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United States Department of Agriculture

Agricultural Research Service

Title: Preliminary Analysis of the Ncpa-Nsl Suspended Sediment Calibration System

Authors
item Derrow, Ii, R - NCPA, UNIVERSITY OF MISS
item Kuhnle, Roger

Submitted to: Federal Interagency Sedimentation Conference Proceedings
Publication Type: Proceedings
Publication Acceptance Date: December 4, 1995
Publication Date: N/A

Interpretive Summary: Accurate determinations of the rate of sediment being moved by a stream is necessary information because the 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 land. Accurate information on the rate of sediment movement is also necessary for operating models that predict the stability of watersheds for different management scenarios. An improved technique for measuring the rate of sediment movement by streams using an acoustic device is being developed in a cooperative project of researchers from the National Center for Physical Acoustics, University of Mississippi and the USDA National Sedimentation Laboratory. This paper describes a test tank which will be used to develop and test the acoustic sediment measuring device with known sediment concentrations. This acoustic sampler will greatly simplify the collection of critical sediment movement information on streams in agricultural watersheds.

Technical Abstract: A water/sediment recirculation system, driven by an impeller based pump, has been designed and built to maintain various sizes and densities of sediment in suspension. Acoustic backscatter models and algorithms will be developed to measure suspended sediment concentrations and size distributions. An impeller driven pump was chosen because they are relatively inexpensive and readily available. However, the impeller has an increased tendency to create cavitation over other pump types, so as part of the design process a simple equation was used to estimate and minimize the potential for cavitation. The first generation system has been built and simple acoustic backscatter tests have been performed on the water filled system and will be discussed. Test results indicated no impeller created cavitation, however, bubble production was caused by turbulence generated at the pump intake structure. Steps have been initiated to solve this problem. The design, construction and preliminary testing of the system will be discussed.

Last Modified: 10/22/2014
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