A SOLUTION TO THE INVERSE PROBLEM IN GROUNDWATER HYDROLOGY BASED ON KALMAN FILTERING

The paper introduces a new method for the solution of the inverse prob lem, that is, the estimation of parameters characterizing the hydrodyn amic behaviour of aquifers given their geometrical description, the pi ezometric field, the net infiltration (infiltration minus abstractions ) and the boundary conditions. The method, which falls in the class of Bayesian estimators, is based upon a Kalman filtering formulation whi ch optimally combines a priori parameter values with the information c ontained in the observations to obtain the a posteriori parameter esti mates. In that respect it can also be viewed as an extension of the su bjective weighting method proposed by Neuman and Yakowitz (Water Resou r. Res., 15(4), 1979). An example of the application of the proposed m ethod to two Libyan aquifers is presented, showing the statistical ade quacy of the resulting permeability estimates when compared with the p ermeabilities obtained at a number of points by means of pump tests.