7050

• UCREFRP Catalog Number: 7050
• Author: Andrews, E. D.
• Title: Effective And Bankfull Discharges of Streams In THe Yampa River Basin, Colorado and Wyoming
• USFW Year: 1980
• USFW - Doc Type: Journal of Hydrology
• Copyright Material: YES

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RECURRENCE INTERVAL OF BANKFULL DISCHARGE, IN YEARS
(PARTIAL DURATION SERIES)
0.5 1.0 1.45 2 5 10 20

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Yampa River
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1.01 1.05 1.10 1.25 1.50 2 5 10 50
RECURRENCE INTERVAL OF BANKFULL DISCHARGES, IN YEARS
(ANNUAL PEAK SERIES)

Fig. 12. Distribution of bankfuU-discharge-recurrence intervals.

SUMMARY AND CONCLUSIONS

The effective discharge is defined as the increment of discharge that trans-
ports the largest fraction of the annual total sediment load over a period of
years. The effective discharge was computed at 15 gaging stations in the Yam-
pa River basin. As suggested by Wolman and Miller (1960), the effective dis-
charge is a relatively frequent event. At the stations studied, the effective dis-
charges were equaled or exceeded on the average between 1.5 days per year
(0.4% of the time) and 11 days per year (3.0% of the time).
The variation in the duration of the effective discharge between stations
is explained, in part (about 50%), by the skewness of the distribution of daily
streamflows. As the size of the contributing drainage area decreases, the rela-
tive abundance of high flows or skew of the distribution of streamflows in-
creases. AB a result, the effective discharge becomes less frequent as drainage
i area decreases.
I
i Conceptually, the duration of the effective discharge should also be in-
:
\, fluenced by the threshold of sediment transport. For the streams studied,
(i however, there was no apparent correlation. In all streams, regardless of how
lcoarse the median diameter of bed material, there was some relatively fine

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