FLOOD00189

• County: Denver
• Community: Denver, Lakewood
• Stream Name: Weir Gulch Tributaries
• Title: Major Drainageway Planning
• Date: 7/1/1978
• Prepared For: Denver County
• Prepared By: UDFCD
• Contract/PO #: &&
• Floodplain - Doc Type: Floodplain Report/Masterplan

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F req uen cy
All Frequencies

First 1/2 Hour
0.5 inch/hour

Second 1/2 Hour
to End of Storm

1).5 inc~/hour

the Colorado Urban Hydrograph Procedure. Oesign hydrographs for the Phase A
Study were calculated using the computer program developed by Leonard Rice
Consulting Water Engineers. For Addendum One to the P~ase A Study and for
refinements required in the Phase B Study the co~puter progra~ developed by
the Urban Orainage an1 Flood Control Oistrict "Ias used. Suh-basin hydrograp!ls
were routed downstream to the next design ooint hy using the estimated travel
ti~e in the reach between the two design points.
The Puls method was used to calculate discharges at locations where
storage has a significant effect.
Design point hydrographs are shown in Figures 111-2 and 111-3.
Design flows between design points were taken from the discharge probahility
curves shown on Figures 111-4 thru 111-6.

Losses
Based on the recommendations given in the "Urban Storm Drainage Criteria
Manual", the following criteria for losses ~Iere applied to calculate the
runoff from the rainfall data:
1. Infi ltration:

2. Detention and Depression Storage:
Impervious Area - .05 inch total
Pervious Area - .3 inch total

3. Residual Loss for Impervious Area:
Five percent of incremental rainfall minus detention and deoression storage.

areas.
Commercial and un,:eveloped areas were esti~aterl separatelY, using the
recommended val ues from the Urban Storm Orai nage Criteri a ~~anual.
Drainage hasin parameters and associated peak flo\'ls are sho"ln in
Table 111-2.

F. DISCHARGF PROBftBILITY PROFILES
!lis charge probability profiles for the !lakota Avpnue and 1st Avenue
Tributaries preoared for the Phase ft Reoort are s~own in Figures 111-7
and III-8. They orovide future condition discharGe values for return
oeriods of 5, 10, and 50 year future and Ino year prpsent basin development
condi ti ons.
The future 100 year return oeriod discbaroe profiles are shown on
Fioure 111-5 and 111-6.

D. ORAFlAGE SAS IN P ARA~IETERS
The percent of imperviousness of the total area was estimated by
applying the percent of imperviousness esti~ated for a residentially
developed area assumed to be typical. This area is hounded by Second Avenue
on the south, Quay Street on the west, and Pierce Street on tile east.
Calculated values for this area were used for other sirlilarly developed

E. FLOOD FLOVJS AND DESIGN HYDROGRAPHS

For each sub-basin, a design hydrograph was calculated in accordance with

111-2