2. What is a Drainage Basin? 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 Watershed  The area whose runoff flows to a particular stream Drainage Divides 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. www.mvn.usace.army.mil ( covers more than 1,245,000 square miles, includes all or parts of 31 states )

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

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

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

9. Discharge Q = A * V Q = A * V  Q = discharge in feet 3 /sec  A = Cross-sectional Area in feet 2  (Channel Width x Water Depth)  V = Velocity of water in feet/sec

10. The cross-sectional area (A) 10m wide by 2.5 m deep = 25 m 2 And the velocity of flow (V = 5m/sec) are used to calculate discharge (Q) 25m 2 x 5 m/sec = 125 m 3 /sec http://www.uwsp.edu/geo/faculty/ritter/geog101/textbook/fluvial_systems/channel_geometry_and_flow.html

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

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

13. Comparison of Discharges Mississippi River near St. Francisville, LA Mississippi River near St. Francisville, LA  Area Drained: 1,125,300 mi 2  Mean Discharge:543,400 ft 3 /sec Lumber River near Lumberton Lumber River near Lumberton  Area Drained708 mi 2  Mean Discharge:692 ft 3 /sec http://water.usgs.gov/nasqan/progdocs/factsheets/

14. Capacity: How much can a stream carry? Capacity is related to: Capacity is related to:  Velocity:  Discharge which is related to the drainage areawhich is related to the drainage area  Slope GradientGradient

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

16. 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 Base level HeadwatersHigh gradient Low Gradient

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

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

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