The Local Government Engineer and Coastal Erosion

The recent realization that littoral drift is pulsational rather than uniform throughout the year has significant engineering consequences. These pulses or humps of material occur after each storm and have longer term fluctuations due to limited concentrations of wave energy on the coast and the influence of man in impeding transport by marine structures and dredging channels across the shelf. It is shown that time honoured remedial measures for erosion such as groynes, seawalls and renourishment have little to commend them. The alternative approach of headland control is seen to copy Nature's method of limiting longshore transport and furnishing the storm waves with sand to construct the protective offshore bar. The resulting zeta shaped bays have predictable indentation and curvature, once the obliquity of the persistent swell waves is known, for the case of no further sand supply. This permits encroachment lines to be determined with confidence. Economic means of constructing such headlands is discussed.