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Chapter 15: Freshwater Resources Natural System, Human Impact and Conservation www.aw-bc.com/Withgott.

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Presentation on theme: "Chapter 15: Freshwater Resources Natural System, Human Impact and Conservation www.aw-bc.com/Withgott."— Presentation transcript:

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

2 A: Freshwater Systems glaciers icecaps underground aquifers rivers & lakes

3 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 www.aw-bc.com/Withgott

4 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

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

6 Groundwater precipitation that percolates through the soil 20% of Earth's freshwater unequal distribution climate change causing water shortage

7 Aquifers porous spongelike 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 aeriation and saturation – confined aquifer: rain cannot get to it by filtration – unconfined aquifer: no upper layer that confines it

8 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

9 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

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

11 Dam's Benefits ~prevents floods ~provide drinking water ~facilitate irrigation ~generates electricity ~emissions drop ~shipping geochange.er.usgs.gov/.../natural/codrought/

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

13 Today's Problems Caused by Overuse major rivers' deltas are dry – Rio Grande, Colorado, Yangze between others causes tidal erosion – Yangze delta is eroding due to tides affecting industry and population – Aral sea shrinking and salinating fishing industry agricultural industry

14 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 salt intrusion at deltas – salt water can get to aquifers making water undrinkable – drop of water table causes sinkholes

15 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

16 Solutions desalination plants – freshwater from sea water – expensive – requires energy – creates large amounts of salty waste

17 Solutions reduce agricultural demand – choose crops that match the land and climate – improve efficiency of irrigation systems drip irrigation low pressure spray – target individual plants genetic modification

18 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

19 B: Water Pollution nutrient pollution: eutrophication oligotrophiceutrophic www.aw-bc.com/Withgott

20 Pollution pathogens and waterborne diseases: contamination by human or animal waste – cholera – diphtheria – Escherichia coli – salmonella

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

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

23 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

24 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

25 Groundwater Pollution extremely difficult to monitor non-point sources retains contaminants until they decompose decomposition can take decades – less O 2 – less microbes – less organic matter

26 Sources of Groundwater Pollution natural – occur naturally in the environment – can cause toxicity in water arsenic in Bangladesh water wells

27 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

28 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 http://oceanservice.noaa.gov/education/kits/pollution/media/supp_pol02d.html

29 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

30 Wastewater water that has been used – sewage – showers – washing machines – dishwashers – manufactures – businesses cleaning processes – storm water runoff

31 Treatments 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

32 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 bcn.boulder.co.us

33 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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