Australia's inland rivers occur across the vast, predominantly arid regions of the continent, comprising 70% of its land area. Some, like the Murray-Darling eventually flow out to sea, whilst others like the Diamantina and Cooper Creek, flow inland to Lake Eyre. These river systems have highly variable flows, they come and go, flood large wetlands or lakes, wet vast floodplains, create new watercourses and dry out to meandering braided channels, billabongs and waterholes. They are fed by thousands of small creeks, and these 'arteries' drive ecological processes, create habitat for plants and animals and provide water for industry, irrigation, electricity generation and domestic use.