Chapter 15: Freshwater Resources Natural System, Human Impact
and Conservation www.aw-bc.com/Withgott Slide 2 A: Freshwater
Systems glaciers icecaps underground aquifers rivers & lakes
Slide 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
Slide 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 Slide 5 Diversity of Ecosystems in
Lakes and Ponds www.aw-bc.com/Withgott Slide 6 Groundwater
precipitation that percolates through the soil 20% of Earth's
freshwater unequal distribution climate change causing water
shortage Slide 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 Slide 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 Slide 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 Slide 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 Slide
11 Dam's Benefits ~prevents floods ~provide drinking water
~facilitate irrigation ~generates electricity ~emissions drop
~shipping geochange.er.usgs.gov/.../natural/codrought/ Slide 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 Slide 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 Slide 14 Ground Water
Depletion we are overusing it 160 km = 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 Slide 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 Slide 16
Solutions desalination plants freshwater from sea water expensive
requires energy creates large amounts of salty waste Slide 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 Slide 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 Slide 19 B: Water Pollution nutrient pollution:
eutrophication oligotrophiceutrophic www.aw-bc.com/Withgott Slide
20 Pollution pathogens and waterborne diseases: contamination by
human or animal waste cholera diphtheria Escherichia coli
salmonella Slide 21 Pollution toxic chemicals: synthetic chemicals
toxic metals pesticides petroleum based products acids from mining
drainage acid rain Slide 22 Pollution sediment mining clear-cutting
careless cultivation thermal pollution too warm can cause oxygen
depletion too cold can cause invasive species to thrive Slide 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 Slide 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 Slide 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 Slide 26 Sources of Groundwater
Pollution natural occur naturally in the environment can cause
toxicity in water arsenic in Bangladesh water wells Slide 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 Slide 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
Slide 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 Slide 30 Wastewater water that has been used sewage
showers washing machines dishwashers manufactures businesses
cleaning processes storm water runoff Slide 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 Slide 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 Slide 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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