An investigation was conducted to describe the channel cross-section evolution near the bridge crossing of the Hatchie River at U.S. Highway 51 in Lauderdale and Tipton Counties, in West Tennessee. The study also included velocity and discharge distributions near the bridge crossing, and definition of streamflow duration and flood frequencies at the bridge site and comparison of these statistics with flows prior to the bridge collapse. Cross-section measurements at the site indicated that the channel was widening at a rate of 0.8 ft/year from 1931 through about 1975. The channel bed was stable at an elevation of about 235 ft. Construction of a south bound bridge in 1974 and 1975 reduced the effective flow width from about 4,000 to about 1,000 ft. Data collected from 1975 to 1981 indicated that the channel bed degraded to an elevation of about 230 ft and the widening rate increased to about 4.5 ft/year. The channel bed returned to approximately the pre-construction elevation of 235 ft as channel width increased. The widening rate decreased to about 1.8 ft/year from 1981 through 1989. Channel-geometry data indicated that recent channel morphology changes along the toe of the right bank have resulted in continued bank undercutting and bank failure. Cross-section geometry and flow-velocity distributions from measurements made from April 6 through 10, 1989, indicate that there is a high-flow meander pattern through this river reach and that the bridges are located at the point where the current strikes the right bank. (USGS)