The Water Cycle And Water Insecurity Flashcards
What is a drought?
A period of below average precipitation in a given region resulting in prolonged shortages in water supply
What is water scarcity?
When the demand for clean fresh water exceeds the available supply
Why is drought called a creeping hazard?
As drought has a long period of onset so it is hard to tell if its just a dry period or drought
What are the four types of drought?
Socio-economic drought
Hydrological drought
Agricultural drought
Meteorological drought
What is Meteorological drought?
Occurs when actual rainfall in an area is significantly lower than then climatological mean of that area
What is agricultural drought?
Lack of sufficient moisture in the surface soil layers to support crop and forage growth
What are indicators of agricultural drought?
Precipitation (reduced)
Temperature (increased)
Soil moisture (reduced)
What is socioeconomic drought?
Demand for an economic good exceeds supply as a result of a weather related deficit in water supply
What is hydrological drought?
The effects of periods of precipitation (including snowfall) shortfalls on the surface or subsurface water supply (reservoir, lake levels)
What are the three atmospheric cells?
Hadley
Ferrel polar
What is an example of an extreme meteorological drought?
ENSO
El Niño southern oscillation
2003 European drought
What are the three phases of El Niño?
Neutral phase (normal)
El Niño (negative phase)
La Niña (positive phase)
What is neutral ENSO like?
Trade winds blow from S.Am to AUS (easterly trade winds)
Warm surface water advected to western side of basin
Evaporation higher at area of warm water pool (west/ AUS)
More warm wet air near AUS
Air rises, cools and condenses
Rainfall over AUS coastal regions
Atmospheric divergence over AUS
Cold dry air sinks over AUS and S.Am
Upwelling near S.Am
What is upwelling?
When the warm water sinks by Australia it becomes cold and dense it moves towards S.Am and then rises to replace moving warm water
What is the positive of Neutral phase for S.Am/
Upwelling makes nutrient rich water that is good for fishing
What are conditions like for El Niño?
Weakening of easterly trade winds (reversal- extreme)
Trade winds don’t reach AUS
Warmer water centred in centre of equatorial pacific
Evaporation is higher in this area (warm air rises, cools ,condenses)
Rainfall
Air sinks over AUS causing dry coastal conditions
Weaker upwelling
What are conditions like for La Niña?
Stronger then normal easterly trade winds
Warm water advected closer to the Australian coast
normal rain production processes
Rainfalls just more inland then neutral phase
Flooding in AUS
Atmospheric divergence
Cold dense air sinks over S.Am leading to dry/arid conditions
Good commercial fishing in S.Am
Very strong upwelling
How does ENSO affect the globe?
Heats up equatorial Atlantic
Increasing chance of storms as water might more readily reach 26.5*c needed for hurricanes
What were the impacts on Australian climate from El Niño? (2014-16)
Counteracted by warm temp in Indian Ocean causing above average rainfall
Spring 2015 Australias third driest spring
Fewer clouds and less tropical rain resulted in mot severe coral bleaching on record
Bushfire season started earlier
Less rainfall
Increased temperature
Increased frost risk
Later monsoon onset
Increased fire risk
What were the effects on the South American climate from El Niño? (2014-16)
September and December 2015 were generally dry
South east Brazil experienced extreme drought in 2015
Above average temperatures and decline in several rivers and reservoirs (Brazil)
Residents had to save water, cutoffs made
South region experienced a period of severe thunder storms causing flooding and homelessness
What are the impacts of La Niña on the Australian climate? (2020-22)
Last La Niña was from 2010-12 wettest 2 yrs on record
Widespread flooding
5 tropical cyclones were in the severe category
Above average rainfall
Colder days
More tropical cyclones
Earlier onset of wet season
What are the impacts of La Niña on the South American climate?
Positive impact on fishing industry (strong upwelling)
Drought affects coastal regions of Peru and Chile
December to February Brazil is wetter than usual
Higher then average rainfall in central Andes which causes catastrophic flooding
What happened in August 2003?
An anticyclone stationed above Western Europe prevented precipitation and led to record high temperatures over sustained periods
What type of system is an anticyclone?
High pressure
What is the processes of a heatwave?
Anticyclone
High pressure
No clouds
No rain
Sunny hot days
What areas was most affected by the heat of the 2003 heatwave?
France where temperatures met 40*c for mote than a week in some areas
How long was it before there was precipitation in Europe again after the 2003 heatwave?
2 weeks for much of Europe
What concerns were raised after the 2003 heatwave?
