The performance of the sydney flood warning system, august 1986

During August 1986 Sydney experienced its worst flooding for decades. Some 2,500 properties were flooded and transport was severely disrupted in much of the metropolitan area. The flood provided an opportunity to examine the operation of a warning system in a major Australian city. Pre-existing research into flood warnings was expanded to take advantage of the opportunity. The warning system is examined in terms of: its impact on flood losses; consumer satisfaction; and inefficiences or breakdowns within the system. Much of the flooded area was not covered by a formal warning system. For the area that was covered, performance could be improved. Problems were experienced with the data collection and transmission network. Warning dissemination was inadequate, and the majority of those surveyed claimed that they did not receive warnings. The actions of householders reduced the flood damage substantially, but this does not appear to be the result of official warnings. Key recommendations concern improving the reliability of the flood detection network and information management.