water resources and water pollution chapter 8 geog415

Water Resources and Water Pollution

Chapter 8

Geog415

Will We Have Enough Usable Water?

We are using available freshwater unsustainably by wasting it, polluting it, and charging too little for this irreplaceable natural resource.

One of every six people does not have sufficient access to clean water, and this situation will almost certainly get worse (one out of 4 people in 2050).

Freshwater Is an Irreplaceable Resource That We Are Managing

Poorly

water keeps us alive, moderates climate, sculpts the land, removes and dilutes wastes and pollutants, and is recycled by the hydrologic cycle

All organisms are made of mostly water (60% human body). A person could survive for several weeks without food but only a few days without water.

Earth as a watery world: 71%; Freshwater availability: 0.024%

Freshwater Is an Irreplaceable Resource That We Are Managing Poorly (2)

Hydrologic cycle • Movement of water in the seas, land, and air• Driven by solar energy and gravity

Fresh water supply is continuously collected, purified, recycled, and distributed through hydrological cycle (evaporation-condensation to clouds-precipitation-runoff or infiltration to underground-back to ocean)

But we are overloading water system by slowly degradable and nondegradable wastes or withdraw water from underground supplies faster than it is replenished.

Water is not evenly distributed:• Water haves: Canada (with 0.5% of world population has

1/5 of world’s fresh water)• Water have-nots: China (with 1/5 of the world population

has 7% of world fresh water)

We Get Freshwater from Groundwater and Surface

Water

Ground water:water stored in the pores, fractures, crevices, and other spaces in

soil and rock.

Zone of saturation: the spaces in rocks are completely filled with water.

Water table:Top of the zone of saturation

Aquifers:Porous, water-saturated layers of sand, gravel or bedrock through which

groundwater flows. One of every three people depends on water from aquifer for drinking and other uses.

Natural recharges: aquifers are replenished naturally by precipitation that percolates downward through soil and rock (3 feet per year and no more than 1 foot per day)

We Get Freshwater from Groundwater and Surface Water (2)

Surface WaterSurface runoff:Precipitation that does not infiltrate the ground or return to the

atmosphere by evaporation (flows across the earth’s land and into rivers, streams, lakes, wetlands, and estuaries).

Watershed (drainage) basin:The region from which surface water drains into a river, lake,

wetland, or other body of water.

Reliable runoff:1/3 of total run off that we can count on as a stable source of

fresh water every year

Unconfined Aquifer Recharge Area

Precipitation Evaporation and transpiration Evaporation

Confined Recharge Area

Runoff

Flowing artesian well

Well requiring a pump Stream

Infiltration

Water table Lake

InfiltrationUnconfined aquiferLess

permeable material such as clay

Confined aquiferConfining impermeable rock layer

Fig. 8-1, p. 160

Ground Water System

We Use less than Half of the World’s Reliable Runoff

2/3 of the surface runoff: lost by seasonal floods

1/3 runoff usable • Domestic: 10%• Agriculture: 70% (produce 40% of the world’s

food)• Industrial use: 20%

Freshwater Resources in the United States

More than enough renewable freshwater, unevenly distributed

Effect of• Floods• Pollution• Drought

2007: U.S. Geological Survey projection • Water hotspots

Average Annual Precipitation and Major Rivers, Water-Deficit Regions in U.S.

Ample precipitation in the east and too little in the west

In the east, largest uses for water are for energy production, cooling, and manufacturing; In the west, the largest use is for irrigation

Problem in the east is flooding, pollution, and occasional urban shortagesIn the west is the shortage of runoff caused by low precipitation, high evaporation, and recurring prolonged drought

