A groundwater flow model of Indian Wells Valley, California, Utilizing GMS with GIS applications

Abstract

The sustainability of a potable groundwater supply in the regional aquifer of Indian Wells Valley, California, is threatened by overdraft and by induction of contaminated upper aquifer waters into the lower, regional aquifer. A three layer MODFLOW groundwater model is developed in GMS (Groundwater Modeling System) to enhance understanding of the hydro logic flow regime and to serve as a groundwater management tool. The steady-state model is calibrated with water level measurements collected during 1920 and 1921. Water level data spanning several decades are used in transient model calibration. Calibration is by trial and error adjustment of the transmissivity with subsequent recharge refinement. Model simulated heads agree with observed heads in most regions within ten feet, except for the southwest, which may require additional field investigation. The model suggests that less than 5000 acre feet/year of recharge may supply the valley, compared with previous model estimates of 9840 acre-feet/year.