IDENTIFICATION OF THE PERMEABILITY DISTRIBUTION IN SOIL BY HYDRAULIC TOMOGRAPHY

A tomographical method is presented that allows the reconstruction of the structure of soil layers between two boreholes. If the soil is wat er saturated, the transient field equation for pore water pressure s(x )partial derivative(t)u(x, t)-del . (k(x)del u(x, t)) = Q can be used to reconstruct the soil structure from its permeability k(x). The tran sient potential field u(x, t) is controlled by hydraulic dipoles (poin t source and point sink). The positions of source and sink are varied over both boreholes. Pore water pressure observations are used as data for the inverse problem. Uniqueness problems are discussed. The forwa rd problem is discretized in a FE algorithm, the inverse problem solve d by a standard output least-squares method.