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|Title:||Model study of Prado flood-control dam : hydraulic model investigation|
|Authors:||United States. Army. Corps of Engineers. Los Angeles District.|
George, John F.
Santa Anna River
|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-89-19.|
Abstract: Tests were conducted on a 1:80-scale model of the Prado Dam and spillway to determine the adequacy of proposed modifications to the existing structure to convey the revised design flow of 615,000 cfs. These modifications were to serve as an interim solution until decisions were made either to make major design modifications to the existing structure or construct a new structure upstream of Prado Dam that would control downstream flow releases. Unsymmetrical approach conditions to the spillway resulted in poor flow conditions at the left and right abutments at the weir, which caused a reduction in the effective length of the weir. Test results indicated that installing long approach walls on either side improved flow conditions at the weir, but did not significantly increase the capacity of the spillway or improve flow conditions on the spillway. Therefore, dikes were installed on the left and right abutments to streamline approach conditions to the spillway, thereby improving flow conditions at the weir. With design conditions the water surface exceeded proposed wall heights along the spillway. Additional wall height was obtained by paving a small berm and existing topography along each side of the spillway. A wall having a warped surface also had to be placed on top of the berm at the downstream end of the spillway chute to redirect any flow that overtopped the paved berm back onto the spillway. Flow conditions downstream of the flip bucket were unsatisfactory, with large standing waves present in the exit channel and a large eddy present between the spillway exit channel and the earth dam. Maximum velocities of 11 fps were recorded along the toe of the dam with a discharge of 400,000 cfs. Due to the erodibility of the material in the exit channel, the potential is high for severe scour to occur in these areas with a major flood event. No noticeable backwater effects were observed from the constricted bridge crossing and highways just downstream of the spillway. The design discharge of 615,000 cfs simply submerges these structures.
|Rights:||Approved for public release; distribution is unlimited.|
|Appears in Collections:||Technical Report|
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|TR-HL-89-19.pdf||3.7 MB||Adobe PDF|