4.736 Deflation . The loose sand that forms beaches is available to be 

 transported by wind. After a storm, shells and other objects are often 

 found perched on pedestals of sand left standing after the wind eroded 

 less protected sand in the neighborhood. Such erosion over the total 

 beach surface can amount to significant quantities. Unstabilized dunes 

 may form and migrate landward, resulting in an important net loss to the 

 littoral zone. Examples include some dunes along the Oregon coast (Coo- 

 per, 1958), between Pismo Beach and Point Arguello, California (Bowen 

 and Inman, 1966); central Padre Island (Watson, 1971); and near Cape Hen- 

 lopen, Delaware (Kraft, 1971). Typical rates of transport due to wind 

 range from 1 to 10 cubic yards per year per foot of beach front where 

 wind transport is noticeable. (Cooper, 1958; Bowen and Inman, 1966; 

 Savage and Woodhouse, 1968; and Gage, 1970.) However average rates prob- 

 ably range from 1 to 3 cubic yards per year per foot. 



The largest wind-transported losses are usually associated with 

 accreting beaches that provide a broad area of loose sand over a period 

 of years. Sand migrating inland from Ten Mile River Beach in the vicin- 

 ity of Laguna Point, California, is shown in Figure 4-48. 



Study of aerial photographs and field reconnaissance can easily 

 establish whether or not important losses or gains from wind transport 

 occur in a study area. However, detailed studies are usually required 

 to establish the importance of wind transport in the sediment budget. 



4.737 Carbonate Loss . The abrasion resistance of carbonate materials 

 is much lower than quartz, and the solubility of carbonate materials is 

 usually much greater than quartz. However, there is insufficient evidence 

 to show that significant quantities of carbonate sands are lost from the 

 littoral zone in the time scale of engineering interest through either 

 abrasion or solution. 



4.738 Mining and Dredging . From ancient times, sand and gravel have 

 been mined along coasts. In some countries, for example Denmark and 

 England, mining has occasionally had undesirable effects on coastal settle- 

 ments in the vicinity. Sand mining in most places has been discouraged by 

 legislation and the rising cost of coastal land, but it still is locally 

 important. (Magoon, et al., 1972.) It is expected that mining will become 

 more important in the offshore area in the future. (Duane, 1968, and Fisher, 

 1969.) 



Such mining must be conducted far enough offshore so the mined pit 

 will not act as a sink for littoral materials, or refract waves adversely, 

 or substantially reduce the wave damping by bottom friction and percolation. 



Material is also lost to the littoral zone when dredged from naviga- 

 ble waters (channels and entrances) within the littoral zone, and the 

 dredged material is dumped in some area outside of the littoral zone. 

 These dump areas can be for land fill, or in deep water offshore. This 

 action has been a common practice, because the first costs for some 

 dredging operations are cheaper when done this way. 



4-129 



