Along the East Dam of High Island Reservoir, there are many groynes facing the sea. The groynes are made by more than 2500 huge T-dollos and they are permeable to let sea water pass through. When there is strong wave, the T-dollos can break up, absorb and reflect the energy of the waves and thus the waves will be released. Therefore, the wave velocity and energy are reduced to prevent the sea water from reaching the dam and protect the reservoir.
Secondly, there are many ditches and holes. If the waves are strong enough to pass through T-dollos, the ditches will drain the sea water away to protect the east main cofferdam from erosion and damage.
Moreover, there is a buffer dam which act as a buffer zone. When the wave are very strong that the T-dollos cannot prevent the water going into the dam and the ditches and the holes cannot drain the sea water away, the buffer dam is to trap the water in order to protect the east main cofferdam from damaging.
If there are no these coastal management such as T-dollos, ditches and buffer dam, the