Great Barrier Reef Source Water Quality Modelling Rob Ellis, Dave Waters, Chris Carroll, Gill McCloskey, Louise Hateley, Bob Packett, Cam Dougall, Banti Fentie This presentation • Background to Reef Plan Development • Multiple lines of evidence approach • Catchment Modelling Approach • Reef Report Card 2 outputs & Scenarios • Summary The Great Barrier Reef 2,300 km along the Queensland coast 2,900 reefs plus seagrass meadows, mangroves and other habitats Biodiversity of international significance World heritage area A Billion dollar tourist industry Declining water quality prompted the development of the Reef Water Quality Protection Plan (2003 then 2009) 50% decline in coral cover since 1985 30 De'ath et al (2012) 20 10 1985 2010 Risk: Coral cover is collapsing • Crown-of-Thorns starfish major cause of the decline • Outbreaks more prevalent where high nutrient runoff • Fertiliser increases linked to increased Starfish fertility • If no Crown-of-Thorns Starfish, cover would’ve increased by 24% • Outbreaks now every 12-15 yrs, not once every 100 years • No decline in undeveloped northern region Reef Water Quality Protection Plan Declining water quality prompted development of reef plan Joint initiative of the Qld/Australian Governments Focus on pollution from agriculture Plan defines a set of water quality targets Government are investing in improved Management practices to meet targets Reef Water Quality Targets By 2013, at the end of catchment there will be a minimum: • 50% Reduction in nitrogen & phosphorus • 50% Reduction in Pesticides, and By 2020, at the end of catchment there will be a minimum • 20% reduction in sediment loads Novel approach using 5 lines of evidence 5.Ecosystem 1. Practice 2. Prevalence of 3. Water Quality 4. Water Quality Outcomes Effectiveness Practices, extent Reductions Outcomes (Catchment modelling) (Marine monitoring (monitoring & modelling) (ABCD framework) (Long-term monitoring) program) Simulations Land Use Sub- Bare basin Ground Basin Plot Index Riparian Paddock Wetlands Catchment Modelling Elements Source Catchments Framework The Models • Models used to report on progress towards meeting these targets • Built 6 catchment models • 35 Catchments in total (423,000 km2) • Modelling sediment, nutrients and pesticides • Consistent approach all regions Fixed Modelling period (1986-09) • Matches ground cover index period • Minimal land use change, and • Is a good representative rainfall period Townsville Cairns 3000 4000 3500 2500 3000 2000 2500 1500 2000 1500 1000 Rainfal Rainfal (mm/yr) 1000 500 500 0 0 100 year average rainfall Modelling period average rainfall Modelling Approach 9-12 major land use categories of interest Includes Major Dams/Storages Irrigation extractions Sewage treatment plant inflows • Hillslope, gully and streambank erosion modelled Models validated against 5-6 years GBRI5 load estimates Incorporating a range of paddock scale model outputs for constituent generation How do we represent practice adoption data in the catchment model? Matrix = paddock Distribution Represent landuse and modelling (ABCD) (ABCD) land management in the Model Thousands of combinations Investment in improved management practices Model Validation • Modelled loads validated against 6 years loads monitoring program data Models validated against the measured data Results Catchment Area Cape York Mary-Burnett 10% 13% Wet Tropics 5% Burdekin 33% Fitzroy 37% Mackay- Whitsundays 2% Total 423,000 km2 Average Annual Runoff Mary-Burnett 4% Fitzroy 9% Cape York Mackay- 27% Whitsundays 8% Burdekin Wet Tropics 19% 33% Total 63,864,333 ML/yr Wet Tropics & Cape York contribute 60% of the flow Landuse Area Cropping Cane Other 3% 1% 3% Cons/Forest 18% Grazing 75% Identification of pollutant sources Sediment Mary-Burnett 6% Cape York 4% Wet Tropics 13% Fitzroy 25% Mackay- Whitsundays Burdekin 6% 46% Identification of pollutant sources - TSS kt/yr 0 1,000 2,000 3,000 4,000 Jacky Jacky Creek Olive Pascoe River Lockhart River Cape York Stewart River Normanby River Jeannie River Endeavour River Daintree River Mossman River Barron River Wet Tropics Mulgrave-Russell River Johnstone River Tully River Murray River Herbert River Black River Ross River Burdekin HaughtonRiver Burdekin River Don River Proserpine River Mackay-Whitsunday's O'Connell River Pioneer River Plane Creek Stxy River Shoalwater Creek Fitzroy Water Park Creek Fitzroy River Calliope River Boyne River Baffle Creek Kolan River Burnett River Burnett-Mary Burrum River Mary River Pre-Development Anthropogenic Identification of pollutant sources Anthropogenic TSS by Industry Forestry 6% Other 1% Cropping 6% Sugarcane 10% Grazing 77% Identification of pollutant sources Dissolved Inorganic Nitrogen (DIN) Urban Horticulture 4% 5% Forestry Grazing 2% 28% Cropping 3% Sugarcane 58% Identification of pollutant sources Pesticides PSII(photosystem II) Grazing Cropping Horticulture 2% 4% <1% Cane PSII Sugarcane 94% • 60% WT • 26% MW + Burdekin Identification of pollutant sources 100% 80% 60% Streambank 40% Hillslope 20% Gully 0% So how much improvement was achieved due to the government investment? So how much improvement was achieved due to the government investment? 50 Target 40 30 % 20 10 - TSS TP PP TN DIN PSII Summary Multiple lines of evidence approach key to success of program Source was not initially designed for models of this scale and complexity Can identify priority industries and areas to inform investment Flexibility of the Source modelling framework has allowed us to tailor the models to meet the specific objectives of reef plan Use of ‘fit for purpose’ models for each industry/process we are representing was critical to be able to identify sources Bundaberg January 2013 THANK YOU.