Geology Ch. 9

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Terms in this set (...)

Artificial levee
an embankment constructed to contain a stream at flood stage
base level
the level below which a stream cannot erode its bed; the ultimate base level is sea level
cutoff
a new channel that is formed when a stream cuts through a very tight meander
delta
the nearly flat land formed where a stream empties into a body of standing water, such as a lake or the ocean
discharge
the volume of water, usually expressed in cubic feet per second, that passes a given point within a given period of time
drainage basin
the tract of land that contributes water to a particular stream, lake, reservoir, or other body of surface water
drainage divide
the boundary between two drainage basins
fan
triangular or fan-shaped deposit of sediment where a stream or gully deposits sediment on a less-sloped plain; there the sediment cannot be transported and so accumulates
flood frequency
the average time interval between floods that are equal to or greater than a specified discharge
floodplain
the portion of a river valley adjacent to the channel that is built of sediments deposited during times when the river overflows its banks at flood stage
floodwall
a heavily reinforced wall designed to contain a stream at flood stage
gradient
the slope of a streambed usually expressed as the amount of drop per horizontal distance in meters per kilometer
hydrograph
a graph of the stage (height) or discharge of a body of water over time
infiltration
the movement of water, including rain and snowmelt, into the soil surface
inundation
flooding by water
meander
one of a series of sinuous curves in the course of a stream
natural levee
embankments of sand or silt build by a stream along both banks of its channels; they are deposited during floods when waters overflowing the stream banks deposit sediment as they slow down
oxbow lake
a crescent-shaped lake formed along a stream course when a tight meander is cut off and abandoned
point bar
a deposit of sand and gravel found on the inside curve of a meander
precipitation
the separation of a solid substance from a solution by a chemical reaction
recurrence interval
the return period of an event, such as a flood or an earthquake, of a given magnitude. For flooding, it is the average interval of time within which a given flood will be equaled or exceeded by the annual maximum discharge
regulatory floodplain
the part of a floodplain that is subject to federal government regulation for insurance purposes
riparian
pertaining to or situated on the bank of a body of water, especially of a river