FLOOD03848

• County: Denver
• County: Jefferson
• Community: Denver County
• Stream Name: South Platte River
• Basin: South Platte
• Title: Stream Stability Investigation South Platte River
• Date: 11/1/1983
• Prepared For: UDFCD Denver
• Prepared By: Michael Stevens
• Floodplain - Doc Type: Floodplain Report/Masterplan

Authorization
This studyent1tled "StreamStabil1ty Investigation, South Platte
River," was auth~rized by the Urban Drainage and Flood Control District
on 22 March 1983. As described in the Terms of Agreement No. B3~1.3. the
investigation is divided into two phases. The first, Phase A, was a
background study which consisted of a compilation of facts pertaining to
the nature of the South Platte River and its major tributaries between the
Chatfield Dam a~ Baseline Road immediately north of Brighton. The second,
Phase S, was a study to assess the river's behavior and to predict the
future response of the river to development in the Denver urban area and
to changes in river flows and sediment loads due to construction of the
flood control reservoirs.
Th1sfinal report is a presentation of the Phase A and PhaseB
studies which have been revised to Include data obtained from new maps
and other pertinent infOTmiltfon. Recomnendations concerning future IOOdi~
fications to the river morphology are included in this report.

Purpose and Scope
Phase A. The purpose of the Phase A study was to gather relevant
information from whiCh an estimate can be made of the response of the
So~H, Platte !liver in the Metropolitan Denyer area to future ce\le1op.~nts.
The scope of work for Phase A included the following:

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I. INTRODUCTION

5. Collect and analyze existing data on sediment transport in the
South Platte River and in Cherry Creek, Clear Creek and Sand Creek.
6. Conduct a fluvial morphological study of the South Platte Riyer
.in the study reach and in the lower reaches of Clear Creek and
Sand Creek. The study is to be milde using aerial photographs.
Emphasis is to be focused on the period since the closure of
Chatfield Dam.

7. Prepilre a sumary of the behavior of the study reach of South
Platte River with other rivers in the High Plains Region.
Phase B. The purpose of Phase B was to study the future response
of the South Platte River to existing and future developments affecting
the flow of water and sediment, and to any man-made structures whiCh con~
strain the river's alignment, flood-storing capacity or ability to degrade
its bed. Specifically, the Phase B study included the following:
1. Estimates of expected changes in river stability, alignment, form,
width and bed profile.
2. Estimates of the effects of these changes in the flood-carrying
capacity of the river and on the man-made structures in and
adjacent to the river.
3. Estimates of the effects of these changes on the behavior of Clear
Creek and Sand Creek.

1.

Meet initially and approximately once a month thereafter with.the
representatives of the Urban Drainage and ~lood Co~trol Distrl~t
to ensure compliance, and obtain data and lnformatlon on ex1stlng
and future developments.
Contact the Colorado State Department of Highways; U.S. Army
COrps of Engineers; U.S. Geological Survey; Soil Conservation
Service, County and City Highway Departments and other individuals
or agencies WhO have pertinent knowledge and an interest in the
areaunderconsiderat10n.

4. RecolTTTlendationsforthe improyements to the river to prevent
future damages and to enhance the environment.

2.

5. Discussion of the needs for bank stabflizationtocontrol
alignment and for check structures to control the riverbed grade.
Final Report. The studies were to be completed with the prepara-
tionofafinalwrittenreportconsolidatingPhaseAandPhaseBstudies
into a single document.

Sources of Tnformation
All information and data presented herein have been obtained from
publiShed records in libraries or from files of government agencies in the
Metropolitan Denver area except those which are observations made during
field trips along the river. The sources are referenced in the Text.

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Describe the physical features of each reach of the South Platte
Riverinthestudyareil,includingthosenaturalandman-made
features whiCh affect the study area.
Collect streamflow and flood records for the South Platte River in
the study area. The recods are t~ include annual flows, monthly
flow and the annual flood series. The effects of diversion for
municipal and industrial use and for irrigation and the effects
of regulation on streamflow are to be assessed qualitatively.

Some data presented in the Phase A study are now obsolete and have
been replaced by new data c01lected since that time. For example, the
District has had a 2~foot contour map of the South Platte River from
Chatfield Dam to the Baseline Road bridge prepared from aerial photographs
takeninAprlll9B3. This mapplng replaces cthercnes which are no longer
correct due to development along the river. Also, the U.S. Amy Corps of

4.