Using Bayesian Networks for Water Quality Prediction in

Sydney Harbour

Interim PresentationName: Shannon Watson

Supervisors: Ann Nicholson & Charles Twardy

Introduction The application domain Bayesian Networks Knowledge Engineering Conclusion

The domain Water quality issue within

the Sydney community for recreation use

Beach watch program to monitor water quality using visual indicators

- is pollution showing etc

But bacteria sampling shows that visually appealing water can contain harmful pathogens

Test beaches for bacteria

The domain Deep ocean outfalls were commissioned

Reduction in levels of bacteria -improved water quality

The domain Beaches in the harbour

still have high levels of bacteria though,

No bacteria entering through sewage

Only surface runoff/storm water overflow

Have tried to understand the relationship through modeling

Past studies Hose et al. used multi

dimension scaling model of Sydney harbour

unable to handle the noisy bacteria samples

Other models Wasps / CE-QAUL-W2- used in the US to model estuaries

EPA in Sydney want a model that can use knowledge of causal structure

Sydney Harbour Modeling the pollution(bacteria) in

the harbour- Using Bayesian networks

- Can handle noisy data sets - Take advantage of causal

structure

Bayesian Networks Graphical structure allows non-

technical people to understand a technical model.

Have been used by R.J. Kennett, a past honours student at Monash, to predict the sea breeze

Bayesian Networks – An example

Decide_Umbrella

Take ItLeave At...

Forecast

SunnyCloudyRainy

33.333.333.3

Weather

No RainRain

50.050.0

Satisfaction

Example cont.

Decide_Umbrella

Take ItLeave At...

Forecast

SunnyCloudyRainy

53.521.525.0

Weather

No RainRain

70.030.0

Satisfaction

Knowledge Engineering Used to keep structure of large projects in

software engineering discipline Two major implementations

-Spiral model/Waterfall Model Demonstrate how Knowledge Engineering can

be used in the application of Bayesian Networks, as there is currently no literature on how to create large Bayesian networks

Spiral Model

Conclusion Use Bayesian networks Create a model of Sydney harbour Aim to predict the water quality for

EPA Use Spiral Model

Questions