Chapter 12 River Systems Flashcards
Erosion
Movement of soil and dirt from water, wind, and ice.
Deposition
Long distance relocation of rock material that has been removed.
Rills
Very small channel created from surface runoff.
Parallel rills form on steep slopes.
Alluvium
Rock material deposited by streams. Streams/rivers transport alluvium to oceans/lake
Sacramento River
Largest river in California
From the Clamammoth Mountains to San Joaquin Delta 445 miles long.
Provides over 1/2 of water to California’s population
Known as the “Nile of the West”
Discovery Park is the confluence of the American river and Sacramento river.
American River
Flows from the Sierra Nevada to Folsom Lake
Main source of drinking water
Rivers
Large stream
Channnels
Streams and rivers flow into depressions
Gradient
The steepness of a stream channel. Steeper near the source, gentler near the mouth
Drainage Patterns:
Dendritic
Most common drainage pattern is tree like
Drainage Patterns:
Trellis
Indicates parallel folding or inclined rock layers
Drainage Patterns:
Radial
Indicates a conical mountain or hill
Drainage Patterns:
Parallel
Indicates steep slopes
Drainage Patterns:
Rectangular
Indicates jointing or faulting
Braided Stream
Stream divided into multiple threads by bars of coarse alluvium. Located on valley floors
Alluvial Fan
The fan shape results from multiple storms
Braided stream patterns develop
Located in deserts
Delta
Accumulation of alluvium formed where a river empties into an ocean or lake
Local Example: Sac-San Joaquin Delta
Estuary
Water body at river’s mouth where freshwater meets seawater
Meandering Streams
Widely curved stream channel
Example: Sacramento’s Greenhaven/Pocket Area
Oxbow Lake
A lake in an abandoned meander
Nickpoint
An abrupt change in stream gradient. Waterfalls occur at nickpoint
Flood
Occur when streams overflow their channels
Flash flood
Occur in smaller watershed with steep gradients
Natural Levees
Formed from flooding
Artificial Levees
Embankments build on top of natural levees
Example: American River Bike Trail Levees
Natomas Basin
54,000 acre basin
42 mile ring of levees
Flood zone designation changed after Hurricane Katrina; bldg moratorium in 2008
US Army Corps of Engineers/SAFCA upgraded levees; 2015 bldg moratorium lifted
When is flooding is more likely to occur?
High rainfall and high water table
Which of the following is not used for flood control in Sacramento Area?
The Tower Bridge
