TECHNIQUE FOR ESTIMATING MAGNITUDE AND FREQUENCY OF FLOODS IN ILLINOIS

A technique is presented for estimating flood magnitudes at recurrence intervals ranging from 2 to 500 years, for unregulated rural streams in Illinois, with drainage areas ranging from 0.02 to 10,000 square miles (0.05 to 25,900 square kilometers). Multiple regression analyses, using streamflow data from 241 sampling sites, were used to define the flood-frequency relationships. The independent variables drainage area, slope, rainfall intensity, and an areal factor are used in the estimating equations to determine flood peaks. Examples are given to demonstrate a step-by-step procedure in computing a 100-year flood for a site on an ungaged stream and a site on a gaged stream in Illinois.

  • Supplemental Notes:
    • Prepared in cooperation with Illinois State Div. of Highways, Springfield.
  • Corporate Authors:

    U.S. Geological Survey

    F Street Between 18th and 19th Street, NW
    Washington, DC    20244

    Illinois Department of Transportation

    Division of Highways, 2300 South Dirksen Parkway
    Springfield, IL  USA  62764
  • Authors:
    • Curtis, G W
  • Publication Date: 1977-7

Media Info

  • Pagination: 78 p.

Subject/Index Terms

Filing Info

  • Accession Number: 00175688
  • Record Type: Publication
  • Source Agency: National Technical Information Service
  • Report/Paper Numbers: USGS/WRD/WRI-78/009 Final Rpt., USGS/WRI-77-117
  • Files: TRIS
  • Created Date: Jun 28 1978 12:00AM