Depositional River Landforms

Question 1

Define flood plain

Answer 1

They are flat areas of land that flood. It is the wide valley floor on either side of a river that flood. When a river floods onto a flood plain, the water slows down and deposits eroded material. This builds up the flood plain.

Question 2

Define levees

Answer 2

They are natural embankments along the edges of a river

Question 3

How do levees form?

Answer 3

After many floods, the sediment builds up to increase the height of the river banks, meaning that the channel can carry more water (a greater discharge) and flooding is less likely to occur in the future.

Question 4

Where does the heaviest and lightest material in a levee go?

Answer 4

The heaviest material gets deposited closest to the river channel as its gets dropped first. Meanwhile the lightest material gets dropped last so its at the end of an embankment.

Question 5

Define Delta

Answer 5

They are low-lying areas where a river meets the sea or lake.
Delta is a low triangular area of alluvial deposits where a river divides

Question 6

Explain formation of a delta

Answer 6

1. )Rivers slows down when they meet a sea as the gradient becomes shallower. This causes them to deposit the material the material that they are carrying.
2. ) If the sea does not wash away the material it builds up and the channel gets blocked, forcing the channel to split up into smaller rivers called distributaries
3. ) Eventually the material builds up so much that low lying area of land called deltas formed

Question 7

Define tributary

Answer 7

River or stream that flows INTO a larger stream or main river

Question 8

Define distributary

Answer 8

River or stream that branches away and flows OUT of a main stream.

Question 9

Name the three types of deltas

Answer 9

Arcuate, Cuspate and Bird’s foot

Question 10

Define Arcuate

Answer 10

A delta that has a rounded shaped and has a lot of distributaries

Question 11

Define Cuspate

Answer 11

A delta that has a triangular shape and has a few distributaries

Question 12

Define Bird’s foot

Answer 12

A delta that is shaped like a bird’s foot with a section of low lying land sticking out to the side

Question 13

Through which two process do flood plains form?

Answer 13

Deposition and Erosion

Question 14

Explain formation of flood plain in terms of erosion

Answer 14

Erosion removes any interlocking spurs, creating a wide, flat area on either side of the river

Question 15

Explain formation of flood plain in terms of deposition

Answer 15

During a flood, material being carried by the river is deposited (as the river loses its speed and energy to transport material). Over time, the height of the floodplain increases as material is deposited on either side of the river.

Question 16

What type of material do rivers deposit to make flood plains?

Answer 16

Its made up alluvium which is a type of sediment.

Question 17

what are flood plains often used for?

Answer 17

Agricultural Land due to its fertility

Question 18

What course do levees, deltas, mudflats and flood plains form ?

Answer 18

The lower course

Question 19

Define estuary

Answer 19

The open mouth of a river where the river meets the sea. The river here is tidal and when the sea retreats the volume of the water in the estuary is less reduced. When there is less water, the river deposits silt to form MUDFLATS which are an important habitat for wildlife.

Question 20

Define mudflats

Answer 20

sheltered coastal areas where mud is deposited by tides or rivers.