Floods in Texas Magnitude and Frequency of Peak Flows

Patterson, James L.
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U.S. Geological Survey

This report outlines methods by which the magnitude and frequency of expected floods for most streams in Texas may be predicted. Peak discharge data from gaging stations have been used to define flood-frequency curves applicable to the State. Composite frequency curves were drawn showing the relation of mean annual floods to floods having recurrence intervals from 1.2 to 50 years. Other curves express the relation of the mean annual flood to contributing drainage area. By combining data from the two types of curves, flood-frequency curves may be drawn for streams in Texas not materially affected by regulation or diversion. The curves should not be extrapolated beyond the range defined by base data. In general, very large stream in the State do not lend themselves to regional analysis; therefore, they are given special treatment in this report. A tabulation of peak gage heights and discharges for most gaging stations in the State having as many as 5 years of record are included. In general, the tabulations include all peaks above a selected base discharge. For some stations only annual peaks are shown.