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HDSO Dynamic Planet Fresh Water > Chapter 6 Soil water > Flashcards

Chapter 6 Soil water Flashcards

1
Q

When dry soil is crushed in the hand, it can be seen that it is composed of

A

all kinds of particles of different sizes.

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2
Q

When dry soil is crushed in the hand, it can be seen that it is composed of all kinds of particles of different sizes.

Most of these particles originate from

A

degradation of rocks; they are called mineral particles.

Some originate from residues of plants or animals (rotting leaves, pieces of bone, etc.), these are called organic particles (or organic matter).

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3
Q

The soil particles seem to touch each other, but in reality have

A

spaces in between.

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4
Q

The soil particles seem to touch each other, but in reality have spaces in between. These spaces are called

A

pores

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5
Q

When the soil is “dry”, the pores are mainly filled with

A

air

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6
Q

After……………………………………….., the pores are mainly filled with water

A

irrigation or rainfall

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7
Q

Living material is found in the soil. It can be …………………………………………………………..

A

live roots as well as beetles, worms, larvae etc.

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8
Q

living materials help to…………………….. and thus……………………………………………..

A

aerate the soil and thus create favourable growing conditions for the plant roots

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9
Q

The following image represents

A

The composition of the soil

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10
Q

A represents

A

Soil Particles

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11
Q

B represents

A

water

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12
Q

C represents

A

air

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13
Q

D represents

A

root

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14
Q

If a pit is dug in the soil,………………………………………………………………………….. can be seen.

A
  1. At least 1 m deep,
  2. Various layers,
  3. Different in colour and composition
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15
Q

If a pit is dug in the soil, at least 1 m deep, various layers, different in colour and composition can be seen. These layers are called

A

horizons

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16
Q

the profile of the soil:

A

succession of horizons

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17
Q

soil profile:

A
  1. The plough layer
  2. The deep plough layer
  3. The subsoil layer
  4. The parent rock layer
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18
Q

The following image represent the

A

Soil profile

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19
Q

A represent

A

Plough layer

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20
Q

B represents

A

Deep plough layer

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21
Q

C represents

A

Subsoil layer

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22
Q

D represents

A

The parent rock layer

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23
Q

Name of the particles:

gravel

Size limits in mm:

A

larger than 1

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24
Q

Name of the particles

gravel

distinguishable with the naked eye:

A

Obviously

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25
Q

Name of the particles:

sand

size limit in mm:

A

1 to 0.5

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26
Q

Name of the particles:

sand

Distinguishable with naked eye:

A

easily

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27
Q

Name of the particles:

silt

Size limits in mm:

A

0.5 to 0.002

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28
Q

Name of the particles:

silt

Distinguishable with naked eye

A

barely

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29
Q

Name of the particles:

clay

Size limits in mm:

A

less than 0.002

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30
Q

Name of the particles:

clay

Distinguishable with the naked eye:

A

impossible

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31
Q

………………………………..determines the soil texture.

A

The amount of sand,

silt and

clay present in the soil

32
Q

In ……………………….textured soils: ………………………… is predominant (sandy soils).

A

coarse

sand

33
Q

In ……………………. textured soils: ……………….is predominant (loamy soils).

A

medium

silt

34
Q

In …………………..textured soils: …………………..is predominant (clayey soils).

A

fine

clay

35
Q

In the field, soil texture can be determined by

A

rubbing the soil between the fingers

36
Q

Soil structure refers to

or soil structure refers to

A

the grouping of soil particles (sand, silt, clay, organic matter and fertilizers) into porous compounds. These are called aggregates

or

Soil structure also refers to the arrangement of these aggregates separated by pores and cracks

37
Q

When present in the topsoil, a massive structure

A

blocks the entrance of water

38
Q

When present in the topsoil, a massive structure blocks the entrance of water; seed germination is difficult due to

A

poor aeration

39
Q

if the topsoil is ………………………………., the water enters easily and the seed germination is better

A

granular

40
Q

The following soil structure is

A

Grangular

41
Q

The following soil structure is

A

Blocky

42
Q

The following soil structure is

A

Prismatic

43
Q

The following soil structure is

A

Massive

44
Q

In Granular soil structure the flow is ……………………..

