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Lecture # 11 - Water Scarcity and Water Pollution

 

Water Scarcity

 

1. Water facts

  • Earth is covered by large oceans
    • 97% is salty water
    • 3% of water is fresh water
      • Two-thirds is frozen in glaciers and polar ice caps.
      • The remaining unfrozen freshwater is mainly found as groundwater
      • Only a small fraction is above ground or in the air
  • Water is a renewable resource
    • The sun evaporates the water from the lakes, oceans, and seas
      • The water is turned into rain or snow
      • The rain and snow replenishes lakes, rivers, and underground reservoirs
    • Surface water is water in a river, lake or fresh water wetland.
    • Nature - surface water is naturally replenished by precipitation
    • Humankind - water is replenish through artificial channels, reservoirs, etc.
      • Man also releases water from treated sewage and untreated sewage
    • Nature - lost through discharge to the oceans, evaporation, and underground seepage
  • Largest sources of fresh water
    • Brazil
    • Russia
    • Canada

2. Demand for water resources

  • Demand for and use of freshwater has tripled over the past half century
    • World population grew from 2.5 to 6.45 billion people
  • Experts predict that by 2025 global water needs will increase
    • 40% more required for cities
    • 20% for growing crops
  • According to UNESCO estimates, by 2030 global demands for fresh water will exceed the supply with potentially disastrous consequences
  • Demand for fresh water - only 0.5% of the fresh water is useable
    1. Agricultural - uses 69% of the useable fresh water
      • Farmers traditionally use sprinklers to disperse water to the crops
      • Water evaporates or runs off the fields
        • Water runoff is bad
        • Take fertilizers and pesticides with it
      • Extreme case
        • Soviet Union diverted river water to irrigate the cotton fields in Uzbekistan
        • This river recharges the Aral Sea
        • The Aral Sea is now half its original size and is gradually drying up
      • Technology
        • Farmers are beginning to use drip irrigation
        • Along the crops are thin pipes with small holes
        • Water gradually drips out, only wetting the soil near the plants
        • More expensive, but more efficient
      • Cost Benefit Analysis - Compare the cost of the drip irrigation to the savings in water costs
    2. Industrial - uses 15% of the useable fresh water
      • Power plants - use water for cooling or as a power source (i.e. hydroelectric plants)
      • Ore and oil refineries - use water in chemical processes
        • Water is also used in drilling
        • As drill bit drills into the earth, water cools the drill bit and also dissolves and brings up the rocks and residues to the surface
      • Manufacturing plants - use water as a solvent.
    3. Household - uses 15% of the useable fresh water
      • Drinking water, bathing, cooking, sanitation, and gardening.
        • Government purifies water to a standard and the same water is used for households and industries
      • Government especially in dry regions are using brown water
        • Waste water is minimally cleaned and then shipped to agricultural producers
        • Requires more infrastructure
        • Separate water lines for this water
        • Charge a cheaper price
    4. Recreational - fresh water is not consumed.
      • People use water for swimming, boating, fishing, etc.
      • Demand for water can be indirect
        • People play golf
        • Golf courses use lots of water to keep grass healthy and green
    5. Environmental activities - fresh water is not consumed
      • Government builds an artificial lake
      • Lake helps a species thrive that may be going extinct

3. Desalination - a manmade process to convert saline water (i.e. sea water) to fresh water.

  • Three sources
    1. Distillation - evaporate the water and cool it into a liquid
      • Expensive - use heat to evaporate water
        • Evaporated water leaves the salts behind
        • Heat sources are natural gas, coal, solar, etc.
        • Cool the water, converting it to a liquid again
      • Not used often
    2. Reverse osmosis pass water through a permeable membrane
      • Membrane allows water to pass, but the salts remain behind.
      • Output has two water streams
        • First water stream is purified water
        • Second water steam is more concentrated salty water
      • Expensive
      • Gulf states use this method to purify water
        • Petroleum rich countries have money
          • Arid climates
        • Resorts in Western Mexico
        • St. Petersburg, Florida
          • Florida is surrounded by salt water
          • As government and people pump fresh water out of ground
            • Salt water steeps into the wells
            • Florida has been dry seasons
            • Rain and storms replenishes the ground water
      • San Diego, California - is extremely dry in Southern California
        • Having fresh water problems
        • Government has a process to convert waste water into drinking water
          • "From the toilet to the drinking fountain"
          • Resistance from public
    3. Glaciers are a source of fresh water
      • Salt lowers the freezing point of water
      • Not currently utilized

3. Urbanization - people in many countries especially developing countries are flocking to the cities

  • Government usually owns the infrastructure for fresh and waste water
    • Requires extensive infrastructure
      • Pipes for both waste and fresh water, possibly more for different water quality levels
      • Purification plants for fresh water
      • Water treatment facilities to treat sewage water
    • Customers usually pay a small portion of the costs
      • Government uses other tax revenue sources to subsidize this infrastructure
  • Urbanization
    • Cities have to expand their infrastructure
    • Government usually pumps water from the ground
    • In many places, government is pumping more water out than the amount that nature replenishes
      • Hotelling's Rule - resource is being depleted
        • Costs for water is going up
        • Governments are drilling deeper wells
        • Government is building more wells further from the city, then pump the water to the city

