chapter 13 water: a limited resource. overview of chapter 13 importance of water hydrologic cycle...
TRANSCRIPT
Chapter 13Water: A Limited Resource
Overview of Chapter 13Importance of Water
Hydrologic CycleWater Use and Resource Problems
Too Much WaterToo Little Water
Water Problems in US and CanadaGlobal Water Problems
Sharing Water ResourcesWater Management
Providing Sustainable Water SupplyWater Conservation
Importance of WaterCookingWashingUse large amounts
for:AgricultureManufacturingMiningEnergy productionWaste disposal
Use of freshwater is increasing
Properties of WaterComposed of 2 Hydrogen and 1
oxygenExists as solid, liquid or gasHigh heat capacity – absorbs a lot
of solar energy without increasing in temperature much.
Earth’s temperature matches temperature for water as a liquid.
“universal solvent” allows dissolved gases and minerals in water, including pollutants
Colder water is more dense until 4 Celsius, then becomes less dense (ice floats and allows living things beneath)
Hydrologic Cycle
Distribution of Water
Only 2.5% of water on earth is freshwater
2% is ice!Only ~0.5% of
water on earth is available freshwater
Check for understanding4 - I can explain to my peers at least 5
properties of water and how water is distributed on earth.
3 - I understand 3-4 properties of water and how water is distributed on earth.
2 - I can explain at least 2 properties of water and how water is distributed on earth.
1 - huh? I know 1 property of water.
Freshwater TerminologySurface water
Precipitation that remains on the surface and does not seep into soil
RunoffMovement of surface water to lakes, rivers, etc.
Watershed (drainage basin)Land area that delivers water into a stream or
river systemGroundwater
Freshwater under the earth’s surface stored in aquifers
AquiferUnderground caverns and porous layers of sand,
gravel and rock in which groundwater is storedUnconfined and confined (artesian)Water table
Freshwater Aquifer
Check for understanding4 - I can explain to my peers the difference between
a confined and unconfined aquifer, what a water table is and the difference between groundwater, surface water, runoff, and a watershed is.
3 - I understand the difference between a confined and unconfined aquifer, but might not fully understand the difference in one of the following terms: a water table, groundwater, surface water, runoff, and watershed
2 - I am confused about at least 2 of the above terms
1 - I am confused about at least 3 of the above terms
Water Use and Resource ProblemsFall into Three Categories
Too much waterToo little waterPoor quality/contamination (discussed later)
Water UseMostly for irrigation for agriculture: 68%
Even arid (deserts) & semiarid land grow crops with enough H2O
Asia uses mostIndustryDomestic/municipal: 8.6%
xeriscaping
Too Much WaterFlooding
Both natural and human-induced. Causes???Modern floods are highly destructive because
humans:Remove water-absorbing plant cover from soilConstruct buildings on floodplains
FloodplainArea bordering a river channel that has the
potential to floodNaturally leave behind organic matter in soil – good.
Flood consequences???
Urban vs. Pre-Urban Floodplains
FloodplainGovernment restrictions on building
Levees can fail
o Rather than rebuild levees adjacent to rivers, experts suggest allowing some flooding of floodplains during floodso Less damage if
floodedo Replenish soilo Save money
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
NEW ORLEANS: HURRICANE KATRINA: AUGUST 2005
Case-In-Point Floods of 1993: Mississippi River
Worsened due to:1.Draining wetlands for farms and homes
2. Building levees (can force more surge upstream)
3. Building on floodplains
Similar to New Orleans
Check for understanding4 - I can explain to my peers the causes and
consequences of flooding and the problems associated with flooding and why modern societies suffer more damage from them.
3 - I understand the causes and consequences of flooding and the problems associated with flooding and why modern societies suffer more damage from them
2 - I need to reread my notes, but I understand
1 - I don’t fully understand flooding.
Too Little WaterTypically found in arid land (40% of population
– Africa/Asia)Women may walk to get water instead of school
ProblemsDroughtRemove native water absorbing plants and
replace with crops/livestock overgraze more runoff, less water in soil
Overdrawing water for irrigation purposes saltier estuaries, dried
wetlands (loss of bird breeding grounds)
Too Little WaterProblems (continued)
Aquifer depletionSubsidence – sinking of land on porous rock Sinkholes – eroded limestoneSaltwater Intrusion (coasts)
Saltwater Intrusion (coasts)
Problems (continued)Aquifer depletion
Water Problems In US
US has a plentiful supply of freshwater
Many areas have a severe shortagesGeographical
variationsSeasonal
variations
Water Problems in USWater shortages in West and Southwest
Historically for irrigation, now more water for industrial and municipals due to increased population
Water is diverted and transported via aqueducts
Water Problems in US Surface Water
Mono Lake (Eastern CA)Rivers and streams that once fed this lake are
diverted to Los Angeles (275mi away)Becoming highly saline due to water diversion
disrupt food chainCourt ordered water diversion reductionLA efforts to use more reclaimed water
Colorado River BasinProvides water for 27-million people –
Colorado, California, Arizona, into MexicoNumerous dams for Hydropower; also create
resevoirsColorado River no longer reaches ocean
HOOVER DAM: BETWEEN ARIZONA AND NEVADA
SALMON FISH LADDER
Colorado River bed in Mexico
Check for understanding4 - I can explain to my peers how water
diversion and dams can disrupt the amount of water in effected areas.
