THE ECONOMICAL HEIGHTS OP SEA WALLS FOR COAST PROTECTION IN JAPAN

Abstract

The purpose to construct coast protection works is to protect properties and human lives front the disasters of storm tides, cruel waves, beach erosions, and others. We may expect that the stronger the works are built, the more the disasters will be prevented, but it cost more to strengthen them. Prom a view point of national economy, both the construction cost and the amount of damages are regarded as the losses. In general, the amount of damages will be enormous if no protection work is constructed, but the construction cost of protection works to reduce the damages infinitely small will also be enormous. The loss in national economy, or the sum of the damages and the construction cost, will be minimized on some suitable magnitudes of protection works. We deviced a concrete calculation method to decide economical magnitudes of coast protection works, and have applied the method to practical plannings. The paper discusses the fundamental idea of the method and the results of the application.