FLOOD04642

• County: Mesa
• Community: Delta
• Stream Name: Gunnison
• Basin: Gunnison
• Title: Floodplain Information Report
• Date: 4/1/1996
• Prepared For: Mesa County
• Prepared By: CWCB
• Contract/PO #: &&
• Floodplain - Doc Type: Floodplain Report/Masterplan

TABLE OF CONTENTS

Preface

LIST OF FIGURES

1.0 INTRODUCTION. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 1
1.1 Purpose'. . . ',' . . . . . . . . . . . . . . . . . . . . . . . . ... . . . . . .. . . .-.,'. . .. 1
1.2 Acknowledgements. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 1
1.3 Related Flood Studies ..................................... 1

FIGURE
1 Location of Upper Colorado River Basin
2 Location of Gunnison Drainage Basin in Colorado
3 Gunnison Dniinage Basin Map
4 Location of Study Reach With Hydrologic Points
6 Location of Reaches Within Study Area
7A-H Cross-Sections With Flood Elevations
8 Base Map Topographic Index and Scale
9 Index Map of Plates

2.0 STUDY AREA .............................................. 2
2.1 Location. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 2
2.2 Study Reach ........................................... 2
2.3 Basin Characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 4
2.4 Summary of Drainage Areas ................................ 4
2.5 Flood Characteristics. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 6

3.0 HYDROLOGIC ANALYSIS ..................................... 9

3.1 Existing Data. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 9
3.2 New Hydrologic Information ................................ 9
3.3 Hydrologic Findings. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 9

PLATE
1-7
8-10

Approximate Flooded Area Maps
Elevation Discharge Curves

4.0 HYDRAULIC ANALYSIS ..................................... 12
4.1 Base Mapping ......................................... 12

4.2 Stream Reaches ........................................ 12
4.3 Field Surveys and Cross-Section Preparation .................... 15
4.4 Computing Flood Depths. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . " 16
4.5 Delineating Flood Boundaries . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 17

5.0 INTERPRETATION OF THIS REPORT. . . . . . . . . . . . . . . . . . . . . . . . . . .. 20
5.1 Hydrologic Findings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 20
5.2 Hydraulic Findings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 20
5.3 Floodplain Delineations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 20

6.0 REFERENCES. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 21

"

LIST OF TABLES

TABLE
1 Stream Gage Data
2 Drainage Area Summary
3 Flow Summary
4 Reach Classification
5 Cross-section Summary
6 Depth of Flooding Summary

PAGE
2
6
10
13
16
18

iii

ii