Open AccessESTIMATES OP GROSS-SHORE BEDLOAD AND BED CHANGES
Author(s) -
Zbigniew Pruszak,
Ryszard B. Zeidler
Publication year - 1988
Publication title -
proceedings of conference on coastal engineering/proceedings of ... conference on coastal engineering
Language(s) - English
Resource type - Journals
eISSN - 2156-1028
pISSN - 0589-087X
DOI - 10.9753/icce.v21.131
Subject(s) - shore , bed load , flume , geology , wave flume , sediment transport , tracer , sediment , hydrology (agriculture) , geomorphology , geotechnical engineering , flow (mathematics) , oceanography , mechanics , breaking wave , wave propagation , physics , quantum mechanics , nuclear physics
Four series of tracer studies employing radioisotopic sand, tracked remotely from land, were carried out at the IBW PAN's coastal research station at Lubiatowo. Incipient motion of single grains with velocity Vcr1 has agreed with Komar and Miller's (1974) formula, and has been 5...8 times smaller than voro, the threshold velocity of water inducing bulk motion_of sediment. The ratio of average nearbed water velocity, v, to_the effective speed of tracer sand, in the inshore zone, va, is estimated about 100...1,000. The cross-shore sediment transport rates measured are ten times smaller than those predicted by Pruszak's (1987) energetics formula, the discrepancy being due to the real field phenomena of mixing and overburdening in a thick bed layer. Our wave flume and wave tank studies with movable bed point to the importance of initial slope in shore evolution. The laboratory findings on bed variability are extended by our 1987 field data obtained with an ultrasonic setup. Intensive cyclic depth changes are acoorapanied by varying transport rates computed from continuity equation.