River Landscapes in the UK

Question 1

What is a river’s path called?

What does the long profile of a river show?

What does the cross profile of a river show?

Answer 1

Course

How the gradient changes

The cross-section of the river

Question 2

Describe the upper course of a river

Answer 2

Steep, v-shaped valley, narrow, shallow channel

Question 3

Describe the middle course of a river

Answer 3

medium gradient, gently-sloping valley, wider, deeper channel

Question 4

Describe the lower course of a river

Answer 4

gentle gradient, almost flat valley, very wide, deep channel

Question 5

Name and define the four erosion processes

Answer 5

Hydraulic action - force of the water colliding with rocks
Abrasion - rocks picked up by the river scrape against the channel
Attrition - rocks picked up by the river bang into each other, becoming smaller and rounder
Solution - river water dissolves some types of rock

Question 6

Name and define the four transportation processes

Answer 6

Traction - large particles (boulders) are pushed along the river bed
Suspension - small particles are carried by the water
Saltation - pebble-sized particles ‘bounce’ along the river bed
Solution - soluble materials dissolve and are carried along

Question 7

Where in the river course do waterfalls form?

What process causes waterfalls to form?

What type of rock formation is needed for a waterfall to form?

Answer 7

Upper course

Erosion

Hard rock on top of soft rock

Question 8

How is a waterfall formed?

Answer 8

River flows from hard rock onto soft rock
Soft rock is eroded quickly - creates a drop
Water falls into a turbulent plunge pool
Abrasion/ hydraulic action erodes the soft rock underneath, creates an overhang of hard rock
The hard rock is undercut, making it collapse
The waterfall retreats - the process repeats

Question 9

How is a gorge formed?

Answer 9

When a waterfall retreats, it leaves behind a narrow, steep-sided valley (a gorge)

Question 10

Where in the river course are interlocking spurs found?

What process causes interlocking spurs to form?

Answer 10

Upper course

Erosion

Question 11

How are interlocking spurs formed?

Answer 11

In the upper course, erosion is vertically downwards
River lacks power to erode laterally
So it has to wind against the hillsides in its path
This makes a winding river in between interlocking hills

Question 12

Where in the river course are meanders found?

What process causes meanders to form?

What is a meander?

Answer 12

Middle course

(lateral) Erosion and deposition

A bend in a river

Question 13

How are meanders formed?

Answer 13

Current is faster on the outside of the bend (river channel is deeper = less friction) = more erosion
Helicoidal flow (corkscrew motion) moves material from the outside of one bend to the inside of another
Current is slower on the inside (river channel is shallower = more friction) = more deposition

Question 14

Compare the inside of a meander bend to the outside

Answer 14

Inside:
deposition, slower flow, shallow, river beach/ slip-off slope

Outside:
erosion, fastest flow, deeper, river cliff (caused by erosion from helicoidal flow)

Question 15

How is an ox-bow lake formed?

Answer 15

Meanders get larger over time - erosion causes the outside bends of two meanders to get closer
Eventually, the river breaks through the neck of the meander
River flows through the shortest course
Deposition cuts off the meander = ox-bow lake

Question 16

What is a flood-plain?

Where in the river course are flood plains found?

What process causes flood plains to form?

Answer 16

The wide valley floor on either side of a river that occasionally floods

Lower course

Deposition

Question 17

How are flood-plains built up over time?

Answer 17

When rivers flood, the water slows down, loses energy and deposits the material it was transporting
The deposition that happens on slip-off slopes of meanders also build it up

Question 18

Where in the river course are levees found?

What process causes levees to form?

What are levees?

Answer 18

Lower course

Deposition

Natural embankments (raised banks) on the edges of a river channel

Question 19

Where are estuaries found?

What is the land like in an estuary?

What is the water like in an estuary?

Answer 19

At river mouths (lower course)

Close to sea level, rive valley is at its widest

Tidal

Question 20

How are estuaries / mudflats formed?

Answer 20

When water floods the banks, it carries silt/sand onto the valley floor
When the tide is highest, it has little energy, deposits sediment
Over time, mud builds up, making mudflats
Mudflats are exposed at low tide

Question 21

Where is the River Tees located?

Where is its source?

Where is its mouth?

Answer 21

North east England

Pennines

North Sea at Middlesborough

Question 22

What is the land use in the upper course of the Tees?

What is an example of a landform in the upper course?

What rock types is it made from?

Answer 22

Reservoirs, farming

High Force waterfall

Hard rock = whinstone, soft rock = limestone

Question 23

What is the land use in the middle course of the Tees?

What is the shape of the valley here?

Answer 23

Farming (95%)

U-shaped

Question 24

What is the land use in the lower course of the Tees?

Answer 24

a town, nuclear plant, iron/steel works

Question 25

What is river discharge?

Answer 25

The volume of water flowing per second, measured in cumecs (cubic metres per second)

Question 26

What does a hydrograph show?

Answer 26

The river discharge after a period of heavy rainfall

Question 27

On a hydrograph, what is: Peak discharge Lag time Rising limb Falling limb

Answer 27

Highest discharge on the hydrograph The delay between peak rainfall and peak discharge The increase in river discharge The decrease in river discharge

Question 28

What factors decrease (flash flood) / increase (slow onset flood) lag time?

Answer 28

Decrease: - steep gradient of drainage basin - impermeable rocks (more surface runoff) - impermeable man made surfaces (" ") - saturated soil (" ") - small drainage basin - areas without vegetation (less interception) - heavy rain (rapid saturation of soil = more surface runoff)

Question 29

What is hard engineering?

Answer 29

Man-made structures that control the flow of rivers to reduce flooding

Question 30

What is soft engineering?

Answer 30

Schemes set up using knowledge of a river to reduce the effects of flooding

Question 31

Explain some examples of hard engineering to reduce flooding.

Answer 31

- Dams / Reservoirs - reservoirs control water flow + HEP produced, BUT expensive, reservoirs flood - Channel straightening - meanders removed, water leaves area quickly, BUT floods happen downstream - Embankments - river can hold more water BUT expensive, severe flooding if they break - Flood relief channels - divert excess water, gates control flow of water BUT increased discharge where relief channel re-joins the river

Question 32

Explain some examples of soft engineering to reduce flooding.

Answer 32

- Warnings/Preparation - buildings modified, people can prepare BUT no prevention/protection, modifying buildings expensive - Flood plain zoning - restrictions prevent building here, flood risk reduced BUT urban expansion limited - Planting trees - increase interception, provides habitats BUT less land for farming - River restoration - lets the flood-plain flood, little maintenance BUT local flood risk increases

Question 33

In a named example, what were some flood defences?

Answer 33

Boscastle: - wider bridge span (more water can flow under) - lower river bed / widen channel (increase capacity) - remove dead trees/add trash screens (stops river getting clogged)