Bend Oscillation
Bend Oscillation of the Padma River
The Padma River is a very dynamic river and it has meandering bend. The bend development and bend oscillation is prominent in this river. However, it is essential to assess the type of the channel whether it is stable or actively meandering channel. Besides, time-series satellite images analysis would help to assess the bend oscillation of the Padma River. Mawa Reach is taken as an example.
Oscillation of the bend over time
Dry season satellite images since 1973 indicates that there was a tiny channel along the right bank of the river while the main channel was along the left bank. In the following decade in 1980, the river become straight while the river started to move towards the right bank through initiation of the meandering bend in 1984. Later, the river shifted more towards the right bank in 1996 when the main channel was along the right bank and comparatively smaller channel along the left bank.
Moreover, similar planform development during 2002-2015 reveals that the shifting of the meandering bend towards the right bank is still continuous. It may continue next few years. This tells that the meandering bend of the river along the right bank is actively meandering channel. It follows a oscillation of about 20-25 years from its formation phase from meandering to straight to meandering. Bank materials along the left bank is less erodible. This is due to the presence of the clay materials. While the bank materials of the right bank is basically of loose materials (sand particle) compared to the left bank.
In summary, it illustrates that the presence of the clay materials along the left bank makes the stable. On the other hand, the right bank channel is actively meandering due to the existence of the erodible bank materials. Hence, it could be concluded that right bank channel is actively meandering which migrates the channel boundary while the left bank is more stable than the right bank.