1. Water Resources & Pollution
AP Environmental Science
Ms. E. Rosa

2. What You Must Know
Importance of H20 & distribution of fresh H20 resources
Major types of freshwater systems
Categories of H20 use by humans & associated problems with utilization
Effective solutions addresses depletion
Main categories water pollutants & effect on quality
Main procedures involved drinking H20 & human wastewater treatment

3. Water’s Importance & Freshwater Distribution Resources
97.5% Earth’s water in Oceans
Only 2.5% is freshwater, most tied up in glaziers, icecaps & underground aquifers
Only 1% freshwater accessible.
Water unevenly distributed, from 470”/year in tropics to zero (Chile’s desert)
Humans not evenly distributed, arid lands more heavily populated where fresh is scarce

4. Water’s Importance & Freshwater Distribution Resources
Essential-maintains life/ecosystems
Regulates temperature, redistributes heat, cycles essential nutrients
Freshwater – renewable because hydrologic cycle only if managed sustainably
Industrial nations – concerns with quantity
Developing – quantity & quality
Global climate change will worsen disparity availability/human needs by altering precipitation patterns, melting glaciers, droughts, flooding

5. Major Types Freshwater
Surface water- freshwater found above ground includes streams, lakes, ponds, rivers, wetlands
Watershed – land area drained by river systems
¾ of all H20 in US comes surface used for generating electricity, industrial use, irrigation
Bodies of H20 classified productivity:

6. Bodies of H20 Classification
Oligotrophic- lakes/ponds with ↓nutrients & ↑O2
Eutrophic – water bodies ↑nutrients & ↓02
Wetlands: surface H20 systems soil is saturated with water generally featured as shallow standing water with noticeable vegetation
Marshes, swamps, bogs
Rich and productive

7. Wetlands
Vernal pools: seasonal wetlands have H20 specific time of year
Wetlands: valuable habitats wildlife, provide ecosystem services by slowing runoff, reduce flooding, recharge aquifers, filter pollutants
Extensive drainage in US has allow only half of all wetlands to remain

8. Groundwater As Aquifers withdrawn, recharge slowly
Water tables: ↑limit of groundwater held in aquifer
Average flow 1 m/day
When drop, become difficult & expensive to extract
Mexico, India, China, Asian & Middle Eastern, tables falling 3-10ft/year
Coastal: saltwater intrudes, land subsides creating sinkholes
Beneath earth’s surface held in pores of rocks/soil
Account ¼ of all H20 in US, supply almost ½ of all drinking H20
Aquifer: underground reservoir found in porous, sponge-like rock, sand, or gravel formations
Largest Ogalla Aquifer found under 8 US Great Plains states

9. Categories of H20: Humans Use & Associated Utilization Problems
Agriculture: accounts for 70% Earth’s annual freshwater use
Demand for human food has doubled land irrigation last 50 yrs.
Most irrigation inefficient, crops use 40% water applied
Over-irrigation:
Leads waterlogging, salinization of lands, ↓crop production
Worldwide % H20 withdrawal unsustainable

10. Categories of H20: Humans Use & Associated Utilization Problems
Industry-accounts 20% Earth’s fresh water use
Residential- 10%
Bottled H20 production- significant ground H20 extraction/depletion problem
Multinational corporations(Nestle, Pepsi, Coca) extract groundwater selling for profits, move on leaving community with degraded resource base
Bottled H20 ecological impact due to packaging/transportation (fossil fuels)
Not safer/healthier than tap

11. H20 Diversion Projects
Bring surface H20 fields, homes, cities thru dams, aqueducts, pipes, open-air canals
Colorado River – 13 major dams store H20 in reservoirs
Diverted H20 to irrigate crops in desert areas & sustain growth of Los Angeles, San Diego, Phoenix
California’s arid Imperial Valley – nation’s largest irrigation district(derived from Colorado River)
China: building world’s largest diversion to pipe from Yangtze River to Yellow River

12. H20 Diversion Projects
Channelization – widening, deeping, engineering technique to transport, flood control, & improve drainage of water
Causes extensive habitat destruction & fragmentation in many parts of world
Govt: protection against floods built dikes/levees for urban/residential areas (long raised mounds of earth) along riverbanks
Human development- worsens flooding due to paving, compacting soils speeds runoff, sends intense pulses of H20 into rivers during storm events

13. H20 Diversion Projects
Costs/benefits of damming rivers/streams being re-evaluated in US.
Largest US dam on Colorado River(Hoover & Glen Canyon Dam) each hold back reservoir that can be used to energy generation.
Habitat alteration is one main negative impact of dam’s construction
Some dams are being removed (due Costs)
Ecosystems restored,

14. Politics
Tensions may heighten future as depletion of fresh water contineues to lead shortages/resource scarcity
Human population grows, climate change continues to alter percipitation

15. Effective Solutions: Freshwater Depletion
Reducing demand focusing on conserving & increasing efficiency of use
Agriculture: Efficient irrigation methods
Drip irrigation, low-pressure spray, lining canal preventing leaks,
Choose crops match land & climate
Selective breeding & genetic modification
Recycling treated municipal H20 wastewater for irrigation

16. Effective Solutions: Freshwater Depletion
Residential:
Install low-flow faucets, showerheads, toilets, washing machines
Repairing leaks in pipes, water mains
Using gray water (wastewater from showers/sinks) to water lawns,
Xeriscaping – using plants that adapt to arid conditions

17. Effective Solutions : Freshwater Depletion
Increasing Supply
Desalination – removal of salt from seawater
Expensive, requires large fossil fuels, kills aquatic life at intakes, generates concentrated salty waste
Reverse Osmosis(microfiltration) and distillation 2 methods
Tampa, Florida largest desalinization plant in US
-Market-Based approaches
Privatization of water supplies