Development of a Digital Groundwater Model with Application to Aquifers in Idaho

Investigations of water resources systems involving groundwater simulation are generally data-scarce projects. Insufficient geohydrologic data severely inhibits simulation of historic water table behavior. A finite difference model is expanded to include iterative procedures to adjust the initial estimates of geohydrological parameters (transmissibility, leakance factor, head difference in leaky aquifer system and storage coefficient) to match historic aquifer behavior. The model includes a mass balance calculation routine, a routine to simulate open surface drains and aroutine to calculate flow across hydraulically connected boundaries, such as a lake or stream. The parameter calibration routine as well as all other routines were tested and successfully applied to the gravel aquifer of the Snake River fan in eastern Idaho and the basalt aquifer of the Snake River plain in southern Idaho. The operational model successfully simulated the historic water table behavior in the aquifers and provides a reliable tool for studying effects of water management changes on aquifer behavior for research, planning or administrative purposes. The dissertation contains 52 reference