Hydrogeologic Characteristics of Shallow Glacial Drift Aquifers in Dissected Till Plains (North-Central Missouri) |
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| Authors: | John M Sharp Jr |
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| Institution: | Associate Professor, Department of Geological Sciences, P.O. Box 7909, The University of Texas, Austin, Texas 78712. |
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| Abstract: | The dissected till plains physiographic province contains extensive areas of pre-Illinoian drift in Kansas, Nebraska, Iowa, and Missouri. The drift is typically a clay-rich, oxidized, and highly weathered till. In many areas of Missouri, this shallow drift represents the only readily available aquifer suitable for domestic and small agricultural users. There are, however, only few published data on the region's hydrogeology. Water budget analyses indicate that approximately 30% of mean annual rainfall is discharged by stream flow and 70% by evapotranspiration. The shallow drift flow systems are best considered unconfined, steady-state systems. Each watershed corresponds roughly to a local ground-water system. There is, typically, little hydraulic connection between the shallow drift systems and underlying strata. The drift hydraulic conductivity varies from approximately 1011 m/sec (laboratory tests) to 10−6 to 10−7 m/sec (field tests) when permeable sand lenses or joints are intersected. Ground-water discharge is concentrated in the immediate vicinity of stream channels, and recharge is concentrated on nearly horizontal hillslope summits. The ground water is generally potable (averaging 455 mg/1 total dissolved solids), but may be high in iron or polluted locally by organic wastes. |
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