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 west25 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
Glacier National Park Austrian Alps
150 to 26
2005

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

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. Unique Properties of Water
• Small molecule
Three states: liquid, solid, gas
Liquid from oC
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) O H - +

9. Understand the behavior of a watershed

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

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. 1. Chehalis River Flood 14 16 18

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

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