Biogeochemical Cycles - 2 Class Lecture Goals 1.Focus on the Water Cycle 2.Unique aspects of water 3.Three case studies 1.Chehalis River Flood 2.Skagit Watershed: Loss of snow pack and glaciers 3.Urban Watersheds

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

Reading Science 2004

The concern about loss of snow pack is because snow water makes up __% of stream water in the west Answer Now! 10

Take-home messages 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 Premise: Glaciers, permanent snow fields and snow pack are the ‘water towers’ of the mountains

Water Cycle Image/Text/Data from the University of Illinois WW2010 Project

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

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.

Unique Properties of Water O H H O H H O H H O H H O H H O H H O H H Small molecule Three states: liquid, solid, gas Liquid from o C Takes lots of energy to change state or change temperature Transparent Solvent Solid vs. liquid Movement in plants

Understand the behavior of a watershed

Behavior of Water in a Watershed Use of a hydrograph (stream gauge) Time 012 DischargeRain Agriculture Forest Forest-Ag Urban

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

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

1. Chehalis River Flood

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

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

Google Image of South Cascade River Watershed

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

South Cascade Glacier Data Volume of South Cascade Glacier from ~1850 to Data for 1850 is an estimate. Glacier Volume (km 3 ) Year

3. Urban Watersheds - Thornton Creek

Alternatives Storage system Green roofs Example from Sea-Streets

Close-up a Sea-Street

In your view, which alternative seems the most viable 1.Using cisterns (tanks) to collect runoff 2.Requiring green roofs 3.Using the S.E.A.-Street model

Major (Climate) Change Issues 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 Premise: Clean, fresh water is a rare resource

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