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AS Geography key words > Rivers,floods And Management > Flashcards

Rivers,floods And Management Flashcards

1
Q

Abrasion

A

The scraping,scouring,rubbing,grinding and drilling action of materials being moved by a river

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2
Q

Attrition

A

The collision of one piece of a rivers load with another breaking off bits of rock in the proces. Makes rocks rounder and smaller

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3
Q

Base level flow

A

The lowest limit to which erosion can take place, usually sea level

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4
Q

Braiding

A

Occurs when a heavily loaded river rapidly loses energy and rocks are deposited mid channel

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5
Q

Channel cross profile

A

The view of a river channel from one side of the channel to the other

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6
Q

Cumec

A

The unit of discharge measured in m3 s-1

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7
Q

Deforestation

A

The deliberated clearance of forrest by cutting or burning

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8
Q

Deposition

A

The laying down of solid material such as silt on the river bed or floodplain

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9
Q

Drainage basin

A

The area of land drained by a river and its tributaries

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10
Q

Drainage basin hydrological cycle

A

An open system with inputs, outputs, transfers and stores that maps the movement of water through a drainage basin

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11
Q

Drilling

A

A form of abrasion where a pebble trapped trapped in a hollow on a stream bed is rotated by the moving water so that it wears away by the moving water so that it wears away the bedrock in a circular fashion

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12
Q

Efficiency

A

The ratio of the cross sectional area of a river and its wetted perimeter.It is expressed as the hydraulic radius

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13
Q

Erosion

A

The wearing away of the lands surface by rocks carried in a river

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14
Q

Evapotranspiration

A

The total amount of water leaving a vegetated surface by the joint process of evaporation and transpiration

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15
Q

Groundwater

A

Water which collects underground in pore spaces in rock

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16
Q

Groundwater flow

A

The movement of ground water, provides water for a river during drought

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17
Q

Hard engineering management strategies

A

A series of management strategies where there is controlled disruption of natural processes by using man made structures

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18
Q

Hjulstrom curve

A

A graph to show the relationship between the velocity of a river and the size of particles that can be eroded,transported and deposited

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19
Q

Hydraulic action

A

An erosion process where the banks and bed of the river are eroded by the moving water alone

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20
Q

Hydraulic radius

A

A measurement of the efficiency of a river; the ratio of the cross sectional area of a river and its wetted perimeter

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21
Q

Infiltration

A

The movement of water from its surface downwards into the soil

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22
Q

Interception

A

When precipitation is prevented from reaching the soil by leaves and branches(vegetation)

23
Q

Kinetic energy

A

The energy of a moving mass. Function of mass and velocity

24
Q

Overland flow

A

The rapid movement of water over saturated or impermeable land

25
Q

Percolation

A

The downward movement of water from soil to the rock below or within rock

26
Q

Potential energy

A

The energy stored in a mass as a result of its position in a force field ( gravity)

27
Q

Recurrence interval

A

The frequency with which a flood of given magnitude is likely to occur

28
Q

Rejuvenation

A

An increase in the energy of the river as a result of a fall in base level or uplift of land.

29
Q

Roughness

A

A measurement of the frictional drag on a river bed on the moving water.calculated using mannings N formula

30
Q

Runoff

A

All the water that flows out of a drainage basin

31
Q

Saltation

A

A form of transportation where river particles bounce along the river bed.

32
Q

Soft engineering management strategies

A

Ecologically sensitive management solutions to river erosion and flooding eg afforestation or land use zoning

33
Q

Solution

A

A form of erosion where the river water dissolves soluble bed rock

34
Q

Suspension

A

The transportation process whereby small material is carried in the body of the river

35
Q

Thalweg

A

The part of a river that has maximum velocity and depth

36
Q

Throughfall/stemflow

A

The water that drips off leaves or travels down the trunk of a tree during rainfall

37
Q

Throughflow

A

The water that moves down slope through soil

38
Q

Traction

A

The rolling of river bed load along a river channel

39
Q

Transportation

A

The movement of eroded particles from their origin to the place they are deposited

40
Q

Wetted perimeter

A

The total length of a river channel In cross section which is in contact with the water

41
Q

Confluence

A

Where two river or steams meet

42
Q

Types of water storage

A 
Interception,
Vegetation storage,
Surface storage,
Groundwater storage,
Channel storage
43
Q

What is the water balance

A

Shows the balance between the inputs and outputs

Affects how much water is stored in basin

44
Q

What is lag time

A

Delay between peak rainfall and peak discharge -takes time for water to flow into river.
Shorter lag time increases peak discharge

45
Q

River erosion methods

A 
Hydraulic action 
Abrasion (corrasion) 
Attrition 
Cavitation - air bubbles imploding that cause shockwaves to break off pieces of Rock of banks and beds 
Corrosion ( solution)
46
Q

Competence

A

Maximum particle size that a river is capable of carrying at a certain point

47
Q

Capacity

A

The total load that a river can transport at a given time

48
Q

What is helicoidal flow

A

Corkscrew like currents that spiral from bank to bank between pools (deepest water) causes more erosion and deepening of pools.
Also causes deposition in inside bend

49
Q

Physical factors that increase the risk of flooding

A
  • Sparse vegetation and deciduous trees- little interception
  • Impermeable ground - no infiltration
  • Circular drainage basins - all water arrive at same time as all points a similar distance away
  • High drainage density - drain quickly so short lag time, increase discharge
  • Steep slopes - water reach Channel faster , increase discharge
50
Q

Human factors that increase flood risk

A
  • Urbanisation - impermeable surfaces, gutters reduce lag time increase discharge
  • Deforestation - reduced interception
  • Flood management strategies eg if dams fail
  • Agriculture - over grazing , less interception, soil erosion
  • Climate change - increase rainfall
51
Q

Social impacts of flooding

A 
People and animals killed 
Floodwater contaminated - lack of clean drinking water
Contaminated water - diseases 
Possessions can be damaged 
People made homeless
52
Q

Economic impacts of flooding

A 
Businesses shut down 
Rescue work and repairs costly 
Unemployment levels rise 
Infrastructure destroyed 
Crops destroyed
53
Q

Environmental impacts of flooding

A

Floodwater contaminated so can pollute rivers
River banks eroded
Positive :
River sediment deposited so land more fertile
Wetlands can be created eg marshes, ponds and are habitats for many

AS Geography key words (9 decks)

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