Rivers- River Channel

Question 1

Hydraulic radius

Answer 1

Cross sectional area divided by wetted perimeter

Question 2

Hydraulic action

Answer 2

Movement of sediment by the frictional drag of the moving water

Question 3

Abrasion

Answer 3

Rubbing or scouring of the bed and banks by the sedimentary material carried along by the river

Question 4

Attrition

Answer 4

Reduction in size of the sediment particles as they collide with each other, the bed and the banks

Question 5

Corrosion

Answer 5

Where rocks dissolve into the water and are carried away

Question 6

Bed load - traction

Answer 6

Boulders/ cobbles too heavy to be picked up by the current roll/ slide along the channel floor

Question 7

Bed load - saltation

Answer 7

Pebbles/ sand grains get temporarily lifted and bounced along floor in a hopping motion

Question 8

Suspended load - suspension

Answer 8

Bulk of sediment transportation. Fine muds and clays up to grains of sand are carried in the flowing water. Water is muddy colour towards mouth.

Question 9

Dissolved load - solution

Answer 9

Solution is so small it has become dissolved in the water. Most common where rivers run through areas of carbonate rocks. Weak acids may act on more soluble rocks and remove material in solution

Question 10

Wetted perimeter

Answer 10

The portion of the perimeter of a stream cross section that is in contact with the water