Levées, Flood Plains & Estuaries Flashcards

All 6 cards in this deck

What is a levée?

A long, raised ridge or embankment of sediment along the river banks, higher than the flood plain and steeper on the channel side.

When a river floods, which material is deposited closest to the channel?

The largest, heaviest material (sand and gravel); finer silt and mud is carried further across the flood plain.

What is a flood plain?

The wide, flat area of land either side of a river that is covered in water when the river floods, built up by deposited sediment.

What is an estuary?

The wide, shallow river mouth where the river meets the sea, with mudflats and salt marshes formed from deposited silt and mud.

How do meanders help to widen a flood plain?

Meanders migrate across the valley, and lateral erosion on their outer bends cuts away the valley sides, so the flat valley floor gets wider.

How do mudflats form in an estuary?

As the tide comes in, river water is held back and slows, so it deposits silt. Over time this builds up mudflats that are uncovered at low tide.