OCEANOGRAPHY IN THE UNITED STATES 33 



Mr. Caldwell. Apparently so. The oxygen apparently acts more 

 rapidlv" with the steel when it is warm than when it is cold. It shows 

 that we broke this tiling down into different areas southern and 

 northern and different types of exposure and we arrived at a corrosion 

 figure in terms of thousands of an inch per year so we can compute the 

 life of these structures. 



This next slide shows the usefulness of some of our wave generation 

 formulas and methods we have worked up. We had occasion to 

 develop the wave conditions on Lake Michigan and Lake Erie and 

 Lake Ontario in connection with our erosion control studies, and these 

 locations show where we took a set of weather maps for a period of 

 3 years and hindcasted the waves. We took the maps and predicted 

 what the waves were at these locations for this 3-3^ear period and used 

 this as a statistical basis for the wave climate of these particular loca- 

 tions. We have them scattered all around these lakes. We will 

 ultimately do Lake Superior and Lake Huron but the pressure was 

 on us for these three locations at the time. 



If we want to get a location near St. Joseph, Mich., we would 

 interpolate between Chicago and Muskegon so that we can work out 

 our problems on that basis. 



Tliis is the last slide. W"e decided to find the relative effectiveness 

 of various types of seawalls in prevention of overtopping during wave 

 action so we built about every type of seawall in one of our wave 

 tanks and defined their relative effectiveness against wave runup. 



This shows the relative height at which the various structures 

 would have to be built to have the same effect in restraining or pre- 

 venting the overtopping from wave action. You find that the most 

 ineffective is one with the gradually sloping face that comes up vertical 

 at the tangent. If we take the same wall and put a kickback right 

 on top of it, we can cut it to about half its height and have the same 

 overall effectiveness. 



We were very interested in working out these different shapes and 

 we think that the field now has a little more guidance instead of un- 

 proved notions that were kicking around as to which has the most 

 effectiveness. 



I have one or two other remarks. What I wanted to say in closing 

 here was that I believe you will sense that the research activities of 

 the Beach Erosion Board cover quite a variety of subjects although 

 they are all leading to the same end product. 



We realize that our fi.ndings are valuable in other fields of activity, 

 such as in navigation through our inlets. The Corps of Engineers has 

 this problem of maintaining navigable inlets and much of our findings 

 on the shore processes is of some value to them. 



Also, in this hurricane business, this amount of flooding that can be 

 expected from a hurricane, we come at that in our studies of wave 

 action. 



As a result of our research studies coupled with other available 

 information, the Beach Erosion Board has prepared and published a 

 technical report which is the doctrine of the Beach Erosion Board as 

 regards shore control or prevention or protection of the shore. 



This is a looseleaf document with the body of itself plus its appen- 

 dices. It has about 400 pages. It has become the handbook for 

 shore protection planning and design not only in this country but 

 pretty much overseas. We have been requested and have granted 



