ABSTRACT

Louisiana has the highest rates of coastal erosion and land loss in the United States. Rates of coastal land loss exceed 50 mi²/yr. Louisiana's barrier islands are rapidly decreasing in area and eroding at rates up to 65 ft/yr. Between 1880 and 1978, Louisiana's barrier islands decreased in area by 41 percent, shrinking from 37 mi² to 22 mi². The life expectancy of individual barrier island systems ranges between 30 years for the Isles Dernieres and 225 years for the Chandeleur Islands. Preservation and restoration of our barrier island environments requires a dynamic landscape maintenance program of regularly scheduled beach nourishment, barrier restoration, shoreface nourishment and revegetation projects. Such projects require viable sources of suitable sand for construction. High resolution seismic profiles were collected in the study area during cruises from 1982 through 1986. Approximately 7500 line kilometers of profiles, both 3.5 kHz and ORE Geopulse data, were collected for this paper. Vibracores were obtained in 1983 and in 1986. A total of 152 vibracores were used in conjunction with the seismic reflection profiles to define 55 nearshore sand resource targets in the area between Marsh Island and Sandy Point. The sand resources include distributary channel, inner shelf shoal, recurved spit, tidal delta, tidal channel, submerged beach ridge, and barrier shoreface deposits. The targets range in area from about 2 km² to greater than 400 km², with estimated volumes of available sand varying from less than 2,000,000 m³ to greater than 1,600,000,000 m³.