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Water Pollution
CASE STUDY: WATER CONFLICTS
Water shortages in the Middle East
Nile River
Jordan Basin
Tigris and Euphrates Rivers
WILL WE HAVE ENOUGH WATER?We are using available freshwater unsustainably
wasting it polluting it charging too little for this irreplaceable natural
resource.
One of every six people do not have sufficient access to clean water, and this situation will
almost certainly get worse.
IMPORTANCE AND AVAILABILITY OF WATER
Why is water so important?
Earth as a watery world – 71%
Freshwater availability – 0.024%
Poorly managed resource
Hydrologic cycle
Water pollution
Confining impermeable rock layer
Less permeable material such as clay
Stream
Wellrequiringa pump Lake
Unconfined aquifer
Flowingartesian well
Runoff
ConfinedRechargeArea
Watertable
Confined aquifer
Infiltration
EvaporationEvaporation and transpiration
Infiltration
Unconfined Aquifer Recharge Area
Recharge Unconfined Aquifer
Precipitation
GROUNDWATER
Zone of saturation
Water table
Aquifers
Natural recharge
SURFACE WATER
Surface runoff
Watershed (drainage) basin
Reliable runoff – 1/3 of total
Runoff useDomestic – 10%Agriculture – 70%Industrial use – 20%
CASE STUDY: FRESHWATER RESOURCES IN THE UNITED STATES
Uneven distribution
Contamination
Eastern U.S.
Western U.S.
Groundwater withdrawal – 50%
HOW CAN WE INCREASE WATER SUPPLIES?
We can convert salty ocean water to freshwater, but the cost is high, and the
resulting salty brine must be disposed of without harming aquatic or terrestrial
ecosystems.
SALTWATER INTRUSION INTOCOASTAL WATER WELLS
ARAL SEA DISASTER
Large-scale water transfers in dry central Asia
Salinity
Wetland destruction and wildlife
Fish extinctions and fishing
ARAL SEA DISASTER
Wind-blown salt
Water pollution
Climatic changes
Restoration efforts
REMOVING SALT FROM SEAWATER
Desalination
Distillation
Reverse osmosis
15,000 plants in 125 countries
MAJOR PROBLEMS WITH DESALINATION
High costDeath of marine organismsLarge quantity of brine wastesFuture economics
Ashkelon Plant supplies 15%of Israel’s Householdswater needs-Largest plant in 2005
HOW CAN WE USE WATER MORE SUSTAINABLY?
We can use water more sustainably by cutting water waste, raising water prices,
slowing population growth, and protecting aquifers, forests, and other ecosystems that
store and release water.
REDUCING WATER WASTE (1)
Benefits of water conservation
Worldwide – 65-70% loss Evaporation, leaks
Water prices, government subsides, waste
REDUCING WATER WASTE (2)
Improve irrigation efficiency
Improve collection efficiency
Use less in homes and businesses
REDUCING IRRIGATION WATER WASTE
SUSTAINABLE WATER USE
WHAT CAN YOU DO?
HOW CAN WE REDUCE THE THREAT OF FLOODING?
We can improve flood control by protecting more wetlands and natural vegetation in watersheds and by not building in areas
subject to frequent flooding.
BENEFITS OF FLOODPLAINS (1)
Highly productive wetlands
Provide natural flood and erosion control
Maintain high water quality
Recharge groundwater
BENEFITS OF FLOODPLAINS (2)
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 CoastRemoval of coastal wetlands
BEFORE AND DURING A FLOOD INST. LOUIS, MISSOURI
CASE STUDY: FLOODPLAINS OF BANGLADESH
Dense population
Located on coastal floodplain
Moderate floods maintain fertile soil
Increase frequency of large floods
Development in the Himalayan foothills
Destruction of coastal wetlands
WATER POLLUTION SOURCES
Water pollution
Point sourcesDischarge at specific locationsEasier to identify, monitor, regulate
Nonpoint sourcesRunoff of chemicals and sedimentAgricultureControl is difficult and expensive
POLLUTION IN STREAMS
LAKE POLLUTION (1)
Dilution less effective than with streamsStratificationLow flow
Lakes are more vulnerable than streams
Eutrophication – natural aging processOligotrophic
OLIGOTROPHIC AND EUTROPHIC LAKES
GROUNDWATER POLLUTION (1)
Sources
Slow flow, dilution, dispersion
Low dissolved oxygen
Fewer bacteria
Cooler temperatures
GROUNDWATER POLLUTION (2)
Longtime scale for natural cleansingDegradable wastes – organic matterSlowly degradable wastes – DDTNondegradable wastes – lead, arsenic, fluoride
SOURCES OF GROUNDWATER POLLUTION
EXTENT OF GROUNDWATER POLLUTION
Global scale – not much known
Monitoring is very expensive
Underground fuel tank leakageMTBE
Arsenic
Protecting groundwater – prevention is best!
OCEAN POLLUTION
Coastal areas – highly productive ecosystemsOccupied by 40% of populationTwice that population by 2050About 80% marine pollution originates on land
Deep ocean watersSome capacity to dilute, disperse, degrade
pollutantsOcean dumping controversiesAssimilative capacity?
COASTAL WATER POLLUTION
OIL POLLUTION IN OCEANS
Crude and refined petroleum
Tanker accidents – Exxon Valdez
Urban and industrial runoff
EFFECTS OF OIL POLLUTION ON OCEAN ECOSYSTEMS
Volatile organic hydrocarbonsKill larvaeDestroys natural insulation and buoyancy
Heavy oilSinks and kills bottom organismsCoral reefs die
OIL CLEANUP METHODS
Current methods recover no more than 15%
Prevention is most effective methodControl runoffDouble haul tankers
PREVENTING NONPOINT SOURCE POLLUTION (1)
Mostly agricultural waste
Use vegetation to reduce soil erosion
Reduce fertilizer use
PREVENTING NONPOINT SOURCE POLLUTION (2)
Use plant buffer zones around fields and animal feedlots
Keep feedlots away from slopes, surface water and flood zones
Integrated pest management
LAWS FOR REDUCING POINT SOURCE POLLUTION
Clean Water Act
Water Quality Act
Discharge trading controversies
SEWAGE TREATMENT SYSTEMS
Rural and suburban areas – septic tank
Urban areas – wastewater treatment plantsPrimary treatment – physical processSecondary treatment – biological processChlorination – bleaching and disinfection
PRIMARY AND SECONDARY SEWAGE TREATMENT
IMPROVING SEWAGE TREATMENT
Systems that exclude hazardous waste
Nonhazardous waste substitutes
Composting toilet systems
REDUCING WATER POLLUTION FROM POINT SOURCES IN THE U.S.
Impressive achievements
Bad news – 2006 survey45% of lakes and 40% of streams too polluted for
fishing and swimmingRunoff polluting 7 of 10 riversFish caught in 1/4 of waterways unsafe to eat
SHOULD THE CLEAN WATER ACT BE STRENGTHENED?
Yes – environmentalists
No – farmers and developers
State and local officials want more discretion
DRINKING WATER QUALITYPurification of urban drinking water
Developed versus developing countries
الطالبة :عملالهومي أحمد . أمجاد
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