Geophysical methods for locating groundwater in low permeability sedimentary rocks: examples from southeast Nigeria

MacDonald, Alan; Davies, J.; Peart, R.J.

doi:10.1016/s0899-5362(01)90022-3

Cited by 19 publications

(15 citation statements)

References 8 publications

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“…This aquifer is exploited mainly by hand-dug wells. Groundwater is found in open fractures at shallow depths of between 10 and 40 m. According to MacDonald et al (2001MacDonald et al ( , 2005a, the shales of the Asu River Group are characterized by high transmissivity which is related to the degree of burial and low-grade metamorphism of the shale host rock. The Agwu Shale which is not fractured has low transmissivity thus making it difficult to exploit the aquifer.…”

Section: Cenomanianmentioning

confidence: 99%

Hydrochemistry of surface water and groundwater in the shale bedrock, Cross River Basin and Niger Delta Region, Nigeria

et al. 2015

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Water chemistry in the shale bedrock of the Cretaceous-Tertiary of the Cross River and Niger Delta hydrological basins has been investigated using major ions. To carry out a characterization of the water bearing units, 30 and 16 representatives surface and groundwater samples were collected. The evolution of the water is characterized by enhanced content of sodium, calcium and sulphate as a result of leaching of shale rock. The spatial changes in groundwater quality of the area shows an anomalous concentrations of ions in the central parts, while lower values characterize the eastern part of the basin covering Ogoja, Ikom and Odukpani areas. The values of total dissolved solids (TDS) and ions increases down gradient in the direction of groundwater flow. The dissolution of halite and gypsum explains part of the contained Na ? , Ca 2? , Cl -and SO 4 2-, but other processes such as ion exchange, silicate weathering and pyrite oxidation also contribute to water composition. The assessment with contamination indicators such as TDS, hardness, chloride, nitrate and sulphate indicates that the water in area is suitable for human consumption in some locations. Modelling using MINTEQA2 program shows that the water from all the shale water bearing units are under saturated with respect to gypsum.

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Section: Cenomanianmentioning

confidence: 99%

Hydrochemistry of surface water and groundwater in the shale bedrock, Cross River Basin and Niger Delta Region, Nigeria

et al. 2015

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“…Oju/Obi is a remote part of SE Nigeria and experiences severe water shortages during the annual dry season, despite a high average annual rainfall of c. 1600 mm (Davies & MacDonald 1999). The area has been subject to extensive groundwater investigations in an attempt to improve the stubbornly high rates of guinea worm infection and low water supply coverage (MacDonald et al 2001(MacDonald et al , 2005(MacDonald et al , 2008Bonsor et al 2014). Oju/Obi is situated within the lower section of the Benue Trough, a major elongated geological rift structure infilled with fine-grained, low-permeability Cretaceous sediments (Ofoegbu 1985).…”

Section: Study Areamentioning

confidence: 99%

“…Smectite-dominated shale and the presence of dolerite intrusions were identified by combining frequency domain electromagnetic surveying and magnetic profiling, following a survey methodology developed by MacDonald et al (2001). Four 5-10 km surveys were undertaken in areas mapped to have mainly smectite-dominated shales.…”

Section: Geophysical Surveysmentioning

confidence: 99%

Fractures in shale: the significance of igneous intrusions for groundwater flow

MacDonald

Davies

2018

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Research in Cretaceous shales from West Africa has demonstrated that significant permeability can develop within shales at shallow depths (<100 m), equivalent to a permeability of >1 m day−1. Much of the variation in permeability is related to the degree of burial metamorphism, with shales that have been altered and that approach the anchizone having the highest permeability and those that are largely unaltered (early diagenetic zone) having the lowest permeability. However, further research targeting largely unaltered shales dominated by smectite clay has shown that the presence of small igneous intrusions can radically alter the hydrogeology. Twenty-four exploratory boreholes were drilled into smectite-dominated shale and nine of these boreholes were targeted to small dolerite intrusions within the shale. The dolerite was intensely fractured at the intrusion edge, with significant zeolite growth along the fracture surfaces. The permeability in the fractured dolerite was the highest measured in any shale borehole, with transmissivities of up to 60 m2 day−1 measured from pumping tests. Fracturing was less where dolerite was intruded into sandstones, however, and the measured transmissivity was lower (<0.5 m2 day−1). We postulate that the low permeability and high water content of the shale enabled high pressures to develop during intrusion, facilitating the development of fractures along the intrusion contact zone.

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“…, 1985;Bromley et al, 1996 ). Similarly, harder mudstones can also be distinguished from soft mudstone (MacDonald et al, 2001). In areas where large sandstone or limestone aquifers are present, little or no detailed siting is required for rural domestic supply; boreholes can be drilled anywhere.…”

Section: )mentioning

confidence: 99%

African hydrogeology and rural water supply

MacDonald¹,

Davies²,

Calow³

2008

IAH - Selected Papers on Hydrogeology

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The widespread development of groundwater is the only affordable and sustainable way of improving access to clean water and meeting the Millennium Development Goals for water supply by 2015. Current approaches to rural water supply, in particular demand driven approaches and decentralisation of service delivery have many benefits to the overall efficacy and sustainability of water supplies, however, problems arise when projects do not take into

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Geophysical methods for locating groundwater in low permeability sedimentary rocks: examples from southeast Nigeria

Cited by 19 publications

References 8 publications

Hydrochemistry of surface water and groundwater in the shale bedrock, Cross River Basin and Niger Delta Region, Nigeria

Hydrochemistry of surface water and groundwater in the shale bedrock, Cross River Basin and Niger Delta Region, Nigeria

Fractures in shale: the significance of igneous intrusions for groundwater flow

African hydrogeology and rural water supply

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