Estimating Flood Magnitude and Frequency for Unregulated Streams in Wisconsin

Scientific Investigations Report 2022-5118
Prepared in cooperation with Wisconsin Department of Transportation
By:  and 



Flood frequency characteristics and estimated flood discharges for the 50-, 20-, 10-, 4-, 2-, 1-, 0.5-, and 0.2-percent annual exceedance probabilities were computed at 299 streamgaged locations in Wisconsin. The State was divided into four flood frequency regions using a cluster analysis to produce regions which are homogeneous with respect to physical basin characteristics. Regression equations relating flood discharges to basin characteristics within each region were developed and can be used to estimate flood discharges at ungaged locations in Wisconsin. Basin characteristics included in the final regression equations include drainage area, saturated hydraulic conductivity, percent forest, percent herbaceous upland, percent open water, and the maximum 24-hour precipitation with a 10-year recurrence interval. The standard error of prediction for regression equations ranges between 40 and 71 percent, and the pseudo coefficient of determination ranges between 0.8 and 0.95. Nonmonotonic trends in the annual peak flow time series in the southwest part of the State are producing bias in some flood discharge estimates at streamgages with shorter (less than 20 years) periods of record. This bias increases the uncertainty in regression equations in this flood frequency region.

Suggested Citation

Levin, S.B., and Sanocki, C.A., 2023, Estimating flood magnitude and frequency for unregulated streams in Wisconsin: U.S. Geological Survey Scientific Investigations Report 2022–5118, 25 p., [Supersedes Scientific Investigations Report 2016–5140.]

ISSN: 2328-0328 (online)

Study Area

Table of Contents

  • Abstract
  • Introduction
  • Description of Data
  • Flood Frequency Analysis at Gaged Locations
  • Regional Flood Frequency Regression Equations
  • Application of Techniques for Estimating Flood Magnitudes at Gaged and Ungaged Locations
  • Summary
  • References Cited
Publication type Report
Publication Subtype USGS Numbered Series
Title Estimating flood magnitude and frequency for unregulated streams in Wisconsin
Series title Scientific Investigations Report
Series number 2022-5118
DOI 10.3133/sir20225118
Year Published 2023
Language English
Publisher U.S. Geological Survey
Publisher location Reston, Va.
Contributing office(s) Upper Midwest Water Science Center
Description Report: v, 25 p.; 2 Data Releases
Country United States
State Wisconsin
Online Only (Y/N) Y
Google Analytic Metrics Metrics page
Additional publication details