NERP TE Project 4.1 Tracking coastal turbidity over time and demonstrating the effects of river discharge events on regional turbidity in the GBR (AIMS)

Brief description

Turbidity is a measure of water clarity that quantifies the amount of small particles suspended in the water, and is a fundamental environmental parameter influencing coastal marine ecosystems. Turbidity reduces the light needed for photosynthesis by corals and seagrasses, and suspended particles also transport nutrients, pollutants and diseases. Previous research based on 3 years of turbidity data collected from 15 inshore reefs by the Reef Rescue Marine Monitoring Program has shown that it can take several months for water clarity to improve after river floods. This project will analyse a 12-year data set to demonstrate the explicit link between variations in discharge (sediments and nutrients) from the major rivers in each Natural Resource Management (NRM) region adjacent to the Great Barrier Reef (GBR) and seasonal and annual variations in water clarity in the inshore GBR.

This project will:

1. Determine quantitative relationships between river discharges and seasonal and annual variation in inshore water clarity on the GBR adjacent to each NRM region. This is achieved by processing MODIS/Aqua remote sensing (since July 2002) to calculate euphotic depth (water clarity) for the whole GBR and analysing this against predicted and observed tides, observed waves, wind, rain, river flow data (BOM and DERM daily data) and tidal forcing (Slim model).

2. Strengthen scientific basis for Reef Rescue and Reef Plan and the refinement of water quality targets.

3. Provide data to assist validation and calibration of the Receiving Waters Model and a WQ Risk Analysis.

This project is now complete.

Notes

Credit
Katharina Fabricius (AIMS), Statistician (AIMS), Sam Noonan (AIMS), Jon Brodie (JCU), Eric Wolanski (JCU), Scarla Weeks (UQ), Marites Canto (UQ)

Purpose
Quantification of the relationship between terrestrial run-off and turbidity is critical to demonstrate that water quality in the inshore GBR can be improved through improved land management in adjacent catchments. The new knowledge generated by this project will improve the scientific basis underpinning the Australian Government’s Reef Rescue program, Reef Plan and the refinement of water quality targets. The project will also determine the spatial extent of declining water quality on the inshore GBR and allow validation and calibration of a Receiving Waters Model.