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item Nichols, Mary

Submitted to: Federal Interagency Sedimentation Conference Proceedings
Publication Type: Proceedings
Publication Acceptance Date: 12/12/2005
Publication Date: 4/2/2006
Citation: Nichols, M.H. 2006. Monitoring coarse sediment particle displacement using a radio frequency identification system. Proc. 8th Federal Interagency Sedimentation Conference, April 2-6, 2006, Reno NV.

Interpretive Summary: Sediment is a primary pollutant on western rangelands. The sediment load during flash flood in the southwestern US is made up of very small particles, such as silts and clays, as well as very large particles, such as rocks and boulders. Sediment that is carried in transport is often deposited downchannel. Understanding how and where the coarse particles move is important for developing models for predicting the downstream impacts of sediment loads. An experiment was set up on the Walnut Gulch Experimental Watershed to track racquetball sized particle during runoff. A radio frequency identification system that is operated like a metal detector was designed for finding the particles after a runoff event. The system is also used to read an encoded data string sent from a transponder within the particle so that each particle has a unique identification tag. The system has been used to track particles during three runoff seasons and will continue to be used as part of long-term sediment transport studies.

Technical Abstract: Coarse particles make up a relatively high contribution to overall sediment yield in ephemeral alluvial channels. A radio frequency identification system was developed and implemented to monitor the displacement of coarse particles following runoff in two upland, ephemeral channels on the USDA-ARS Walnut Gulch Experimental Watershed in southeastern Arizona. Sediment transporting flows are typically of short duration with rapidly rising and falling hydrographs. Commercially available radio frequency identification components including transponders, an antenna, a reader, and software were used to develop a system for locating particles under field conditions. During the 2003 field season 124 particles were located following four runoff events in two ephemeral channels. A total of 340 particle positions were measured with a differential geopositioning system after each particle was located with the radio frequency identification system. The overall recovery rate was 96%. The passive transponder system offers the advantages of low cost, consistent results under harsh environmental conditions, and no need for a power supply in the particle. Buried particles can be located and identified without disturbing channel bed material. The radio frequency identification system can be used to efficiently collect data for developing sediment transport equations and improving mathematical models for simulating sediment transport under natural runoff conditions.