Sydney harbour observatory IS PROVIDING DATA THAT WILL HELP TO ADDRESS THE QUESTION OF HOW RECREATION, COMMERCIAL ACTIVITIES, PRIMARY PRODUCTIVITY AND THE ECOLOGY OF SYDNEY HARBOUR WILL BE AFFECTED BY CHANGES IN THE ENVIRONMENT.
The health of Sydney Harbour depends on many processes and these processes need to be isolated and understood if we are to maintain and improve the amenity of the harbour. Here you will find examples of archival data collected by the Sydney Harbour Observatory, based on the various processes and variables that reflect a change in the water environment and affect the health of the harbour.
To help identify pollutant paths, measure and predict nutrient levels and to continue to reduce the concentration of heavy metals, pathagens and toxins we have taken the Environmental Fluid Dynamic Code, EFDC, and supplied the boundary conditions to provide a real time Harbour model. To support the real time model we have developed a sensor hub to allow real time observation of properties such as salinity, temperature and chlorophyll to be obtained at Harbour "hot spots". The observations are automatically sent back to the Observatory for collation and analysis. Every month the sensors need to be cleaned. Calibrations and quality control is required. Some samples of data collated from both the real-time model and our sensors is shown below.
The real-time model predicts properties such as the surface salinity which is reproduced in the figure below. Fresh water from recent rain over the catchment is less dense and more polluted than the ocean and the harbour water, however it does not mix easily with the harbour water due to the difference in density. Pollutants are trapped in the lower salinity water and travel quickly down the estuary and out to sea. This is a snapshot of the salinity in the harbour on the 15th june 2013. The areas of lower salinity tend to be areas of higher pollutants.
The shallow nature of the harbour in this region also shows some interesting temperature changes. An example of the complex situation is shown below:
The peaks on the graph below are caused by the tide sweeping water backwards and forwards past the sensor. There was a sharp drop in temperature at this location on 2 July, 2015 that was larger than the tidally induced fluctuations.
Collected from Long Bay, between Northbridge and Cammeray (Long Bay)
22/07/15 to 16/08/15.
Moving closer to the Spit Bridge at the location shown below. In situations of complex flow such a the Spit Bridge we need to gain confidence that the model is adequate. If not, local adjustment can be made. Possibly sediment deposition has changed the depth of the sea floor. Collected from Middle Harbour (near the Spit Bridge) 9/04/15 to 1/05/15.
Between April 9th and May 1st, 2015, the salinity dropped after a rain storm (due to the freshwater in the rain and running off the land.) The flow of nutrients from the land run-off caused the chlorophyl levels to increase over the next few days.