21 February 2011 Tony Weber eWater Tools in Action – The Tamar and Esk Rivers Sediment Modelling using Source Catchments eWater Road Show 21 Feb – Part 2 of 5

Background Sediment in the Tamar Estuary – Some Questions How much? Where is it coming from? Who might be contributing? What might the causes be? Will it get worse? How do we fix it?

Background How to model using Source Catchments Collect Data Understand the catchment Build a model Check it is OK Extract results Check it is OK Produce final results

Mapping the Catchment Major Catchments

Mapping the Catchment Land Use

Mapping the Catchment Point Sources

Building the Model Subcatchment Definition

Building the Model Node Link Network

Building the Model Water Flow Gauging stations Real data

Building the Model Water Quality

Model Analysis and Uncertainty Needed to examine how “good” the model was It’s possible that random numbers can be just as good So ran 1000’s of parameter sets through the model Compared to the “calibrated” results Gave us an understanding of the uncertainty Allowed us to refine the parameters significantly to reduce uncertainty Also identified which parameters could be reliably derived from the data

Model Analysis and Uncertainty

Model Results Basin Loads – TSS % Distribution

Model Results Broad Land Use Loads – TSS

Model Results Spatial Distribution – TSS Mean Annual Loads 0 t/yr 3300 t/yr

Model Results Examining Scenarios

What does this all mean? Sediment Sources

Learnings TEER Catchment Modelling Some of the most detailed modelling in Australia High degree of certainty in results Indicated areas to focus future management These are simply tools and should be used as such Partnering with industry – a two way street!

NEXT – Australia’s next gen modelling platform Dr Peter Wallbrink