Coast is a geographical form consisting of sand, and located in the coastal marine area. Coastal areas into the boundary between land and ocean waters. The length of this coastline is measured surrounding the entire beach that is the territory of a country.
Indonesia is the second longest coastal country in the world after Canada. Indonesian coastline length was recorded at 81,000 km.
The coastline is a border meeting between the sea and the mainland in the event of highest tides. Sea line could change because of the abrasion, which hit coastal erosion by sea waves which cause a reduction in land area.
There are several important steps that can be done in securing the coastline such as breakwaters and development of vegetation on the beach.
To overcome the abrasion / grinding coastline from waves / waves can be used breakwater which serves to reflect wave energy back. Various ways are taken to solve them by using a stack wave made of concrete tetrapods at a certain distance from the coastline.
Mangrove forests can help to overcome the wave and simultaneously beneficial to animal life as well as breeding grounds of certain fish. Mangrove forests in most of North coast is gone because of human activities, which in turn will erode the beach.
Coral reefs are also a natural breakwater, making it necessary to be preserved and developed in defending the coastline.