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Streams and Stream Flow

Streams and Stream Flow. What is a Drainage Basin?. Drainage basin A drainage system which consists of a surface stream or a body of surface water together with all tributary surface streams and bodies of water. Watershed The area whose runoff flows to a particular stream

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Streams and Stream Flow

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  1. Streams and Stream Flow

  2. What is a Drainage Basin? • Drainage basin • A drainage system which consists of a surface stream or a body of surface water together with all tributary surface streams and bodies of water. • Watershed • The area whose runoff flows to a particular stream • Drainage Divides • a watershed/drainage basin boundary of higher elevation where water on the other side of the boundary flows to a different drainage basin. Watershed area is the land enclosed by its drainage divide

  3. Drainage basin, drainage divide, watershed, head waters, mouth (see Fig. 6.2 on p. 127) http://www.uwsp.edu/geo/faculty/ritter/geog101/textbook/fluvial_systems/stream_system.html

  4. (covers more than 1,245,000 square miles, includes all or parts of 31 states) www.mvn.usace.army.mil

  5. What causes streams to vary in size? • Drainage Area • Mississippi River • 1,245,000 square miles • Lumber River • 708 square miles • Climate • Precipitation/Evaporation Rates • Geology/Vegetation

  6. Stream Flow http://www.uwsp.edu/geo/faculty/ritter/geog101/textbook/fluvial_systems/channel_geometry_and_flow.html

  7. What factors are important to determine the flow of water in a river? • Cross-sectional area of channel • Velocity of water

  8. Discharge • Q = A * V • Q = discharge in feet3/sec • A = Cross-sectional Area in feet2 • (Channel Width x Water Depth) • V = Velocity of water in feet/sec

  9. The cross-sectional area (A) 10m wide by 2.5 m deep = 25 m2 And the velocity of flow (V = 5m/sec) are used to calculate discharge (Q) 25m2 x 5 m/sec = 125 m3/sec http://www.uwsp.edu/geo/faculty/ritter/geog101/textbook/fluvial_systems/channel_geometry_and_flow.html

  10. A Gage House-the most common source of river stage data. http://www.state.nj.us/drbc/gage/collected.htm

  11. FIG. A. Current meter being used to measure discharge. FIG. B. Current Meter. FIG. C. Stage/Discharge Rating Curve

  12. Comparison of Discharges • Mississippi River near St. Francisville, LA • Area Drained: 1,125,300 mi2 •  Mean Discharge: 543,400 ft3/sec • Lumber River near Lumberton • Area Drained 708 mi2 • Mean Discharge: 692 ft3/sec http://water.usgs.gov/nasqan/progdocs/factsheets/

  13. Capacity:How much can a stream carry? • Capacity is related to: • Velocity: • Discharge • which is related to the drainage area • Slope • Gradient

  14. How Do You Measure Gradient? Gradient = Change in Elevation / Distance: Elevation1 (Upstream) – Elevation2 (Downstream) Distance between points 1 and 2

  15. Headwaters High gradient Low Gradient Base level Profile of a typical stream showing the change in gradient downstream (see Fig. 6.5 on p.129) Modified from http://www.physicalgeography.net/fundamentals/10y.html

  16. Stream channel near the headwaters. http://www.physicalgeography.net/fundamentals/10y.html

  17. Stream channel near the middle of a typical stream profile. http://www.physicalgeography.net/fundamentals/10y.html

  18. Stream channel near the base level of a stream http://www.physicalgeography.net/fundamentals/10y.html

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