Water Hotspots in 17 Western U.S. States

Natural Capital Degradation: Stress on the World’s Major River Basins

Core Case Study: Water Conflicts in the Middle East: A Preview of the Future

Water shortages in the Middle East: hydrological poverty

Water relies on three rivers:Nile River; Jordan Basin; Tigris and

Euphrates RiversNile: Ethiopia, Sudan plans to divert

more water from Nile that would reduce the downstream water supply in Egypt. Possible solution: (1) go to war with Sudan and Ethiopia for more water; (2) cut population growth; import more grains to reduce need for irrigation; (3) work out water-sharing agreements with other countries; (4) suffer harsh human and economic consequences of hydrology poverty

Jordan Basin is the most water-shortage region, with fierce competition for its water among Jordan, Syrian Palestine (Gaza and the West Bank), and Israel. Syria plans to build dams and withdraw more water from the Jordan river, decreasing downstream water supply for Jordan and Israel. Israel warns that they will destroy the largest dam Syria plans to build.

Turkey, located on the headwaters of Tigris and Euphrates River, controls how much water flows downstream to Syria and Iraq before empting into the Persian Gulf. Turkey is building 24 dams to generate electricity and irrigate a large area of land (will reduce water flow up to 35% or more). Syria also plans to build a large dam along the Euphrates River to diver water. This will leave little water for Iraq and could lead to a war with Syria.

Possible solution for water conflict in Middle East

regional cooperation in allocating water supplies slowed population growth Improved efficiency in water use Higher water prices to help improve irrigation efficiency Increased grain imports to reduce water needs

How Can We Increase Water Supplies?

Pumping groundwater building dams and reservoir to store runoff transferring water from other areas desalination (convert salt water to fresh )

But all create environmental problems

Groundwater Is Being Withdrawn Faster Than It Is Replenished in Some Areas

India, China, and the United States• Three largest grain producers• Overpumping aquifers for

irrigation of crops India and China

• Small farmers drilling tubewells • Effect on water table

Saudi Arabia• Aquifer depletion and irrigation

Ogallala aquifer: largest known aquifer• Irrigates the Great Plains• Water table lowered more than

30m• Cost of high pumping has

eliminated some of the farmers• Government subsidies to continue

farming deplete the aquifer further• Biodiversity threatened in some

areas

California Central Valley: serious water depletion

Coastal area, salt water intrusion in aquifers

Trade-Offs: Withdrawing Groundwater, Advantages and Disadvantages

Natural Capital Degradation: Areas of Greatest Aquifer Depletion in the U.S.

Solutions: Groundwater Depletion, Using Water More Sustainably

Large Dams and Reservoirs Have Advantages and Disadvantages

Main goals of a dam and reservoir system• Capture and store

runoff

• Release runoff as needed to control:• Floods• Generate

electricity• Supply

irrigation water• Recreation

(reservoirs)

Natural Capital: Ecological Services of Rivers

The California Water Project and the Central Arizona Project

Case Study: The Aral Sea Disaster

Large-scale water transfers (by former Soviet Union) in dry central Asia-800 miles of irrigation canal

Shrinking Aral Sea (lost 83% water volume) and increased water salinity 3 times.

Wetland destruction (85% eliminated) and wildlife (half of the bird and mammal species disappeared; 20 of the 24 native fish species extinction)

Wind-blown salt dust spread water pollution Climatic changes (summer is hotter and winter is colder) Health problem from toxic dust, salt and water

contamination

Removing Salt from Seawater

Desalination• Distillation: heating soil water until it evaporates, leaves

behind slats in solid form and condenses as fresh water

• Reverse osmosis, microfiltration: pumping salt water at high pressure through a thin membrane with pores that allows water molecules, but not most dissolved salts to pass through

Problems: high coast; produces large quantities of briny wastewater that contains salt and other minerals

Active Figure: Threats to aquifers

How Can We Use Water More Sustainably?

We can use water more sustainably if we cut water waste (1/3 water is wasted), raise water prices, slow population growth, and protect aquifers, forests, and other ecosystems that store and release water.

