LATERAL MOVEMENT AND STABILITY OF CHANNEL BANKS NEAR FOUR HIGHWAY CROSSINGS IN SOUTHWESTERN MISSISSIPPI by D. Phil Turnipseed Prepared in cooperation with the MISSISSIPPI DEPARTMENT OF TRANSPORTATION Jackson, Mississippi 1994 Water-Resources Investigations Report 94-4035 TABLE OF CONTENTS Abstract Introduction     Purpose and scope     Acknowledgements Description of the study sites     Buffalo River at U.S. Highway 61 near Woodville     Bogue Chitto at U.S. Highway 98 near Tylertown     Bogue Chitto at county road near Lehr     Homochitto River at State Highway 33 near Rosetta Determination of lateral bank movement     Aerial photography mapping     Mapping error     Sinousity computation     Geographic information system Channel-bank stability     Soil properties     Channel geometry Analysis of channel characteristics     Buffalo River at U.S. Highway 61 near Woodville     Bogue Chitto at U.S. Highway 98 near Tylertown     Bogue Chitto at county road near Lehr     Homochitto River at State Highway 33 near Rosetta     Sinuosity Summary References ILLUSTRATIONS 1. Map showing location of the study sites 2. Example of mapped tops of channel banks and apparent channel shift caused by errors introduced during mapping and digitizing for the Pearl River in the vicinity of U.S. Highway 84 near Monticello, MS 3. Map showing tops of channel banks in the vicinity of the U.S. Highway 61 crossing of the Buffalo River near Woodville, MS, in 1941, 1972, and 1983 and a meander cutoff that formed about 2 miles upstream of the crossing 4. Map showing tops of channel banks in the vicinity of the U.S. Highway 61 crossing of the Buffalo River near Woodville, Mississippi, in 1941, 1972, and 1983 5. Cross section showing probable critical failure surfaces for existing channel banks at the U.S. Highway 61 crossing of the Buffalo River near Woodville, MS 6. Cross sections from sounding made during discharge measurements at the U.S. Highway 61 crossing of the Buffalo River near Woodville, MS, in 1953, 1964, and 1990 7. Map showing tops of channel banks in the vicinity of the U.S. Highway 98 crossing of the Bogue Chitto near Tylertown, MS, in 1940, 1964, and 1985 8. Cross sections from soundings made during discharge measurements at the previous U.S. Highway 98 crossing of the Bogue Chitto near Tylertown, Mississippi 9. Cross sections from soundings made during discharge measurements at the previous U.S. Highway 98 crossing of the Bogue Chitto near Tylertown, MS, in 1950 and 1983 10. Cross sections from soundings made during discharge measurements at the existing U.S. Highway 98 crossing of the Bogue Chitto near Tylertown, MS, in 1984 and 1991 11. Map showing tops of channel banks in the vicinity of the county road crossing of the Bogue Chitto near Lehr, MS, in 1940, 1965, and 1985 12. Cross section showing probable critical failure surfaces for existing channel banks at the county road crossing of the Bogue Chitto near Lehr, MS 13. Cross sections from sounding made durig discharge measurements at the county road crossing of the Bogue Chitto near Lehr, MS, from 1982 to 1991 14. Map showing tops of channel banks in the vicinity of State Highway 33 crossing of the Homochitto River at Rosetta, MS, in 1941, 1965, and 1985 15. Cross section showing a probable failure surface for the existing right (north) channel bank at the State Highway 33 crossing of the Homochitto River at Rosetta, MS 16. Cross sections from soundings made during discharge measurements at the State Highway 33 crossing of the Homochitto River at Rosetta, MS, from 1953 to 1990 17. Graph showing change in sinuosity with time for the four study sited in southwestern Mississippi ABSTRACT The lateral movement and slope stability of channel banks near four highway crossings in southwestern Mississippi was studied by mapping meanders from aerial photographs taken at various times, evaluating available discharge measurements, and measuring existing channel geometry and soil strength properties at these sites. Rapid, unrestricted meander cuts and sandy banks are characteristics of all four sites. Maps of tops of channel banks indicate lateral movement was significant upstream of all four sites, and at three of the bridge sites. The development of cutbanks and localized channel-bank erosion has caused unstable conditions at three of the sites. No significant movement occurred at the U.S. Highway 98 crossing of the Bogue Chitto near Tylertown from 1941 to 1991 despite large floods in 1983 and 1990. Slope stability analyses indicated this site to be marginally stable. The maximum lateral movement indicated from maps of tops of channel banks was 680 ft of northward movement of the right (north) banks of the Homochitto River near the State Highway 33 crossing at Rosetta from 1941 to 1983. 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.