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Freshwater and Society

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Freshwater and Society Module 1, part B * Graphic from C. Svendsen Use this to review with the students the take home concepts of surface water, soil ... – PowerPoint PPT presentation

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Title: Freshwater and Society


1
Freshwater and Society
  • Module 1, part B

2
Watersheds
3
Hydrological cycle of a watershed
4
Watershed definition
  • Watershed
  • An area of land that drains water, sediment and
    dissolved materials to a common receiving body or
    outlet
  • The term is not restricted to surface water
    runoff and includes interactions with subsurface
    water
  • Watersheds vary from the largest river basins to
    just acres or less in size

5
Organization of watersheds
  • A divide represents the boundary of a watershed
  • Larger watersheds can often be divided into
    smaller units called subbasins, drainage areas,
    or water resource inventory areas

6
Watersheds
7
Watershed components
  • Latitude, albedo climate
  • Geology
  • Topography
  • Land Use
  • Vegetation and impervious surfaces

8
Watershed components Latitude
  • Energy input into a watershed depends on solar
    height and length of daylight hours
  • Determined by the latitude and season
  • May 21, Seattle, WA solar altitude at noon is
    62.500
  • January 21, Seattle solar altitude at noon is
    22.500

9
Watershed components Albedo
Albedo is the reflectance of a surface. The higher the reflectance the less energy input into a watershed. Albedo is the reflectance of a surface. The higher the reflectance the less energy input into a watershed.
Surface Cover Albedo ()
Water 5-10
Bare soil (light colored, dry) 20-35
Marsh and Bogs 15-20
Forest (dense spruce) 5-10
Forest (hardwoods in leaf) 15-20
Snow (fresh) 80-95
Snow (old) 40-70
10
Watershed components Climate
http//www.eia.doe.gov/emeu/recs/origin/climzone.g
if
  • Temperature regime
  • Relative humidity
  • Precipitation patterns

http//www.epa.gov/ceisweb1/ceishome/atlas/nationa
latlas/climatezones.htm
11
Watershed components Climate
  • Precipitation
  • Temperature
  • Relative humidity (RH)
  • Wind

12
Watersheds Average annual precipitation

13
Watersheds Potential evapotranspiration

14
Watersheds Water surplus or deficit

15
Watershed components Geology
  • Bedrock
  • Type and distribution of soils

16
Geology Soil permeability
  • The ease with which water penetrate or pass
    through a bulk mass of soil or a layer of soil

17
Geology soil pore space and water content
  • Total porosity of a soil determines maximum water
    content at saturation soils within zone of
    aeration are seldom saturated.
  • Textural (primary) porosity voids between
    aggregates.
  • Structural (secondary) porosity voids
  • within aggregates fracture or poor
  • zones

http//wrgis.wr.usgs.gov/open-file/of99-168/Pp-lim
estone.jpg
18
Geology Groundwater vs. soil moisture
  • Groundwater
  • Subsurface water in the zone of saturation that
    is free to move under the influence of gravity,
    often horizontally to stream channels
  • Soil Moisture
  • Subsurface water in the unsaturated zone held in
    place by capillary forces or osmotic pressure

19
Geology moisture content of various soils

20
Geology Infiltration
  • Infiltration is the flow of water downward
    through the upper layers of soil

21
Geology infiltration capacity during a storm

22
Geology soil moisture profile after a rain event

23
Geology seasonal infiltration trends

24
Geology seasonal variation in watershed runoff

25
Geology Saturation and runoff generation
26
Watershed components Topography
  • Topography
  • Slope
  • Aspect

27
Watershed components Topographic interactions
28
Watershed components Land use and vegetation
  • Vegetation
  • Slows runoff
  • Reduces soil compaction
  • Prevents soil erosion
  • Reduces pace of raindrop splash
  • Reduce soil material moving downslope
  • Influences timing of snowmelt runoff
  • Influences water yield

29
Land use Stormwater discharge vs. land use
30
Land uses Effects upon hydrology/water quality
  • Natural Events
  • Fires
  • Wind storms
  • Disease outbreaks
  • Floods
  • Volcanoes
  • Climate change
  • Land Uses
  • Flood control
  • Timber production
  • Urban development
  • Hydroelectric
  • Agriculture
  • Mining

31
Watershed components land Use

32
Organization of a watershed
33
Watershed Water budgets
  • Water budget
  • Evaluation of sources of supply vs. discharges
    with respect to a drainage basin

34
Watershed Water budgets
  • Annual water budget for Lawrence Lake, Michigan,
    and Mirror Lake, New Hampshire

35
Watershed Water budgets
  • Water budgets provide a graphic depiction of the
    distribution of moisture throughout the year in
    any given area
  • An idealized budget, however, is rarely achieved
  • Examples from Los Angles, CA and Pullman, WA,
    illustrate the range of potential deviation from
    the ideal water budget

36
Watershed water budget Pacific Northwest
37
Watershed Aquatic ecoregions
  • North America has been divided into eight major
    aquatic ecoregions
  • Arctic rivers and lakes
  • Large temperate lakes
  • Temperate headwaters and lakes
  • Large temperate rivers
  • Endorheic rivers, lakes, and springs
  • Xeric-region rivers, lakes, and springs
  • Temperate coastal rivers and lakes
  • Subtropical coastal rivers and lakes

38
Aquatic Ecoregions of North America
39
Watershed components
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