CHAPTER 2.1 – CHAPTER 2.1 –

WATER SUPPLY AND WATER SUPPLY AND DEMANDDEMAND

I. HOW PEOPLE USE WATERI. HOW PEOPLE USE WATER People use water for household purposes, People use water for household purposes,

industry, transportation, agriculture, and industry, transportation, agriculture, and recreation.recreation.

However, water is not a resource of unlimited However, water is not a resource of unlimited supply. supply.

The Colorado River starts in Colorado as a huge The Colorado River starts in Colorado as a huge river. river.

But, as the river travels through Utah, Arizona, But, as the river travels through Utah, Arizona, Nevada, and California, many Americans tap into Nevada, and California, many Americans tap into the river for their water use. the river for their water use.

Given that the Colorado River is mainly Given that the Colorado River is mainly traveling through the desert, there is little traveling through the desert, there is little precipitation to refresh the water. precipitation to refresh the water.

As a result, by the time the river reaches As a result, by the time the river reaches the Gulf of California, it is dry.the Gulf of California, it is dry.

Therefore, water shortages due occur Therefore, water shortages due occur when:when:

– 1. Water is too little water because it is being 1. Water is too little water because it is being used faster that it can be replaced by used faster that it can be replaced by precipitation.precipitation.

– 2. The human water needs is greater 2. The human water needs is greater than the amount of water available. than the amount of water available.

A. IN THE HOUSEA. IN THE HOUSE

Water is an essential component in Water is an essential component in many modern day homes. For many modern day homes. For example, it is used for washing example, it is used for washing dishes, flushing toilets, and taking dishes, flushing toilets, and taking baths.baths.

B. INDUSTRY AND B. INDUSTRY AND TRANSPORTATIONTRANSPORTATION

Water is used in the creation of many Water is used in the creation of many products. However, water is also products. However, water is also used to cool down many machines. used to cool down many machines. Sometimes, this water can be Sometimes, this water can be recycled after use.recycled after use.

Water has been used in the past and Water has been used in the past and is currently used to transport people, is currently used to transport people, goods, and services.goods, and services.

C. AGRICULTUREC. AGRICULTURE

Farms need a constant supply of Farms need a constant supply of water for their crops to grow. The water for their crops to grow. The process of diverting water from a process of diverting water from a river to farm land is called irrigation.river to farm land is called irrigation.

In the U.S., water is mainly used for In the U.S., water is mainly used for irrigation.irrigation.

D. RECREATIOND. RECREATION

Water is used for fun in its liquid Water is used for fun in its liquid (swimming) and solid form (ice (swimming) and solid form (ice skating).skating).

II. CONSERVING WATERII. CONSERVING WATER

Def. of Def. of conservationconservation: the practice of : the practice of using less of a resourceusing less of a resource

Water can be conserved by Water can be conserved by reduction, recycling, and reuse.reduction, recycling, and reuse.

A. IN THE HOMEA. IN THE HOME

Don’t let the water run while Don’t let the water run while brushing your teeth.brushing your teeth.

Take shorter showers or use a low-Take shorter showers or use a low-flow showerhead. For every minute flow showerhead. For every minute you take a shower, you use 18 liters you take a shower, you use 18 liters of water.of water.

Only wash clothes with full loads.Only wash clothes with full loads.

B. IN INDUSTRYB. IN INDUSTRY

Industries are using cooling pools to Industries are using cooling pools to reuse the water needed to cool reuse the water needed to cool machines. machines.

The heated water is routed to a pool The heated water is routed to a pool where it is left to cool off. The cooled where it is left to cool off. The cooled water is reused.water is reused.

C. IN AGRICULTUREC. IN AGRICULTURE

Farmers are using sprinkler irrigation and Farmers are using sprinkler irrigation and drip irrigation to reduce the amount of drip irrigation to reduce the amount of water lost through evaporation.water lost through evaporation.

