Physical Landscapes: Rivers

Question 1

How does the river valley change as the river moves from the upper course to the lower course?

Answer 1

valley becomes wider and deeper

Question 2

How does relief contribute to flooding?

Answer 2

steep slopes allow for water to run over the land quickly - less time for water to seep into the soil, more water entering river channel

Question 3

How does precipitation contribute to flooding?

Answer 3

torrential rainstorms can lead to flash flooding

Question 4

How does rock type contribute to flooding?

Answer 4

impermeable rocks does not allow infiltration of water (e.g. clay) - more water flowing to river

Question 5

How does urbanisation contribute to flooding?

Answer 5

impermeable rock (tarmac) means water drains into river channel

Question 6

What is lag time?

Answer 6

number of hours between peak rainfall and peak discharge

Question 7

What is meant by the term ‘hard engineering’?

Answer 7

use of man-made structures to control the flow of a river and prevent flooding or erosion

Question 8

What is meant by the term ‘soft engineering’?

Answer 8

managing a river using natural materials and mimicking natural processes to protect more vulnerable areas

Question 9

4 hard engineering strategies

Answer 9

-channel straightening
-embankments
-dams + reservoirs
-flood relief channel

Question 10

4 soft engineering strategies

Answer 10

-flood plain zoning
-flood warnings + preparation
-afforestation
-river restoration

Question 11

How does flood plain zoning reduce flood risk?

Answer 11

-low quality land on flood plains
-e.g. sport pitches, car parks, livestock farming

Question 12

How does afforestation reduce flood risk?

Answer 12

-intercepts water
-slows down water in drainage basin

Question 13

Where does the Jubilee River flood-relief channel flow?

Answer 13

flows from West to East, through Greater London

Question 14

What 2 areas does the Jubilee River flood-relief channel flow through?

Answer 14

-Windsor
-Wraysbury

Question 15

How much did the relief channel cost?

Answer 15

£110million (most expensive flood-relief scheme in UK)

Question 16

How long is the relief channel?

Answer 16

11.7km

Question 17

How much does it cost to repair the relief channel after flooding?

Answer 17

£680,000

Question 18

How many homes have been protected due to the relief channel?

Answer 18

3200 homes

Question 19

What happened in 2014 in the River Thames?

Answer 19

-worst flood since 1947
-river’s discharge is much higher due to relief channel

Question 20

How wide was the relief channel?

Answer 20

50m

Question 21

How does a flood relief channel reduce flooding?

Answer 21

increases channel capacity/ volume

Question 22

How do embankments reduce flooding?

Answer 22

raising river banks - higher volume of water can be contained in the river

Question 23

How are interlocking spurs formed?

Answer 23

-vertical erosion: cuts in landscape at angles
-lack of lateral erosion causes river to wind around hillsides

Question 24

2 characteristics of interlocking spurs

Answer 24

-steep-sided hills
-river winds round hills

Question 25

2 characteristics of gorges

Answer 25

-steep sides
-upstream retreat of waterfall

Question 26

How is a waterfall formed?

Answer 26

-hydraulic action breaks down soft rock
-soft rock undercuts hard rock
-rock collapses into river bed
-abrasion creates plunge pool

Question 27

How are meanders formed?

Answer 27

-river erodes river bank, creating bend
-water swings to outside of river (less friction)
-slower flow on inside of bend (deposits materials)

Question 28

How is an oxbow lake formed?

Answer 28

-meander’s river neck grows narrower
-when neck breaks through, river takes shortest route on straight course

Question 29

2 characteristics of a levees

Answer 29

-raised bank on side of river
-coarser sediment nearest river edge

Question 30

2 characteristics of a floodplain

Answer 30

-flat land
-side of river