Card Set Information
What is discharge?
Total volume of water passing a point per unit time
m3/sec or ft3/sec
More land in contact with water = slower stream
If the velocities are the same, all of these streams have
the same discharge.
What’s the biggest river in the world in
terms of discharge?
How and where does a river deposit its
floodplains and natural levees, leaving
What are floodplains?
Flood plain are broad strips of land built up by
sediment deposited on either side of a stream
What are natural levees?
Natural levees occur where streams flood banks
and deposit sediment directly on top of banks.
What is the difference between braided and meandering streams?
Carry large quantities of sediment (often as bedload)
typically in deserts or glacial areas.
Channels get clogged with sediment and keep splitting and
Single, sinuous channel (meanders) which erode on
outside of each curve, and deposit a point bar on the
Ox-bow lakes form when parts of the channel are cut off and abandoned.
What is a delta?
River velocity drops as it
enters the ocean or a lake,
causing sediment to
accumulate as a delta
Long, finger-like sand
bodies, e.g. Mississippi
seaward margin of delta
consists of islands reworked by waves
continuously modified into
tidal sand bodies that parallel the direction of tidal flow
What’s an alluvial fan?
• Form where gradient suddenly flattens, usually when a
fault has been crossed
• Generally in arid climates with little vegetation to prevent
• Mudflows are common
What’s a flood? How dangerous are they?
Floods are any high flflows of surface waters that overtop normal confifinements or cover
land normally dry
Floods are the most devastating of all geologic agents -
exceeded only by plagues, world wars and the Holocaust in
loss of life.
What is the recurrence interval?
– Average time between floods of a given size
– 100 year flood
• occurs on average every 100 years
• 1% chance in every year to experience 100 year flood
How can we control floods?
Flood control structures
• flood walls
Legal flood control
• zoning to minimize
• prohibition of rebuilding;
• flood insurance