Equilibrium Beach profile measurement and sediment analysis : Mustang Island, Texas.

168 Pages·1.5 MB·en_US

by  Knezek, Erick B.

1UUL
DUDLEY KNOX LIBRARY
NAVAL POSTGRADUATE SCHOOL
C
MONTEREY >101

Equilibrium Beach Profile
Measurement and Sediment Analysis:
Mustang Island, Texas
Major Report
by
ENS Erick B. Knezek, CEC, USN
Submitted in partial fulfillment
ofthe requirements for the degree of
MASTER OF ENGINEERING
December 1997
Major Subject: Ocean Engineering

LEY KNOX LIBRARY
•OSTGRADUATE SCHOOL
MONTEREY CA 93943-5101
Abstract
This engineering report describes the measurement techniques and results ofan
A&M
equilibrium beach profile survey and sediment analysis conducted by Texas
University, Ocean Engineering Program, at Mustang Island, Texas on September 27,
1997. The main objective ofthe project was to obtain an accurate equilibrium beach
profile at a location on Mustang Island, and to compare the actual profile to a predicted
profile. The predicted profile is based on the median grain size diameter ofsediment
samples taken from the dune crest to approximately 4000 ft offshore.
The survey was accomplished using an electronic total station with a standard
surveying rod on land, and the underwater profile was measured with a "sled" towed
behind a boat. A triple prism was attached to both the top ofthe rod and sled. The sled
is an aluminum and steel structure equipped with two 12 ft long skids and a 36.5 ft mast.
The predicted profiles are based on two methods. One method uses Dean's
(1997) equation for equilibrium beach profiles, z = Ax 2/3 , where z is the water depth, A
is the profile scale factor related to the sediment fall velocity, and x is the distance
offshore. The other method involves a more complex analysis described by Dean and
Dalrymple (1996), which accounts for a variation in sediment size and profile scale
factor, A, in the offshore direction. Both methods are described and compared in this
report. This data will also be used by Dr. R. G. Dean ofthe University ofFlorida in a
study he is conducting on equilibrium beach profile prediction.
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Dedication
This report is dedicated to Jill, Amber, and Sammi for all oftheir love, patience,
and assistance.
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