Submitted to: Proceedings of Sediment Monitoring Instrument and Analysis Research Workshop
Publication Type: Proceedings
Publication Acceptance Date: 2/11/2004
Publication Date: 5/1/2005
Citation: Kuhnle, R.A., Wren, D.G. 2005. Suspended sediment measurement: data needs, uncertainty, and new technologies. In: Gray, J.R., (Ed.), Proceedings of the Federal Interagency Sediment Monitoring Instrument and Analysis Research Workshop, September 9-11, 2003, Flagstaff, AZ, U.S. Geological Survey Circular 1276, pp. 8-15. Interpretive Summary: Sediment has been determined by the EPA to be the most common pollutant impacting the streams and rivers of the country. Excess sediment may fill reservoirs and reduce their capacity, may fill channels and cause flooding, may degrade water quality, and may cause instability of the channel banks which can cause the destruction of valuable agricultural and other lands. Yet current state-of-the-art techniques to measure sediment moved by streams are labor intensive, expensive, and may be dangerous to use during runoff events caused by high-intensity storms. This paper is a report that summarizes and synthesizes the results from a breakout session on current and new technologies to measure sediment that is moved in the water column by streams and rivers. Existing and current suspended sediment measurement techniques were presented and discussed during the workshop. Promising technologies and recommendations for future work were developed. One of the pressing needs identified at the workshop was the recognition that an unbiased entity was needed for the testing of new technology sediment sampling equipment as they are developed. An unbiased testing group would certify that new technology sediment measurement devices measure sediment movement rates accurately and prevent untested sediment samplers from gaining widespread use.
Technical Abstract: Changes in the amount of sediment carried by a stream or river have been identified as the single largest reason for their being listed as impaired on the 1996 National Water Quality Inventory (Section 305(b) Report to Congress). Accurate assessments of total sediment loads can be used to identify unstable stream corridors and degrading landscapes, to assess best management and stream stabilization techniques, and to evaluate stream rehabilitation techniques. Accurate determinations of suspended sediment concentrations are essential to assess the impact of sediment on the watershed. In many stream systems, transport of sediment suspended in the water column is the main process by which sediment is moved. Yet collection of suspended sediment data using standard techniques is labor intensive and expensive, while prediction of suspended sediment loads is usually uncertain. To increase suspended sediment data coverage, manpower needs and costs need to be lowered and predictive capabilities need to be improved. Breakout session 1 was responsible for providing information and recommendations on emerging technologies that have potential for meeting the data and uncertainty needs of sediment users for in-situ measurement of suspended-sediment concentration. The specific goals of this session were to define the accuracy and frequency needs of sediment users, and to identify the most promising emerging technologies that will be available in the near term (3-5 years) to meet those goals.