Water movement in till of east-central South Dakota
Factors that control the flow of water through till are poorly understood. Hydrographic analyses, field hydraulic conductivity measurements, and major-ion sampling were conducted on weathered and unweathered tills at 22 sites in east-central South Dakota. Water from a buried outwash aquifer was also chemically analyzed and carbon age dated. The upper part of most till has been weathered and exhibits extensive secondary permeability. Hydraulic conductivity values range from 10/sup -7/ to 10/sup -4/ cm/sec; typically 10 to 200 times higher than the hydraulic conductivity of unweathered till. Hydraulic gradients within weathered tills average seven times lower than within unweathered till. Water infiltrating below plant roots is believed to principally recharge and discharge the weathered till. Total dissolved solids were significantly higher in the weathered till than in the unweathered till. Water extracted from unweathered till is, in turn, up to three time higher in major-ion concentrations than water from the underlying outwash aquifer. Carbon-14 age dates from outwash aquifer water exceed 9000 years before present. Results indicate that Tittle to no water passes from the weathered till through the unweathered till into the buried outwash aquifer. Discharge from the weathered till is hypothesized to be primarily local lateral flow to sloughs, streams and ponds, combined with evapotranspiration losses during periods of high water table.
- Research Organization:
- Illinois State Water Survey, Champaign (USA)
- OSTI ID:
- 6646331
- Report Number(s):
- CONF-8510489-
- Journal Information:
- Geol. Soc. Am., Abstr. Programs; (United States), Vol. 17; Conference: 98. annual meeting of the Geological Society of America, Orlando, FL, USA, 28 Oct 1985
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
GROUND WATER
GEOCHEMISTRY
WATER CHEMISTRY
MORAINES
HYDROLOGY
SOUTH DAKOTA
AQUIFERS
CHEMICAL COMPOSITION
HYDRAULIC CONDUCTIVITY
ISOTOPE DATING
PERMEABILITY
SOLUTES
AGE ESTIMATION
CHEMISTRY
FEDERAL REGION VIII
GEOLOGIC DEPOSITS
HYDROGEN COMPOUNDS
NORTH AMERICA
OXYGEN COMPOUNDS
USA
WATER
580100* - Geology & Hydrology- (-1989)
580400 - Geochemistry- (-1989)