Chapter 13 Water Resources - PowerPoint Presentation

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Chapter 13 Water Resources

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Contents

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2a. What percentage of the earth’s freshwater is available to us?0.024%

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2b. Define groundwater, zone of saturation, water table, and aquifer.

Water that infiltrates the ground through spaces in soil, gravel, and rock; found in the zone of saturation below the water table.

Zone where all available pores in soil and rock in the earth’s crust are filled with water.

Upper surface of the zone of saturation.

Geological layers of underground caverns and porous layers of sand, gravel, or bedrock through which groundwater flows.Slide5

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Fig. 13-3, p. 316Slide6

2c. Define surface water, surface runoff, and watershed (drainage basin).

Freshwater from precipitation and snowmelt that flows across the earth’s land surface and into rivers, streams, lakes, wetlands, estuaries, and ultimately the oceans.

Precipitation that does not infiltrate the

g

round or return to the atmosphere by evaporation.

Land from which surface water drains into a particular river, lake, or other body of water.

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2d. Distinguish between surface runoff and reliable surface runoff.Surface runoff we can generally rely on as a source of freshwater.

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3a. How is most of the world’s water used?70%, irrigation of crops20%, industry10%, municipal and domestic

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3b. Describe the availability an use of freshwater in the United States.More than enough renewable, but unevenly distributed and much is contaminated by ag- and industrial use.

The East: most used for energy production, power plant cooling, and manufacturing.

In arid and semi-arid West: most (85%) used for irrigation.

Half of water come from ground; rest, from rivers, lakes and reservoirs.

Hotspots (see Figure 13-5, p. 318)

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3d. What is drought and what are its causes and harmful effects?Condition in which an area does not get enough water because of lower than normal precipitation or higher than normal evaporation from higher temperatures.Causes: below normal rainfall, falling water tables (such as when ground water is overused), and climate change.

Dries soils, reduces stream flows, decreases tee growth and biomass, lowers NPP, reduces crop yields, and can shift biomes towards savannas and deserts.

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4a. What are the advantages and disadvantages of withdrawing groundwater?Back to Contents

Fig. 13-7, p. 321Slide12

4b. Describe the problems with groundwater depletion in the world and in the U.S., esp. the Ogallala Aquifer.Water tables fall½ billion people fed on grain grown with ground waterIn U.S., groundwater withdrawn 4x faster than recharge.

Serious overdrafts in lower half of Ogallala Aquifer; CA’s Central Valley (Fig. 13-9, p. 322)

Loses of ecological and agricultural productivity/loss of natural capital and ecological services.

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4c. Describe ways to prevent or slow groundwater depletion.

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Fig. 13-11, p. 324Slide14

5a. What is a dam?A structure built across a river to control the river’s water flow.

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5b. What is a reservoir?Artificial lake behind a dam.

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5c. What are the advantages and disadvantages of large dams and reservoirs?

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Fig. 13-12, p. 325Slide17

5d. What ecological services do rivers provide?

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Fig. 11-16, p. 270Slide18

6a. Describe the California Water Project and the controversy over this water transfer project.Dams, pumps and aqueducts transport water from water-rich northern CA to water-poor southern CA’s heavily populated ag-regions and cities.

Southern CA wants more water for crops and LA and San Diego.

Northern CA argues that Sacramento River is degraded cause or reduced flow, threatening fisheries and reduces river’s ability to flush pollutants out of San Francisco Bay; much of water sent south is wasted.Slide19

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Fig. 13-17, p. 330Slide20

6b. Describe the Aral Sea disaster.

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7a. Define desalinization and distinguish between distillation and reverse osmosis.

Removal of dissolved salts from ocean water or from brackish water in aquifers or lakes or domestic use.

Heating saltwater until it evaporates.

Also called microfiltration; use high pressure to force saltwater though a membrane filter with pores small enough to remove salt.

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7b. What are the limitations of desalinization and how might they be overcome?Limitations:High cost and large energy footprintKill many marine organismsConcentrated brine needs to be disposed of

Obstacles

New filtering technologies

Desalinization off-shore

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8a. What percentage of the world’s water is unnecessarily wasted and what are causes of such waste?65-70%CausesEvaporation, leaks, and other lossesLow cost

Lack of subsidies for improving the efficiency of water use.

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8b. Describe four irrigation methods and describe ways to reduce water waste in irrigation in developed and developing countries.Flood irrigation, gravity flowCenter-pivot, low pressure sprinklerDrip or trickle irrigation, also called micro-irrigation.

Rainwater harvesting

Polyculture

farming,

agroforestry

, and fog-

cather

nets.

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8c. List ways to reduce water waste in industry and homes.

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Fig. 13-22, p. 336Slide26

8d. List ways to use water more sustainably.

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Fig. 13-23, p. 337Slide27

8e. Describe ways in which you can reduce your use and waste of water.

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Fig. 13-24, p. 338Slide28

9a. What is a floodplain and why do people like to live on floodplains?Area adjacent to rivers where streams overflow the normal channels.Include highly productive wetlands, provide natural flood control, maintain water quality, and recharge groundwater.

People live there because of fertile soils, ample water for irrigation, transportation and recreation, and flat land suitable for crops, buildings, highways and railroads.

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9c. List three human activities that increase the risk of flooding.Removal of water-absorbing vegetation (see Fig. 13-25, p. 339)Draining and building on wetlandsBurning fossil fuels and clearing forests

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9e. How can we reduce the risk of flooding?

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Fig. 13-26, p. 340