but inovement i/as general at this velocity and above. Figure 55 shows 

 wind velocity gradients taken during typical runs. Figure 56 shows the 

 relation between wind velocity and rate of s and moveitent. The rate of 

 movement is in terms of the nuiaber of pounds per linear foot of beach 

 passing a given line in one day. 



SUMI4ARY OF FACTORS RELATED TC FUNCTIONAL PIAIMNIMG 



106. As a basis for the functional planning of coastal works to attain 

 a desired revsult, consideration of the foregoing factors will determine 



for each pertinent locality these significant facts in greater or less 

 detail: 



a. Direction and character of xjsves reaching loca] ity^ 



b. Storms, storm waves and their effects) 



c. Changes in vjater level; 



d. The rates of littoral drift to various depths offshore; 



e. Sources and losses of materials; 



f . Grain size of materials along profiles; 



g. Location of aggrading and eroding areas; 



h. Seasonal variations i-elated to above factors; 



i. Conclusions as to dominant characteristics of shore processes. 



107. Many of the above factors may be expressed in a table to show 

 relative importance at various points along the shore being studied. 



FUNGTIGNi^JL. PLANNII^G OF PROTECTIVE i^^iSASUfuES 



108. Introduction . - In vS electing the shape,, size, and location of 

 works the objective should be to design an engineering work which will 

 accomplish the d.esired result most economically and with the least damaging 

 effect on adjacent shore lines. The following paragraphs describe the most 

 coromon engineering solutions now used to meet functional requirements^ and 

 give guides for their application, 



SEAVJAILS, REVETMENTS MD BULKHEADS 



i09. Functions . - Bulkheads j, revetments, and seawalls are structures 

 placed parallel or nearly parallel to a shore line. They both separate 

 a land area from a water area, but differ functionally in the type of pro- 

 tection afforded. The primary purpose of a bulkhead is to retain or pre- 

 vent sliding of the land, with the secondary purpose of affording protection 

 to the fill against damage by wave action. The primery purpose of a 

 seawall or revetment is to protect the land and upland structures from 

 damage by wave forces, with incidental functions as a retaining wall or 

 bulkhead. Because of the similarity of the respective functions, the two 

 types of structures are entirely similar in design. For example, a 

 design for a bulkhead to resist high earth pressirres at one locality could 

 well be used for a seawall at another locale. However, for a given area, 

 a seawall necessarily would be of heavier construction than a bulkhead 



66 



