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Biogeochemical Cycles - 2

Biogeochemical Cycles - 2. Class Lecture Goals Focus on the Water Cycle Unique aspects of water Three case studies Chehalis River Flood Skagit Watershed: Loss of snow pack and glaciers Urban Watersheds. Environmental Issues.

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Biogeochemical Cycles - 2

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  1. Biogeochemical Cycles - 2 Class Lecture Goals Focus on the Water Cycle Unique aspects of water Three case studies Chehalis River Flood Skagit Watershed: Loss of snow pack and glaciers Urban Watersheds

  2. Environmental Issues • Seattle Times - PI Sunday: Gravel pits as a a non-renewal resource • National Geographic Magazine - January (Recyling)

  3. Reading Science 2004

  4. 10 Answer Now! The concern about loss of snow pack is because snow water makes up __% of stream water in the west • 25 • 33 • 75 • 100

  5. Take-home messages Premise: Glaciers, permanent snow fields and snow pack are the ‘water towers’ of the mountains • • Decreased snow packs • • Biggest drops, lower elevations • • Biggest drops, PNW • • Snow is melting earlier in the spring • • Disagreement: Mote vs. Taylor • • Index year (1950) • • Role of PDOs vs. climate change • • Uncertainty • • Shifts in timing of runoff • • Impacts on summer water

  6. Water Cycle Image/Text/Data from the University of Illinois WW2010 Project http://ga.water.usgs.gov/edu/watercyclesummary.html

  7. Water Cycle Details • Properties of water • Nature of stream flow (critical roles) • Three cases • Chehalis River flood • Skagit Watershed • Urban watershed

  8. Quantities of Water • Changes in Ice • If all glaciers & icecaps melted today the seas would rise about 230 feet (70 meters). • During the last ice age, the sea level was about 400 feet (122 meters) lower than today. • During the last warm spell, 125,000 years ago, the seas were about 18 feet (5.5 meters) higher than today.

  9. O O O O O O O H H H H H H H H H H H H H H - - - - - - - - - - - - + + + + + + + + + + + + Unique Properties of Water • • Small molecule • Three states: liquid, solid, gas • Liquid from 0 - 100oC • Takes lots of energy to change state or change temperature • Transparent • Solvent • Solid vs. liquid • Movement in plants

  10. Understand the behavior of a watershed http://wa.water.usgs.gov/realtime/rt_latest_map.html

  11. Agriculture Urban Forest-Ag Forest Behavior of Water in a Watershed • Use of a hydrograph (stream gauge) Discharge Rain 0 12 Time

  12. Behavior of Water in a Watershed • Westside, little or no snow • Westside, lots of snow

  13. Behavior of Water in a Watershed • Eastside, snow, NE WA • Urban - suburban stream

  14. 18 16 14 1. Chehalis River Flood

  15. Effects of trees vs. no trees • Assume 100” • Amount & type of precipitation (ppt) - no difference. • Trees intercept ppt (5 - 15%) • Forest soil is drier: Trees transpire (20%) • Snow stays colder under forest • Snow accumulates more slowly under forest • Roots provide strength • Roads are bad

  16. 2. Skagit Watershed • Third largest on the west coast of US • 3100 mile2 (about 1/6th in Canada) • Major agriculture • Major salmon • National Park • Seattle City Light

  17. Google Image of South Cascade River Watershed

  18. 1928 2000 South Cascade Glacier from ~1850 (see blue overlay) to 2005 (see above photo).

  19. 1890 1928 2001 2005 Glacier Volume (km3) Year South Cascade Glacier Data Volume of South Cascade Glacier from ~1850 to 2005. Data for 1850 is an estimate.

  20. 3. Urban Watersheds - Thornton Creek

  21. Alternatives • Storage system • Green roofs • Example from Sea-Streets

  22. Close-up a Sea-Street

  23. 9 Answer Now! In your view, which alternative seems the most viable • Using cisterns (tanks) to collect runoff • Requiring green roofs • Using the S.E.A.-Street model

  24. Major (Climate) Change Issues Premise: Clean, fresh water is a rare resource • Quantity of water • Seasonal and spatial distribution • Form of water/rain on snow • Cloud and fog formation and spatial distribution • Uses of water • Loss of forests and vegetation • Increases in impervious surfaces

  25. Summary: Water Cycle • Water cycle: Quantity, Quality, Form, & Timing • Properties of water • Watershed • Climate, geographic location and water • Three cases • Chehalis Flood • Skagit Watershed • Urban Watersheds

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