River Landscapes in the UK

Question 1

Erosion: Hydraulic Action

Answer 1

River bank and bed; forces air to become trapped in cracks in rocks, causing rock to break apart

Question 2

Erosion: Abrasion

Answer 2

River bed and bank, pebbles grind, sand-paper effect

Question 3

Erosion: Attrition

Answer 3

Rocks hit against each other, breaking apart to become smaller pebbles

Question 4

Erosion: Solution

Answer 4

Chemical erosion of rocks (eg, limestone and chalk), dissolving them

Question 5

Transportation: Traction

Answer 5

Large, heavy boulders rolled along river bed, load is larger, (upper course)

Question 6

Transportation: Saltation

Answer 6

Pebbles bounced along river, (middle course)

Question 7

Transportation: Suspension

Answer 7

Light sediment is suspended, (lower course)

Question 8

Transportation: Solution

Answer 8

Dissolved chemicals, soluble rocks (eg, chalk, limestone), (middle, lower course)

Question 9

Deposition

Answer 9

River loses energy, drops carried material

Question 10

Factors Leading to Deposition

Answer 10

• Shallow water
• Lower course, current speed changes (estuary)
• Inside bend of a meander (slower current)

Question 11

Drainage Basin: Area around river drained by river and its tributaries

Answer 11

Water shed — area of high land forming the edge of river basin;
Source — beginning of river;
Mouth — where river meets the sea;
Confluence — point at which two rivers meet;
Tributary — small river or stream that joins larger river;
Channel — where river flows

Question 12

River Profiles: Long Profile

Answer 12

Line representing the river from its source to its mouth, shows how river changes over its course

Question 13

Upper Course

Answer 13

Steep gradient; narrow; vertical erosion; hydraulic action; steep valley sides; abrasion and traction; waterfalls, interlocking spurs, gorges, v-shaped valley

Question 14

Middle Course

Answer 14

Decreasing gradient; wider deeper; energy increases; lateral and vertical erosion; saltation, attrition; higher discharge; meanders, oxbow lakes

Question 15

Lower Course

Answer 15

Gentle gradient; wider, deeper channel; high energy starts to slow down; lateral, vertical erosion; suspension, solution; levees, deltas, estuaries, floods

Question 16

Erosional Landforms: Waterfalls and Gorges

Answer 16

Hard rock    —> gorge
Soft rock
                Plunge pool
1. Soft rock erodes quicker than hard rock —> undercut hard rock —> overhang
2. Overhang collapses, no support
3. Abrasion and hydraulic action erode bottom —> plunge pool
4. Process repeats
5. Waterfall retreats upstream
6. Steep-sided valley left is the gorge

Question 17

Erosional Landforms: Interlocking Spurs

Answer 17

1. Vertical erosion
2. Hard rocks, hard to erode
3. River erodes around interlocking spurs

Question 18

Erosional & Depositional Landforms: Meanders

Answer 18

Slip-off …. River
slope …. Cliff
Fast current
1. Formed as water moves over shallow areas (riffles) and deep pool sections
2. More energy on outside (corkscrew motion) (hydraulic action, abrasion) —> deeper on outside bend
3. Lateral erosion undercuts outside bend —> river cliff
4. Slower current, less energy on inside bend —> deposit sediment —> slip-off slope

Question 19

Erosional & Depositional Landforms: Oxbow Lakes

Answer 19

1. Hydraulic action, abrasion erode outside bend
2. Area between the outside bend of one meander and another decreases —> ‘swan’s neck’
3. Channel cuts through meander neck when discharge is high (flood)
4. Shorter, straighter, new channel created
5. Deposition cuts off original meander, leaving horseshoe—shaped oxbow lake

Question 20

Depositional Landforms: Floodplains

Answer 20

1. Erosion removes interlocking spurs, creating wide, flat area
2. Material is carried and deposited —> height of floodplain increases
3. Fertile soil —> alluvium (deposited silt from river flood)
4. Meanders make it wide

Question 21

Depositional Landforms: Levees

Answer 21

1. During flood, water flows over banks and deposits silts —> largest material deposited first, then smaller material —> higher bank
2. In between floods, slow moving river deposits silt in riverbed
3. New river level
4. With each flood, levees are built up
5. Between floods, river bed is built up
6. River may flow well above level of floodplain

