IZH = H«10 5 + Z«10 (42) 



If the length unit is meters, H must be given to the nearest centimeter (in 

 the format F4.2), whereas if the length unit is feet, H must be given to the 

 nearest tenth of a foot (format F4.1). 



308. The integer IZH will be converted to real numbers by GENESIS. 

 If the wave direction is negative, IZH should be given a negative sign. 

 Example 1 : If ICONV = 1 (metric units selected at Line A. 2 in the START 

 file), H = 2.18 m and Z = 10.7 deg will produce the value IZH = 218107 . 

 Example 2 : If ICONV = 1 , H = 1 . 14 m and Z = -6.5 deg will produce the 

 value IZH = -114065 . 



Example 3 : If ICONV = 2 (American customary units selected), H - 10.1 ft 

 and Z = 21.0 deg will produce the value IZH = 101210 . 



309. It can be seen that the largest nearshore wave height that can be 

 entered depends on the units selected and is either 9.99 m or 99.9 ft, and the 

 largest magnitude of the wave angle is 99.9 deg. (If the wave refraction and 

 shoreline grids are parallel to each other, a wave approaching normal to the 

 shoreline will have an angle of deg; therefore, the practical maximum 

 magnitude of the wave angle is 89.9 deg. Usually, wave angles will have much 

 smaller magnitudes.) 



310. In summary, wave heights can be expressed to the nearest centi- 

 meter if metric units are used or to the nearest tenth of a foot if American 

 customary units are used. Wave direction can be specified to the nearest 

 tenth of a degree. The construction of WAVES files with data from an external 

 wave calculation is given in the GENESIS Workbook. 



311. NWD = . If NWD = was entered in the START file, simple wave 

 refraction and shoaling algorithms contained in GENESIS will be used to bring 

 waves from the offshore depth specified at Line B.2 to breaking points along- 

 shore. This procedure will treat the local bottom contour as being straight 

 and parallel to the calculated offshore contour (see Part V). In this case, 

 for each time step, WAVES contains only the offshore wave period, height, and 

 direction in the format described above for the case of NWD = 1 . Examples 

 of WAVES files with and without nearshore waves with only one wave component 



128 



