Theory question 306
Rivers and River Landforms(a) What is a flood plain? (b) With the aid of a diagram, describe the characteristics and mode of formation of a flood plain.
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(a) A flood plain is the wide, flat land on both sides of a river in its lower course, built of alluvium deposited when the river floods.
(b) Diagram: cross-section of a river with levees and a broad flat valley floor bounded by bluffs. Characteristics: flat, low-lying land; made of fertile alluvium; found in the lower course on both banks; bounded by bluffs; often has meanders, ox-bow lakes and levees; floods in the rainy season. Formation: in the lower course the river is slow and carries much load; in the rainy season it overflows its banks; the floodwater spreads out and slows down, depositing silt over the valley floor; repeated floods build up layers of alluvium; meander migration widens the plain.
Mention deposition during floods.