PERMFILE120564

• Permit No: C1981020A
• IBM Index Class Name: Permit File
• Doc Date: 11/4/2002
• Section_Exhibit Name: Appendix M‎(i)‎ to M‎(viii)‎
• Media Type: D
• Archive: Yes

• ESTIMATE OF FLOOD CHARACTERISTICS FOR EAST SALT CREEK
NEAR MACK IN SALT CREEK DRAINAGE BASIN,
MESA AND GARFIELD COUNTIES, COLORADO
Procedure for ungaged sites with streams in mixed population
flood areas:
1 - Compute basin and climatic parameters separately for parts
of drainage area lying in mountain and lower flood regions:
Mountain Region Southern Plateau Region
Drainage area A = 24mi2 (planimetered) A = 173mi2 (planimetered)
Mean annual PPT. P = 21.4 inches
Z - Compute mountain region flood characteristics from Table 2:
Peak Discharges of Selected STD Error of Estimate, 8
Recurrence - Interval Floods Average Range
• 0
815
1
592
a10 - 0.12 .
'
=
(21.4)
(24) 210cfs 39 +46 to -32
450 - 0.91 (24)0.795(21.4)1.110 = 341cfs 37 +44 to -30
4100 = 1.88 (24)0.787(21.4)0.932 = 398cfs 38 +45 to -31
4500 - 8.70 (24)0.766(21.4)0.560 = 552cfs 45 +55 to -35
Depths of Selected RI Floods
D10 = 0.44 (24)0.196(21.4)0.347 = 2.4 ft 27 +31 to -23
D50 = 1.05 (24)0.192(21.4)0.133 = 2.9 ft 28 +31 to -24
D100 - 1.44 (24)0.187(21.4)0.059 = 3.1 ft 28 +32 to -24
D500 - 1.94 (24)0.184 = 3.5 31 +36 to -26
3 - Compute flood characteristics for Southern Plateau region
from Table 4:
n
U