A Cellular Automata Model for Soil Erosion by Rainfall

Cellular Automata (CA) are a powerful tool in order to model complex natural and artificial systems, which can be described in terms of local interactions of their constituent parts. Soil erosion is a complex phenomenon, which cannot be easily faced in terms of differential equations. It can be viewed in the CA approach as a dynamic system with discrete time and space, where space is represented by square cells, whose specification (state) describes the characteristics (substates) of the corresponding piece of space: altitude, water content, soil detached by erosion, water flows and so on. The neighbour of a cell c, which specifies the interacting cells, is given by its adjacent cells. A minimal model (SCAVATU) was developed; it accounts for the following components of the phenomenon: water loss by absorption, water flow, soil erosion by rainfall, soil erosion by water flow. SCAVATU was applied to the basin of the Fiumara Armaconi, 1.8 Km2 extended in the Calabria Region (Italy). The effect of the rainfall erosion is well known in this area, thanks to measures and observations during several years. The model was tested in a simplified context, where some substates take on averaged values. The first results are encouraging because, in the performed simulations, the eroded cubic metres of soil correspond adequately to the rainfall duration and intensity, and the majority of the areas of deeper erosion are identified.