geology final exam - running water

floodplain

a broad flat valley covered with alluvium caused by continuous lateral erosion

local base level

a lake, another stream or a reservoir

dissolved load

acquired from a stream's bed and bank where soluble rock is present (limestones)

delta

alluvial deposit where a river flows into a lake or the ocean and causing the shoreline to build outward into the lake or sea (progradation)

running water

any surface water moving from higher to lower areas as runoff in response to gravity

how streams are shaped

changing shapes of the channel, erosion, deposition

deranged drainage

characterized by irregularity, with streams flowing in and out of swamps and lakes, recent drainage system not fully developed

potholes

circular to oval depression formed where swirling currents with sand and gravel eroded the rock

alluvium

collective term for all detrital sediments transported and deposited by running water

hydrologic cycle

continuous recycling of water from the oceans, through the atmosphere to the continents and back to the ocean (involve evaporation, condensation, precipitation, runoff)

tide dominated delta

continuously modified tidal sand bodies that parallel the direction of tidal flow

2nd step to predicting and controlling floods

control flood, construct dams that impound reservoir, build levee along stream beds, construct floodway channel to divert part of the excess water in a stream around a city or economic center, construct flood walls

incised meanders

deep meandering canyon cut into bedrock by a stream or river, stream cannot erode laterally, thus occupies the entire width of the canyon floor

wave dominated delta

distributary channels constituted of islands reworked by waves

stream terrace

erosional remnant of a floodplain that formed when the stream was flowing at a higher level, fairly flat upper surface and steep slope descending toward the valley

alluvial fans

fan-shaped deposit that accumulates along steep mountain fronts

downcutting

forms a v shaped valley

natural levees

gently sloping structures that parallel a river channel, created by repeated floods

parameters affecting channel flow

gradient, velocity, discharge

oxbow lake

horseshoe shaped lakes produced by meanders ends connecting and detaching from the meandering stream

where velocity is greater

in the middle of channels, in deeper semicircular channels, in smooth channels, downstream

annular drainage

incomplete, concentric rings that are connected by short channels, forms along domes that have alternating rock types at the surface

braided stream

intricate network of dividing and rejoining broad and shallow channels separated from another by sand and gravel bars, sediments supply exceeds the transport capacity of running water

bed load

larger particles (sand and gravel) transported along the bed

stream dominated delta

long finger like sand bodies deposited in a distributary channel that prograde far seaward

base level

lowest limit to which a stream can erode

velocity

measure of distance traveled per unit of time expressed in m/sec, varies across a channel width as well as across its length

solid load

moves as suspended load or bed load

dendritic drainage

network of channels resembling tree branches, gently sloping surfaces, homogenous erosion

trellis drainage

network of nearly parallel main streams with tributaries joining them at right angles, layering of resistant/nonresistant rocks that have been tilted and eroded to form landscape alternating resisting ridges and valleys

1st step to predicting and controlling floods

prediction, monitor stream and evaluate their past behavior, anticipate flood of a given size in a specific period

corrosion

process in which rock is gradually dissolved by the flowing of water

drainage patterns

regional arrangement of channels in a drainage system (dendritic drainage, rectangular drainage, trellis drainage, annular drainage, radial drainage, deranged drainage)

quarrying

removal of blocks from the bed aided by fracturing

abrasion

rock is worn smooth by the impact of sediments being transported

ultimate base level

sea level

how channel flows receive water

sheet flows, soil moisture, groundwater, rainfall

meandering stream

single sinuous channel with broadly looping curves known as meanders, transports primarily mud, sand and occasionally gravel

gradient

slope over which a stream or river flows expressed in m/km or ft/mi

suspended load

smallest particles (clay) carried by running water are kept suspended by turbulence

graded stream

stream that has an equilibrium profile in which a delicate balance exists among gradient, discharge, flow velocity, channel characteristics, and sediments load so that neither significant deposition or erosion takes place within its channel

radial drainage

streams flow outward in all directions from a central high point, such as a volcano

drainage system/basin

surface area drained by stream or river and its tributaries, and separated from an adjoining system by a divide (high topographic separating adjacent system)

channel flow

surface runoff is confined to depressions that vary in size from tiny rills that meet to form gullies which to join to form a river channel

rectangular drainage

tributaries join larger channels at right angles, bedrock is crisscrossed by a series of joints or faults

discharge

volume of water in a stream or river moving past a specific point in a given interval of time expressed in m3/sec or ft3/sec