Author(s): Mohammad Nazim Uddin; M Mozzammel Hoque; Munsur Rahman
Linked Author(s):
Keywords: Braided Jamuna river; Erosion; Bank protection structures; ADCP; Flow field
Abstract: To prevent bank erosion, different types of protection structures have already been constructed at the erosion prone area along the braided Jamuna River. Three types of bank protection structures have been selected for the present study. The massive hardpoint (revetment-like structure) is located along main flow at Sirajgang, the RCC spurs located at Betil-Enayetpur (along secondary channel) and the bandallike structures are located at Randhunibari (along secondary channel). 3-D flow field were measured using an Acoustic Doppler Current Profiler (ADCP) and velocity vectors along horizontal and vertical planes are presented. Flow separation at the upstream termination of the revetment-like structure is relatively weak and in the scour hole, primary vortex and secondary vortex is observed. At the upstream of RCC spurs, strong parallel flow is generated. The magnitude of the parallel flow velocity is higher than that of the approach velocity. Flow obliquely hits to the earthen shank of spur where damages are observed during monsoon. Flow separation at the end of the bandal-like structures is almost absent and lateral diversion of flow towards the main channel both from the upstream and the downstream of the structure is observed. The diverted flow has no adverse impact eroding the high homestead bar.
Year: 2010