large, steep waves. These waves carry large quantities of sand from the 

 beach to the nearshore bottom. Land structures, inadequately protected 

 and located too close to the water, are then subjected to the forces of 

 waves and may be damaged or destroyed. Low- lying areas next to the ocean, 

 lagoons, and bays are often flooded by storm surge. Storm surges are 

 especially damaging if they occur concurrently with astronomical high tide. 



Beach berms are built naturally by waves to about the highest eleva- 

 tion reached by normal storm waves. Berms tend to absorb the wave energy; 

 however, overtopping permits waves to reach the dunes or bluffs in back of 

 the beach and damage unprotected upland features. 



When storm waves erode the berm and carry the sand offshore, the pro- 

 tective value of the berm is reduced and large waves can overtop the beach. 

 The width of the berm at the time of a storm is thus an important factor 

 in the amount of upland damage a storm can inflict. 



Notwithstanding changes in the beach that result from storm-wave 

 attack, a gently sloping beach of adequate width and height is the most 

 effective method known for dissipating wave energy. 



1.48 BEACH STABILITY 



Although a beach may be temporarily eroded by storm waves and later 

 partly or wholly restored by swells, and erosion and accretion patterns 

 may occur seasonally, the long-range condition of the beach - whether 

 eroding, stable or accreting - depends on the rates of supply and loss 

 of littoral material. The shore accretes or progrades when the rate of 

 supply exceeds the rate of loss. The shore is considered stable (even 

 though subject to storm and seasonal changes) when the long-term rates 

 of supply and loss are equal. 



1.5 EFFECTS OF MAN ON THE SHORE 



1.51 ENCROACHMENT ON THE SEA 



During the early days of the United States, natural beach processes 

 continued to mold the shore as in ages past. As the country developed, 

 activity in the shore area was confined principally to harbor areas. 

 Between harbor areas, development along the shore progressed slowly as 

 small, isolated, fishing villages. As the national economy grew, im- 

 provements in transportation brought more people to the beaches. Gradu- 

 ally, extensive housing, commercial, recreational and resort developments 

 replaced fishing villages as the predominant coastal manmade features. 

 Examples of this development are Atlantic City and Miami Beach. 



Numerous factors control the growth of development at beach areas, 

 but undoubtedly the beach environment is the development's basic asset. 

 The desire of visitors, residents, and industries to find accommodations 

 as close to the ocean as possible has resulted in man's encroachment on 

 the sea. 



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