Natural hazards threaten everybody living in vulnerable areas. With the increasing concentration of people, infrastructure and facilities in them, urban areas are becoming particularly vulnerable to hazards (Pelling 2003, Perrow 2007). Hazards become disasters when they impact on human beings and their artefacts. The people and institutions involved include, amongst others, those participating in the land use planning process. This paper deals with three aspects of flood hazards that are crucial for an understanding their interactions with land use planning. One is the nature of flood hazards themselves, because many aspects of these are not widely appreciated. The second is the particularly difficult problem of retrofitting settlements for floods. It is far easier to plan for floods in greenfield settings than it is to try to correct past misjudgements that affect already built up areas. But first the paper provides a framework for the discussion, extending that of governance (Minnery, 2007) into an urban institutional framework.