Sand Bypassing at the Tweed River Entrance, Vol. 1 Investigations, and Vol. 2 Data Collection and Assessment. July 1986.

Abstract

This report details an investigation of the natural sand bypassing processes which control the development of the ebb tidal delta at the trained entrance of the Tweed River. The training has had a major influence on the longshore supply of sand to the beaches to the north. The study entailed the collection and assessment of existing data pertaining to the to the Tweed River and lower Gold Coast region. In addition, field investigations have been undertaken including offshore drogue tracking, side-scan sonar and seismic profiling, bed sediment sampling and stream gauging. Results have shown that there is a complex interaction between the ebb jet, littoral, offshore currents at the entrance influencing the formation of a dynamically stable ebb tidal delta and the bypassing of the littoral sand supply. This and other factors make inadequate the use of commonly used procedures to investigate the effect of training walls on beach stability.