Bureau of Meteorology forecaster Chris Leahy told me about an interesting hydrologic oddity in Australia. Cooper's Creek is the only place where "Two rivers meet to form a creek." Wikipedia describes Cooper's Creek as "One of the most famous, yet least visited rivers in Australia".
|A map of Australia's outback rivers|
When he discovered it in a dry year, misguided explorer Charles Sturt named it 'Cooper's' after Charles Cooper (then [South Australia's] Chief Justice) and 'Creek' because he didn't think anything that small was actually a river!
|Scott Bridle's aerial photo of flood patterns. His website has many more good photos of Australian landscapes taken from above.|
Often the interior of Australia is completely dry and there is no surface flow. But when it flows, it flows everywhere. There is not so much a river channel as there is the "channel lands".
|A satellite image of where the rivers come together to form a "creek"|
There's many words for water flowing in channels and there's no standard definitions. Here are some of the ones I have known, roughly from my notion of largest to smallest:
There's similar debates about how to describe the land surface area that drains into a channel.
Many people also use sub-catchment, sub-area and so on, adding another layer of complexity (e.g. which is bigger, a sub-watershed or catchment?)
My rule of thumb when living in Arizona was that a river was anything you couldn't jump across. I learned this by unsuccessfully trying to jump across the Gila River.