Floods can be complicated, but the fundamental cause isn’t: water falls from the sky in volumes too big to be confined within watercourses. These overflow onto flood plains. That’s it.
There can be additional factors, of course: if vegetation in the catchments has been stripped—say, by fire, or unwise clearing—then violent rain can cause massive washaways and erosion. And the disaster is compounded when people have built homes on the flood plain, something Australians have been prone to do for 200 years [see our Post].
This is what happened in the floods which devastated Castlemaine in 1889. Doug Ralph, presenter of the Tuesday history program on Main FM [94.9], has unearthed an interesting contemporary discussion of the event from the Argus newspaper [26/1/89]. The journalist, writing under the name Telemachus, is travelling in this region with George Perrin, Conservator of Forests in Victoria:
Forest Ck-Barkers Ck junction, January 2011: native vegetation along creeks does not increase flood levels. Discussion of the disastrous 1889 floods centred around three factors: the huge dumps of rain; stripping of hillsides of vegetation, which worsened runoff; and degradation of creeks in mining works.
‘”I could make a fine forest there.” Thus Mr. Perrin, as we ran along beyond Taradale towards Castlemaine, through the hills which the diggers tunnelled and honey-combed, and stripped, and left desolate and hideous, over so many Australian leagues…
‘…”Killing out the forest caused all that.” Thus, again, Mr Perrin, as we look down the long valley of Castlemaine, strewn with the wreckage of the late disastrous flood. “Silting up our creek caused all that,” said the townsfolk, sitting in sack cloth and ashes amongst the ruins, and probably the one statement was as near the truth as the other, and both a good way off. I believe still that flood was one of the few incidents which may fairly be described as an act of God. The powers of nature gathered those clouds together, and the