Large-scale stresses, decay of River Jamuna and resilience strategies in the Anthropocene

In the recent decades, many worlds' large rivers have been exceptionally modified by human interference. The principal objective of this study is to investigate the causes and consequences of decay of river Jamuna (distributary of river Bhagirathi-Hooghly). The entire investigation was conducted by the data of historical maps like Rennel's map of Bengal, Hunter's map, digital version of US army map, landsat satellite imageries (1980-MSS, 1990-TM, 2000-TM, 2010-ETM+ and 2020-OLI) and fluvio-hydrological study. Maximum likelihood classification algorithm was used to delineate the land use and land cover classes and Kappa based accuracy assessment indices were also used for the validation. There is no scientific work on this historically important river and afterward, millions of people are also underprivileged from this river ecosystem services due to severe degeneration. In this milieu, it is a genuine research gap. Novelty of the work is exposed the authentic causes of river decay and anthropogenic stressors. Result showed that the average width of river Jamuna has been significantly decreased whereas maximum average width of the channel was recorded in the year 1956 (319.81 m) and the present channel is flowing comparatively within narrow path (69.27 m). Rate of siltation (average rate of siltation 0.23 m/year) on channel bed has been increased due to impacts of channelization. Channel bed, natural levee and proximity floodplain have been encroached by large scale human intervention. LULC patterns showed that the urban built-up area is rapidly amplified from 2000 (22.26%) to 2020 (31.50%) whereas, agricultural and swampy land turned into built up area. Off-take of Jamuna is completely detached from the parent river Bhagirathi-Hooghly in the early 1956 and gradual anthropogenic interferences within river corridor accelerate river decaying processes. River restoration is highly required for sustainable river ecosystem health management and environmental development. Some management strategies have been recommended such as reconnecting of river Jamuna with Bhagirathi-Hooghly, dredging, decommissioning of culvert and sluice gate, cleaning of fishing pool and water hyacinth and sustainable land-use planning.