FLOOD00403

• County: Statewide
• Title: Hydrology of a Highway Stream Crossing
• Date: 10/1/1979
• Prepared By: USDOT
• Floodplain - Doc Type: Educational/Technical/Reference Information

TABLE 2

Probability that Selected Time Periods will Include One
or More Maximum AnnOdl Peak - QIO' Q20' ~SO or Q12S

A.

QIO - 13,000 c.f.s.

c. QSO. 23,000 c.f.a.

t

, VTo" ~ IC vr. ?n vrA~
1. Periods with One or More !. 61 40 i 20 11. Periods with One or More 20 ! 20 , 14
I
Max. Annual Peak ~ QIO I; I Max. Annual Peak ; QSO i
:
2. Total Periods in 1000 yrs I 100 ! SO 20 2. Total Periods in 1000 yrsh 100 : SO 20
! I
0
3. Observed Probability I Observed.ProbabUity i
I I 3. 10.20 .
- (1) + (2) I 0.61 I 0.80 1.00 - (1) : (2) 0.40 0.70 .
4. Theoretical Probability , 0.64 ; 0.8R 0.99 4. Theoretical Probability i 0.L8 0.33 0.64
I ,
o. j
B. Q20 - 17,000 c.f.s. D. Q12S - 28,000 c..f.a.
I I
;
1- Periods with One or More 1. Periods with One or More I
llax. Annua 1 Peak > Q 20 40 31 20 llax. Annual Peak; Ql2S I 8 8 8
2. Total Periods in 1000 yrs 100 SO 20 2. Total Periods in 1000 yr. 100 SO 20
.
3. Observed Probability 0.40 0.62 1.01 3. Observed Probability 0.08 0.16 0.40
- (1) ;. (2) - (1) + (2) I
.
4. Theoretical Probability I 0.40 0.64 0.9 4. Theoretical Probability 0.08 0.15 i 0.35
I I i

Lenath of Period

Lenath of Period

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