DIHYDROGEN OXIDE!!!!

Read your info sheet

SustainabilityMake a list of things you want to see last beyond your lifetime.

These are the things you want to SUSTAIN throughout time.

Can you make some categories?

EnvironmentSocial equityEconomic

Can you make a definition of

sustainability?

Water!Miller Chapter 14

Water ResourcesWater is a “renewable” but finite

resourceClean water is essential to

human/animal health – humans can only live about 3 days without water

THIRST

“Water Planet”About 70% of Earth’s surface is

water97.5% of that is ocean water2.5% is fresh water

1.5% is frozen in ice caps & glaciers0.5% is inaccessible/brackish

Only about 0.02% of the Earth’s water supply is available as liquid freshwater

“Water Planet”

Who is using Earth’s water resources?

What 2 conclusions

can you draw from this data?

Hydrological Cycle

Hydrological CycleTranspiration – from plantsEvaporation – from rivers, lakes,

ponds, oceansPrecipitation – rainRunoff – to rivers, lakes, etcInfiltration/Seepage – to aquifers,

groundwater, to rivers & oceans, to plants

Surface WaterSurface water is

water that is above ground in lakes, rivers, ponds, and streams

A watershed is the entire area of land that is drained by a river

Fig. 14-3, p. 308

Unconfined Aquifer Recharge Area

Precipitation Evaporation and transpirationEvaporation

Confined Recharge Area

Runoff

Flowing artesian well

Recharge Unconfined Aquifer

Stream Well requiring a pump

Infiltration Water table Lak

eInfiltrationUnconfined aquiferConfined aquiferConfining impermeable rock layer

Less permeable material such as clay

Groundwater and Aquifers

Groundwater – water that seeps down into the soil and is stored underground

Aquifers – large amounts of water in underground rock formationsEx. Edward’s Aquifer (TX)

AquifersAquifers are running low – people are

pumping too much out!It can take millions of years to formRecharge zone: area of land from

which groundwater originates

Surface Water UsesWe currently use more than half of

the world’s reliable runoff of surface water and could be using 70-90% by 2025.

About 70% of the water we withdraw from rivers, lakes, and aquifers is not returned to these sources.

Irrigation is the biggest user of water (70%), followed by industries (20%) and cities and residences (10%).

Stress on the World’s River Basins

Comparison of the amount of water available with the amount used by humans.

Figure 14-6

Why is there a shortage?

Total Water Use

Freshwater Resources in the United States

17 western states by 2025 could face intense conflict over scarce water needed for urban growth, irrigation, recreation and wildlife.

Figure 14-5

Too little freshwaterAbout 41% of the world’s

population lives in river basins that do not have enough freshwater.

Many parts of the world are experiencing:Rivers running dry.Lakes and seas shrinking.Falling water tables from

overpumped aquifers.

Too little freshwaterCities are outbidding farmers for

water supplies from rivers and aquifers.

Countries are importing grain as a way to reduce their water use.

More crops are being used to produce biofuels.

Our water options are:Get more water from aquifers and

rivers, desalinate ocean water, waste less water.

Withdrawing groundwater to increase

suppliesMost aquifers are renewable

resources unless water is removed faster than it is replenished or if they are contaminated.

Groundwater depletion is a growing problem mostly from irrigation.At least one-fourth of the farms in

India are being irrigated from overpumped aquifers.

Fig. 14-7, p. 313

Trade-OffsWithdrawing Groundwater

Advantages Disadvantages

Useful for drinking and irrigation

Aquifer depletion from overpumping

Available year-round

Sinking of land (subsidence) from overpumping

Exists almost everywhere Polluted aquifers for

decades or centuriesRenewable if not overpumped or contaminated

Saltwater intrusion into drinking water supplies near coastal areasReduced water flows into surface waters

No evaporation losses

Cheaper to extract than most surface waters

Increased cost and contamination from deeper wells

Groundwater Depletion: A Growing Problem

Areas of greatest aquifer depletion from groundwater overdraft in the continental U.S.

Figure 14-8

Other Effects of Groundwater Overpumping

Groundwater overpumping can cause land to sink, and contaminate freshwater aquifers near coastal areas with saltwater.

Other Effects of Groundwater Overpumping

Sinkholes form when the roof of an underground cavern collapses after being drained of groundwater.

