FLOOD00764

• County: Statewide
• Community: Nationwide
• Title: Use of Extreme Value Theory in Estimating Flood Peaks from Mixed Populations
• Date: 2/1/1980
• Prepared By: Utah State University Water Research Laboratory
• Floodplain - Doc Type: Educational/Technical/Reference Information

The associated river heights (Q(T)) as
eSllmaled by Equation 12 using the respective
parameters in Table 6 are shown in Table 10.
The goodness-of-f it stat ist ics are tabulated
In Table 12.

It is instructive to view the plots
of these rivers. Shown in Figures 19 to 29
are the plots for each river. The Cl
axis is In(b-X(i)) and the CL axis is
10(-ln(i/(n+l)). The maximum likelihood
estimaled value of b has been used.

The Saguenay River (Figure 19) manifests
a straight line plot and may have nearly
homogeneous sources, although the two largest
floods could be from another source. The
Niger River, location Dire (Figure 20)
and locat ion Koul ikoro (Figure 21), exh ib i ts
two sharply different components. The
Penobscot River (Figure 22) appears to have
homogeneous sources with close to a straight
line plot. Figure 23 does not exhibit a
clear indication of two sources, although
there seems a tendency toward two straight
lines. Ils estimated parameters indicate
likewise, a = 2.30 and a' = 2.30 with c =
388.32 an c' = 410.86--very close to identi-
cal components. The Vuoksi River (Figure 24)

Table 6. Maximum flood flow b (in m3 /S), scale
factor .sf, and parameters estimated
from Equation 25.
No. b sf "I "2 81 82
1 25000 22630 16.33 8.67 4.26 0.001
2 3000 1053 3.53 719.68 3.74 0.52
3 21000 17354 14.05 14.05 0.14 6.06
4 18000 17179 0.91 27.57 0.005 2.92
5 700 562 2.30 2.30 2.34 2.06
6 2500 2167 14.55 2398.16 9.82 4.90
7 6000 5293 22.89 6.69 2.06 1.40
8 1300 1047 6.55 6.59 0.25 11. 32
9 6000 4000 4.89 6.46 0.02 8.56
10 670 347.9 8.98 1.03 0.013 0.14
11 3100 1200 9.31 0.87 5.6 E-4 0.04

Table 7. Parameter estimates of a, a', c, and
c' for each station.
No. b a a' c c'
1 25000 16.33 8.67 20706.33 49696.00
2 3000 3.53 7.19 724,52 1053.96
3 21000 14.05 14.05 19932.25 15265.06
4 18000 0.91 27.57 5605113.20 16523.166
5 700 2.30 2.30 388.32 410.86
6 2500 14.55 2989.16 1852.06 2165.81
7 6000 22.89 6.69 5128.49 5033.41
8 1300 6.55 6.59 1297.56 724.48
9 6000 4.89 6.46 8904.89 2869.71
10 670 8.98 1. 03 563.86 2303.15
11 3100 9.31 0.87 2683.34 49293.56

Table 8. Data values D(T) (in m3/S) as inter-
polated between adjacent observa-
tions by the Chegodayev method.
T in Years
No. 2 5 10 20 50 100
1 4655 6125 6766 7811 9166 a
2 2335 2562 2641 2664 2677 a
3 6250 7066 7670 9065 9590 a
4 1738 2342 2342 3124 3929 a
5 454 545 578 614 648 a
6 703 794 881 933 1139 1157
7 1350 1875 2418 2759 3474 a
8 627 726 773 809 927 945
9 3300 3762 4000 4118 4500 4560
10 154 252 423 509 622 a
11 540 836 1283 1532 2300 a
8Beyond the range of the data.

Table 9. Data values D(T) (inm3/S) as inter-
polated between adjacent observa-
tions by the Hazen method.
T in Years
No. 2 5 10 20 50 100
1 4655 6111 6761 7714 9128 9244
2 2335 2561 2640 2661 2677 a
3 6250 7041 7649 8964 9552 9676
4 1738 2339 2650 3081 3777 4251
5 454 545 577 614 646 655
6 703 794 880 931 1138 1153
7 1350 1867 2412 2700 3401 3655
8 627 726 733 806 927 937
9 3300 3750 4000 4100 4500 4540
10 154 251 422 498 613 644
11 540 835 1253 1518 2149 2607
aBeyond the range of the data.
Table 10. Data values D(T) (in m3/S) as inter-
polated between adjacent observa-
tions by the Weibull method.
T in Years
No. 2 5 10 20 50 lui)
1 4655 6170 6775 7987 9224 a
2 2335 2563 2643 2670 a a
3 6250 7103 7701 9216 9648 a
4 1738 2346 2673 3188 4156 a
5 454 546 579 615 652 a
6 703 794 881 935 1142 1164
7 1350 1888 2426 2848 3583 a
8 627 727 773 814 927 973
9 3300 3780 4000 4145 4500 4589
10 154 255 425 524 636 a
11 540 841 1310 1567 2528 a
aBeyond the range of the data.
18