Resuspending of the sediment particles from the bottom is a process generated by different causes.
One of them are waves, which can be generated by wind, tectonic activity, moon and sun attraction,
different moving objects in the sea and other causes. In this work we discussed the effect of wind
generated waves on the bottom shear stress (the tension created at the contact of the sediment and the
moving water). To calculate the shear stress wave heights and wave periods are needed throughout the
surface and in every time step. These parameters can be obtained with observations, measurements or
with the help of mathematical models. Simplified wave height and period equations (Bretschneider,
1952) are already a part of the sedimentation module of the PCFLOW3D model; however, the results
obtained are questionable. In order to find a better method we made a short review of seven different
empirical methods for calculation of the significant wave height and period. Using the MS Excel we
tested these methods on different input data (wind speed, fetch length and water depth) and compared
the results with each other and with the Darbyshire and Draper nomograms (Koutitas, 1988). The
results obtained by all tested methods are approximately for one third lower than the results obtained
using Bretschneider’s method. Therefore the equations in the PCFLOW3D model need to be replaced.
As the results of the tested methods do not differ significantly, additional research is needed: a
comparison with the results of the third generation wave model (SWAN) and with measurements at
the buoy Vida operated by the National institute of biology.
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