Flooding ND Test 2
Card Set Information
Flooding ND Test 2
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?
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
: 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?
How can you determine lag time from a graph?
peak discharge subtracted by heavy rain fall
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