The sedimentology and dynamics of mega-dunes, Jamunariver, Bangladesh

This thesis quantifies the occurrence, morphology and flow dynamics of dune bcdforms in the main rivers of Bangladesh: the Jamuna, Meghna and Ganges. Field work was conducted as part of the River Survey Project (Bangladesh Flood Action Plan 24) between November 1993 and March 1996, hence encompassing two flood hydrographs. River surveying was accomplished using a differential global positioning system to obtain vessel position and high resolution echo sounders and side scan sonar to monitor bed morphology. Flow, turbulence and suspended sediment transport were investigated using an Acoustic Doppler Current Profiler (ADCP) which measured both the instantaneous three-dimensional velocity structure and the relative suspended sediment concentration for the entire flow column beneath the survey vessel. Dunes are ubiquitous in the…