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Increased baseflow in Iowa over the second half of the 20th Century

Journal of the American Water Resources Association

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Abstract

Historical trends in annual discharge characteristics were evaluated for 11 gauging stations located throughout Iowa. Discharge records from nine eight-digit hydrologic unit code (HUC-8) watersheds were examined for the period 1940 to 2000, whereas data for two larger river systems (Cedar and Des Moines Rivers) were examined for a longer period of record (1903 to 2000). In nearly all watersheds evaluated, annual baseflow, annual minimum flow, and the annual baseflow percentage significantly increased over time. Some rivers also exhibited increasing trends in total annual discharge, whereas only the Maquoketa River had significantly decreased annual maximum flows. Regression of stream discharge versus precipitation indicated that more precipitation is being routed into streams as baseflow than as stormflow in the second half of the 20th Century. Reasons for the observed streamflow trends are hypothesized to include improved conservation practices, greater artificial drainage, increasing row crop production, and channel incision. Each of these reasons is consistent with the observed trends, and all are likely responsible to some degree in most watersheds.

Additional Publication Details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
Increased baseflow in Iowa over the second half of the 20th Century
Series title:
Journal of the American Water Resources Association
Volume
39
Issue:
4
Year Published:
2003
Language:
English
Larger Work Type:
Article
Larger Work Subtype:
Journal Article
Larger Work Title:
Journal of the American Water Resources Association
First page:
851
Last page:
860
Number of Pages:
10