FLOOD04641

• County: Denver
• Community: All
• Stream Name: All
• Basin: South Platte
• Title: Proposed Hydrology for use in Hydraulic Analysis of FEMA Flood Studies and Restudies
• Date: 9/1/1989
• Prepared For: State of Colorado
• Prepared By: Resource Consultants
• Floodplain - Doc Type: Educational/Technical/Reference Information

I

I

I

I

I

I

I

I

12.0

I

I

I

I

I

I

I

I

I

I

I

TABLE 1L-l -=- SUMMARY OF l'ii fEAK DISCHARGES !IT RQl
DRAINAGE AREA PEAK DISCHARGES(l) llfi.l
1.0CATION ( square mUm 10 YR 2QYR 100 YR 500 YR
P 1 1. 64 30 50 70 100
P 2 2.12 50 110 140 240
P 3 2.29 160 270 340 500
P 4 0.70 20 70 120 NA(2)
P 5 1.00 190 330 440 660
P 6 2.39 280 430 540 730
P 7 3.86 550 910 1,170 1,700
P 7a 3.96 550 920 1,190 1,800
P 8 5.00 440 910 1,280 2,160
P 8a 5.10 450 920 1,290 2,220
P 10 9.99 840 1,530 2,060 3,300

(1) These values result from the 2l,-hour AMC II storm.
(2) The SOD-year discharge was not determined for points outside the
study reach.

WINDMILL GUll!! HYDROLOGY

12.1 Watersh"d DescrIption

The Windmill Gulch basin (UG) is located in Security as shown
in Figure 12.1. The channel runs from Security Creek (along
Security Boulevard) northeast approximately 4 miles into the
southern portions of the Colorado Springs Peterson Field
aIrport property. Recent development has constructed an
outfall to bypass flows from WG past Security Creek and into
Fountain Creek. In addition, development has created two
detention ponds on WG to control flood flows.

The drainage area to the confluence of Security Creek Is 5.43
square miles. The watershed is in moderately rollIng terrain
with th" lower portions of the basin urbanized. The average
slope of the watershed is approximately 2%, with slopes rangIng
from less than 1% to over 4%. The upper portions of the
waterShE!d are currently undeveloped and consist of rangeland
and dryland farming. The soils are sandy and the vegetation
cover is generally good. Most soils are sandy and permeable
and are classified as "A" (SCS hydrologic soil classification),
with the eastern portIon of the basin having higher clay
content and classified as "BI1.

The Canal #4 crosses through the middle portion watershed and
carries water southeast to Big Johnson Reservoir located in the
Cruz Gulch immediately adjacent to the WG watershed. ThIs
canal crosses the WG channel approximately one-half mile north
of Bradley Road. The canal captures the low flows of WG and
was assumed to be overtopped for the 10-, 50-, and 100-year
hydrologic analysis. Some storm drainage does enter the basin

50

R€~OURC€ CON~UlTI\NT~ INC