5.5 Flashcards
What are the 2 causes of water surplus in the hydrological cycle
Meteorological- the weather
Hydrological- water stores
What are the meteorological causes of flooding?
Unusually heavy rainfall
Intense rainfall
Prolonged rainfall
Snow melt
Monsoon rain
What are the hydrological causes of flooding?
How is it Increased?
Tidal flooding, when high river flow meets high sea level
Increased by: impermeable ground, low lying land, earthquakes, jokulhaups
How do humans exacerbate flood risk?
Animal grazing soil- trampling compacts soil, impermeable
Ploughing field- compact soil, impermeable
Streams channeled into culverts- culverts can become blocked and no outputs for Streams
Dams- causes sediment to build up and block water
Irrigating crops- can oversaturate ground
Impermeable tarmac/concrete- more surface flow into river
Building on floodplains- more impermeable surface less infiltration
Natural grassland replaced by pasture- natural roots are bigger allowing more infiltration, pasture roots smaller
Deforestation- removes vegetation which takes up water
Channelisation of meanders- increases speed of river flow, more erosion
River embankments- once flooded, water can’t back over naturally
What are the impacts of flooding?
Socio-economic: Death, injury, damage to properties, destruction to crops
Environmental: recharged water stores, habitats destroyed, forces migration, increase in aquatic life, eutrophication kills species
A case study of flooding…
Storm Desmond
- Occurred in December 2015
Causes:
- Heavy prolonged rain on already saturated ground
-orographic precipitation, location
-relief of land
-anthropogenic climate change
-ENSO cycles
-Seasonal rainfall
-Urbanisation, impermeable ground
Socio-economic impacts:
-5200 houses flooded
-landslide closed west coast mainline
-£500m worth of damage
Environmental:
-habitats destroyed
-crops destroyed
What does eutrophication?
This is more nutrients in the water which increases growth of microorganisms which can deplete oxygen levels.
