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<br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br /> <br />Figure 2 (below) shows streamlines of flow through <br />House Rock Rapid, and velocities along the streamlines <br />( in meters per second [mj s] ) . The streaml ines were <br />determined from floats launched upstream of the rapid. <br />Their trajectories were filmed from the camera station <br />indicated, and the velocities were determined by <br />measurement of the trajectories and elapsed time on the <br />films. The velocities increase from about 0.5 mjs <br />(1.6 ftjs) in the backwater upstream of the rapid (not <br />shown on this figure), to about 2.5 mjs (8.2 ftjs) at <br />the head of the rapid, to 6-7 mjs (19.7-23.0 ftjs) in <br />the narrowest part of the rapid, and then back to about <br />4.5 mjs (14.8 ftjs) in the jet that emerges next to the <br />eddy and beach downstream of the rapid. The velocities <br />of 6-7 mjs (19.7-23.0 ftjs) in the constriction here <br />appear typical of the rapids measured (to the date of <br />this report, velocities have been measured in Lava <br />Falls and Hance Rapid at approximately 7,000 cfs, and <br />in Horn Creek Rapid at 17,000 cfs in addition to House <br />Rock) . These velocities are among the highest <br />velocities ever measured on a river. <br /> <br /> <br />23 <br />