Hydraulic characterization of a contaminated aquifer is an important step in depollution processes because its hydraulic parameters control the choice and efficiency of the depollution protocol to be adopted. The characterization presented in this article uses a 3D electrical resistivity imagery to identify the spatial heterogeneities of a contaminated aquifer under tidal influence. Indeed, we use a 3D resistivity model as a source of information to parameterize the reconstruction of the hydraulic conductivity in 3D by inverting a set of hydraulic data acquired on the 13 monitored wells in response to two pumping tests. This parameterization relies on the identification of the main electro-facies in the resistivity model in the saturated zone, which will then be exploited in the hydraulic characterization to find their corresponding hydraulic conductivity values.This strategy of parameterization permits to reduce the number of the hydraulic conductivity parameters to be identified to eight hydro-facies, with a stochastic algorithm called the Adaptive Metropolis Algorithm. The hydraulic responses associated with the pumping tests are obtained once the natural effect of the tide is removed. The hydraulic conductivity model has permitted to highlight the main heterogeneities in the aquifer in which the hydraulic conductivity is ranging between [10-4.6, 10-2.8 m/s]. This range of variability reveals the permeable and smooth character of the aquifer in which the presence of coarse sand and flint blocks enhances its transmissivity. These permeable zones are electrically identified by resistive anomalies in the 3D electrical resistivity imaging.