Rivers - Floods Flashcards
1
Q
Flooding
A
where land that is normally not underwater becomes submerged
2
Q
infiltration
A
Water sinking into the soil from the ground surface
3
Q
discharge
A
amount of water than passes a given point on a stream or river bank within a given period of time
4
Q
interception
A
water prevented from reaching the surface by trees and grass
5
Q
physical causes
precipitation
A
- 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
6
Q
physical causes
geology
A
- 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
7
Q
physical causes
relief
A
- 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
8
Q
human causes
urban land use
A
- 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
9
Q
human causes
rural land use
A
- 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
10
Q
effects
social
A
- Injury
- Death
- Loss of home
- Loss of belongings
- Damage to property
- Stressful
- Isolate – loss of roads
- Loss of recreational facilities
11
Q
effects
economic
A
- Rebuild/fixing damage
- High insurance claims
- Loss of work/employment
- Loss of revenue for local area
- House value could decline
12
Q
effects
enviornmental
A
- 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
13
Q
Flashy Response
A
when a drainage basin responds quickly
14
Q
flashy hydrogaphy
basin size
A
small basins often lead to rapid water transfer
15
Q
flashy hydrogaphy
drainage density
A
high density speeds up water transfer
16
Q
flashy hydrographs
rock type
A
impermeable rocks helprapid overland flow
17
Q
flashy hydrogaphy
land use
A
urbanisation = rapid water transfer
18
Q
flashy hydrogaphy
relief
A
steep slopes = rapid water transfer
19
Q
flashy hydrogaphy
soil moisture
A
saturated soil= rapid overland flow
20
Q
flashy hydrogaphy
rainfall intensity
A
heavy rain may be more than vol that can be intercepted = rapid overland flow
21
Q
flat hydrograph
basin size
A
large basin = slow water transfer
22
Q
flat hydrograph
drainage density
A
low density = slow water transfer
23
Q
flat hydrograph
rock type
A
permeable rock = slow water transfer bc it mves in groundwater flow
24
Q
flat hydrograph
land use
A
forest = slower water transfer bc interception
25
# flat hydrograph
relief
gentle slopes = slower water transfer
26
# flat hydrograph
soil moisture
dry soil =slower water transfer
27
# flat hydrograph
rainfall intensity
light rain = slower transfer
28
# hard engineering
embankents
**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
29
# hard engineering
flood relief channel
**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
30
# hard engineering
dams & reservoirs
**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
31
# hard engineering
channel straightening
**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
32
hard engineering
use of artificial structures to prevent or control natural processes
33
soft engineering
work with natural river processes to manage the flood risk
34
# soft engineering
flood warning and prep
**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
35
# soft engineering
floodplain zoning
**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
36
# soft engineering
planting trees
**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
37
# soft engineering
river restoration
**advantages**
* boosts tourism
* little maintance
* biodiversity increase
* pretty
* businesses not affected
* reduces flood risk
**disadvantages**
* initial cost high
* pssible damage to land nearby
