Impact of river training walls on adjacent beaches, Ballina, New South Wales, Australia

River and inlet training walls have been built at scores of locations along the NSW coast. This study examines the impact of training walls built at the Richmond River mouth, Ballina, over the period 1889 to 1991 on the adjacent beach systems. GIS analysis of 2 bathymetric maps and photogrammetric analysis of 6 aerial photo sets were used. The position of the shoreline and contours and their temporal changes for each profile were determined to identify accretional and erosional patterns. Spatial variations in the pattern were then used to assess the impact of training walls. The impact of training wall can be divided into three types: (1) accretion in updrift and erosion in downdrift; (2) accretion on both sides of the training wall, and (3) accretion on both sides near the training wall, but erosion on both sides away from the training wall. South Ballina beach and Lighthouse beach exemplify the second type. The impact of training wall varies linearly with the distance from the wall.