FLOOD07072

• County: Statewide
• Stream Name: South Platte
• Basin: South Platte
• Title: Water and Related Land Resources Management Study Volume IIIC - Appendix A
• Date: 7/14/1980
• Prepared For: South Platte and Tributaries
• Prepared By: CWCB
• Floodplain - Doc Type: Flood Mitigation/Flood Warning/Watershed Restoration

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used on the flows at the Denver, Henderson and Kersey stations

because it more nearly reflected the bias introduced by regulation

at these stations. The longer records at Kersey and Julesburg

were used to extend respectively the shorter records at Weldona

and Balzac. The correlation coefficients between Kersey and

Weldona and between Balzac and Julesburg were 0.95 and 0.74

respectively. The record extensions were 35 years for Weldona

and 7 years for Balzac. A zero skew coefficient was used at all

stations except Balzac. Its proximity downstream from the mouth

of Bijou Creek, which has experienced frequent extreme flooding,

resulted in a computed skew slightly less than +0.5. Adjustments

for expected probability were based on the total years of record,

or, in the case where the extension of record was used, the

expected probability adjustment was based on the equivalent years

of record. Because of the positively skewed distribution used at

the Balzac station, no expected probability adjustment was used

at this location. This was in accordance with procedures prior

to publication of the Water Resources Council Bulletin 17. The

Balzac curve has not been revised, however, since the expected

probability adjustment was less than 8 percent at the 100-year

level. All curves were adjusted to partial duration by using an

annual series-partial duration relationship developed by Langbein.

The adjusted curves are shown on plates 18 through 23. A summary

of pertinent statistical parameters is shown in table 7.

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