Rivers - Floods

Question 1

Flooding

Answer 1

where land that is normally not underwater becomes submerged

Question 2

infiltration

Answer 2

Water sinking into the soil from the ground surface

Question 3

discharge

Answer 3

amount of water than passes a given point on a stream or river bank within a given period of time

Question 4

interception

Answer 4

water prevented from reaching the surface by trees and grass

Question 5

physical causes

precipitation

Answer 5

• continuous heavy rainfall + prolonged light rainfall - saturates the soil (aka fills pores w/ water)
• sudden bursts/snow - (snow melts), infiltrates quickly, surface runoff increases, water will reach river quicker so the discharge increases

Question 6

physical causes

geology

Answer 6

• impermeable rock - doesnt allow water to infiltrate = more surface runoff = increase in discharge
• permeable rock - allows water to infiltrate, so waters store = decrease chance of flood

Question 7

physical causes

relief

Answer 7

• steep slopes - more likely for surface runoff bc water doesnt have time to infiltrate bc its going down = higher discharge
• flat + flood plains - lower risk bc water has time to infiltrate the soil

Question 8

human causes

urban land use

Answer 8

• new infrastructure/new housing/disappearing gardens: increases area covered by impermeable surfaces = more surface runoff
• new housing: rainwater will flow into gutters and into drains, can be built in place w/ high flood risk

Question 9

human causes

rural land use

Answer 9

• deforestation: reduces interception = saturated soil = increased runoff = increased discharge
• farming technique: removal of hedges, arable results in soil being bare
• urbanisation: greenfield sites getting built on
• climate change: extreme weather events, increased temp = more evap = more rainfall

Question 10

effects

social

Answer 10

• Injury
• Death
• Loss of home
• Loss of belongings
• Damage to property
• Stressful
• Isolate – loss of roads
• Loss of recreational facilities

Question 11

effects

economic

Answer 11

• Rebuild/fixing damage
• High insurance claims
• Loss of work/employment
• Loss of revenue for local area
• House value could decline

Question 12

effects

enviornmental

Answer 12

• Habitats lost
• Loss of land
• Disrupts breeding areas
• Spread of pollution
• Spread of disease
• Large deposits of mud left behind
• Unsanitary conditions if sewage/grains flood

Question 13

Flashy Response

Answer 13

when a drainage basin responds quickly

Question 14

flashy hydrogaphy

basin size

Answer 14

small basins often lead to rapid water transfer

Question 15

flashy hydrogaphy

drainage density

Answer 15

high density speeds up water transfer

Question 16

flashy hydrographs

rock type

Answer 16

impermeable rocks helprapid overland flow

Question 17

flashy hydrogaphy

land use

Answer 17

urbanisation = rapid water transfer

Question 18

flashy hydrogaphy

relief

Answer 18

steep slopes = rapid water transfer

Question 19

flashy hydrogaphy

soil moisture

Answer 19

saturated soil= rapid overland flow

Question 20

flashy hydrogaphy

rainfall intensity

Answer 20

heavy rain may be more than vol that can be intercepted = rapid overland flow

Question 21

flat hydrograph

basin size

Answer 21

large basin = slow water transfer

Question 22

flat hydrograph

drainage density

Answer 22

low density = slow water transfer

Question 23

flat hydrograph

rock type

Answer 23

permeable rock = slow water transfer bc it mves in groundwater flow

Question 24

flat hydrograph

land use

Answer 24

forest = slower water transfer bc interception

Question 25

flat hydrograph

relief

Answer 25

gentle slopes = slower water transfer

Question 26

flat hydrograph

soil moisture

Answer 26

dry soil =slower water transfer

Question 27

flat hydrograph

rainfall intensity

Answer 27

light rain = slower transfer

Question 28

hard engineering

embankents

Answer 28

advantages
* cheap compared to hard engineering
* channel has more space
* used for riverside footpaths
* provide habitats for animals eg kingfishers and otters
disadvantages
* high maintance cost
* no easy access for boats and fishing
* false sense of security = not being prepped for floods
* concrete lining displaces animals
* ugly
* breached water cant get back into the river = water lying on ground for a while

Question 29

hard engineering

flood relief channel

Answer 29

advantages
* artificial reed beds and grass-covered concrete sides = provide new habitats
* no flooding in a particular area
* footpaths & cycle tracks are built along channel, bird watching and nature reserves
* lower insurance costs
* value of homes increases = easier
disadvantages
* habitats disturbed
* ugly
* expensive + high maintance
* displacment
* some ppl protected at the expense of others

Question 30

hard engineering

dams & reservoirs

Answer 30

advantages
* boosts tourism
* hydroelectric power
* area around used by forestry to plant trees = employment
* drinking water
* no flood risk
* new habitats
disadvantages
* relocation of ppl
* communities break up
* v expensive to build and mantain
* less fertile soil = less yield bc of lack of sediment deposited downstream
* algae builds up = deoxyginated water
* may trigger earthquakes/landslides
* floods areas of outstanding natural beauty = kills plants and animals

Question 31

hard engineering

channel straightening

Answer 31

advantages
* protects places from flooding
* may prevent nesting sites from being lost
* moves water away more quickly = reduced flood risk
* straight course improves navig & increases trade opportuns
* insurance cost goes down = homeowners more likely to invest
disadvantages
* v expensive
* ugly
* problem not solved just moved away
* downstream floods effects animals
* fast flow in straight sections = deposition of silt elsewhere = floods

Question 32

hard engineering

Answer 32

use of artificial structures to prevent or control natural processes

Question 33

soft engineering

Answer 33

work with natural river processes to manage the flood risk

Question 34

soft engineering

flood warning and prep

Answer 34

advantages
* cheap
* doesnt intefer with natural river
* ppl feel prepped & secure and can protect their stuff before = less impact
disadvantages
* some predictions may be wrong = unnecessary panic
* not everyone has access to media
* ppl actually have to do wht is said
* damage still occurs
* houses hard to sell
* distrupts habitats & ecosystems
* clear up is not good bc ppl forced into temp accom

Question 35

soft engineering

floodplain zoning

Answer 35

advantages
* lots of uk cities on floodplains
* cheap
* permeable surfaces remain
* damage is less expensive bc only low value is effected
disadvantages
* limits development bc certain land cant be used
* harded to enforce and plain in LICs
* habitats on other greenfield sites are destroyed as development is forced elsewhere

Question 36

soft engineering

planting trees

Answer 36

advantages
* co2 absorbed
* new habitat = increased biodiversity
* grants from government
* low maintance cost
* can be done in LICs bc of low skill involved
* reduces percipitation flooding bc interception
disadvantages
* large areas of land needed
* natural habitats changed from grass to trees

Question 37

soft engineering

river restoration

Answer 37

advantages
* boosts tourism
* little maintance
* biodiversity increase
* pretty
* businesses not affected
* reduces flood risk
disadvantages
* initial cost high
* pssible damage to land nearby