This Study has been prepared by WMAwater on behalf of the Goulburn Mulwaree Council (Council). The main objective of this study is to define mainstream flood behaviour at Goulburn due to the Wollondilly and Mulwaree Rivers. The Study has examined past flood events in addition to undertaking a flood assessment for a range of design storms under existing conditions. The findings in this report provide material to inform Council with regards to managing existing and future flood risk due to mainstream flooding at Goulburn.

The information and results obtained from this study define existing flood behaviour for the Wollondilly and Mulwaree Rivers and provide a firm basis for the development of a subsequent Floodplain Risk Management Study and Plan (FRMS&P). Primarily, the study was developed in order to meet the objective of defining design flood behaviour (0.2 EY, 20%, 10%, 2%, 1%, 0.5% AEP events and the Probable Maximum Flood (PMF)) for mainstream flooding at Goulburn and to produce: Flood levels, extents, velocities and flows for the full range of modelled design events; Provisional hazard and preliminary hydraulic category maps for the 1% AEP and PMF events; Flood emergency response classification of communities; Analysis on the sensitivity of flood behaviour to changes in flood producing rainfall events due to climate change; and *A modelling system to be used in the subsequent FRMS&P to test proposed flood risk management strategies.