Flood and inundation mapping, and the names it goes by

432 of the 1,264 Australian suburbs published on this site carry a flood or inundation overlay of some kind. That is a count of our own published pages, not of every suburb in the country — the corpus grows, and this page is rebuilt with it. They span 5 states, and across them this single hazard is mapped under 31 different overlay names.

That is not a curiosity. It is the most common reason a homeowner concludes their block is not flood-affected: they searched the term they had heard, their state publishes it under another, and nothing came back. The names below are all of them we have read.

New South Wales does not appear on this page at all, and that is not a statement about New South Wales flooding. It is a statement about publishing: flood planning levels there are set by each council rather than issued as a state-wide mapped layer we can read per suburb. A New South Wales reader who searches this page, finds nothing, and concludes their block is clear has drawn exactly the wrong inference — the right move is to ask the council for the flood planning level at the address, which our New South Wales suburb pages say individually.

Several of those names separate coastal inundation and storm tide from river flooding, and the distinction is real rather than administrative. River flooding is driven by catchment rainfall and arrives down a valley; coastal inundation is driven by tide, surge and sea level and arrives from the water body a suburb fronts. A block can sit in one and not the other, and the engineering answers differ.

170 of these suburbs carry a coastal or storm-tide mapping specifically, and 135 carry both kinds at once. Where both apply, the floor level that governs is whichever is higher, so establishing which hazard a quoted level was derived from is a real question and not a technicality. The classification here is ours, read off the overlay names — the states publish them, we have grouped them.

55 of these suburbs carry a floodway mapping. A floodway is not the same as land that merely gets wet: it carries active flow during a flood, and because obstructing it pushes water onto someone else, it is typically the most restrictive flood designation a state has. If your block is in one, that fact outranks most of what else is on your planning certificate.