RIVERS

Question 1

DRAINAGE BASIN DIFFERS FROM A HYDROLOGICAL CYCLE

Answer 1

• drainage basin: open system ( amount of water varies )

- hydrological cycle: closed system ( always same water )

Question 2

INPUTS DRAINAGE BASIN

Answer 2

• energy from the sun
• precipitation formed from moisture picked up outside the basin
• possibly water from tributary drainage basis

Question 3

OUTPUTS DRAINAGE BASIN

Answer 3

• the rivers discharge
• the water in its basin from which evaporation and transpiration take place ( this water eventually falls as precipitation in another drainage basin )

Question 4

STORM HYDROGRAPHS

Answer 4

• record the changing discharge of a river after a rainstorm
• base flow: normal discharge
• storm flow: additional discharge

Question 5

RIVER REGIMES

Answer 5

• river discharges vary throughout the year

- these variations make up what is termed the river regime

Question 6

FACTORS AFFECTING RIVER REGIMES

Answer 6

• amount and intensity of the rain
• temperatures affect the form of precipitation
• steep slopes will cause rapid surface run off, so water will reach the river more quickly
• rock type ( permeable or impermeable )
• vegetation and land use
• human intervention

Question 7

ROCK TYPE

Answer 7

• impermeable rocks will not allow rainwater to sink into it, so will speed up run off
• permeable rocks allow infiltration and percolation of water into the bedrock ( slows delivery of water to the river )

Question 8

VEGETATION AND LAND USE

Answer 8

• trees and other plants intercept and delay the rain reaching the ground

Question 9

HUMAN INTERVENTION

Answer 9

• dams and reservoirs are an obvious form of intervention in river regimes

Question 10

FLUVIAL PROCESSES

Answer 10

( rivers -> shaping landforms )

• erosion
• transport
• deposition
• weathering
• mass movement

Question 11

EROSION HYDRAULIC ACTION

Answer 11

• water hits the river bed and banks with such force that material is dislodged and carried away ( high discharge )

Question 12

EROSION ABRASION

Answer 12

• material being carried by a river is rubbed against the sides and floor of the channel

Question 13

EROSION CORROSION ( SOLUTION )

Answer 13

• minerals in the rocks forming the sides of the river channel are dissolved by the water flowing past them

Question 14

EROSION ATTRITION

Answer 14

• particles of materials being carried by a river = become rounded and smaller as they collide between

Question 15

PHYSICAL WEATHERING

Answer 15

• this breaks rocks down into smaller and smaller pieces

Question 16

CHEMICAL WEATHERING

Answer 16

• this causes rocks to decay and disintegrate ( acidic rain seeping into porous rocks )

Question 17

BIOLOGICAL WEATHERING

Answer 17

• roots of plants ( especially trees ) growing into cracks in the rocks gradually split the rock apart

Question 18

TRANSPORT

Answer 18

• traction
• saltation
• suspension
• solution

Question 19

TRANSPORT TRACTION

Answer 19

• large boulders rolled on the bed

Question 20

TRANSPORT SALTATION

Answer 20

• small boulders bounced along the bed

Question 21

TRANSPORT SUSPENSION

Answer 21

• lighter material carried along by the river flow

Question 22

TRANSPORT SOLUTION

Answer 22

• material dissolved in the water

Question 23

DEPOSITION

Answer 23

• deposition is the laying down of material transported by the river
• occurs when there is a decrease in:
  
  1. energy
  2. speed
  3. discharge
     … of the river
• likely to happen when a river enters a lake or the sea

Question 24

FACTORS AFFECTING EROSION, TRANSPORT AND DEPOSITION

Answer 24

1. wetter climate
2. soften rocks
3. gentle slopes

Question 25

WETTER CLIMATE

Answer 25

• more discharge

- more erosion and transport

Question 26

SOFTEN ROCKS

Answer 26

• more easily eroded and transported

Question 27

GENTLE SLOPES

Answer 27

• encourage deposition

Question 28

CHANNEL CHARACTERISTICS

Answer 28

UPSTREAM DOWNSTREAM
load particle size
-> channel bed roughness
-> slope angle ( gradient )