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The erosion index (EI, also called the erodibility index) is created by dividing potential erosion (from all sources except gully erosion) by the T value, which is the rate of soil erosion above which long term productivity may be adversely affected.
The Universal Soil Loss Equation (USLE) is a widely used mathematical model that describes soil erosion processes. [1]Erosion models play critical roles in soil and water resource conservation and nonpoint source pollution assessments, including: sediment load assessment and inventory, conservation planning and design for sediment control, and for the advancement of scientific understanding.
where R is the rainfall erosivity factor, K is the soil erodibility, [3] [4] L and S are topographic factors representing length and slope, and C and P are cropping management factors. Other factors such as the stone content (referred as stoniness), which acts as protection against soil erosion, are very significant in Mediterranean countries.
The difference in hydraulic head used to calculate the shear stress also does not factor in the energy dissipated due to flow recirculation and expansion losses downstream of the test specimen. Furthermore, estimating the diameter of the hole throughout the test using an assumed friction factor has been reported as problematic.
The test can be applied in-situ after preparing a field site, or it can be applied in a laboratory on either an intact or a remolded soil sample. A quantitative measure of erodibility allows for the prediction of erosion, assisting with the design of structures such as vegetated channels, road embankments, dams, levees, and spillways. [1]
Research indicates that soil movement commences when wind speeds surpass a critical threshold and the rate of erosion aligns with the cube of the friction velocity. Friction velocity, denoted as U ∗ {\textstyle U_{*}} , is a meteorological term for wind speed at the Earth's surface and can be quantified using the equation:
where R is the rainfall erosivity factor, [99] [100] K is the soil erodibility factor, [101] L and S are topographic factors [102] representing length and slope, [103] C is the cover and management factor [104] and P is the support practices factor. [105]
Conceptually, the process of tillage erosion (E Ti) can be described as a function of tillage erosivity (ET) and landscape erodibility (EL): [9]. E Ti = f(ET, EL) . Tillage erosivity (ET) is defined as the propensity of a tillage operation, or a sequence of operations, to erode soil and is affected by the design and operation of the tillage implement (e.g., the size, arrangement and shape of ...