Water Management

1
Water Management

• Chapter 16

2
The Water Issue

• 70 of earths surface is covered by water.
• Of earths freshwater (3 of total), only a tiny
  fraction is available for use.
• Potable Unpolluted, fresh water, suitable for
  drinking.
• Shortages human-induced

3
The Water Issue

• WHO - 25 of world population does not have
  access to safe drinking water.
• United Nations study (2002) - 2025 one in three
  people will have shortages.

4
The Hydrologic Cycle
5
Hydrologic Cycle

• Evaporation - Solar energy heats water.
• Evapotranspiration - Plants giving off water.
• Warm, moist air rises, cools, condenses, and
  falls as precipitation.
• Some precipitation remains on the surface and
  evaporates, while most sinks into the soil or
  returns to the oceans.
• Runoff - Surface water that moves across the
  surface of the land and enters streams and
  rivers.
• Groundwater - Water that fills spaces in the
  substrate.
• Water entering the soil is either taken up by
  plants roots or moves downward until it reaches
  an impervious layer of rock, and accumulates in
  porous strata called an aquifer.

6
Human Influences on The Hydrologic Cycle

• Runoff and infiltration rate are greatly
  influenced by human activity.
• Major concern in many urban areas is
  transportation of storm water.
• Water Withdrawal - Withdrawing water and
  returning it to its original source.
• Water Consumption - Withdrawing water and
  incorporating it into a product, or otherwise
  moving it to another area, so it does not make it
  back to original source.

7
Aquifers

• Aquifer - Porous soil saturated with water.
• Unconfined Aquifer
• near lands surface.
• Lower boundary
• impermeable layer clay /rock.
• recharged by rainfall and percolation.
• Water Table - Top layer.
• Confined Aquifer - (Artesian)
• Bounded on top and bottom by impermeable layer.
• Water stored under high pressure and recharged
  from a geologic recharge zone.
• Porosity - Measure of size and number of spaces
  in the substrate.

8
Aquifers and Groundwater
9
Kinds of Water Use

• Domestic Water Use
• Over 90 of water used for domestic purposes in
  North America is supplied by municipal water
  systems.
• Average person in a North American home uses
  about 400 liters of water per day.
• 69 used as solvent to carry wastes.
• 29 used for lawn and garden.
• 2 used for drinking or cooking.
• Natural processes cant cope w/concentrated
  urban waste.
• In US, more than thirty-six states expect a water
  crisis soon. Fast-growing western cities are
  especially vulnerable.
• Public attitude has been major force working
  against water conservation. As long as water is a
  considered limitless, inexpensive resource, few
  conservation measures occur.

10
Urban Domestic Water Uses
11
Water Use Trends Us vs other countries
12
Agricultural Water Use

• In North America, groundwater accounts for about
  37 of water used in agriculture and surface
  water accounts for about 63.
• Irrigation is the major consumptive use of water
  in most parts of the world.
• Accounts for about 80 of all water consumed in
  North America.
• Four common irrigation methods
• Surface / Flood - Requires extensive canal
  systems.
• Spray -Mandates use of pumps.
• Trickle -Strategically placed openings.
• Sub-Irrigation -Pipes can be used for drainage as
  well.

13
Agricultural Water Use

• Costs for irrigation water have traditionally
  been low since many dams and canals were built
  with federal assistance.
• Can reduce demand for irrigation water by
  reducing the quantity of water-demanding crops
  grown in dry areas.

14
Industrial Water Use

• Accounts for nearly 50 of all water withdrawal
  in U.S., and 23 worldwide.
• 90 of water used by industry is for cooling, and
  is returned to the source.
• Very little actually consumed.
• Most processes involve heat exchange.
• Water used to dissipate and transport waste.
• Stream and lake degradation.
• Clean Water Act (1972) seeks to protect U.S.
  waters from pollution.
• Specifically regulates pollutant discharges into
  navigable waters by implementing two concepts
• Setting water quality standards for surface
  water.
• Limiting effluent discharges into the water.

15
Industrial Water Pollution

• Factories and industrial complexes frequently
  dispose of waste in municipal sewage systems.
• May require special wastewater treatment.
• Often point sources.
• Mining
• Chemical run-off.
• Acid mine drainage.

16
In-Stream Uses

• In-stream water use makes use of water in its
  channels and basins.
• Non-Consumptive.
• Major in-stream uses are hydroelectric power,
  recreation, and navigation.
• Presently, hydroelectric power plants produce 13
  of a electricity generated in U.S.
• 10 grain goods carried by rivers

17
Kinds and Sources of Water Pollution

• Dissolved organic matter is a significant water
  pollution problem.
• Biochemical Oxygen Demand (BOD)
• Amount of oxygen required to decay a certain
  amount of organic matter.
• If too much organic matter is added, all
  available oxygen will be used up.
• Anaerobic bacteria begins to break-down waste.

