Deforestation issues in the Amazon
- Over 20% of the forest has been destoyed.
- Due to a combination of cattle ranching, large-scale commercial agriculture for biofuels and soya beans, general development of settlements and legal and illegal logging.
- Amazon rainforest covers 60% of the world's rainforests.
- Trees act as the lungs of the Earth, removing harmful CO2 from the atmosphere.
- Removal of these forests add CO2 and contribute to the greenhouse gas effect.
- Only 25% of water returned to atmoshphere by EVT when forests removed, compared to 75% when they are present.
- Creates a drier climate and the potential for a positive feedback loop.
- More water run off could lead to flooding, mudslides, aquifer depletion and increase soil erosion and soil degredation as nutriets are washed away.
Human Influences on Drought: Sahel, Africa
Sahel have high variability of rainfall at different scales:
1. Seasonally: African Sahel drought sensitive as it occupies a transitional climate zone. Annual rainfall concentreated in the summer, differeing from 100mm on the edge of the Sahara to 800m along its Southern margins.
2. Annually: from year to year there is huge variability, swarm sea surface temperatures in tropical seas will lead to strong convectional uplift, weaknening the monsoons and leading to drought in the Sahel.
3. Decadal: anomalies are very clear.
Human factors do not cause drought, but there is a strong correlation acting as a positive feedback loop. Drought impacts can be increase by socio-economic conditions from degredation of the environment, especiall with the 1999-2000 Ethipoian/Eritrean drought and famine crisis.
Population densities are increasing and most regions are still dependent on rains, espcially in agriculture.
Drought in Australia
The physical causes;
- Low, highly variable rainfall.
- Varying droughts - some intense and short lives, some last years (Big Dry of 2006).
- Australian droughts closely linked to El Nino events, e.g. East Coast drought in 2002-3.
- Shift in rainfall patterns in the east, where most live, becoming drier since the 1970s.
- 'Big Dry' thought to be associated with longer term climate change.
- 1/1000 year event spread nationwide
- Affected more than half of farmlands, espeically Murray-Darling Basin that provides 50% of agricultural outputs for the country
- Disasterous for wool, wheat and meat exports
- Reservoirs fell to 40% of their capacity
Over extraction of water sources is leading to further vulnerability for Australia, future demands are likely to exeed supply. Radical plans and schemes must be created and put in palce before Australia becomes too vulnerable.
The Impacts of Flooding in England and Wales/2007
- Over 3 months in the summer 397mm of rain fell, double aerage
- Northern areas badly hit by floods in Just
- West and South hit in July
- Wettest July on record
- Rainfall along RIver Severn hit record levels, a powerful storm sent the river into flood
- A dozen killed
- Financial costs amounted to £6 million
- River levels rose to 4.5m aboce normal
- Flooding hit some villages 6 times
- Unpredicitable flash floods occured
- Homes and buisnesses flooded, water supplies cut off, power supplies damaged
The Central Asian Highlands
Glaciers are a lifeline for 1 billion people in Asia, feeding rivers such as the Mekong, Yangtse, Yellow and Ganges.
Glacial melt maintains river discharge before and after summer monsoons, providing an abundance of water to be captured for agricultural and domestic use.
Of 680 glaciers monitored by Chinese scientists, 95% are shedding more ice than they are adding, leading to deterioration of mountain pastures.
The Aral Sea
- Was the world's 4th largest inland sea
- Soviet government diverted water from the two supplying rivers (Amy Darya and Syr Darya) for irrigation of agriculture and cotton fields
- An environmental catastrophe ensued
- Water levels dropped by 40m
- Sea shrank by 90%
- Disease, loss of buisness, higher mortality rate, collapsing economy all since occured
Kazakhstan secured massive World Bank loans to save the northern area.
- Former Soviet government
- The fishing community: 60,000 emplyees lost
- Local residents
- Uzebekistan and Kazakhstan governments
- Scientists, water engineers: monitoring and putting in place dams to bring back some water
Conflict in the Nile
- 6700km long, world's largest river.
- Nile basin covers 10% of African continent.
- 11 countries compete for Nile water, modest discharge of 84 billion cubic metres a year.
- Susceptible to varying discharge from high evaporation rates and seasonal changes in rainfall.
- 300 million live on the delta, expected to double to 600 million by 2030.
- Egypt reliant on the Nile for 95% of water needs.
- Many of the 11 countries have economic water scarcity issues.
- Growing demands and climate change mean 7/11 potentially water-scarce by 2025.
- Water scarcity will impact food security.
Water Transfers in China
South of China water rich with low population density, north of China water poor with high population density.
South-North water project began in 2003, expecting to last 50 years and cost US$100 billion on the building of three canals, spanning 1300km and connecting China's main 4 rivers: the Yangtze, the Yellow, the Huai and the Hai.
Plan on moving close to 50 billion cubic metres of water a year.
60% of the scheme will be paid for by the central government, the rest made up by local authorities that in turn charge for domestic and industrial usage.
Water conservation, improved irrigation, pollution treatment and environmental protection are being included in the plans.
There is still scientific concern on causing a full-scale ecological disaster.
Note: The Yangtze is severely polluted and the Yello is undrinkable.
The Sustainability of Singapore
NEWater is recycled from sewage but is heralded as cleaner than the standard set by the World Health Organisation the reclaimed water is treated conventionally first, then subjected to three additional purification processes. Has the capacity to meet nearly 30% of overall water demand.
Sky Green Farms is making farming vertical, minimising inputs of land and water by suspending plants in vertical racks rather than growing them in soil on the flat. It uses only 1 litre of water, collected through rainwater collection that is then recycled.
Smart monitoring of water reduces the water lost in leaky pipes, where only 4.6% of water is lost compared to other countries such as the UK, loosing over 20% (which is seen as doing well).
Finally, the government pushes messages about water conservation and ecology, reduced personal demand and then the need for supply.
Drainage Basin Management: the Colorado
- Between the basin states in the United States and Mexico has been conflict.
- 90% of water used before it reaches Mexico.
- 80% received by farmers who waste it on inappropriate crop choices and poor irrigation.
- Cities like LA and Las Vagas ly o the river with increasing demands and growing populations.
- 2012 US and Mexico signed the treaty
- US is now able to send Mexico water equivalant to supply, before they had to send enough to supply 3 million homes no matter river level.
- In return Mexico is allowed to store surplus water in flood years in dams within America.
Avoiding Conflict in the Nile
1929: Nile Waters Agreement signed, giving 48 million cubic metres to Egypt and 4 billion to Sudan, only 14% going to other African countries. Egypt was given the right to veto use of water in other nine nations.
1959: second Nile Waters Agreement signed, giving 55.5 billion cubic metres to Egypt and 18.5 billion to Sudan, the rest of the water was lost in evaporation. Signed by colonial powers on behalf of upstream nations, though Ethiopia refused to recognise its legitimacy.
Sudan and Egypt have ever-increasing needs for Nile water.
Nile Basin Initiative emerged in the 1990s, which 9/11 Nile basin countries have been exploring since 2005 with the partnership with organisations like the World Bank to establish a common vision.
Eastern Nile Program and Nile Equatorial Lakes Program and subsidiaries that have been established.