Flooding ND Test 2

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Flooding ND Test 2
2013-11-11 18:11:18

test 2
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  1. What is a tributary?
    where a small river flows into a big river
  2. What is a confluence?
    where two rivers join or meet
  3. What is an estuary?
    near mouth of river and is tidal
  4. What is a drainage basin?
    area of land that drains into one river and its tributaries
  5. What is a watershed?
    the dividing line between two drainage basins
  6. What factors influence stream flow?
    • discharge
    • gradient
    • velocity
    • sediment load
    • base level
  7. What is discharge?
    amount of water passing a given point during a specific interval of time
  8. What is the gradient?
    • slope of the stream channel
    • steeper at source of river, lower towards mouth
  9. How does velocity affect stream flow?
    determines how fast the river is moving
  10. What is the sediment load?
    • materials transported along with water
    • types: bed-load moves along bottom; suspended-load silt and clay carried in water; dissolve-load chemical solutions moved in the water
  11. What is the base level?
    • lowest level a stream can be eroded to
    • level of the mouth of the river
  12. What are the three types of channel patterns?
    • straight
    • meandering
    • braided
  13. What are meandering channels?
    • each curve has a cut bank towards the outside
    • deposits more sediment on the inside
    • faster on outside, slower on inside
    • stream shifts position
  14. What are braided channels?
    • sand and gravel bars that divide and unite a single channel
    • wide and shallow
  15. What are straight channels?
  16. What are the causes of flooding?
    • precipitation
    • coastal flooding
    • levee failures
    • dam failures
  17. How can you determine lag time from a graph?
    • peak discharge subtracted by heavy rain fall
    • bell curve
  18. What is upstream flooding?
    • large amounts of rainfall over a short period of time within a small area
    • water rises quickly and also goes away quickly as the storm passes
  19. What is downstream flooding?
    • large amounts of rainfall over an extended period of time over a large region
    • affect large streams and tributary streams
  20. What are the primary effects of flooding?
    • injury/loss of life
    • erosion and deposition of sediment related to loss of soil and vegetation
  21. What are the secondary effects of flooding?
    • short-term river pollution
    • hunger/disease
    • homelessness