Estimate average annual soil loss using the Revised Universal Soil Loss Equation (RUSLE)
How to Calculate Erosion Rate: The RUSLE Formula
The standard method for calculating soil erosion rate in environmental science and agriculture is the Revised Universal Soil Loss Equation (RUSLE). This formula predicts the long-term average annual rate of soil erosion caused by rainfall and runoff.
The equation is: A = R × K × LS × C × P
Variable
Definition
Typical Values
A
Computed soil loss (tons per acre per year)
Result
R
Rainfall-runnoff erosivity factor
20 to 500+
K
Soil erodibility factor (susceptibility of soil)
0.02 (low) to 0.69 (high)
LS
Slope length and steepness factor
0.1 to 10.0+
C
Cover management factor (vegetation/crops)
0.001 (forest) to 1.0 (bare)
P
Support practice factor (contouring/terracing)
0.1 to 1.0
Step-by-Step Erosion Calculation Example
Imagine a construction site or agricultural plot with the following characteristics:
Rainfall (R): 100 (Region with moderate rainfall)
Soil (K): 0.30 (Silt loam soil)
Slope (LS): 2.5 (Moderate slope length and grade)
Cover (C): 0.5 (Partial grass cover)
Practice (P): 1.0 (No specific erosion control practices)
The Calculation: 100 × 0.30 × 2.5 × 0.5 × 1.0 = 37.5 tons per acre per year.
Why Monitoring Erosion Rate is Critical
Calculating the erosion rate allows land managers to determine if the soil loss exceeds the "T-value" (Soil Loss Tolerance), which is the maximum rate of soil erosion that can occur while still permitting high crop productivity indefinitely. Typically, T-values range from 1 to 5 tons per acre per year. If your calculated A value is higher than 5, immediate intervention like silt fencing, cover cropping, or terracing is required.
function calculateErosion() {
var R = parseFloat(document.getElementById('rainfallFactor').value);
var K = parseFloat(document.getElementById('soilErodibility').value);
var LS = parseFloat(document.getElementById('slopeFactor').value);
var C = parseFloat(document.getElementById('coverFactor').value);
var P = parseFloat(document.getElementById('practiceFactor').value);
var resultArea = document.getElementById('erosion-result-area');
var outputDiv = document.getElementById('erosion-output-text');
if (isNaN(R) || isNaN(K) || isNaN(LS) || isNaN(C) || isNaN(P)) {
alert("Please enter valid numeric values for all factors.");
return;
}
var A = R * K * LS * C * P;
var interpretation = "";
if (A <= 5) {
interpretation = "Sustainability Note: This rate is generally considered within the sustainable 'Soil Loss Tolerance' (T-value) for most deep soils.";
} else if (A > 5 && A <= 15) {
interpretation = "Sustainability Note: This rate exceeds standard tolerance levels. Mitigation strategies are recommended.";
} else {
interpretation = "Sustainability Note: High erosion rate! Severe soil degradation is likely occurring. Immediate erosion control required.";
}
outputDiv.innerHTML = "Estimated Soil Loss (A):" + A.toFixed(2) + " tons/acre/year" + interpretation;
resultArea.style.display = "block";
}