VA DEQ SWM INSPECTOR ALL QUESTIONS AND
ANSWERS SURE A+
✔✔Soil Erosion - ✔✔the removal and transport of the land surface by erosive forces
such as water, wind, ice (freezing and thawing detaches soil), and gravity
soil particles from one location and deposit them on another location
important contributor to landscape formation by wearing away mountains, filling valleys,
creating sandbars, islands and coastal planes -- geological erosion (only makes up
about 30% of erosion)
erosion is a natural process, but in many places it is accelerated by human land
activities that disturb the soil
✔✔Five Stages of Soil Erosion - ✔✔1. raindrop impact
2. sheet erosion
3. rill erosion
4. gully erosion
5. channel erosion
✔✔Raindrop Impact - ✔✔the first effect of a rainstorm on the soil dislodging soil
particles and splashing then into the air; detached particles can be easily picked up by
water flowing over a site and become sheet erosion; most significant type of erosion;
the action of falling rain on disturbed or denuded soil is responsible for 90% or more of
total soil erosion
produces two damaging effects:
1. detachment of soil particles
2. sealing of the soil's surface
erosive capacity comes from the energy of its motion (kinetic energy)
, *magnitude of this energy is dependent on the amount and intensity of rainfall, raindrop
diameter, and raindrop velocity (larger raindrops strike soil even harder, spreading soil
particles further)
damaging effect of raindrops is the compacting, puddling, and sealing of the soil
surface; repeated strikes churn the surface into a slurry, which seals pore spaces int he
soil preventing water infiltration; as the continue to pound the land, raindrops will also
compact the bare soil, forming an almost complete seal; even on course sandy soil, this
action reduces the infiltration of water into the soil and leads to increased erosion and
runoff
✔✔Most erosive rains are concentrated during what months? - ✔✔May through
September
*this is also the period when land-disturbing (construction) is most active
✔✔Sheet Erosion - ✔✔second stage of erosion; soil's ability to infiltrate water is
exceeded and water starts to run across the surface of the soil (sheet flow); although
sheet erosion seldom detaches soil particles, the dislodges soil particles are transported
by sheet flow
✔✔Rill Erosion - ✔✔begins when shallow sheet flow begins to concentrate in low spots;
as flow changes from sheet flow to deeper flow in these low areas, the velocity and
turbulence increases; the energy of this concentrated flow detaches and transports soil
material, cutting tiny channels or rills that are only a few inches deep; at this stage, hand
tools or other surface treatments will easily repair erosion damage (topsoil)
✔✔Gully Erosion - ✔✔occurs when rills converge to form larger channels or gullies;
major difference between gully and rill erosion is size; gullies are too large to be
restored with conventional tillage equipment and usually require heavy
✔✔Channel Erosion - ✔✔can occur in two ways; typically you can observe vertical
sides and down-cutting of the receiving channel
1. when gullies are not repaired in time and large volumes of water increase the size of
the gully
2. in existing streams or drainage ways when the volume and velocity of flow destroys
the structural integrity of stream beds and banks
✔✔Four Factors Influencing Erosion - ✔✔1. climate
2. ground cover
3. soil properties
4. topography
ANSWERS SURE A+
✔✔Soil Erosion - ✔✔the removal and transport of the land surface by erosive forces
such as water, wind, ice (freezing and thawing detaches soil), and gravity
soil particles from one location and deposit them on another location
important contributor to landscape formation by wearing away mountains, filling valleys,
creating sandbars, islands and coastal planes -- geological erosion (only makes up
about 30% of erosion)
erosion is a natural process, but in many places it is accelerated by human land
activities that disturb the soil
✔✔Five Stages of Soil Erosion - ✔✔1. raindrop impact
2. sheet erosion
3. rill erosion
4. gully erosion
5. channel erosion
✔✔Raindrop Impact - ✔✔the first effect of a rainstorm on the soil dislodging soil
particles and splashing then into the air; detached particles can be easily picked up by
water flowing over a site and become sheet erosion; most significant type of erosion;
the action of falling rain on disturbed or denuded soil is responsible for 90% or more of
total soil erosion
produces two damaging effects:
1. detachment of soil particles
2. sealing of the soil's surface
erosive capacity comes from the energy of its motion (kinetic energy)
, *magnitude of this energy is dependent on the amount and intensity of rainfall, raindrop
diameter, and raindrop velocity (larger raindrops strike soil even harder, spreading soil
particles further)
damaging effect of raindrops is the compacting, puddling, and sealing of the soil
surface; repeated strikes churn the surface into a slurry, which seals pore spaces int he
soil preventing water infiltration; as the continue to pound the land, raindrops will also
compact the bare soil, forming an almost complete seal; even on course sandy soil, this
action reduces the infiltration of water into the soil and leads to increased erosion and
runoff
✔✔Most erosive rains are concentrated during what months? - ✔✔May through
September
*this is also the period when land-disturbing (construction) is most active
✔✔Sheet Erosion - ✔✔second stage of erosion; soil's ability to infiltrate water is
exceeded and water starts to run across the surface of the soil (sheet flow); although
sheet erosion seldom detaches soil particles, the dislodges soil particles are transported
by sheet flow
✔✔Rill Erosion - ✔✔begins when shallow sheet flow begins to concentrate in low spots;
as flow changes from sheet flow to deeper flow in these low areas, the velocity and
turbulence increases; the energy of this concentrated flow detaches and transports soil
material, cutting tiny channels or rills that are only a few inches deep; at this stage, hand
tools or other surface treatments will easily repair erosion damage (topsoil)
✔✔Gully Erosion - ✔✔occurs when rills converge to form larger channels or gullies;
major difference between gully and rill erosion is size; gullies are too large to be
restored with conventional tillage equipment and usually require heavy
✔✔Channel Erosion - ✔✔can occur in two ways; typically you can observe vertical
sides and down-cutting of the receiving channel
1. when gullies are not repaired in time and large volumes of water increase the size of
the gully
2. in existing streams or drainage ways when the volume and velocity of flow destroys
the structural integrity of stream beds and banks
✔✔Four Factors Influencing Erosion - ✔✔1. climate
2. ground cover
3. soil properties
4. topography
