Author(s): Rashedul Islam; Maruf Dustegir; Munsur Rahman; Anisul Haque; Hajime Nakagawa; Hiroshi Takebayashi; Zhang Hao
Linked Author(s): Hajime Nakagawa, Hiroshi Takebayashi
Keywords: No Keywords
Abstract: The shifting and erosion of the bank of the river Jamuna, one of the largest braided rivers in the world, poses threat to human settlement, community structures, village, rural business center and agricultural land. Based on the results of the historical satellite imagery (Landsat images) for the last 40 years (at Kazipur, Sirajganj), it is found that the sand bars is providing additional flow deviation (mostly oblique flow) that is leading towards further bend development and bank erosion. A number of RCC spurs have been constructed to protect the river bank erosion since 2000s with some degree of failure and success. In order to quantify the impact of bar-bend interaction on flow processes at the above field site, several detailed flow measurement have been done using Acoustic Doppler Current Profiler (ADCP) along the eroding bank (near the right bank) including those RCC spurs. Results showed that due to the oblique flow and secondary current erosion varies year to year depending upon the local morphology and bar-bend interaction. Along the eroding bank, beyond the magnitude of sinuosity1.6, the Jamuna abandons its active course. It was found that the velocity near the bank site increases by 1.5-2.0times due to advancement of submerged char towards the country side from the river side. This strong turbulence erodes away the bed material at the toe of the bank and consecutively causes to failure of the river bank.
Year: 2018