Estimates of annual ground-water contribution to streamflow
in 38 drainage basins of Minnesota by use of standard
streamflow hydrograph separation methods permit determination
of relations between ground-water runoff and such basin
characteristics as geologic environment, precipitation and
temperature, and percentage of lake and wetland cover.
Generalized conclusions derived from analysis of the data
are that ground-water runoff is (1) least from glaciated basins
that have surficial lake bed sediments or gray-drift ground moraine
immediately underlain by relatively impermeable bedrock
and (2) greatest from glaciated basins that have surficial depos
its immediately underlain by permeable bedrock or that have
thick surficial loess deposits immediately underlain by permeable
bedrock. Ground-water runoff is much greater from glaciated
basins having red drift than from basins having gray
drift. The rate of ground-water increases as annual precipitation
increases. Lakes and wetlands sustain and regulate
streamflow during rainless periods; if they were absent sustained
streamflow from northern parts of the state would be
Recharge to aquifers in the state is difficult to ascertain.
Because many aquifers are deeply buried by glacial materials
of varying characteristics, not all ground-water runoff can be
diverted into cones of depression, for there is some lateral
as well as vertical movement of water in surficial deposits.
Data on ground-water runoff can be useful in estimating the
rate of recharge to aquifers and in evaluating the potential
yields of ground-water reservoirs. However, no simple re-
1ation exists between ground-water runoff and ground-water
recharge or the potential yields of aquifers.
Studies of basin characteristics were handicapped because
of a lack of detailed geologic information. Collection and study
of data intended to describe the dimensions and water -yielding
properties of unconsolidated deposits in the basins of the state
are urgently needed to support hydrologic studies involving
ground-water development and management decisions.
Ackroyd, Earl A.; Walton, William C.; Hills, David L..
RI-06 Ground-Water Contribution to Streamflow and Its Relation to Basin Characteristics in Minnesota.
Minnesota Geological Survey.
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