Here you need to input the breaking wave height and wave angle to determine Q, the longshore sediment transport. There is also an empirical constant K that needs to be supplied. Experiments have shown that K is about 0.7. To also determine G, the shoreline diffusivity, you need to input some geometry of the beach profile--the berm height and the depth of closure (the depth beyond which the profile does not change with time).

Assumed values: sand porosity = 0.3, specific gravity of sand= 2.65, breaking index = 0.78. To change the output values of Q and G for a different value of porosity (p), multiply the output values by (1-0.3)/(1-p). For a different specific gravity (s), multiply the output by (2.65 - 1)/(s-1).

The formula used to calculate Q is:

Q = K E_b *C_b*sin(t)*cos(t)/(rho*g*(s-1)*(1-p)
where
K is an empirical coefficient, taken as 0.77
E_b wave energy at breaking
C_b group velocity at breaking
t wave angle at breaking
rho density of water
g acceleration of gravity
s specific gravity of sand
p porosity of sand

Comments: Robert A. Dalrymple
Center for Applied Coastal Research
University of Delaware, Newark DE 19716
USA