Cross-shore sediment transport on a naturally barred beach
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Authors
Humiston, Randall T.
Subjects
Sediment transport
DELILAH
Cross-shore transport
DELILAH
Cross-shore transport
Advisors
Thornton, Edward B.
Date of Issue
1993-03
Date
Publisher
Monterey, California. Naval Postgraduate School
Language
en_US
Abstract
Bailard's sediment transport model (1981) is evaluated using field data obtained on a naturally barred beach. Principal field measurements consist of a cross-shore array of bi-directional current meters spanning the surf zone and daily bathymetic surveys. The model predicts bed and suspended Load transport separately based on various velocity moments. The velocities are partitioned into mean currents, long waves (< 0.05 Hz) and short waves (.0.05 Hz) to determine their relative importance to the transport. Velocity moments are computed over 90 minutes intervals to resolve tidal fluctuations. Finally, predicted transport rates are integrated and compared with daily cross-shore bathymetric profiles (Averaged over a 400m length of beach). Results indicate the suspended load was consistently greater than bed load as much as an order of magnitude during episodes of large incident waves, owing to the slow fall velocity (2cm/s) of the fine grain sand within the surf zone. The contribution by the mean current, long and short waves to the cross-shore transport were of the same order. Variance of transport during all stages of tide and over a range of incident waves were consistently greater in the vicinity of the bar and trough than seaward of the bar and on the beach face. Tidal signatures were apparent in all modes of transport. The model appeared to under-predict measured bathymetry during low-energy periods and over-predict during high-energy conditions. However, the model does correctly predict the first order of movement of the bar
Type
Thesis
Description
Series/Report No
Department
Physical Oceanography
Meteorology
Organization
Naval Postgraduate School
Identifiers
NPS Report Number
Sponsors
Funder
Format
36 p.
Citation
Distribution Statement
Approved for public release; distribution is unlimited.