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.