Best Dam Lecture Ever!!

US has 75,000 Large Dams (25 ft or higher)

• China = 80,000 DamsChina = 80,000 Dams

Colorado River Dams•Used to provide energy and water to So. Calif and

Vegas.

•Reservoir: lake formed behind

dam.

Hoover Dam

Lake MeadLake Mead

Hoover Dam

3 Gorges Dam3 Gorges Dam• Largest Dam, 1 mi.

long on Yangtze River

• Helps switch from coal hydroelectricity.

• Dislocation of 1 mill. peeps, burial of artifacts, loss of fertile soil on floodplains.

Aswan Dam, Nile River: Aswan Dam, Nile River: Creates Lake NasserCreates Lake Nasser

How this Dam Water WorksHow this Dam Water Works1)1) Water released Water released

from behind from behind reservoirreservoir

2)2) Enters DamEnters Dam3)3) Water spins a Water spins a

turbine machine turbine machine in damin dam

4)4) Turbine gens. Turbine gens. hydroelectricityhydroelectricity

5)5) Electricity Electricity delivered 2 cities delivered 2 cities via power lines. via power lines.

Glen Canyon Glen Canyon DamDam

• Supply water year round • Electrical Power

• Recreation benefits; boating

& fishing• No air pollution

• Water used for agriculture• Inexpensive electricity

• Long economic life

Dam ProsDam Pros

Dam ConsDam Cons

• Expensive to build, loss of human lives

• Sediments don’t flow downstream loss of nutrients

• Evaporation of fresh water behind dam increases salinity

• Fish can’t travel upstream.

Dam failure flood

• Increased risk of disease stagnant water (Mosquitoes and malaria)

Case Study: Steelhead/ Case Study: Steelhead/ Rainbow TroutRainbow Trout

• Born in freshwater Born in freshwater rivers (rainbow)rivers (rainbow)

• Swim out to ocean Swim out to ocean (steelhead)(steelhead)

• Return to same river Return to same river (travel upstream) to (travel upstream) to have their babies.have their babies.

• If dam is in place, If dam is in place, cannot return to cannot return to have babies have babies die die

Case Study: Columbia River• Story about fish…Story about fish…

• Fixing problemFixing problem

Fish LadderFish Ladder• Series of steps the

fish hop over to travel upstream (get over dam).

Water Water DiversionDiversion

Diverts or directs water to places in need.

(Irrigation, Drinking Water)

Exs: LA and Colorado Aqueducts

Sharing Water ResourcesSharing Water Resources

• 3/43/4 of the worlds major river of the worlds major river basins are shared bbasins are shared b//tt at least at least 22

nationsnations

• International International cooperationcooperation!!!!

• Aral Sea: In Glorious Nation of Kazakhstan

• Rivers to inland sea have been diverted for irrigation

Water Diversion DisasterWater Diversion Disaster

Case Study: Aral Sea

• Evaporation has increased salinity, no fish species exist

• Salt is blown to surrounding area health problems and decreasing crop production

Aral Sea-Was the 4Aral Sea-Was the 4thth largest largest freshwater lakefreshwater lake

19891989 20032003

And And Now, Now, 20092009

Water Water ConservationConservation

• Farmers must Farmers must heavily irrigate-heavily irrigate-water crops- so water crops- so plants can grow and plants can grow and to remove saltto remove salt

• Efficient irrigation Efficient irrigation systems exist to systems exist to lessen water: use of lessen water: use of lasers, central pivot lasers, central pivot watering systems, watering systems, timers. timers.

IrrigationIrrigation

Central Pivot Central Pivot SystemSystem

Agriculture HAgriculture H22O ConservationO Conservation

• Water crops at night (less evaporation)• Breed/select crops that are drought

tolerant• Cover surface with mulch

• Use Reclaimed Water: Treated Sewage Water: irrigate cropsirrigate crops//water water parksparks

• City Conservation Efforts: ConsumerConsumer eded.. (If it’s yellow, be (If it’s yellow, be mellow; if it’s brown, mellow; if it’s brown, flush it down)flush it down)

ReducingReducing City City Water UseWater Use

• Install low flow shower heads• Install low flush toilets

• Use dishwasher rather than by hand

• Take shorter showers (once a day, 10 mins/less)

Conserving Water at HomeConserving Water at Home

• Fix leaks

• Don’t use water to clean sidewalks

• Reduce amount of grass

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