This document summarizes key topics related to freshwater resources and water pollution. It discusses the properties and importance of water, noting that only 1% of Earth's water is available freshwater and many regions will face shortages by 2025. Issues covered include too much/too little water, water conflicts, the hydrologic cycle, surface and groundwater, causes of water pollution from various sources, and approaches to water conservation and pollution control. The document emphasizes the need for sustainable water management given growing demands on limited supplies.

1. Freshwater Resources and
Water Pollution

2. Properties of Water
 Molecules of water: H2O
– 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. 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. •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.
Evaporation and transpiration
Evaporation
Infiltration
Unconfined aquifer
Confined aquifer
Well requiring a pump
Flowing
artesian well
Runoff
Precipitation
Confined
Recharge Area
Less permeable material
such as clay
Confining permeable rock layer
Unconfined Aquifer Recharge Area
Water table

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
40-60%

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
Nonpoint source
Enters over a large area
Runoff (agriculture or,
urban lawns) or
atmospheric deposition
Point source: specific spot

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