1. Freshwater Resources and Water Pollution

2. Properties of Water Molecules of water: H2O Polar molecule
2 Hydrogen atoms
1 Oxygen atom
Polar molecule
One end slightly positive
One end slightly negative

3. Properties of Water
Hydrogen bonds that result from water’s polarity responsible for many of water’s properties
High heat capacity
(Moderates climate)
Universal solvent

4. The Importance of Water
All living things need water
Composes majority of the body of organisms
Habitat for many organisms
Helps regulate climate
Shapes earth’s surface
Dilutes & degrades wastes

5. Water on Earth
About 97% Earth’s water is salty–less than 1% of the planet’s water is available fresh H2O
Fresh water is distributed unevenly
2025: 1/3 human population will live in areas lacking fresh water

6. Water, water, everywhere? (NOT)
Comparison of population sizes and shares of the world’s freshwater among the continents. (Only 7 countries account for 60% of global water availability)

7. Water Wars
Many countries in the Middle East, which has one of the world’s highest population growth rates, face water shortages.

8. Water wars cont…
Most water in this dry region comes from the Nile, Jordan or Tigris rivers.
Countries are in disagreement as to who has water rights.
Currently, there are no cooperative agreements for use of 158 of the world’s 263 water basins that are shared by two or more countries.

9. The Hydrologic Cycle

10. Surface Water Streams, rivers, lakes, ponds, reservoirs, wetlands
Runoff replenishes surface water
Watershed
Area of land drained by a single river
What watershed do we live in?

11. Groundwater
Supply of fresh water found under Earth’s surface--recharged when water at surface infiltrates into the ground
Stored in under
ground aquifers
Discharged into
rivers, springs,
etc…

12. Zone of Aeration - Upper soil layers that hold both air and water.
Infiltration - Process of water percolating through the soil and into cracks and permeable rocks.
Zone of Aeration - Upper soil layers that hold both air and water.
Zone of Saturation Lower soil layers where all spaces are filled with water.
Water Table - Top of zone of saturation

13. Evaporation and transpiration
Precipitation
Unconfined Aquifer Recharge Area
Flowing
artesian well
Evaporation and transpiration
Confined
Recharge Area
Evaporation
Infiltration
Runoff
Well requiring a pump
Unconfined aquifer
Water table
Less permeable material
such as clay
Confined aquifer
Confining permeable rock layer
Recharge Zone - Area where water infiltrates into an aquifer. -Recharge rate is often very slow. -Presently, groundwater is being removed faster than it can be replenished.

14. Aquifers - Porous layers of sand, gravel, or rock lying below the water table.

15. Water Resource Problems
Too much water
Too little water
Poor-quality water

16. Changes in Surface Runoff
Prior to 1970 about 10% of stormwater became runoff
Now 55% of stormwater is transported as runoff as development exceeds 75% of the permeable soil area

17. Stormwater Runoff (greatest contributor to nonpoint source pollution) contains:
Nutrients*
Metals*
Suspended solids*
Pesticides
Hydrocarbons
Microorganisms
*Present in nearly 100% of stormwater samples

18. Too Much Water
Heavy rainfall, rapid snowmelt, removal of vegetation, and destruction of wetlands cause flooding.
Floodplains, which usually include highly productive wetlands, help provide natural flood and erosion control, maintain high water quality, and recharge groundwater.
To minimize floods, rivers have been narrowed with levees and walls, and dammed to store water.

19. Human activities have contributed to flood deaths and damages

20. Too Little Water
Arid & semiarid lands (growing in extent -- desertification)
Irrigation required to produce food
Greatest use of water (71%)

21. Aquifer Depletion Removing groundwater faster than it is replenished
Lowers water table
Land subsidence
Saltwater intrusion
Salt water seeps into fresh water
Occurring in
South Florida

22. Overdrawing Surface Waters
Damaging to ecosystems
Wetlands dry up (Everglades)
Estuaries become too salty (FL Bay)
Worldwide, the demand for water is growing as the human population and indvidual consumption continue to grow exponentially
Water wars
Arial Sea

23. Water Management Goal: sustainable supply of high quality water
How do we supply water?
Building dams (ex: Columbia River)
Diversion (ex: Colorado River)
Desalination (ex: FL Keys) - very expensive to build & operate plants

24. Water Conservation: Agriculture
Single largest user of water worldwide
Much lost to evaporation or seepage
Solution: drip irrigation
Perforated pipes distribute water
Goes straight to plants
Reduces water use %

25. Water Conservation: Municipal
Solutions:
Use gray water
Education: modify habits
Water-saving fixtures
& Appliances
Repair leaks
Cisterns & rain barrels
Water gardens

26. Water Pollution
Physical or chemical change in water that adversely affects the health of humans or other organisms
Global problem

27. Eutrophication Build up of nutrients in a body of water
Naturally occurs slowly
Humans cause imbalances
by creating pulses of
nutrients due to over-
fertilizing crops & lawns
and raising animals in
confined areas
Nutrients include nitrogen and phosphorus-containing
compounds that are essential to life in small quantities
but harmful in excess.

28. Sources of Water Pollution
Point source: specific spot
Nonpoint source
Enters over a large area
Runoff (agriculture or, urban lawns) or atmospheric deposition

29. Groundwater Pollution Sources

30. Controlling Water Pollution
1. Source Reduction (Pollution Prevention)
Cheapest and most effective way to reduce pollution is to avoid producing it or releasing it into the environment.
Design products that do not pollute
Soil Conservation
2.Ban release of pollutants
3.Reward purchasing environmentally preferable products (e.g. rebates)

31. The End