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Title: Sediment impact assessments for the Rio Guanajibo at Mayaguez and San German, Puerto Rico
Authors: United States. Army. Corps of Engineers. Jacksonville District.
Thomas, William A., 1938-
Keywords: Local flood protection
Flood control
Mathematical models
Project maintenance
Puerto Rico
Stable channel design
Sediment transport
Publisher: Hydraulics Laboratory (U.S.)
Engineer Research and Development Center (U.S.)
Series/Report no.: Miscellaneous paper (U.S. Army Engineer Waterways Experiment Station) ; HL-95-1.
Description: Miscellaneous Paper
Abstract: This sediment impact assessment was conducted for two protection projects on the Rio Guanajibo. San German is a channel modification project designed for a 10-year level of protection. The existing channel was analyzed using five stability tests in the computer program, "Hydraulic Design Package for Channels" (SAM), and found to be stable because the historical inflowing sediment discharge was sufficiently high to prevent erosion of the channel bed. The proposed project channel is wider than the existing channel and has a flatter slope. The analytical method for stable channel design indicated deposition would occur, and the sediment yield study predicted a trap efficiency of 59 percent. That trap efficiency is sufficiently high that a detailed sedimentation study should be conducted. Project reliability during the passage of the design flood event was tested using a sediment budget approach, also. The calculated trap efficiency is 33 percent. This is expected to cause about 1/3 m of deposition, most of which comes after the peak discharge, and the project is judged to be reliable. The Hormigueros-Mayaguez project is a levee project. The existing channel was determined to be unstable due to deposition at two locations. One was near the coastline and the other was near the upstream end of that project. This sediment impact assessment concludes that additional studies would be required to determine how rapidly the channel will fill in those locations. However, an alternative approach to the detailed sedimentation investigation, in this special case, is to recognize that these levees do not change the flow distribution or the water surface profile significantly from historical values in these reaches. Therefore, the long-term maintenance cost for dredging and bank protection with the project is expected to be the same as the local sponsor has experienced historically. If this approach is adopted, appropriate language should be included in the local cost-sharing agreement.
Rights: Approved for public release; distribution is unlimited.
Appears in Collections:Miscellaneous Paper

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