1. How Do Humans Impact Their Environment?

2. Water 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.

3. Vocabulary
Reservoir
Irrigation
Canal

4. Examples
The Aral Sea
Colorado River
Aswan High Dam

5. The Aral Sea
The 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.

6. The 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.

7. The Aral Sea

9. The Aral Sea

10. The Colorado River
The 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.

13. The Aswan High Dam
The Aswan High Dam was built on the Nile River in

14. Aswan 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.

15. Aswan 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.

19. Changing Landscapes
Humans change the landscape of the earth in order to farm or raise animals.

20. Examples
Agricultural Terracing
Polders
Deforestation
Desertification

21. Agricultural Terracing
People practice agricultural terracing in mountainous areas in order to make flat land to farm on.

22. Think!
Look at a map and try to think of some countries or areas where people may practice agricultural terracing.
A. The Andes Mountains in South America
B. The Himalaya Mountains in Asia

23. Agricultural Terraces in Peru

24. Cultivation of Rice in Terraces in China

25. Polders 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.

26. Netherlands without polders
Netherlands with polders

27. Deforestation
Deforestation is when humans cut down trees faster than they can grow back.

28. Deforestation 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.

29. Slash and Burn Farming
Slash 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.

30. Deforestation
Much 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.

31. Desertification
Desertification 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.

32. Desertification
The 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.

33. Desertification
Desertification 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.

35. Map of Western Africa showing Sahel

36. Pollution
Humans cause air, water, soil, and nuclear pollution that harm the environment.

37. Air Pollution
Air 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.

38. Acid Rain
A 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.

41. Water Pollution Water pollution is caused by:
Runoff that contains pesticides and fertilizers
Waste from heavy industry that contains metals and chemicals
Raw sewage
Oil spills and waste from ships

42. Water Pollution A few areas that have severe water pollution are:
Most of the rivers in Europe
The Ganges River in India

44. Nuclear Pollution
Radioactive waste from nuclear power plants must be stored in very safe areas otherwise it can contaminate the water and soil
Another 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

45. Chernobyl
In 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.

47. The Lost City
A lot of interesting photos of the city of Pripyat, a city near the power plant, which is abandoned to this day.