SOIL 2124 EXAM 4 QUESTIONS AND
ANSWERS 100% PASS 2026/2027
Mechanical/Engineering Measures - ANS 1. Riprap
2. Terracing
3. Bioenginerring
4. Sediment Traps
5. Retention Ponds
Riprap - ANS Large angular rocks may be laid at the bottom or the side of channels where
high water velocities may be expected
What kind of erosion counts for more than 40 percent of total soil loss in some watersheds -
ANS Steam-Bank Erosion
Terracing - ANS "Stairs-like" surface manipulation to reduce down-slope runoff velocity and
encourage retention of sediments
Not very common in the US
Bioengineering - ANS Use of vegetation to protect channels, reduce runoff velocity and trap
sediements
Sediment Traps - ANS Traps are designed to:
1. Slow down runoff
2026/2027 ALLRIGHTS RESERVED
1
,2. Trap sediments
Retention Ponds/Sedimentation Basins - ANS Ponds constructed down-slope of field which
collects runoff and allows sediments to settle prior to movement of surface water off-site
Wind Erosion in the US Key facts - ANS 1. Wind moves 40% of the soil transported by erosion
in the US
2. Problem in 75 million acres of land in the US
3. Up to 29 mg/ha of wind erosion-induced losses had been recorded in New Mexico
Three processes of wind erosion - ANS Detachment, Transportation, and Deposition
Factors affecting wind erosion - ANS 1. Wind velocity
2. Surface roughness
3. Soil properties
Wind Velocity - ANS Areas with steady, prevailing winds are very prone to wind erosion
Wind-carried sediments that strike the ground further increases the detachment process
Threshold Velocity - ANS 25 km/h at 12 inches above the ground
Soil Roughness - ANS Smooth soil surface devoid of vegetative cover- more susceptible to
wind erosion
The rougher the surface, the less severe the erosion is
Soil Properties - ANS Moisture content. Those areas with low annual rainfall are most
vulnerable
Stability of clods arrogates
Size of erodible fraction
2026/2027 ALLRIGHTS RESERVED
2
, Modes of wind-induced transportation - ANS 1. Saltation
2. Soil creep
3. Suspension
Saltation - ANS Movement of soil by a series of short bounces along the ground surfaces
May account for 50-90% of the soil movement
Intermediate sized particles- .05 to .5 mm diameter fine sand particles
Soil Creep - ANS Rolling and sliding along the surface of larger particles
May account for 5-25% of the total movement
Particles are 1.0 to .5 mm diameter
Moved by wind or salting particles
Suspention - ANS Dust particles of fine sand-size and smaller (less than .05 mm diameter) are
moved parallel to the ground surface and upward
Carries dust up to several miles upward to the atmosphere and hundreds of miles horizontally
May account for less than 15% of total movement
Remain suspended depending upon - ANS Incidence of rain or snow
Wind Velocity
Visability
Wind Erosion- Negative Impacts - ANS 1. Removes the most fertile portion of the soil
2. Obscures visibility and pollutes the air and water
3. Causes automobile accidents and fouls machinery
4. Imperils animal and human health
2026/2027 ALLRIGHTS RESERVED
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ANSWERS 100% PASS 2026/2027
Mechanical/Engineering Measures - ANS 1. Riprap
2. Terracing
3. Bioenginerring
4. Sediment Traps
5. Retention Ponds
Riprap - ANS Large angular rocks may be laid at the bottom or the side of channels where
high water velocities may be expected
What kind of erosion counts for more than 40 percent of total soil loss in some watersheds -
ANS Steam-Bank Erosion
Terracing - ANS "Stairs-like" surface manipulation to reduce down-slope runoff velocity and
encourage retention of sediments
Not very common in the US
Bioengineering - ANS Use of vegetation to protect channels, reduce runoff velocity and trap
sediements
Sediment Traps - ANS Traps are designed to:
1. Slow down runoff
2026/2027 ALLRIGHTS RESERVED
1
,2. Trap sediments
Retention Ponds/Sedimentation Basins - ANS Ponds constructed down-slope of field which
collects runoff and allows sediments to settle prior to movement of surface water off-site
Wind Erosion in the US Key facts - ANS 1. Wind moves 40% of the soil transported by erosion
in the US
2. Problem in 75 million acres of land in the US
3. Up to 29 mg/ha of wind erosion-induced losses had been recorded in New Mexico
Three processes of wind erosion - ANS Detachment, Transportation, and Deposition
Factors affecting wind erosion - ANS 1. Wind velocity
2. Surface roughness
3. Soil properties
Wind Velocity - ANS Areas with steady, prevailing winds are very prone to wind erosion
Wind-carried sediments that strike the ground further increases the detachment process
Threshold Velocity - ANS 25 km/h at 12 inches above the ground
Soil Roughness - ANS Smooth soil surface devoid of vegetative cover- more susceptible to
wind erosion
The rougher the surface, the less severe the erosion is
Soil Properties - ANS Moisture content. Those areas with low annual rainfall are most
vulnerable
Stability of clods arrogates
Size of erodible fraction
2026/2027 ALLRIGHTS RESERVED
2
, Modes of wind-induced transportation - ANS 1. Saltation
2. Soil creep
3. Suspension
Saltation - ANS Movement of soil by a series of short bounces along the ground surfaces
May account for 50-90% of the soil movement
Intermediate sized particles- .05 to .5 mm diameter fine sand particles
Soil Creep - ANS Rolling and sliding along the surface of larger particles
May account for 5-25% of the total movement
Particles are 1.0 to .5 mm diameter
Moved by wind or salting particles
Suspention - ANS Dust particles of fine sand-size and smaller (less than .05 mm diameter) are
moved parallel to the ground surface and upward
Carries dust up to several miles upward to the atmosphere and hundreds of miles horizontally
May account for less than 15% of total movement
Remain suspended depending upon - ANS Incidence of rain or snow
Wind Velocity
Visability
Wind Erosion- Negative Impacts - ANS 1. Removes the most fertile portion of the soil
2. Obscures visibility and pollutes the air and water
3. Causes automobile accidents and fouls machinery
4. Imperils animal and human health
2026/2027 ALLRIGHTS RESERVED
3
