Lecture - Chapter 14 - Water as a Limited Resource.ppt
- 2. Chapter 14 Water: A Limited Resource
- 3. Importance of Water o Cooking o Washing o Use large amounts for: • Agriculture • Manufacturing • Mining • Energy production • Waste disposal o Use of freshwater is increasing
- 4. Properties of Water o Composed of 2 Hydrogen and 1 oxygen o Exists as solid, liquid or gas o High heat capacity o Polar • One end has (+) charge, one end has (-) charge o Forms Hydrogen bond between 2 water molecules • H-bonds define water’s physical properties
- 5. Properties of Water o Water is never completely pure in nature o Content of seawater (left) o Many substances water dissolves cause water pollution
- 7. Distribution of Water o Only 2.5% of water on earth is freshwater o 2% is in the form of ice! o Only ~0.5% of water on earth is available freshwater
- 8. Freshwater Terminology o Surface water • Precipitation that remains on the surface and does not seep into soil o Runoff • Movement of surface water to lakes, rivers, etc. o Watershed (drainage basin) • Land area that delivers water into a stream or river system o Groundwater • Freshwater under the earth’s surface stored in aquifers o Aquifer • Underground caverns and porous layers of sand, gravel and rock in which groundwater is stored
- 10. Water Use and Resource Problems o Fall into Three Categories • Too much water • Too little water • Poor quality/contamination (discussed in Chapter 22)
- 11. Too Much Water o Flooding • Both natural and human-induced o Modern floods are highly destructive because humans: • Remove water-absorbing plant cover from soil • Construct buildings on floodplains o Floodplain • Area bordering a river channel that has the potential to flood
- 12. Urban vs. Pre-Urban Floodplains
- 13. Floodplain o Government restrictions on building • Levees can fail o Rather than rebuild levees adjacent to rivers, experts suggest allowing some flooding of floodplains during floods • (next slide)
- 14. Left: Traditional levees adjacent to river Right: Suggested levee style, set back from river
- 15. Case-In-Point Floods of 1993
- 16. Too Little Water o Typically found in arid land o Problems • Drought • Overdrawing water for irrigation purposes • Aquifer depletion • Subsidence • Sinkholes
- 17. Too Little Water o Problems (continued) • Saltwater Intrusion
- 18. Water Problems In US and Canada o US has a plentiful supply of freshwater o Many areas have a severe shortages • Geographical variations • Seasonal variations
- 19. Water Problems in US and Canada o Water shortages in West and Southwest • Water is diverted and transported via aqueducts
- 20. Water Problems in US and Canada- Surface Water o Mono Lake (Eastern CA) • Rivers and streams that once fed this lake are diverted to Los Angeles (275mi away) • Becoming highly saline • Court ordered water diversion reduction o Colorado River Basin • Provides water for 27-million people • Numerous dams for Hydropower • Colorado River no longer reaches ocean
- 21. Colorado River bed in Mexico
- 22. Water Problems in US and Canada- Groundwater o Aquifer Depletion Ogallala Aquifer
- 23. Global Water Problems o Amount of freshwater on planet CAN meet human needs • BUT, it is unevenly distributed and some places lack stable runoff o Problems: • Climate Change • Drinking Water • Population Growth • Sharing Water Resources Among Countries
- 24. Global Water Problems o Water and Climate Change • Climate change affects the type and distribution of precipitation • Potential issues: • Reduced snowfall will impact water resources downstream • Sea level rise will cause saltwater intrusion into drinking water supplies
- 25. Global Water Problems o Drinking Water Problems • Many developing countries have insufficient water to meet drinking and household needs o Population Growth • Increase in population means an increase in freshwater requirements • Limits drinking water available • Limits water available for agriculture (food)
- 26. Global Water Problems o Sharing Water Resources Among Countries • Rhine River Basin (right) • Countries upstream discharged pollutants into river • Countries downstream had to pay to clean the water before they could drink it • Aral Sea (next slide) • Water diversion for irrigation has caused sea to become too saline
- 28. Global Water Problems o Potentially Volatile International Water Situations • Jordan River • Nile River
- 29. Water Management o Main Goal: Provide sustainable supply of high-quality water • Requires humans to use resource carefully o Dams and Reservoirs o Water Diversion Projects o Desalinization
- 30. Dams and Reservoirs o Benefits: • Ensure year-round supply of water with regulated flow • Generate electricity • Provide recreational activities o Disadvantages • Alter the ecosystem • Reduce sediment load
- 31. Dams and Reservoirs o Glen Canyon Dam • Regulated flow has changed ecosystem o To rectify situation • Canyon has been flooded several times • Small floods compared to natural floods • Still helps rebuild habitat
- 32. Dams and Reservoirs o Salmon Population in Columbia R. very low due to dams that impede migration o Fish ladders help, but are not effective enough
- 33. Water Diversion Projects o Requires diverting water to areas that are deficient by pumping through a system of aqueducts o Much of CA’s receives its water supply from diverted water from Northern CA o Controversial and expensive
- 34. Desalinization o Removal of salt from ocean or brackish water o Two methods: • Distillation- salt water is evaporated, and water vapor is condensed into freshwater (salt left behind) • Reverse Osmosis- involves forcing salt water through a membrane permeable to water, but not salt o Very expensive
- 35. Water Conservation o Reducing Agricultural Water Waste • Agriculture is very inefficient with water • Microirrigation- irrigation that conserves waster by piping to crops through sealed systems • Also called drip or trickle irrigation
- 36. Water Conservation o Reducing Industrial Water Waste • Stricter laws provide incentive to conserve water • Recycling water within the plant • Water scarcity (in addition to stricter pollution control requirements) will encourage further industrial recycling • Potential to conserve water is huge!
- 37. Water Conservation o Reducing Municipal Water Waste o Gray Water • Can be used to flush toilets, wash car or water lawn o Water saving household fixtures o Government incentives
- 38. Population Increases (1990-2000) Population increases from 1990-2000 in % Annual electricity consumption growth rates from 1988 to 1998 (%) Source: California Energy Commission, Electricity Analysis Office
- 39. Population Projections Population Projections (2000-2030) Greatest increases expected in the driest states. Source: U.S. Census Bureau NEEDS: FRESH WATER!
- 40. Snow Survey and Water Supply Forecasting Program o 12 western states including Alaska o 60 FTE (36 Field, 24 NWCC) o 25.5M acres of irrigated agriculture o $51.1B in annual market value (Ag. Census, 2002)
- 41. NRCS SNOTEL Network o SNOTEL network • 12 western states • 730+ sites • 16 million observations (2005) • 16.1 million downloads o 920 manual snow courses
- 43. SNOTEL Site Augmented Data Array o Snow water content o Precipitation o Temperature o Snow depth o Relative humidity o Wind speed/direction o Solar radiation o Soil moisture / temperature
- 44. NWCC Webpage
- 45. Mt. Rose SNOTEL Data
- 46. Water Supply Forecasts o Water Year 2006 • 740 locations forecast Jan-Jun with NWS • Over 11,534 forecasts issued by states to users • Over 1.9M visits to WSF pages
- 47. New Products - WSF Rapid changes in snowpack affect water supply forecasts
- 48. New Products – Climate Maps o Maps of snowpack, precipitation, temperature Oregon State University http://www.ocs.orst.edu/prism/