BACKWATER AT BRIDGES AND DENSELY WOODED FLOOD PLAINS, TALLAHALA CREEK AT WALDRUP, MISSISSIPPI

by B.E. Colson, C.O. Ming, and George J. Arcement

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Atlas HA-590

Prepared in cooperation with the Department of Transportation Federal Highway Administration and the Mississippi State Highway Department 1978

Atlas HA-590, Sheet 1

TABLE OF CONTENTS

Introduction
Hydrologic Investigations Atlas Number
Description of Data
    Type of Data
High-water Marks
Bridge Geometry
Manning's Roughness Coefficient
Presentation of Data
Datum
Flood Frequency
International System of Units (SI)
Data for Tallahala Creek at Waldrup, Mississippi
Flood of April 14, 1969
Flood of February 21, 1971
Flood of April 13, 1974
Summary
Additional Information
Selected References

FIGURES

1. Index map of study sites in the bridge backwater investigation project, Alabama, Louisiana, and Mississippi.
2. Index map showing study reach, Tallahala Creek at Waldrup, Mississippi
3. Aerial view looking downstream at bridge on State Highway 528, at Tallahala Creek at Waldrup, Mississippi
4. Frequency of floods, Tallahala Creek at Waldrup, Mississippi

TABLES

1. Valley cross section data for Tallahala Creek at Waldrup, Mississippi. Zero station is at the left edge of the valley (facing downstream).
2. Discharge measurement of April 14, 1969, Tallahala Creek at Waldrup, Mississippi. Zero station is at the edge of the left abutment (facing downstream).
3. Discharge measurement of February 21, 1971, Tallahala Creek at Waldrup, Mississippi. Zero station is at the edge of the left abutment (facing downstream).
4. Discharge measurements of April 6, 1964, Tallahala Creek at Waldrup, Mississippi. Zero station is at the edge of the left abutment (facing downstream).
Atlas HA-590, Sheet 2A
Atlas HA-590, Sheet 2B

Locations of representative ground elevations are shown. These are points of significant changes in cross- section elevations and alignment of the axis. Plots of cross sections are graphic presentations of the tabular data. Bridge geometry and road embankments are also shown as they existed at the time of the floods. Manning's roughness coefficient values and April 13, 1974, flood boundaries are shown.

Atlas HA-590, Sheet 3A
Atlas HA-590, Sheet 3B

Atlas HA-590, Sheet 4A
Atlas HA-590, Sheet 4B

Atlas HA-590, Sheet 5A
Atlas HA-590, Sheet 5B

ABSTRACT

New techniques for predicting water-surface profiles, needed in the design of economical, structurally sound, and environmentally compatible stream crossings, are under investigation. The investigation has accelerated with the advent of digital computers capable of analyzing large quantities of data. Among the techniques is the development of two-dimensional (2-D) digital models. Field data are essential for development and evaluation of these techniques for predicting water-surface profiles. This atlas is one of a series that provides a wide range of field data.

Since 1969, the U.S. Geological Survey has been collecting backwater data where wide, densely vegetated flood plains are crossed by highway embankments and single-opening bridges. This work was done in cooperation with the Federal Highway Administration Department of Transportation, the Alabama State Highway Department, the Louisiana Department of Transportation and Development, and the Mississippi State Highway Department. The objective of this cooperative project is to present the data in a format conducive to the development of improved models for predicting hydraulic responses of flow at highway crossings of streams in complex hydrologic and geographic settings.

Backwater data were obtained at 22 sites for 35 floods; that is, 11 sites had 1 flood each; 9 sites, 2 floods each; and 2 sites, 3 floods each. Analysis of data showed that backwater and discharge at these sites computed by methods presently in use, would be inaccurate. The floodflow data are unique in the range and detail in which information was collected and provide a base for evaluating digital models relating to open-channel flow. This atlas shows flood data obtained on Tallahala Creek at Waldrup, Mississippi, one of the 22 sites.


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