Accession Number : ADA182435

Title :   Short-Term Impoundment of Longshore Sediment Transport.

Descriptive Note : Final rept.,

Corporate Author : FLORIDA UNIV GAINESVILLE DEPT OF COASTAL AND OCEANOGRAPHIC ENGINEERING

Personal Author(s) : Bodge,Kevin R. ; Dean,Robert G.

Report Date : MAR 1987

Pagination or Media Count : 384

Abstract : The cross-shore distribution of longshore sediment transport is investigated through the distribution of sediment impounded against a shore-perpendicular barrier over short-term intervals in field and laboratory environments. For each field experiment, a low-profile groyne was deployed across a natural beach in less than 8 hr and profiles near the groyne were repeatedly surveyed for 8 to 20 hr thereafter. For each laboratory experiment, a low-profile barrier was installed across a pre-equilibrated fine sand model beach, and profile changes near the barrier were measured after 5 to 40 minutes of regular, obliquely incident, unidirectional wave action. Breaking wave angle and longshore current and wave height across the surf zone were also measured. The effects of crossshore transport and tidal fluctuation were addressed in the survey data, and the effectiveness of the barriers as impoundment agents is discussed. Local downdrift profile changes were found to be poor indicators of the local updrift impoundment. In general, the longshore transport profiles were found to be bimodal with peaks just landward of the breakpoint and near the shoreline. The relative significance of the longshore transport shifted from the near-breakpoint peak to the near-shoreline peak as the wave condition varied from spilling to collapsing breakers. Keywords: Beach erosion; Groins(Shore protection).

Descriptors :   *SEDIMENT TRANSPORT, ANGLES, BARRIERS, BEACH EROSION, FIELD TESTS, HEIGHT, INDICATORS, LABORATORY TESTS, LOW LEVEL, TRANSPORT, PROFILES, OCEAN WAVES, SEDIMENTS, SHORES, SHORT RANGE(TIME), STORAGE, SURF, SURVEYS, TIDES, TRANSPORT PROPERTIES, UNIDIRECTIONAL, VARIATIONS, WATERFRONT STRUCTURES, OCEAN CURRENTS, MODEL TESTS, BEACHES, SAND, FINE GRAINED MATERIALS, DISTRIBUTION

Subject Categories : Physical and Dynamic Oceanography

Distribution Statement : APPROVED FOR PUBLIC RELEASE