These desert rivers occur mostly in flat areas of arid and semi-arid mid-latitudes. Channels are typically broad, flat, and often branching, with soft sandy sediments. They are dry most of the time, but punctuated by high-volume, short duration flows that transport nutrients and stimulate high productivity by algae and zooplankton. Plants and animals can either tolerate or avoid long, dry periods and then exploit short pulses of abundant resources, producing hotspots of biodiversity and ecological activity in arid landscapes.