Thomas C. Winter 1976 <p>Because the interrelationship of lakes and ground water is perhaps the least understood aspect of lake hydrology, vertical-section, steadystate, numerical-model simulations were run to evaluate the factors that control the interaction of lakes and ground water. The study is concerned only with lakes encircled by water-table mounds that are at a higher altitude than lake level. Simulations of one-lake and multiple-lake systems in vertical sections show that for many hydrogeologic settings, the line (divide) separating local from regional ground-water flow systems is continuous beneath individual lakes. If the divide is continuous, there exists a point along it at which the head is a minimum compared to all other points along the divide. This point of minimum head is always greater than the head represented by lake level, therefore in such a setting there can be no movement of lake water through the lake bed to the ground-water system. In a setting where the divide is not continuous, the lake loses water through part of its bed, but rarely in the littoral zone of the lake.</p><p>Factors that strongly influence the position, shape, and continuity of the flow-system divide beneath lakes are height of the water table on the downslope side of the lake relative to lake level, position and hydraulic conductivity of aquifers within the ground-water reservoir, ratio of horizontal to vertical hydraulic conductivity of the groundwater system, and lake depth.</p> application/pdf 10.3133/pp1001 en U.S. Government Printing Office Numerical simulation analysis of the interaction of lakes and ground water reports