Data-collection methods and data summary for verification of a one-dimensional, unsteady-flow model of the Fox River in northeastern Illinois, October-November 1990

Abstract

Synoptic-study measurements of unsteady streamflow and dye concentrations were collected on a 49.4-mile reach of the Fox River in south-eastern Wisconsin and northeastern Illinois in October and November 1990. The study area included the Fox River and its major tributaries from Wilmot, Wis., downstream to South Elgin, Ill. The measurements were obtained to verify a one-dimensional, unsteady-flow model of the river system. Unsteady-flow conditions were created through operation of flow-control structures at Stratton Dam near McHenry, Ill. On November 1, 1990, dam gate openings were decreased to 0.1 foot. Openings remained at 0.1 foot until low flow was established throughout the reach. On November 5, the gate openings were increased to 2.5 feet. The change in gate openings created unsteady-flow conditions by allowing flow through the gates to increase from about 60-80 cubic feet per second to about 1,600 cubic feet per second. During the study period, discharge was computed continuously from stage records with stage-discharge relations at 7 stations on the Fox River and its tributaries; discharge was measured at 15 additional stations in the basin. Stage was recorded continuously at 15 stations in the basin (11 stations on the Fox River and 4 stations on the Fox River tributaries); stage was measured periodically at 8 additional stations on the Fox River. Fluorescent dye was injected continuously at Stratton Dam from November 2-8, 1990, during the unsteady flow to measure time- and space-integrated characteristics of the velocity flow field. Water samples were collected for fluorometric analysis at 18 sites downstream from the injection.