PLOT LENGTH EFFECTS ON RUNOFF AND SOIL EROSION AT THE SPARACIA EXPERIMENTAL SITE

Explaining scale effects for runoff and erosion improves our understanding of erosion processes. In this investigation, plot length effects on event runoff per unit area, Qe, sediment concentration, Ce, and soil loss per unit area, SLe, were checked at the Sparacia (Italy) site. The most common result, occurring for the 57-62% of the events depending on the considered variable, was the lack of any scale effect. When scale effects were detected, they indicated that longer plots yielded smaller Qe and SLe values and higher Ce values. Rainfall characteristics did not explain the occur-rence of significant scale effects nor they were able to describe changes in the scaling exponent for Ce and SLe e. There was some sign that scale effects for plot runoff decreased as rainfall amount or its erosivity increased. Additional investigations on plot scale effects are advisable to clearly explain what factors control the response of plots differing in length.