2Water Diversion/Management Humans need water to live and grow food. Humans have invented several techniques for managing water supplies such as building reservoirs and canals for irrigating crops and ensuring a constant supply of water.
5The Aral SeaThe Aral Sea is located in Central Asia between Kazakhstan and Uzbekistan. Since the 1960s it has been shrinking due to over irrigation. It is now 20% of its original size. The Soviets used the diverted water to irrigate cotton fields.
6The Aral Sea The shrinking of the Aral Sea has caused: The collapse of the local fishing industry.Increase in respiratory illnesses due to wind stirring up dust of exposed seabed.Extinction of plants and animals.
10The Colorado RiverThe Colorado River is an excellent example of how humans can impact the environment through irrigation. The River starts in Colorado and empties into the Gulf of California. On every stretch of the river farmers take water to irrigate crops. People have also built several dams on the river, the most famous is the Hoover Dam.
13The Aswan High DamThe Aswan High Dam was built on the Nile River in
14Aswan High Dam (Benefits) The dam provides around 15% of Egypt’s electricity.The dam has stopped the Nile River from flooding every year.The dam created Lake Nasser, which provides water for irrigation and local use.
15Aswan High Dam (Negatives) Around 90,000 people had to move.The dam blocks nutrient rich silt from being deposited on farmland and farmers have to use artificial fertilizers.Poor irrigation practices have led to an increase of salt in surrounding farmland.Fish stocks in the Mediterranean have depleted because the dam blocks nutrients from entering the sea.
25Polders A polder is an area of reclaimed land from the sea. Polders are found in countries with low elevations next to the sea such as Belgium and the Netherlands.Windmills were used to pump the water out of polders, but they have been replaced by diesel pumps.
26Netherlands without polders Netherlands with polders
27DeforestationDeforestation is when humans cut down trees faster than they can grow back.
28Deforestation A few causes of deforestation are: Forest land is cleared for farming or human settlement.Forests are cut down and the timber is sold.Slash and burn farming in tropical areas.
29Slash and Burn FarmingSlash and burn farming is a farming method used in tropical areas such as Brazil, Africa, and Southeast Asia. Farmers cut down the forest and burn the trees in order to fertilize the soil. After a few years the land becomes infertile and farmers must repeat the process.
30DeforestationMuch of the world has been deforested including Europe and many parts of the United States. Areas that are becoming rapidly deforested right now are mainly rainforests such as the Amazon Rainforest in Brazil.
31DesertificationDesertification is an expansion of arid conditions into a non-arid environment. Basically, desertification is when a desert gets bigger due to natural and human causes.
32DesertificationThe fringes of deserts are very fragile environments. If there is a long period of no rain such as a drought this area may turn into a desert. People can also cause desertification by cutting down trees near deserts or herding animals such as cattle, sheep, and goats.
33DesertificationDesertification occurs near deserts. The region directly south of the Sahara Desert in Africa is called the Sahel. This area has suffered from rapid desertification due to over grazing, droughts, and poor water management practices.
36PollutionHumans cause air, water, soil, and nuclear pollution that harm the environment.
37Air PollutionAir pollution is mostly caused by the burning of fossil fuels; oil, coal, and natural gas. Areas with many coal burning power plants, factories, and cars can experience acid rain.
38Acid RainA few areas that have acid rain are the Northeast United States and Canada, the Black Forest region in Germany, and China. Acid rain can kill vegetation and fish in streams and lakes over a period of time.
44Nuclear PollutionRadioactive waste from nuclear power plants must be stored in very safe areas otherwise it can contaminate the water and soilAnother example of nuclear pollution is when the Chernobyl nuclear power plant in the former Soviet Union exploded causing radioactive waste to contaminate the air and soil
45ChernobylIn 1986, one of the reactors at the nuclear power plant exploded causing a cloud of radioactive material that drifted and fell over parts of Russia and Europe. Over 300,000 people were forced to evacuate the nearby city of Pripyat and today the city is abandoned.