11-1 Water Resources11-1 Water ResourcesFresh Water is a very limited resource!Fresh Water is a very limited resource! Liquid fresh water for human use is even Liquid fresh water for human use is even

more limited! (comes mainly from lakes, more limited! (comes mainly from lakes, rivers, groundwater)rivers, groundwater)

71 % of Earth’s surface is water. Of this…71 % of Earth’s surface is water. Of this… 97% is salt water (oceans, seas)97% is salt water (oceans, seas) 3% fresh water. Of this…3% fresh water. Of this…

• 77% of fresh water is frozen77% of fresh water is frozen

2 Main Sources of Freshwater:2 Main Sources of Freshwater:1) 1) Surface WaterSurface Water (water on Earth’s land surface) (water on Earth’s land surface) In lakes, rivers, streams, wetlands.In lakes, rivers, streams, wetlands. Settlements (towns, cities) have been typically Settlements (towns, cities) have been typically

situated on sources of water.situated on sources of water. Used for – drinking, crops, fish, power generation, Used for – drinking, crops, fish, power generation,

transportationtransportation River SystemRiver System: flowing network of water made of : flowing network of water made of

streams and riversstreams and rivers More streams = larger riverMore streams = larger river Amount of water varies by season and year.Amount of water varies by season and year. Amazon River System is the largest in the world.Amazon River System is the largest in the world. WatershedWatershed: area of land that is drained by a river.: area of land that is drained by a river.

• Pollution anywhere in a watershed may end up polluting a river.Pollution anywhere in a watershed may end up polluting a river.

2) 2) GroundwaterGroundwater: water stored : water stored beneath Earth’s surface in sediment beneath Earth’s surface in sediment and rock formationsand rock formations

Water table: area where rocks and soil are saturated with water (the top of an aquifer) – it is NOT level

Aquifer: underground formation that contains groundwater (often made of rock, sand, gravel)

Porosity: amount of space between the particles that make up a rock (more porous rocks hold more water)Permeability: ability rock or soil to allow water to flow through it

Permeable = allows flow (gravel, sandstone, limestone, sand)Impermeable = stops the flow of water (clay, granite)

Recharge Zone: area of Earth’s surface where water enters into the aquifer

* Environmentally sensitive areas (pollution in the recharge zone could enter the aquifer)

Well: hole dug/drilled to reach groundwater•Water filtered and purified as it travels underground•height of eater table changes seasonally•if water is pumped out faster than it’s replenished, water drops (well

can go “dry”)

11-2 Water Use and Management 11-2 Water Use and Management 3 Main Types of Water Use3 Main Types of Water Use1. 1. ResidentialResidential About 14% of worldwide water useAbout 14% of worldwide water use Amount varies widely around the worldAmount varies widely around the world In U.S. about ½ is for activities inside the home In U.S. about ½ is for activities inside the home

(drinking, cooking, washing, flushing), ½ goes (drinking, cooking, washing, flushing), ½ goes to outdoor activities (lawns, washing cars)to outdoor activities (lawns, washing cars)

Water TreatmentWater Treatment• Physical and/or chemicalPhysical and/or chemical• Usually needed to make waterUsually needed to make water potablepotable (safe to drink) (safe to drink)• Removes harmful elements (mercury, arsenic, lead) andRemoves harmful elements (mercury, arsenic, lead) and

pathogenspathogens (organisms that cause illness {bacteria, (organisms that cause illness {bacteria, viruses, parasites, etc.})viruses, parasites, etc.})

2.2. Industrial Industrial 19% of worldwide water use19% of worldwide water use Manufacturing, dispose of waste, generate Manufacturing, dispose of waste, generate

power (1,000 L of water to make 1 kg of power (1,000 L of water to make 1 kg of aluminum, 500,000 L of water to make a car)aluminum, 500,000 L of water to make a car)

Most used to cool power plantsMost used to cool power plants

3. Agricultural3. Agricultural Worldwide most water use is agricultural Worldwide most water use is agricultural

(67%).(67%). Plants need a lot of water to grow (an ear of Plants need a lot of water to grow (an ear of

corn can take nearly 80 gal – about as much corn can take nearly 80 gal – about as much as you use in a day)as you use in a day)

