chapter 17 flowing water Flashcards
floodplains
the areas of flat land near a stream that experiences flooding on a regular basis
stream
channel in which water flows down hill by the force of gravity
drainage basin
a geographic region drained by a single trunk stream and its tributaries
trunk stream
single large stream into which smaller tributaries merge
tributary
stream that joins with other streams to form a larger stream
drainage divide
a ridge or highland that separates drainage basins and defines their boundaries
continental divide
a ridge or highland that separates drainage systems that empty into ocean basins
internal drainage
drainage basins with no outlet to the ocean
stream order
a system that ranks streams based on the number of tributaries flowing into them
first order stream- no tributaries
intermittent stream
a stream that runs dry during part or most of the year
ephemeral stream
a stream that flows briefly after heavy rainstorms
permanent stream
a stream that flows all year
exotic stream
a permanent stream that originates in a humid region and flows through an arid region ex. nile river
fluvial erosion
erosion by running water
headward erosion
the process by which a stream channel lengthens upslope through time, forming new rills (newly forming stream channels) and gullies (what rills develop into) by fluvial erosion
stream discharge
the volume of water flowing past a fixed point within a stream channel
calculating stream discharge
Q=A X v
stream discharge- Q
stream channel area- A
velocity- v
abrasion
the process by which movement of one material wears away another material
stream load
material that moves within stream channel
three types of stream loads
dissolved- soluble minerals that are carried in solution by a stream
suspended- small particles that remain suspended in flowing water or wind
bed- material in stream channel that is too heavy to become suspended in the current
saltation and traction
saltation- sand grains move in a bouncing or hopping motion
traction- larger rocks are moved by a dragging or tumbling motion
stream competence and stream capacity
stream competence- size of fragments a stream can transport
stream capacity- total amount of material that a stream can carry
stream gradient
refers to the steepness of a stream, or the drop in elevation of the stream channel in the downstream direction
base level
lowest level a stream can reach
knickpoint
a location where there is an abrupt increase in stream gradient over a short distance
escarpment
long cliff face or steep slope
plunge pool
bowl at the base of a waterfall created by abrasion of circulating rocks
stream rejuvenation
a process in which a stream gains erosional energy as its base level is lowered relative to its drainage basin
stream piracy
the diversion of one stream into another as headward erosion merges the two streams
alluvium
sediments deposited on a floodplain
aggradation
the buildup of sediments within a stream bed and along its floodplain
braided streams
streams that form intertwining channels around sediments in the stream bed
alluvial fan
a gently sloping accumulation of sediment deposited at the base of a mountain by an ephemeral stream in arid regions
thalweg
the fastest flowing portion of the stream
cut bank
the side of a stream where erosion exceeds deposition
point bar
an accumulation of silt, sand, and gravel on a stream bank that forms where deposition exceeds erosion
oxbow lake
a water filled abandoned channel that results when a meander is cut off from stream channel
reservoir
an artificial lake created by a dam
delta
an accumulation of sediments that forms where a stream reaches base level
distributaries
a branching network of small streams in a delta
subsidence
the lowering of land evolution through the compaction of sediments
