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59 terms

science terms ch.5 running water and groundwater

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97.2
percent of water stored in the ocean
2.15
percent of water stored in ice sheets and glaciers
.65
percent of groundwater
hydrologic cycle
un-ending circulation of earths water supply
infiltration
a portion of water from precipitation that soaks in the ground
runoff
when the rate of rain fall exceeds earths ability to absorb it, the surplus water flows over the surface into lakes and streams
transpiration
when water that infiltrated the ground surface is absorbed by plants, which then release it into the atmosphere
evapotranspiration
when we can not distinguish between the amount of water that is evaporated and the amount that is transpired by plants
drainage basin
the land area that contributes water to a river system
divide
imaginary line seperating the drainage basin of one stream from the drainage basin of another
river (stream)
water flowing in a channel
laminar flow
very slow moving streams that flow in roughly straight paths that parallel the stream channel (opposite of turbulent flow)
turbulent flow
water moving in an erratic fashion that can be characterized as a swirling motion
velocity
the distance that water travels per unit of time
factors of velocity
gradient,shape,size,and roughness of channel
gradient
the slope of a stream expressed as the vertical drop of a stream over a specified distance.
channel
conduit that guides the flow of water
intermittent streams
streams that exibit flow only during "wet" periods
ephemeral streams
streams that carry water only occasionally after a heavy rainstorm
profile
a cross-sectioned view of a stream from its source area (head) to the mouth. (point downstream where the stream emptys into another body of water)
Discharge
the volume of water flowing past a certain point in a given unit of time
sheet flow
on barren slopes the flow of muddy water
dissolved load
stream load consists of material in solution
suspended load
stream load consists of material in suspension
bed load
stream load consists of material sliding or rolling along the bottom
competence
measures the max. size of particles it is able to transport
capacity
max. load it can carry
sorting
process by which particles of various sizes are separated
alluvium
the material deposited by a stream (occurs when material sinks or stops moving because the velocity is too low)
meander
sweeping bend (in a water body)
cut off
new shorter channel segment
oxbow lake
the abandon bend in a stream when a cut off forms
braided
showing a inter-woven appearance (form where large portion of the stream load consists of coarse material and the stream has a highly variable discharge)
base level
lower limit to how deep a stream can erode (commonly occur where the stream enters another body of water)
ultimate base level
sea level
(temporary) local base levels
lakes, resistant layers of rock, and main streams that act as a base level for their tributeries
Meander Scar
The remnants of a dried up oxbow lake
Braided Stream
Stream where the pattern is crossing over
Delta
Deposit of sediment into a larger body of water
Down cutting
when stream erosion occurs vertically
Rejuvenation
when a river takes on the properties of a younger river (becomes young again)
eddy
area on a river where water flows backwards, flowing upstream
floodplain
broad, flat valley floor covered with alluvium
cut bank
where a river erodes laterally into a bank
entrenched meander
meander that has experienced down cutting
point bar
formed by deposition on a river
alluvial fan
feature when a river comes out of a mountain and drops onto a valley floor (contain braided streams)
incised meanders
meandering channels that flow in steep, narrow, valleys
distributaries
smaller channels that divide off of the main channel and carry water away from the main channel.
natural levee
mound that is parallel to channels on both banks and is formed by repetitive floods
back swamps
marshes, formed behind levees and are characteristically poorly drained
yazoo tributaries
tributary streams that can not enter a river because of levees blocking the way. (flow parallel to river until they enter the main river later on)
dendritic
river pattern of irreguarly branching streams (most common river pattern)
radial
river pattern when streams diverge from a central area like spokes from a hub of a tire (typically develops on isolated volcanic cones and dominal uplifts)
rectangular
river pattern in which many right angle bends can be seen. Develops where bedrock faults or criss cross of series of joints
trellis
river pattern in which tributary streams are nearly parallel to one another
flood
when the discharge of a stream exceeds the capacity of its channel
.03
percent of water divided among lakes, streams, and the atmosphere
saltation
skips along bed of river , river can lift up but not for long