Rivers Key words

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  • Created by: sarah
  • Created on: 22-04-14 14:14
Drainage Basin
The catchment area from which a river system obtains its supplies of water.
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Hydrological cycle
The circulatory system by which water is transferred between the oceans and the land masses. Evaporation from the sea, lakes and the land surface and transpiration from vegetation produces water vapour in the atmosphere.
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Watershed
the boundary that separates one drainage basin from another
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Impermeable
A rock that neither absorbs water nor allows it to pass through. e.g. Granite
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Precipitation
Water in any form which falls from the atmosphere to the surface of the Earth. e.g. rainfall , snow , sleet and hail
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Evaporation
The process by which liquid water is transformed into water vapour, which is a gas.
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Transpiration
The process by which water is lost from a plant through the stomata its leaves.
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Evapotranspiration
is the total amount of moisture removed by evaporation and transpiration
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interception
The process by which raindrops are prevented from falling directly on to the soil surface by the presence of a layer of vegetation. e.g. by plant leaves
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Depression (surface) storage
Water sored temporarily on the surface of the ground e.g. puddles
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Soil moisture storage
moisture content of the soil
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Ground water storage
water that collects underground in the pore spaces in soil and rock
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Base (groundwater) flow
The movement of groundwater seeping slowly towards the bed of the river.
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Percolation
The downward vertical movement of water within a soil. (The water then enters the groundwater store)
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Through flow
It is the movement of water beneath the surface, which moves towards the river
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infiltration
The movement of water from the surface into the soil
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Overland flow (surface run off)
Is the movement of water along the surface of the ground towards the river channel
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Aquifer
permeable rock that can store and transmit water beneath the surface
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Water table
The upper boundary of the saturated (waterlogged) rock
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Discharge
the volume of water in a river passing a measuring point in a given time
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Regime
is the term used to describe the (normally) annual variation in discharge
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Abstraction of water
The removal of water from drainage basin e.g. reservoir or from aquifers
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Antecedent rainfall
is the rainfall that fell in a previous period
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Antecedent soil moisture
The existing moisture content of the soil as a result of previous rainfalls
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Hydrographs
A graph which shows variations in river discharge, in cubic metres per second, over a period of time. (often after just one rainfall)
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Relief
The difference between the highest and lowest elevations in an area.
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Drainage density
Total amount of drainage systems compared with the size of an area e.g. tributaries
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Tributary
A river that flows into another river
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Long profile
illustrates the changes in the altitude of a river’s course from its source along its channel to its mouth
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Bed load
Particles along the bed of a river e.g. sands, gravels and pebbles
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Waterfall
a steep fall of river water where its course is markedly and suddenly interrupted
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Gorge
a deep, steep-sided and narrow valley usually occupied by a river
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floodplain
that part of a valley floor which a river may flood from time to time
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Meanders
A bend in the river
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Ox-bow lakes
a horse-shoe shaped lake separated from an adjacent river
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levee
that part of the bank of a river that is raised higher than the floodplain
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Weathering
The disintegration and decomposition of rocks by the combined actions of the weather, plants and animals.
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Mass movement
is the downslope movement of weathered material under the influence of gravity
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Protruding strata
layer or a series of layers of rock which extend above the surface of the water
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Hydraulic action
river erotion due to sheer force of the water
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Abrasion
The sandpaper effect of rocks rubbing against surfaces eroding them
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Attrition
When particles suspended in the water knock against each other, eroding them and causing them to decrease in size and become more rounded
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Suspension
Particles are carried by the water while being suspended in it (not touching bed)
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solution
The movement of dissolved particles in the water
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saltation
The “hopping motion”, by which particles are lifted upwards and forwards before returning back to the river bed.
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Traction