3 - I understand how water diversion and dams can disrupt the amount of water in effected areas
2 - I need to reread my notes, but I understand
1 - I don’t fully understand the impact of water diversion projects and dams.
Water Problems in US and -GroundwaterAquifer Depletion – especially Arizona,
California, High Plains
Case study: Ogallala AquiferHigh PlainsLargest groundwater in
worldUses 30% of irrigation
water in US – corn, wheat, soybean, livestock (6% of land)
Water table down 100 ft in some areas (rate of recharge less than rate of extraction) cost money to deepen wells, lose $ on dead crops
Global Water ProblemsAmount of freshwater on planet CAN meet
human needsBUT, it is unevenly distributed and some
places lack stable runoff
Global Water Problems
1. Water and Climate ChangeClimate change affects the type and distribution
of precipitationPotential issues:
Reduced snowfall will impact water resources downstream
Sea level rise will cause saltwater intrusion into drinking water supplies
Global Water Problems2. Drinking Water Problems
Many developing countries have insufficient water to meet drinking and household needs (1.1 billion lack safe water, 2.6 billion no good disposal of wastewater/fecal waste) illness Ex: CholeraEx: Sahel region of AfricaHelp: World Bank, US
Agency for International Development (AID)
3. Population GrowthIncrease in population means an increase in
freshwater requirementsLimits drinking water availableLimits water available for agriculture (food)Ex: Northern China – Yellow River, Indus
River in Pakistan, Mexico (aquifer)
Global Water Problems
4. Sharing Water Resources Among CountriesRhine River Basin (right)
Countries upstream discharged pollutants into river
Countries downstream had to pay to clean the water before they could drink it
Aral SeaKazakhstan and surrounding
countriesWater diversion for irrigation
has caused sea to become too saline decreased biodiversity
Aral Sea
19671967 19971997
Check for understanding4 - I can explain to my peers how climate
change, pathogens, a growing population, and water diversion can reduce water availability.
3 - I understand how climate change, pathogens, a growing population, and water diversion can reduce water availability
2 - I need to reread my notes, but I understand
1 - I don’t fully understand the impact of climate change, pathogens, a growing population, and water diversion can have on water availability.
Global Water Problems5. Potentially Volatile
International Water SituationsJordan River – supplies
many middle Eastern countries
Nile River (NE Africa) – Sudan and Ethiopia using more (increased population) and affecting Egypt’s supply
Water Management
FUN FACT: For every kilogram of animal protein produced, livestock are fed nearly 6 kg of plant protein. Every kilogram of beef produced takes 100,000 liters of water. A kilogram of wheat requires 900 liters of water.
Water ManagementMain Goal: Provide sustainable supply of
high-quality waterRequires humans to use resource carefullyDams and ReservoirsWater Diversion ProjectsDesalinization
THREE GORGES DAM - CHINA
Dams and ReservoirsBenefits:
Ensure year-round supply of water with regulated flow
Generate electricityProvide recreational
activitiesDisadvantages
Alter the ecosystem Reduce sediment load
downstreamDisplace humansDisrupt salmon migration for
breeding
Dams and ReservoirsGlen Canyon Dam
Regulated flow has changed ecosystemTo rectify situation
Canyon has been flooded several timesSmall floods compared to natural floodsStill helps rebuild habitat
Water Diversion ProjectsDiverting water via
aquaducts/canalsEx: Mono Lake, Aral
SeaControversial and
expensive
ARAL SEA: Kazakhstan-Uzbekistan border
DesalinizationRemoval of salt from ocean or brackish
waterTwo methods:
Distillation- salt water is evaporated, and water vapor is condensed into freshwater (salt left behind)
Reverse Osmosis- involves forcing salt water through a membrane permeable to water, but not salt
Very expensive due to large energy inputWhat to do with left over salt?
Check for understanding4 - I can explain to my peers how
dams/reservoirs, desalinization, and water diversion makes water available for human use and the consequences of each.
3 - I understand how dams/reservoirs, desalinization, and water diversion makes water available for human use and the consequences of each
2 - I need to reread my notes, but I understand 1 - I don’t fully understand how dams/reservoirs,
desalinization, and water diversion makes water available for human use and the consequences of each
Water ConservationReducing Agricultural Water Waste
Drip Irrigation- irrigation that conserves water by piping to
crops through sealed systemsAlso called microirrigation or trickle irrigation
Water ConservationReducing Industrial Water Waste
EX: paper, petroleum, food processing
Stricter laws (and enforcement of those laws) provide incentive to conserve waterEX: Recycling water within the plant
Water scarcity (in addition to stricter pollution control requirements) will encourage further industrial recycling
Potential to conserve water is huge!
Water Conservation
Reducing Municipal Water Waste : reduce, reuse, recycle
Gray Water (reclaimed water)Can be used to flush
toilets, wash car or water lawn
Water saving household fixtures
Raising costs to reflect real cost
Government incentives
Conserving at HomeInstall water-saving
shower heads and faucetsInstall low-flush toiletsFix leaky fixturesPurchase high efficiency
appliances – dishwasher/washing machine
Modify personal habitsShorter showers, showers
not bathsUse the dishwasher
instead of washing by hand
Check for understanding4 - I can explain to my peers ways for
agriculture, industry, and homes can conserve water.
3 - I understand ways for agriculture, industry, and homes can conserve water
2 - I need to reread my notes, but I understand
1 - I don’t fully understand ways for agriculture, industry, and homes can conserve water.