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Asbury H. Sallenger

Publications and source records attributed to Asbury H. Sallenger.

23 records · Page 2Linked to original sources
USGS1989

Erosion and deterioration of the Isles Dernieres Barrier Island Arc, Louisiana, U.S.A.: 1853 to 1988

Using cartographic and aerial photography data from the years 1853, 1890, 1934, 1956, 1978, 1984, and 1988, shoreline change maps of the Isles Dernieres barrier island arc were constructed. These data were accurately superimposed, using a computer mapping system, which removed projection, datum, scale, and other cartographic inconsistencies. Linear, areal, and perimeter measurements indicate that the Isles Dernieres are suffering rapid rates of coastal erosion, land loss, and breakup. Bayside and gulfside erosion, in combination with sediment shortage and subsidence, have caused the Isles Dernieres to narrow through time. In addition, the core of the barrier island arc does not migrate landward and instead, breaks up in place as a result of inlet breaching and development. This is in contrast to other models of landward barrier island migration during transgression. If these trends continue, the Isles Dernieres will likely evolve into a subaqueous inner-shelf shoal by the early 21st century. Loss of the Isles Dernieres barrier island arc will severely impact the Terrebonne parish estuary, resulting in decreased environmental quality and increased public risk from storms and hurricanes.

Louisiana↗
USGS1984

High-frequency sediment-level oscillations in the swash zone

Sediment-level oscillations with heights of about 6 cm and shore-normal lengths of order 10 m have been measured in the swash zone of a high-energy, coarse-sand beach. Crests of oscillations were shore parallel and continuous alongshore. The oscillations were of such low steepness (height-to-length ratio approximately 0.006) that they were difficult to detect visually. The period of oscillation ranged between 6 and 15 min and decreased landward across the swash zone. The sediment-level oscillations were progressive landward with an average migration rate in the middle to upper swash zone of 0.8 m min-1. Migration was caused mostly by erosion on the seaward flank of the crest of an oscillation during a period of net seaward sediment transport. Thus, the observed migration was a form migration landward rather than a migration involving net landward sediment transport. The observed sediment-level oscillations were different than sand waves or other swash-zone bedforms previously described.

Marine Geology↗
USGS1983

A system for measuring bottom profile, waves and currents in the high-energy nearshore environment

A new data-acquisition system capable of measuring waves, currents and the nearshore profile in breaking waves as high as 5 m has been developed and successfully field-tested. Components of the mechanical system are a sled carrying a vertical mast, a double-drum winch placed landward of the beach, and a line that runs from one drum of the winch around three blocks, which are the corners of a right triangle, to the other drum of the winch. The sled is attached to the shore-normal side of the triangular line arrangement and is pulled offshore by one drum of the winch and onshore by the other. The profile is measured as the sled is towed along the shore-normal transect using an infrared rangefinder mounted landward of the winch and optical prisms mounted on top of the sled's mast. A pressure sensor and two-axis electromagnetic current meter are mounted on the frame of the sled. These data are encoded on the sled and telemetered to a receiving/recording station onshore. Preliminary results suggest that near-bottom offshore-flowing currents during periods of high-energy swell are important in forcing changes to the configuration of the nearshore profile.

Marine Geology↗