Considerations in Marine Sand Mining and Beach Nourishment

摘要

Beach nourishment restores beaches and enhances both their recreational value and their utility in shore protection. Increasing population in coastal areas and competition for land use has reduced the availability of terrestrial borrow pits while older sand pits have been exhausted. This situation has driven the search for borrow or mining sites offshore. Presently, almost all the marine sand mining along the Atlantic and Gulf coasts of the U.S. is to obtain material for publicly funded, beach nourishment. Much of this activity is in waters subject to federal jurisdiction. The demand for construction aggregate in metropolitan and developing coastal areas suggests that there might be an additional demand on offshore sand resources. Marine sand mining, as any type of dredging, disrupts habitat and can disturb transitory fishes and marine mammals. By altering the configuration of the sea floor, sand mining modifies wave transformation and, possibly, nearshore currents. Removing a large quantity of offshore sand and placing it in the nearshore zone alters habitat and sediment-transport processes. For over a decade, there has been a series of studies concerned with the potential environmental consequences of offshore sand mining and subsequent beach nourishment. A more recent set of projects developed and tested a suite of protocols for monitoring dredged and nourished areas. The field study testing the draft monitoring protocol was conducted in the active, sand-mining region of Sandbridge Shoal, offshore of Virginia Beach, Virginia.