Figure 14-10

Fig. 14-12, p. 316

SolutionsGroundwater Depletion

Prevention Control Waste less water Raise price of

water to discourage wasteSubsidize water

conservation

Ban new wells in aquifers near surface waters

Tax water pumped from wells near surface waters

Buy and retire groundwater withdrawal rights in critical areasDo not grow water-intensive crops in dry areas

Set and enforce minimum stream flow levels

DamsDams collect

water and forms a reservoir (artificial lake)

Reservoir water is used for drinking, manufacturing, irrigation

Dams, ContinuedUsed for power and electricityDams also cause environmental

problems: when built, dry land behind dam is now flooded (destroys existing ecosystem); ecosystems downstream are disrupted due to lack of water

Provides water for year-round irrigation of cropland

Flooded land destroys forests or cropland and displaces people

Large losses of water through evaporationProvides

water for drinking Downstream

cropland and estuaries are deprived of nutrient-rich silt

Reservoir is useful for recreation and fishing

Risk of failure and devastating downstream flooding

Can produce cheap electricity (hydropower)Downstream flooding is reduced Migration and

spawning of some fish are disrupted

Fig. 14-13b, p. 317

Powerlines

Reservoir

Dam Powerhous

eIntakeTurbine

The Colorado Basin – an Overtapped Resource

The Colorado River has so many dams and withdrawals that it often does not reach the ocean.14 major dams and reservoirs, and

canals.Water is mostly used in desert area of the

U.S.Provides electricity from hydroelectric

plants for 30 million people (1/10th of the U.S. population).

The Colorado Basin – an Overtapped Resource

Lake Powell, is the second largest reservoir in the U.S.

It hosts one of the hydroelectric plants located on the Colorado River. Figure 14-15

The Colorado River Basin The area

drained by this basin is equal to more than one-twelfth of the land area of the lower 48 states.

Figure 14-14

How Would You Vote?Do the advantages of large dams

outweigh their disadvantages?a. No. Large dams inflict extensive

environmental damage and humans must learn to meet their needs without them.

b. Yes. Dams are critical in providing water and electricity for people, especially in developing countries.

Case Study: China’s Three Gorges

DamThere is a debate over whether the

advantages of the world’s largest dam and reservoir will outweigh its disadvantages.The dam will be 2 kilometers long.The electric output will be that of 18 large

coal-burning or nuclear power plants.It will facilitate ship travel reducing

transportation costs.Dam will displace 1.2 million people.Dam is built over seismatic fault and

already has small cracks.

Dam RemovalSome dams are being removed for

ecological reasons and because they have outlived their usefulness.In 1998 the U.S. Army Corps of Engineers

announced that it would no longer build large dams and diversion projects in the U.S.

The Federal Energy Regulatory Commission has approved the removal of nearly 500 dams.

Removing dams can reestablish ecosystems, but can also re-release toxicants into the environment.

Transferring water from one place to another

Transferring water can make unproductive areas more productive but can cause environmental harm.Promotes investment, jobs and

strong economy.It encourages unsustainable use of

water in areas water is not naturally supplied.

The Aral Sea DisasterThe Aral Sea was once the

world’s fourth largest freshwater lake.

Figure 14-17

The Aral Sea DisasterDiverting water from the Aral Sea and

its two feeder rivers mostly for irrigation has created a major ecological, economic, and health disaster.About 85% of the wetlands have been

eliminated and roughly 50% of the local bird and mammal species have disappeared.

Since 1961, the sea’s salinity has tripled and the water has dropped by 22 meters most likely causing 20 of the 24 native fish species to go extinct.

Solutions to water shortages

Removing salt from seawater by current methods is expensive and produces large amounts of salty wastewater that must be disposed of safely.

2 Options to “desalt” the sea:DistillationReverse osmosis

DistillationHeating

saltwater until it evaporates, leaves behind water in solid form.

Desert biomes use this method

Reverse Osmosisuses high

pressure to force saltwater through a membrane filter

salt cannot pass through

Other options“Towing

Water” - Transportation of icebergs

Problem: they melt too quickly; can’t get ashore

Other optionsSeeding clouds with tiny

particles of chemicals to increase rainfall

Huge bags filled with freshwater to dry coastal areas

All are unlikely to provide significant amounts of freshwater.

