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Physical Geography > R - Definitions > Flashcards

Flashcards in R - Definitions Deck (62)
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1
Q

Abrasion

A

The bed/banks are eroded by rocks/material carried by the river which scrape against, and wear away the channel.

2
Q

Antecedent Rainfall

A

Previous rainfall

3
Q

Attrition

A

Reduction in size of fragments/particles within a river due to erosion, and as fragments hit each other/the bed and banks, and wear down becoming small and smooth

4
Q

Braiding

A

If the river has a high sediment load, and low energy, the sediment is deposited, blocking the rivers route, this caused the river to continually change route.

5
Q

Baseflow

A

Water that reaches the channel largely through slow through flow, and from permeable rock below the water table

6
Q

Channel flow

A

The water that eventually flows out of the drainage basin

7
Q

Competance

A

The largest size particle a river can carry

8
Q

Condensation

A

The process by which water vapour is converted into water

9
Q

Corrosion/Solution

A

The minerals in the rock are dissolved by the water and carried away in solution, particularly carbonates

10
Q

Critical erosion velocity

A

The velocity needed to pick up (erode) particles of different sizes. In general the larger the particle, the higher the velocity needed to pick it up

11
Q

Delta

A

Areas of sediment deposited at the mouth of the river when it enters a slow-moving body water (eg the sea/a lake)

12
Q

Discharge

A

The volume of water flowing in a river per second (measured in cubic meters per second)

13
Q

Drainage basin

A

The land area or catchment area drained by a single river and its tributaries.

14
Q

Eustatic Rejuvination

A

Where the sea level rises or falls causing a GLOBAL change

15
Q

Evaportation

A

The process by which liquid water is transformed into water vapoure

16
Q

Evapotranspiration

A

The loss of warer from a drainage basin into the atmosphere from leaves of plants

17
Q

Flocculation

A

When clay and silt particles stick together

18
Q

Flood

A

A temporary excess of water which spills over onto land

19
Q

Floodplain

A

Flat areas of land either side of the river channel, made from deposited silts and clays

20
Q

Gradient

A

The slope of the land

21
Q

Graded profile

A

Long profile of a river where erosion and deposition are in equilibrium

22
Q

Groundwater flow

A

The slowest transfer of water in the drainage basin, through the underlying permeable rock strata

23
Q

Groundwater storage

A

The storage of water underground in permeable rock strata

24
Q

Helicoidal flow

A

The corkscrew flow inside a meander, responsible for moving material from the outside of one bend to the inside of the next

25
Q

Hydrological cycle

A

The continuous movement of water between the land, sea and air

26
Q

Hydraulic action

A

The sheer force of the moving water forces air into cracks and drags water over sediment, lifting it.
-most effective during times of high flow

27
Q

Hydraulic radius

A

The ratio of cross sectional area of the channel and the length of its wetter perimeter

28
Q

Impermeable

A

Not permitting the passage of fluid through the pores, interstices etc

29
Q

Infiltration

A

The downward movement of water into soil from the surface

30
Q

Interception

A

Prevention of precipitation from reaching the Earths surface by plants and trees

31
Q

Interception storage

A

The total volume of water held on the surface of vegetation

32
Q

Interlocking spurs

A

Outcrops of land which the river in the upper course must wind around as it hasn’t got the energy to erode through them. Usually accompanied by V Shaped valleys

33
Q

Isostatic change/rejuvination

A

Changes in sea level resulting from the rise and fall of land masses

34
Q

Lag time

A

The delay between peak rainfall and peak discharge

35
Q

Lateral erosion

A

Erosion of width

36
Q

Levées

A

Naturally occuring raised embankments formed when a river overflows its banks and material is deposited along the banks

37
Q

Long Valley Profile

A

The profile of a river from source to mouth

38
Q

Meander

A

Bends causing sinuosity within the river - typically found in the middle course

39
Q

Meander scar

A

Formed when an oxbow lake dries up

40
Q

Oxbow Lake

A

Horseshoe shaped lakes formed when a river erodes through the meander bend forming a new straight channel

41
Q

Overland flow

A

The movement of water over the surface of the land, usually when the ground is saturated or frozen or when precipitation is too intense for infiltration to occur

42
Q

Percolation

A

The gravity of water within soil

43
Q

Pools

A

Areas of deeper water with a more gentle flow, caused by difference in river energy

44
Q

Pothole

A

Holes within the riverbed carved into rock. Turbulent, high velocity water loaded with pebbles ‘drills’ into the rock. Pebbles become trapped in the rock

45
Q

Percipitation

A

Water in any form that falls from the atmosphere to the surface of the Earth.

46
Q

Rapids

A

If there is a sudden change in gradient, the river becomes more turbulent and has more erosive power

47
Q

Recurrence interval

A

The time period between floods of a particular level

48
Q

Rejuvination

A

When there is a fall in sea level relative to the land, or a rise in land relative to the sea, this gives the river more potential energy

49
Q

Relief

A

Shape of the land

50
Q

Riffles

A

Areas of shallower water with fast flow, caused by difference in river energy

51
Q

Sinuosity

A

The ‘curviness’ of the river

52
Q

Soil moisture

A

When precipitation is greater than evapotranspirtaion, any empty pores in the soil will be filled with water

53
Q

Soil storage

A

The total volume of water help within the soil

54
Q

Surface storage

A

Includes water in puddles, ponds and lakes

55
Q

Stem flow

A

The water that runs down the stems and branches of plants and trees during and after rain to reach the ground

56
Q

Thalweg

A

The line of greatest velocity or fastest flow with the river

57
Q

Surface Run off/Overground flow

A

The down slope flow of water over the surface

58
Q

Throughflow

A

Water moving slowly downhill through the soil

59
Q

Water table

A

The surface of the saturated layer of soil or rock

60
Q

Transpiration

A

The process by which water is lost into the atmosphere from a plant through stomata

61
Q

Watershed

A

The boundary of a drainage basin/the margin between 2 watersheds

62
Q

Wetted perimeter

A

Length of bed and banks that is in contact with the water