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Title: An evaluation of movable-bed tidal inlet models
Authors: Iowa Institute of Hydraulic Research.
Jain, Subhash C. (Subhash Chandra), 1938-
Kennedy, John F.
Keywords: Movable-Bed Models
Sediment Transport
Tidal Hydraulics
Tidal Inlets
Publisher: Coastal Engineering Research Center (U.S.) General Investigation of Tidal Inlets Research Program
Engineer Research and Development Center (U.S.)
Description: General Investigation of Tidal Inlets Report
Abstract: The objective of this study was to evaluate the effectiveness of movable-bed tidal inlet hydraulic models in predicting prototype behavior, by comparing model predictions with the observations made in the prototype, and to examine the scaling requirements for such models. Model studies of this type have been conducted in the United States and Canada only by the U.S. Army Engineer Waterways Experiment Station (WES). Seven model studies were conducted by WES during the period 1939 to 1969. The calibrations of five of these models, as measured by bed topography changes, are evaluated by means of quantitative indicators, including correlation coefficients and root-mean-square (rms) error. The values of correlation coefficients, disregarding measurement errors in model and prototype soundings, were generally low and those of rms error high. If combined model and prototype sounding errors of 2 to 3 feet (0.61 to 0.91 meter) were allowed, the correlation coefficients were somewhat higher and the rms errors lower. Evaluation of data from the Galveston Harbor entrance model revealed that the shoaling rates and distribution along the navigation channel predicted by the model are not in good agreement with the prototype data. It was concluded that the model reproduction of details of bed topography was less accurate than that which might have been obtained had the similitude criteria proposed here been used, and had more complete prototype data been available for calibration. Disagreement between model and prototype is believed to have been due to: (a) scale effects introduced by nonsimilarity of the physical processes; (b) insufficient prototype data for calibration and verification; (c) oversimplification of the available prototype data for use in the model study; and (d) experimental errors. In all cases, the prototype data utilized for model calibration were decidedly inadequate, and the similitude requirements followed, especially those related to the sediment, were deficient in light of recent advances in understanding of coastal sediment transport. A literature review was conducted to determine the present understanding of and practice concerning similitude requirements for movable-bed coastal inlet models. Similitude conditions for models of this type are recommended. Also, an appendix has been prepared by the WES to provide comments on the University of Iowa's findings as well as to provide additional information on the background and value of particular model studies.
Rights: Approved for Public Release, Distribution is Unlimited
Appears in Collections:GITI Report

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