Example Problem III-2-1 (Concluded)

Using Equation 2-7b with *K *= 0.23,

ρ* g*

16 κ1/2

(ρs & ρ) (1 & *n*)

(1025) (9.81)1/2

(2.0)5/2 sin (24.5o)

16 (1) (2650 & 1025) (1 & 0.4)

Using del Valle, Medina, and Losada's relationship (*K *= 0.12)

(1025) (9.81)1/2

(2.0)5/2 sin (24.5o)

16 (2650 & 1025) (1 & 0.4)

It is noted that the estimates of the transport rate developed from the two relationships for *K*,

Equations 2-8 and 2-10, differ by a factor of almost 1.9. This serves to highlight the uncertainty

associated with selection of the appropriate *K *coefficient for a given site, and the resulting uncertainty

in the prediction of the longshore transport rate's value. The grain size used in this problem is much

larger than that typically found on U.S. beaches, and the *K *coefficient found is correspondingly smaller

than that recommended in *Shore Protection Manual *(1984).

Longshore Sediment Transport

III-2-17

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