Water

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 • http://www.msnbc.msn.com/id/21134540/vp/22431379#22431379