Assessment of injection well (IWs) as a measure of flood control

Abstract

The study examined the reliability of injection wells (IWs) as a control measure of flood and flood-related activities con sidering the relevance and the role of groundwater to human and industrial activities. Seventeen Boreholes (BHs) includ ing one as control, and three IWs in Government Reservation Area (GRA), Benin Metropolitan City (BMC) were used for the study. Groundwater flow and geospatial maps for the study area, and other parameters were generated and modelled using sufer15 2D modelling software in addition to correlation analysis. The parameters include pH, Turbidity, Lead (Pb), Nickel (Ni), Chromium (Cr), Iron (Fe), Coliform and E. coli Counts. The results showed that Pb in BHs BH8, BH9, BH3, BH4, BH5, BH12, BH15 BH16; Ni in BH5 and BH16; Cr in BH3 and BH15; Fe in BH4 and BH16 and the three IWs do not meet the required limit of 0.01, 0.02, 0.05 and 0.3 mg/L set by Nigeria Standard for Drinking Water (NSDWQ) and World Health Organization (WHO). All BHs and IWs were severely polluted with Coliform Count with the highest value of 22000 cfu/100 mL in IW1and lowest of 360 cfu/100 mL in control BH17 against 0 cfu/100 mL recommended in potable water by regulatory agencies. Correlation at P < 0.01 two-tailed together with geospatial maps indicates that IWs influences the quality of groundwater source in the area. Based on the finding in this study, IWs as control measures for flood and flooding-related activities can only be applied when the aquifer geometry is known otherwise, it should be discouraged.