By-passing and backpassing with special reference to conditions in Florida

Abstract

By-passing by natural action is mentioned with special reference to Florida Inlets and to some other inlets in the United States and abroad. Natural by-passing at harbors on open shores is dealt with briefly. Present status of by-passing plant operations in Florida is reviewed. Inasmuch as it is evident that by-passing plants - partly because of the tidal flow which discharges material in the ocean and in the bay and partly as a result of the rise of sea level - will not be able to solve more than a certain part of a beach erosion problem--replenishment by sand from other sources is indispensable. The most logical source is offshore deposits. Material may be brought to shore by "backpassing" using an offshore scraper (useful for maintenance) or by a special hydraulic dredge (for major improvements). If the borrow area is located close to shore, the question arises of whether the borrow pit will fill up again by material from further offshore material from the sides or from material dragged out by waves from the beach. The report describes briefly tests on Jupiter Island using an offshore scraper. The success of this operation is checked by fluorescent tracers placed on the beach and on all sides of the borrow pit.