Rivers

Question 1

Define transportation.

Answer 1

the load (mud, rocks, etc) that have been eroded by a river and are carried downstream.

Question 2

Define deposition.

Answer 2

River dopping eroded material on the river bed when it can’t carry it anymore.

Question 3

Define corrasion (abrasion).

Answer 3

sand and pebbles are dragged along the riverbed, wearing it away.

Question 4

Define hydraulic action.

Answer 4

fast-flowing water is forced in cracks, breaking up the bank over time.

Question 5

Define attrition.

Answer 5

rocks and stones wear each other away as they knock together, becoming smaller and rounder.

Question 6

Define solution.

Answer 6

rocks such as limestone are dissolved in acid rainwater.

Question 7

Define saltation.

Answer 7

smaller stones/pebbles are picked up and then dropped again.

Question 8

Define traction.

Answer 8

large stones are dragged along.

Question 9

Define bedload.

Answer 9

heavier material is carried along the bottom.

Question 10

Define suspension.

Answer 10

tiny particles of sediment are carried in the river’s current.

Question 11

What are the three factors affecting the work carried out by a river?

Answer 11

• Velocity of the running water
• Volume of running water
• Bedrock along the course of a river

Question 12

Define discharge.

Answer 12

volume of water flowing down the river at any one time. measured in cubic meters per second.

Question 13

What are the three river channel types?

Answer 13

1) meandering
2) straight
3) braided

Question 14

What is the source?

Answer 14

the place where the river starts.

Question 15

What are potholes?

Answer 15

smooth, rounded hollows in the bedrock of the river bed caused by vertical erosion. formed by stones trapped in hollows.

Question 16

Where do rapids form?

Answer 16

where water is shallow and riverbed is rocky and irregular.

Question 17

Where do waterfalls and gorges form?

Answer 17

Where hard rock is on top of soft rock in a river. Soft rock erodes quickly and develops into a plunge pool. Splashing water and eddy currents in pluge pool undercut hard rock later until it creates an unsupported overhang and collapes. This process repeates for centuries as the waterfall retreats upstream and a gorge is created.

Question 18

Define levee.

Answer 18

natural embankment on sides of rivers created by deposition.

Question 19

Define flood plain.

Answer 19

flat area next to river liable to flooding.

Question 20

Define delta.

Answer 20

flat area where river meets sea/lake.

Question 21

Define distributary.

Answer 21

smaller channels of the river that form a braided pattern.

Question 22

What is an oxbow lake?

Answer 22

a meander that has been cut off from the river.

Question 23

Where are deposition and erosion on a meandering river?

Answer 23

deposition on inside of river and erosion on outside.

Question 24

Define drainage basin.

Answer 24

an area of land that catches rain and snow, and drains into a common body of water.

Question 25

Define watershed.

Answer 25

an imaginary line between two drainage basins that separates basins from each other. they are usually along the ridges of mountains.

Question 26

What are four benefits of rivers and river flood plains?

Answer 26

1. flat land for roads, buildings, and agriculture
2. mineral-rich and fertile soils
3. river valleys are natural route-ways
4. rivers provide transportation routes, water, and fish

Question 27

What are two problems caused by rivers and flood plains?

Answer 27

1. Disease carried by insect pests
2. Liable to flooding

Question 28

What are the five factors affecting discharge?

Answer 28

• rainfall
• relief
• land use
• weather conditions
• rock and soil type

Question 29

What is antecedent rainfall?

Answer 29

rain that’s already happened so the ground is saturated and more rain will flow as surface run-off towards river.

Question 30

What are five methods of flood prevention and defences?

Answer 30

1) planting vegetation
2) reservoirs
3) straightening the channel
4) dredging the channel
5) artificial levees