tomography was conducted in the vicinity of two valleys in the area to delineate their underlying aquifer zones. The data were collected along five profiles laid perpendicular to the valleys’ strike. The data were tomographically inverted. Interpreted results show that the resistivity ranges of the bedrocks on either side of each of the valleys differ significantly which suggests sharp differences in the properties of the bedrocks on either side o...
The variation of electrical resistivity as a function of soil properties was used as a vital tool... more The variation of electrical resistivity as a function of soil properties was used as a vital tool to study groundwater contamination in the vicinity of some selected solid waste disposal sites in the municipal town of Zaria. The Abem Lund Imaging system with Terrameter SAS 4000 was used for the resistivity data measurements and the Res2dinv software was used for the processing and interpretations of the data. Due to the high conductivity of the contaminant plumes it was possible to delineate their pathways into the regolith and fractured aquifer environments. Resistivity data from inverted models obtained from profiles near monitoring wells, correlated well with electrical conductivity (EC) and total dissolved solid (TDS) values of water samples taken from theses wells. The inferred water resistivity and the soil resistivity obtained from the resistivity tomosections at depths of water table revealed that the samples, which were collected from hand dug wells whose depths are within ...
A Direct Current electrical resistivity survey was carried out in Unguwan Dosa open dumpsite in K... more A Direct Current electrical resistivity survey was carried out in Unguwan Dosa open dumpsite in Kaduna metropolis, North Western Nigeria. The dumpsite is the typical non-controlled waste facility that lack bottom liner. 8 vertical electrical soundings (VES) employing the Schlumberger electrode array were conducted with maximum electrode spacing of 100 m. Interpreted resistivities were obtained by iterative computer modeling of the apparent resistivity data. The VES data were plotted as pseudo and resistivity cross-sections in order to look at the spatial distribution of the contaminant plumes. The interpreted VES data measured inside the dumpsite showed contamination plumes as low zones with resistivity values ranging between 1 and 12.9 ohm-m extending from the surface down to the aquifer of shallow groundwater of less than 5 m. Calculated hydraulic conductivity ranges between m/s and for shallow subsurface layers of interpreted VES points located inside and outside the dumpsite. Th...
Remote Sensing Applications: Society and Environment, 2021
Abstract In this study, radiometric datasets which are best interpreted in conjunction with multi... more Abstract In this study, radiometric datasets which are best interpreted in conjunction with multispectral remote sensing data were applied in discriminating and classifying the lithologies of the Kebbi–Sokoto basement terrain for effective lithological mapping of the region. K/Th/U radiometric and Landsat-8 remote sensing data were enhanced through several processing techniques to display the characteristics of surface responses needed as input parameters in the classification of the surface rocks. Potassium radioelement concentration, Th/K channel ratio, normalization and ternary maps were produced using radiometric data while band combination and band ratio images were obtained from the Landsat-8 data. Several band ratios highlighted the major rock–forming minerals in the area such as feldspar, quartz, hematite, goethite, illite, kaolinite, biotite, amphibolite and dolomite. The major lithological expressions deduced from the combined data analysis namely; sandstone, felsic gneiss, clay, migmatite, granitoid and carbonates were used as representative classes to train the classification algorithm for the lithological interpretation. Supervised classification algorithm employing maximum likelihood classifier was used to obtain the lithological classification for basement rock units in the region. The classification results which were tested on band ratio b6/b2, b6/b7, b6/b5*b4/b5 image, b4/b2, b5/b6, b6/b7 image and b4/b2, b6/b7, b6/b5 image using a contingency table produced overall classification accuracy values of 79%, 92%, and 88% respectively. The classified images displayed quite similar geological feature discrimination with the radiometric ternary map and geological map of the area. The study emphasized the benefit of using geophysical and multispectral datasets to produce a more complete classification of the surficial Precambrian rocks exposed in the region.
Noninvasive geoelectrical subsurface characterisation provides screening of the earth medium to r... more Noninvasive geoelectrical subsurface characterisation provides screening of the earth medium to resolve complexity in subsurface geology caused by inhomogeneity of the overburden strata and bedrock...
The durability of roads is dependent on the proper screening of the variations in subsurface geol... more The durability of roads is dependent on the proper screening of the variations in subsurface geological characteristics and conditions through geo-engineering investigations and good construction practices. In this study, electrical resistivity tomography (ERT) technique was used to investigate the subsurface defects and potential failures along the substrate of Etioro-Akoko highway, Ondo State, southwestern Nigeria. Results of the inverse model resistivity sections generated for the two investigated traverses showed four distinct subsurface layers. The shallow clayey topsoil, weathered layer, and partially weathered/fractured bedrock have resistivity values ranging from 4–150 ohm-m, 10–325 ohm-m, and 205–800 ohm-m, with thickness values of 0–2 m, 0.5–12.5 m, and less than few meters to > 24 m, respectively. The fresh bedrock is characterised by resistivity generally in excess of 1000 ohm-m. The bedrock mirrored gently to rapidly oscillating bedrock troughs and relatively incline...
