Billabongs
As the River travels through this flat stretch of land it starts to wander back and forth. This meandering cause large curves in the river to form. The current of the river is always pushing and eroding the outside of the curve causing it to grow and cut farther and farther into the land. This is because the fastest part of the current is forced to flow along the outside curve, due to inertia. The faster the current the more sediment it can carry. And as a result, the outside bank is eroded away.
Over time the meanders become more and more pronounced (Stone, 1974, p64). The outside curve is eventually eroded away until the two sides of the river on each side of the neck of land flood over and meet, cutting off the out route of the river and forming a new channel for the main current.
Eventually more sediments are washed up and completely block off the old section of the river, forming an oxbow lake, better known as a billabong in Australia (www.geocaching.com).
Billabongs held water for longer than other parts of the river and as such were a very valuable source of water especially along the Murray that has been known to run completely dry before water management strategies were put in place(www.geocaching.com).