Question 22

Depositional Landforms: Estuaries

Answer 22

1. During tide rise, river water doesn’t go out to sea, so flow slows down —> silt deposited
2. When tide lowers, mudflats exposed, become salt marshes —> important habitat for wildlife

Question 23

Depositional Landforms: Deltas

Answer 23

Sediment deposited before sea can remove it at the mouth —> forms little areas of land with smaller channels —> tributaries

Question 24

Causes of Flooding: Prolonged Rainfall

Answer 24

Soil around river becomes saturated —> more surface run-off into river

Question 25

Causes of Flooding: Heavy Rainfall

Answer 25

Less infiltration of soil —> surface run-off in river

Question 26

Causes of Flooding: Relief

Answer 26

Steep valley —> more surface run-off into river; water runs too fast for being absorbed and infiltrate soil

Question 27

Causes of Flooding: Geology

Answer 27

Permeable rocks allow water to infiltrate; | Impermeable rocks —> more surface run-off into river

Question 28

Causes of Flooding: Vegetation

Answer 28

Trees and plants intercept water, deforestation increases surface run-off and flood risk

Question 29

Causes of Flooding: Urban Land Use

Answer 29

Tarmac and concrete are impermeable, increasing surface run-off and no infiltration or absorption of water

Question 30

Hydrograph Info

Answer 30

Peak discharge — maximum volume of water held in channel; Peak rainfall — maximum amount of rainfall (mm); Lag time — time taken between peak rainfall and peak discharge; Rising limb — shows increase in discharge; Falling limb — shows return of discharge to normal/base flow; Base flow — normal discharge of river

Question 31

Factors Influencing Lag Time (Hydrograph)

Answer 31

- Size of drainage basin — large = high p.d., long lag time (v.v.) - Vegetation — bare = short lag time, high p.d. (v.v.) - Valley side steepness — steep = short lag time, high p.d. (v.v.) - Soil type — impermeable = short lag time, high p.d. (v.v.)

Question 32

Hard Engineering

Answer 32

Involved building artificial structures which try to control rivers. They tend to be more expensive.

Question 33

Hard Engineering: Dams and Reservoirs

Answer 33

+ Produce electricity; + Attract tourists; - Expensive; - Dams trap sediment which decreases water capacity; - Habitats flooded —> rotting vegetation —> releases methane (greenhouse gas); - Settlements lost —> displacing people (in developing countries, people often don’t have a say or are consulted)

Question 34

Hard Engineering: River Straightening and Dredging

Answer 34

+ More water held in channel; + Reduce flood risk in built-up areas; - Dredging needs to be done frequently; - Speeding up river increases flood risk downstream

Question 35

Hard Engineering: Embankments

Answer 35

+ Cheap + Allows for flood water to be contained within river - Looks unnatural - Water speeds up, increase flood risk downstream

Question 36

Hard Engineering: Flood Relief Channels

Answer 36

+ Removes excess water from river channel to reduce flooding; - Expensive - Relief channel may also flood due to continuous rising water levels —> other areas flooded instead

Question 37

Soft Engineering

Answer 37

Involves a natural approach to managing river flooding with no artificial structures

Question 38

Soft Engineering: Flood Warnings and Preparation

Answer 38

+ People have time to protect their properties (eg, with sandbags); + Many possessions can be saved, resulting in fewer insurance claims; - Not everyone may be able to access the warnings; - Flash floods may happen to quickly for a warning to be effective; - They do not stop flooding, just warn people

Question 39

Soft Engineering: Floodplain Zoning

Answer 39

+ More expensive buildings and land uses are farther away, so reduced flood risk; + Less damage caused —> fewer insurance claims; - Not always possible to change existing land uses; - Planners have to decide wha type of flood to plan for

Question 40

Soft Engineering: Planting Trees (Afforestation)

Answer 40

+ Intercepts water; + Less surface run-off; - Loss of potential grazing land; - May look artificial

Question 41

Soft Engineering: River Restoration

Answer 41

``` + New animal habitats; + Attractive —> boosts tourism; + Reduces flooding downstream; - Loss of potential grazing land; - Expensive; - Not always practical or effective ```

Question 42

Soft Engineering: Earthen Embankments

Answer 42

``` + Provide habitats; + Attractive walkways; + Increased river capacity: + Cheap; - Prone to erosion; - High maintenance cost; - Give sense of false security ```