Chapter 18

1. In which direction is the stream migrating? toward the left toward the right The stream’s position is not migrating.

2. Which type of stream is shown? straight braided meandering

3. Which type of stream is shown? straight braided meandering

4. Braided streams are more common in areas with: steady discharge. wide fluctuations in discharge. very steep slopes. None of the above.

radial dendritic trellis rectangular 5. Which drainage pattern is typical of streams that overlie horizontally bedded sedimentary rocks? radial dendritic trellis rectangular

6. Rectangular drainage networks typically develop over bedrock that is: mountainous. jointed. folded. horizontal.

7. The waterfall below is mainly the result of: erosion. deposition. both erosion and deposition.

8. Streams ___ sand grains at lower velocities and ___ them at higher velocities. erode; deposit deposit; erode transport; deposit erode; transport

9. A delta forms when water flowing through a stream reaches a: lake. ocean. mountain. A and B.

10. Given the same discharge, which stream will have the highest velocity? narrow, deep wide, shallow rough channel All will flow at the same velocity.

11. The recurrence interval of floods of a certain discharge is dependent on: climate of the region. width of the floodplain. size of the channel. All of the above.

12. What is the probability that a flood of 1500 m3/s will occur this year on this river? 90% 50% 20% 2%

13. How much greater is the discharge of a 10-year flood than an annual flood on this river? 10x 5x 3.6x 1.5x

14. True or False: A stream will erode or deposit sediment along its bed until it reaches a sustainable concave-upward profile. True False

15. What would happen to a river’s long profile if a dam were built halfway along its length? Nothing; the long profile would be unaffected. A small concavity in the profile would coincide with the location of the dam. A small convexity in the profile would coincide with the location of the dam. The entire long profile would reverse its orientation.

16. Which types of features can alter the local base level of a stream? layer of resistant bedrock movement of a fault block creation of a dam All of the above.

17. True or False: The gradient of a stream typically increases as one proceeds from its headwaters toward its mouth. True False

18. As river water moves from headwaters to base level within a fluvial system, its energy (~speed) ________ and the average sediment size it can carry __________. decreases; increases decreases; decreases increases; increase increases; decreases

19. The perennial source of water in most fluvial systems is: rainfall. snow/ice melt. groundwater. hurricanes.

20. What fluvial deposit is generated due to overflow of water from the stream channel to the floodplain? an alluvial fan point bar deposits natural levees deltas