FLOOD09354

• County: Douglas
• Community: Douglas County
• Basin: South Platte
• Title: South Platte River Post Wildfire Floodplain Study, Hayman Burn Area, Douglas County
• Date: 11/24/2004
• Prepared For: CWCB and Douglas County Public Works
• Prepared By: Anderson Consulting Engineers
• Floodplain - Doc Type: Floodplain Report/Masterplan

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TABLE OF CO:\'TE:-;TS

I. II'TRO DUCTIOl'\ ,....,~......~.. ....~.~.~...~.. ~... ..~..~.... ~...~.~...............~.~....'"'''''''''''''''''''' I

1.1 Background.... ........................ ....... ........ ....... ..,. ....... ....... ... ... ................................ ....1
1.2 Previous Studies...... .... ............... '.'. .... ........... .......... ....... ............. ....... .... ..... .... ..... ....1

II. TOpOGRAplIIC BASE MAP AJ'D FIELD SURVEYII'G...~...~~~~~.........,.........,.... ....4

2.1 Topographic Base Map.... ........ ..... '.. ... ........ ... ... .... ....... .... ... ... ................... ......... ......4
2.2 Field Surveying.. .... .... .................. '.............. ........................ .......... .... .... ... ...... ..........4

I II. HYD RO LOG Y .~ ~~.~.~...~....,........... ~..~...~.~.......,....~..~ .~~ ~.~..~ ~..~. ~...............,...........6

IV. I IYDRAULIC ANALYSES ~..~..~.~,............~..~.~..~.~..~...,...........~..~.~.~.~..~...~...........8

4.1 Assessment ofChanncl and Floodplain Roughness Coefficients.m........................8
4.2 Description of Hydraulic Models...........................................................................12
4.3 Cross Section Geometry ........................................................................................12
'::.4 Road Crossings/Bridges........... ... ............... .............. .... ... ............. ......................... .13
4.5 Boundary Conditions .............................................................................................16
4.6 Flood\va y Analysis. ........... .... ............... ... ....... .......... ................. ... .... ........ .... ......... .16

V. HYDRAULIC MODELIl\G RESULTS ...........................................................................17
VI. FLOODPLAIN AND FLOODW A Y MAPPI:\G ..............................................................22
VI I. REFEREJ'CES ......~.........~. ~~.~. ~. ~.. ~......~........~ ~~.~.~..~. ~"~"""''''''''''''''''''''~' ~~.~. .23

Figure 1.1

Tabld.1

Table 4.1

Table 4.2
Table 4.3
Table 5. I
Tabk 5.~

LIST OF FIGURES

Vicinity Map for the South Platte River Post-Wildfire Floodplain Study...............2

LIST OF TABLES

Summary of Peak Discharges for the South Platte River
fronl \Vig\varn to South Platte........................................................................... ......7
Summary of Ground Cover Types and Manning's Roughness Coefficients
for Overbank Areas along the South Platte Riwr....................................................9
Summary of Manning's Roughness Coefficients for the South Platte River ........10
Summary of Hydraulic Cross Section Locations. Source & Adjustlllem..............14
Tabular Waler Surface Profiles for the South Platte River....................................18
Floodway Results for the South Platte River.........................................................20

A,drR'>O' CO.....dlhG hGi'HR", he.

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