The city of Toowoomba , in the Darling Downs , was hit by flash flooding after more than 160 m of rain fell in 36 hours to 10 January 2011 . This event caused four deaths in a matter of hours . The city of Toowoomba , in the Darling Downs , was hit by flash flooding after more than 160 m of rain fell in 36 hours to 10 January 2011 ; this event caused four deaths in a matter of hours .