EXPERIMENTAL-STUDY OF PROCESSES AND PARTICLE-SIZE DISTRIBUTIONS OF ERODED SOIL

The study presented here consists of rainfall-runoff events produced with a large rainfall simulator. Three test plots were 2.44 m wide, with lengths of 6.1 m, 13.72 m, and 24.38 m, and a slope of 2%. The soil on the plots was loamy sand. Rainfall intensities of 44 mm/h, 79 mm/h, and 160 mm/h were run for 1 h for each test. Samples of the runoff were analyzed for sediment particle-size distribution, which led to several conclusions about the processes governing the erosion rates. Transport capacity tended to limit the erosion rate of larger particles, and supply limited the erosion rate of smaller particles. The data demonstrate that evaluating a single detachment or transport rate and assuming that it is constant for a season, or even a storm, may not always produce accurate results. The variations of these rates, due to armoring, must be taken into consideration.