NUMERICAL-SIMULATION OF GROUNDWATER INTERACTION WITH LAKES ALLOWING FOR FLUCTUATING LAKE LEVELS

Most numerical models of ground-water flow incorporate lakes as consta nt head nodes. We developed a computer package for the widely used MOD FLOW code to simulate three-dimensional steady-state and transient gro und-water flow with fluctuating lake levels. This package considers pr ecipitation to and evaporation from the lake surface, stream flow, and ground-water inflow and outflow for multiple lakes. We demonstrate th e use of the package through the results of steady-state and transient simulations for a hypothetical ground-water flow problem involving a lake and two streams.