wave calculation cells alongshore will be a multiple of the cell length used 

 by GENESIS. 



242. Line B . 6 : DTW In situations where the temporal resolution of 

 the available wave data is not as great as the time step DT to be used in 

 the simulation, it is possible to run GENESIS with repeated wave conditions at 

 each time step, as specified by the variable DTW . As an example, suppose 

 wave data are only available at 24-hr intervals, but the model is to be run at 

 the standard 6-hr time step to maintain numerical accuracy and/or stability; 

 then by specifying DTW = 24 on line B.6 (and DT - 6 on line A. 5), each set 

 of wave conditions in the WAVES file will be run four times. Repetition of 

 wave data is also used in the modeling of simple hypothetical cases in which 

 constant wave conditions may be acceptable throughout the entire simulation; 

 DTW can be set to be equal to or greater than the total simulation time in 

 hours determined by the values specified at Lines A. 5 through A. 7. Then the 

 first wave condition in the WAVES file will be run at every step. 



243. Line B.7: NWAVES The variable NWAVES provides the number of 

 independent wave sources per step. Wave measurements often show two or more 

 spectral peaks, indicating the presence of distinct wave trains. For example, 

 swell may arrive from a distant storm, whereas sea waves are generated by 

 local winds. These two types of waves are independent and will have different 

 heights, periods, and directions. Also, WIS provides sea and swell components 

 separately. GENESIS allows input of an arbitrary number of wave components. 

 These are treated independently, with each component generating a longshore 

 sand transport rate. The transport rates from each wave component at a given 

 time step are added linearly, including sign, to give the net transport rate 

 at that time step. 



244. As another situation in which an extra wave component might enter 

 a simulation, a long jetty may reflect a significant portion of the incident 

 wave energy. If reflected waves are believed to appear in the breaking wave 

 climate and influence shoreline evolution in the area, a time series of these 

 waves may be included as a component in the WAVES file . 



245. Line B.8: WDATS The starting date of the shoreline change 

 simulation was given at Line A. 6. From the date of the start of the wave file 

 WDATS entered at the present line, GENESIS determines the location in the 



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