Sensitivity and resolution of tomographic pumping tests in an alluvial aquifer

Various investigators have proposed hydraulic tomography, the simultaneous analysis of responses to multiple well tests, as a means to obtain a high‐resolution characterization of aquifer flow properties. This study assesses the information content of drawdown records from a set of tomographic pumping tests in an alluvial aquifer, comparing the parameter sensitivity and resolution associated with transient and steady‐shape formulations of the objective function for the parameter estimation problem. The steady‐shape approach takes advantage of the rapid establishment of constant gradients within the region surrounding a pumping well, comparing observed drawdown differences within this region with drawdown differences predicted by a steady state model. Both the transient and steady‐shape approaches resolve K variations only within a limited distance of the pumping intervals and observation points. Relative to the transient approach, the steady‐shape approach reduces the influence of poorly resolved property variations, including K variations outside the region of investigation and storage coefficient variations throughout the model domain.