Flooding ND Test 2
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What is a tributary?
where a small river flows into a big river
What is a confluence?
where two rivers join or meet
What is an estuary?
near mouth of river and is tidal
What is a drainage basin?
area of land that drains into one river and its tributaries
What is a watershed?
the dividing line between two drainage basins
What factors influence stream flow?
- sediment load
- base level
What is discharge?
amount of water passing a given point during a specific interval of time
What is the gradient?
- slope of the stream channel
- steeper at source of river, lower towards mouth
How does velocity affect stream flow?
determines how fast the river is moving
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
What is the base level?
- lowest level a stream can be eroded to
- level of the mouth of the river
What are the three types of channel patterns?
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
What are braided channels?
- sand and gravel bars that divide and unite a single channel
- wide and shallow
What are straight channels?
What are the causes of flooding?
- coastal flooding
- levee failures
- dam failures
How can you determine lag time from a graph?
- peak discharge subtracted by heavy rain fall
- bell curve
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
What is downstream flooding?
- large amounts of rainfall over an extended period of time over a large region
- affect large streams and tributary streams
What are the primary effects of flooding?
- injury/loss of life
- erosion and deposition of sediment related to loss of soil and vegetation
What are the secondary effects of flooding?
- short-term river pollution
What would you like to do?
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