Ch. 15] 



SHORE-CONTROL PROBLEMS 



279 



vide palliative measures for such deleterious effects of the works as 

 may not be avoided. 



A third type problem of shore control is associated with harbor-pro- 

 tective works. These works take the form of breakwaters and jetties 

 extending seaward from the shore. Their function is to protect a given 

 water area against wave action, thus providing a shelter for craft. 



Fig. 3. Santa Barbara, California. Littoral material impounded by harbor 

 breakwater and passing into harbor. June 1938. (Photo by Beach Erosion 



Board.) 



Unfortunately the structures projecting from the shore act as barriers 

 to the natural movement of material alongshore. The offshore struc- 

 tures, or breakwaters, reduce or destroy wave action, thus eliminating 

 the principal force that causes material transportation. The problem 

 here is to prevent starvation of the downdrift shore, and in some cases 

 to control excessive accretion of material on the updrift side of the 

 harbor. Santa Barbara Harbor, California (Fig. 3) is an excellent 

 illustration of the problem. A dog-leg, or curved, breakwater was built 

 from shore into deep water to provide a sheltered anchorage for small 

 craft. Within a few years the entire updrift area of impoundment of 

 the jetty was filled to capacity, and littoral drift passed into the 



