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Chapter 15: Freshwater Resources

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Presentation on theme: "Chapter 15: Freshwater Resources"— Presentation transcript:

1 Chapter 15: Freshwater Resources
Natural System, Human Impact and Conservation

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

3 Wetlands diverse ecological systems slow runoff reduce flooding
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

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

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 blocks flow of water
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

11 Dam's Benefits ~prevents floods ~provide drinking water
~facilitate irrigation ~generates electricity ~emissions drop ~shipping

12 Dikes and Levees flood prevention can fail
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

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

17 • genetic modification
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 oligotrophic

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 thermal pollution 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 O2 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)
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

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

32 Treatments sewer systems in populated areas primary treatment 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

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

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