Sediment Transport in Irrigation Furrows

*Thomas J. Trout, USDA-Agricultural Research Service, Water Management Research Laboratory, 9611 S. Riverbend Ave. Parlier, CA 93658. *Corresponding author: [email protected] ABSTRACT Sediment data were collected in southern Idaho irrigation furrows. Irrigation furrows allow detailed study of sediment transport relationships because of gradually decreasing flow rates in long, uniform, preformed rills. The measured trends of rapidly increasing sediment transport (load) with distance at the inflow ends of furrows (due to high erosion rates), maximum load near mid-furrow, and then decreasing load (due to net deposition) follows the expected basic processes. However, the measured high rates of sediment deposition are not predicted by transport relationships of the type used in the WEPP model. Also, the measured wide variation in sediment load over time on a field cannot be explained by sediment transport capacity concepts. An alternative sediment transport theory, not based on transport capacity, fit the furrow transport data better with fewer parameters and more consistent coefficients.