The movement of large material that roles along the riverbed
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Competence
the diameter of the largest particle that a river can carry for a given velocity
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Deposition
The laying down of sediment
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Base Level
is the lowest limit to which erosion can take place. For rivers, the ultimate base level is regarded as sea level. Exceptions occur when rivers drain into inland basins which are themselves below sea level.
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bankfull
is when the channel of a river contains all the water that it can carry, i.e. its carrying capacity is at a maximum. If a river exceeds its bankfull discharge , then flooding occurs.
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alluvium
s the sediment deposited by a river
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Braiding
sub-dividing of a river channel, a characteristic of a river with variable discharge
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capacity
the largest amount of load that a river can carry for a given velocity
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channel efficiency
s measured by the hydraulic radius , which is defined as the ratio of the cross-sectional area divided by the length of the wetted perimeter . The higher the ratio, the more efficient the channel and the smaller the loss of energy due to external fri
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channelisation
is the modification of river channels for the purposes of flood control , land drainage, navigation and the reduction or prevention of erosion . River channels may be modified by engineering works including realignment or by maintenance measures such
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corrosion
river is eroded by transported particles grinding on banks and beds
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delta
an area of deposition at the mouth of a river
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estuary
the area of a lower river, or mouth, which is affected by tidal change. Estuaries are produced by the post-glacial rise of sea level and drowning of former lower valley areas.
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flooding
inundation of land not normally under water
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floodplain
extensive flat land adjacent to river that is prone to flooding
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graded profile
smooth concave long profile of a river that has achieved a state of equilibrium with its environment (no excess energy for erosion)
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hard engineering
commonly built structures such as concrete walls designed to restrict natural processes
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helical flow
a downstream spiralling of water flow associated with meandering channels.
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hydraulic radius
measurement of channel efficiency calculated as a cross-sectional area/wetter perimitor
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incised meyander
steep-sided meyander formed during a period of significant down-cutting following rejuvenation
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kinetic energy
when water moves downhill, potential energy is converted to kinetic energy and used to do "work"
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knick point
when a river is rejuvenated, adjustment to the new base level starts at the sea and gradually works its way up the river course, the point of change to the existing profile being known as the knickpoint.
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pot hole
circular hollow/depression formed by erosion in bedrock on a river bed
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point bar
a gently sloping bank on the inside of a meander composed of sands and gravels
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peak flow
s the maximum level of discharge in a storm hydrograph largely resulting from the arrival of fast overland flow into the channel system.
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pools and riffles
on the meanders of a river, the pools are the areas of deeper water, whereas the riffles are the shallower parts. The pool represents the area where the energy of a river builds up due to a reduction in friction, but across the riffle energy is dissi
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rapids
series of relativly amall "steps" in the long profile of a river forming a stretch of turbulent white water
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rejuvenation
a fall in sea level relative to the level of the land, or a rise of the land relative to the level of the sea enables a river to revive its erosional activity. The river will adjust to the new base level, at first in its lowest reaches, and then prog
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river restoration
restoring a river to its natural corse of following earlier intervention e.g chanel straightening,
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river terrace
a remnant of a former floodplain , which after rejuvenation of the river has been left at a higher level.
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soft engineering
management aproaches that have minimal effects on the environment and aim to work with natural proceeses
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water balance
audit of water based on the equation percipitation = runoff + evapotranspiration =/- soil moisture
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wetted perimeter
is the total length of a river’s bed and banks that are in contact with water when viewed as a cross-section
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Other cards in this set

Card 2

Front

The circulatory system by which water is transferred between the oceans and the land masses. Evaporation from the sea, lakes and the land surface and transpiration from vegetation produces water vapour in the atmosphere.

Back

Hydrological cycle

Card 3

Front

the boundary that separates one drainage basin from another

Back

Preview of the back of card 3

Card 4

Front

A rock that neither absorbs water nor allows it to pass through. e.g. Granite

Back

Preview of the back of card 4

Card 5

Front

Water in any form which falls from the atmosphere to the surface of the Earth. e.g. rainfall , snow , sleet and hail

Back

Preview of the back of card 5
View more cards

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