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Relation between stream-water quality and geohydrology during base-flow conditions, Roberts creek watershed, Clayton County, Iowa

Water Resources Bulletin

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DOI: 10.1111/j.1752-1688.1995.tb03387.x

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Abstract

An investigation to determine the relation between stream water quality and geohydrology in the Roberts Creek watershed, Clayton County, Iowa, was conducted during selected base-flow periods in 1988-90. Discharge measurements were made and water samples collected for analyses of nutrients and selected herbicides in 19 subbasins along the main stem and tributaries of Roberts Creek. The areal extent of unconsolidated and bedrock units subcropping in each subbasin was quantified. The hydrologic data were correlated statistically with the geologic data to determine relations. Roberts Creek generally gained water and had larger nitrogen concentrations in subbasins in which loess and alluvial material were underlain primarily by low-permeability till and shale units. Roberts Creek generally lost water and had lower nitrate concentrations in subbasins with subcropping karstic units. Nitrogen concentrations decreased in streams underlain by the karstic units because the nitrogen removed by biological processes was not replaced by ground-water inflow. Seepage from Roberts Creek to ground water in areas of subcropping karstic carbonate rocks reduced the flow, which reduced the velocity, causing increased residence time of water in the stream. The additional residence time may allow additional time for biological processes to remove nitrogen from solution. There was no significant relation between dissolved orthophosphate or atrazine and the underlying geology.

Additional Publication Details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
Relation between stream-water quality and geohydrology during base-flow conditions, Roberts creek watershed, Clayton County, Iowa
Series title:
Water Resources Bulletin
DOI:
10.1111/j.1752-1688.1995.tb03387.x
Volume
31
Issue:
4
Year Published:
1995
Language:
English
Publisher:
American Water Resources Association
Publisher location:
Bethesda, MD, United States
Larger Work Type:
Article
Larger Work Subtype:
Journal Article
Larger Work Title:
Water Resources Bulletin
First page:
593
Last page:
604