Why doesn’t Victoria have as many floods?
Victoria’s claim to fame in disasters is that it’s the most bushfire-prone region in the world (followed by California and Greece).
Fire risk also comes from climate. Victoria’s temperate climate means dry summers and less rain than its northern counterparts – around 520 millimetres of rain a year falls on average in Melbourne, compared to 1175mm a year in Sydney and 1149mm in Brisbane. Up north, rain tends to fall intensely, whereas Victoria’s rain tends to fall more as drizzle.
What’s different this time? September was wetter and colder than usual in Victoria, which meant the ground was already saturated in many areas. Colder weather means less water evaporates. Together, that made the state primed for floods.
For a flood to happen, you need a high rate of run-off, where rain hits saturated soils and flows overland rather than sinking in, as well as intense rains in a short period.
Rain has fallen across almost all of Australia’s mainland in the last two weeks. Our rain events are usually regional – not national like this.
Source: Floods in Victoria are uncommon. Here’s why they’re happening now – and how they compare to the past