282 mason. SHORE-CONTROL PROBLEMS [Ch. 15 



of small-scale, short-term shore processes that the need for assistance 

 from geologists is most important. 



The economic importance of shore control is largely a function of the 

 development and use of the specific shore area considered. At Atlantic 

 City, New Jersey, the shore-front property has a value of about 

 $200,000,000, and this value is dependent in major part on the main- 

 tenance in satisfactory condition of some 10,000 feet of shore. Judged 

 by this standard, each front foot of beach at that locality has a worth 

 of $20,000. Other resort areas have similarly fantastic worth at- 

 taching to their limited sea boundary. 



The value of beaches is strikingly illustrated by examination of the 

 expenditures made to maintain or retain them. The State of New 

 Jersey has spent $1,000,000 annually for 20 years in protecting its 

 beaches. Harrison County, Mississippi, is spending federal and state 

 funds in excess of $2,000,000 to repair a sea wall and provide beaches 

 for the cities of Biloxi, Gulfport, and Pass Christian. 



It is in navigation-shore-control problems that the economic signi- 

 ficance of shore control is most striking. The annual reports of the 

 Chief of Engineers, U. S. Army, covering the major portion of such 

 problems, show that each year the federal government alone spends 

 $48,000,000 to remove about 185,000,000 cubic yards of sediment de- 

 posited in navigation channels. In addition, millions of dollars damage 

 to downcoast shores is caused by the trapping of these unwanted de- 

 posits and their resulting loss from the littoral supply. 



It is difficult to assess the total economic significance of shore con- 

 trol to the people of the United States. Perhaps a conservative guess 

 might be of the order of $100,000,000 annually, considering only actual 

 expenditures and damage costs, and disregarding the intangible and 

 difficult to evaluate costs associated with loss of recreational benefits 

 and loss of shore area without immediate resulting damage. 



FACTORS INFLUENCING THE PROBLEM 



Two concepts are fundamental to the study of shore phenomena. 

 The first is that of the physiographic unit. This unit may be defined as 

 a shore area so limited that the shore phenomena within the area are 

 not affected by the physical conditions in adjacent areas. Analysis 

 of shore problems indicates that, for the purposes of studies directed 

 toward protection or modification of the shore, all important phenom- 

 ena depend on the material and energy available to the shore. What 

 we seek in a physiographic unit, therefore, is a shore area so defined 

 that the energy and material available within the area are not de- 



