Approach of Multifractal Parameters to Assessing the Soil Surface Roughness.

Soil surface roughness (SSR) is an important dynamic property that increases the retention and infiltration of water, reduces the volume and speed of runoff and influences soil losses by water erosion. This SSR property is measured in many studies about soil erosion. During the past few years, SSR analysis has focused on developing a unified conceptual framework for describing the geometric complexity of the data introducing the multifractal theory. So, field experiments were carried out, at the experimental station of EMBRAPA Southeastern Cattle (Canchim Farm), in São Carlos County, São Paulo State, Brazil.  Experimental plots of 33 m² were employed submitted to two tillage treatments and three repetitions. The two soil tillage system treatments were: no-tillage (SSP) and plowing plus disking (SPC). Three successive simulated rain tests were applied with 24 hour intervals among them. The rainfall intensities employed were: first rain with 30 mm/h, second rain with 30 mm/h and third rain with 70 mm/h. The surface roughness was obtained upon the chiseling tillage and each test of rain simulation, using a laser scanning method. Multifractal behavior analysis was applied to each matrix of the data set obtained with the laser scanning. The f(α)_singularity spectrum of multifractal was correlated to the roughness parameter for each experimental plot of two tillage treatment and for each rainfall simulations. The results shown that the multifractal parameters and the f(α) singularity were able to describe the complexity of soil surface roughness, the non-linearity behavior of the system, as well as, the future proposal to found out a best descriptor of roughness.