✅rivers

Question 1

what physical factors affect flood

Answer 1

heavy rainfall —> water arrives too quickly for it to infiltrate so there’s a lot of surface run off which increases discharge

geology (rock type) —> some are impermeable e.g. granite so run off is increased

prolonged rainfall —> saturate soil so rain can’t infiltrate —> runoff into river channels

relief —> water will reach river channel quicker because it can flow down faster —> increases discharge

Question 2

what are the human factors of flooding

Answer 2

land use e.g. agriculture, deforestation and urbanisation

buildings made from impermeable materials —> increasing surface run off —> increasing discharge

trees intercept rain and take it in to store water —> cutting it down increases water that enters the river channel

Question 3

hard engineering

Answer 3

man made structures built to control flow of rivers and reduce flooding

Question 4

how to reduce flooding using hard engineering

Answer 4

dams and reservoirs

channel straightening

embankments

flood relief channels

Question 5

what are dams and reservoirs

Answer 5

dams- barriers built across rivers

reservoir- artificial lake formed behind dam

Question 6

benefits of dams and reservoirs

Answer 6

store water and prevent floods downstream

used to generate hydroelectric power (HEP)

Question 7

disadvantages of dams and reservoirs

Answer 7

expensive to build dams

reservoir can flood existing settlements

material is deposited in reservoir so farmland downstream can become less fertile

Question 8

what is channel straightening

Answer 8

meanders are removed by building straighter artificial channels

Question 9

adv of channel straightening

Answer 9

water is moved out of an area quickly —> reduces flood risk

Question 10

disadvantages of channel straightening

Answer 10

flooding may happen downstream instead

faster moving water may cause more erosion downstream

Question 11

what are embankments

Answer 11

raised walls are built along river banks

Question 12

adv of embankments

Answer 12

river can hold more water so floods less frequent

Question 13

disadvantages of embankments

Answer 13

expensive and risk of flooding so many break

Question 14

what are flood relief channels

Answer 14

channels built to divert water around built up areas or divert excess water if river level gets too high

Question 15

adv of flood relief channels

Answer 15

gates on channels mean that release of water can be controlled reducing flood risk

Question 16

disadvantages of flood relief channels

Answer 16

increased discharge where relief channel rejoins the river which could cause flooding in that area

Question 17

what is soft engineering

Answer 17

schemes set up using knowledge of a river and its processes to reduce the effects of flooding

Question 18

what is flood warnings and preparation

Answer 18

environment agency issues flood warnings through various media (e.g. TV, radio, internet)

buildings are modified to minimise flood damage

residents can prepare sandbags and flood boards prior to floods

Question 19

advantages of flood warnings and preparation

Answer 19

warnings give ppl time to move possessions upstairs, put sandbags in place or evacuate —> reduces the impact of flooding

Question 20

disadvantages of flood warnings and preparation

Answer 20

warnings don’t prevent floods

people may not have access to the warnings

modifying buildings is expensive

Question 21

what is flood plain zoning

Answer 21

restrictions that prevent land use on parts of a flood plain that are likely to be affected by a flood

Question 22

adv of flood plain zoning

Answer 22

flood risk is reduced —> fewer impermeable surfaces are created (e.g. roads)

impact of flooding is reduced - no buildings to damage

Question 23

disadvantages of flood plain zoning

Answer 23

expansion of an urban area is limited if there aren’t any other suitable building sites

can’t help in areas with existing buildings

Question 24

what is planting trees

Answer 24

planting trees increases the interception of rainwater

Question 25

advantages of planting trees

Answer 25

discharge and flood risk decrease

vegetation reduces soil erosion and provides habitat for wildlife

Question 26

disadvantages of planting trees

Answer 26

less land available for farming

Question 27

what is river restoration

Answer 27

making river more natural by removing man made structures so flood plain can flood naturally

Question 28

advantages of river restoration

Answer 28

discharge is reduced —> less risk of flooding downstream

little maintenance is needed and better habitats for wildlife

Question 29

disadvantages of river restoration

Answer 29

local flood risk can increase especially if nothing is done to prevent major flooding

Question 30

why does leeds need a flood management scheme

Answer 30

leeds is located on the floodplain of the river aire

this is a tributary of the river ouse which eventually joins the humber estuary near hull

Question 31

what was the issue in leeds

Answer 31

on boxing day in 2015, storm eva caused flooding in leeds

environnement agency issued a red warning

Question 32

how high is the river aire normally and what did it rise to

Answer 32

river aire- 0.9 metres and rose to 2.95m at 1am on the 27th december —> affected the city centre and kirkstall road area

Question 33

what were the effects of the flood

Answer 33

damage to leeds was £36.8m

3355 properties were damaged (672 being businesses)

Question 34

what has been done to reduce flooding in leeds

Answer 34

1. moveable weirs at crown point in the city centre and further downstream at knostrop (can be lowered to create more room for flood water)
2. merging river and canal (removal of 600m stretch of land known as knostrop cut island allowed river and canal to merge) (additional flood capacity for flood water)
3. flood walls, glazed panels and embankments stretching more than 4.5km
   (raise capacity in times of flood)

Question 35

social impacts of the river aire management

Answer 35

+ quality of life improved for people with new green areas

+ reduced levels of anxiety as reduced flood risk

Question 36

economic impacts of the river management scheme (positive and negative)

Answer 36

+ main routes will remain open in flood, reducing disruption for people

+ there are financial benefits by protecting houses and businesses

• cost of the scheme is about £50 million so far and expected to be nearer £100 million when fully completed

Question 37

environmental impacts of river management scheme

Answer 37

+ moveable weir helps nature —> less flooding so organisms are protected

+ thousands of new trees help the environment through natural flood management

• part of the floodplain will be allowed to deliberately flood in designated areas if river levels are high —> reduce biodiversity

Question 38

how is a levée formed

Answer 38

1. sediment upstream is transported downstream
2. when a river floods, the sediment spreads across the floodplain
3. largest material is deposited first on the sides of the river bank and the smaller material is deposited further away
4. after many floods, the sediment builds up to increase the height of embankments so it can carry more water which reduces flooding

Question 39

cross section

Answer 39

shape of the river valley

Question 40

long profile

Answer 40

shape of the gradient