THE EFFECT OF GRAIN SORTING ON PROFILE STABILITY OF NOURISHED BEACHES

Ram K. Mohan, Timothy W. Kana

Abstract


Dean's (1983) model is often used to predict the profile shape and berm width after nourishment. Ideally, if the borrow sediment is identical to native sediment, the adjusted profile will take on the same shape as the existing profile. But, if the borrow sediment is coarser than native, the nourished profile will adjust to a steeper configuration, producing a wider dry beach. If borrow sediments are finer, the fill will adjust to a gentler slope, producing a narrow dry beach. A conceptual model of the effect of grain sorting on nourished profile stability is presented in this paper and verified by comparison with actual beach measurements. The results indicate that the post-nourishment performance can be improved measurably by minor variations in grain size distribution, specifically where a coarse fraction is present (i.e., negative skewness). Fill placement technique and other environmental factors, of course, also impact performance.

Keywords


grain sorting; beach nourishment; beach stability

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