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Physical Geography > R - Definitions > Flashcards

Flashcards in R - Definitions Deck (62):
1

Abrasion

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

2

Antecedent Rainfall

Previous rainfall

3

Attrition

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

Braiding

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

Baseflow

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

6

Channel flow

The water that eventually flows out of the drainage basin

7

Competance

The largest size particle a river can carry

8

Condensation

The process by which water vapour is converted into water

9

Corrosion/Solution

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

10

Critical erosion velocity

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

Delta

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

12

Discharge

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

13

Drainage basin

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

14

Eustatic Rejuvination

Where the sea level rises or falls causing a GLOBAL change

15

Evaportation

The process by which liquid water is transformed into water vapoure

16

Evapotranspiration

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

17

Flocculation

When clay and silt particles stick together

18

Flood

A temporary excess of water which spills over onto land

19

Floodplain

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

20

Gradient

The slope of the land

21

Graded profile

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

22

Groundwater flow

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

23

Groundwater storage

The storage of water underground in permeable rock strata

24

Helicoidal flow

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

25

Hydrological cycle

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

26

Hydraulic action

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

Hydraulic radius

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

28

Impermeable

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

29

Infiltration

The downward movement of water into soil from the surface

30

Interception

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

31

Interception storage

The total volume of water held on the surface of vegetation

32

Interlocking spurs

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

Isostatic change/rejuvination

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

34

Lag time

The delay between peak rainfall and peak discharge

35

Lateral erosion

Erosion of width

36

Levées

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

37

Long Valley Profile

The profile of a river from source to mouth

38

Meander

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

39

Meander scar

Formed when an oxbow lake dries up

40

Oxbow Lake

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

41

Overland flow

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

Percolation

The gravity of water within soil

43

Pools

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

44

Pothole

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

Percipitation

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

46

Rapids

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

47

Recurrence interval

The time period between floods of a particular level

48

Rejuvination

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

Relief

Shape of the land

50

Riffles

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

51

Sinuosity

The 'curviness' of the river

52

Soil moisture

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

53

Soil storage

The total volume of water help within the soil

54

Surface storage

Includes water in puddles, ponds and lakes

55

Stem flow

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

56

Thalweg

The line of greatest velocity or fastest flow with the river

57

Surface Run off/Overground flow

The down slope flow of water over the surface

58

Throughflow

Water moving slowly downhill through the soil

59

Water table

The surface of the saturated layer of soil or rock

60

Transpiration

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

61

Watershed

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

62

Wetted perimeter

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