Modifications of a three-dimensional ground-water flow model to account for variable water density and effects of multiaquifer wells

Abstract

A three-dimensional finite-difference groundwater flow model was modified and used in the U.S. Geological Survey's Northern Midwest Regional Aquifer System Analysis to simulate the effects of wells open to various combinations of aquifers and the effects of groundwater density that varies spatially but is time invariant. The computer code for the slice-successive-over-relaxati^on solution method used to solve for head and a description of how it functions is given, as well as modifications that were made to account for the hydraulic effects of multiaquifer-wells. In addition, two programs are presented that compute data required for the simulation of variable-density effects: one program calculates model-block conductances and variable-density terms external to the groundwater flow model; the other computes groundwater and pure-water density and viscosity for input to the first program.