Practices and debates on de-poldering and embankment removal in the Netherlands

The idea to investigate controlled flooding projects was to a large extent influenced by a publication (2006) by Dik Roth, Jeroen Warner and Madelinde Winnubst, who in a detailed way analysed how plans for river widening, de-poldering and restored flooding became heavily debated among policy makers and local residents in the Dutch riverine area from the 1990s. Although related situations occurred in the more distant past (e.g. embankment breaches due to storms, or the abandonment of polders that were agro-economically not viable to maintain), to purposefully remove or relocate embankments started to be discussed in the late 1980s and 1990s. These first initiatives (Ooijpolder, Rijnstrangen, Beersche overlaat) were heavily criticised, not in the last place because of the top-down nature of how such initiatives were presented to local residents. The effectiveness of such interventions, and the major uncertainties that come along with policy making, resulted in fierce debates among different stakeholders. It resulted in the cancellation of the initiatives.

Building on this in my own (collective) research work, the de-poldering of the Noordwaard polder in this respect showed (2013) several similarities when it comes to debating the needs and effectiveness of controlled flooding. Compared to the earlier initiatives, the de-poldering project was much more oriented towards local residents, in terms of participatory processes and the involvement of farmers in discussions about how to continue with agricultural practices and a new spatial plan for the now flood-exposed area. As we discuss in our published article from 2014, the final decision-making stretch could however still be seen as a rather top-down decision, to make an end to growing tensions between policy makers and local residents. 

I would like to highlight one particular conclusion in the article. The de-poldering of the area increases discharge capacities in the region. This 'fixed' discharge capacity also means that any obstruction to achieving this capacity is unwelcome. This concerns excessive growth of vegetation in the floodplain, but also the deposition of sediments within the de-poldered area. As discussed in a previous blog, in the case of Bangladesh, sediment deposition is concerned an important and integral element of Tidal River Management in the coastal polders in Bangladesh. Flood dynamics and sediment deposition increase land height, something that has been similarly proposed via the 'Wisselpolder concept' (rotational polder flooding). The set hydraulic discharge objective obstructs this 'strategic' and long term view on controlled flooding.

Taking these debates to a higher level, it has to be said that flood prevention remains the dominant approach in dealing with flooding in the Netherlands. At the same time, practices and debates on embankment removal are of continued interest and occasionally spark up. I have been able to map quite a number of initiatives that concern de-poldering or restoring managed flooding in different parts of the country. Quite recently the Young Wadden Academy organized a meeting on the topic, provocatively entitled ‘Ditching Dikes’? They were quickly to acknowledge that ditching dikes altogether is not really feasible – but it is interesting in the sense that it contributes to a broader discussion about how to deal with water and land related dynamics typical to deltas, how to respond to ‘peak dynamics’ (e.g. floods) under the influence of climate changes, and how we can give shape to sustainable delta landscapes. It is very interesting to see how this debate, but also how future flood management policies, will develop towards the future in the Netherlands. 

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.