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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.
From the change in diameter of the hole over time, the rate of erosion can thus be plotted against applied hydraulic shear stress and fit to the following equation: [1] [4] = where E r is the rate of erosion over time, k d is the soil erodibility, and τ c is the critical shear stress for erosion.
Few soil erosion models consider gully erosion, mostly due to difficulties in modelling these large erosional features. Several studies have evaluated the ability of soil erosion models to realistically predict measured rates of erosion, mainly on agricultural landscapes. There is often a wide discrepancy between predicted and observed erosion ...
Soil erodibility is a lumped parameter that represents an integrated annual value of the soil profile reaction to the process of soil detachment and transport by raindrops and surface flow. [1] The most commonly used model for predicting soil loss from water erosion is the Universal Soil Loss Equation (USLE) (also known as the K-factor ...
The jet erosion test (JET), or jet index test, is a method used in geotechnical engineering to quantify the resistance of a soil to erosion. 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 .
But because of the complexity of soil erosion and its constituent processes, all erosion models can only roughly approximate actual erosion rates when validated i.e. when model predictions are compared with real-world measurements of erosion. [108] [109] Thus new soil erosion models continue to be developed. Some of these remain USLE-based, e.g ...
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.
In its early stages of development, soil loss tolerance rates were inconsistent because they were obtained based on rough estimates. From 1961 to 1962, several groups of soil in the United States were designated with T rates ranging from 2 to 6 tons per acre per year. The rate was subsequently adjusted to 1 to 5 tons per acre per year. [5]