GEO 111 Ch. 18 Review

What is a braided stream and a meandering stream? What factors determine which pattern will dominate in a given stream?

braided stream: "braids of hair", up and down in discharge due to glaciers (bedload) meandering stream: erosion on outside of rock, helical flow (suspended load)

What are some of the common landforms of a braided and meandering stream? How are these landforms created by a stream?

braided: broad lowland valleys and wide sediment filled rift valleys meandering: on floodplains and over hard bedrock

A stream system has a collecting subsystem, a transport subsystem, and dispersing subsystem, where does each of these exist in a drainage basin? What features are found in each subsystem?

collecting subsystem: tributaries collect main water transport subsystem: main valley, carries water and sediment dispersal subsystem: mouth, deposited sediment

What is a dendritic stream pattern? How common is this pattern on Earth?

dendritic stream patter is branches similar to the limbs of trees, it occurs on similar sediments and rocks

What factors go into calculating stream power?

discharge x gradient x fluid density, measure of energy per unit of time in a stream

What are the three types of stream load?

dissolved: composed of ions in solution that can't be seen suspended: mud of silt and clay, makes water look muddy bedload: sand and gravel at the bottom of the stream (sand, gravel, boulders)

Explain what a drainage basin is (also called a watershed). What forms the boundary between two adjacent drainage basins? How is a drainage basin a system?

drainage basin: area drained by a stream system, area can be small or large, we define the area, a drainage divide (hill or mountain) for a boundary,

What processes determine and lead to stream erosion? What are pot holes? What is a slot canyon? How does each of these feature form?

pot holes: hole in bedrock of a streamed formed by abrasion by rotating pebbles

What factors determine other stream drainage patterns like radial, trellis, rectangular, and parallel? Be able to recognize these patterns in a diagram or map.

radial: pattern developed on single large peak trellis: developed in valley and ridge terrain rectangular: developed on jointed rocky terrain

What is a stage curve? How is it constructed? Why is it easier to measure stage than it is discharge?

stage curve: created by measuring stage and discharge at numerous times

What is a stream hydrograph? How can a hydrograph be used to predict flooding?

stage or discharge vs. time

What is stream discharge and units it is expressed in? How do we measure stream discharge in the field?

stream discharge: amount of water moving past a given point into a stream channel per unit time, measured by width x depth x velocity

What is stream gradient? How is it estimated? What are the units it is expressed in?

stream gradient: change elevation/distance (m/km or ft/mi), determines how much energy the stream has

What is stream power and why is it a useful concept in determining potential stream erosion?

stream power: discharge x gradient x fluid density, more power leads to erosion

Be able to define and differentiate the terms stream, river, channel, and floodplain

stream: any body of water which flows over a land surface river: major branches of a large stream system channel: troughs streams run through to flow long distances floodplain: flat area level with the top of a channel that lies on either side of the channel

What is the difference between downcutting and headward erosion? What is stream piracy? How is stream piracy determined by stream power?

the difference between downcutting and headward erosion is that downcutting is much less common and while headward erosion happens rapidly, downcutting is rare and catastrophic, stream piracy: streams captured by other streams

What are the processes by which water enters streams and lakes?

water runs downhill by precipitation, eroding rocks and creating valleys as it gathers into streams

Be able to recognize and explain the origin of the following stream landforms: waterfall, alluvial fan, stream terrace, and delta.

waterfall: rock is resistant to erosion, forms nick in rocks, picking at hard rock alluvial fan: stream dumps sediment in pile where river has no more stream power stream terrace: flat surfaces left up above river, old floodplains delta: mouth of stream comes out to ocean and dumps its sediment