Geosciences-Scholarly Publications

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Browsing Geosciences-Scholarly Publications by Subject "Aquifer"

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  • Item
    Open Access
    Application of geoelectrical and chemical methods for groundwater assessment in Isheri-North, Ogun state, Nigeria
    (Journal of Science and Technology (Ghana), 2015) Adeoti, L; Bello, M.A; Olatinsu, O.B; Adiat, K.A.N
    Geoelectrical investigation and chemical analyses were carried out at Isheri North area of Ogun State in order to assess the groundwater quality at shallow depth and its deep potential zone for groundwater development. The study area has been selected for investigation due to infiltration of the polluted Ogun River. Forty-three (43) Schlumberger Vertical Electrical Soundings (VES) and chemical analyses of water samples from one hand dug well and two shallow boreholes in the study area were carried out. Four to five geoelectric layers which correspond to top soil, clayey sand, sandy clay, clay and sand were delineated. The longitudinal conductance values (0.02 - 0.106mhos) of the topsoil in the area reveal its poor to weak protective capacity, thus exposing the underlying clayey sand to contamination as reflected from its resistivity values ranging from 4.8-15.1Ωm. This low resistivity zone at shallow depth (3 – 26m), occasioned by infiltration, was further ascertained by high values of conductivity, turbidity, total hardness, TDS, Cl, Fe, and Mn ions in the analyzed water samples taken at depth ranges from 9 – 16m. The results of the analyzed water samples from this shallow zone are beyond international standards for drinking water. The underlying clay resistivity values ranged between 1.9 - 6.1Ωm and thickness varied from 50.8 - 100.5m. This acts as the seal for the underlying aquifer (sand layer). The resistivity of the sand layer varied from 91.7-159Ωm with a depth interval of 101.7-109.4m and 73.4-82.3m in VES 1 and VES 14 respectively. This constitutes the deep aquifer units in the study area. The longitudinal conductance values of the overburden above the profound aquifer units varied between 10.5-33.0 mhos and are indicative of very good to excellent protective capacity rating. Thus, the underlying deep aquifer units are well protected from being contaminated.
  • Item
    Open Access
    Extent and distribution of groundwater resources in parts of Anambra State, Southeastern, Nigeria.
    (Journal of Applied Sciences and Environmental Management, 2007) Nfor, B.N; Olobaniyi, S.B; Ogala, J.E
    The extent and distribution of groundwater resources in parts of Anambra State, Nigeria has been investigated. The results show that the study area is directly underlain by four different geological formations including, Alluvial Plain Sands, Ogwashi-Asaba Formation, Ameki/Nanka Sands and Imo Shale, with varying water storage and yielding capacities. Borehole depths within the Alluvial Plain Sands are shallow (5-30m) yet the sands are excellent aquifers with high yields (3-5 litres/sec) especially along the Anambra West – Onitsha - Ogbaru L.G.A. axis. Elsewhere the yield is low (about 0.5litres/sec) and may dry up at peak dry season periods. The Ogwashi-Asaba Formation occurs in a north-southerly trend and underlies Ekwusigo, Nnewi North and South and Ihiala Local Government Areas. This formation consists of multiple aquifers and a depth to water table ranging from 50 to 110m. Within it, transmissivity values of 37.54 to 95.5m2 /day and a yield of up to 5litres/sec were recorded. The Ameki/Nanka Sands is a prolific water producer and underlies Aguata, Anaocha, Njikoka, Dunukofia, Oyi and Anambra East Local Government Areas. Four aquifer horizons were identified within this formation, designated; shallow, upper, middle and deep aquifers. The most exploited are the upper and middle aquifers, while the least, but most prolific is the deep aquifer with an average yield of 5litres/sec. Imo Shale, because of its sedimentological nature is a poor aquifer. The gravelly intercalations within this formation are usually too thin to sustain continuous water pumping. This study indicates that the extent and distribution of groundwater within the study area is controlled predominantly by lithology and other secondary factors including topography and nearness to source of recharge.
  • Item
    Open Access
    Geoelectrical Investigation of Groundwater Potential At Riol Farm, Owode, Abeokuta, Ogun State
    (Journal of the Nigerian Association of Mathematical Physics, 2016) Adeoti, Lukumon; Ijezie, N.T; Adegbola, R.B; Ojo, A.O; Afolabi, S.O; Adesanya, O.Y
    Geoelectrical investigation was carried out in order to solve the problem of drilling unproductive boreholes in RIOL Farm situated at Owode, Abeokuta in Ogun State. Fifteen (15) Schlumberger Vertical Electrical Sounding (VES) with current electrode spacing (AB) ranging from 2 m to 1000 m were acquired using PASI resistivity meter. The VES data were processed and interpreted using partial curve matching and computer iteration technique using WinRESIST software. The qualitative analysis reveals that the rising curves are dry sand devoid of groundwater while the descending parts of the VES curves are indicative of wet sands which could serve as potential aquifer. Four geoelectric sections generated from the interpreted VES results show four to six geo-electrical layers which correspond to topsoil with resistivity ranging between 45.0-993.9 ohm-m and thickness range between 0.5-1.0 m, lateritic clayey sand with resistivity ranging between 61.8-2328.0 ohm-m and thickness range between 1.2-5.5 m, sand/sandstone having resistivity range of between 1003.4-9575.9 ohm-m and thickness range between 4.2-114.8 m, sand with resistivity value ranging from 318.9-1581.2 ohm-m and thickness range between 5.1-78.9 m and consolidated sandstone / ironstone with resistivity value between 23245.5-4388.7 ohm-m. The quantitative analysis reveals that sands at the upper layer are dry within the depth of 2.2 – 69.8 m and appear to be unsaturated while sands at the depth not less than 80 m in VES 2, VES 9 and VES 15 are wet (saturated) and recommended for drilling. Thus, the wet sands denote aquifer units in the study area. Based on our recommendation, the location of VES 15 was drilled and yielded a productive borehole within a depth of 110m.