Tuesday, 15 March 2016

Third paper submitted: Tidal River Management in Bangladesh

Some weeks ago I submitted my third article, written with inputs from Jeroen Warner and Shah Alam Khan, to the Water Policy journal. The manuscript is now in review - fingers crossed! A short summary/preview is presented below.

Flooding polders in the coastal zone of Bangladesh
In line with the first case study about de-poldering of and controlled flooding restoration in the Noordwaard polder in the Netherlands, this article goes into related practices in the southwest delta of Bangladesh. What came to be known conceptually as TRM (Tidal River Management) includes the temporary removal of embankments around polders or beels, which enables tidal dynamics to flow in and out of the area. This means that the polder lands are not available for agricultural production for a number of years. The decision to start a TRM project therefore is not easily taken: thousands of people have to temporarily relocate and find other sources of income during this ‘active’ phase of tidal flooding.

But initiating these embankment cuts has to a large extent been driven by a combination of prolonged and severe water related problems: water logging and insufficient drainage capacity within polders, and silted up rivers hampering discharge from the drainage canals into the open water. By opening up the lands, tidal dynamics simultaneously scour river beds and deposit the sediment on the lands. In this way, polder lands increased in height substantially in some cases. By doing so TRM resembles the historic practices of low ‘eight month embankments’ which prevented flooding until rice harvest, after which these embankments started to overflow and spread out floods during flood season, depositing sediments on the land.


These practice happen against a background of a delta described as a ‘fluid environment’ (Lahiri-Dutt and Samanta, 2013) and an interesting social-ecological delta history (Iqbal 2010). Over the last decades many hydraulic interventions have been proposed and sometimes constructed, in an attempt to improve water management and flood protection in the southwest delta region. What can be learned from our analysis is that over the years approaches have ‘penduled’ in between closed and open water management approaches. TRM may be seen as an ‘in between’ concept, as it builds on existing polder infrastructure, but also advocates for periods of ‘openness’ with tidal flooding entering and leaving floodplains. On a final note, TRM has triggered the interest of NGO's, as well as long term policy planners to consider these practices in water policy plans, as well as researchers trying to understand the hydro-morphological dimensions of the concept.

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