hydraulics and stability of tidal inlets tidal tidal tidal inlets 20. abstract (continue on reverse...

i ' ,

1 • •

Hydraulics and Stability of Tidal Inlets

by

Fro ncis F. Esco ffier

GITI REPORT 13

R_~_D ~

August 1977

Prepared for

U.S. Army Coastal Engineering Research Center

under

Contract DACW72-74-C-0005

GENERAL INVESTIGATION OF TIDAL INLETS

A Program of Research Conducted Jointly by

U.S. Army Coastal Engineering Research Center, Fort Belvoir, Virginia U.S. Army Engineer Waterways Experiment Station, Vicksburg, Mississippi

Department of the Army Corps of Engineers

APPROVED FOR PUBLIC RELEASE; DISTRIBUTION UNLIMITED

or republieation of any eredit to U.S.

this publieation available

distribution

National ATTN:

authorized

Drum

United

are not to

the lJ .S.

single Additional

Service

CATALOG NUM8ER

4. TITLE (limd Subtitle) 5. TYPE OF REPORT II PERIOD COVERED

llYDR}\ULICS AND STABT LITY OF TIDAL INLETS inal

6. PERFORMING ORG. REPORT NUMBER

7. AU THOR(o) S. CONTRACT OR GRANT NUM8ER(8)

Franc F. Escoffier DACW72-74-C-0005

9. PERFORMING ORGANIZATION NAME AND ADDRESS 10. TASK

11.

earch Center Belvoir, Vi

F 31019

12. REPORT DATE

2 14. MONITORING AGENCY NAME Ii ADORESS(if different from Controlling Office) 15. SECURITY CLASS. (0/ this report)

UNCLASSIFIED

IS,.. DOWNGRADING

16. DISTRIBUTION STATEMENT (of this Report)

for lie release, distribution unlimited.

17, DISTRIBUTION STATEMENT (of the abstract entered in Block 20, if different from Report)

18, SUPPLEMENTARY NOTES

19. KEY WORDS (Continue on reverse side if necessary and identIfy by block number)

Functional des Inlet

Tidal Tidal Tidal inlets

20. ABSTRACT (Continue on reverse side if neC'$994it'y and

This report presents a summary 0 basic develop- ments to is of the and related stability of tidal inlets. ar, it covers the work Brown ( and Keulegan un inlet ic calculat • and O'Brien (1931, 1966), Jarrett (19 Bruun ( , Johnson (1973), O'Brien and Dean (19 ,and Es coffier ( on the of inlet channel stabU The original inlet tabi concept Escoffier is extended in Ii of recent

DD EotTlON OF I NOV 65 IS OBSOLETE UNCLASSIFIED

UNCLASS TF TEO

work. The report also contains brief discussions on tidal inlet characteristics and functional design requirements as well as case studies of selected inlets on the U.S. coasts.

2 UNCLASSIFIED

SECURITY CLASSIFICATION OF THIS

FOREWORD

This results from work done under Contract No. DACW72-74-C- 0005 between the author and the Coastal Research Center (CERC). It is one of a series of from the of General Invest ion of elidal Inlets (GITI) > which is under the tech- nical surveillance of CERC and is conducted CERC, the U.S.

Station ) other Government

The retired, coastal

Escoffier ic as a consultant in

firms and the of

Dr. R.r1. Sorensen, Chief, Coastal Structures Branch, was the con- tract monitor for the , under the s ion of R.P.

, Chief, Research Division.

Technical Directors of CERC and WES were T. Saville, Jr. and F.R. Brown, lye

Comments on this publication are invited.

lication in accordance with Public Law 166th, 79th 31 1945, as supplemented Public Law 172,

7 November 1963.

Colonel, of Commander and Director Commander and Director Waterways Station Coastal Research Center

:3

PREFACE

1. The of its Ci vii Works program sponsored, over the pas years, researcn into the behavior ar- acteristics of tidal inlets. The ' interest in ti let research stems its responsib es for navi on, beach erosion and control, and d Tasked wi the creation and of Ie U. S. w mil ions of

of material each year from tidal inlets that conne the ocean with bays, estuaries, and lagoons. Design and construction

exis tidal inlets are an ffices. In some red. Devel

c ris cs of inlets is tion and inlet stabili

s of storm surges role in the of

but 0 because and egress of flood bays and lagoons.

