Bringing in the tides. From closing down to opening up delta polders via Tidal River Management in the southwest delta of Bangladesh

Abstract

The southwest coastal delta of Bangladesh is not only geographically home to a dynamic interplay between land and water, and between fresh surface water and saline tides, but also to contentious debates on flood management policy. It has been argued that dealing with delta floods in this region boils down to adopting either open or closed approaches. This paper longitudinally structures the open-or-closed debate based on a number of emblematic water management projects in the region. Departing from a typical open wetland history, river and polder embankments increasingly started to constrain flood dynamics. Upheaval among rural populations in response to the negative impacts of hydraulic engineering plans and works coalesced in efforts to restore open approaches, synthesized in the Tidal River Management concept. Its resemblance to historic overflow irrigation is often used politically as a yardstick to challenge the dominant hydraulic engineering paradigm. This paper argues that dealing with floods in Bangladesh requires plans, policies and projects formulated against the historic background of complex interactions among social processes, environmental dynamics and technological interventions: a lesson to be incorporated in on-going policy-making processes and long-term delta management plans.

Widespread infilling of tidal channels and navigable waterways in the human-modified tidal deltaplain of southwest Bangladesh

“…These TRM projects have had some success in both restoring local elevation and scouring partially filled-in tidal channels, but results have also been mixed due to many social and engineering challenges that could prove formidable if applied at the regional scale and TRM is only feasible where there is still sufficient tidal flow (Rahman, 1995;ADB, 2007;Kibria and Hirsch, 2011;Khadim et al, 2013;Paul et al, 2013). Nevertheless, we maintain that long-term sustainability of the delta requires the proper management of both sediment and the tidal channels that disperse it, in order that elevation relative to rising water levels is sustained (see also Van Staveren et al, 2017).…”

Sediment management in tidal river: A case study of East Beel Khuksia, Bangladesh

“…They have discussed the implications of TBM on disaster management [7,8], livelihood [9], ecosystem and environment. Some of the researchers have discussed regarding the mainstreaming of TBM for participatory environmental governance [10], flood policy [11,12], climate change adaptation [13], drainage rehabilitation project [14] and suggested the conceptual framework [15,16] for sustainability. Very limited researchers [2][3][4]17] have attempted to numerically simulate the process of TBM.…”

Resilience of River Deltas in the Anthropocene

“…To arrest the infilling of channels, tidal river management strategies are being developed, which rely on temporary removal of an embankment to increase the volume of water moving in and out the adjacent tidal channel over a tidal cycle. Tidal river management counteracts channel siltation and raises the polder level, which mitigates subsidence (van Staveren et al, ).…”

“…10.1029/2019JF005201 river management counteracts channel siltation and raises the polder level, which mitigates subsidence (van Staveren et al, 2017).…”