Jamuna–Brahmaputra River Natural Channel Design for Flood Control, Bank Erosion Protection, Navigation Improvement, and Land Reclamation

Abstract

During the last four to five decades, the Jamuna–Brahmaputra river system has been undergoing strong metamorphosis in width, bank erosion, and braiding intensities. The Government of Bangladesh (GoB) has clearly expressed in recent studies that, in addition to stabilizing the river course, the GoB is in favor of reclamation of floodplain land that was lost in the aftermath of the Assam Earthquake in 1950. This study shows that a considerable amount of land can be reclaimed by constructing a natural channel along the 264 km long Jamuna River from the Bangladesh–India border to the Padma River confluence. The natural channel includes a main channel with a width of 2 km and floodplains of 1.5 km width on both sides of the river. Meander belt analysis has been performed to delineate the morphologically stable channel of Jamuna River and to determine the alignment of the natural channel. From the analysis, the average amplitude and wavelength of the active meandering channel are found to be 1.7 km and 15.6 km, respectively. In addition, hydraulic and sediment transport models of the natural channel have been developed using surface-water modeling system (SMS) and sedimentation and river hydraulics-SRH-2D software. The hydraulic model determined the inundated areas along the natural channel for different flows varying from the lowest flow to the 100-year return period flow. The sediment transport model showed that if the Jamuna River is converted into a natural channel, the annual sediment load decreases more than 50% in the downstream. The conceptual design of the natural channel comprises four zones within the Jamuna River with different design criteria including sediment management, soft and comprehensive natural channel. Moreover, the study shows that the implementation of the conceptual plan will ensure a huge amount of reclaimed land, economic development, navigation improvement and give an enormous boost to the economy of Bangladesh.