water: a limited resource. questions of the day: o why is water important? o what are some...
TRANSCRIPT
Water: A Limited ResourceWater: A Limited Resource
Questions of the day:Questions of the day:
o Why is water important?Why is water important?o What are some What are some properties of water (think properties of water (think chemistry)?chemistry)?
o What are the major uses What are the major uses of water?of water?
Importance of WaterImportance of Water
o CookingCookingo WashingWashingo Use large Use large
amounts for:amounts for:• AgricultureAgriculture• ManufacturingManufacturing• MiningMining• Energy productionEnergy production• Waste disposalWaste disposal
o Use of freshwater Use of freshwater is increasingis increasing
Properties of WaterProperties of Water
o Composed of 2 Hydrogen Composed of 2 Hydrogen and 1 oxygenand 1 oxygen
o Exists as solid, liquid or gasExists as solid, liquid or gaso High heat capacityHigh heat capacityo PolarPolar
• One end has (+) charge, one One end has (+) charge, one end has (-) chargeend has (-) charge
o Forms Hydrogen bond Forms Hydrogen bond between 2 water moleculesbetween 2 water molecules• H-bonds define water’s H-bonds define water’s
physical propertiesphysical properties
Properties of Properties of WaterWater
o Water is never Water is never completely completely pure in naturepure in nature
o Content of Content of seawater (left)seawater (left)
o Many Many substances substances water dissolves water dissolves cause water cause water pollutionpollution
Hydrologic CycleHydrologic Cycle
Distribution of Distribution of WaterWater
o Only 2.5% of Only 2.5% of water on earth is water on earth is freshwaterfreshwater
o 2% is in the form 2% is in the form of ice!of ice!
o Only ~0.5% of Only ~0.5% of water on earth is water on earth is available available freshwaterfreshwater
Freshwater TerminologyFreshwater Terminology
o Surface waterSurface water• Precipitation that remains on the surface and does Precipitation that remains on the surface and does
not seep into soilnot seep into soilo RunoffRunoff
• Movement of surface water to lakes, rivers, etc.Movement of surface water to lakes, rivers, etc.o Watershed (drainage basin)Watershed (drainage basin)
• Land area that delivers water into a stream or river Land area that delivers water into a stream or river systemsystem
o GroundwaterGroundwater• Freshwater under the earth’s surface stored in Freshwater under the earth’s surface stored in
aquifersaquiferso AquiferAquifer
• Underground caverns and porous layers of sand, Underground caverns and porous layers of sand, gravel and rock in which groundwater is storedgravel and rock in which groundwater is stored
Freshwater Aquifer/GroundwaterFreshwater Aquifer/Groundwater
Q of Day- To be discussed, don’t Q of Day- To be discussed, don’t need to write downneed to write down
o What are three main problems with What are three main problems with water?water?
o How much water do you think you use How much water do you think you use in one day? (In gallons)in one day? (In gallons)
Water Use and Resource Water Use and Resource ProblemsProblems
o Fall into Three CategoriesFall into Three Categories• Too much waterToo much water• Too little waterToo little water• Poor quality/contamination Poor quality/contamination
Too Much WaterToo Much Water
o FloodingFlooding• Both natural and human-inducedBoth natural and human-induced
o Modern floods are highly destructive Modern floods are highly destructive because humans:because humans:• Remove water-absorbing plant cover from Remove water-absorbing plant cover from
soilsoil• Construct buildings on floodplainsConstruct buildings on floodplains
o FloodplainFloodplain• Area bordering a river channel that has the Area bordering a river channel that has the
potential to floodpotential to flood
Coastal floodingCoastal flooding
Flooding of RiversFlooding of Rivers
Urban vs. Pre-Urban FloodplainsUrban vs. Pre-Urban Floodplains
FloodplainFloodplain
o Government restrictions on buildingGovernment restrictions on building• Levees can failLevees can fail
o Rather than Rather than rebuild levees rebuild levees adjacent to rivers, adjacent to rivers, experts suggest experts suggest allowing some allowing some flooding of flooding of floodplains during floodplains during floodsfloods• (next slide)(next slide)
Left: Left: Traditional Traditional levees levees adjacent to adjacent to riverriver
Right: Right: Suggested Suggested levee style, set levee style, set back from back from riverriver
Journey to Planet Earth Journey to Planet Earth video segments- Create this video segments- Create this table on last page of notestable on last page of notes
Too much water-Mississippi River
Too little water-Ogallalla Aquifer
Too many obstacles- Klamath River
Too little water- Aral Sea/ Salton Sea
Too Little WaterToo Little Water
o Typically found in arid landTypically found in arid lando ProblemsProblems
• DroughtDrought• Overdrawing water Overdrawing water
for irrigation for irrigation
purposespurposes• Aquifer depletionAquifer depletion
• SubsidenceSubsidence• SinkholesSinkholes
Too Little WaterToo Little Water
o Problems (continued)Problems (continued)• Saltwater IntrusionSaltwater Intrusion
Water Problems in US and Water Problems in US and CanadaCanada
o Water shortages in West and SouthwestWater shortages in West and Southwest• Water is diverted and transported via Water is diverted and transported via
aqueductsaqueducts
Water Problems in US and Canada- Water Problems in US and Canada- Surface WaterSurface Water
o Mono Lake (Eastern CA)Mono Lake (Eastern CA)• Rivers and streams that once fed this lake Rivers and streams that once fed this lake
are diverted to Los Angeles (275mi away)are diverted to Los Angeles (275mi away)• Becoming highly salineBecoming highly saline• Court ordered water diversion reductionCourt ordered water diversion reduction
o Colorado River BasinColorado River Basin• Provides water for 27-million peopleProvides water for 27-million people• Numerous dams for HydropowerNumerous dams for Hydropower• Colorado River no longer reaches oceanColorado River no longer reaches ocean
Colorado River bed in MexicoColorado River bed in Mexico
Water Problems in US and Canada-Water Problems in US and Canada-GroundwaterGroundwater
o Aquifer DepletionAquifer Depletion