Modelling of pollutant load reductions is based on reported improvement in management practice systems. Results are an estimate of the annual average reduction in human-caused (anthropogenic) pollutant loads at the end of catchments.
About the indicators
The catchment loads modelling program estimates average annual loads of key pollutants (sediment, nutrients and pesticides) for each of the 35 catchments draining to the Great Barrier Reef. It models the anthropogenic baseline load and the change in loads for each subsequent year due to the adoption of improved land management practices. For more information, refer to Why use modelling to measure catchment loads?
A standardised scoring system was developed for each key indicator in the report card. The scoring system is used to access and communicate progress towards the catchment targets using the following categories
|Poor||Very poor||No data|
Further details on the scoring system (PDF, 596K) for each indicator are outlined in the supporting technical information.
Dissolved inorganic nitrogen
Reduction in annual average dissolved inorganic nitrogen load between 2009 and 2014. Target: 50% by 2018.
|Great Barrier Reef||17.0%||Poor|
|Wet Tropics||14.5%||Very poor|
|Burnett Mary||31.5%||Very good|
Reduction in annual average particulate nitrogen load between 2009 and 2014. Target: 20% by 2018.
|Great Barrier Reef||11.5%||Good|
|Burnett Mary||6.0%||Very poor|
Reduction in annual average particulate phosphorus load between 2009 and 2014. Target: 20% by 2018.
|Great Barrier Reef||14.5%||Very good|
|Cape York||12.0%||Very good|
|Wet Tropics||20.5%||Very good|
|Mackay Whitsunday||13.0%||Very good|
|Burnett Mary||12.0%||Very good|
Reduction in annual average sediment load between 2009 and 2014. Target: 20% by 2018.
|Great Barrier Reef||12.0%||Very good|
|Wet Tropics||13.5%||Very good|
|Burnett Mary||3.0%||Very poor|
Reduction in annual average toxic pesticide load between 2009 and 2014. Target: 60% by 2018.
|Great Barrier Reef||30.5%||Good|
|Mackay Whitsunday||41.0%||Very good|
Read the detailed Catchment pollutant loads results (PDF, 800 KB).
Monitored pollutant loads leaving catchments vary significantly from year-to-year, mainly due to differences in annual rainfall and runoff. Therefore, catchment modelling is used to estimate the long-term annual pollutant load reductions due to the adoption of improved land management practices. This removes the impact of factors such as climate variability. Research suggests time lags to monitor the improvements from land management practice change could range from years for pesticides up to decades for nutrients and sediments, due to the high level of climate variability. The models use measured changes in on ground management and well-documented and accepted methods and assumptions. Long-term water quality monitoring data is used to validate and improve the models, continuously improving confidence in the estimates of water quality over time.
Example of modelled loads for natural (pre-development), human caused (anthropogenic) and the load reduction following investment in improved practices. The pollutant loads targets aim to reduce the anthropogenic load leaving catchments.