Water EQ2 Flashcards
1
Q
What are the 4 types of drought?
A
- Meteorological- shortfall or deficiency of water over an extended period
- Hydrological- reduced streamflow, lowered groundwater levels, reduced water stores
- Agricultural- famine, and starvation
- Socioeconomic
2
Q
What are the causes of meteorological drought?
A
- Research suggests sea surface temperature important factor in short-term precipitation deficits
- Physical causes on partially understood -complex interactions between different spheres
3
Q
How does El nino work?
A
- Strong trade winds push warm ocean currents to the east around South America, and leaving cooler ocean currents around Australia
- Occur every 3-7 years and usually last for 18 months
4
Q
How does la Nina work?
A
- Involve build-up of cool water around South America due to no trade winds- lead to severe drought conditions in parts of SA- Very warm water moving east- west
- Sometimes happens after EL nino
5
Q
What are the causes of desertification and where does it take place?
A
- Changing rainfall patterns
- Vegetation cover becomes stressed and begins to die leaving bare soil
- Bare soil eroded by wind and occasional intense shower
- When rain does fall only for short, intense periods- difficult for soil to capture and store it
- Usually takes place in semi- arid land on edges of existing deserts
6
Q
What human actions exacerbate desertification?
A
- Over-abstraction of surface water and groundwater
- Population growth- pressure on land to grow more food
- Overgrazing- destroy vegetation cover
- Overcultivation- exhausts the soil
- Deforestation- roots no longer bind soil and erosion occurs
7
Q
What human actions exacerbate desertification?
A
- Over-abstraction of surface water and groundwater
- Population growth- pressure on land to grow more food
- Overgrazing- destroy vegetation cover
- Overcultivation- exhausts the soil
- Deforestation- roots no longer bind soil and erosion occurs
8
Q
What is the situation with drought in Australia?
A
- It is a recurrent annual feature- up to 30% of the country is affected ( El Nino links)
- Careful management of scarce water resources- large scale recycling of greywater, desalination plants, and water conservation strategies
9
Q
Why are wetlands useful?
A
- Act as temporary water stores
- Recharge aquifers
- Trap pollutants
10
Q
How does drought impact wetlands?
A
- Less precipitation- less interception- less infiltration and percolation - water tables fall- increase evaporation and decreased transpiration
11
Q
How does drought affect forests?
A
- Increase sisceptibility of pines and firs to fungal disease
- Tree mortality increase
- less interception- reduced infiltration and overland flow
- Deforestation also has massive effects
12
Q
What are meterological casues of flood?
A
- Intense storms- lead to flash flooding- common in mountainous areas
- Prolonged, heavy rain- asian monsoon
- Rapid snow melt- siberia in warm spring
13
Q
What physical circumstances increase liklehood of flooding?
A
- low-lying areas with impermeable surfaces
- impermeable rocks on ground surface
- ice dams suddenly melt- glacial lakes released
- volcanic activitygenerates meltwater suddenly released- jökulhlaups
- earthquakes cause failure of dams or lanslides- bloking rivers
14
Q
What are some different human actions that exacerbate flood risk?
A
- Impermeable areas of tarmac
- Dams built to supply towns with water
- Ploughing compacts soil
- Deforestation stops woodlands from intercepting and transpiring
- pasteurised land does not allow water to sink in
- wells sunk to supply settlements.
15
Q
What are a few examples of river mismanagement of rivers using hard engineering?
A
- Channelization- improves river discharge and reduces flood risk, but it simply displaces the river downstream
- Dams- block flow of sediment down a river, so reservoir gradually fills up with silt- increases riverbed erosion downstream
- River embankments- designed to protect from floods, but they can fail when a flood exceeds there capacity- this makes the scale of flooding much greater.