18
(No Transcript)
19
Kinds and Sources of Water Pollution

• Nutrients can also be a pollution problem.
• Eutrophication - Excessive growth of algae and
  aquatic plants due to added nutrients.
• Particulate matter can also affect quality.
• Cover spawning sites.
• Acts as abrasive that injures organisms and
  carries toxic materials.

20
Dams

• Although hydroelectric dams control flooding and
  create electricity, they have drawbacks.
• High construction costs.
• Habitat destruction (above an below dam).
• Retard stream flow and silt deposition.
• Impounded water has elevated evaporation rate.
• Retard scouring effects of flooding.
• Reduced habitat regeneration.

21
Kinds and Sources of Water Pollution

• Point - Source of pollution readily located and
  identified.
• Municipal and industrial waste discharge pipes.
• Non-Point - Diffuse pollutants.
• Agricultural Runoff
• Much more difficult to identify and control.

22
Kinds and Sources of Water Pollution

• Municipal Water Pollution
• Wastes from homes consists primarily of organic
  matter from garbage, food production, and human
  waste.
• Fecal Coliform Bacteria - Generic term for
  bacteria found in warm-blooded animal,
  intestines.
• Numbers and types of bacteria present are
  directly related to amount of fecal matter
  entering system.

23
Agricultural Water Pollution

• Excessive fertilizer use may lead to
  eutrophication in many aquatic habitats.
• Runoff from animal feedlots carries nutrients,
  organic matter, and bacteria.
• Agricultural runoff from large, open expanses is
  major source of water pollution.
• Leave conservation buffer.
• Keep soil covered with crop.
• Control amount and timing of fertilizer
  application.

24
Municipal Water Pollution

• At one time, many detergents contained phosphates
  which contributed to eutrophication.
• Eliminated from most major detergents since 1994.
• Pharmaceuticals, hormones, detergent metabolites,
  insecticides, fire retardants, and coprostanol,
  among other chemicals, also found in municipal
  water discharge.

25
Municipal Water Pollution

• In a study of 139 streams throughout the Untied
  States, the USGS found one or more chemicals in
  80 of sampled streams.
• These chemicals largely escape regulation and are
  not removed by municipal wastewater treatment.

26
Thermal Pollution

• Thermal Pollution - Occurs when water is
  withdrawn, used for cooling purposes, and heated
  water is returned to original source.
• Steam from steam turbines must be condensed into
  water after leaving turbine for maximum
  efficiency.
• An increase in temperature, even a few degrees,
  may significantly alter some aquatic ecosystems.
• Decrease in dissolved oxygen.

27
Thermal Pollution

• Other Methods of Discharging Heated Water
• Large, Shallow Cooling Ponds
• Heat dissipated from pond.
• Cooling Towers
• Heated water sprayed into air and cooled by
  evaporation.
• Dry Tower
• Heated water pumped through tubes to release heat
  into the air.

28
Marine Oil Pollution

• Exxon Valdez (42 million liters of oil)
• U.S. National Oceanic and Atmospheric
  Administration Study
• 50 Biodegraded
• 20 Evaporated
• 14 Recovered
• 12 On Sea Bottom
• 3 On Shorelines
• 1 Still Adrift

29
Marine Oil Pollution

• Tanker accidents are spectacular, but more oil is
  released as a result of small, regular releases
  from other sources.
• 2/3 of all human-caused marine oil is from
• Street run-off.
• Improper disposal of lubricating oil.
• Intentional oil discharges during tanker loading
  and unloading.
• 1992 - New oil tankers must be double-hulled.
• Currently 15 of all tankers double-hulled.

30
Groundwater Pollution

• Major Sources
• Agricultural Products
• Pesticides
• Underground Storage Tanks
• Leakage
• Landfills
• Approximately 90 North American landfills have
  no liners to stop leakage.

31
Groundwater Pollution Sources

• Septic Tanks
• Over 20 million septic tanks in U.S..
• About one-third operating improperly.
• Surface Impoundments
• About 71 are unlined, while 73 have no
  restriction on the waste placed in the
  impoundment.

32
Sources of Groundwater Contamination
33
Salinization

• As plants extract water from the ground, salt
  content of the ground increases.
• Irrigation of arid farmland can make salinization
  more acute due to increased evaporation rates.
• Primarily a problem in areas under irrigation for
  several decades.

34
Groundwater Mining

• Removing water from an aquifer faster than it can
  be replenished.
• Extended periods of mining can lead to
• Land subsidence.
• Lowering of the water table.
• Salt-water intrusion of wells near coastal areas.

35
Saltwater Intrusion
36
Laws to prevent water pollution

• Federal water pollution control act 1948
  modified and made stronger 1972.
• Now called the Clean Water Act made stronger
  again in 1989.
• List 3 provisions of the clean water act.

37
Water Conservation

• What can you do to conserve fresh water?

38
(No Transcript)