TITLE:
Impacts of Dredging on Fluvial Geomorphology in the Jamuna River, Bangladesh
AUTHORS:
Md Mosiur Rahman, Md Sazadul Hasan, Moniruzzaman Khan Eusufzai, Md Munsur Rahman
KEYWORDS:
Sediment Transport, Erosion, Dredging, Satellite Image, River Morphology
JOURNAL NAME:
Journal of Geoscience and Environment Protection,
Vol.9 No.6,
June
7,
2021
ABSTRACT: Jamuna, a major braided river in
Bangladesh, has an enormous hydrological impact on the surrounding areas and
streams. Erosion and sedimentation in the Jamuna river cause a large flow
fluctuation and floods round the year. Bangladesh Water Development Board has
initiated a pilot capital dredging project in the Jamuna river in 2011-2012,
aiming to guide the flow to reduce the risk of failure of the city area and
right guide bundh of the Jamuna Bridge. This study explores the long-term role
of dredging on river morphology us-ing erosion-sedimentation numerical modeling
approaches. Primary data were employed in numerical models to estimate the
erosion-sedimentation and compared outputs with the real-time cross-sectional
variation at selected sections along the reach during 2012-2013. The analysis
suggested that the rate of sedimentation is higher (60% to 80%), where the
dredging alignment crosses through the existing sandbar/char. Moreover, a
cross-section com-parison revealed that the channel near Sirajganj Hardpoint
shifted towards the left (east) bank, and the channel within the study area
developed very fast along the right (west) bank. However, satellite image
analysis revealed that the major bankline shifting occurred from 2000 to 2010
and the channel shifting was observed from 2014 to 2018 along the reach,
mostly, after the construction of some river training works. The variation of
the channel per-sistence (40% - 100%) selected part of the study area in the
channel inci-dence map, indicating the rapid dynamic behavior of the river
morphology. This study showed a good agreement of measured data and simplified
em-pirical relationships to predict the long-term morphodynamic behavior of the
braided Jamuna river.