Virtual River

What is flooding?

Flooding is a natural and inevitable process. Floods occur when a river's channel cannot hold all the water supplied to it by its watershed (the area the river drains).

When a river floods in the lower part of a watershed, the water spill out onto a floodplain, which is a flat area immediately adjacent to the river channel that has been built by river (fluvial) processes. Flat areas that lie above the floodplain are called terraces and often reflect some past climate conditions (such as the last ice age when there may have been more rainfall and more river flow.)

Use your mouse to click the "blue" button in the diagram above to show the area covered by water during low flow, bank full, and flood stage. Then answer these questions.

1. Does the floodplain in the diagram become completely covered with water when the river is at its flood stage?
Yes No Only in the "bank full" condition.

2. Do the stream terraces become flooded?
Yes No Only on the right side of the stream.