Hajime Nakagawa

By Rocky Talchabhadel, Kenji Kawaike and Hajime Nakagawa

Southwestern Bangladesh has been seriously affected by perennial waterlogging over the last few decades. It is primarily due to excessive riverbed siltation outside the polders after the construction of embankments along both sides of the tidal rivers. These embankments de-linked the huge natural floodplains and restricted a gradual process of natural deposition inside the polders. An introduction of the tidal basin concept by temporary de-poldering (embankment cut) at some designated locations has substantially solved the issues. The current chapter looks at the historical practice of flood/sediment management, the evolution of embankments and their de-poldering, inclusion of Tidal River Management (TRM) in long term flood/sediment management, and discusses a technical aspect of flood/sediment dynamics across the tidal river system. The process of restoring beneficial tidal flooding by cutting embankment at certain locations, commonly known as TRM, is not a novel method. The TRM has started from age-old practice and proves technically one of the effective methods of sustainable flood/sediment management in the tide-dominated river system. It is an example of building with nature, where little human interventions are needed, and a resilient measure for waterlogging, drainage-congestion, and river-siltation.

Part of the book: River Basin Management