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Erosion of banks and channel migrations are usually common phenomenon and recurring geo-hazardous problem in the Brahmaputra-Jamuna river system of Bangladesh. The present study intensively analysed multi-temporal Landsat satellite imageries (Landsat MSS, Landsat TM, Landsat ETM+, Landsat OLI TIRS), historical documents (Hunter maps), and literature information employing Remote Sensing and Geographic Information System techniques, and estimation of braiding and sinuosity indices especially emphasizing channel bar development, braiding, and bank-line migration of the river. The computed braiding indices of the river were 1.5, 10.3, 13.4, 11.0, 10.6 and 14.6 for the year of 1853–1857, 1977, 1989, 2000, 2014 and 2018, respectively (overall deciphering increasing trend). Similar to the braiding indices, the sinuosity indices (2.58, 7.02, 9.92, 8.31, 7.42 and 11.25 for the same selected years) of the river have also been changed over time. During 1853–1857 to 2018, 766.7 and 1624.2 km2 of lands extensively eroded on the east and west bank, respectively at a rate of 4.8 and 10.1 km2 yr−1. However, from 1977 to 2018, the erosion rates were 14.4 and 12.5 km2 yr−1, respectively. High discharges, sediment transport associated with random bars formation related braiding expansion, and weak bank materials are presumably the governing factors for causing such simultaneous severe bank erosion and remarkable bank-line migration phenomenon. Although, from 1853–1857 to 1977 the erosion of the river followed the river flow direction. It is expected that the outcomes of this research can contribute further research on morphodynamic characteristics of the braided river for better understanding the river characteristics, the river hydromorphology, water and sediment transport, its bank erosion, and formulating protective measurement plan for their sustainable current flow path maintenance. [ABSTRACT FROM AUTHOR]

This study attempts to analyse the historical records and satellite images, and determines the dynamic morphological changes using Remote Sensing (RS) and Geographic Information System (GIS) techniques in order to delineate the paleo-course and the dimensions of the Brahmaputra River. Additionally, land transformations due to route change from Old Brahmaputra-Meghna to Jamuna River were also evaluated. The study revealed that owing to the route changes, the Jamuna River grabbed about 2817 km2 of invaluable land resources that were well developed. Whereas Brahmaputra-Meghna river course was associated with ∼4563 km2 newly developed lands which are currently being used for settlement, business, and agricultural purposes. Thus, if the river system changes its route again and follows the former path, the lands associated with the Brahmaputra-Meghna river course may again be scoured by the river. Hence, it is suggested that the necessary preparations should be adopted to maintain the current flow of the Brahmaputra through the Jamuna River which may help to protect the newly developed landmasses. Since the present route is straighter than the old Brahmaputra course, it would be easier to manage and maintain the current route of the Brahmaputra via the Jamuna River. Finally, a sustainable river basin management approach may be lucrative for both local as well as international communities. [ABSTRACT FROM AUTHOR]

Trace elements contamination in vegetables especially pumpkin is a major concern for public health where human beings are continuously exposed to trace elements through consumption of pumpkin grown in the trace elements contaminated abandoned soil. The present study was conducted to assess the geochemical speciation of essential and toxic elements in abandoned agricultural soil, contamination and bioaccumulation of essential and toxic elements in different tissues of pumpkin plant and probable risk to human health using an integrated research methodology. Soils and different tissues of pumpkin (Cucurbita pepo) plants were collected from agricultural fields around the tannery industries in Dhaka City, Bangladesh. The values of pH, electrical conductivity and organic carbon were ranged from 5.7 to 7.6, 16 to 44 μS/cm and 0.36–3.3%, respectively. The geochemical speciation analysis indicated that Cr, Ni, Cu, Fe and Zn were predominantly associated with the residual fraction followed by organically bound phase where As, Cd and Pb were associated with the weakly bound fractions (exchangeable and carbonate). The average concentrations of essential and toxic elements in plants parts were in the decreasing order of Fe > Zn > Ni > Cu > Mn > Cr > Pb > As > Cd. The concentration of Cr, As, Cd and Pb in vegetables were higher than the standard limits of elements in food, indicates that toxic elements may pose potential risk to the consumers. The translocation factor (TF) revealed that studied elements were more accumulated in leaves than roots. Considering health risks of essential and toxic elements due to pumpkin consumption, Cr, As, Cd and Pb caused non-cancer and cancer risk for the adult's inhabitants in the study area. [ABSTRACT FROM AUTHOR]