Hydro-geological surveys and evaluation in parts of Anambra state, Nigeria

Abstract

Hydro geological surveys and evaluation were carried out in parts of Anambra State, Nigeria, A multi-objective, multi-technique; multidisciplinary and integrated approach was adopted in the area. The hydro-geological parameters (Water quality parameters tested fall within the WHO standard, desirable, permissible and acceptable limits, except for the high iron, nitrate contents of most surface waters and Nnewi ground-water for which appropriate treatments have been advised under discussion. The ground water, resources potentials are quite promising with high yield, high transmissivity, good specific capacity and minimal drawdown. Hydro geological environment depends on the aquifer of interest, and varies from formation to formation. The empirical hydro geological model shows that when the apparent resistivity for a 150m current electrode spread and below, comes to the average of 175, the ground water resources potential is promising. Imo shale formation, Nanka Sands formation, and  Ogwashi-Asaba formation reveal the total depth of boreholes are at average of 62m to 550m, 150m and 550m, and 120.5m to 178.0m respectively. The Imo Formation has poor permeability but good storage. The Nanka Sands formation shows that the study area with a thickness of 120m to 440m in several places used for the study. The hydro geochemical study in Imo shale shows the average ph of the aquifier ground water is between 4.8 to 6.5 pH scales, with maximum permissible pH scale of 8.5, Nanka sand areas show the average ph of the aquifier ground water is between 5.0 to 6.6 pH scales, with maximum permissible pH scale of 8.5, while Ogwashi-Asaba formation also shows the average ph of the aquifier ground water is between 4.9 to 6.5 pH scales, with maximum permissible pH scale of 6.5. The Ogwashi-Asaba hydro geological data indicate good yield aquifers and its formation has equally good yields aquifer. The hydro geochemical study acquired along with derived and computed analyses of results of pumping tests of boreholes appraised in this study in parts of the study area, indicate the study area is hydro-geologically promising.