Water Quality Modelling of Cattai Creek Catchment

The Cattai Creek catchment is largely rural at present. The Department of Planning has identified its upper catchment as economically viable to undergo urban development. The urban expansion and population growth will increase the diffused source pollution as well as produce more treated effluent. The Sydney Water Board has developed the Cattai Creek catchment model to assist the assessment and management of water quality in this catchment as well as contribute to the management of water quality in the Hawkesbury - Nepean River system as a whole. The catchment model is based on HSPF programs and developed with recent data from AWT Science and Environment. This paper reports the model setup as well as hydrological and water quality calibrations. Eight water quality variables have been calibrated. An approach to model the complex algal community is also reported. Model simulations on the effect of STP inputs on the flow characteristic at Pitt Town Road site is included.