CHANNEL AND BANK STABILITY OF STANDING PINE CREEK AT STATE HIGHWAY 488 NEAR FREENY, LEAKE COUNTY, MISSISSIPPI by D. Phil Turnipseed and K. Van Wilson, Jr. Prepared in cooperation with the MISSISSIPPI STATE HIGHWAY DEPARTMENT Jackson, Mississippi 1992 Open-File Report 92-112 ILLUSTRATIONS 7. Cross section showing critical failure surfaces for channel banks on Standing Pine Creek 100 feet downstream from State Highway 488 near Freeny, 1988 8. Cross section showing Pine Creek 100 feet upstream from State Highway 488 near Freeny, 1988 9. Cross section showing estimated of near-future channel widening for Standing Pine Creek 100 feet downstream from State Highway 488 near Freeny, 1988 TABLES 1. Measured channel-bed elevation and change in channel-bed elevation (outside of scour hole) on Standing Pine Creek at State Highway 488 near Freeny 2. Botanical data collected in 1988 on Standing Pine Creek in the vicinity of State Highway 488 near Freeny 3. Dry bulk-unit weight and shear-strength properties of soils as determined from borehole tests on the right (east) bank of Standing Pine Creek about 120 feet downstream from State Highway 488 near Freeny ABSTRACT The channel bed of Standing Pine Creek at State Highway 488 near Freeny, Mississippi, was about 1 foot higher in 1991 than when the reach was channelized in 1973. Aggradation in this reach between 1973 and 1978 probably was greater than 1 foot because the reach of the channel downstream of State Highway 488 was dredged twice during that period. Aggradation since 1978 has been relatively small. From 1978 to 1991, bankfull channel widths remained about the same at the bridge and in the channel reach 500 to 6,000 feet downstream from the bridge but increased an average of about 15 feet in the channel-bed slope in the vicinity of State Highway 488 decreased from about 5.6 feet per mile in 1973 to about 2.8 feet per mile in 1987. The channel-bed slope in 1991 seems to be about the same as that in 1987. Based on botanical evidence, most recent bank failures seem to have occurred during the April 1979 flood. Rates of channel gradation processes and widening -- as determined from channel descriptions, discussions with local residents, and botanical evidence along the banks -- were used in conjunction with soil properties to estimated probable channel adjustments in the near future (10 to 20 years). With the exception of a scour hole downstream from the highway crossing, the channel bed seems to have stabilized in the vicinity of State Highway 488 and channel-bed instability is not expected to pose a significant problem in the near future. The bankfull channel width in the vicinity State Highway 488 could increase about 5 to 10 feet in the next 10 to 20 years. These projections are based on the assumption that no additional channel modifications and no unusually large destructive flooding will occur in the next 10 to 20 years. 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.