Abstract
An evaluation of the aquifer properties of the inland sedimentary Bida basin, central Nigeria, was conducted using empirical methods derived from particle size distribution curves. The main aquifer properties determined were hydraulic conductivity, porosity, effective porosity and coefficient of uniformity. Samples for analysis were obtained from test water wells drilled to 100m in selected parts of the Basin. The empirical method used was the Hazens method, while porosity was determined in the laboratory. The results show that three levels of aquifers generally exist in the Basin. The aquifer material consist of well sorted medium sand to fine gravel. The upper aquifer occurs at a depth of between 10 – 18m and has a hydraulic conductivity of 18.5m/d and effective porosity of 9.0. The second, or middle, aquifer occurs at a depth of between 45 – 65m and has a hydraulic conductivity of 37m/d and effective porosity of 20. The third, or lower, aquifer occurs between 80 – 100m and has a hydraulic conductivity of 32m/d and effective porosity of 24. Effective porosity generally increases with depth in the basin indicating coarsening up of the sandstone with fewer fine grained cementing material. Mean hydraulic conductivity value is 29.16m/d, porosity 63%, effective porosity of 6.7 and coefficient of uniformity of 2.8. The results have therefore shown that it is possible to obtain quantitative results from particle size distribution curves that are useful for the determination of hydraulic properties of aquifers.
Highlights
An aquifer is defined as a geological material that is capable of storing and transmitting water to wells placed in them in sufficient quantities to be considered economical
The results have shown that it is possible to obtain quantitative results from particle size distribution curves that are useful for the determination of hydraulic properties of aquifers
The first 8m of the Basin consist of sediments that are gap graded, which means a particular grain size is missing, and becomes well graded till 20m, uniformly graded at 32m and repeated the cycle again, this reflects the cyclic nature of deposition in the Basin indicating different periods of deposition which may characterize a continental environment of deposition when water level will rise at a particular period and has a high energy flux, drop at other periods with low energy flux
Summary
An aquifer is defined as a geological material that is capable of storing and transmitting water to wells placed in them in sufficient quantities to be considered economical. In hard rock areas the term can be used loosely for fractured and weathered rock The properties these materials must possess to be considered as aquifers include but not restricted to porosity, permeability, hydraulic conductivity and specific yield. These properties may vary spatially because of geologic heterogeneity. Laboratory tests are limited by non-availability of equipment in this part of the world, obtaining representative samples and long time required for testing Estimating these properties from empirical formulae based on grain-size distribution characteristics have been developed and used to overcome these problems (Uma et al, 1989). The specific objectives include a determination of the porosity, effective porosity, hydraulic conductivity and uniformity coefficient of the aquifer material at various depths in the basin
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
