Estuary Entrance Condition

Data was collected for two variables: the presence of one or more breakwaters or training walls at the estuary entrance and the level at which some intermittently closed estuaries are artificially opened by the responsible management body, either local government or the National Parks and Wildlife Service. Aerial photography was used to detect whether an entrance was trained and whether the rock protection occurred on both sides. For artificially opened entrances, coastal councils and DECCW regional offices were contacted for existing records and/or personal knowledge of the level at which the entrance is opened.; ; Tidal flow can be affected by breakwaters or training walls built to keep estuary entrances open and the artificial opening of lagoon entrances for flood mitigation, water quality, fish and prawn recruitment and other purposes. Both result in an increase in salinity levels, tidal ranges and flushing which can alter water quality, the distribution and composition of aquatic vegetation and animal species and ecological processes. Entrance training can also increase the erosion of inlet channels altering sediment processes and feeding back into even larger tidal ranges. Artificial opening at levels below natural can also lower frequency of inundation of peripheral vegetation such as saltmarsh and reeds.