In sprinkler irrigation, water is sprayed In sprinkler irrigation, water is sprayed onto crops from overhead pipes.onto crops from overhead pipes.

In drip irrigation, pipes with tiny holes are In drip irrigation, pipes with tiny holes are placed on the ground. The pipes ‘drip’ placed on the ground. The pipes ‘drip’ water onto crops when needed.water onto crops when needed.

D. WETLANDSD. WETLANDS Def. of Wetland: a land area that is covered with Def. of Wetland: a land area that is covered with

a shallow layer of water during some or all of the a shallow layer of water during some or all of the year. The depth of water can be several year. The depth of water can be several centimeters to a few meters.centimeters to a few meters.

Wetlands help control floods by providing a place Wetlands help control floods by providing a place to hold water until it is needed for use.to hold water until it is needed for use.

Wetlands provide habitats for many species. For Wetlands provide habitats for many species. For example, there are three freshwater wetlands example, there are three freshwater wetlands found in our area: marshes, swamps, and bogs. found in our area: marshes, swamps, and bogs. In Florida, they have the Everglades.In Florida, they have the Everglades.

Nutrients from a wetland come from dead leaves Nutrients from a wetland come from dead leaves and plants as well as animal scat.and plants as well as animal scat.

III. BRINGING UP III. BRINGING UP GROUNDWATERGROUNDWATER

When water seeps into the ground, it travels through layers When water seeps into the ground, it travels through layers of permeable material such as sand and gravel.of permeable material such as sand and gravel.

The water eventually reaches a layer of nonpermeable The water eventually reaches a layer of nonpermeable material such as clay or granite. Since the water cannot go material such as clay or granite. Since the water cannot go through nonpermeable material, it will go back up into the through nonpermeable material, it will go back up into the permeable material.permeable material.

If the permeable material becomes totally filled with water, If the permeable material becomes totally filled with water, this is called the saturated zone.this is called the saturated zone.

The water found above the saturated zone is the water The water found above the saturated zone is the water table. table.

Water TableWater Table

A. AQUIFERS AND WELLSA. AQUIFERS AND WELLS

An aquifer is water An aquifer is water that is held in a that is held in a layer of permeable layer of permeable rock or sediment.rock or sediment.

It is brought up to It is brought up to the surface for use the surface for use by digging a well to by digging a well to it.it.

B. SPRINGS AND GESYERSB. SPRINGS AND GESYERS

A spring (low A spring (low pressure) and a pressure) and a gesyer (high gesyer (high pressure) is water pressure) is water that comes to the that comes to the surface of the surface of the Earth naturally. Earth naturally.

IV. FRESH WATER FOR THE IV. FRESH WATER FOR THE FUTUREFUTURE

Two ways of obtaining freshwater for Two ways of obtaining freshwater for the future: desalination and the future: desalination and icebergs.icebergs.

A. DESALINATIONA. DESALINATION Def. of Def. of desalinationdesalination: the process of making : the process of making

freshwater from saltwaterfreshwater from saltwater

There are three ways to desalinate:There are three ways to desalinate:

– 1. Boil the salt water. The fresh water will turn into 1. Boil the salt water. The fresh water will turn into water vapor and the salt is left behind. Cool the water water vapor and the salt is left behind. Cool the water vapor and then you have fresh water.vapor and then you have fresh water.

– 2. Freeze the salt water. The salt will sink to the bottom 2. Freeze the salt water. The salt will sink to the bottom and the freshwater will rise to the top.and the freshwater will rise to the top.

– 3. Pump the saltwater at a high pressure through a 3. Pump the saltwater at a high pressure through a filter. The filter will trap the salt but allow the filter. The filter will trap the salt but allow the freshwater to go through.freshwater to go through.

B. ICEBERGSB. ICEBERGS

Icebergs are towed to warmer areas Icebergs are towed to warmer areas to melt and provide fresh water.to melt and provide fresh water.