The Murray River in south-eastern Australia, one of the world's oldest and slowest rivers, meanders more than 2000 km across a dry ancient landscape from the mountains to the sea, following a course evolved over millions of years. The Darling River winds over an even longer distance from the mountains on the east coast of Queensland to join the Murray River at Wentworth in the semi-arid western lowland plains. These river systems are full of mysteries,...