Tuesday, 10 October 2017

Tidal River Management: from illegal embankment breaching to formalized concept in long-term delta planning

Several delta oriented research programmes have developed an interest in studying Tidal River Management (TRM). The programmes that have put efforts in analysing the specifics of TRM include the Urbanizing Deltas of theWorld programme, the ESPA programme, and ‘my’ Dynamic Deltas research project. Also within Bangladesh, different institutions such as FAO, UNDP and BWDB are conducting research on the topic.

TRM geographically takes place in the coastal zone of Bangladesh. It concerns the temporary removal of polder embankments, which makes these lands liable to tidal flooding again (and temporarily also inhibits agricultural production). Tidal dynamics redistribute sediments, from the adjacent silted up river system, and deposit them on the polder lands. These rivers regain some of their original profile, and within the polder, land is heightened. After closing the embankment again, it takes another 2-3 years to take the polder lands into cultivation again.

Recently published studies interested in TRM are set up from an environmental science point of view (e.g. calculating sediment dynamics, river discharge and tidal flows) but also from a social sciences perspective (e.g. policy analysis, social learning, sustainable livelihoods). Although the list below is probably not fully complete, it gives you an idea about the various dimension of TRM that have most recently (2017) been published.

Mutahara et al (2017): TRM and social learning for adaptive management; Gain et al (2017): interdisciplinary approach towards TRM implementation; Karim et al (2017): local stakeholder analysis of TRM in beel Kapalia. Earlier studies include Nowreen et al (2014) on rationalizing TRM from an historic perspective, and a discussion on the potential effectiveness of TRM in hydro-morphological terms between Auerbach et al (2015) and Hossain et al (2015). There are other articles under construction.

In our article from 2017, Jeroen Warner, Shah Alam Khan and I discuss how past flood management interventions in Bangladesh have oscillated between adopting ‘closed’ or ‘open’ approaches, and how TRM is positioned as an ‘in-between’ intervention. We also note that TRM started not as concept that was being developed and implemented by hydraulic engineers, but as a local initiative, by the authorities referred to as ‘illegal embankment breaching’. Despite its downsides, the embankment breaching also came with advantages and in order to make it acceptable for policy makers and water managers to take it seriously, it needed to be scientifically studied and be given a concept.

From this perspective it is fascinating to see that TRM is currently being discussed within the context of long-term delta planning. The recently published draft version of the Bangladesh Delta Plan 2100 (link or link) is quite positive about the potential of TRM as an element of coastal management in Bangladesh: “When considered, however, as part of an integral strategy for the coastal zone, it may be of interest considering national stakes. This measure is also considered effective for the longer term.” BDP2100 draft, p.300. Moreover, the plan discusses 7 potential TRM locations, referring to a TRM Master Plan developed by BWDB in 2013.

So, a locally contested illegal embankment breaching has made it to a formalized concept being discussed at the highest policy levels in Bangladesh. I'm sure we'll hear much more about it in the coming years. 

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