Uses for Water

Text pages 323 -326

Section 20.1

Why care about water?• Video (Short)• Global Water Shortage:

Scarcity of fresh water

• On a global basis, fresh water is a increasingly scarce resource. It is partially caused by increasing population coupled by change of consumption pattern and climate changes.

Fresh Water supply

Three Main Uses of Water

• Residential Use– 9%

• Industrial Use– 44%

• Agricultural Use– 47%

Percentage of water

Water uses in the USagricultural 47%residential9%industrial44%

47%

9%

44%

Water Uses in the United States

agricultural

residential

industrial

Competing water uses (I)

Residential Water Use:

• How many liters of water do you think you use on a daily basis?

Residential Usage Facts

• The average person uses 300 L of water daily.

• A lawn sprinkler uses up to 40 L of water every minute.

• Daily uses– Brushing teeth – 19-39 L– Showering 75-80 L– Bathing (tub) 96-116 L – Clothes washing 140-170 L

Industrial Uses• Transport goods

• Dispose of wastes (diluting waste products with water)

• Used to cool the power-producing equipment• Sanitation needs within the facility

• Processing of product

Industrial Uses

• Some industries that use large amounts of water produce– Food– Paper– Chemicals– refined petroleum– primary metals

True or False

1. It takes 10 gallons of water to produce 1 can of soda.– True or False

2. It takes 2000 gallons of water to manufacture one car.

-True or False

Water consumption for food production (I)

• Meat production use a lot of water when compared to growing food crops.

• A shift in food consumption pattern toward more meat consumption will cause a substantial increase in water consumption.

• How much water does it take to make a hamburger?

634 Gallons(amount needed to grow the cattle and produce and deliver the hamburger)

Thermoelectric Power Water Use

• Production of electrical power results in one of the largest uses of water in the United States and worldwide.

• In 2005, 201,000 million gallons of water each day were used to produce electricity (excluding hydroelectric power).

Thermoelectric Power

• One of the main uses of water: to cool the power equipment (creates hot water)

• This used water must first be cooled before it is released back into the environment (rivers). Why is this?

• Hot water is cooled in large cooling towers through evaporation

Cooling Technologies• Closed-cycle systems discharge heat through

evaporation in cooling towers and recycle water within the power plant. The water required to do this is comparatively small since it is limited to the amount lost through the evaporative process. Because of the expense associated with closed-cycle cooling, once-through systems are far more common.

• Once-through systems require the intake of a continual flow of cooling water. The water demand for the once-through system is 30 to 50 times that of a closed cycle system.

Agricultural Use

• Irrigation – the process of bringing water to an area for use in growing crops.

• Main types– Flood – flooding of an area that is flat– Furrow- releases water into ditches dug

between crop rows– Overhead irrigation – sprinkler systems and

drip or trickle from above the crops.– Subirrigation – water is introduce beneath

the soil

Problems Related to Water crisis

• Inadequate access to safe drinking water by over 1.1 billion people

• Groundwater overdrafting leading to diminished agricultural yields

• Overuse and pollution of water resources harming biodiversity

• Regional conflicts over scarce water resources sometimes resulting in warfare

Threats to fresh water resources

• Climate change causes change in frequencies of droughts and floods.

• Depletion of aquifers caused by over-consumption as a result of population growth.

• Pollution and contamination by sewage, agricultural and industrial runoff.

Distribution of population and water resources

Desalination of sea water as fresh water supply

• Desalination of sea water can be done either via distillation or membrane process.

• Both process requires large amount of energy and thus costly, which means desalination remains an expensive option for providing reliable fresh water supply, restricted to only economically well-off countries.

Use your text to find the benefits and limits of each type of irrigation

• Flood Irrigation -

Use your text to find the benefits and limits of each type of irrigation

• Furrow Irrigation -

Use your text to find the benefits and limits of each type of irrigation

• Overhead Irrigation – Sprinklers -

• Drip or trickle -

Use your text to find the benefits and limits of each type of irrigation

• Subirrigation