Building Piezometric Maps: Contribution of Geostatistical Tools

This paper shows practical applications of two kriging techniques: kriging with boundary conditions and kriging with external drift, which are used in order to introduce hydrogeological constraints when producing piezometric maps. These techniques are not new to geostatisticians, but not very well known by many hydrogeologists. Kriging with boundary conditions is implemented here with a discrete formulation that allows the use of non-differentiable or of anisotropic covariance models. Kriging with external drift is applied here in the case of an unconfined aquifer, the external drift being a smoothed version of the topography. A method is proposed to select the appropriate smoothing radius. Results show a clear improvement compared to standard kriging.