There is no disaster management legislation at the Federal or Commonwealth level in Australia. Our arrangements in particular the activation of DISPLAN and the use of the armed forces are all governed by implied and unstated legal rules.
In a paper that now appears in the Canberra Law Review I have made an argument on why the Commonwealth should pass legislation in this important area. My paper is called “Responding to Catastrophic Natural Disasters and the Need for Commonwealth Legislation”  CanLawRw 30; (2011) 10(3) Canberra Law Review 81. You can find the paper either on the Law Review’s own website, or via the Australian Legal Information Institute (AustLII).
In this paper I also discuss the Canadian emergency management legislation. In Canada there is a federal emergency management minister, a role now filled in Australia by the former Attorney General Robert McLelland. The Canadian model may be a model that could be adopted here, given the current arrangements do not make it clear what the role of this new portfolio is – see my earlier post ‘New Minister for Emergency Management’ (December 12, 2011).