FLOOD00801

• Designation Number: 182
• County: Arapahoe
• Community: Cherry Hills Village
• Stream Name: Blackmer Gulch Tributary
• Title: Flood Hazard Area Delineation - Blackmer Gulch Tributary, Cherry Hills Village, Colorado
• Date: 8/1/1981
• Designation Date: 12/4/1981
• Floodplain - Doc Type: Floodplain Report/Masterplan

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Table 1

Table 1

SUMMARY SHEET
BLACKMER GULCH TRIBUTARY HYDROLOGY

COrmNUED

STORi'l HYDROGRAPH CHARACTERISTICS - FUTURE CONDITIOnS

100-Year Precipitation - 3.19 inches - 120 minute duration

Hydrologic
Point
1

lOO-Year Storm
Peak - CFS Volume Acre-feet)
3 4

RAINFALL DATA

Pervious Area

- Infiltration rate = 0.08 inch/10.minutes
Detention and depression storage = 0.30 inch
Effective precipitation = 1.94 inch

#1 El Camino St.

2.40
2.33

418.5

24.1

#2 Blac~TIer Lake

539.3

59.2

Impervious Area

- Depression and detention storage = 0.05 inch
Loss = 0.15 incr.
Effective precipitation = 2.99 inches

LEGEND OF ABBREVIATIONS

BASIN CHARACTERISTICS
Hydrologic Area Length = L Length = Lca
Point Acres Miles Mil es
1 2 3 4
#1 El Camino St. 121.9 0.44 0.15 82 56
#2 Blackmer Lake 305.0 1.42 0.87 32 64
UNIT HYDROGRAPH CHARACTERISTICS
Hydrologic
Point
1
#1 El Cami no St. 0.41 0.53 0.22 18.1 0.32 0.17 1548.8 295.0 10.1
#2 Blackmer Lake 0.53 0.60 0.56 38.9 0.74 0.38 679.6 323.9 25.4

L = Length along stream from study point to upstream limits of the basin
in miles.
Lca Distance from study point along stream to the centroid of the basin
in miles.
Ct = A coefficient reflecting time to peak.
Cn = A coefficient related to peak rate of runoff.
tp = Time to peuk of hydro<Jr~ph frolTlmidpoint of unit rainfall in hourc"
Tp - Time frolTl hl'ginnin'l of unit rilinfilll to pt'ilk Of f1ydroflrdph ill IlIintJl,p'i.
W50 = Width of unit hydrourrlph <It 50 pt,rcent or pI'llk di',cI1r1r'l",
W75 l.idUI of unit hydrourapll ill. 7~) pere<:nt of ",'ak discll<lr'l'"
qp Peak rate of runoff in CFS per square lIIi 1 e.
Op 0 f1aximUIII unit hydrograph peak in CFS.

IWTE: Hydrological studied based on the Co10rarlo Urban Hydrogranh Procedure-
as presented in the l!,rball_.?toJ:1I1 g_r.al!laJle~ _Cri.t.e!j_a_t~an_u.a.1.

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