One‐dimensional simulation of aquifer system compaction near Pixley, California: 1. Constant parameters

Aggregate one‐dimensional compaction (consolidation) of a series of aquitards in a compacting aquifer system has been simulated through use of a finite difference representation of the vertical stress distribution within an idealized aquitard. Among the parameters affecting the simulated compaction are two storage coefficients (compressibility values), one for recoverable and the other for nonrecoverable compression. These two storage coefficients introduce a transient heterogeneity within an aquitard that is generally ignored by hydrologists. A computer program with two sets of constant coefficients calculates the daily deformation due to observed changes in applied stress near Pixley, California. Although water levels fluctuate annually, no long‐term water level decline occurred near Pixley between January 1, 1959, and February 4, 1971. During this period, 3.19 ft (0.972 m) of compaction was observed. The net difference between simulated and observed compaction on February 4, 1971, was 1.3% of the observed value. Maximum deviation occurred in mid‐1964 and equaled 7% of the observed compaction.