Water Cycle Case Studies/ NecessaryFacts
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- Created by: Alemae
- Created on: 07-09-17 16:03
El Nino
El Nino
- It appears every 2 to 7 years and brings droughts an floods
- 6 months before its arrival is when El Nino can be predited (prediction not precise)
- Both El Nino and La Nina have the ability to change the climate across more than 50% of the Earth
- The La Nina that followed the 1997 El Nino lasted 33 months through 3 winters
Consequences (2015-2016 El Nino)
- 9-24 months is the duration of an El Nino
- 150,000 people in Latin America had to leave their homes due to flooding.
- 180,000 people in Ethiopia had to eave their homes due to flooding
- 8,000 domestic bovines in Zimbabwe died of hunger or thirt in the first drought months
1997 El Nino
- Killed estimates 23,000
- Caused as much as $45 billion in damage
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Sahel Region of Africa
Sahel Region of Africa (drought)
In the 1999-2000 Ethipian-Eritrean drought/famine crisis
- 10 million people needed food assistance
Physical Factors
- Drought sensitive as occupies a transitional cliate zone
- Normal conditions - mean annual rainfall (85%) is nearly all concentrated in summer
Human factors which made it worse
- Growing environmental degradation from overhgrazing of nomadic tribes
- Deforestation for fuelwood
- High levels of rural poverty
- Rural population densities increased (pop had x2 every 20-30 years)
- Population growth had outstripped food production in many areas
- Any agriculture was rain-fed
- Ethiopia and Eritrea were at war which bloked access to food for many
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California
California - What are the ecological impacts of drought?
- Nearly 90% in severe drought (2016)
- 4 year drought
- 58 million severely dehydrated trees = fire hazard
- 888 million trees experience water loss
- 29 million trees already dead
- El Nino hoped to bring rain
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Wetlands - S. Iraq
Wetlands - South Iraq
- Marshlannd in S. Iraq almost destroyed due to dams on Tigris and Euphrate
- Reduced flow
- Saddam Hussein's drainage schemes worsened situation as tried to destroy lifestye of 250,000 Marsh Arabs who lived there
- Overthrow of Saddam Hussein in 2003 - water flow. Extremely slow recovery of bad quality
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Monsoon Rain - Bangladesh
Monsoon Rain - Bangladesh
- 80% of Bangladesh's annual rainfall = June to October
- By end of monsoon season - almost 1/3 of country is underwater
- Some parts of the Ganges basin receive 500 mm of rainfall in a day during a monsoon
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Tewkesbury Floods 2007
Tewkesbury Floods 2007
Effects
- Nearly 50,000 homes affected
- 13 people died and hundreds had to be evacuated
- 9,000 businesses effected
- More than 180,000 insurance claims
- Flooding cost local councils £140 million
- 50,000 properties without power for 48 hrs
- 850 families had to stay in caravans, some up to Christmas 2008
- Agriculture sector severly effected due to sewage water
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Causes of Tewksbury Flood in 2007
Causes of Tewksbury Flood in 2007
Physical Causes:
- Geographical location - 2 big rivers (Severn and Avon) meeting in the town - confluence?
- Summer of 2007 was wettest since records began in 1766
- Little Sunshine - evaporation nope
- Intense rainfall
- Low pressure system located over Calais which moved N. West bringing warm air. Met cooler air of the North = instability ideal for storms
- Soils ALREADY SATURATED = MORE FLOODING
Human Causes
- Built on floodplains
- No flood defences in Tewksbury
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Citrarum River, Indonesia - Sewage
Citrarum River, Indonesia - Sewage
- Longest river in West Java
- Source of water for 25 million people
- Provides around 80% of surface water to Jakarta's water supply
- irrigates farms that supply 5% of Indonesia's rice
- Source of water for around 2,000 factories
- Around 5 million people live in the River's basin
- Poor sanitation and hygiene cause 50,000 deaths annually in Indonesia
- Nearly 1/2 million residents drinking water with lead concentrations x25,000 recommended level
- One of the world's most polluted rivers
- 46 thousand hectares of critical land in upper course of the river
- Used as toilet and garabage dump
- Smell sometimes makes people fall unconscious in summer
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Chemical Fertilisers
Chemical Fertilisers
What do they do?
