USGS

Computation of Water-Surface Profiles in Open Channels

U.S. Geological Survey, Techniques of Water-Resources Investigations, Book 3, Chapter A15

By Jacob Dividian


Table of Contents

Preface

Abstract

Introduction

Hydraulic ptrinciples

Steady, uniform flow

Backwater curves

Transition curves

Determination of normal depth

Average profile in a long reach

Use of Ml and M2 curves

Use of S2 and S3 curves

Local effects on profiles

Convergence of backwater curves

Special cases of backwater curves

Flows on very small slopes

Flows on steep slopes

Locus of critical-depth stages

Control sections

Transitions between tranquil and rapid flows

Alternate depths

Energy equation

Standard step method

Subcritical flows

Supercritical flows

Field data

Total reach length

Locations of cross sections

Individual subreach lengths

Weighted length of a subreach

Cross-section attributes

Subdivisions of cross sections

Velocity-head coefficient, alpha

Roughness coefficients

Special field conditions

Verified reaches

Short reaches

Crossing profiles

Transitions between inbank and overbank flow conditions

Flow at tributaries

Flow past islands

Multichannel flows

Bridges

Flow through culverts

Road overflow at culverts

Storage at culverts

Multiple-opening constrictions

Division into single-opening units

Two-bridge openings

Three or more bridges

Alluvial channels

Use of step-backwater method for indirect discharge measurements

Floodway analysis

Encroachment of cross sections

VER option

VSA option

VHD option

HOR option

Selected references

 


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