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United States Department of Agriculture

Agricultural Research Service

Title: On Tracking Sediment Particle Sizes in Furrow-Irrigation Induced Erosion for Modeling Phosphorus Transport

Authors
item Strelkoff, Theodor
item Fernandez-Gomez, R - SPAIN
item Mateos, L - INSTITUTE DE AGRIC SPAIN
item Giraldez, J - DPTO DE AGRON SPAIN
item Clemmens, Albert

Submitted to: US Committee on Irrigation and Drainage/Environmental and Water Resources Institute Conference
Publication Type: Proceedings
Publication Acceptance Date: April 1, 2003
Publication Date: July 1, 2003
Citation: Strelkoff, T., Fernandez-Gomez, R., Mateos, L., Giraldez, J.V., Clemmens, A.J. 2003. On tracking sediment particle sizes in furrow-irrigation induced erosion for modeling phosphorus transport. US Committee on Irrigation and Drainage/Environmental and Water Resources Insitute Conference. p. 423-433.

Interpretive Summary: An aspect of surface-irrigation performance is the erosion and transport of soil from which furrows are formed. From western Nebraska to the Pacific Northwest, as well as in other parts of the world, loss of soil fertility and discharge of eroded sediments, sometimes with phosphorus adsorbed, into receiving streams are significant problems. Like other measures of performance, sediment movement depends upon field hydraulic properties and system design and management. Simulation models applied to what-if scenarios can be a great help in arriving at proper design and management. Existing models based on a single representative soil-particle size are too sensitive to the selection of that size, and underestimate by far the total surface area of all sediments transported with the irrigation runoff. With phosphorus adsorption dependent primarily on surface area, it is essential that actual particle size distributions are incorporated into the model. The research reported is a work in progress, detailing the modeling strategies developed to date. When completed, the software is intended for use by federal agencies concerned with surface-irrigation management like the Natural Resources Conservation Service, consultants, and extension personnel.

Technical Abstract: An aspect of surface-irrigation performance is the erosion and transport of soil from which furrows are formed. From western Nebraska to the Pacific Northwest, as well as in other parts of the world, loss of soil fertility and discharge of eroded sediments, sometimes with phosphorus adsorbed, into receiving streams are significant problems. Like other measures of performance, sediment movement depends upon field hydraulic properties and system design and management. Simulation models applied to individual hypothetical events can be of great assistance in developing proper designs and management scenarios. Issues which arise when extending the single representative-particle-size approach in the erosion component of the simulation software, SRFR Version 4, to track individual size-fractions of the sediment mix through their entrainment, transport, and deposition, are described herein. In particular, the extension of existing empirical transport-capacity formulas to small silt particle sizes is detailed. The assumption that LaursenÂżs (1958) formula is sufficiently well grounded theoretically to warrant some application to sediment sizes smaller than those in his empirical database leads to plausible results. Ultimate justification will be based on comparisons of simulated sediment-load hydrographs with field measurements.

Last Modified: 8/2/2014
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