FLOOD00850

• Designation Number: 31
• County: Arapahoe
• Community: Unincorporated Arapahoe County
• Title: Major Drainageway Planning - Little Dry Creek, Report, Volume I
• Date: 2/1/1974
• Designation Date: 6/1/1974
• Floodplain - Doc Type: Floodplain Report/Masterplan

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Table 2

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POINT RAINFALL DEPTHS

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Sub-basin
Designation
(1)

10-Year Freq.
l2G-Min. Duration
Rainfall
(2)

Depth In Inches
25-Year Freq.
l50-Min. Duration
Rainfall
(3)

100-Year Freq.
l80-Min. Duration
Rainfall
(4)

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Little Dry Creek
Lower
Middle
Upper

Greenwood Gulch

2.35 2.80 3.40
2.52 3.01 3.70
2.59 3.03 3.70
2.52 3.01 3.70
2.44 2.82 3.46
2.44 2.82 3.46
2.59 3.03 3.70
2.59 3.03 3.70
2.65 3.10 3,88
2.70 3.l9 4.00

Quincy Gulch

Blackmer Gulch

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Prentice Gulch

Willow Creek

Spring Creek

Cook Creek

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Rainfall durations shown in the Table 2 headings are the durations used for

hydro graph analysis as determined from an inspection of some 68 Denver

area rain storms. The point rainfall amounts taken from the source

data were reduced by an area correction factor for sub-basins larger

than five square miles.

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The time rate of accumulation of rainfall depth was also determined

from the study of Denver area rainstorms. Rainfall accumulation was

divided into 10-minute increments for each storm duration, and a typical

storm pattern was determined. The total rainfall amounts for the 10,

25 and 100-year rains were distributed according to the typical rainfall

pattern for the development of runoff hydrographs for each sub-basin.

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