Publications

Alluvial groundwater adjacent to the main stem river is the principal nonpoint source of atrazine and deethylatrazine in the Cedar River of Iowa after the river has been in base flow conditions for 5 days. Between two sites along a 116-km reach of the Cedar River, tributaries contributed about 25% of the increase in the atrazine and deethylatrazine load, whereas groundwater from the...

The Basin Characteristics System (BCS) has been developed to quantify characteristics of a drainage basin. The first of four main BCS processing steps creates four geographic information system (GIS) digital maps representing the drainage divide, the drainage network, elevation contours, and the basin length. The drainage divide and basin length are manually digitized from 1:250,000...

No abstract available.

No abstract available.

Water samples were collected during the spring and summer of 1991 from 303 wells penetrating near-surface unconsolidated and bedrock aquifers of the midcontinental United States. Samples were analyzed for 11 herbicides, 2 dealkylated atrazine metabolites, and 4 nutrients. Specific conductance, pH, and dissolved-oxygen concentrations of the ground water were measured onsite. Ancillary...

No abstract available.

A hydrologic investigation to define the water quality of Corydon Reservoir before implementation of agricultural best-management practices in the basin was conducted from September 1990 to September 1991. Runoff from the 1,680-acre basin is the primary source of water to the 58-acre reservoir. Current water quality of the reservoir is affected substantially by runoff from the...

From mid-June through early August 1993, flooding was severe in the upper Mississippi River Basin following a wet-weather pattern that persisted over the area for at least 6 months before the flood. The magnitude and timing of several intense rainstorms in late June and July, combined with wet antecedent climatic conditions, were the principal causes of the flooding. Flood-peak...

Drainage-basin and channel-geometry multiple-regression equations are presented for estimating design-flood discharges having recurrence intervals of 2, 5, 10, 25, 50, and 100 years at stream sites on rural, unregulated streams in Iowa. Design-flood discharge estimates determined by Pearson Type-Ill analyses using data collected through the 1990 water year are reported for the 188...

National Water Summary 1990-91 Hydrologic Events and Stream Water Quality was planned to complement existing Federal-State water-quality reporting to the U.S. Congress that is required by the Clean Water Act of 1972. This act, formally known as the Federal Water Pollution Control Act Amendments of 1972 (Public Law 92-500), and its amendments in 1977,1979,1980,1981,1983, and 1987, is the...

On April 13, 1992, a section of a 100-year-old underground freight tunnel in downtown Chicago, Illinois was breached where the tunnel crosses under the Chicago River, about 15 meters below land surface. The breach allowed water from the Chicago River to flow into the freight tunnels and into buildings connected to the tunnels. As a result, utility services to more than 100 buildings in...

Contraction scour at the State Highway 2 bridge over the Weldon River in south-central Iowa was caused by a flood of record proportions on September 14 and 15, 1992. The peak discharge was 1, 930 cubic meters per second,which was 4 times the probable 100-year flood used to design the bridge, and resulted in road overflow. Contraction scour exposed the pier footings, but a subsurface...