Hydro-geophysical study of michika and environs, northeast Nigeria

Abstract

Thirty-five Schlumberger vertical electrical soundings (VES) of maximum electrode spread of AB/2 100 m were carried out in Michika and its environs to study the distribution of groundwater and the aquifer systems. Two distinctive curve types; H and KA were identified. The H- type curves account for 97.14% while the remaining 2.86 are KA curve type. The lithologic sequences to be penetrated during drilling of boreholes in the area were deduced from the analysis and interpretation of the resistivity data. Three main geo-electrostratigraphic layers were obtained from the analysis of the resistivity data, with average thicknesses of 2.28 m for the first layer; 22.56 m for the second layer. The mean resistivity values obtained are 551 ohm-m, 109 ohm-m, and 3131.78 ohm-m; and these represent top soil/laterite, weathered/fractured granite and fresh basement, respectively. Based on the resistivity data analysis and interpretation the possible locations were delineated for productive boreholes of depths between 2.58-53.62 m were drilled. The water quality analysis revealed the predominance of moderately acidic water with pH value of 4.7 to slightly alkali water with pH value of 7.9 indicating water that is soft and slightly hard with low concentration of dissolved chemical constituents. The results also indicate that the water is tasteless and is suitable for domestic purposes and well as industrial and agricultural except for few cases where high concentration of nitrates (NO2, NO3), iron (Fe) and magnesium were obtained. Key words: Michika and its environs, geology, resistivity data interpretation and hydrogeology.