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Description:
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Erosion problems are not only in the Texas area , but exist also along the coastline
all over the world . Even though many researchers have studied coastal processes
related with beach erosion and deposition over the decades , these processes are too
complex to understand completely and field measurements are difficult to obtain
during landfall of storms which cause fatal damages .
Overwash is strongly suspected to cause extreme erosion as seen from long -term
field measurements in the upper Texas coast . Overwash and washover are the source of
cross -shore erosion and deposition of beach material along the coast , respectively .
Waves superimposed on increased storm surges overtop and generate serious erosion of
the berm . However , the data for these processes do not completely describe the
shoreline erosion problems . Providing better descriptions requires field measurements
and laboratory experiments with careful calibration .
This study was conducted in two major sections . First was a field measurement
and second was a laboratory experiment .
This study used the RTK -DGPS to measure the change in the beach profile over
multi year period . The GPS system is one of the ways to have the best resolution . The laboratory experiment was done in a 2D wave tank on mid -scale based on
similitude law at Texas A &M University . The experiment was necessary to obtain
better empirical formulas .
The erosion rate of the sand was measured at different wave conditions and slopes
of the berm or upper beach face in regular and irregular waves respectively . The
erosion rate is much bigger at higher wave height , longer wave period and steeper
beach face . The erosion rate is increased proportional to speed of bore and it is
decreased with time .
The empirical formulas were the first approach to simulate the impact of overwash .
The laboratory results represented good agreement with the field data and might be
applicable to predict the shoreline recession by overwash induced by storms . Further
improvements can be expected by adding these empirical formulas to a numerical
model to predict sediment transport in the swash zone . |