“The frog does not drink up the pond in which it lives”

Major Irrigation Systems

We Can Cut Water Waste in Irrigation

Human-powered treadle pumps

Harvest and store rainwater

Create a canopy over crops: reduces evaporation

Fog-catcher nets

We Can Cut Water Waste in Industry and Homes

Recycle water in industry

Fix leaks in the plumbing systems

Use water-thrifty landscaping: xeriscaping

Use gray water

Pay-as-you-go water use

Solutions: Sustainable Water Use

What Can You Do? Water Use and Waste

How Can We Reduce the Threat of Flooding?

We can improve flood control by protecting wetlands and natural vegetation in watersheds and by not building in areas subject to frequent flooding.

Some Areas Get Too Much Water from Flooding

Flood: water in stream overflows its normal channel and spills into the adjacent area (Floodplain)

Flood plains • Highly productive wetlands• Provide natural flood and erosion

control• Maintain high water quality• Recharge groundwater

Benefits of floodplains• Fertile soils• Nearby rivers for use and

recreation• Flatlands for urbanization and

farming

Dangers of floodplains and floods• Deadly and

destructive• Human activities

worsen floods• Failing dams and

water diversion• Hurricane Katrina

and the Gulf Coast• Removal of

coastal wetlands

Natural Capital Degradation: Hillside Before and After Deforestation

Case Study: Living Dangerously on Floodplains in Bangladesh

Dense population

Located on coastal floodplain

Moderate floods maintain fertile soil

Increased frequency of large floods

Effects of development in the Himalayan foothills

Destruction of coastal wetlands

We Can Reduce Flood Risks

Rely more on nature’s systems• Wetlands• Natural

vegetation in watersheds

Rely less on engineering devices• Dams• Levees

Active Figure: Effects of deforestation

What Are the Causes and Effects of Water Pollution?

Water pollution, caused mostly by agricultural activities, industrial facilities, and mining, and worsened by growth in population and resource use, causes illness and death in humans and other species and disrupts ecosystems.

Water Pollution Comes from Point and Nonpoint Sources

Water pollution: any chemical, biological, or physical change in water quality that has a harmful effect on living organisms or makes water unsuitable for desired uses

Point sources• Located at specific places• Easy to identify, monitor, and regulate• Examples: factories, sewage treatment plants, underground

mines, and oil tankers

Nonpoint sourcesBroad, diffuse areasDifficult to identify and controlExpensive to clean upExamples: atmosphere, croplands runoff, livestock feedlots, logged forests, urban streets, lawn, golf courses, parking lots.

Major Water Pollutants Have Harmful Effects

Infectious disease organisms: contaminated drinking water

The World Health Organization (WHO) • 3 Million people die every year, mostly under the

age of 5

Major Water Pollutants and Their Sources

What Are the Major Water Pollution Problems in

Streams and Lakes?

Addition of pollutants and excessive nutrients to streams and lakes can disrupt these ecosystems, and prevention of such pollution is more effective and less costly than cleaning it up.

Dilution and Decay of Degradable, Oxygen-Demanding Wastes in a Stream

Global Outlook: Stream Pollution in Developing Countries

Half of the world’s 500 rivers are polluted

Untreated sewage

Industrial waste

India’s rivers

China’s rivers

Cultural Eutrophication Is Too Much of a Good Thing

Eutrophication: natural nutrient enrichment of lakes, mostly from runoff of plant nutrients such as nitrates and phosphates from surrounding land

Cultural eutrophication: human activities greatly accelerate the input of plant nutrients to a lake. Promote growth of sense growth or bloom of organisms. These plant life reduce lake productivity by decreasing the solar energy input needed by phytoplankton that support fish. When algae dies, the bacteria depletes dissolved oxygen in the surface layer of water near the shore and in the bottom layer.

During hot weather or droughtsAlgal blooms; Increased bacteria; More nutrients; Anaerobic bacteria

Prevent or reduce cultural eutrophication• Remove nitrates and phosphates• Diversion of lake water

Clean up lakes• Remove excess weeds• Use herbicides and algaecides; down-side?• Pump in air

What Are the Major Pollution Problems Affecting Water Sources?

