Lecture 1

Question 1

What is detachment?

Answer 1

separation of soil particle from soil mass.

Question 2

What is entrainment?

Answer 2

Transport of detach particles from the soil surface to a fluid flow. (wind, water, ice).

Question 3

Transport

Answer 3

Transportation of sediment

Question 4

Disposition

Answer 4

transfer of sediment from the sediment lobe to the soil surface.

Question 5

Definition of shear stress

Answer 5

Shear stress is when the direction of stress/force is parallel to the affected surface as opposed to perpendicular

Question 6

Small impoundments

Answer 6

Reduce sediment movement from landscape.
Occurs naturally and constructed.
Almost no transport capacity

Question 7

What can reduce the erosivity of wind?

Answer 7

Vegetation cover, surface roughness reduce erosivity

Question 8

Three modes of wind transportation

Answer 8

1 creep
2 Saltation
3 suspension

Question 9

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Answer 9

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Question 10

Infiltration capacity

Answer 10

Soils capacity to hold water

Question 11

Material strength

Answer 11

resistance to stress

Question 12

Types of erosion differentiated on the basis of:

Answer 12

• Location (hillslope, channel erosion)

* Agent (water, wind(deflation), ice(glacier erosion is called denudation)

Question 13

What cases soil aggregation?

Answer 13

Attractive forces among soil particles, (some particles binds stronger than other, the space between aggregate creates pore space for air or water)

Question 14

Soil permeability

Answer 14

Is a measure indicating the capacity of the soil to allow fluids to pass through it.

Question 15

Erosivity

Answer 15

Erosivity is the term used to describe the potential of raindrop impact, runoff from snowmelt, or water applied with an irrigation system rainstorm to detach and erode soil.

Question 16

Temporal and spatial variability

Answer 16

Wetting, drying, freezing, thawing, addition of organic matter

Question 17

Primary factors that influences soil erosin

Answer 17

1 Climate
2 Topography
3 Land use and landcover

Question 18

Erodibility

Answer 18

The susceptibility of the ground(soil) surface to erosion.

Question 19

Erosivity isn’t always directly related to rainfall amount, aspects to consider

Answer 19

• Spatial variation

- Temporal variation

Question 20

water erosion consist of 3 processes

Answer 20

1 detachment
2 transport
3 deposition

Question 21

How to classify soil erosion?

Answer 21

You can classify by agent causing erosion –> water, wind

Question 22

Wind abrasion

Answer 22

the impact of particles carried by the wind. The wind picks up particles and moves them. When the particles collide with a solid object, the impact causes small pieces of the object to break off.

Question 23

The three processes of wind erosion

Answer 23

creep,
saltation
suspension.

Question 24

Mechanical movement of soil

Answer 24

Tillage – Tillage lift soil layer, gravity cases downslope movement.
Mass movement – rainfall saturates (mättar) the upper soil layer and reduce soil strength.

Question 25

Deposition occurs when and where…

Answer 25

the sediment load si greater than the wind’s capacity

Question 26

Interill + rill areas = overland flow areas of landscape, caused by:

Answer 26

Hortonian flow/Horton overland flow which is infiltration capacity + depression storage capacity.

Question 27

Open channels

Answer 27

An open channel has free-water surface exposed to atmospheric pressure. Open channels occurs in in rills, streams and gully’s.

Question 28

Pipe flow

Answer 28

Pipe flow fills the conduit with water that flows under the hydraulic pressure. (water frequently flows through the soil just below the surface. The soil may contain macropores, other small openings and channels left by for example decaying roots, burrowing insects and animals. These internal open spaces in the soil may become pipes, and pipe flow can erode flow, causing a type of erosion know as piping.

Question 29

Sheet erosion

Answer 29

Sheet erosion occurs as a shallow ‘sheet’ of water flowing over the ground surface, which is a uniform to remove removal of soil from surface, is assumed to be the first phase of the erosion process.

Question 30

Catchment sediment yield

Answer 30

= the amount of sediment delivered at the outlet of the catchment

Question 31

irrigation

Answer 31

Irrigation water is applied to the land by overhead by sprinklers or small pipes, surface applied flow.

Question 32

Does all drops move sediment?

Answer 32

No if it’s already water on the ground that’s 3 times deeper than the size of the drop there is no impact.

Question 33

Small impoundments (reservoirs)

Answer 33

Reduce sediment movement from landscape
Natural and constructed
Almost no sediment transport