Study Reach.--The channel reach is constructed in an urban setting, as shown in the quadrangle map on the top left. The study reach, about 980 ft long, is located from the South William Street bridge to the South George Street bridge. Four surveyed cross sections (surveyed by the U.S. Corps of Engineers, May 2003) are available for describing the channel geometries in the study reach. The channel alignment, approximate variations in channel width and bank conditions, and locations of cross sections are shown in the aerial photograph on the top right. Cross-sectional plots at four river stations (RSs), as shown above, are selected to illustrate the variation in cross-sectional geometry.
Gage Location.-- The location where discharge measurements are made is lat 42°03’05”, long 87°55’30”. The study reach is located at SW1/4 SE1/4 SE1/4 sec.12, T.41N., R.11E., Cook County, Hydrologic Unit 07120004, on the right bank 10 ft upstream from the bridge on State Highway 58 (Golf Road) in Des Plaines, 2 mi west of US Highway 45 and at mile 3.6. The study reach is located upstream from the gagehouse. The USGS streamgage station number is 05529995.
Drainage Area.--12.81 sq mi.
Gage Datum and Elevations of Reference Points.--Datum of the gage is 634.02 ft. RP-2 is a bolt in the concrete guardrail on the downstream side of the Williams Street bridge located about midchannel, elevation = 656.492 ft. RP-1 is a bolt in the concrete guardrail on the upstream side of the George Street bridge located about midchannel, elevation = 654.325 ft. All elevations are referenced to NGVD29.
Stage, Discharge Measurements, and Computed n-Values.--Water surface elevations are measured by taping down from RP-1 on the upstream side of the George Street bridge and from RP-2 on the downstream side of Williams Street bridge. Discharge measurements are made from the downstream side of the Williams Street bridge or by wading in the vicinity of the downstream side of the bridge. When possible, multiple discharge measurements were made during a rise and recession to provide data for calculating n-values over a range in stage. The computed n-values are listed in the following table. Whenever possible, the computed n-values are associated with a photograph taken at the time of the measurement. The photographs are arranged from low to high discharge in order to illustrate the contributing factors of n-values at a particular discharge.
| Date of Observation | Discharge (ft3/s) | Average Cross Section Area (ft2) | Hydraulic Radius (ft) | Mean Velocity (ft/s) | Slope (ft/ft) | Coefficient of Roughness n |
|---|---|---|---|---|---|---|
| 5/2/2006 | 8.4 | 11.3 | 0.81 | 0.78 | 0.001450 | 0.092 |
| 4/25/2007 | 48.4 | 22.3 | 1.38 | 2.21 | 0.001330 | 0.044 |
| 4/25/2007 | 51.2 | 23.2 | 1.43 | 2.25 | 0.001340 | 0.044 |
| 6/26/2006 | 60.6 | 28.3 | 1.65 | 2.17 | 0.001330 | 0.050 |
Description of Channel.--This channel has been modified. The streambed material consists of coarse sand and gravel in 12 inch monoslab pavers. The bank consists of gabion boxes at the toe with predominantly short grass and weeds up the banks. The cross sections are fairly uniform and nearly trapezoidal. Light tree cover occurs just upstream of George Street bridge. The channel is straight.
Floods.--Maximum discharge during period of record, 1,590 ft3/s on June 10, 1967, gage height, 15.09 ft.
U.S. Department of the Interior |
U.S. Geological Survey
URL: http://il.water.usgs.gov/proj/nvalues/db/sites/05529995.shtml[an error occurred while processing this directive]?
Page Contact Information: David Soong
Page Last Modified: February 4, 2013
