Regional Ground-Water Flow and Geochemistry in the Midwestern Basins and Arches Aquifer System in Parts of Indiana, Ohio, Michigan, and Illinois. Regional Aquifer-System Analysis - Midwestern Basins and Arches

摘要

This report presents information on the geohydrology ofand regional flow and geochemistry in the Midwestern Basinsand Arches aquifer system in parts of Indiana, Ohio, Michigan, and Illinois. Specific report objectives are to describe (1)physical and hydraulic boundaries of the aquifer system; (2) regional relations between surface water and ground water; (3) a numerical model used to compute a regional ground-water budget, regional recharge and discharge areas, and patterns of regional ground-water flow; and (4) ground-water chemistry in relation to these patterns of regional flow. In the Summary and Conclusions section of the report, the hydrological and geochemical information are integrated to presenta comprehensive analysis of the occurrence and flow of waterin the aquifer system. Regional flow, as defined for this report, is ground-waterflow associated with flow systems that are minimally affectedby seasonal variations in ground-water recharge from precipitation. Although local-scale flow systems that readily respond to variations in ground-water recharge are numerous and important throughout the aquifer system, it was outside the scope of the RASA project to investigate such flow systems. Specifically, local flow systems are not explicitly simulated by the numerical ground-water flow model.