4. Drinkable water - water is treated to remove harmful metals and substances

  • Environmental Protection Agency regulates drinking water
    • Estimates of cost of compliance:
      • EPA estimates its cost of compliance is $1.4 billion
      • The American Water Works Association (a group of major private suppliers of drinking water) estimates the regulations costs more than $4 billion.
    • Why did EPA take over
      • Imposes uniform standards on all water companies
      • Unfortunately water quality greatly differs across the United States
        • Costs differ for different water companies
      • In the 1960s, 130 outbreaks of waterborne diseases were reported.
        • Local communities were negligent
        • Local communities were not keeping up with technology
      • EPA usually does not pay for anything
        • EPA forces local communities to pay for upgrades, etc.
  • Economics
    • United States and many countries install water meters
      • Customers pay a rate charge
      • Some claim the rates are set too low in the United States, because governments subsidizes water prices with other tax revenues
    • Indirectly the demand for water creates wastewater as a derived demand
      • We really do not a meter for wastewater
      • Quantity of wastewater <= quantity of freshwater
        • Need one meter
        • Usually the water bill has wastewater and fresh water charges separated out
        • Quantity is determined by water used by freshwater meter
    • Some parts of the United States are arid and fresh water is becoming scarce
      • Southern California, mid-West, and Florida
      • Many governments resorted to complicated rules and then fine violators
        • Special days to wash your car
        • Many people with homes and businesses have landscaping
          • Not allowed to water your plants between 6 AM and PM
      • It would be simpler to raise water rates
        • Law of Demand - consumers use less water when prices are higher

Water Pollution

 

Water pollution - substances, wastes, or chemicals dumped into water that harms the life that thrive off that source

1. Point source - pollution has an identifiable source

  1. Discharge from a sewage treatment plant
    • Sewage treatment plant - collects waste water from a city and treats it before released back into environment
    • Sewage water - 99% water and 1% organic wastes
    • Treatment plant can remove 90% of these wastes
      • People, businesses and governments dump sewage, sludge, garbage, and even toxic pollutants into water
      • Usually cannot handle industrial wastes
    • Cleaning waste water creates sludge
      • Sludge is taken to landfills, spread out on land, incinerated, or dumped at sea.
    • Treatment plants - usually owned by local government
      • Water utilities may be bureaucratic, inefficient, and corrupt.
        • Privatization may be just as bad, since they have monopoly power.
    • 90% of sewage in developing countries is discharged without treatment.
      • Why?
        • Infrastructure costs are high.
        • The price of water is subsidized in developed countries
        • Developed countries collect other tax revenue to help subsidize infrastructure
  2. Factory - discharges wastes water through a pipe into a river, lake, or ocean.
    • Developed countries - required to treat their wastes if local treatment plant cannot handle it
    • Developing countries - dump it into ponds, lakes, rivers, or oceans.
  3. City storm drains
    • When it rains on a city, a city has a system that collects the rainfall
    • The rain water picks up chemicals, oils, etc. and takes it with them
    • Developed countries - water from storm drains are treated with waste water
    • Developing countries - water may be directly discharged directly into a lake, river, or ocean.
    • Could be considered a nonpoint
      • However, the city's system collects the water and now it becomes a point source.
  4. Livestock and poultry farms
    • Developed countries - the run off from animals wastes are collected into a lagoon.
      • Wastes mixed with water is called an animal slurry
        • Slurry is applied to grasslands
      • Wastes are mixed with straw
        • Once wastes finish decomposing, then the organic material is sold to gardeners and farmers
    • If runoff from animals wastes end up in a river or lake, it kills the life in the water
      • Bacteria break down the wastes into organic substances
      • Bacteria suck the oxygen out of the water, killing off the fish and other life forms
      • Red tide - dead spots out in the Gulf of Mexico
        • All rivers feed into the Mississippi River in the Midwest United States
        • Very large spots in the ocean are dead and the bacteria makes the water a reddish color.
        • The water has no oxygen to support life
  5. Corrections
    • Usually government imposes command and control regulations
    • A permit system does exist
      • Rarely used and not popular

2. Nonpoint source - pollution does not have any identifiable source

  • Water runoff from farmers' fields
    • Rainwater collects a variety of chemicals
      • Nitrogen from manure
      • Phosphorous from fertilizers
    • Both lead to alga growth
      • Sunlight does not reach the bottom of the lake, ocean, or river, so underwater plant life dies off
      • Impacts the ecosystem
    • Rainwater may also collect pesticides and other chemicals
  • Corrections
    • Government usually imposes command and control regulations
    • Farmers build riparian buffers
      • Riparian buffer - plant trees and fields around the irrigation ditches
      • As rainwater washes off the field, it is trapped in riparian buffer and does not flow into irrigation ditches
    • Proposed permit system
      • Very difficult to monitor
 

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