1 / 25

Biogeochemical Cycles - 2

Biogeochemical Cycles - 2. Class Lecture Goals Focus on the Water Cycle Unique aspects of water Understanding the behavior of water in streams (floods, power, salmon) Three case studies Chehalis River Flood Skagit Watershed: Loss of snow pack and glaciers Urban Watersheds. Reading.

spike
Télécharger la présentation

Biogeochemical Cycles - 2

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Biogeochemical Cycles - 2 Class Lecture Goals Focus on the Water Cycle Unique aspects of water Understanding the behavior of water in streams (floods, power, salmon) Three case studies Chehalis River Flood Skagit Watershed: Loss of snow pack and glaciers Urban Watersheds

  2. Reading Science 2004

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

  4. 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/Mass • • Index year (1950) • • Role of PDOs vs. climate change • • Uncertainty • • Shifts in timing of runoff • • Impacts on summer water

  5. 1913 2005 Glacier National Park Austrian Alps 150 to 26 http://www.msnbc.msn.com/id/6903014

  6. Water Cycle • Properties of water • Nature of stream flow (critical roles) • Three cases • Chehalis River flood • Skagit Watershed • Urban watershed http://ga.water.usgs.gov/edu/watercyclesummary.html

  7. 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.

  8. 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 (C as skeleton of life, water as medium of life) • Density of water (liquid vs. solid)

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

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

  11. Behavior of Water in a Watershed • Westside, little or NO snow, Calawah, Forks • Westside, lots of snow, Nooksack, Glacier

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

  13. 18 16 14 1. Chehalis River Flood

  14. 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

  15. 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

  16. Google Image of South Cascade River Watershed

  17. 2005 1928 2000 South Cascade Glacier from ~1850 (see blue overlay) to 2005 (see above photo).

  18. 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. Take home lesson: snow pack is less, melting earlier, stored water in glaciers is being depleted

  19. 3. Urban Watersheds - Thornton Creek

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

  21. Close-up a Sea-Street

  22. 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

  23. Major (Climate) Change Issues Premise: Clean, fresh water is a rare resource • Quantity of water (+ in form of snow, ice) • Seasonal and spatial distribution • Rain on snow • Loss of forests and vegetation • Increases in impervious surfaces • Demand for fresh water

  24. 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

More Related