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Comparison of Long-Term Observed Sediment Trap Efficiency with Empirical Equations for Coralville Reservoir, Iowa
Journal article   Peer reviewed

Comparison of Long-Term Observed Sediment Trap Efficiency with Empirical Equations for Coralville Reservoir, Iowa

C. O. Espinosa-Villegas and Jerald L. Schnoor
Journal of Environmental Engineering, Vol.135(7), pp.518-525
2009
DOI: 10.1061/(ASCE)0733-9372(2009)135:7(518)

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Abstract

Trapping efficiency (TE) is defined as the percent of particles that are retained within an impoundment. TE can vary from ⩽0% indicating no sediment is retained or is lost, to 100% where all the sediment is retained. In this paper a high quality, long-term data set (32years) was used to demonstrate that annual sediment trap efficiencies for a run of the river impoundment are variable. For water years 1973–2005, annual trap efficiencies for Coralville Reservoir ranged from 5.6 to 95.8%, with a mean of 74.7% and a median of 79.9%. Overall trap efficiency for the entire period was determined to be 80.3% and a detention time of 12.4days . A comparison of the observed long-term TE was done against different empirical TE equations that are commonly used (Brown, Brune, Churchill, Dendy, Heinemann, & USDA/Summit Co., Water District). The Churchill equation provided the best fit of the empirical trap efficiency equations (TE𝐶=79.1%) ; all other empirical TE relationships underestimated the observed trap efficiency with errors ranging from 13.7 to 33.1%. Bathymetric data show that since 1958 the reservoir has lost 11% of its flood storage capacity, and over 62% of its normal pool capacity. For the time studied (1973–2005) the loss of storage is estimated to correspond to 16.9×109kg of sediment deposited in the reservoir, resulting in an annual sedimentation rate of 5.3×108kgyear−1 .
 Civil and Environmental Engineering Occupational Health and Industrial Hygiene

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