FLOOD07468

• County: Statewide
• Community: State of Colorado
• Stream Name: All
• Basin: Statewide
• Title: The Design of Encroachments on Floodplains Using Risk Analysis
• Date: 10/1/1980
• Prepared For: USDOT
• Prepared By: Federal Highway Administration
• Floodplain - Doc Type: Educational/Technical/Reference Information

TABLE OF CONTENTS

e

SECTION SUBJECT

Preface

Acknowledgements

.

1.0

Introduction
1.1 LTEC and Traditional Design Concepts
1.2 Function of Design Elements
1.2.1 Design and Overtopping Discharges
1.2.2 Freeboard

"

2.0 Preliminary Analysis of Project Risk

3.0 LTEC Design Procedure

4.0 Selection of Alternative Designs

5.0 Analysis Considerations
5.1 Limiting Assumptions
5.2 Useful Life of Structure
5.3 Discount Rate

6.0 Data Collection and Analysis
6.1 Data Collect i on
e 6.1.1 Land Use Data
6.1.2 Flood Plain Geometry
6.1.3 Hydrologic and f~draulic Data
6.1.3.1 F1 ow ~.1agnitudes
6.1.3.2 ilydrographs
6.1.3.3 Fl O\~ Resi stance
6.1.4 Geologie and Soils Data
6.1.4.1 Channel ~10 rp 110 1 Ggy
6.1.4.2 Soils Information
6.1.3.3 Scour Hi story
6.1.5 Construction Costs
. 6.1.6 Traffic Data
6.1.7 Embankment and Pavement Repair Costs
" 6.2 Hydrologic and Hydraulic Data Analysis
. 6.2.1 Flood Frequency
6.2.2 Water Surface Profiles
6.2.3 Stage-Discharge Relationship
6.2.4 Overtoppi ng Depths and Times
6.2.4.1 Overtopping Depths
6.2.4.2 The USGS E431 Method
6.2.4.3 3asic Graphical i1ethod
6.2.4.4 Short-cut Graphical Method
6.2.4.5 Overtopping Times
6.2.5 fiydrographs
6.2.5.1 Using a Measured l~drograpl1 as a Pattern
e 6.2.5.2 Computed I~drographs

iii