How do humans impact their environment?

Water Diversion/Management 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.

Examples The Aral Sea Colorado River Aswan High Dam

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.

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

The Aral Sea

The Aral Sea

The Colorado River The Colorado 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.

The Aswan High Dam The Aswan High Dam was built on the Nile River in 1960 - 1970.

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.

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.

Changing Landscapes Agricultural Terracing Polders Deforestation Desertification

Agricultural Terracing

Agricultural Terraces in Peru

Cultivation of Rice in Terraces in China

Polders

Netherlands without polders Netherlands with polders

Deforestation

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.

Desertification

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.

Map of Western Africa showing Sahel

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

Air Pollution

Acid Rain

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

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

Nuclear Pollution An 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

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.