A floodplain is the area of flat land adjacent to a river, creek, lake, estuary, dam or artificial channel which is subject to flooding during high rainfall periods. It is considered that such land is not financially feasible to be protected against flooding.
A floodplain has two main functions:
- temporary storage to attenuate flood effects, and
- an expanded flow path
Increasing urbanisation reducese the effectiveness of the floodplain's functions.