Australia - The land of the Floodplain (White, 2003)

Like just about everything in Australia, the hydrology is different from the rest of the world. On the Australian continent the only drainage systems flowing to the sea are around the coastal fringe. The rest of the land surface is inward draining. Some of the biggest flows go to Lake Eyre, though the run-off often evaporates and sinks into the bone-dry sand along the desert water courses. As a result the only river systems to be affected by the rise and fall of the oceans are the coastal systems. The marine incursions over large areas of the the land surface has resulted from the subsidence of the basins of the inland areas several times during the continent's long history.

Australia has been called 'the land of the floodplain', because about 3/4 of the continent is covered by the drainage systems of inward-draining rivers, often heading towards the lowest point, Lake Eyre. These floodplains are very wide because of the low gradient over most of the length of the rivers that bring the flood waters that result from heavy monsoonal rains of the wet season in the north of the continent. When floods move down the main channels of the rivers of the Channel Country heading for Lake Eyre the water soon overflows the banks of these rivers that in many places are normally dry between floods, and spreads over vast areas of flat ground and the many minor channels.

It has been found that beneath these floodplains, that are dry when not in flood from heavy rains near their headwaters, there are palaeoriver channels and the associated floodplains, that have been filled by sand during glacial phases, when Australia was very windy and aeolian sand was deposited in dunes over about 80 % of the continent. In the arid interior, where there is little surface water, even when not in actual drought, it has become clear that many surface ecosystems are maintained between floods by the presence of the water retained in the porous sediments of the immense expanses of sand-buried flood plains across the interior. During glacial phases the palaeoriver valleys and floodplains were often buried by deep layers of windblown sand. This sand now make it possible for rivers that appear to end in a swamp or billabong to actually continue flowing, but as subsurface rivers through the sand.