EROSION, SEDIMENT TRANSPORT
PROCESSES AND IMPACTS FINAL EXAM
QUESTIONS AND 100% VERIFIED
ANSWERS!!
How do soil properties influence soil erodibility?
Both classes of properties are influenced by the nature of the soil and the management or
treatment it undergoes.
What concept did Middleton (1930) consider in relation to soil erodibility?
Middleton considered the dispersion ratio (%), which is the ratio of the weight.
What is the erosion ratio defined as?
The dispersion ratio divided by the ratio of colloid to moisture equivalent.
What indices of soil erodibility (K) were suggested by Bhatia and Srivastaria (1954)?
Dispersion ratio, clay ratio, silt to clay ratio, and soil aggregation.
According to Wang and Lin (1970), what are the principal determinants of soil erodibility
for arable soils?
Aggregate stability and clay content.
What five soil properties did Young and Mutchler (1977) find explained 90% of the
variations in erodibility of Minnesota soils?
Particle size distribution, bulk density, aggregate index, dispersion ratio, and the amount of
montmorillonite.
What relationship did Marquez (1980) find regarding soil erodibility (K) and water stable
aggregates?
K is inversely proportional to water stable aggregates, hydraulic conductivity, bulk density, and
carbon to nitrogen ratio.
,What did Wischmeier and Mannering (1969) conclude about soil erodibility (K)?
K is a complex interaction of soil physical and chemical properties.
List some factors that influence soil erodibility according to Wischmeier and Mannering
(1969).
Particle size distribution, organic matter content, pH, structure, bulk density, steepness and slope
shape, pore space filled by air, aggregation, residual effects of vegetation, and chemistry of
parent material.
What type of soil is considered the most erodible?
Soils that are high in silt, low in clay, and low in organic matter content.
How does the silt fraction affect soil erodibility?
A soil usually becomes less erodible with a decrease in its silt fraction, regardless of whether
sand or clay increases.
What is the effect of organic matter (OM) on soil?
OM improves soil aggregation and the infiltration capacity of soils.
What does the formula for soil erodibility (K) include according to Wischmeier and
Mannering (1969)?
K = OM + S + C, where OM is organic matter content, S is % sand, and C is the clay ratio.
What is the relationship between slope and erosion processes?
Increasing slope generally increases the rates of erosion processes.
What happens to runoff flow regimes as slope length increases?
Runoff flow regimes change, leading to a bigger build-up of surface runoff or deeper runoff
depth.
What is the consensus among researchers regarding the effect of slope on soil loss?
E is proportional to S raised to an exponent b, but there is no consensus on the value of b.
, What equation did Smith and Whitt propose for claypan soils?
Re = 0.1 + 0.21S^(4/3), where Re is the relative soil loss to unity loss from a 3% slope.
What is the significance of the bulk of available data regarding slope and soil loss?
The data is not in agreement on the effect of slope on soil loss.
What does the term 'relative soil loss' refer to in the context of slope?
It refers to the comparison of soil loss from different slopes, often expressed in relation to a
standard slope.
How does increasing slope length affect detachment by runoff?
Detachment by runoff increases with increasing slope length as the hydraulic radius increases.
What is the role of aggregation in soil erodibility?
Aggregation improves soil structure and reduces erodibility.
What are the implications of soil erodibility for agricultural practices?
Understanding soil erodibility helps in managing soil conservation and preventing erosion in
agricultural lands.
What is the relationship between soil texture and erodibility?
Soil texture, particularly the proportions of sand, silt, and clay, significantly influences the
erodibility of soil.
What equation relates soil loss (E) to slope (S) according to Smith and Wischmeier?
E = 0.43 + 0.3S + 0.04S², where E is in tons per acre and S is in %.
What is the relationship between slope length (L) and erosion according to Zingg (1940)?
E ∝ L^0.6, indicating that erosion is proportional to the slope length raised to the power of 0.6.
What is the formula for calculating the slope length factor (L)?
L = x / 22.13, where x is the slope length in meters.
