4.6

Question 1

What is meant by the long profile of the river?

Answer 1

It shows you how the gradient (steepness) changes over the different courses

Question 2

How does the river Eden’s landscape change along its long profile
(upper/middle/lower). Consider: channel shape, valley profile, gradient,
discharge, velocity and sediment size and shape?

Answer 2

Upper: v- shaped, discharge is low, narrow channel, low channel depth, low velocity, lots of sediment load size, high slope angle gradient

Middle: u-shaped, discharge is medium, wider channel, mid channel depth, higher velocity, less sediment load size, lower slope angle gradient

Lower: wide flood plain, high discharge, wide channel, deep channel, high velocity, barely any sediment size, low slope angle gradient.

Question 3

What are the reasons for river discharge changing as it goes downstream

Answer 3

More tributaries have joined, drained a much larger part of the drainage basin

Question 4

What are the reasons for channel width changing as it goes downstream

Answer 4

More discharge, tributaries have joined, velocity got quicker, more erosion power, lateral erosion

Question 5

What are the reasons for channel depth changing as it goes downstream

Answer 5

More discharge, vertical erosion, more tributaries in it, higher velocity

Question 6

What are the reasons for velocity changing as it goes downstream

Answer 6

Shape is wider and deeper, its bed and banks are smoother

Question 7

What are the reasons for sediment load size changing as it goes downstream

Answer 7

River is flowing at higher velocity, therefore higher rate of abrasion, angular beds and banks upstream too

Question 8

What are the reasons for slope angle (gradient) changing as it goes downstream

Answer 8

Upper course traction transport erodes downwards and creates vertical erosion. In lower course suspension transport is laterally eroding

Question 9

Compare hydraulic action with abrasion

Answer 9

HA : water hits banks

A : MATERIAL rubs against banks

Question 10

Define weathering

Answer 10

Weathering is the breakdown of rocks at the Earth’s surface, by the action of rainwater, extremes of temperature, and biological activity. It does not involve the removal of rock material. There are three types of weathering, physical, chemical and biological.

Question 11

Compare freeze thaw and biological weathering

Answer 11

FT: happens inside the water
BW: happens in cliff cracks but they both happen in cracks in the rock

Question 12

Compare traction with suspension transport

Answer 12

T: stones roll along bed, large sediment
S: the water flow carries silt and small particles

Different sediment sizes

Question 13

Explain the stages and processes responsible for waterfall formation

Answer 13

More resistant rock lies over less resistant rock
Less resistant rock erodes more easy by abrasion and hydraulic action.
At the foot of waterfall water swirls and erodes the bed making a plunge pool
Once resistant rock has eroded the more resistant rock collapses and this process happens lots until a gorge is formed

Question 14

Compare a flashy and subdued hydrograph

Answer 14

Flashy: high peak discharge and rainfall
Subdued: low peak discharge and rainfall

Question 15

Explain the stages and processes responsible for v shaped valleys and interlocking spurs

Answer 15

River erodes down due to gravity, less energy so no lateral erosion
Weathering occurs on the valley sides
Slope transports transports sediment off the sides to the rivers
V shaped valley is left
River weaves around bands of more resistant rocks as river is not able to erode hard rocks

Question 16

Explain the stages and processes responsible for ox-bow lakes

Answer 16

Erosion through hydraulic action and abrasion causes outside bends to get closer together
Only a bit of land between them (called a neck)
River breaks through land
River flows shortest course
Deposition cuts off meander
Forms oxbow lake

Question 17

Explain the stages and processes responsible for flood plains

Answer 17

River carries large amount of sediment
River erodes on outer bend and river migrates
Meander erodes into the hills and creates wide flat area next to river
Makes floodplain

Question 18

Explain the stages and processes responsible for levees

Answer 18

Deposition in times of river flood 
Flood spreads out and water slows down due to friction
Shingle will start the levee
Smaller sediment is deposited 
Levee is formed

Question 19

Explain the stages and processes responsible for deltas

Answer 19

River reaches sea
Loses velocity, deposits sediment faster than erosion then sediment builds up in layers in a fan shaped delta
Splits into smaller channels called distributaries
Large areas of wetland made