الفهرس 
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Abstract
The present study investigates the positive and negative effect of the protection works erected at
different sites on the northern Egyptian coasts .The study deals with the field and mathematical
solutions for the problem of the erosion at the various shores .It became clear that some available
mathematical models are not suitable for use unless modification and correction are carried on
the model depending on the local data and observation of the Egyptian coasts. The mathematical
models available were compared and discussed. The obtained results are compared with the
previous researches. Important results and conclusions are reached at for the concerning methods
of measurements and the mathematical models. The use of the radiotracer methods in sediment
transport and collecting the data is discussed and presented in the thesis. The results reached
shows the negative effect of some structures erected on the shore due to lake of data ,improper
design or the use of unsuitable mathematical models. The measurements of sea water depth,
bottom soil data, and sea currents should cover a range in the sea up to the closure depth. The
mathematical models should be suitable for the Egyptian shores. A flow chart suggestion for a
mathematical model to overcome the negative problems in using the available models is
presented. Bathymetrical maps were prepared according to the measured profiles and new
measured data for the waves, winds and currents are presented.
The problem of erosion of the northern Egyptian shores took the attention of many researchers.
So many studies had been carried out and many suggestions had been made .Measurements of
sea water depth, sediment characteristics, wind data ,currents data were carried out. According to
the previous studies and measurements several proposals were suggested and several designs
were made ,and many structures were erected ,like groins, breakwaters, seawalls and sand
nourishments.
The new approach is expected to eliminate the negative effect of any proposed protection
structure. The main conclusions are presented at the end of thesis .