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

I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I

CHAPTER III
HYDROLOGIC N1ALYSIS

of design point S-2 designates the downstream limit of sub-basin S-2.
Design point S-2.3 designates the downstream limits of the third sub-
division of sub-basin S-2, and design point S-2.32 designates the downstream
limits of the second sub-division of sub-basin S-2.3.
Figure 11-1 shows the location of the desino, points and the limits
of the sub-basin boundaries for the 1st Avenue Tributary and the ~akota
Avenue Trib~ltary. Figure 11-2 S'lOWS the location of the design points and
the limits of the sub-basin bounJaries for the Oepew Street Basin.

A. GENERAL
The hydrologic analysis discussed in this chapter starts with the
subdivision of the major drainage basins into sub-basins so that storm
runoff peaks and volumes can be defined for each sub-basin and hydrologic
point of interest. Design flows thus developed are used to evaluate
existinCl facilities, limits of ootential flood damaoe, ann rlrainaoe
improvements. Current U. D. ?< F. C. D. procedures were used to deve 100 peak
discharoes and volumes at each design point for the 5-, 10-, 50-, and
llJO-year recurrance interval for future development conditions aw' for
the lOO-year recurrance interval for existing develooment conditions.
ExistinCl facilities were evaluated usinCl the developed design dischar'les.
Rased on the recommendations in the Phase ~, Reoort the l,)O-year
recurrance interval was selected as desi gn frequency for proposed imorovements.
I!sino, the above mentioned procedures design flows were developed for each
sub-basin and hydrologic point of interest to analyse the impact of the
proposed improvements.

C. RAINFALL DATA

For a storm havi ng a durati on of three hours, 1.1hi ch was the maximum
duration storm used in the analysis, the rainfall intensity was assumed
to be the same for anyone time increment and also uniformly distrihutecl over
the entire drainage basin. The values listed below for rainfall de'lth are
taken from project "REUSE" (7) for Jefferson Countv, HS, R69~J, and were
used for both drainage basins.

TABLE 111-1
RAINFALL DATA

1>. DESIGN POIf'lTS AND SU[l-RASH4 DELmEATION
The following parameters were used in defining the limits of the
sub-basins:
1. Jurisdictional boundaries;
2. Major difference in land use and ground cover;
3. Locations of specific hydroloQical or hydraulic problems.

Depth (Inches)
Frequency 1 Hour 6 Hours
2-Year 0.68 1. 12
lr)-Year 1. 51 2.50
50-Year 1.33 3.16
lOO-Year 2.IJr) J.50

Fi 'Jure II 1-1 S'lOWS the Rai nfa 11 r)epth-Durati on- Frequency Graphs developed

for the study area. Tables 111-3 and 111-4 present the design storm

preci pi tati on.

The location of the desing points also defines the dm~nstream limit
of the drainage sub-basin with the same number. For example, tbe location

111-1