Numerical Identification of Parameters in Leaky Aquifers

A method using the nonlinear least‐squares and finite‐ difference Newton's method is presented to identify the parameters from pumping tests in homogeneous and isotropic leaky aquifers both for the situations with and without storage effects in the aquitard. Based on the least‐ squares approach, the sum of the squares of differences between the observed drawdowns and predicted drawdowns using the estimated parameters is minimized. The finite‐ difference Newton's method is used to solve the system of nonlinear least‐squares equations for the unknown aquifer parameters. Comparisons of the results among the proposed method, graphical method, and sensitivity analysis method when analyzing various data are presented. The proposed method has the merit of good accuracy and quick convergence from some initial guesses.