(h) open-water disposal areas (submerged or above water) ; 



(i) hurricane or tsunami surge protection; 



(j) bridge and tunnel crossings; 



(k) shore erosion control (qualitative) ; 



(1) discharges o£ wastes (municipal, industrial, and 

 thermal) ; 



(m) freshwater supply (municipal, industrial, and 

 agricultural) ; 



(n) salinity control structures; and 



(o) i^stream control or diversion of freshwater inflow. 



In addition to investigations of proposed projects, the models are often 

 used to define existing prototype conditions for various situations where 

 no field data are available, to provide data with which other models 

 (physical or mathematical) are adjusted and verified, and to provide 

 boundary conditions required in the operation of other models. 



Studies of navigation channels are usually conducted to determine 

 ways to minimize maintenance dredging requirements or to determine main- 

 tenance requirements for a new or modified project. The effects of the 

 new or modified project on such environmental factors as tides, currents, 

 salinities, and dispersion must be determined; also it must be determined 

 that velocities and current patterns are not hazardous to navigation. 

 Studies of other navigation-related projects (manmade inlets and canals, 

 training works, sediment traps and turning basins, and port facility 

 siting) are usually concerned with essentially the same types of problems. 

 Qualitative studies of the potential for bank erosion are made during 

 investigations of new inlets, canals, or training works by defining the 

 current velocities and patterns adjacent to the shoreline. 



Landfill studies usually include determination of the effects on dis- 

 persion patterns, tides, currents, and salinities. If the fill is located 

 near an existing navigation channel, its effect on channel shoaling is 

 also determined. Studies of submerged open-water disposal areas usually 

 concentrate on the dispersal of sediments from the disposal area (i.e., 

 where the sediments redeposit) . For submerged disposal-bank or disposal- 

 island projects, studies will also determine their effects on current and 

 circulation patterns, dispersion patterns, tides, and salinities. Studies 

 of hurricane and tsunami barriers are concerned not only with ensuring 

 that the desired degree of flood protection is provided, but also with 

 developing the number and location of tidal passages required in the 

 barriers to preserve existing tidal, hydraulic, salinity, and dispersion 

 regimens under normal (nonsurge) conditions. 



