Hydrodynamic Characterization of Fractured Aquifers in Precambrian Basement of Côte d’Ivoire: Geostatistical and Statistical Approaches

Abstract

This study concerns 10 communities of Côte d'Ivoire sampled in six regions. The study aims to provide better knowledge of hydrodynamic properties of fissured aquifers from Precambrian basement of Côte d'Ivoire. Geostatistical and statistical methods are used to analyze transmissivities and specific capacities. Transmissivity and specific capacity were determined after drawdowns corrections from pumping data and using traditional and numeric methods. Indeed, the pumping test carried out in isolate drilling and drawdowns are measured in the same drilling. The results showed that these two parameters are distributed at least on 3 orders of magnitude which revealed evidence the heterogeneity of studied areas. Specific capacity mainly is low and seldom exceeds 10 m2/h in water supply project of rural regions. The lowest values recorded in Bondoukou area with specific capacities values lower than 0.5m2/h. There is a large dispersion of data in many areas (Oume, San Pedro, Agnibilekro, Abengourou, etc.). Indeed, transmissivity and specific capacity data are scattered (Cv> 100%). These two parameters are distributed following lognormal law. In each area, an empirical relationship was established. This relationship can be used to assess the transmissivity in the areas where this parameter is difficult to determinate. Variograms of transmissivity in these areas are structured with significantly nugget effect. Variogram of San Pedro area is the most structured with a range equals to 60 km. The weakest one is obtained at Oume (with a range equal to 7 km). Assessment of the transmissivity by krigeage of 4 studied areas (Man-Danane, Bondoukou, San Pedro and Oume) is good and significant. However, estimated values of the transmissivity present a short order of magnitude compared to experimental values. The results achieved through this study contribute to better knowledge of fissured aquifers from Precambrian basement of Côte d'Ivoire.