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Magnitude and frequency of Iowa floods, part one

Iowa Highway Research Board Bulletin 28
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Abstract

Iowa stream-gaging station records at 147 regular gaging stations and partial-record sites were analyzed to produce flood magnitude and frequency relations. An index flood which is the mean annual flood and two composite frequency curves are used to predict the flood-frequency curve for interior streams of the State.

The index flood was determined by a multiple correlation. The independent variables found to be significant are size of drainage basin, stream slope, and the normal annual precipitation for the 1931–60 period. The regression equations for two areas were determined—a large central area and a combination of areas in the northeastern and southwestern parts of the State.

All three independent variables were used in the central area. Only area and slope were found necessary in the remainder of the State. The ratio to the index flood at selected recurrence intervals was determined from each of the gaging-station flood-frequency curves.

The median of the ratios for the long term period (1916–65) is used to define the two composite curves. Maximum flood discharges at gaging stations and miscellaneous sites are tabulated and related to their frequency of occurrence. Together with the analysis previously described they form part one of a two part report. Basic data in the form of flood peak stages and discharges for each year of record at each gaging station are published in part two of the report.

Suggested Citation

Schwob, H.H., 1966, Magnitude and frequency of Iowa floods, part one: Iowa Highway Research Board Bulletin 28, 17 p.

Study Area

Publication type Report
Publication Subtype State or Local Government Series
Title Magnitude and frequency of Iowa floods, part one
Series title Iowa Highway Research Board Bulletin
Series number 28
Year Published 1966
Language English
Publisher Iowa Highway Research Board
Contributing office(s) Iowa Water Science Center
Description 17 p.
Country United States
State Iowa
Online Only (Y/N) N
Additional Online Files (Y/N) N
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