FLOOD07394

• County: Adams
• Community: Adams County
• Stream Name: Niver Creek
• Basin: South Platte
• Title: Niver Creek Community File
• Date: 1/1/2001
• Prepared For: CWCB
• Prepared By: CWCB
• Floodplain - Doc Type: Community File

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point 1 is approximately 20%.

This can be attributed to the differences

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,differen1e can
pervious 'area.
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field Creek basin. The basin perviousness for Northfield Creek was I

5~and the basin perviousness for Little Dry Creek basin was approximatelJ

60%. For the Thornton study there is a very large difference. This ~

be attributed to a different philosophy regarding im-~/?

This study used an imperviousness Of~% while the I

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Thornton study used an imperviousness of 25%. The Thornton study ~d
(Z..ooF-:::, AO .p'l'io..u--./'o......... AlZ..\'a.A ;q~ 11-\'=.1 Dtz..A.A-l,.) "t; 'HE. .;");..;.~C.vp.;ll::::>i~t..'7
3.R i..-1e-.....;..,,';,,~~- -f a;rea a6 Ll.c.y dr::tin t.o t.he I3HrrGl.lpoin-<] pr:evious

in basin perviousness between the Little Dry Creek basin and the North-

lawns. SOr only streets and parking lots were considered as impervious

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fIf,.. area.
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Another source of difference can be attributed to Little Dry

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Creek hYdr~ using the CUHP method while the Northfield Study
used HEC-l~ \:For Niver Creek, the correlation between this study and

data from Little Dry Creek and UD&FCD Niver Creek was not as good.

The reasons for this difference come from three sources. First, the

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basin perviousness percentages are different. The UD&FCD Study had

an existing perviousness of 65% in 1973 while this study shows a

basin perviousness of 63%. For comparison, these values were compared

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to the fully developed perviousness of 48% (from UD&FCD Phase B Report).

Second, the UD&FCD Study uses the CUHP method of runoff determination

while this study used the Corps of Engineers HEC-l program. Third,

for this study the newer Ct and Cp values were used.

These new values
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were released in July, 1975 after the completion of the UD&FC9^Report.
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For Niver Creekr the ef[~~t was t.hat. both Ct and Cp were significantly

higher; .47 and .63 versus .31 and .51 respectively. -r(!.- '1" !j / "'f' It

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