1. CHAPTER 2.1 – WATER SUPPLY AND DEMAND

2. I. HOW PEOPLE USE WATER  People use water for household purposes, industry, transportation, agriculture, and recreation.  However, water is not a resource of unlimited supply.  The Colorado River starts in Colorado as a huge river.  But, as the river travels through Utah, Arizona, Nevada, and California, many Americans tap into the river for their water use.

3.  Given that the Colorado River is mainly traveling through the desert, there is little precipitation to refresh the water.  As a result, by the time the river reaches the Gulf of California, it is dry.  Therefore, water shortages due occur when: –1. Water is too little water because it is being used faster that it can be replaced by precipitation. –2. The human water needs is greater than the amount of water available.

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

5. B. INDUSTRY AND TRANSPORTATION  Water is used in the creation of many products. However, water is also used to cool down many machines. Sometimes, this water can be recycled after use.  Water has been used in the past and is currently used to transport people, goods, and services.

6. C. AGRICULTURE  Farms need a constant supply of water for their crops to grow. The process of diverting water from a river to farm land is called irrigation.  In the U.S., water is mainly used for irrigation.

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

8. II. CONSERVING WATER  Def. of conservation: the practice of using less of a resource  Water can be conserved by reduction, recycling, and reuse.

9. A. IN THE HOME  Don’t let the water run while brushing your teeth.  Take shorter showers or use a low- flow showerhead. For every minute you take a shower, you use 18 liters of water.  Only wash clothes with full loads.

10. B. IN INDUSTRY  Industries are using cooling pools to reuse the water needed to cool machines.  The heated water is routed to a pool where it is left to cool off. The cooled water is reused.

11. C. IN AGRICULTURE  Farmers are using sprinkler irrigation and drip irrigation to reduce the amount of water lost through evaporation.  In sprinkler irrigation, water is sprayed onto crops from overhead pipes.  In drip irrigation, pipes with tiny holes are placed on the ground. The pipes ‘drip’ water onto crops when needed.

12. D. WETLANDS  Def. of Wetland: a land area that is covered with a shallow layer of water during some or all of the year. The depth of water can be several centimeters to a few meters.  Wetlands help control floods by providing a place to hold water until it is needed for use.  Wetlands provide habitats for many species. For example, there are three freshwater wetlands found in our area: marshes, swamps, and bogs. In Florida, they have the Everglades.  Nutrients from a wetland come from dead leaves and plants as well as animal scat.

13. III. BRINGING UP GROUNDWATER  When water seeps into the ground, it travels through layers of permeable material such as sand and gravel.  The water eventually reaches a layer of nonpermeable material such as clay or granite. Since the water cannot go through nonpermeable material, it will go back up into the permeable material.  If the permeable material becomes totally filled with water, this is called the saturated zone.  The water found above the saturated zone is the water table.

14. Water Table

15. A. AQUIFERS AND WELLS  An aquifer is water that is held in a layer of permeable rock or sediment.  It is brought up to the surface for use by digging a well to it.

16. B. SPRINGS AND GESYERS B. SPRINGS AND GESYERS  A spring (low pressure) and a gesyer (high pressure) is water that comes to the surface of the Earth naturally.

17. IV. FRESH WATER FOR THE FUTURE  Two ways of obtaining freshwater for the future: desalination and icebergs.

18. A. DESALINATION  Def. of desalination: the process of making freshwater from saltwater  There are three ways to desalinate: –1. Boil the salt water. The fresh water will turn into water vapor and the salt is left behind. Cool the water vapor and then you have fresh water. –2. Freeze the salt water. The salt will sink to the bottom and the freshwater will rise to the top. –3. Pump the saltwater at a high pressure through a filter. The filter will trap the salt but allow the freshwater to go through.

19. B. ICEBERGS  Icebergs are towed to warmer areas to melt and provide fresh water.