G4 revision

- Dam = A barrier that impounds water.

- Creates reservoirs that supress floods as well as providing water for irrigation, human consumption, industrial use, aquaculture and navigability.

- Hydropower is often used in conjuncton with dams in order to generate elecricity.

- A dame is also used to collct and/or store water which can then be evenly distributed beween locations.

Example = The Colorado river (USA):

• Known as the Hoover Dam.
• Built in the 1930's during the Great Depresssion.
• 112 deaths assciated with the construction.
• Harnesses the power of the Colorado river in order to generate reliable electricity.
• Supplies 18 million people with water.
• The construction of the dam has been criticised  because of its large impact on theColorado river delta - decline of the estuarine system.
• The delta's estuary once had a freshwater-saltwater mixing zone but this chnaged, the salinity level became higher at the river's mouth.
• The dam has eliminated natural flooding but animals an dplants that had adapted to the flooding environment have become threatened.
• The construction of the dam devastated the populations of native fish in the rivers downstream from the dam.
• Sediment lost to downstream ecosystems - removal of nutrients - loss of soil fertility.
• Jobs in contruction 3000 - 5000 per year (but temporary), new infrastructure and relocation.
• 40 million people displaced from dams in the past 10 years.
• Compensation plans have to be put in place e.g. Lesotho. Difficult to find land for families to grow crops on once they have been relocated.
• Resevoirs are the perfect habitats for vectors (mosquitoes and snails) and diseases (Malaria).
• Resettled groups end up living in densely populated areas - unsafe and poor sanitation.
• Generates 4 billion kilowatt-hours of hydroelectric power each year for use in Nevado, Arizona and California.
• Intensive water consumption dried the lower 160 km of the Colarado river so that it no longer reaches the sea except in years of heavy runoff.
• Created the biggest artifical lake in the USA - Lake Mead.
• Still water = less oxygen.
• The wtaer stored in lake Mead keeps digging the river bed.
• Lake Mead = decreasing in storage - 30 metres in 15 years.
• 50% chance of dissapearing before 2025.
• 800 litres of water per person, per day in Las Vegas.

• Creates more jobs
• Allows large ships to navigate the river and reach Chungong
• Has reduced coal consumption and consequently reduced CO2 emissions (by 31 million tonnes per year)
• Create thousands of jobs
• Develops new towns and farms
• Provides 10% of China’s electricity through HEP
• Increases tourism along the river
• Protects precious farmland from flooding
• However it also has a number of disadvantages:
• Downstream riverbanks becoming more vulnerable
• Over 150 towns and 4500 thousand villages will be flooded displacing people from their homes
• 1.3 million people will be forced to move
• The river landscape will be forever changed
•  The lake which will be created could become very polluted from industrial waste
• THE DAM SITS ON A SEISMIC FAULT
• The city of Shanghai sits on a massive sedimentary plain, erosion of this, and a lack of sediment to replace it, could prove fatal.
• Around 80 airline cracks observed in the dams structure.

• $62 million.
• Divert 44.8 billion cubic metres of water per year from the Yangtze River in  southern China to the Yellow River Basin in arid northern China.
• Equivalent to half of the amount of water cosumed by California annually.
• Displacement of hundreds of thousands of people - 330,000 people already (middle route alone).
• Carried out against the resistance of affected people - conflict.
• Project aims to curb the overuse of groundwater and supply more water to countries in the arid North who face the problems of climate chnage, water pollution and frequent droughts.
• Recent droughts in central China, did not have sufficient water for drinking or sowing crops, let alone sending to the north.
• Fears of pollution - render water unfit to drink due to contamination from factories along the river - worsened since the construction of the three gorges dam.

• The UK is highly variable in terms of water supply and demand.  A lot of the rainfall received by the UK falls in the North and West, whereas most people live in the South East.  This means that the North and West of the British Isles are WATER SURPLUS areas, whilst the south east is a water shortage area. 
• To combat this Northuimbria water, the company responsible for water supply in the North East, have constructed Kielder Water.  Kielder water is a management scheme designed to store water for the North East of England.  It is run by Northumbrian Water, a large company supplying Northumberland, County Durham and parts of North Yorkshire and Cumbria.
• The Kielder Water reservoir is in the North west of the region, so is in a high precipitation zone, and water is then piped and run through rivers to the cities that have a shortage of water in the East.  The differences in water received are clearly marked on the graph below, and the area in which Kielder is in receives 1700mm of rain a year, whilst Newcastle receives only 644mm!
• 8 sites of scientific interest.
• 11 km long lake containing 200,000 million litres of water - helps in time sof water shortage.
• Flood prevention measure.
• Visitors/tourism - £6 million a year.
• 2,700 acres of farmland an habitat lost.
• 58 families displaced.
• Clear water erosion further down stream.

• London clay is up to 80 metres thick and confines the chalk aquifer over most of London.
• Low storage.
• Groundwater flows into the Central London basin from the areas of recharge in the North West and South West.
• Water pumped into the confined chalk as water doesn't pass through the clay to reach it.
• Acts as a natural store of water.
• Criticism about the use of sewage water.

