ACCRETION OF BEACH SAND BEHIND A DETACHED BREAKWATER.
CORPS OF ENGINEERS WASHINGTON D C BEACH EROSION BOARD
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The problem of sand transport by a longshore current is clarified by observing the effect of a breakwater on this current. Sand samples were collected on a network from the beaches in the vicinity of the breakwater at Santa Monica, California. The distribution of median grain sizes is evidence for a reduction of the competence of the longshore current. The history of shore line changes discloses an accompanying reduction in the capacity of the current. A decrease in transporting power of the longshore current is correlated with a decrease in Q, the littoral drift factor, so that Q can probably be used as a qualitative measure of the sand transporting power of longshore currents. The history of accretion indicates that a shore line changes position in a direction toward equilibrium with respect to the forces acting on a beach. Given enough time, it is probable that the breakwater will become connected to the mainland.
- Physical and Dynamic Oceanography
- Civil Engineering