Geoelectrical Evaluation of Groundwater Occurrence in Anwai, Delta State, Nigeria

The purpose of carrying out this survey is to determine the groundwater occurrence in Anwai, Nigeria. Eight geoelectric soundings were conducted using the Schlumberger configuration. The data obtained were interpreted using two layer model. The result revealed the presence of five geoelectric layers made up of topsoil laterite, clay-clayey sand, fine-medium grain sand, coarse sand, medium coarse sand and very coarse sand. The fifth layer with a depth range of 33.4 to 47.2 m and resistivity range of between 1512 and 3294 Wm is identified as the aquifer layer from which groundwater can be sourced. It is deduced from this survey that groundwater development is viable in the area. Keywords: Groundwater, Geoelectric, Aquifer, Electrical Resistivity, Schlumberger Configuratio

Mapping of aquifer hydraulic properties in Ogbeje and Umeghe in Abraka, Delta State Nigeria: insights from geophysical and hydrogeological methods

Vertical Electrical Sounding (VES), Pumping test, well logging and grain size analysis were conducted with the aim of studying the subsurface geophysical formation in order to determine aquifer characteristics such as hydraulic conductivity, transmissivity and other parameters for groundwater exploration purposes around Ogbeje and Umeghe, Abraka Delta State. Nine (9) VES stations were occupied and the results obtained from the computer iterations suggest 4 to 5 geoelectric layers. The aquiferous layers wwerefound at a depth ranging from 20.0 m – 38.3 m with resistivity ranging from 2200 ?m to 8500 ?m and thickness varying between 6.7 and 20.0 m. The VES study reveals the possibility of having a maximum drill depth the o water table of about 38 m. The results obtained from the pumping test and well logginwereas used to estimate the transmissivity value of T = 0.0722 m2/min, storativity S = 0.00063, specific capacity of the well = 0.39 m2/min and hydraulic conductivity, K= 8.5 m/day while the result from the grain size analysis gave hydraulic conductivity as Kmin= 12.96 m/d to Kmax = 26.96 m/d respectively. Thus, these results indicate that the aquifer is capable of proda ucing sufficient amount of water for both domestic and industrial purposes for the people in the area

Geophysical and geotechnical assessment of Obiaruku-Agbor road failure in Western Niger-Delta, Nigeria

A geophysical and geotechnical survey was carried out along the Obiaruku-Agbor Expressway in Delta State, Nigeria to determine the causes of its deterioration. The study used a 2D electrical resistivity approach using the ABEM SAS 1000 Terrameter and yielded subsurface resistivity values ranging from 5.12 Ohm-m to 4418 Ohm-m. The geo-electric resistivity result showed that the base, sub-base, infill and embarkment soil types range from an interchange of clay,sandyclay, clay sand, fine sand and coarse sand.The high percentage of low-resistivity soil indicated that the building materials were not appropriate. Using soil samples, gathered for various geotechnical parameter tests for surface sub-base and base materials in accordance with British standards, the geotechnical characteristics of the research sites were ascertained. The findings show that A-2 and A-7 soil types are the most common types. The soils from the stable sections have a higher specific gravity (2.59-2.89) and a smaller amount of clay (16.9 %) than the soils from the failed portions of A-7-6 which suggests substandard sub-grade materials. These soils correspond to A-2-6 on the AASHTO classification system. The bulk of soils from failed sections had significant values of linear shrinkage (> 8%), a large proportion of fine particles (> 40%), and pore water pressure occurred as a result in a loss of soil index strength. The majority of fines particles in lateritic soils, low California bearing ratio (08–63% un-soaked), intermediate and high OMC above guideline for most soil samples (07.4–20.1), maximum dry density (MDD) (<2000 kg/m3), and liquid limit (20.9–58.7) are the main causes of the observed degree of instability. Poor geotechnical characteristics in the lateritic and sub-grade soils of failed sections imply that they should not be used as sub-grade materials in other engineering works, let alone in the building of new roads. It is stressed that lateritic soils are crucial for precise sub-grade soil assessment in detail sampling for highways. When these values were compared to the standard, it became clear that the main reasons for road collapse were thin pavement, inadequate drainage, water-logged sands, low-quality infill, incompetent clayey materials beneath the built road, and neglect. It is consequently advised that a well-designed, organized drainage system be built and that the soils be stabilized or replaced with materials that adhere to standards.The results of this inquiry will be useful in the repair and rehabilitation of the road's deteriorating sections and it is recommended that a thorough record of this study be kept for future reference

Hydrogeophysical and hydrogeological investigations of groundwater resources in Delta Central, Nigeria

AbstractAn electrical resistivity survey, down-hole logging and pumping test were conducted in Delta Central District of Nigeria to determine the groundwater potential and aquifer characteristics of the study area. Twenty vertical electrical soundings of the Schlumberger configuration were performed with an ABEM SAS 1000 Terrameter. The geoelectric data obtained were interpreted with partial curve matching and computer iteration using RESIST software. The results showed the presence of four geoelectric layers comprising loamy–sandy topsoil, clay, fine sand and coarse sand. The investigation also revealed the presence of a confined aquifer in the area, with resistivity values of 869.1–8704.1Ωm, while the depth of the aquifer ranged between 20.2 and 25.4m. The average values of the groundwater characteristics obtained were 0.026mS/m for electrical conductivity, 25.75mg/m3 for total dissolved solids, 0.022m2/min for transmissivity and 0.000133 for storativity. Comparison of these values with international standards indicated that the water in the aquifer is of good quality and that the yield could withstand heavy pumping. It is therefore recommended that a good water scheme be established to serve the people of the area, including its surrounding towns