Chemicals used in agriculture, industry, transportation, and homes can spill and leak into groundwater and make it undrinkable; polluted water can be purified, but protecting it through pollution prevention is the least expensive and most effective strategy.

Ground Water Cannot Cleanse Itself Very Well

Source of drinking water

Common pollutants• Fertilizers and

pesticides• Gasoline• Organic solvents

Pollutants dispersed in a widening plume

Slower chemical reactions in groundwater due to• Slow flow: contaminants not

diluted • Less dissolved oxygen• Fewer decomposing bacteria

How long will it take to cleans itself of• Slowly degradable wastes

• E.g., DDT

• Nondegradable wastes• E.g., Pb and As

Principal Sources of Groundwater Contamination in the U.S.

Pollution Prevention Is the Only Effective Way to Protect Groundwater

Prevent contamination of groundwater

Cleanup: expensive and time consuming

Solutions: Groundwater Pollution, Prevention and Cleanup

Is Bottled Water the Answer?

U.S.: some of the cleanest drinking water

Bottled water• Some from tap water• 40% bacterial contamination• Fuel cost to manufacture the plastic bottles• Recycling of the plastic

Growing back-to-the-tap movement

Active Figure: Stream pollution

ABC Video: MTBE pollution

What Are the Major Water Pollution Problems Affecting Oceans?

The great majority of ocean pollution originates on land and includes oil and other toxic chemicals and solid waste, which threaten fish and wildlife and disrupt marine ecosystems; the key to protecting oceans is to reduce the flow of pollutants into coastal waters.

Ocean Pollution Is a Growing and Poorly Understood Problem

2006: State of the Marine Environment• 80% of marine

pollution originates on land

• Sewage• Coastal areas

most affected

Deeper ocean waters• Dilution• Dispersion• Degradation

Cruise line pollution: what is being dumped?

U.S. coastal waters• Raw sewage • Sewage and

agricultural runoff: NO3

- and PO43-

• Harmful algal blooms

• Oxygen-depleted zones

¼ of the people using coastal beaches in the US develop ear infection. Sore throats, eye irritations, respiratory disease, or gastrointestinal disease

Residential Areas, Factories, and Farms Contribute to Pollution of Coastal Waters

Chesapeake Bay

Ocean Oil Pollution Is a Serious Problem

Crude and refined petroleum• Highly disruptive

pollutants

Largest source of ocean oil pollution• Urban and

industrial runoff from land

1989: Exxon Valdez, oil tanker

2002: Prestige, oil tanker

Volatile organic hydrocarbons• Kill many aquatic

organisms

Tar-like globs on the ocean’s surface• Coat animals

Heavy oil components sink • Affect the bottom

dwellers

Faster recovery from crude oil than refined oil

Cleanup procedures

Methods of preventing oil spills

Solutions: Coastal Water Pollution, Prevention and Cleanup

ABC Video: Beach pollution

How Can We Best Deal with Water Pollution?

Reducing water pollution requires preventing it, working with nature in treating sewage, cutting resource use and waste, reducing poverty, and slowing population growth.

Sewage Treatment Reduces Water Pollution (1)

Septic tank system

Wastewater or sewage treatment plants• Primary sewage treatment• Physical process

• Secondary sewage treatment• Biological process

• Tertiary or advance sewage treatment • Bleaching, chlorination

Solutions: Septic Tank System

We Can Improve Conventional Sewage Treatment

Peter Montague: environmental scientist• Remove toxic wastes before water goes to the

municipal sewage treatment plants• Reduce or eliminate use and waste of toxic

chemicals• Use composting toilet systems

Wetland-based sewage treatment systems

Solutions: Primary and Secondary Sewage Treatment

Solutions: Water Pollution, Methods for Preventing and Reducing Water Pollution

What Can You Do? Water Pollution, Ways to Help Reduce Water Pollution