National Water Quality Assessment Program: Eastern Iowa Basins

Relation Between Stream Water-quality And Selected Basin Characteristics In Eastern Iowa

by K. K. Akers

Program abstract of the 110th Session of the Iowa Academy of Science meeting, April 25, 1998, Mason City, Iowa

As part of the National Water-Quality Assessment Program (NAWQA), water-quality studies began in October 1993 in the Eastern Iowa Basins. The Eastern Iowa (EIWA) study unit is in a primarily agricultural setting covering approximately 19,500 mi2 in eastern Iowa and southern Minnesota and includes the Wapsipinicon, the Cedar, the Iowa and the Skunk River Basins. One of the objectives of the NAWQA program is to determine the occurrence and distribution of major chemical elements in surface water. Surface-water samples have been collected monthly and during high-flow events since March 1996 at 12 sites within the EIWA study-unit. Within a drainage-basin many related factors such as geology, physiography, soils, land-use, and climate, contribute to surface-water runoff and affect the overall surface-water chemistry. Basinsoft, a computer program utilizing digital cartographic data was used to quantify the morphometric characteristics: total drainage area, basin length, average basin slope, basin relief, effective basin width, relative relief and main channel length. These drainage-basin characteristics and others generated were used to understand the effects of drainage-basin characteristics on the occurrence and distribution of major chemical elements within the Eastern Iowa Basins.

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