13-4 Is Transferring Water from One Place to Another the Answer?

• Concept 13-4 Transferring water from one place to another has greatly increased water supplies in some areas, but it has also disrupted ecosystems.

Water Transfers Can Be Wasteful and Environmentally Harmful

• Using a lot of water to produce a water thirsty plant, like ________________, is not necessarily a bad thing…if the crop is grown in areas with ___________ of water

• However, U.S. lettuce primarily comes from California’s _____________ Central Valley area, and requires the use of heavy _________________

lettuce

a lot

aridirrigation

Southern California Lettuce Grown with ________________ California Water

Fig. 13-15, p. 331

Northern

California Transfers Water from Water-Rich Areas to Water-Poor Areas• Water ________________ from north to south by• Tunnels• Aqueducts• Underground pipes

• This water transfer project is called the ___________________ ___________ ___________• ___________________ water use in arid regions• Environmental damage to _______________ River

and San Francisco ___________

transferred

California Water ProjectInefficient

SacramentoBay

Fig. 13-16, p. 331

Shasta Lake Oroville Dam and

NEVADA

Sacramento RiverUTAH

CALIFORNIA

North Bay Aqueduct

Feather RiverLake Tahoe

San FranciscoSacramento SIERRA MOUNTAIN RANGE

South Bay Aqueduct

San Joaquin Valley Los Angeles Aqueduct

California AqueductColorado River

Aqueduct

ARIZONA

Colorado River

Fresno

Hoover Dam and Reservoir (Lake Mead)

Santa Barbara

Los Angeles

Central Arizona Project

San Diego Salton Sea Phoenix

Tucson

MEXICO

Reservoir

San Luis Dam and Reservoir

California Transfers Water from Water-Rich Areas to Water-Poor Areas• Projected climate change may make situation

worse…• snow packs in the _________ ______________

mountains may…• melt _________________• Receive ___________ precipitation during drought

years

• Some analysts project that during this century, many people living in arid, Southern California cities, will have to _______________ elsewhere

High Sierra

fasterless

move

Case Study: The Aral Sea Disaster (1)

• The ___________ Sea was once the world’s _______ largest lake

• 1960: has been used for a

large scale water transfer to irrigate one of the driest areas in central _____________• Cotton and rice

Aral

4th

Asia

Natural Capital Degradation: The Aral Sea, Shrinking Freshwater Lake

Fig. 13-17, p. 332

Case Study: The Aral Sea Disaster (2)

• The large scale water transfer was also coupled with…• _____________________• High ________________ rates

• Since 1961…• Water levels have dropped by an amount equivalent

to a _____________ building• the sea’s salinity (___________ content) has risen

_________________________

drought

evaporation

6-story

saltseven-fold

Case Study: The Aral Sea Disaster (2)

• 85% of the area’s ________________ have been eliminated

• ___________ of local bird and mammal species have disappeared

• Devastated the area’s ______________ industry

• The southern portion of the Aral Sea is now a desert covered with glistening white _______________

wetlands

Half

fishing

salt

Case Study: The Aral Sea Disaster (2)

• Wind-blown salt and dust ________________ other fields and wildlife areas• Settling on the __________________ in the Himalayas

causing them to melt at a ____________ rate

• To increase yields, farmers are using _________ herbicides, insecticides, and fertilizers, which have percolated into the ___________________

pollutes

glaciersfaster

more

groundwater

Case Study: The Aral Sea Disaster (2)

• People living in the Aral Sea watershed have experienced increasing ___________ problems due to all of the pollution• Anemia• Respiratory illnesses• Liver and kidney disease• Eye problems• Various cancers

health

Case Study: The Aral Sea Disaster (2)

• Since 1999, the United Nations and World Bank have spent about $600 million to…• _________________ drinking water• _______________ irrigation and drainage systems

• Neighboring countries have been replacing water-thirsty crops with others that require ________ irrigation

• ___________ was built to raise lake levels in the Northern Aral Sea

purifyimprove

less

Dike

13-5 Is Converting Salty Seawater to Freshwater the Answer?

• Concept 13-5 We can convert salty ocean water to freshwater, but the cost is high, and the resulting salty brine must be disposed of without harming aquatic or terrestrial ecosystems.

Removing Salt from Seawater Is Costly, Kills Organisms, Creates Briny Wastewater (1)

• Desalination - removing dissolved salts from ocean water or from _____________ (slightly salty) water in aquifers or lakes• Two most widely used methods are

________________ and _______________ osmosis

• Distillation uses… • heat to evaporate water, leaving salts ______________• Cool or ___________________ steam back into liquid

water

brackish

distillation reverse

behindcondense

Removing Salt from Seawater Is Costly, Kills Organisms, Creates Briny Wastewater (1)

• Reverse osmosis…also called _________________• Uses high ______________ to force salt water

through a membrane _____________ with pores that are small enough to remove the salt

• Currently there are about ________________ desalination plants mostly in arid areas of…• Middle east• North Africa• Caribbean• Mediterranean

microfiltration

pressurefilter

14,450

Removing Salt from Seawater Is Costly, Kills Organisms, Creates Briny Wastewater (2)

• Three major problems with the widespread use of desalination1. High __________ and energy footprint2. Chemicals are required to keep down ___________

growth…____________ many marine organisms3. Produces huge quantities of ____________ salts

that must go somewhere

Bottom Line: Currently, desalination is practical only for water _____________, _______________ countries

cost

algalkill

waste

short wealthy

Science Focus: The Search for Improved Desalination Technology

Improved desalination?• Using other forms of energy to power plants…• _____________________• _____________________• _____________________

• Using ___________ to carry desalination equipment instead of land-based desalination plants• Use water from depths ______________ where most

marine organisms live• The remaining salt or _____________ could be carried

away from the coast and ___________________

solarwindocean waves

ships

below

brinediluted

Review Questions• What are some disadvantages of transferring water?

• What are some disadvantages of using desalination methods?

inefficient

Dries other areas (ecological damage)

Pollution

High cost

High energy needs

Chemical use and salt waste