• Only possible in richer countries.
• 14,500 facilitis in 2010.
• The only climate independent source of water available.
• specific and expensive infrastrcture needed.
• Significant lack of rainfall drained water reserves during 2000-2010.
• Water levels dropped by 33% in  the Warragamba dam.
• First plant constucted in 1903.
• Expensive process.
• Research is underway to develop more effective desalination technology.
• 1% of desalination capacity is in Australia.
• Perth plant - installed in late 2006.
• Produces up to 45 gigalitres of water per year.
• Brine discharge shown to have no adverse impact on the environment.
• Buys power from electricty generated by the Emu Downs Wind Farm.
• Environmental impacts - greenhouse gas emissions (not in Australia due to the us eof wind power).
• Degradation of marine environments.

• NEWater is the brand name given to reclaimed water produced by Singapore's Public Utilities Board. More specifically, it is treated wastewater (sewage) that has been purified using dual-membrane (via microfiltration and reverse osmosis) and ultraviolet technologies, in addition to conventional water treatment processes.
• The water is potable and is consumed by humans, but is mostly used by industries requiring high purity water.
• Currently, the city-state boasts four NEWater plants, which have a combined capacity to meet nearly 30% of overall water demand. PUB believes that figure can be nearly doubled to 55% over coming decades.
• Main problem = negative attitudes to drinking the water.

• The only reliable source for renewable water supplies in the area.  The Entebbe Agreement has shifted control over the Nile away from Egypt and Sudan, who previously had a monopoly over the river’s resources as a result of colonial agreements. The food and water security situation in Egypt is extremely vulnerable, due to population growth and environmental factors that have raised deep concerns amongst the nation’s political leaders, already concerned about the geo-political shift in the Nile basin region. Multiple factors leave Egypt little choice but to engage in peaceful co-operation with other Nile nations to prevent future severe water scarcity. The Nile draws its water from three long rivers – the White Nile, Blue Nile and the Atbara, which flows from North-West Ethiopia to the Nile in East Sudan. The longest river in the world, the Nile stretches 6,650 km and passes through eleven countries. The volume of the Nile’s annual flow is 84 billion cubic metres. Combined population of over 450 million people and estimates indicate that over 200 million of them rely directly on the Nile for their food and water security. 

• Iraq, Turkey and Syria.
• Beginning in the 1960s - Turkey implemented a public-works project (theGAP project) aimed at harvesting the water from the Tigris and Euphrates rivers through the construction of 22 dams, for irrigation and hydroelectric energypurposes. Although the water dispute between Turkey and Syria was more problematic, the GAP project was also perceived as a threat by Iraq. 
• The 2008 drought in Iraq sparked new negotiations between Iraq and Turkey over trans-boundary river flows. Although the drought affected Turkey, Syria and Iran as well, Iraq complained regularly about reduced water flows. Iraq particularly complained about the Euphrates River because of the large amount of dams on the river. Turkey agreed to increase the flow several times, beyond its means in order to supply Iraq with extra water. Iraq has seen significant declines in water storage and crop yields because of the drought. To make matters worse, Iraq's water infrastructure has suffered from years of conflict and neglect.
• On September 19, 2009, Turkey formally agreed to increase the flow of the Euphrates River to 450 to 500 cms, but only until October 20, 2009. In exchange, Iraq agreed to trade petroleum with Turkey and help curb Kurdish militant activity in their border region. One of Turkey's last large GAP dams on the Tigris – the Ilisu Dam – is strongly opposed by Iraq and is the source of political strife.

• Between the 7 USA states of Mexico.
• The river is so overused that it no longer reaches the sea.
• 90% of the river is abstracted before it reaches the sea.
• 14 magor dams and resevoirs.
• 9 national parks.
• Hundreds of smaller dams.
• A network of aqueducts and canals.
• Provides water for moe than 25 million people in a semi-arid state.
• Water used to produce about 15% of the world's lifestock.
• Multi-billion recreational industry - hitewater rafting, boating, fishing and camping.
• Upper basin and lower basin recieve 45% of the water each, despite there being 3 states that are dependent in the lower basin, compared to fur in the upper basin. Mexico only recieves 10%.
• Population increase of 40% in the 1980's - lower basin.

• The media perpetuates negative stereotypes about Africa and other 'Thirld world countries.'
• The famine is a man-made crisis - inequitable global economic structures, geopolitics and climate change.
• When crops and lifestock perish in drought, it is the loss of ability to generate income, rather than the loss of food itself that is the cause of famine.
• Serial droughts in major wheat producing countries - high prices on the market - LEDC's can't compete.
• Prize of maize doubled.
• Food prices have rose by 39%.
• Key shipping channels targeted by airstrikes - debt.
• Foreign exchange needed to challenge the growing problem of debt.

• 58 million people are overweight.
• 40 million are obese.
• 3 million are morbidly obese.
• 78% do not meet recommended daily excercise levels.
• 70% - cardiovascular diseases.
• 26% high blood pressure.
• 4% of children overweight in 1982. 16% in 1994. 25% in 2001.

