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Water. The Water Cycle Global Water Storage 97% Oceans 2% Glaciers & Ice Caps 1% Groundwater Remaining: rivers, lakes, clouds, soil, living things.

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Presentation on theme: "Water. The Water Cycle Global Water Storage 97% Oceans 2% Glaciers & Ice Caps 1% Groundwater Remaining: rivers, lakes, clouds, soil, living things."— Presentation transcript:

1 Water

2 The Water Cycle

3 Global Water Storage 97% Oceans 2% Glaciers & Ice Caps 1% Groundwater Remaining: rivers, lakes, clouds, soil, living things

4 Watersheds: land areas surrounding a body of water

5 Groundwater

6 Groundwater Use and Overdraft Groundwater recharge is dependent on: – Rainfall – Rate of percolation (permeability) Groundwater overdraft is caused by: Withdrawing water faster than rainfall infiltrates the aquifer Overdraft can cause: – Water shortage – Subsidence – Saltwater intrusion

7 Residential Water Use Amounts and uses vary by region United States household use: – Lawn care & pools, toilets, bathing, cleaning, and cooking Water conservation: – Xeriscaping – Low-flow fixtures (toilet and shower) and appliances – Run only full loads of laundry and dishes – Change habits (turn off water, short showers, etc.)

8 Residential Water Treatment Public water supplies are tested and filtered (Regulated by: Safe Drinking Water Act) – Large objects are screened – Coagulation causes floc (sediment and bacteria) to settle to the bottom – Filters (sand & coal) remove remaining impurities – Chlorine kills bacteria, and water is aerated Private (household) wells are the homeowner’s responsibility – Well water can be tested by private companies

9 Industrial Water Use Industry uses greater quantities than households Surface water used more than groundwater Water is commonly used as coolant, or as solvent (or suspension) Water conservation recycles coolants and wastewater


11 Agricultural Water Use Agriculture uses greater quantities than industry – nearly 70% of total global water use Groundwater used more than surface water Water used for irrigation, waste disposal – Drip irrigation conserves water instead of overhead spray irrigation or flood irrigation – Grazing animals in open pasture instead of feedlots eliminates waste disposal lagoons and spraying

12 Spray and Furrow irrigation: Water lost to evaporation Drip irrigation: Water delivered directly to roots

13 Animal waste is stored in lagoons and then sprayed onto fields

14 Water Management Dams – Supply water for all uses (household, industrial, agriculture and recreation) – Damage river ecosystem Aqueducts – Move water from rural to city Flood Prevention – Jetties, levies, channelization, etc. – Often destroy wetlands and lead to long-term problems

15 Three Gorges Dam

16 Colorado River

17 Water Stress Many regions use more water than they receive by rainfall, causing water stress – Northern Africa, Middle East, Southwest United States, Central Asia Desalination is a solution – Distillation, freezing, or reverse osmosis

18 Water Pollution Water pollution has increased due to industrialization Point Sources – Industrial production factories – Sewage Treatment Plants (cities) Non-Point Sources – Runoff from roadways – Agricultural runoff (animal feedlots)


20 Pollutants: Pathogens Bacteria and other organisms that can cause illness – Caused by animal waste entering waterways (sewage) Examples – Cholera – Dysentry – Giardiasis – Cryptosporidium Harmful Effects – Diarrhea, vomiting, abdominal pain, other disease symptoms

21 Pollutants: Organic Matter Sewage, animal waste from feedlots, debris from deforestation, etc. Harmful Effects – Organic matter decomposes; process (respiration) depletes oxygen from the water


23 Pollutants: Organic Chemicals Pesticide and fertilizer runoff, oil spills, detergents, etc. Harmful Effects – Toxic to humans and wildlife – Bioaccumulation

24 Pollutants: Inorganic Chemicals Road salt runoff, acid mine drainage, industrial effluents, etc. Harmful Effects – Toxic to humans and wildlife – Corrode metals

25 Pollutants: Sediment Runoff of soil from land erosion – Increased by deforestation and development Harmful Effects – Reduced photosynthesis – Increased temperature – Depleted oxygen – Clog fish gills – Filtration required for drinking water

26 Pollutants: Thermal Pollution Water used as a coolant in industry (electrical power generation) is returned to river at higher temperature Examples: Indian Point Harmful Effects – Lowers D.O. levels – Increased risk of disease (bacteria and parasites)

27 Wastewater Treatment: Primary Treatment (separate solids from liquids) – Screens – Grit chamber – Sedimentation and coagulation Secondary Treatment (remove dissolved materials) – Aeration (filter or activated sludge) – Disinfection Advanced Treatment (optional) – Specifically designed for specified pollutants – Wetland application


29 Wastewater Treatment: Septic Tanks Sewer line from house to underground tank Tank designed to separate solid from liquid – Sedimentation: solid settles to bottom and is digested by bacteria – Liquid is pumped or drains from top to septic field where it is filtered by soil – Tank must be pumped out once filled with solids

30 Groundwater Pollution Pollutants enter groundwater by percolating through soil or from leaking underground tanks Groundwater is difficult to clean – Must wait for natural filtration processes – Bioremediation and other treatment may accelerate process

31 Ocean Pollution Oil Spills, litter, runoff, etc. – Chemicals cause bioaccumulation – Solids disrupt food web: animals feed on plastics 379 379

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