Chapter 15. Streams
1. distinguish between a stream and a river.
2. understand the basics of the hydrologic cycle (evaporation, sublimation, condensation, precipitation, etc.) in delivering freshwater to terrestrial ecosystems.
3. list in order the areas in the world where water is stored (i.e., glaciers, groundwater. etc.)
4. recognize that streams are part of a larger system, the drainage basin.
5. be able to calculate a stream's gradient.
6. distinguish between ultimate and local base level of a stream.
7. calculate a stream's discharge when given its velocity and cross-sectional area.
8. relate how stream width, depth, velocity and discharge change from upstream to downstream sites.
9. distinguish between laminar and turbulent flow of water in a stream. Which is the most commonly found?
10. state where you can find the world's largest pothole.
11. describe how the bed load of a stream moves by saltation. How does this differ from suspended and dissolved load?
12. give the name of the river which is the largest based on: a) length b) discharge c) area of drainage basin
13. distinguish between a stream's capacity and competence.
14. explain why clay is nearly as difficult for a stream to lift off the bottom as far heavier gravel.
15. discuss why graded streams are uncommon and short-lived.
16. explain to disheartened honeymooners why they had better be sure to get to Niagara Falls in the near geologic future!
17. describe the set of conditions which would lead to development of a braided stream.
18. discuss the formation of characteristics of a meandering stream, such as riffles, pools, cutbanks, point bars, meander cutoffs, and oxbow lakes.
19. explain why some streams have no appreciable floodplain (like Tunkhannock Creek or nearby areas of the Susquehanna River), while some rivers have extensive ones.
20. explain how natural levees form.
21. compare the anatomy of a stream to that of a tree. How do tributaries resemble the branches? distributaries, the roots?
22. explain how underlying bedrock features help to determine an area's drainage pattern.
23. illustrate the manner in which a stream may 'steal' another drainage's water through stream piracy. Explain how his might have a significant impact on the fauna of the pirating stream.
24. distinguish between a permanent, intermittent, and interrupted stream.
25. determine a stream's order if given a topographic map.
Critical Thinking Questions and Activities:1. The Everglades are often called the 'River of Grass' flowing from Lake Okeechobee to Florida Bay. It has been greatly altered by ditching and draining, and diverting its waters to supply Miami. After reading an account of these changes, do you think that current costly efforts to restore the 'Glades are feasible or worthwhile?
2. Wilkes-Barre gets flooded frequently by the Susquehanna River. The area has responded by raising the artificial levees along the banks. Will this save the area? What are the implications to towns further downstream?
3. In the post-WWII era, the Army Corps of Engineers spent $zillions channelizing streams. Why? Why are they now unchannelizing many of these?
4. Obtain floodplain zoning maps for someplace near to your home. What is the basis on which zoning decisions were made? Which areas require flood insurance to secure a mortgage? What is the flood history of this area? What kind of restrictions apply to land use in floodplains?
5. Investigate the work of the Lackawanna River Corridor Association. What is their goal? Their problems? How successful are they in achieving them?
Resources:1. de Wet, Andrew. 1994. Integrating Field Observations with Physical and Computer Models in an Introductory Environmental Geology Course. Journal of Geological Education 42: 265-271.
2. Harbor, J. and K. McClintock. 1993. Teaching Applied Geomorphology with an Exercise in Urban Storm-Water Management and Erosion control. Journal of Geological Education 41: 38-42.
3. Mairson, A. 1994. The great flood of '93. National Geographic 185 (January): 44-87.
4. Smith, R. A., R. Alexander, and M. Wolman. 1987. Water-quality trends in the nation's rivers. Science 235 (March): 1607-15.
5. U. S. Geological Survey. 1996. Statewide Floods in Pennsylvania, January 1996. Fact Sheet 103-96.
Field Trip Opportunities:1. Visit Tunkhannock Creek to measure its width, depth and velocity to calculate discharge at several places. Evaluate its health by assessing its water chemistry, and fish and invertebrate communities.