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Flashcards in Rivers Key Terms Deck (76)
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31

Infiltration rate

The rate of water absorption expressed in millimetres per minute

32

Interception

Process by which incoming precipitation is trapped by vegetation and buildings. Water is then transferred to the earth's surface or evaporated.

33

Interlocking Spurs

Protrusions of higher land characteristic of the upper sections of a river valley resulting from the river's winding course and more resistant rocks.

34

Isovel

A lining joining pointed of equal velocity in a river channel.

35

Knick point

A break of slope in the long profile of river due to rejuvenation. Because of the renewed down cutting a new long profile is created and where this intersects the former long profile a Knick point is created.

36

Lag time

The time between peak precipitation and peak discharge

37

Laminar flow

Horizontal movement of water

38

Levee

A bank of sediment along the edge of a river channel, deposited naturally with floodwaters. Often raised and strengthened artificially to contain floodwaters.

39

Load

Pebbles, particles and dissolved matter carried by a river

40

Long profile

A river course from its source in an upland area along its channel to its mouth.

41

Meander

A bend in a river with a sinuosity ratio of more than 1:5

42

Natural levee

An embankment on the sides of a river formed by the deposition of silt during flooding

43

Overland flow / surface run off

Process by which water moves downslope over the earth's surface in unconfined channels under the influence of gravity. Saturated overland flow occurs when excess water flows across the ground surface due to subsurface being saturated.

44

Percolation

Process by which water moves vertically downwards through soil and rock

45

Permeability

Ability of rocks, soil or sediment to permit water to flow through it. Permeable rocks allow water to pass through them via bedding planes and joints e.g. Limestone. Impermeable rocks like granite produce more run off and streams.

46

Point bar

Sediment deposited under water on the inside bed of a meander

47

Pools and riffles

The alternating pattern of deep pools and is reaches where a river flows across gravel bars. Distribution if regularly spaced with the distance between pools being 5-7 times greater than the channel width.

48

Porous rocks

Allow water to pass through them via pores e.g. Sandstone and chalk

49

Recessional limb

Part of the hydrograph showing the speed at which the discharge declines after a peak back to its pre storm level

50

Precipitation

Process by which water is transferred from the atmosphere to surface in the form of snow, sleet, hail, rain, fog. Input into drainage system.

51

Recharge

Water added to groundwater or soil to replace that lost by evaporation or transpiration

52

River regime

Variation in discharge from January to December

53

Rejuvenation

The state of a river when it's energy has been revitalised leading to an increase in erosional capability. Results from a fall in base level, due to fall in sea level or uplift of land.

54

Rising limb

The part of a flood hydrograph which shows how quickly floodwaters rise due to storm event

55

River cliff / Bluff

Erosional landform on the outside bend of a meander

56

Saltation

Bed load is transported by bounding motion of lighter particles

57

Sinuosity

The curving nature of the meander. The actual channel length divided by the straight line distance.

58

Soil moisture budget

The balance between moisture inputs and outputs in a soil over time.

59

Soil moisture deficit

A shortage of soil moisture. Evapotranspiration > precipitation- in summer

60

Soil moisture recharge

A period after summer or drought when lost moisture has to be replaced