The Theoretical Approach to the Modelling of Gully Erosion in Cohesive Soil

The stochastic gully erosion model (STOGEM) is based on a combination of deterministic mechanics and a stochastic description of the erosion control factors. The main proposition in the model is that the depth of the active surface layer of eroded cohesive soil is equal to one particle diameter, and the deposition of eroded particles is negligible. The erosion rate at the gully bed is calculated directly from the equation of the balance between driving and resistance forces acting on soil particles in flowing water using the probability density functions of stochastic variables: flow velocity, soil aggregate size and cohesion. Probability density functions of cohesion in the model vary through time and space during the erosion event due to the changes in soil composition—armoring and loosening. This theory is still far from achieving practical application, but opens up a new way for better understanding the experimental results of gully erosion and shows the direction for future investigations