Soil Erosion Equation (USLE) factors (R, K, L, S and P), Soil Erodibility
Factor (K) is one of the most important and key factors which determines soil
particles resistance to be detachment by water erosion (rainfall and/or runoff)
forces. In fact, K factor is the rate of soil loss per rainfall erosion index
unit and affected by 6 parameters including soil primary particles (silt, sand
and clay), organic matter content and also permeability and structure of soil.
The USLE nomograph is one of the most rapid and common methods for calculating
K factor based on mentioned parameters. In this study, 38 samples of surface
soil (0 - 15 cm) were collected from Yamchi watershed and the percentage of
silt, sand, clay and organic matter content were determined in soil laboratory. Also textures of soil
samples were determined to choice soil permeability and structure class codes
based on United States Department of Agriculture (USDA) published information.
Using USLE nomograph equation, K factor was calculated for each soil sample and
based on kriging interpolation method, soil erodibility factor (K) map was
constructed for entire study area which average soil erodibility factor and
average standard error of interpolated map were 0.442 and 0.0076 t·ha·h·ha-1·Mj-1·mm-1,