• Woodland degradation and deforestation due to population growth, urban expansion and increasing oil prices.
• Erosion - removal of sediment material by water flow or wind.
• Declines in crop yields.
• Siltation of smaller dams.
• Cultivation of maize (15 years) and Sorghurn (30 years) before the ground becomes to shallow.

Sahel Desert:

• Desertification - once productive land becomes infertile.
• Effects - soil is less usable, nutrients are removed by wind or water, salt build up due to cannal irrigation, lack or damage of vegitation, overgrazing - plant species lost, famine and food loss.
• Solutions - give farmers deeds so that they can use their farms as collateral to borrow money to invest, short term aid and should introduce farming technology on the front line and show farmers how to use it.

• Problem = One of the driest countries in the world, south of the Sahara Desert and people are poor, they have no money or water to spare.
• Solution = Plant trees that grow naturally in desert conditions and don't require water or nutrients, served more than 2,500 homes, direct seeding process and harvested fruits, berries and leaves that give a hosuehold £67 more a year.

• EU budget - 32% spent on CAP.
• Aims - to provide farmers with good quality lives, preserve rural heritage, promote producivity and provide consumers with good quality food at low prices.
• Three policies applied by 1962.
• Levies (applied to specific goods that enter the EU - making them more expensive) and import tarriffs (a means of restricting the amount of exports to the UK).
• Subsidies are paid directly to farmers so they can choose to grow crops that they know are in demand.
• - Rewards large farms, not small ones.
• - Environmental consequences.
• - Some say that it is a form of government intervention and that free trade should prevail.

• No water required, plants are panted on top of an enclosed chamber where they recieve maximum sunlight.
• The plants are suspended in air and are misted in water containing nutrients.
• The excess water drops down into the chamber and is used again.
• + Water isn't needed.
• + Almost any plant can grow using hydroponics.
• + Crops can be harvested all year long e.g. tomatoes, cucumbers and peppers.
• + Over 1 million plants in 7 greenhouses.
• + Uses recycled water from the roof.
• + Light pollution - 95% contained through the use of blinds.
• + 500 jobs
• - Wasteful use of heating and light
• - Eyesore
• - Cannot produce organic food
• - Without nutrients from soil, food tastes bland.

• Roots of the plants are suspended in the air. The plants are anchored in holes on top of a polysterene panel. Mist is sprayed and adheres to the plants.
• + Uses air which is important
• + Substantial savings in fertilisers and water
• + Saves land and water - most prized assests
• + Cleaner vegetables are produced
• + Uptake of oxygen onto a larger area - makes plants grow quicker.

• The emergence of aquaculture as an important and highly productive agricultural activity.
• Many species of freshwater fish and species are being cultivated as highly productive and nutritious crops for humans.
• Principle goal is to provide environments that enhance production.
• - Land, forests and mangroves are destroyed.
• - The salt water form the ponds seeps into the ground, destroying natural freshwater resources.
• Fish life in the sea is poisoned and reduced.
• Algae blooms.
• Access blocked to the sea from villages.
• 1998 - Governemnt banned salinity shrimp farming but protests were met and t was hard to enforce.
• Big environmental problems.

• Government does have the power to trial GM but it was met with backlash last time.
• Only one being trialled in Europe (Spain for use in animal feeds).
• 7 more in the pipeline in Brussels.
• Mixture of emotions and politics.
• 17 million farmers in 28 different countries are growing GM crops on 171 million hectares of land, 12.5% of which is arabal.
• 50 projects and 200 research groups.
• The use of technology and trials makes GM foods safer.
• + Next generation of GM could improve health - e.g. golden rice grain that can cure blindness but no one is willing to trial it. 500,000 go blind every year.
• + 24% yield increase potentially.
• + Pest resistant crops - increased yield.
• + Plastic.
• - Potential risks are still unknown.
• - Could pollinate organic crops.
• - Nut allergy sufferers.
• - Effect on bees.

• 7 point plan to increase development.

• Agricultural potential = 36 million ha, only 12.5% currently in use.
• Irrigation potential = 3.3 million ha, only about 50,000 currently in use.
• Almost self-sufficient in maize production but the internal market of grain is influenced by poor infrastructure.
• Mozambique needs to attract private investors by imroving infrastructure.
• 54% below the poverty line.
• 34% food insecure and face perpetual hunger.
• Needs to resolve land tenure problems.
• 7% growth in the past few years but wages have to increase in order to keep up with high high food prices - 85%.
• 5% growth predicted by 2025 - double food.
• Green revolution plan, food production action plan and investments by the private sector in industry and agriculture - if these occur, the country could fully resolve food shortages and high food prices would be a thing of the past.

• Need a steady power supply.
• Need good roads.
• Need basic pipelines for each citicizen.
• Need a good education system.
• Nee affordable housing.
• Need to tackle unemployment.
• Should be a very wealthy country - oil producer.
• But decades of corruption has taken its toll.
• Vast influx of people - fuelled unemployment and crime rates.
• But success is being made e.g. 90% electricity.
• Accute shortage of water supply.