131 



g:ift. In all cases a large investment is required to support and sustain 

 this activity. Adequate channels must be provided to carry the ship 

 traffic. In almost all estuaries this involves maintenance dredging to 

 provide sufficient water depth to float deep draft vessels (fig. IV.2.15). 

 These channels must be marked with navigation aids to prevent the 

 ships from inadvertently straying into shallow water. Terminal facili- 

 ties are necessary for loading, unloading, and storing cargo. There 

 must also be shipyards with all the equipment and facilities necessary 

 to repair, maintain, and fuel the large ships (fig. IV.2.16) . 



Besides the physical facilities needed, there are certain environ- 

 mental considerations. Already mentioned is sufficient water depth 

 to keep the ships afloat. Since dock facilities and berthing space are 

 expensive and cannot be monopolized for long periods of time by 

 single ships, there must be safe anchorage areas where ships can await 

 their turn at the piers. These anchorage areas also provide temporary 

 safety during stormy weather and must, therefore, be sheltered from 

 the direct force of the wind and waves. The whole concept of a harbor 

 is a port of safety out of harm's way. 



The advent of nuclear powered ships has presented additional prob- 

 lems. The harbor areas must be protected from every possibility of 

 environmental contamination by radioactive substances, and these 

 ships must have easy access to the sea. 



The use of the harbors for waterborne transportation is competi- 

 tive in that it may cause other uses to be foregone. Heavy ship traffic 

 interferes with pleasure boating and related activities (fig. IV.2.17). 

 Maintenance of the ship channels may alter the ecology and the surface 

 area occupied by the large vessels may well interfere with safe pleasure 

 boating. 



Transportation in estuaries is not limited to waterborne traffic. 

 Since a major percentage of large cities are located on estuarine sys- 

 tems, there is considerable pressure to develop fill areas for airports 

 which then utilize the long overwater approaches to keep the jet noise 

 away from developed areas. San Francisco International Airport is 

 a good example, and in Washington, D.C., National Airport uses fill 

 areas and overwater approaches (fig. IV.2.18) . 



As the airplanes get bigger and the air traffic gets heavier, it ap- 

 pears that more cities will try to develop isolated airport facilities. 

 The planning of the Miami Jetport in the Big Cypress Swamp is a 

 good example. In cities where estuarine areas are available a similar 

 trend will probably develop. The last aspect of transportation to be 

 considered is that of land transport. A dichotomy exists here. The 

 water areas offer a barrier to land travel that must be overcome with 

 causeways or bridge type structures which can interfere with naviga- 

 tion or cause habitat damage. On the other hand, peripheral roads 

 offer some of the more scenic routes available and are frequently the 

 only undeveloped area on which roads can be built. Examples of 

 these peripheral roads are Bayshore Drive in Tampa, Fla. ; Bayshore 

 Freeway south of San Francisco; and Harbor Drive in San Diego 

 (fig. IV.2.19). 



SECTioisr 4. Use as a Human Habitat 



These are the uses that occur wherever people live and work in civi- 

 lized communities. They represent uses not unique to coastal areas, 

 although the estuarine zone places restrictions on some uses and offers 

 advantages in other activities. 



