14.7: Review and Additional Resources

Review

Figure \(\PageIndex{1}\)

Review and assess your learning. Start with the "Important Terms and Concepts" to ensure you know the terminology related to the topic of the chapter and concepts discussed. Finally, test your overall understanding by taking the "Self-assessment quiz".

Important Terms and Concepts

• drainage basin

  fundamental unit of study for fluvial processes

• watershed

  fundamental unit of study for fluvial processes

• perennial stream

  flow all year

• tributary stream

  small streams that enter into the main stream

• intermittent stream

  only flow during wetter times of the year

• interfluve

  The upland between tributaries

• drainage divide

  represents the boundary between adjacent drainage basins and determines into which basin precipitation flows

• exotic stream

  those that originate in a humid region but flow through an arid region

• Davisian Cycle of Erosion

  a theory of landscape development that describes a cycle of erosion which shapes the land surface

• Dynamic equilibrium theory

  equilibrium state is determined by the balance between inputs and outputs from the system. Over time, the channel achieves an equilibrium state between inputs (water) and outputs (sediment)

• dendritic drainage pattern

  the most common form and looks like the branching pattern of tree roots

• parallel drainage pattern

  form where there is a pronounced slope to the surface. A parallel pattern also develops in regions of parallel, elongate landforms like outcropping resistant rock bands

• trellis drainage pattern

  look similar to their namesake, the common garden trellis

• rectangular drainage pattern

  found in regions that have undergone faulting. Streams follow the path of least resistance and thus are concentrated in places were exposed rock is the weakest; makes sharp bends and enter the main stream at high angles.

• radial drainage pattern

  develops around a central elevated point. This pattern is common to such conically shaped features as volcanoes.

• centripetal drainage pattern

  opposite of the radial as streams flow toward a central depression

• deranged drainage pattern

  develop from the disruption of a pre-existing drainage pattern

• accordant stream

  correlated with the structure and relief over which they flow

• discordant stream

  rocks over which they flow are either antecedent or superimposed

• antecedent stream

  flowed across bedrock structures prior to uplift

• superimposed stream

  appear to be superimposed over the rock layers that they presently flow over

• cross-sectional area

  determined by multiplying channel depth by channel width along a transverse section of the stream

• wetted perimeter

  the portion of the channel that is "wet"

• flow velocity

  how fast the water is moving through a cross-section

• discharge

  the volume of water passing through a particular cross-section in a unit of time, measured in units like cubic meters per second or cubic feet per second

• hydrograph

  a graphical way of portraying the change in discharge over time, and how it relates to inputs of water and the environment in which the stream is located

• rising limb (hydrograph)

  the part of the graph where it rises to a peak

• recessional limb (hydrograph)

  where the graph declines back to its base flow

• straight channel

  relatively straight; rarely is a channel perfectly straight in nature

• meandering channel

  one that takes twists and turns over its length

• braided channel

  created when a stream channel is divided into several smaller ones by the accumulation of in-channel deposits

• sinuosity ratio

  the distance between two points on the stream measured along the channel divided by the straight line distance between the two points

• stream (channel) slope (gradient)

  the difference in elevation between two points on a stream divided by the distance between them measured along the stream channel.

• stream erosion

  the detachment of material from the bed or sides of the channel

• stream transportation

  the movement of earth material by water

• traction

  a scooting and rolling of particles along the bed

• saltation

  a bouncing-like movement

• suspended load

  comprised of sediment suspended and transported through the stream

• bed load

  that which is moved across the bed of the channel

• solution (dissolved) load

  comes primarily from groundwater seepage into the stream. Ions in solution also come from the solution of materials that line the channel

• stream deposition

  sediment moving through the stream accumulate on the bed

• floodplain

  the relatively flat area that borders a stream which is periodically inundated with water during high flow periods

• natural levee

  a narrow ridge of alluvium deposited at the side of the channel

• back swamp

  located some distance away from the stream channel on the floodplain; important "sponges" that retain water that might cause severe flooding downstream.

• meander

  a bend in a stream

• point bar

  forms on the inside bank of a meander and rising from the channel as an accumulation of alluvium

• alluvium

  sediment carried by stream

• bar and swale topography

  a succession of bars with intervening swales

• neck

  the upland between opposing meanders of a stream

• cutoff

  occurs when the neck between river meanders is eroded away and the meanders join to shorten the length of the channel

• oxbow lake

  A river cut-off; typically crescent shaped - like that of an oxbow

• meander scar

  remnants of the oxbow

Additional Resources

Use these resources to further explore the world of geography

Focus on The Physical Environment: "Floods: Using Satellites to keep Our Heads above Water. (NASA Earth Observatory)

Physical Geography Today: Water Watch - USGS

Connections: Army Corps Project Pits Farmland Against Flood Threat. (NPR 2015) Flood protection pits farmland against local communities.

Active Learning: Virtual River (Cal State-LA)

Multimedia

"Running Water I: Rivers, Erosion and Deposition" (Annenberg/CPB:) Earth Revealed "Rivers are the most common land feature on Earth and play a vital role in the sculpting of land. This program shows landscapes formed by rivers, the various types of rivers, the basic parts of a river, and how characteristics of rivers — their slope, channel, and discharge — erode and build the surrounding terrain. Aspects of flooding are also discussed." Go to the Earth Revealed site and scroll to "Running Water I: Rivers, Erosion and Deposition". One-time, free registration may be required to view film.

"Running Water II: Landform Evolution" (Annenberg/CPB) Earth Revealed "The Colorado River is a powerful geologic agent — powerful enough to have carved the Grand Canyon. This program focuses on how such carving takes place over time, looking at erosion and deposition processes as they relate to river characteristics and type of rock. The evolution of rivers is covered, along with efforts to prevent harmful consequences to humans." Go to the Earth Revealed site and scroll to "Running Water II: Landform Evolution". One-time, free registration may be required to view film.

"Work of Rivers" (National Archives/Google) 1935 video by the Department of Interior. Interesting from a historical perspective on geomorphic theory (eg. Davisian theory) at the time.

Three Gorges" In this July 8, 2002 segment of All Things Considered NPR's Rob Gifford reports from the Yangtze River in central China as the Three Goreges Dam was nearing completion. (Real Media)

Readings

Flood: Using Satellites to keep our Head Above Water (NASA EOS)

Web Sites

Water Resources of the United States (USGS)