LAUSR

Abstract Present study is an effort to quantify the bank erosion and bankline migration in the Upper Tapi River, India. The migration of banklines have been quantified during period 1977–2010 using satellite imagery, SOI topo-sheets and GIS tools at every 20 km chainages of the river. The bank erosion/deposition areas (km2) are also computed by dividing the river in 50 km stretches. The study indicated that, significant bank migration has occurred between CH: 300 km and CH: 350 km. Field investigations suggest that this phenomenon is due to the infilling of Hatnur Reservoir and its post-reservoir sedimentation. The right bank line has been observed to be more erosion prone than left bank line of the river due to presence of relatively soft geological formation in the right bank. The developed hydraulic geometry equations clearly indicate that flow depth increases rapidly with increase in discharge without a significant increase in width at Dedtalai stream gauging station. The analysis of the geomorphic effect of extreme flood events of the years 1994, 1998 and 2006 showed that the unit stream power, for same order of discharge of year 1994, at Dedtalai stream gauging station is higher than Burhanpur stream gauging station. Apart from the magnitude of unit stream power, the duration of flood event has been found to be significant parameter in geomorphic effectiveness of the flood events. The critical erosion/shifting prone locations are also supported with field visits undertaken in the study reach.