|Cochrane, T - SANTA CRUZ, BOLIVIA|
Submitted to: American Society of Agricultural Engineers
Publication Type: Proceedings
Publication Acceptance Date: November 1, 2000
Publication Date: N/A
Technical Abstract: The processes that govern deposition of sediment within a rill are fundamental to the study of erosion mechanics and subsequently our ability to accurately predict erosion with process-based models such as WEPP. An experimental laboratory apparatus, named the rill simulator, was used to study deposition in a 25cm wide rill that was set up under laboratory rainfall simulators. Sediment feeders were used to add sediment and water to the top of the rill as well as to the sides of the rill to simulate conditions of interrill erosion contribution as would occur in natural conditions. A laser scanner was used to quantify the amount of deposition that occurred after each experiment. Water flow velocity measurements and sediment concentration samples from the outlet of the rill were also taken during the experimental runs to quantify the deposition and sediment transport in the rill. The experiments were conducted using silica sand, glass beads, and artificial plastic/glass aggregates with average diameters of 330, 150 microns, and 3mm and specific gravities of 2.65, 2.5, and 1.25 respectively. Combinations of different flow rates, rainfall intensities, and sediment feed rates were studied for each sediment type at low slopes. The objective of these studies was to determine if shallow water flow as influenced by rainfall intensity and incoming sediment concentration had a significant effect on the deposition of sediment in a rill. Results showed that the interaction of rainfall intensity and flow depths had a more significant effect on deposition of particles of low specific gravity. It was also shown that under no rainfall and high intensity rainfall deposition was limited whereas under medium intensity rainfall deposition was greater.