Billabong word (billa =river, bong = dead)... is used for an isolated pond that is left behind after a river changes course. Billabongs are usually formed when the path of a creek or river changes, leaving the former branch with a dead end. Billabongs, reflecting the arid Australian climate in which these "dead rivers" are found, fill with water seasonally and are dry for a greater part of the year. Billabongs attained significance as they held water longer than parts of rivers and it was therefore important for people to name these areas. _Wikipedia