The objective of this research was to determinate and modeling the runoff for different soils classes based on different simulated rainfall intensities (30, 60 and 120mm h-1) in different soils in Uruguay. A portable rainfall simulator with multiple nozzles was used to simulate different rainfall intensities. On each soil was measured the initial time and rate of runoff, rainfall (total, duration and intensities), direction of slope, crop residue and cover percentage, soil densities (bulk and particle), soil porosity (bulk, macro and micro), textural fractions (clay, silt and sand), initial and saturated soil moisture. The runoff was estimated with Smith's modified model. The accumulate runoff losses were 64, 32, 30 e 15% from the total rainfall, for Vertissolo 1, Chernossolo, Argissolo e Vertissolo 2, respectively. The relationship between initial runoff and the runoff rate was inversively, independently of the soil surface and rainfall conditions. Increasing rainfall intensity decreases the initial runoff time and increase runoff rate. Smith's modified model provides a better runoff estimated in soils with high soil moisture content.
runoff; soil physics; rainfall intensity; rainfall simulator
