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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
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
- 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
- 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.
- 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
- 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
- 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
- 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
- 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
- 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
- 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
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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
- 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
- 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.
- 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.
- 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
- 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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