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Rivers and Streams - Physical Conditions

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Presentation on theme: "Rivers and Streams - Physical Conditions"— Presentation transcript:

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 Lake Structure Epilimnion

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

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


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