2. A research (GITl) was deve

the General Inves of Tidal Inlets tative data for ~se in design

of inlets and inlet i ectives:

It is des to meet the fol

the effects of wave action tidal inlet s tabili and

characteristics necessary to design e

new inlets, and and inlets; to evaluate il of tidal inlets; and

inlet tabili

The GITl is divided classification, ) inl

fication s ics

exist among c

s inlet

mental factors that control these characteristics. keeps the related

an in in characteristics of inlets.

b. The object are to define tide- flow

tions in the vicinity of coastal inlets and to cleve these TIle inlet ics s is

( let

three areas: (1) idealized inlet model s evaluation of state- of-the-art physical and numerical models. and ( inlet hydrauli cs.

4

"

The Idealized Inlet Mode 1 the effect

tructures on discharge, head loss and ve b of realistic inlet tide

ests zoidal inlet was conducted order that subs inlet models

number of

on on

( Eval The ectives f this mine the usefulness and model in

ay sys ems, determine whether economical are us in the

Inlet would be used along

exi techniques.

to deter-

and b c data was co at Masonboro Inlet f ical mode w initiated in 1969

have been sin then. In additi three exis numerical models were applied to ct the inlet I cs • Extensive field data were collected Inlet in 74 for e evaluat-

the c cal numerical models.

of relationsh

on thes

c. In s s to invest

wave action tion, channe into four bed mode and

and ne spe

The basic the interactions

at tidal lets as

( studies o

materials is of

tides, draul mor-

( Model Materials Evaluation. This evaluation was initi- ated in 1969 to de data on the response of movable-bed mode mate- rials to waves and flow to allow se on of the b materials for inlet models.

Movab le- Bed study is to evaluate the state-of-the-art of , in this case movable-bed inlet model Since, in many cases movable-bed mode is the on tool available for the response of an inlet to , the i li ties and limi tations of these mode Is must be established.

5

( a report entitled, of an Uncontrol Inlet Beach Erosion Board b to aid

Pro of inlets are and a al on

are studies to define the the respons f inlet navi

Field and office studies 0 the e

of natural sand channels to

ance at inlets. natural , and the effects of inlets on acent beaches.

is

4 is published in the GITI report series becaus it presents summary plus additional insi on some of the more tant works on tidal inlet and tabili It utes to the inlet parts (3b. of the GITL

6

CONTENTS

CONVERSION FACTORS. U.S. CUSTOMARY TO METRIC

SYMBOLS AND DEFINITIONS

I INTRODUCTION. .

II CHARACTERISTICS OF NATURAL INLETS

III INLET HYDRAULICS.

IV INLET STABILITY • •

V FUNCTIONAL DESIGN REQUIREMENTS.

VI CASE STUDIES ......... . 1. Masonboro Inlet, North Carolina 2. Rollover Fish Pass, Texas .. 3. Mission Inlet, California

LITERATURE CITED. . .

APPENDIX SUGGESTIONS FOR INLET DESIGN.

TABLES

) 9

10

15

15

19

41

53

S5 57 S9 63

66

71

1 Values of ~ and ........... 20

2 Resistance coefficient as on bed form for flume • .• 23

3 Coefficient C in tidal prism formula and ratio bay to ocean tidal range. · . . 31

4 Value of band N for the O'Brien 31, 1966) equilibrium formula t, 1976) .... · .. 42

S Tidal amp1i phase lags. and maximum head di at Gal ves ton Bay, Texas . . . . . . . . . . . . . . . 62

FIGURES 1 barrier beach tidal inlet. 17

2 Offset classification of an inlet. 18

3 of quadratic and linear formulas. 26

4 Surface level fluctuations of sea and basin. 30

7

FI -Continued

5 Sin T C versus the coeffi of etion ....

6 from Brown (192 and Keu1egan ( versus the coefficient of repletion .

7 \! from Brown 6 versus the coe

8 Ph as from Brown coefficient of

9 Schematic inlet and narrow uniform

10 Tidal m-inlet area

and (196 versus the

b wi th

11 des of inte limi ts and and

1

13

and \! versus

and various values of \! coeffic ent K"

coefficien , K

versus repletion

14 Definition for the stability number, A.

15 Nons channels, southern California

16 Masonboro Inlet, North Carolina ...

17 Area map show location of Rollover Fish Pass, Texas.

18 Rollover Fish Pass, Texas, 1970.

19 Mission Inlet, Cali fornia

8

36

43

46

48

48

o

56

8

o

61

64

cubic

acres

ounces