TESTING ROUGHNESS INDEXES TO ESTIMATE SOIL SURFACE-ROUGHNESS CHANGES DUE TO SIMULATED RAINFALL

The performance of six soil surface roughness indices to describe changes in surface topography due to simulated rainfall impacts is studied. A new simple roughness index, based on fractal theory is presented. A non-contact laser reliefmeter was used to determine roughness profiles after three successive periods of simulated rainfall on an experimental field plot. All the computed roughness indeces are statistically sensitive to describe the surface roughness changes due to rainfall. However, the spatial indices: (1) fractal index (R2); and (2) the limiting slope (SL) and the limiting difference (LD) indices of Linden and Van Doren, can be computed using valid statistical procedures. They have more physical meanings and can be correlated with other indices. © 1990.