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|Title:||Newburyport Harbor, Massachusetts. Report 2, Design for hydrodynamics, salinity, and sedimentation : Hydraulic model investigation|
|Authors:||United States. Army. Corps of Engineers. New England Division.|
Brogdon, Noble J.
White, Douglas M.
|Publisher:||Hydraulics Laboratory (U.S.)|
Engineer Research and Development Center (U.S.)
|Series/Report no.:||Technical report (U.S. Army Engineer Waterways Experiment Station) ; HL-79-1 rept.2.|
Abstract: Newburyport Harbor Model, a fixed-bed model with provisions for conversion to a movable-bed model, was constructed to scales of 1:300 horizontally and 1:100 vertically and reproduced all of Newburyport Harbor, the Merrimack River to the head of tidal influence, and a portion of the Atlantic Ocean adjacent to the harbor entrance. The model was equipped with the necessary appurtenances for accurate reproduction and measurement of tides, tidal currents, salinities, freshwater inflows, density effects, and other important prototype phenomena . Verification tests were conducted to make certain that the model hydraulic and salinity regimens agreed with those of the prototype. The agreement attained between similar model and prototype values were considered satisfactory. A second verification phase was completed and accepted in which shoaling and scour patterns in the entrance area for periods of 6 months and 1 year were simulated. The purpose of the model study was to determine the effects of proposed improvement plans on existing hydraulic, salinity, flushing, and entrance shoaling and scour conditions. Six plans were selected for extensive model testing. Test results consist of comparable measurements of tidal heights, current velocities, salinities, surface current patterns, dye dispersion, and shoaling and scouring for base and proposed improvement conditions. Analysis of these data indicates that none of the six plans would cause any significant overall effects to base condition tidal heights, salinities, or dye dispersion. The data analysis does indicate very significant changes in current patterns and magnitudes and in shoaling and scour in the entrance area and on the outer bar. Most effects were confined to the local area of the plan but generally influenced overall conditions throughout the estuary very little. Plans including the curved extension to the north jetty (Plans 3B, BE, and BX) would each result in a small reduction to the shoaling rates in the outer bar channel but would cause increased shoaling over the inner bar and seaward end of the channel to such a degree as to offset the gains realized in the outer bar channel. These three plans and Plan 2C would cause hazardous navigation conditions through the entrance due to the extremely high current velocities generated by the plans . Plans D and 3E had the least effects of any of the plans on entrance shoaling and scour. None of the six plans tested had any significant effect on shoaling and scour rates or patterns along the beaches and offshore areas. Each plan resulted in a general but small increase in shoaling along the eastern half of the north shoreline of Plum Island. Plan D provided complete protection of the north shoreline of Plum Island. NOTE: This file is large. Allow your browser several minutes to download the file.
|Rights:||Approved for public release; distribution is unlimited.|
|Appears in Collections:||Technical Report|
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|TR-HL-79-1-Report-2.pdf||39.79 MB||Adobe PDF|