Dubbo Flood Study Report

A detailed study of flood behaviour of the Macquarie River at Dubbo has been undertaken. The peak discharge for the 100 years event was estimated taking into account the behaviour of Burrendong Dam and a joint flood frequency study with flows from the Bell River. Flood levels, flood velocities and the floodway limits were determined for the 100 year event using the HEC-2 water surface profile computer program. A preliminary assessment of flood damages in Dubbo showed that the average annual damages are in the order of $137,000. Under 100 years flood conditions approximately 15 residential properties and 47 commercial properties would be inundated by floodwaters up to 2.9m deep. The presence an operation of Burrendong Dam has been assessed as significantly reducing the impact of flooding at Dubbo. Additional structural mitigation measures have not been recommended. Non structural methods in particular flood warning and flood awareness strategies and development controls are considered to be appropriate measures for Dubbo. For verification of the hydraulic model and the monitoring of future floods, it is recommended that a system of peak flood level indicators be installed. It is also recommended that for floods that exceed 9m on the Pump Station gauge additional peak flood levels be obtained throughout the study. obtatned .thrgMflput t2w .ud