Increasing water supplies by wasting less water

We waste about two-thirds of the water we use, but we could cut this waste to 15%.65-70% of the water people use

throughout the world is lost through evaporation, leaks, and other losses.

Water is underpriced through government subsidies.

The lack of government subsidies for improving the efficiency of water use contributes to water waste.

How Would You Vote?Should water prices be raised

sharply to help reduce water waste?a. No. Poor people, farmers,

ranchers, and small businesses would suffer from price increases.

b. Yes. People would be more likely to conserve water if it is more expensive.

Increasing water supplies by wasting less water

Sixty percent of the world’s irrigation water is currently wasted, but improved irrigation techniques could cut this waste to 5-20%.

Center-pivot, low pressure sprinklers sprays water directly onto crop.It allows 80% of water to reach

crop.Has reduced depletion of Ogallala

aquifer in Texas High Plains by 30%.

Fig. 14-18, p. 325

Center pivot

Drip irrigation

Gravity flow(efficiency 60%

and 80% with surge valves)

Above- or below-ground pipes or tubes deliver water to individual plant roots.

Water usually comes from an aqueduct system or a nearby river.

(efficiency 90–95%)

(efficiency 80%–95%)Water usually pumped from underground and sprayed from mobile boom with sprinklers.

Fig. 14-19, p. 326

Solutions

Reducing Irrigation Water Waste

• Line canals bringing water to irrigation ditches• Level fields with lasers• Irrigate at night to reduce evaporation• Monitor soil moisture to add water only when necessary• Polyculture• Organic farming• Don't grow water-thirsty crops in dry areas• Grow water-efficient crops using drought resistant and salt-tolerant crop varieties• Irrigate with treated urban waste water• Import water-intensive crops and meat

Fig. 14-21, p. 327

SolutionsReducing Water Waste

• Redesign manufacturing processes• Repair leaking underground pipes• Landscape yards with plants that require little water

• Use drip irrigation• Fix water leaks• Use water meters• Raise water prices• Use waterless composting toilets• Require water conservation in water-short cities

• Use water-saving toilets, showerheads, and front loading clothes washers• Collect and reuse household water to

irrigate lawns and nonedible plants• Purify and reuse water for houses, apartments, and office buildings

• Don't waste energy

Raising the Price of Water

We can reduce water use and waste by raising the price of water while providing low lifeline rates for the poor.When Boulder, Colorado introduced

water meters, water use per person dropped by 40%.

A 10% increase in water prices cuts domestic water use by 3-7%.

Solutions: Using Less Water to Remove Industrial and

Household WastesWe can mimic the way nature

deals with wastes instead of using large amounts of high-quality water to wash away and dilute industrial and animal wastes.Use nutrients in wastewater before

treatment as soil fertilizer.Use waterless and odorless

composting toilets that convert human fecal matter into a small amount of soil material.

Too much waterHeavy rainfall, rapid snowmelt,

removal of vegetation, and destruction of wetlands cause flooding.

Floodplains, which usually include highly productive wetlands, help provide natural flood and erosion control, maintain high water quality, and recharge groundwater.

To minimize floods, rivers have been narrowed with levees and walls, and dammed to store water.

Too much waterComparison of St. Louis, Missouri

under normal conditions (1988) and after severe flooding (1993).

Figure 14-22

Too much waterHuman activities have

contributed to flood deaths and damages.

Figure 14-23

Fig. 14-24, p. 331

Solutions

Reducing Flood Damage

Prevention Control

Preserve forests on watersheds

Strengthen and deepen streams (channelization)

Preserve and restore wetlands in floodplains

Tax all development on floodplains

Build levees or floodwalls along streams

Use floodplains primarily for recharging aquifers, sustainable agriculture and forestry, and recreation

Build dams

Solutions: using water more sustainably

We can use water more sustainably by cutting waste, raising water prices, preserving forests and wetlands in water basins, and slowing population growth.

Figure 14-25

Water ConservationThough water is

recycled, the amount of usable water at any given time is limited

What kinds of things can YOU do?

What causes water shortages?

IndustrializationHuman population explosionWhat else?

Who owns the oceans?Agenda:THIRST “video”Water scarcity article share-outTragedy of the CommonsChalk Talk (http://

www.youtube.com/watch?v=KZDjPnzoge0)

Bottled v. Tap Water

SOCIAL EQUITYENVIRONMENTECONOMIC