Floods in Wisconsin: Magnitude and frequency

Abstract

Flood data from gaging stations on Wisconsin rivers and streams are listed in this report. From these data, composite frequency curves were defined which express the ratio of floods of various recurrence intervals to the mean annual flood. Multiple correlation techniques were used to obtain formulas that relate the basin parameters of drainage area, main channel slope, and lake and reservoir surface area to the mean annual flood. By combining the results from the mean annual flood formulas with the regional frequency curves, the flood-frequency relationship can be determined for most sites in the State where the drainage basin exceeds 20 square miles. The curves and formulas are not applicable to: main stem of several of the larger rivers, highly regulated streams where it is possible for man to alter flood peaks, and drainage basins under 70 square miles in a part of west-central Wisconsin. Irainage area ]sq mi)

Peak streamflow trends in Wisconsin and their relation to changes in climate, water years 1921–2020

“…USGS efforts to analyze peak-streamflow data in Wisconsin began in 1961 with the first flood-frequency estimates for streamgages estimated by hand-drawing the best visual fit for the flood-frequency relations and developing regression equations for ungaged areas (Ericson, 1961). After this first report, updates to Wisconsin flood-frequency estimates were published at roughly 10-year intervals using updated data and statistical techniques.…”

Patterns of variation in a fluvial system

“…The pattern, however, is somewhat modified by local geologic structure, especially joint systems, folds, and faults that have a tendency to control the orientation of. many valleys [Carlson, 1961 ] drainage area-discharge curve for gaged streams having similar climate and analogous physiographic settings to the study area was established from flow data taken from flood magnitude and frequency reports for Iowa [Schwob, 1964] and Wisconsin [Ericson, 1961]. All bank-full discharge values were generated from this equation for the ungaged streams in the Pecatonica watershed.…”

Estimating flood magnitude and frequency for unregulated streams in Wisconsin

“…Periodic updates of flood frequency estimates and regional regression equations are necessary to incorporate new data and methods. There is a lengthy history of flood frequency studies in Wisconsin starting with an initial report in 1961 (Ericson, 1961) and with additional reports following roughly every 10 years with updated data and statistical techniques (Conger, 1971;Conger, 1981;Krug and others,1992;Walker and Krug, 2003;Walker and others, 2017). Since the publication of the previous flood frequency report by Walker and others (2017), the USGS has issued new guidelines for estimating flood frequency estimates at gaged locations (England and others, 2019).…”