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Chapter 15: Freshwater Resources

Chapter 15: Freshwater Resources. Natural Systems, Human Impacts and Conservation. www.aw-bc.com/Withgott. A: Freshwater Systems. Glaciers – surface water Icecaps – surface water underground aquifers - groundwater rivers & lakes – surface water. Rivers and Lakes – surface water.

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Chapter 15: Freshwater Resources

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  1. Chapter 15: Freshwater Resources Natural Systems, Human Impacts and Conservation www.aw-bc.com/Withgott

  2. A: Freshwater Systems • Glaciers – surface water • Icecaps – surface water • underground aquifers - groundwater • rivers & lakes – surface water

  3. Rivers and Lakes – surface water • Flood plain – areas near a river that are occasionally flooded • Riparian areas – area alongside a river; has characteristic vegetation, herbivores, etc. Can act as both recharge and discharge areas

  4. www.aw-bc.com/Withgott Wetlands • diverse ecological systems • slow runoff • reduce flooding • recharge aquifers • filter pollutants • combinations of freshwater and dry land • marshes: plants are allowed to grow above water level • swamps: same as marshes but present in forest areas • bogs: ponds roughly covered by vegetation

  5. Lakes and Ponds • open standing water • ecosystems vary according to depth • littoral zone~ shores • benthic zone~ bottom of lake • limnetic zone~ away from shores, top of lake • profundal zone~ similar to benthic, no sunlight

  6. Diversity of Ecosystems in Lakes and Ponds www.aw-bc.com/Withgott

  7. Groundwater • precipitation that percolates through the soil • Capillary water is “held on to” by E- charges • 20% of Earth's freshwater • unequal distribution • climate change causing water shortage

  8. Aquifers • porous sponge-like formation of rock, sand and gravel formed by • zone of aeration: not completely saturated • zone of saturation: saturated with water • water table: limit between zones of aeration and saturation • confined aquifer: rain cannot get to it by filtration • unconfined aquifer: no upper layer that confines it

  9. A diagram of an aquifer

  10. HOMEWORK • REVIEW HYDROLOGIC CYCLE pages 196 – 198 • Read assignment on syllabus • KNOW THESE TERMS • Floodplain • Wetlands • Groundwater • Aquifer, confined & unconfined • Capillary water • Watershed

  11. Average Water Usage • world wide→ 170,616 gal/yr/person • U.S.A.→ 509,000 gal/yr/person • poor countries→ 16,425 gal/yr/person • source: U.N. Environmental Program 2002

  12. Water Usage • altering environmental systems • dams • canals • diversions • consumptive use~ water is consumed • irrigation • nonconsumptive use~ water is returned to the system after use • hydroelectric

  13. Dam's Drawbacks • risk of failure • Three Gorges dam cracks and sedimenting • blocks flow of water • fisheries fail (salmon in Columbia River) • sedimentation (Anwar Dam in Egypt) • population displacement (Three Gorges Dam) • affects ecosystems • Hoover Dam was recently opened to restore the ecosystem www.northlasvegaschamber.com

  14. Dam's Benefits ~prevents floods ~provides drinking water ~facilitates irrigation ~generates electricity ~emissions drop ~shipping geochange.er.usgs.gov/.../natural/codrought/

  15. Dikes and Levees • flood prevention • along banks of rivers • can fail • flooding is a natural process • heavy rain • snow melt • spreads nutrient-rich sediments

  16. Today's Problems Caused by Overuse • major rivers' deltas are dry • Rio Grande, Colorado, Yangtze • causes tidal erosion • Yangtze delta is eroding due to tides • affecting industry and population • Aral Sea shrinking • fishing industry • agricultural industry

  17. Ground Water Depletion • we are overusing it • 160 km³ = 100 cubic miles of water used that is not replaced by rain • water table is dropping • causing saltwater intrusion at deltas • saltwater can flow into aquifers making water undrinkable • drop of water table causes sinkholes - subsidence

  18. Solutions to Water Depletion • reducing demand • conservation • xeriscaping • water lawn at night • efficiency • showers • washing machine • dishwasher • low-flow faucets • toilets www.aw-bc.com/Withgott

