Rivers, floods and management

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  • Created by: Iona
  • Created on: 08-05-14 12:20
Hydrological cycle
The continuous flow of water pouring into a drainage basin (inputs), being stored or moved into the channel (processes and stores) and evapotranspiring (outputs)
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Precipitation
All forms of moisture entering the atmosphere (rain, snow, hail)
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Interception
This occurs when the precipitation hits an object, albeit plants, concrete, buildings, before making contact with the soil
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Infiltration
The absorption of precipitation into the ground. Influenced by soil type, soil structure and how saturated the ground is
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Surface Run-Off
Water flows overland, occurs mostly over arid (desert) land, or saturated land
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Percolation
Water soaks through soil and into water table
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Groundwater Flow
Water soaks slowly just below the water table and in through some rocks (permeable)
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Evapotranspiration
Joint processes of evaporation and transpiration
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Stemflow
Water trickles down a stem or tree trunk
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Throughflow
water moves downwards through the soil, and moves quicker in pipes or cracks in the soil
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Drainage Basin
The area surrounding a channel in which the rain falling on the land flows into that river (also known as a river's catchment)
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Watershed
The boundary of a drainage basin
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Water Table
This is when the area is saturated and cannot take any more precipitation
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Source
An origin of a river channel (usually in mountains)
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Tributary
Also known as an affluent, it is a stream that ends up meeting the main river channel
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Confluence
Tributaries and the main river channel meet at a confluence. Think of it like joining a motorway fromm a side road
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Channel
The course of transportation for a river
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Annual Regime
The annual pattern of rainfall
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Hydrograph (strorm)
Shows a variation in a river's discharge over a period of time, usually presented during a storm
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Discharge
Amount of water flowing in a river (volume of water moving in a stream during a given time interval)
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Cumecs
It is a measurement (a cubic metre per second) to measure the flow of a river
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Lag Time
The delay between peak rainfall and peak discharge.
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Flash Response
Flash responses lead to a very abrupt rise in discharge over a short period of time. ie. A storm
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Lag Response
No "abrupt rising limb", slower. Has a longer Lag time and lower peak discharge
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Peak Flow
Indicates highest flow in the channel
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Base Flow
Groundwater flow that feeds into rivers through banks and beds
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Deforestation
The chopping down of trees for industrial use or for building properties there.
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Spring (source)
Can be formed through seepage springs (from underground), fracture springs (through the bedrock), tubular springs (form caves underground)
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Upper Course
Gradient is steep. Source is high above sea level. Has lots of potential energy, not alot of kinetic energy
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Middle Course
Gradient decreases, and potential energy converts to kinetic energy, and the river gains velocity
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Lower Course
Has not very much potential energy but there is lots of kinetic energy. It flows rather fast
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Valley
An elongated lowland between ranges of mountains, hills, or other uplands, often having a river or stream running along the bottom.
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Interlocking Spurs
Occurs in the upper course, the hills tend to jut out into the river valley resulting in a staggered formation, interlocked together somewhat like the teeth of a zip
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Mass Movement
A movement of a selection of material that suddenly drops, or moves (rock falling off a cliff, or a mudslide)
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Waterfall
Occur when there is a sudden change in gradient of the river as it flows downstream. Are a result of a plateau, rejuvenation and resistant band of rock
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Plateau
Flat, elevated landform that rises sharply above the surrounding area on at least one side. Plateaus occur on every continent and take up a third of the Earths land.
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Plunge Pool
A dip/depression formed at the base of a waterfall due to erosional powers of water
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Rapid
Areas of shallow, fast moving water in a stream
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Gorge of Retreat
A gorge is a narrow valley with steep, rocky walls located between hills or mountains
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Potholes
Cylinder-shaped holes formed into the rocky bed of a river by high velocity water. The pebbles being transported get stuck in the holes and as a result they grind the hole even deeper and wider
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Floodplain
Formed as a result of erosion and deposition. They are relatively flat patches of land either sides of rivers
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Levee
When a flood occurs in the middle/lower course of a river, material is deposited either side of the channel. Little banks are then formed (Levees)
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Bluff
A bluff is a steep cliff, or wall of rock or soil. Most bluffs border a river or its flood plain
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River terrace
A narrow, flat piece of ground that runs parallel to the river on either side, above the level of the floodplain. They are usually created following a fall in base level
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Meander
A sinuous bend in a river, caused by pools and riffles.
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Oxbow Lake
Features of erosion AND deposition. Rounded shaped lake, seperate from the main river channel. The water stays still (stagnant) and the lake gradually becomes marshy. It is then known as a meander scar.
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Braiding
This is when the channel is forced to split pathways. Usually occurs in rivers that have lots of sand and gravel. The mini channels are separated by deposited islands.
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Eyot
An island of deposition
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Backswamp
The section of a floodplain where deposits of fine silts and clays settle after a flood. Backswamps usually lie behind a stream's natural levees.
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Stagnant water
Water that stays still and usually causes silt to settle, causing it to form a marshy land area
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River Cliff
Water in the channel moves in a spiral pattern. Water moving along the surface of the river near the outer bank tends to do so at a greater speed than water moving against the inner bank.The outer bank gets eroded by the force&velocity of the waves.
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Slip off Slope
A slope in the water that is slippery so it is difficult to stand on
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Point Bar
The inner bank of a meander, which is gently sloping
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Delta
Located at mouth of river. In the form of an Arcuate delta, Bird's foot delta and a Cuspate delta
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Arcuate delta
Most commonly recognised. It has a curving shoreline and a branched pattern of drainage. It is a braiding affect.
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Dendritic Patterning
Dendritic patterning looks like a tree branch, or split ends on your hair.
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Bird's Foot Delta
eg. Mississippi. Looks like a bird's claw. Spread out claws merge into the sea.
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Cuspate Delta
There is one singular channel entering the sea which is in a straight pathway, which has a curved island of deposition surrounding either sides of it which connect to the land (like two triangles of beaches).
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Flood
Occurs when a river's discharge exceeds the capacity of it's banks and the water overflows. The extent at which it overflows depends on the site, urbanisation, deforestation etc that has occured there.
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Flood Relief Channel
An alternate pathway for water to flow if the water levels rise unnecessarily high in the banks
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Advantages of Flood Relief Channels
They take the pressure off the main channels when floods are likely therefore reduce flood risk.
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Disadvantages of Flood Relief Channels
It can be hard find land to build relief channels, they are expensive and when empty can become areas to dump rubbish, etc. If river levels rise significantly it is also possible for relief channels to flood as well.
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Canalisation
Act of physically altering the flow of a river to make it straight.
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SUDS (Sustainable Urban Drainage Systems)
Sustainable drainage systems aim to alleviate Urbanisation issues by storing or re-using surface water at source, by decreasing flow rates to watercourses and by improving water quality.
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Other cards in this set

Card 2

Front

All forms of moisture entering the atmosphere (rain, snow, hail)

Back

Precipitation

Card 3

Front

This occurs when the precipitation hits an object, albeit plants, concrete, buildings, before making contact with the soil

Back

Preview of the back of card 3

Card 4

Front

The absorption of precipitation into the ground. Influenced by soil type, soil structure and how saturated the ground is

Back

Preview of the back of card 4

Card 5

Front

Water flows overland, occurs mostly over arid (desert) land, or saturated land

Back

Preview of the back of card 5
View more cards

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