Submitted to: The Global Farm Selected Papers from the International Soil Conservation Or
Publication Type: Proceedings
Publication Acceptance Date: May 25, 2001
Publication Date: N/A
Interpretive Summary: Erosion from irrigation furrows is a problem in several areas of the western U.S., resulting in loss of soil from the fields and sediments that end up in drains, streams, and lakes. It is important to be able to predict and model when erosion will likely occur and estimate the benefits of best management practices on reducing erosion. I measured erosion and sedimentation in irrigation furrows in Idaho, and then used the data to evaluate relationships that have been proposed to predict sediment transport and deposition. I found that the commonly used relationships did not match the measured data, and suggest an alternative relationship. More work is required before we can confidently predict sediment transport and deposition in irrigation furrows.
Technical 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, pre-formed 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.