A lot evaporatesA lot evaporates Irrigation: providing plants with water from Irrigation: providing plants with water from

sources other than direct precipitationsources other than direct precipitation

Water Management ProjectsWater Management Projects1. Water Diversion Projects1. Water Diversion Projects All or part of a river can be diverted into canals All or part of a river can be diverted into canals

that carry water across great distances to that carry water across great distances to supply dry regions with water. (The Colorado supply dry regions with water. (The Colorado River is heavily diverted to places like AZ, UT, River is heavily diverted to places like AZ, UT, CA.)CA.)

2. Dams & Reservoirs2. Dams & Reservoirsa.a. DamDam: structure built across a river to control the : structure built across a river to control the

river’s flowriver’s flowb.b. ReservoirReservoir: artificial lake that forms behind a dam: artificial lake that forms behind a dam Also used to generate electricity = Also used to generate electricity = hydroelectric hydroelectric

damdam Can be used for flood control, drinking, irrigation, Can be used for flood control, drinking, irrigation,

recreation, industryrecreation, industry Dams flood land behind them (displacing people Dams flood land behind them (displacing people

and destroying ecosystems)and destroying ecosystems) Dams slow water, dropping sediment in Dams slow water, dropping sediment in

reservoirs, robbing land downstream of nutrientsreservoirs, robbing land downstream of nutrients Dam failure can cause death or injury below the Dam failure can cause death or injury below the

damdam

Water ConservationWater Conservation1 way to ensure that everyone will 1 way to ensure that everyone will have enough water at a reasonable have enough water at a reasonable priceprice

1. 1. Agricultural Water ConservationAgricultural Water Conservation Drip irrigation systemsDrip irrigation systems: deliver small amts. Of : deliver small amts. Of

water directly to plants as needed, at a water directly to plants as needed, at a controlled rate – loses very little water to controlled rate – loses very little water to evaporation, seepage, or runoffevaporation, seepage, or runoff

2. Industrial Water Conservation2. Industrial Water Conservation Recycling cooling water and wastewaterRecycling cooling water and wastewater

3. Home Water Conservation3. Home Water Conservation Use only the water you needUse only the water you need XeriscapingXeriscaping: designing a landscape that : designing a landscape that

requires minimal water use (drought-requires minimal water use (drought-tolerant plants)tolerant plants)

Just a few things you can do to Just a few things you can do to Conserve WaterConserve Water

1.1. Take shorter showers, and avoid taking baths unless you keep Take shorter showers, and avoid taking baths unless you keep the water level low.the water level low.

2.2. Install a low-flow shower head in your shower.Install a low-flow shower head in your shower.3.3. Install inexpensive, low-flow aerators in your water faucets at Install inexpensive, low-flow aerators in your water faucets at

home.home.4.4. Purchase a modern, low-flow toilet, install a water-saving Purchase a modern, low-flow toilet, install a water-saving

device in your toilet, or simply place a water bottle (or brick) device in your toilet, or simply place a water bottle (or brick) inside your toilet tank to reduce the water used for each flush.inside your toilet tank to reduce the water used for each flush.

5.5. Don’t let the water run while you are brushing your teeth.Don’t let the water run while you are brushing your teeth.6.6. Fill up the sink basin rather than letting water run when you are Fill up the sink basin rather than letting water run when you are

shaving, or washing dishes.shaving, or washing dishes.7.7. Wash only full loads in your dishwasher and washing machineWash only full loads in your dishwasher and washing machine8.8. Water your lawn sparingly, and in the early morning or late Water your lawn sparingly, and in the early morning or late

evening to avoid evaporation evening to avoid evaporation

Solutions for the FutureSolutions for the Future As populations grow, other sources of fresh As populations grow, other sources of fresh

water need to be developed.water need to be developed. DesalinationDesalination: removing salt from salt water – : removing salt from salt water –

heat up salt water and collect the evaporation heat up salt water and collect the evaporation (consumes a lot of energy = expensive)(consumes a lot of energy = expensive)

Transporting Water Transporting Water