  19. Solutions • desalination plants • freshwater from sea water • expensive • requires energy • creates large amounts of salty waste

  20. Solutions • reduce agricultural demand • choose crops that match the land and climate • improve efficiency of irrigation systems • Line irrigation canals to minimize leaks • Reduce evaporation of water being used • drip irrigation - targets individual plants • low pressure spray •genetic modification

  21. Economic Approaches for Water Conservation • end subsidies to inefficient practices • let water become a commodity • privatization of water supplies • decentralization of control over water • education

  22. Homework due Homework: • Answer questions on page 440 – • Testing comprehension # 6 - 10 • seeking solutions # 1, 4, 5, 6 • interpreting graphs and data # 3

  23. Homework due Feb. 13 (or 14) • Go to this website: http://ngm.nationalgeographic.com/2010/04/table-of-contents • Answer the questions given to you on a separate sheet of paper - to be handed in!

  24. B: Water Pollution • nutrient pollution: eutrophication oligotrophic eutrophic www.aw-bc.com/Withgott

  25. Pollution • pathogens and waterborne diseases: contamination by human or animal waste • cholera • diphtheria • Escherichia coli • salmonella

  26. Pollution • toxic chemicals: synthetic chemicals • toxic metals • pesticides • petroleum based products • acids from mining drainage • acid rain

  27. Pollution • sediment • mining • clear-cutting • careless cultivation • thermal pollution • too warm can cause oxygen depletion • too cold can cause invasive species to thrive

  28. Sources of Water Pollution • point sources • oil spills • industrial waste • sewage plants • non-point sources • animal feedlots • fertilizers from farms, homes and clubs • pesticides from farms, homes and clubs • herbicides from farms, homes and clubs • salt and sand on winter roads • chemicals from urban runoffs • PPCPs

  29. Water Quality Indicators • biological • presence of fecal coliform bacteria • disease causing pathogens • physical • turbidity→ presence of sediments • color→ indicates presence of certain chemicals • temperature→ can affect biological processes

  30. Groundwater Pollution • extremely difficult to monitor • non-point sources • retains contaminants until they decompose • decomposition can take decades • less O2 • less microbes • less organic matter

  31. Sources of Groundwater Pollution • natural • occur naturally in the environment • can cause toxicity in water • arsenic in Bangladesh water wells

  32. Sources of Groundwater Pollution • human activity • pathogens and pollutants • underground liquid hazardous waste • septic tanks • tanks of industrial chemicals • oil/gas tanks • nitrates from agriculture fertilizers • cancer • miscarriages • blue-baby syndrome • industrial and military waste

  33. http://oceanservice.noaa.gov/education/kits/pollution/media/supp_pol02d.html Legislation • Federal Water Pollution Control Act (1972) • later Clean Water Act (1977) • illegal to discharge pollution from a point source unless permit was given • standards for wastewater • standards for contaminant levels • funds for sewage treatment plants

  34. Prevention vs. Mitigation • prevention is cheaper • consumer choice • phosphorus-free detergents • environmentally friendly products • local groups of volunteers collect pollutant data • state and federal regulation

  35. Wastewater • water that has been used • sewage • showers • washing machines • dishwashers • manufactures • businesses cleaning processes • storm water runoff

  36. Review the nitrogen cycle!

  37. Treatments – see diagram p. 438 • Municipal wastewater • septic systems in rural areas • underground • microbes break organic matter • needs to be taken to landfill periodically • emits gases lawcoswm.org/septictank.htm

  38. bcn.boulder.co.us Treatments • sewer systems in populated areas • primary treatment • physical removal of up to 60% suspended solids • secondary treatment • water is aerated to promote bacteria activity • 90% of solids are removed • chlorine and UV rays applied to kill all bacteria • water is piped back to rivers/lakes/ocean • reclaimed water used as "grey water" • leftover sludge is disposed, incinerated or used as fertilizer

  39. Treatments • artificial wetlands • primary treatment is done in a conventional manner • microbes, aquatic plants, fishes, algae • filter and clean the water • biosolids used for energy • problems may happen • prairie dogs The End www.aw-bc.com/Withgott

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