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Unsaturated-zone wedge beneath a large, natural lake

Water Resources Research

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DOI: 10.1029/2000WR900213

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Abstract

Lake Belle Taine (480 ha) in north central Minnesota receives on average 76,000 m3 d-1 of water from Little Sand Creek but has no outlet. Water seeps out of the lake, flows through glacial outwash, and discharges into three nearby lakes with stages 13-14 m lower than Belle Taine. Seepage-meter data indicate water is seeping out of Belle Taine at velocities up to 263 cm d-1. Hydraulic-head measurements made in the lake bed indicate the sediments are unsaturated beneath a portion of the lake edge, and a wedge of unsaturated sediments extends beneath the lake bed as much as 20 m from the shoreline. At the shoreline the water table is as much as 6.7 m below the lake surface. Modeling results of a similar hypothetical setting indicate that the horizontal extent of an unsaturated zone beneath a lake depends on (1) the permeability contrast between the outwash and the lake bed, (2) anisotropy, (3) lake bed slope, and (4) thickness of the lower-permeability lake bed sediments. Although rarely documented, unsaturated sediments beneath a lake may not be extremely uncommon. Similar, much smaller unsaturated-zone areas also have been observed beneath two other lakes in Minnesota.

Additional Publication Details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
Unsaturated-zone wedge beneath a large, natural lake
Series title:
Water Resources Research
DOI:
10.1029/2000WR900213
Volume
36
Issue:
12
Year Published:
2000
Language:
English
Larger Work Type:
Article
Larger Work Subtype:
Journal Article
Larger Work Title:
Water Resources Research
First page:
3401
Last page:
3409
Number of Pages:
9