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Soil erosion > Final exam > Flashcards

Final exam Flashcards

1
Q

What is rills?

A

channels so small that they can be obliterated by normal tillage operations

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2
Q

Topography

A

Refers to the geometry of the land scape

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3
Q

Ephemeral gull erosion

A

Occur within field sized areas where land-disturbing operations take place.

The microtopography of the surface cause erosion to form again in the same location

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4
Q

why does vegetation reduce erosion

A

Vegetation has the potential to protect the surface against water (raindrop impact and run-off) and wind pressures, and allowing any excess surface water to infiltrate the soil

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5
Q

What to think about when u try to prevent erosion?

A 
KE of raindrops
Support infiltration
increase retention capacity
decrease surface runoff velocity
improve soil structure and porosity
improve biological activity (structure, porosity)
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6
Q

How to protect against wind erosion?

A

Increase surface roughness
reduce wind speed(velocity)
reduce mechanical damage of plants

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7
Q
  1. Erosion Control BMP

2. Sediment Control BMP

A
  1. = stop soil moving from original location

2. = trap soil that‘s already moved

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8
Q

Reasons to measure erosion

A

Erosion measurement (EM) and estimates provide the basis for:

  • Government policies and programs
  • Allocation of government resources
  • Regulation of environmental
    impact resulting from human activities

-conservation planning

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9
Q

Characteristics influencing erosion and sedimentation

A
  1. Weather and climate
  2. Soil properties
  3. Topography (+ surface roughness)
  4. Vegetation (canopy, ground cover, plant types, production levels)
  5. Land management (+types and intensity of land-disturbing activities)
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10
Q

Which are the types of Measurements scales?

A
  1. Temporal
    - From tainstorm/winddstorm to several years
    - Storms of various return period (N-yers)
  2. Spatial
    - Range from interrill/rill sediment source from hillslope to sediment discharege from catchments

-From small plots to entire regions

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11
Q

Technique choice depends on:

A
  1. Erosion process to be measured
  2. Temporal and spatial scale
  3. Uses of collected data
  4. Available time, personnel, financial resources
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12
Q

The Measurement plan – three steps:

A
  1. Selecting M site (where)
  2. M frequency and duration (when)
  3. M techniques for erosion processeses and envi conditions (how)
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13
Q

Evaluating E-control practices =

A

Preformance X Costs + ease of installation + maintanance

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14
Q

How to measure wind erosion

A

Measure of INFLOW vs OUTFLOW
(Increase = wind erosion)
(Decrease = Deposition)
Numerous M sites to collect all of sediment

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15
Q

Scientific erosion research

A
  • Conducted to improve our understanding of erosion
  • Needs carefully constructed research design
  • Field measurements
  • Laboratory measurements
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16
Q

What does USLE stand for?

A

Universal soil loss equation.

usle predicts long-term average annual rate of erosion

17
Q

A = RKLSC*P

A

A= potential long-term average annual soil loss in
tones per hectare per year

R= rainfall pattern(rainfall-runoff erosion factor.
K=soil type(Soil erodibility factor)
L=Slope length factor
S= Slope steepness factor
(L+S= topography)
C = Crop system (cover management factor)
P=Management practices (is a supporting practices factor)

18
Q

4 ways to measure erosion

A

1 Change in weight

  1. Change in surface elevation
  2. Change in channel cross-section dimensions
  3. Sediment collection from Erosion plots and catchment.
19
Q

On what principle is the measurement “change in weight” based on, And when is it used?

A

Erosion M by a change in wait is based on the principle that erosion removes material from the source area.

Technique is generally used in lab or field with small soil samples.

20
Q

On what principle is the measurement “change in surface elevation” based on, And what M techniques is used?

A

It is based on the principle that erosion and deposition by water or wind change the elevation of the land surface.

  • Erosion stakes and pins
  • Erosion bridges and frames
  • Photogrametic methods
  • Laser scanning of topography
21
Q

Where is the measurement “change in cross-sectional dimensions” used?

A

Rills and other small channels. –> small areas are measured whit a rill profile or micro-roughness meter.

Bigger channels –> Generally survey equipment. Permanent bench marks are implemented on either side of the channel.

22
Q

What can u measure with Sediment collection from Erosion plots and catchment?

A
  1. Soil detachment by raindrop impact
  2. Interrill erosion
  3. Rill erosion
  4. Total erosion
  5. Sediment yield

Soil erosion (3 decks)

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