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Rivers and Streams - Physical Conditions

Rivers and Streams - Physical Conditions. Light How much light shines on the surface. How far light penetrates the water column. Water Movements Erosion from land. Suspended bottom sediments. Temperature Closely tracks air temperature. Aquatic Temperatures.

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Rivers and Streams - Physical Conditions

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  1. Rivers and Streams - Physical Conditions • Light • How much light shines on the surface. • How far light penetrates the water column. • Water Movements • Erosion from land. • Suspended bottom sediments. • Temperature • Closely tracks air temperature.

  2. Aquatic Temperatures • Riparian vegetation (stream side forest) influences stream temperature by shading.

  3. Rivers and Streams • Chemical Conditions • Salinity • Reflects history of leaching in the basin. • Oxygen • Inversely correlated with temperature. • Usually not limiting in river systems. • Human Influence • Long, intense history of human use. • Transportation, Irrigation, Waste Disposal.

  4. Dimensions of Stream Structure

  5. Rivers and Streams • Rivers and streams are vertically divided into water surface, water column, and bottom (benthic). • Hyporheic Zone: Transition between surface water and groundwater. • Phreatic Zone: Groundwater • Stream Order • First Order - Headwater • Second Order - Joining of two first order. • Third Order - Joining of two second order.

  6. Major Rivers

  7. Lakes • Most of the world’s freshwater resides in a few large lakes. • Great Lakes of North America contain 20% of freshwater in the world.

  8. Lakes - Structure • Structure • Littoral zone: Shallows • Limnetic zone: Open lake • Epilimnion: Warm surface layers. • Metalimnion: Temperature changes with depth. • Hypolimnion: Cold dark waters.

  9. Epilimnion Lake Structure

  10. Lakes - Physical Conditions • Light • Lake color depends on light absorption and biological activity. • Temperature • Lakes become thermally stratified as they warm. • Water Movement • Wind-driven mixing of the water column is ecologically important.

  11. Lakes - Chemical Conditions • Oxygen • Oligotrophic: Low biological production, although often well oxygenated.

  12. Lakes - Chemical Conditions • Oxygen • Eutrophic: High biological production, but may be depleted of oxygen.

  13. Lakes - Human Influences • Human populations have had profound, usually negative effect. • Municipal and agricultural run-off. • Exotic species - Zebra Mussels http://nationalatlas.gov/zmussels1.html

  14. Wetlands • Soil is covered with water for some or all of the year • Functions/ecosystem services • Fish and wildlife habitat • Water filtration • Flood storage

  15. http://www.epa.gov/owow/wetlands/

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