VA DEQ SWM INSPECTOR UPDATED EVALUATION
EXAM QUESTIONS AND ANSWERS SURE A+
✔✔Gully Erosion - ✔✔4th stage of soil erosion, occurs when rills converge to form
larger channels or gullies, major difference is size as gullies are too large to be restored
with tillage equipment
✔✔Channel Erosion - ✔✔5th stage of erosion, occurs when gullies are not repaired in
time, in existing streams, the volume/velocity of flow destroys the structural integrity of
banks
✔✔Factors influencing Erosion - ✔✔1. Climate
2. Groundcover
3. Soil Properties
4. Topography
✔✔Raindrops are responsible for ___% of the erosion that occurs on disturbed soil. -
✔✔90%
✔✔Use of any surface cover material, e.g., vegetation, mulch, matting, can reduce soil
erosion by ___ - ___% - ✔✔90-99%
✔✔Key Soil Properties include - ✔✔Soil Structure, Soil texture, bulk density, percentage
of organic matter, infiltration rate, permeability rate
✔✔Susceptibility of a particular soil to erosion is called its erodibility factor or ___ factor
- ✔✔K factor
✔✔Soil properties used to develop the K factor - ✔✔Permeability, Soil texture, Soil
structure, organic matter content; higher K value = more susceptible to soil erosion
✔✔K Factor, low erodibility range - ✔✔0.23 or lower
, ✔✔K Factor, moderate erodibility range - ✔✔0.24 - 0.36
✔✔K Factor, high erodibility range - ✔✔0.37 or higher
✔✔Slope gradient percentage range = low erosion hazard - ✔✔0-7%
✔✔Slope gradient percentage range = moderate erosion hazard - ✔✔7-15%
✔✔Slope gradient percentage range = high erosion hazard - ✔✔15% and over
✔✔Soil classification system consisting of 4 hydrologic soil groups (HSGs) (A, B, C, or
D) developed by NRCS. Soils are classified based on what factor? - ✔✔Minimum
infiltration rate
✔✔Group A Soils - ✔✔Low runoff potential; high infiltration rate even when thoroughly
wetted; consist of excessively drained sands and gravels; high water transmission rates
(.30"/hr or greater); includes sand, loamy sand, sandy loam
✔✔Group B Soils - ✔✔Moderately low runoff potential; moderately well to well-drained
soils; moderate water transmission rates (0.15-0.30"/hr); includes silt loam and loam
✔✔Group C Soils - ✔✔Moderately high runoff potential; typically have layer near the
surface that impedes the downward movement of water or soils; low water transmission
rates (0.05-0.15"/hr); include sandy clay loam
✔✔Group D Soils - ✔✔High runoff potential; consist primarily of clays with high swelling
potential, soils with permanently high water tables; very low water transmission rates (0-
0.05"/hr); include clay loam, silty clay loam, sandy clay, silty clay, or clay
✔✔4 Topographic features influencing site erodibility - ✔✔slope grade, length, shape,
and orientation
✔✔Slope gradient associated with a LOW erosion hazard - ✔✔0-7%
✔✔Slope gradient associated with a MODERATE erosion hazard - ✔✔7-15%
✔✔Slope gradient associated with a HIGH erosion hazard - ✔✔15% and over
✔✔Slope length where 0-7% slope gradient becomes CRITICAL - ✔✔300ft
✔✔Slope length where 7-15% slope gradient becomes CRITICAL - ✔✔150ft
✔✔Slope length where 15-25% slope gradient becomes CRITICAL - ✔✔75ft
EXAM QUESTIONS AND ANSWERS SURE A+
✔✔Gully Erosion - ✔✔4th stage of soil erosion, occurs when rills converge to form
larger channels or gullies, major difference is size as gullies are too large to be restored
with tillage equipment
✔✔Channel Erosion - ✔✔5th stage of erosion, occurs when gullies are not repaired in
time, in existing streams, the volume/velocity of flow destroys the structural integrity of
banks
✔✔Factors influencing Erosion - ✔✔1. Climate
2. Groundcover
3. Soil Properties
4. Topography
✔✔Raindrops are responsible for ___% of the erosion that occurs on disturbed soil. -
✔✔90%
✔✔Use of any surface cover material, e.g., vegetation, mulch, matting, can reduce soil
erosion by ___ - ___% - ✔✔90-99%
✔✔Key Soil Properties include - ✔✔Soil Structure, Soil texture, bulk density, percentage
of organic matter, infiltration rate, permeability rate
✔✔Susceptibility of a particular soil to erosion is called its erodibility factor or ___ factor
- ✔✔K factor
✔✔Soil properties used to develop the K factor - ✔✔Permeability, Soil texture, Soil
structure, organic matter content; higher K value = more susceptible to soil erosion
✔✔K Factor, low erodibility range - ✔✔0.23 or lower
, ✔✔K Factor, moderate erodibility range - ✔✔0.24 - 0.36
✔✔K Factor, high erodibility range - ✔✔0.37 or higher
✔✔Slope gradient percentage range = low erosion hazard - ✔✔0-7%
✔✔Slope gradient percentage range = moderate erosion hazard - ✔✔7-15%
✔✔Slope gradient percentage range = high erosion hazard - ✔✔15% and over
✔✔Soil classification system consisting of 4 hydrologic soil groups (HSGs) (A, B, C, or
D) developed by NRCS. Soils are classified based on what factor? - ✔✔Minimum
infiltration rate
✔✔Group A Soils - ✔✔Low runoff potential; high infiltration rate even when thoroughly
wetted; consist of excessively drained sands and gravels; high water transmission rates
(.30"/hr or greater); includes sand, loamy sand, sandy loam
✔✔Group B Soils - ✔✔Moderately low runoff potential; moderately well to well-drained
soils; moderate water transmission rates (0.15-0.30"/hr); includes silt loam and loam
✔✔Group C Soils - ✔✔Moderately high runoff potential; typically have layer near the
surface that impedes the downward movement of water or soils; low water transmission
rates (0.05-0.15"/hr); include sandy clay loam
✔✔Group D Soils - ✔✔High runoff potential; consist primarily of clays with high swelling
potential, soils with permanently high water tables; very low water transmission rates (0-
0.05"/hr); include clay loam, silty clay loam, sandy clay, silty clay, or clay
✔✔4 Topographic features influencing site erodibility - ✔✔slope grade, length, shape,
and orientation
✔✔Slope gradient associated with a LOW erosion hazard - ✔✔0-7%
✔✔Slope gradient associated with a MODERATE erosion hazard - ✔✔7-15%
✔✔Slope gradient associated with a HIGH erosion hazard - ✔✔15% and over
✔✔Slope length where 0-7% slope gradient becomes CRITICAL - ✔✔300ft
✔✔Slope length where 7-15% slope gradient becomes CRITICAL - ✔✔150ft
✔✔Slope length where 15-25% slope gradient becomes CRITICAL - ✔✔75ft
