Using specific capacity for assessing of the factors controlling borehole productivity in crystalline bedrock aquifers of N’Zi, Iffou and Moronou regions in the eastern area of côte d’Ivoire

Abstract

Hard rock aquifers are characterized by high heterogeneity which leads to difficulties in boreholes implementation in the eastern region of Côte d’Ivoire. This is due to the combination of many factors including poor knowledge of hydrogeological environment. The thrust of this study is to highlight the influence of borehole depth, lithotypes, weathering thickness and electrical resistivity of the geological structures on borehole productivity that exploit the crystalline aquifer systems in N’Zi, Iffou and Moronou regions. Bivariate analysis was used to determine the relationships between these factors and specific capacity values for measuring borehole productivity. The values ranged from 0.02 to 4.09 m3 h−1.m−1. The analysis shows that there is no correlation between productivity and weathering thickness. However, weathering depths between 10 and 69 m provide the highest specific capacity values. Schist is more productive than granite. For hydrogeological discontinuities interest, boreholes located in H and KH anomaly curve types were the most productive. As productivity diminishes with depth, a deeper borehole can be more productive if it reaches a geological structure that is favorable for groundwater flow. Those geological and hydrogeological parameters are extremely important in borehole productivity in the above-mentioned regions.