Shoalhaven river mouth: a retrospective analysis of breaching using aerial photography, landsatimagery and LiDAR

The Shoalhavenriver, located on the wave-dominated south coast of eastern Australia, has the 6th biggest catchment area (7,151 km2)that debouches in NSW waters. Although the river mouth is breached during floods, most of the time the normal flow is diverted through an artificially dug canal and only reaches the ocean at Crookhaven Heads. A search throughout LandSat archives and aerial photographs from 1949 has shown not only that the river mouth was opened in 1961, 1974-1980,1988-1994 and at the end of 1999, but also revealed that dune vegetation has been developing as increasingsand closes the river mouth. Nowadays, the river outlet is sealed by a 200-m wide sand deposit that ranges in elevation from 2.1 to 5.4 m above mean sea level.Historical comparison of LiDAR data also demonstrated the widening of Berry's canal as erosion takes place on its flanks. These findings provide usefulevidence for a sediment budget approach to coastal management to be developed in this coastal compartment.