rapid rivers

Question 1

watershed

Answer 1

an area of land that separates one drainage basin from another.

Question 2

source

Answer 2

the place where the river begins

Question 3

mouth

Answer 3

the place where the river begins

Question 4

tributary

Answer 4

a smaller river that connects into a bigger river

Question 5

confluence

Answer 5

the point where the tributaries connect to the main river

Question 6

erosion

Answer 6

When material is removed from the riverbed and banks.

Question 7

attrition

Answer 7

rocks carried by the river collide and break down into smaller pieces

Question 8

abrasion

Answer 8

rocks scrape against the river floor which loosen material, which is then carried away by the water.

Question 9

solution

Answer 9

soluble particles dissolve in the water.

Question 10

hydraulic action

Answer 10

the force of the river against the banks. Air becomes compressed within cracks and crevices, which weakens the banks.

Question 11

transportation

Answer 11

When material is moved further downstream.

Question 12

suspension

Answer 12

smaller material that can be continuously carried downstream.

Question 13

traction

Answer 13

large rocks are rolled downstream at times of high level.

Question 14

solution

Answer 14

very small material that can be dissolved and can be transported as a solution even at times of low level.

Question 15

saltation

Answer 15

the water picks up rocks and pebbles but are to heavy to be carried so look as though they are bouncing on the river floor.

Question 16

deposition

Answer 16

when material is dropped by the river, it is most common in the lower course where the river meets the sea. Larger, heavier material is deposited first. Smaller, lighter material can often be carried during times of low energy.

Question 17

what are the changes in a river from upper course to lower course?

Answer 17

the width and depth get bigger because of more water, there is more water in the river because water has been added from tributaries, the extra water increases the discharge and the channel takes up more space due to the space needed to fit the river.

Question 18

how are waterfalls formed?

Answer 18

The river flows over hard rock which is on top of softer rock. The soft rocks erode rapidly, the hard rock erodes slowly. As the waterfall continues to retreat over time a steep and narrow gorge is formed. The overhanging hard rock collapses into the plunge pool. This adds more hard rock into the plunge pool which continues to erode the softer rock through abrasion. As the waterfall continues to retreat over time a steep and narrow gorge is formed.