FLOOD09590

• County: Arapahoe
• Community: Aurora
• Stream Name: Cherry Creek Lake
• Basin: South Platte
• Title: Hydrologic Improvement Assessment Cherry Creek Lake
• Date: 9/1/1993
• Prepared For: State of Colorado
• Prepared By: US Army Corps of Engineers
• Floodplain - Doc Type: Project

Table 3
PMF Rainfall and Runoff - Cherry Creek Basin
Existin~ Condition Fully DeveloDed Condition
Time Rainfall Losses Runoff Losses Runoff
(hours) (inches) (inches) ilnches) ( inche,u ( inche:u
1-12 .39 ,39 0 .39 0
12-24 .87 .87 0 .87 0
24-36 3.87 3,87 0 3,87 0
36-37 .38 .38 0 .30 ,08
37-38 .63 .50 .13 .30 ,33
38-39 .92 ,50 .42 .30 .62
39-40 1.33 .50 .83 .30 1.03
40-41 2.00 .50 1. 50 .30 1. 70
41-42 2.92 .50 2.42 .30 2,62
42-43 7.83 .50 7.33 .30 7.53
43-44 2.25 .50 1. 75 .30 1. 95
44-45 1. 50 ,50 1. 00 .30 1. 20
45-46 1.00 .50 ,50 ,30 ,70
46-47 .75 .50 .25 .30 .45
47-48 .62 ,50 .12 .30 .32
48.60 1. 38 1. 38 0 1. 38 0
60-72 ~ ~ _L_ ----....21i -L-
29.22 12.97 16.25 10.69 18.53
RESERVOIR ROUTING

Reservoir routings were performed using the Multiple Routing Program or

DAMBRK depending on whether a dam failure was to be modeled.

ROUTING ASSUMPTIONS

The initial pool level in all of the Cherry Creek Reservoir routings was a

half full flood control pool, elevation 5579,0 feet m.B.l,

References used as the basis for selecting a half. full flood control pool

for the initial pool in the routing5 include EC 1110 - 2 - 27 and the Reservoir

Regulation Manual for Cherry Creek Reservoir, In EC 1110-2-27, paragraph llc(5)

it is stated:" ,if the flood control capacity is unusually large in

comparison with normal flood runoff qU<intities, the assumption that the reservoir

will be only half filled at the beginning of the spillway design flood would be

reasonable . II

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