FLOOD-FLOW CHARACTERISTICS OF A RECTIFIED CHANNEL, JACKSON, MISSISSIPPI by K.V. Wilson Prepared by U.S. Geological Survey in cooperation with the City of Jackson Geological Survey Research 1968 Chapter D PROFESSIONAL PAPER 600-D TABLE OF CONTENTS Flood-flow Characteristics at U.S. Highway 51 Flood Profiles of February 10 and May 21, 1966 Reference FIGURES 1. Relation of stage to velocity, discharge, and area for an earthen canal constructed for Hanging Moss Creek at Jackson, Miss. 2. Flood profiles of Hanging Moss Creek at Jackson, Miss. ABSTRACT Extreme changes in velocity, stage, and Manning's roughness coefficient n were observed during the first year after construction of an earthen canal for Hanging Moss Creek at Jackson, Miss. The channel, constructed during the summer of 1963, had a 30-foot-wide bottom, 2:1 side slopes, and 12-foot depth. On March 2, 1964, velicities of 7.8 feet per second were observed at a 5 1/2-foot depth in the clean channel and Manning's n was computed to be 0.025. By Octo- ber 1964, velocities of 3.2 feet per second existied at a 5 1/2-foot depth and Manning's n was computed to be 0.05 in the channel which was then lined with fairly thick vegetation consisting of small willows, weeks, and grasses. These obser- vations indicate that the values of Manning's n commonly used in channel recitification are low, and that the carrying capacity of earthen channel may be reduced 100 percent as a result of only 1 year's growth of vegetation. LizardTech's Djvu plug-in is needed to view these reports. CLICK HERE TO VIEW THE ENTIRE REPORT For questions or comments, contact K. Van Wilson.