Electrical resistivity tomography (ERT) was used for delineating significant subsurface hydrogeol... more Electrical resistivity tomography (ERT) was used for delineating significant subsurface hydrogeological features for sustainable groundwater development in Etioro-Akoko area, Southwestern Nigeria. This study was necessitated by challenges posed on groundwater supplies from wells and boreholes in Etioro-Akoko and the neighbouring fast growing towns and villages. Field data were acquired over the area with ABEM Lund Resistivity Imaging System and were subsequently processed and inverted through RES2DINVx64 software. Results showed four distinct subsurface layers: topsoil, weathered layer, fractured bedrock and fresh bedrock (basal unit). Localised bedrock depressions occasioned by fracturing and deep weathering of less stable bedrock minerals were delineated with resistivity and thickness values ranging from 50 to 650 Ωm and 12 to ---gt--- 25 m, respectively. The localised depressions mirrored uneven bedrock topography and served as the preferential groundwater storage and hydrogeolog...
NRIAG Journal of Astronomy and Geophysics, Jan 21, 2021
Noninvasive geoelectrical subsurface characterisation provides screening of the earth medium to r... more Noninvasive geoelectrical subsurface characterisation provides screening of the earth medium to resolve complexity in subsurface geology caused by inhomogeneity of the overburden strata and bedrock architectures. The subsurface geological, hydrogeophysical and engineering con�ditions of Etioro-Akoko, southwestern Nigeria, were investigated using electrical resistivity tomography (ERT). This was aimed at unravelling the hydrogeodynamic and litho-structural complexity that are responsible for low groundwater yield in wells/boreholes and foundation failures. Field 2D resistivity data sets of the study area were inverted and used to produce geotomographic models for detailed insights into the complex subsurface geological setting. Results of the 2D resistivity inverted models showed three to four distinct layers; the topsoil, weathered layer, partially weathered/fractured bedrock and fresh bedrock. Bedrock structures occasioned by fracturing and deep weathering of the bedrock were delineated with resistivities and thicknesses ranging from 40 to 950 Ωm and 10–25 m, respectively. The fracture systems; F1, F2, F3, F4 and F5 in NW-SE, NNW-SSE, NE-SW and ENE-WSW orientations act as the major groundwater collecting centres in the area. The orientations and geometries of these geologic features are the manifestations of structural deformation of the underlying geology. Fourteen hand-dug well and four borehole points were proposed based on the ERT results. Conversely, the localised bedrock structures and oscillating bedrock topography were suggestive of poten�tial threats to the foundations of engineering structures in the studied area. Reinforcement of concrete foundations at certain sites where ERT suggested that the underlying strata were not capable of bearing loads was recommended as well. This study has offered a detailed under�standing of the subsurface geological disposition for sustainable groundwater development and siting of durable civil engineering structures in the studied area and other areas with typical complex geological settings.
The durability of roads is dependent on the proper screening of the variations in subsurface geol... more The durability of roads is dependent on the proper screening of the variations in subsurface geological characteristics and conditions through geo-engineering investigations and good construction practices. In this study, electrical resistivity tomography (ERT) technique was used to investigate the subsurface defects and potential failures along the substrate of Etioro-Akoko highway, Ondo State, southwestern Nigeria. Results of the inverse model resistivity sections generated for the two investigated traverses showed four distinct subsurface layers. The shallow clayey topsoil, weathered layer, and partially weathered/fractured bedrock have resistivity values ranging from 4-150 ohm-m, 10-325 ohm-m, and 205-800 ohm-m, with thickness values of 0-2 m, 0.5-12.5 m, and less than few meters to > 24 m, respectively. The fresh bedrock is characterised by resistivity generally in excess of 1000 ohm-m. The bedrock mirrored gently to rapidly oscillating bedrock troughs and relatively inclined deep penetrating multiple fractures: F1-F'1, F2-F'2 and F3-F'3, with floater in-between the first two fractures. These delineated subsurface characteristic features were envisaged as potential threats to the pavement of the highway. Pavement failures in the area could be attributed to the incompetent clayey sub-base/ substrate materials and the imposed stresses on the low load-bearing fractured bedrock and deep weathered troughs by heavy traffics. Anticipatory construction designs that included the use of competent sub-base materials and bridges for the failed segments and fractured zones along the highway, respectively, were recommended.
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