However, the tests indicated that the amount of scour depends quite crit- 
ically on wave height, and that the direction of movement of the scour 
material depends primarily on sand size (being greater offshore with finer 
sands) and wave period (being greater offshore with shorter periods). 
(1) Wave Transmission Over Low-Crested Breakwaters, 
A study was made for the Navy Bureau of Yards and Docks of wave trans- 
mission over certain proposed low-crested breakwaters which would permit 
considerable overtopping of storm waves. Tests involved only rubble-mound 
breakwaters, but both permeable and impermeable breakwaters were tested, 
thus affording a comparison of the amount of energy transmitted through 
the breakwater as opposed to that transmitted over the crest of the break- 
water, A report discussing the tests for the Navy is under preparation, 
and it is hoped that it can be published in 1964. It is planned to follow 
these tests with additional small scale tests on submerged breakwaters of 
both rubble and vertical pile types. 
A small test of similar type was also carried out for the Galveston 
District of the Corps of Engineers and is reported in an article, "Model 
Study of Offshore Wave Tripper" by F. F. Monroe. 
(m) Beach Vulnerability as Related to Storm Wave and Water Level 
Conditions, 
Following Congressional discussion of the March 1962 Atlantic storm 
investigations have been initiated by various Government agencies on the 
improvement of storm warning data. Responsibility for issuance of storm 
Warnings is that of the Weather Bureau, but the Weather Bureau and the 
Corps of Engineers have initiated a study to provide data on the vulner- 
ability of shore areas for particular storm waves and tides which might 
occur from a particular storm. It is recognized that the Weather Bureau 
may be able to forecast relatively accurately the water levels and waves 
which may occur from a particular storm, but the damage which may result 
from these water levels and waves will then depend primarily on the con- 
dition of the elevation and width of the beach area on which it impinges. 
The beach condition, and hence the shore vulnerability, is different for 
different locations and also varies from time to time at any given 
location. Study has now been initiated on several beaches in the New 
Jersey, New York, and New England area in an attempt to relate observed 
beach changes and/or damage to observed water level and wave conditions, 
with the aim of accumulating data which may be used to prepare vulner- 
ability charts for different types of beaches in other areas. 
? 
(n) Interlocking Precast Concrete Block Seawall Study. 
A study is being made of various types of interlocking precast con- 
crete blocks for use as seawall protection: It is felt that such type 
walls might afford relatively inexpensive backshore protection for severe 
storms, although they may not be expected to substitute for normal pro- 
tection in the immediate normal wave action zone. Field installations 
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