A

rapid

45
Q

In Blocky soil structure the flow is ……………………..

A

moderate

46
Q

In Prismatic soil structure the flow is ……………………..

A

moderate

47
Q

In Massive soil structure the flow is ……………………..

A

Slow

48
Q

The depth of the ……………………………………varies greatly from place to place, mainly due to changes in ………………………………..

A

groundwater table

topography of the area

49
Q

In one particular place or field, the depth of the groundwater table may vary in …………

A

time

50
Q

A perched groundwater layer can be found

A

on top of an impermeable layer rather close to the surface (20 to 100 cm)

51
Q

A perched groundwater layer can be found on top of an impermeable layer rather close to the surface (20 to 100 cm). It covers usually a …………………..area.

A

limited

52
Q

The top of the perched water layer is called the

A

perched groundwater table

53
Q

A represents

A

Soil surface

54
Q

B represents

A

Perched water layer

55
Q

C represents

A

Compacted layer

56
Q

D represents

A

ground water table

57
Q

Infiltration:

A

The movement of water from the soil surface into the soil

58
Q

Redistribution:

A

The subsequent movement of infiltrated water in the unsaturated zone of a soil.

59
Q

Redistribution involve:

A
  1. Exfiltration
  2. Capillary rise
  3. Recharge
  4. Interflow
60
Q

exfiltration

A

evaporation from the upper layer of the soil

61
Q

capillary rise

A

movement upward from the saturated zone to the unsaturated zone due to surface tension

62
Q

recharge

A

movement of water from the unsaturated zone to the saturated zone

63
Q

interflow

A

flow that moves downslope

64
Q

Infiltration and redistribution depend critically on……………………………………………….

A

the material and hydraulic properties of soils

65
Q

The groundwater can be sucked …………………………by the soil through …………………………….. that are called …………………………

A

upward

very small pores that are called capillars .

66
Q

The groundwater can be sucked upward by the soil through very small pores that are called capillars. This process is called ……………………..

A

capillary rise

67
Q

Soil texture:
Coarse (sans)

Capillary rise (in cm):

A

20 to 50 cm

68
Q

Soil texture:
medium

Capillary rise(in cm):

A

50 to 80 cm

69
Q

Soil texture:
fine (clay)

Capillary rise (in cm):

A

more than 80 cm up to several meters

70
Q

Darcy’s Law states that the flow rate in the horizontal depends on

A

(1) the ability of the soil to “conduct” water;
(2) the magnitude and direction of the slope, which is the gravitational potential energy gradient per unit weight of flowing water (soil water wants to flow downhill, towards lower gravitational potential energy), and
(3) the magnitude and direction of the horizontal gradient in soil water pressure (if soil water pressure decreases in the x direction, the water wants to flow in that direction).

71
Q

hydraulic conductivity

A

the vertical flow rate depends on the sum of the gravitational potential energy gradient per unit weight of water (dz/dz =1) and the vertical gradient in soil water pressure.

72
Q

In a steady state (qz equals ……………)

A

zero

73
Q

there is a balance between …………………………… and ………………………………

A

the effect of gravity

an upward decrease in soil water pressure

74
Q

the effect of gravity (which always wants to …………………………………of ………………………………, .towards……………)

A

pull the water “down the gradient”

gravitational potential energy

lower z

75
Q

an upward decrease in soil water pressure (“…………….. the gradient” is in the …………………….. z direction).

A

down

positive

76
Q

if the effect of gravity and an upward decrease in soil water pressure don’t balance there is

A

a vertical water flow (up or down, depending on which term “wins”), the magnitude of which depends of the size of the imbalance and the value of the hydraulic conductivity coefficient.

77
Q
A

HDSO Dynamic Planet Fresh Water (8 decks)

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