The theory of nonuniform alongshore currents is reviewed for the one dimensional ease neglecting convective acceleration terms and assuming variations in surf zone width are negligible. An equation for the alongshore current velocity which takes account of the relative effects of the breaker angle and an alongshore wave height gradient is obtained. The magnitudes of the two constants Kθ and K∆H in this equation are found to depend upon both the particular representative velocity selected and the amount of lateral mixing within the surf zone. Recent field and laboratory data are used to obtain the magnitude of lateral mixing factors for various representative surf zone velocities and to estimate the average value of the friction factor fwc as well as of the ratio (tan α)/fwc.
The CERC-Scripps formula for alongshore transport is modified to include the effect of an alongshore wave height gradient as well as the effect of breaker angle. The resulting equation .has two constants, a scale factor Ks for the alongshore transport rate and the constant K∆H which determines the proper balance between the two driving force terms. The magnitude of Ks is a function of breaker type. Potential causes of error in computing the alongshore sediment transport from this one dimensional "black box" type of equation are discussed.