Human activity and drought Flashcards
Rio drought 2014/15:
- Worst drought in (1) years
- Driest region had less than (2)mm of rainfall than usual
- (3) system over Brazil but heavy rainfall in (4)
- Water rationing affected (5) people and got cut in some areas for (6) days
1 - 80 2 - 100 3 - high pressure 4 - Paraguay and Bolivia 5 - 4 million 6 - 3
Rio drought 2014/15
- Power cut due to halted (1)
- (2) of the largest reservoirs dangerously low, some down to (3)%
- Reduced crops of (4) increased global prices over 50%
1 - HEP
2 - 17
3 - 1
4 - Arabica beans
Tipping point:
- Rainforests recycle (1)% of their rainfall
- (2) feedback loop from deforestation and (3) so there is less capacity to regenerate and therefore less (4) and storage
1 - 50
2 - Positive
3 - less precipitation
4 - resilient
Tipping point:
- Global climate change so the (1) cycle and deforestation makes (2) more frequent
- Less absorption of (3)
- Change in regional (4) and an increase in (5) temperature
1 - ENSO 2 - extreme weather 3 - carbon 4 - water cycles 5 - soil
Tipping point:
- Biome change to (1)
- More (2) and so more carbon
- Less dependence on HEP which provides (3) of energy
- Loss of (4) as rainforest
1 - Savannah
2 - wildfires
3 - 70%
4 - carbon sink
Define ‘positive feedback’
A cyclical sequence of events hat amplifies or increases change
Define ‘negative feedback’
A cyclical sequence of events that neutralises the effects of a system
Rio drought not just (1) also contributed by (2) of surface water and ground water (3). Sao Paulo heavily industrialised and shanty towns so (4) is sole supply Government charge (5) to drill a well (6)% of new wells are illegal as they are not registered and so not checked for safety
1 - meteorological 2 - over extraction 3 - aquifers 4 - groundwater 5 - $3,000 6 - 70
Drought in the rainforest:
- (1) billion trees absorbs up to (2) billion tonnes of water vapour daily
- River carries (3) million tonnes back to the Atlantic a day
1 - 400
2 - 20
3 - 17
Drought in the rainforest:
- Younger trees die reducing (1) cover
- Less humidity and (2) so less rainfall
- More tropical sunlight increases (3) vegetation and (4)
1 - canopy
2 - vapour
3 - dying
4 - wildfires
Define ‘drought’
A period of time when weather is abnormally dry which causes a serious hydrological imbalance in a specific region
Why is drought a ‘creeping hazard’?
Typically long onset and so difficult to determine a start date
Areas severely affected by drought has increased to (1) of global land in the past 30 years
30%
What is the cause of meteorological drought?
Rainfall deficit
What are the main features of a meteorological drought?
- Lack of rainfall
- Lack of snow cover
- Strong winds
- High temperatures and solar radiation
How can the severity of a meteorological drought be measured?
Palmer Drought Severity Index (PDSI)
- Duration and intensity of atmospheric conditions
- For long term drought
Crop Moisture Index (CMI)
- Short term soil moisture conditions monitored by farmers during growing season
What is the cause of socio-economic/ famine drought?
Food deficit
What are the main features of socio-economic drought?
- Desertification
- Loss of vegetation
- Increased wildfire risk
How might governance and development increase vulnerability to socio-economic drought?
- Higher income sources increases dependence on imports
- Poor governments may not distribute or store resources effectively
What is the cause of hydrological drought?
Stream flow deficit
What are the main features of hydrological drought?
- Reduced infiltration and percolation
- Groundwater not recharged
What is the cause of agricultural drought?
Soil moisture deficit
What are the main features of agricultural drought?
- Low EVT
- Plant water stress
- Reduced biomass
- Reduced groundwater level
What human factors lead to agricultural drought progressing to famine drought?
No crops stored or saved
What are the physical causes of drought in Australia?
- El Nino
- Shift in rainfall patterns so densely populated East coast has become drier
- Long term climate change is blamed for the ‘Big Dry’ in 2006
- Sub-tropic high pressure weather system
Australia’s Big Dry 2006:
- (1) drought event commenced in the (2) drainage basin
- Australia’s (3) heartland
- Disastrous impacts on (4) supply
- More than (5) farming families had to leave their land
1 - 1-in-1000-years 2 - Murray-Darling basin 3 - Agricultural 4 - Food 5 - 10,000
Australia’s Big Dry 2006:
- Normally the country harvests 25 million tonnes but crop yield was down to (1)
- Reservoirs fell to (2) of their capacity
- Schemes to meet water demand include recycling of (3), (4) plants and conservation
1 - less than 10 million
2 - 40%
3 - grey water
4 - desalination
Sahel drought:
- Variable rainfall which is between (1)
- Often attributed to (2) cycles
- Human factors are not the cause but act as a (3)
- During Ethiopian-Etritean drought 1999/2000, (4) needed food assistance
1 - 100mm (Northern) to 800mm (South)
2 - ENSO
3 - Positive feedback loop
4 - 10 million people
Sahel drought:
- Socio-economic conditions associated with environmental degradation from (1), deforestation for (2) and rural (3) worsened impacts
- Desertification so semi-arid regions are (4) so vegetation dries and land becomes susceptible to (5)
1 - overgrazing 2 - fuelwood 3 - poverty 4 - over cultivated 5 - erosion
Sahel drought:
- Regional population doubles every (1)
- Agriculture is exclusively (2)-fed
- (3) meant food aid was blocked
1 - 20-30 years
2 - rain
3 - political instability
