gbr catchment scale modelling, gillian mc closkey
TRANSCRIPT
Source Catchments Paddock to Reef integrated Monitoring and
Modelling Program
Dr Gillian McCloskey
DERM Senior Catchment Modeller
Reef WQ Targets By 2013, at the end of catchment there will be a minimum: 50% Reduction in Nitrogen & Phosphorus 50% Reduction in pesticides, and 50% late dry season groundcover on dry tropical grazing land By 2020, at the end of catchment there will be a minimum 20% reduction in sediment loads
Banti Fentie Rob Ellis Cameron Dougall Louise Hateley Gill McCloskey Helle Vittinghus
Model Key Objectives
Modelled load estimates for: • Pre-European • Baseline 2008 -2009 • Annual report cards for 3 yrs
To assess and report on progress towards meeting Reef Water Quality targets
Simulate and quantify impact of current and improved management practises on stream constituents, loads and water quality in the GBR catchments
Region Size Km2
Climate Zone
Rainfall (mm/yr)
Dominant Land use
Cape York 42,793 Tropical 800 - 2400
Grazing 52% Nature
Conservation 46%
Wet Tropics 22,000 Tropical 716 – 3015
Grazing 46 % Nature
conservation 33 % Sugar 9 %
Burdekin 138,245 Dry tropics
649 - 1800
Grazing 94 % Forest and Nature Conservation 2.5 %
Sugar cane 1 %
Mackay /
Whitsundays
9021 Dry tropics
600 - 3000
Grazing 47 % Forest and Nature Conservation 26 %
Sugar 19 %
Fitzroy 142,000 Dry tropics/
Sub tropics
526 - 2065
Grazing 82 % Forest and Nature Conservation 9.4 %
Cropping 6.7 %
Burnett/ Mary
51,722 Sub tropics
600-2000 Grazing 78% Forest 15.5 %
Cropping 4.3 %
Total modelled Area = 361488 km2
Whole GBR catchment needs to be comparable and as close to real life as possible
– Loads quantifiable – one number – Same scale and time step: sub catchments and daily – Functional units: 9 standard, up to 3 regional FU’s – Storages, Extractions and Inflow as per DERM Water Planning – Same rules for gauge inclusion; Quality codes and time series
Model Setup in Source Catchments
• 1 Outlet: All sub catchment with GBR outlet runs through one outlet node
• Landuse in to 11 Functional units
• Storages added as Link models, Storage-demand added as node models on the node immediately downstream
• Water extractions added as node models
• Gauges used for calibration from 1970 – 2010, sorted by min 10 years data, not downstream of a storage
Model Setup Whole GBR Catchment and each region
Source Catchment Components Region Number of Sub
catchment Size of Sub
catchment in km2 Number of nodes/
links Storages Extractions after
IQQM
Cape York 545 50 546/545 - -
Wet Tropics 450 30 451/450 2 2
Burdekin 1564 50 1565/1564 5 10
Mackay /
Whitsundays
191 30 192/191 9 5/2
Fitzroy 1600 50 1601/1600 ? ?/?
Burnett/ Mary
597 50 598/597 14 22
Hydrology Calibration - PEST PEST – Parameter Estimation Tool
GBR Models – size, number of FU’s
Each FU has a RR model, & each RR model has many parameters (SimHyd – 9)
CYP example – 545 subcatchments, 10 FU’s, 7 adjustable SimHyd params, 2 routing parameters = 49050
Too many parameters! Will affect computing power.
Hydrology Calibration - PEST Condense number of FU’s (no. of FU’s x no. of regions x 7 adjustable SimHyd params) + (no. of regions x 2 flow routing params) = 414 parameters (in Cape York)
Objectives: Daily Nash-Sutcliffe of 0.5, Monthly NS of 0.8 and modelled vs measured flows within 10-20%
Initial approach – regionalisation regions based on areas with similar rainfall, soil type & geology etc
Next approach – one region per gauge
• 14 gauges (all three objective functions met)
• 3 gauges (two objective functions met)
• 1 gauge (one objective function met)
Parameterisation 1 Parameterisation 2 Parameterisation 3 Parameterisation 4 Parameterisation 5
Hydrology Calibration - PEST
End of system Barron River 110001A
Picnic Crossing head waters of the Barron 110003A
Flaggy Creek Rainforest 110011B
Where we are at
Dynamic SedNet testing: in progress
Incorporation of paddock scale modelling outputs
Report due: 30 May. This year. (Dave: how many days is that?)
Whats next future