FLOOD10386

• County: Jefferson
• Community: Golden, Lakewood
• Stream Name: Upper Lena Gulch
• Basin: South Platte
• Title: FHAD - Upper Lena Gulch
• Date: 1/1/1993
• Prepared For: UDFCD
• Prepared By: Boyle Engineering Corporation
• Floodplain - Doc Type: Floodplain Report/Masterplan

HYDROLOGY

III.

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I

145

to

from 30 acres

ranging In size

The study area was divided into seventy-seven sub-basins

I

the sub-basin delineation

Figure 3 presents

acres

The average sub-basin size is 81

acres

from USGS 7.5

measured

and slope were

Sub-basin characteristics such as area, length

General

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Evergreen

"Arvada'

"Golden

Ralston Buttes"

for

Colorado

maps of

Morrison". and "Fort Logan"

mInute quadrangle

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Lena Gulch above Maple Grove Reservoir for future conditions

Upper

for

Hydrologic analyses

from

Runoff hydrographs

the Urban Drainage and Flood

the procedures outlined in

were conducted in accordance with

I

recurrence Interval

100-year

10. 50, and

the

storms were generated using CUHP. The computer

for

each sub-basin

These analyses

(USDCM)

Urban Storm Drainage Criteria Manual

(UDFCD)

Control District's

I

actual

program CUHPE/PC was used for

1975

Plan. June

update previous studies performed as part of the Lena Gulch Drainaoe Master

as basin

we

were Input to CUHPE/PC as

rainfall depths

One-hour

runoff computations

Ridge. and Jefferson

Wheat

Golden. Lakewood and

the Cities of

for the UDFCD,

prepared

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mpervious area, basin slope. and

to centroid, percent

characteristics such as length. length

County

to develop

the one-hour rainfal

CUHPE/PC used

the basin

to define infiltration in

parameters

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runoff hydrographs for

computed excess precipitation. and developed

a two-hour design storm

Methodolo

Modelin

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A detailed description of the computational procedures

used in CUHPE/PC may be found in the USDCM

routing

combination and

subsequent

runoff has changed significantly over the

The methodology used to analyze and quantify storm

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The basin

the

Plan were performed using

975 Master

for the

The hydrologic analyses

20 years

past

routed to develop discharge hydrographs

runoff hydrographs were combined and

the UDFCD computer

from each basin using

also known as

mode

Model computer

Catchment

Technology

nstitute of

Massachusetts

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program UDSWM2/PC. A complete description

of the UDSWM2/PC program's capabilities and

from information and procedures contained

MITCAT, and used a rainfall distribution developed

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the program's user

mitations may be found in

The currently accepted

(USDCM)

the UDFCD "Urban Storm Drainage Criteria Manual

in

routing the

The UDSWM2/PC program was selected for use In

storm hydrographs because of its ability

from UDFCD

manual available

the Colorado Urban Hydrograph

area is

the Denver

runoff in

computing urban

for

approach

I

to handle a variety of types of conveyance elements as

The methodology

version of the USDCM

the current

which is outlined in

Procedure (CUHP)

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the CUHPE/PC

nterfacing with

its ease of

and because of

well as detention storage facilities

research and practical experience in modeling

the USDCM is based on extensive

presented in

the

Figure 4 presents a schematic diagram of

nput

runoff hydrographs as direct

using

studies of

from

rainfall data derived

area and includes updated

the Denver

runoff in

urban

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hydrologic modeling structure.

area

the Denver

gaged precipitation records in

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4

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