18. which of the following is not correct about floodplains? they have recurrent problems with flooding the streams have natural levees adjacent to them othey are generally low-lying areas they are characterized by rapids and waterfalls

The statement that they are characterized by rapids and waterfalls is incorrect about floodplains.

Explanation:

All other points mentioned holds for flood plains:

Most of the floodplains are low lying areasThey are generally, the land areas which are adjacent to streams and riversThey are subjected to repeated influx or flooding.They can be simply characterized by a relatively smooth land area on whose boundary lies water stream or river which overflows or results in flooding at the time when water is high.

Answeroil-shale;

Answer b is the answet