Anthropogenic climate change was partly the cause of such a severe heat wave
What area experienced extensive forest fires in the 2003 heatwave?
Portugal
5% of countryside and 10% of forests were destroyed
How many heat related deaths were there in France and Portugal?
France 21000
Portugal 2100
What were the effects on agriculture during august 2003?
Crops suffered from drought in Southern Europe
How was Wheat affected by the 2003 heatwave?
All reductions
France= 20%
Italy= 13%
UK= 12%
EU 10%
What one agricultural product increased during the 2003 heatwave?
Grapes
Why did the grape market increase?
Heatwave accelerated the ripening
Wines from 2003 have exceptional quality (mostly french wine)
How did the UK wine benefit form the heatwave?
The uk did quite well in the international wine contests
How were livestock affected by the 2003 heatwave?
Many chickens, pigs and cows died
What happened to the food market in 2003/04?
Prices increased due to supply and demand being affected
How much did the 2003 heatwave cost the EU farmers?
13.1 billion euros
What were the social impacts of the 2003 heatwave?
Reservoirs and rivers used for public water supplies and HEP dried up or ran extremely low
Hosepipe bans
Many peoples older relatives died
What happened to nuclear power during the heatwave?
In the UK 2 nuclear power stations had to shut down as cooling water ran out and became too hot
What are some examples of drought caused by human factors?
The Sahel
Recent Australian drought
What is the Sahel?
A semi-arid region spanning much of central/ North Africa
Covers 11 countries but has become more and more arid and larger over time
What has been happening in the Sahel since the 1960’s?
Has been decreasing rainfall levels and droughts are becoming more severe
What does an increase in drought mean for the Sahel?
A decrease in crop growth
How long. Was the millennium drought?
Lasted for 12 year from 1997-2009
The most severe years were 2001-2009
How does the removal of vegetation affect water cycling?
A vegetated environment has high evapotranspiration so all of water returned to the atmosphere
A deforested environment has low evapotranspiration so water doesn’t return to atmosphere as readily
What are the purely physical causes of drought in the Sahel?
El Niño event can increase drought as it brings a easterly wind which added to drying conditions
Particularly affects western Sahel
La Niña also seems to interrupt rainfall (2011)
What are the human and physical causes of drought in the Sahel?
Pollution in Europe and North America changed the heat budget and atmospheric circulation so tropic storms linked to ITZC don’t arrive as it shifts south
NOAA suggests higher sea surface temperatures caused by anthropogenic climate change
Rain bearing winds of Sahel fall if the sea surface is warmer than average
What are the humans causes of drought in the Sahel?
High poverty rates and low development rates which mean high population growth rates
Lack of energy resources mean fire wood is main fuel source (reduce tree cover and evap-trans)
Land grabbing of most productive land
Over grazing
How do poverty rates affect drought? In the Sahel
The population grows 2.5-4% a year increasing demand for food meaning land is being over cultivated
How does the use of wood as fuel affect drought?
Reduces water recycling and reduction of vegetation cover increasing desertification and drought
40% of an area typical rainfall comes from evapotranspiration
How does land grabbing affect drought?
Increases water use and pushes local subsistence farmers out onto more marginal land increasing dry land removal
How does overgrazing affect drought?
Caused by population rise (demand) reducing size of grazing land
Increasing cattle per square km causing overgrazing and lack of vegetation to hold moisture
Where was the most affected area of Australia? (Drought)
Below average to record low rainfall across much of southwest and south east Australia
What were the physical causes of the millennium drought?
ENSO was one of the main contributing factors
ITZC which is a fluctuating band of Rain fall between the tropics that is slowly shifting north away from Australia
How do humans contribute to the millennium drought?
Murray darling basin the water channel was being over abstracted for irrigation of water intensive crops like rice.
What were the environmental impacts of the millennium drought?
Oxygen levels decreased due to over abstraction of water and algae dying so fish populations dwindled
Cattle culled for going on peoples land for water or just dying from dehydration
Largest recorded mangrove die back
Wildfires destroying vegetation and animal habitats
What were the social impacts of the millennium drought?
Low rainfall in growing period led to crop failures
Had to import food so food prices increased for the whole country
Water restrictions enforced (4 minute showers)
Rural populations fund it hard to access clean drinking water and staple foods
What were the economic impacts of the millennium drought?
Food prices increased due to importing large amounts of food
Agricultural income fell by 46.2%
Agricultural employment reduced by 100,000
Price of livestock goods increased
Ships had difficulty managing reduced flow channels
Payment for water transport