PROCESSES AND IMPACTS FINAL EXAM
QUESTIONS AND 100% VERIFIED
ANSWERS!!
How do soil properties influence soil erodibility?
Both classes of properties are influenced by the nature of the soil and the management or
treatment it undergoes.
What concept did Middleton (1930) consider in relation to soil erodibility?
Middleton considered the dispersion ratio (%), which is the ratio of the weight.
What is the erosion ratio defined as?
The dispersion ratio divided by the ratio of colloid to moisture equivalent.
What indices of soil erodibility (K) were suggested by Bhatia and Srivastaria (1954)?
Dispersion ratio, clay ratio, silt to clay ratio, and soil aggregation.
According to Wang and Lin (1970), what are the principal determinants of soil erodibility
for arable soils?
Aggregate stability and clay content.
What five soil properties did Young and Mutchler (1977) find explained 90% of the
variations in erodibility of Minnesota soils?
Particle size distribution, bulk density, aggregate index, dispersion ratio, and the amount of
montmorillonite.
What relationship did Marquez (1980) find regarding soil erodibility (K) and water stable
aggregates?
K is inversely proportional to water stable aggregates, hydraulic conductivity, bulk density, and
carbon to nitrogen ratio.
,What did Wischmeier and Mannering (1969) conclude about soil erodibility (K)?
K is a complex interaction of soil physical and chemical properties.
List some factors that influence soil erodibility according to Wischmeier and Mannering
(1969).
Particle size distribution, organic matter content, pH, structure, bulk density, steepness and slope
shape, pore space filled by air, aggregation, residual effects of vegetation, and chemistry of
parent material.
What type of soil is considered the most erodible?
Soils that are high in silt, low in clay, and low in organic matter content.
How does the silt fraction affect soil erodibility?
A soil usually becomes less erodible with a decrease in its silt fraction, regardless of whether
sand or clay increases.
What is the effect of organic matter (OM) on soil?
OM improves soil aggregation and the infiltration capacity of soils.
What does the formula for soil erodibility (K) include according to Wischmeier and
Mannering (1969)?
K = OM + S + C, where OM is organic matter content, S is % sand, and C is the clay ratio.
What is the relationship between slope and erosion processes?
Increasing slope generally increases the rates of erosion processes.
What happens to runoff flow regimes as slope length increases?
Runoff flow regimes change, leading to a bigger build-up of surface runoff or deeper runoff
depth.
What is the consensus among researchers regarding the effect of slope on soil loss?
E is proportional to S raised to an exponent b, but there is no consensus on the value of b.
, What equation did Smith and Whitt propose for claypan soils?
Re = 0.1 + 0.21S^(4/3), where Re is the relative soil loss to unity loss from a 3% slope.
What is the significance of the bulk of available data regarding slope and soil loss?
The data is not in agreement on the effect of slope on soil loss.
What does the term 'relative soil loss' refer to in the context of slope?
It refers to the comparison of soil loss from different slopes, often expressed in relation to a
standard slope.
How does increasing slope length affect detachment by runoff?
Detachment by runoff increases with increasing slope length as the hydraulic radius increases.
What is the role of aggregation in soil erodibility?
Aggregation improves soil structure and reduces erodibility.
What are the implications of soil erodibility for agricultural practices?
Understanding soil erodibility helps in managing soil conservation and preventing erosion in
agricultural lands.
What is the relationship between soil texture and erodibility?
Soil texture, particularly the proportions of sand, silt, and clay, significantly influences the
erodibility of soil.
What equation relates soil loss (E) to slope (S) according to Smith and Wischmeier?
E = 0.43 + 0.3S + 0.04S², where E is in tons per acre and S is in %.
What is the relationship between slope length (L) and erosion according to Zingg (1940)?
E ∝ L^0.6, indicating that erosion is proportional to the slope length raised to the power of 0.6.
What is the formula for calculating the slope length factor (L)?
L = x / 22.13, where x is the slope length in meters.
