HYDROGEOLOGY OF DUTSEN WAI SHEET125NW, NORTH WESTERN NIGERIA
HYDROGEOLOGY OF DUTSEN WAI SHEET125NW, NORTH WESTERN NIGERIA
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Date
2015-10
Authors
GANA, Victor
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Abstract
Hydrogeological investigation of topographical sheet 125DutsenWai NW was undertaken. This study area is located on the Crystalline Hydrogeological Province of northern Nigeria covering an area of about 742 km2. The area is underlain by undifferentiated gneisses, schists, fine to medium grained granites of Precambrian age, and medium grained Jurassic Younger Granites at DutsenWai Hill.Methodsfor this investigation include; field observation, sampling and laboratory analysis of rocks, measurements of water level in sixty (60) hand-dug wells, sampling of water for laboratory analyses from twenty (20) selected hand-dug wells, and locating boreholes with a satellite navigator. Twenty eight (28) borehole logs, drilled by Parkman/Water Survey and Preussag water supply companies were analyzed. Hydrogeological maps and cross-sections were constructed and aquifer properties were determined from pumping tests done by Parkman/Water Surveys and Preussag for the soft overburden aquifer and the fractured aquifer.Two interconnected water table aquifers were identified and mapped; the soft overburden aquifer with thickness varying between 18 to 56 meters and fractured crystalline aquifer below of average thickness of between 11 to 30 meters. Borehole yields range from 24.48 m3/day to 146.88 m3/day. Specific capacity, calculated from yield and drawdown, ranges from 1.35 m3/day to 36.69 m3/day, while the hydraulic conductivity values vary from 0.023 m/day to 0.629 m/day with average of 0.12 m/day. The calculated transmissivity values computed from Jacob and Babushkin approximate methods range from 0.615 m2/day to 15.057 m2/day and 0.70 m2/day to 19.70 m2/day respectively. These transmissivity values fall between 0.1 to 10 m2/day where the groundwater supply potential of the area is in the range of very low to low transmissivity magnitude. And as such, local and smaller withdrawals can effectively serve the rural populace in the study area since the area is sparsely populated and the distribution is uneven. Yields of the boreholes showed, that none of the boreholes in the study area has yield below the sustainable yield range of around 0.14 l/s (0.5 m3/h) for a hand-pump equipped well and 1.4 l/s (5 m3/h) for submersible pump equipped boreholes. As such, they can be installed with either hand pumps or submersible pumps successfully.The results of the chemical analysis of 20 water samples showed that Ca2+ ranges between 0.47 - 16.34 mg/l, Na2+ 6.00 – 43 mg/l, K+ 1.70 – 25.0 mg/l, Mg2+ 4.32 – 7.63 mg/l, Fe2+ 0.21 – 6.96 mg/l, S04- 0.00 – 6.76 mg/l, N03- 7.00 – 35 mg/l, HCO3- 90 – 420 mg/l, Cl- 0.25 – 2.50 mg/l and TDS concentration between 28- 385 mg/l falls far below the upper limit of the freshwater classification. The Piper’s trilinear diagram shows that the groundwater in the study area is of Na(K) HCO3 and Ca(Mg) HCO3 water types, while Schoeller’s semi – logarithmic plots also show the dominance of sodium and Bicarbonate ionic concentration. The Wilcox plot indicates that the measured electrical conductivity values fall within the sodium (alkali) hazard S1 which is low and salinity hazard C1 and C2 between low and medium thus confirming the acceptability of the water for domestic, agricultural and industrial uses. In summary; Water in the study area is of meteoric origin but it is polluted by residential pollution. It is possible that this pollution is limited to the rural settlements while the arable lands between the settlements arenon- polluted or polluted by agricultural activities
Description
A DISSERTATIONSUBMITTED TO POSTGRADUATE SCHOOL, AHMADU BELLO UNIVERSITY SAMARU, ZARIAIN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE AWARD OF MASTERS OF SCIENCE DEGREE IN GEOLOGY (HYDROGEOLOGY)
DEPARTMENT OF GEOLOGY
FACULTY OF SCIENCE
AHMADU BELLO UNIVERSITY SAMARU ZARIA
NIGERIA
Keywords
HYDROGEOLOGY,, DUTSEN WAI SHEET125NW,, NORTH WESTERN NIGERIA,