The movable-bed model study of Masonboro Inlet was undertaken to evaluate model predictions of inlet response to a major improvement project when verification is based on preconstruction conditions. Masonboro Inlet was chosen for the study because prototype survey data were available for the preconstruction condition of the inlet area, and hydrographic surveys had been performed at approximately six-month intervals subsequent to construction of the north jetty. The initial plan of study was to verify the model for the prejetty prototype data, install the north jetty, then operate the model for the period necessary to simulate the passage of time to the date of the latest hydrographic survey. Model results were to be compared to the prototype data to ascertain how well the model predicted the bed changes that occurred in nature. Only two of the four prototype pre-jetty hydrographic surveys were usable for model adjustment and verification. The time interval between the surveys was nine months (from the end of October 1964 to the first of August 1965). This nine-month interval was not adequate for model verification since there was insufficient change in the inlet hydrography to provide a satisfactory verification data base. A good model verification data base should consist of approximately 6 month surveys over a two year or more time period in order to document some substantial changes in hydrography and to relatively well isolate effects of major storms of dredging and filling operations. Thirty-nine model tests were made in an attempt to reproduce the prototype scour and fill patterns for the nine month period. An acceptable verification was not obtained for the nine month period being used as the data base; however, due to time and cost limitations, an arbitrary decision was made to use the best model results as a verification and to continue the testing program on this basis. No single model test produced results over the entire problem area which would be acceptable for continuation of testing. Some of the tests resulted in fair verification hayward of the beach line but unacceptable verification seaward of the beach line. Other tests produced the opposite result. An exhaustive analysis of the model data has indicated that it is quite probable that an adequate verification and successful test program can be effected. The principal problem is that the prototype data used for verification were inadequate. A nine month prototype period is not long enough for base data for verification unless substantial changes occur and unless the physical processes causing these changes (tide, wave height and direction, storm surge, etc.) are well documented. Model verification should be based on the two-year period of July 1966-July 1968 subsequent to construction of the north jetty which resulted in substantial hydrographic changes (both in terms of fill and scour and channel migration). It should be noted that this procedure also would satisfy the original objectives of the study (to evaluate model prediction of inlet response to a major improvement when verification is based on preconstruction conditions) since construction of a south jetty is planned._x000D_ _x000D_ NOTE: This file is very large. Allow your browser several minutes to download the file.
Interim Report on Masonboro Inlet, North Carolina, Movable-Bed Model Tests
Miscellaneous Paper ; H-76-14
1976
45701455
Report
Electronic Resource
English
Improvements for Masonboro Inlet, North Carolina: Hydraulic Model Investigation: Volume 2
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