Manning's roughness coefficients (n-values) presented in this Web are averaged reach-wise n-vlaues. These n-vlaues are computed with flow, water surface slope, and channel geometry collected from selected streams in Illinois. Only in-bank flows are considered at present. In order to provide information for estimating n-values at other hydraulic and/or geometric conditions, the site- and event-specific data are organized into data pages using a format similar to the Barnes report (1967), which is known as the visual approach for estimating n-values. Stream reaches that are selected characterize those representing natural or man-made cross sections, natural or artificial surface roughness, and in rural or urban settings. Efforts are made to include a range of n-values computed from hydraulic data collected at different stages at a site. Attempts also are made to enhance the presentation of the topographic features of a study reach; and to describe the geometric and hydraulic factors pertaining to the computed n-values in the site descriptions.
The USGS Illinois Water Science Center (USGS-ILLWSC) and the Illinois Department of Natural Resources-Office of Water Resources (IDNR-OWR) conducted this study. Using links provided at the left-hand-side of the Web, readers can view or download selected site pages. Readers can also link to reports of similar studies conducted at other Water Science Centers of the U.S. Geological Survey (USGS) or other agencies, to compute n-values using various methods that can be found in literatures, and to search for sites that have the range of n-values specified by the readers. Other search or computational functions will be provided when feasible. To view the study report, use the links provided at the end of this page.
The Web page being continuously revised so it can provide information to users in the most clear and useful form. Please forward any comments to David T. Soong or Teresa M. Halfar (USGS), or Loren Wobig (IDNR-OWR).
USGS:
David T. Soong: dsoong@usgs.gov,
phone: 217 328 9717, fax: 217 344 0082
Teresa M. Halfar: thalfar@usgs.gov,
phone: 217 328 9714, fax: 217 344 0082
IDNR - OWR
Loren A. Wobig: loren.wobig@illinois.gov,
phone: 217 782 9130, fax: 217 785 5014
This project is being conducted by the USGS-ILLWSC in cooperation with the IDNR-OWR. We want to give our thanks to many private land owners whom gave us permission to conduct field measurements from their properties. Data collections and surveying of channel cross sections have been conducted by the USGS-ILLWSC staff. Channel cross-sectional geometry and datum also have been obtained from IDNR-OWR, Illinois Department of Transportation, U.S. Army Corps of Engineers Chicago, Rock Island, and St. Louis Districts, and from municipalities and private consultant firms. Former USGS-ILLWSC student employee Megan A. Jupin and King Shan Kwok made tremedous contributions to the data analysis and maintenance of this Web page.
This web page is still under construction. Many web functions will be developed in the future. Provisional data are for review/comment only. Your comments and suggestions are invaluable to us for serving the information/results better.
Disclaimer
USGS data on this page have not received Director's approval and as
such are provisional and subject to revision. The data are released on
the condition that neither the USGS nor the United States Government
may be held liable for any damages resulting from their use.
Data from other agencies are displayed for informational purposes only.
The USGS is not involved with the collection, checking, and analysis of
other agency data. Questions and/or comments concerning other agency
data should be directed to the respective agency.
U.S. Department of the Interior |
U.S. Geological Survey
URL: http://il.water.usgs.gov/proj/nvalues/index.shtml
Page Contact Information: David Soong
Page Last Modified: Tuesday, 17-Mar-2009 21:43:18 CDT