- Fertiliers contain substances and chemicas like methane, CO2, ammonia and nitrogen = Global warming gases
- Nitrous Oxide, byproduct of nitrogen - 3 most significant greenhouse gas
- Nitrogen fertiliers break down into nitrates and travel easily through soil
- It is water-soluable and can remain in groundwater for decade accumualting
- Groundwater contamination linked to birth malformations and various cancers such as stomach cancer
- Dead zones - if chemical fertiliser enters a body of water, it adds more nutrients to it
- Algae rapidly grows as it is a plant blocking sunlight
- Other plants at the bottom cant photosynthesis and produce oxygen
- Dying algae feed microorganisms = even less oxygen
- Trout and salmon die when dissolved oxygen too low = carp takeover
- More than 400 of deadzones exist = 94,000 square miles of ocean
- Deadzone in Gulf of Mexico is rougly the size of New Jersey
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Industry and Water
Industry and Water
Examples of pollutants:
- Lead - non-biodegradable mterial and harful to health
- Oils - don't dissolve and can stop photosynthesis
- Nitrates - chemical fertilisers (eutrophication)
Causes:
- Policies not enforced - CHINA - TNCs
- Outdated technology = more polluting
- Unplanned industrial growth - New Dheli - hyper-urbanisation?
- Effects of Eutrophication
- Thermal pollution - Nuclear reactors leaving radiactive sludge in water = radioactive for DECADES - Japan 2011 Tsunami
Facts:
- Industrial pollution biggest source of polllution in most of developed world
- The Mississippi River dumps 1.5 million metric tonnes of nitrogen pollution inGuf of Mexico EVERY YEAR
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Over-abstraction of water
Over-abstraction of water
- In many areas of Europe - groundwater is dominant source of freshwater
- Take out too much = falling water tables
- Saline intrusion widespread on Mediterranean coastlines of Italy, Spain and Turkey - Tourism
- Malta - most groundwater can no longer be used for domestic consumption or irrigation due to the salt
- Irrigation is the main cause of groundwater over-exploitation in agricultural areas
Examples:
- E.g. Greek Argolid plain of Eastern Peloponnesus where it is common to find boreholes 400m deep contaminated by sea-water intrusion
- E.g. Italy - overexploitation of the Po river in the region of the milan aquifer has led to a 25m decrease in groundwater levels over the last 80 years
- E.g. Spain - more than half of the abstracted groundwater volume is obtained from areas facing overexploitation problems
- Across England, a third of river catchments threatened by excessively high abstraction levels
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California Take 2
California Take 2
Climate:
- Most of California is arid with annual percipitation at around 200-500mm
- 2.65% of water lost through evapotranspiration
- Only 22% for human use
- Mountain snow provides 1/3 of california's water supply
- By the end of the century, the Sierra snowpack is predicted to experience a 48-65% loss
River regimes in California:
- Population = 40 million people so pressure on rivers is intense
- Colorado River
- More thwan 30 dams in the Sierra will get new operating licenses by 2020 that require river restoration and protection measures
Geology
- San Andreas Fault - conservative plate boundary
- Sierra Nevada mountains
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Future trends for the world
Future trends for the world
- Hydrological cycle intensify = extremes more common (droughts and floods)
- The moisture holding capacity of the atmosphere will increase by 7% for every degree of climate change
- Are floods increasing, or simply just our vulnerability?
- Over past 30 years, droughts more intense, widespread and consistent (Australia)
- California's droughts
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Not enough water?
- Not enough water?
Physical distribution
- 60% of world's supplies contained in just 10 countries
- 66% of world's populaton live in areas receiving only 25% of world's annual rainfall
- Potential for conflict over trans-national boundaries
- Problems with supply and demand
Gap between rising demand and diminshing supplies
- 1950s - annual water withdrawal (km3) = 1,400
- 2000 - annual water withdrawal (km3) = 4,000
- Population 7 bn now but potential extra 3bn by 2030
Water availability gap:
- Rich countries use up to x10 more water per head
- By 2025 near 1/2 of the world's population iwll be water vulnerable
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