Characterization of the productivity of basement aquifers at Bagoué region (North of Côte d’Ivoire)

Abstract

This study aims to characterize the productivity of basement aquifers based on a database built by pumping test and drilling report from eighteen boreholes exploited in Bagoue region of Cote d’Ivoire. By using last version of a tool to assist in pumping test interpretation suggested by the French Mining and Geological Survey, Transmissivity parameter values of confined aquifers were determined through the well-known Theis method. In the same approach, critical yield value of borehole was determined at the equivalence point of linear and quadratic pressure drop from short-term pumping test data. Geostatistical analysis and kriging of transmissivity of aquifers were realized. Then, it was elaborated few predictive equations between hydrodynamic and hydraulic parameters based on their relationship level. Comparison of aquifers productivity and boreholes hydraulic capacity ended the methodology. Transmissivity ranged from 9.10-7 to 4.10-5 m2.h-1 while specific yield of boreholes reached between 0.34 and 23.07 m3.h-1. Yields from exploited boreholes varied between 0.5 m3.h-1 and 12 m3.h-1 with an average reaching 3.44 m3.h-1. Critical yield varied between 2.11 and 18.8 m3.h-1 with an average of 6.95 m3.h-1. According to geostatistical analysis of Transmissivity, its spatial spreading adjusted spherical model with a range reaching 0.13 meters. Findings highlighted 44 % of aquifer areas characterized by low value of transmissivity with great value of exploited outflow. That suggests a short-term availability of drinking water for living communities. In the same way, 11.11 % of boreholes were established into aquifer areas characterized by great transmissivity and low outflow values that suggests a better supply environment with long-term groundwater availability.