The influence of Jamuna bridge on river morphological changes
Influence of Jamuna Bridge on River Morphological Changes
Md. Sirajul Islam*
Supervisor: Prof. Shinji Egashira**
MEE 11626
ABSTRACT
Influences of Jamuna bridge on the changes of river morphology are investigated by the field data as well as by numerical computations using a 2-D depth integrated water and sediment flow model. The
Jamuna bridge was constructed on 1998, and reduced the river flood width from 14.00 km to 4.8 km.
Data analyses suggest that rapid morphological changes in terms of sediment deposition and side bank erosion occur in the upstream reach of the bridge site after its construction. The results obtained from the numerical computations also show unusual and unexpected morphological changes in the upstream and the downstream of the bridge structure. The author proposed a countermeasure to reduce the sediment deposition and side bank erosion and evaluated it numerically. The result suggests that the proposed countermeasure is effective against sediment deposition and side bank erosion. Keywords: Jamuna bridge, River Morphology, Sediment deposition, Bank erosion, Countermeasure.
INRODUCTION
Ganges, Brahmaputra and Meghna are the three major rivers in Bangladesh which make a complex river network named as GBM river system. The Brahmaputra river which is known as Jamuna enters
Bangladesh near Kurigram district and flows through the country from north to south. The Jamuna river along with the lower reach of Ganges divides the whole country in to two distinct halves. Before
1998, the Jamuna river was an unfortunate barrier for the north-western part of Bangladesh in direct road communication system.
Jamuna bridge was constructed in 1998 with a length of 4.8 km. The average flood flow width of the river used to be about 14.00 km. Construction of bridge creates a sudden contraction of the flow width.
Active side bank erosion was observed in the upstream and downstream reaches of Jamuna bridge within few years after the
Md. Sirajul Islam*
Supervisor: Prof. Shinji Egashira**
MEE 11626
ABSTRACT
Influences of Jamuna bridge on the changes of river morphology are investigated by the field data as well as by numerical computations using a 2-D depth integrated water and sediment flow model. The
Jamuna bridge was constructed on 1998, and reduced the river flood width from 14.00 km to 4.8 km.
Data analyses suggest that rapid morphological changes in terms of sediment deposition and side bank erosion occur in the upstream reach of the bridge site after its construction. The results obtained from the numerical computations also show unusual and unexpected morphological changes in the upstream and the downstream of the bridge structure. The author proposed a countermeasure to reduce the sediment deposition and side bank erosion and evaluated it numerically. The result suggests that the proposed countermeasure is effective against sediment deposition and side bank erosion. Keywords: Jamuna bridge, River Morphology, Sediment deposition, Bank erosion, Countermeasure.
INRODUCTION
Ganges, Brahmaputra and Meghna are the three major rivers in Bangladesh which make a complex river network named as GBM river system. The Brahmaputra river which is known as Jamuna enters
Bangladesh near Kurigram district and flows through the country from north to south. The Jamuna river along with the lower reach of Ganges divides the whole country in to two distinct halves. Before
1998, the Jamuna river was an unfortunate barrier for the north-western part of Bangladesh in direct road communication system.
Jamuna bridge was constructed in 1998 with a length of 4.8 km. The average flood flow width of the river used to be about 14.00 km. Construction of bridge creates a sudden contraction of the flow width.
Active side bank erosion was observed in the upstream and downstream reaches of Jamuna bridge within few years after the
References: Ashida, K. and Michiue, M., 1972, Study on hydraulic resistance and bed-load transport rate in alluvial streams, Proc Egashira, S., 2011-2012, Mechanics of Sediment Transportation and Channel Changes (Lecture Material), Water Related Disaster Management Course of Disaster Management Policy Kabir, M. R. and Ahmed, N., 1996, Bed Shear Stress for Sediment Transportation in the River Jamuna, Institution of Engineers, Bangladesh, Vol Kuroki, M. and Kishi, T., 1984, Regime Criteria on bars and braids in alluvial straight channels, Proc. Takebayashi, H., Egashira, S. and Okabe, T., 2003, Braided streams formed on beds with nonuniform sediment, Proc. 3rd IAHR Symposium on River, Coastal and Estuarine Morphodynamics, pp