Estimates of recharge to unconfined aquifers and leakage to confined aquifers in the seven-county metropolitan area of Minneapolis-St. Paul, Minnesota
Water-Resources Investigations Report 2002-4092
Prepared in cooperation with Anoka, Carver, Dakota, Hennepin, Ramsey, Scott, and Washington Counties and the Minnesota Board of Soil and Water Conservation
- James F. Ruhl, Roman Kanivetsky, and Boris Shmagin
Recharge to unconfined aquifers in the seven-county Twin Cities metropolitan area of Minnesota was estimated by five methods. Mean recharge estimated as a percentage (27 percent) of precipitation ranged from 7.7 to 8.3 in./yr across the study area. The median recharge estimated from automated analyses of streamflow-recession displacements for seven basins ranged from 1.2 to 12.2 in./yr. Median recharge estimated from graphical analyses of groundwater level fluctuations for 11 wells ranged from 4.5 to 13.6 in./yr. Recharge estimated by age dating of shallow ground water at a nested well site was 8.8 in./yr. Minimal ground-water recharge estimated by statistical analyses of watershed characteristics (geologic data and streamflow records) ranged from less than 0.1 to 5.6 in./yr.
Leakage, considered recharge to confined aquifers, in the seven-county Twin Cities metropolitan area was estimated by two methods. Leakage estimated by analyses of ground-water level fluctuations for 11 wells ranged from 3.2x10-3 to 1.1x10-2 in./yr. Leakage estimated by analyses of vertical-hydraulic gradients based on application of the Darcy flow equation for seven nested well sites ranged from 4.6x10-5 to 1.1x10-1 in./yr.
Recharge estimates, which generally varied within 10 in./yr for each of the methods, generally were largest based on the precipitation, ground-water level fluctuation, and age dating of shallow ground water methods, slightly smaller based on the streamflow-recession displacement method, and smallest based on the watershed characteristics method. Leakage, which was less than 1 in./yr, varied within 1 order of magnitude based on the ground-water level fluctuation method and as much as 4 orders of magnitude based on analyses of vertical-hydraulic gradients.
Additional publication details
- Publication type:
- Publication Subtype:
- USGS Numbered Series
- Estimates of recharge to unconfined aquifers and leakage to confined aquifers in the seven-county metropolitan area of Minneapolis-St. Paul, Minnesota
- Series title:
- Water-Resources Investigations Report
- Series number:
- Year Published:
- U.S. Geological Survey
- Publisher location:
- Mounds View, MN
- Contributing office(s):
- Minnesota Water Science Center
- iv, 32 p.
- United States
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