Dyke reinforcement in Limburg

While the rest of the Netherlands has already lived for centuries with dykes, people in Limburg are only just getting used to the idea of them. This is due to the unique landscape; the river Meuse naturally lies lower than its surroundings, slicing into the landscape. This naturally created the plateaus of the Meuse, which act as a buffer against flooding. Residents sometimes had to move their household effects upstairs to keep them dry, but they didn't know any different. The floods in 1993 and 1995 put a different complexion on things, causing major inconvenience and jeopardising safety. Temporary dykes were quickly built in 1996, taking practical action as required, but without any coherent plan behind it. Initially temporary, these measures were later incorporated in the Dutch Water Act as primary defences, but they no longer meet the standards of today. The water discharge volumes to be expected are only set to increase as the climate changes. It should also no longer be possible for normative high water levels to breach the dykes, as is the case at present. The Limburg water authority, Waterschap Limburg, is faced with the major challenge of ensuring the basic safety of people living on the Meuse by 2024, sustainably protecting them from rising water levels. This sometimes has profound consequences for residents.

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We caught up with director Jos Teeuwen, technical manager Wout de Fijter, both from Waterschap Limburg, and Witteveen+Bos colleagues Patrick Mulder (contract manager) and Joey Willemsen (project manager for two dyke reinforcement projects) to talk about the programme.

The programme is also complicated by the landscape. Wout de Fijter: ‘This is the Meuse valley, not a flat polder like in the rest of the Netherlands. Existing dykes are connected to the high land around (known as high ground) or form small links between higher areas. As dyke engineers, we’re used to reinforcing existing dykes. When we reinforce here, we have to make new connections on the high ground and introduce new dykes to the landscape, which are sometimes more than twice the length of the existing dyke.  Sometimes we call it dyke introduction rather than dyke reinforcement.’

Patrick Mulder: ‘What we’re actually doing here is creating a new layer in the landscape. We take a critical look at the location of existing dykes and make sure they are in the right place for the long term. The emphasis here is not just on improving water safety, but also on strengthening the quality of the region. The things we do today will shape the landscape for years to come. This is the big difference from the stopgap construction of the temporary dykes in 1996, which were built in the face of urgent need. In addition to dyke reinforcement projects as part of the Flood Protection Programme, system measures are also being investigated as dyke relocations or retention areas on four other projects; Baarlo - Hout-Blerick, Thorn - Wessem, Arcen and Well. Here we are looking for the best combination of measures so that we can be sure that what we are doing now will continue to be a sustainable and cost-effective plan in the future.’

Things are also complicated by the fact that buildings are sometimes located very close to the Meuse and that there are major changes in the landscape. Joey Willemsen: ‘A good example here is Arcen, where many back gardens open virtually onto the Meuse, with just footpaths behind them. These people have a beautiful view of the river, but the location for the water safety measures runs right through their garden. There are already low walls in these places, but they would need to be far higher. For these people, that’s very intrusive – like suddenly having a two or three metre fence outside their back door. This compels us to work with the residents to find innovative, customised solutions.’ Wout: ‘You’ll sometimes need a different solution every 50 meters. That makes it all very complex.’ Jos Teeuwen: ‘More than anything else, you need to be able to explain the solutions you have chosen to people, using the right arguments. Why is a particular solution possible in one location but not a good idea in another? We’re very transparent about that; after all, our work is funded by public money.’

This programme lives up to the motto of the water authority: 'with the local community, for the local community'. Jos: ‘One striking example of this is the unanimous decision of a small group of residents from Kessel (11 homes) living along the smallest dyke in the Netherlands (145 metres): in consultation with the municipality and Waterschap Limburg they chose to forgo strengthening the existing flood defences. The residents, whose houses already stand on relatively high land, accept they will occasionally be faced with flooding. The programme team is now preparing for the relevant part of the flood defence to be taken out of the Water Act once certain formalities have been completed.’

To get the local community involved in the projects, residents, businesses and local governments are involved in the planning as much as possible. The task is clear, but development may differ, therefore offering plenty of scope for stakeholders to contribute their thoughts. The first six months of the programme alone saw some 800 contact moments with the local community, including drop-in evenings, kitchen table discussions and design workshops. Jos: ‘It's better to spend time beforehand doing things properly than patching them up afterwards. That’s just much more efficient.’

The collaboration method chosen by the engineering firms and the water authority is unique. Patrick: ‘Extensive collaboration is increasingly in vogue; you might come across it in the form of construction teams and alliances, but here we really take it much further. In a good way! We work in integrated teams – IPM teams (Integrated Project Management teams) - comprising a variety of roles that are filled alternately by people from the water authority and from the engineering firm. Everything is intermingled. Someone from outside probably wouldn’t be able to tell who was from which ‘blood group’. The IPM teams act as a single team with one objective.’

Joey: ‘Our integrated project teams are the real strength of this programme. You can see that everyone wants to go that extra mile for each other, regardless of their ‘blood group’. And that’s crucial in a programme where fifteen dyke reinforcement projects have to be explored, planned and prepared for implementation in a relatively short space of time – all in consultation with the local community. What we’re doing and how we’re doing it is actually new; there’s no handbook for it yet. This is a one-of-a-kind programme in the Netherlands on many levels. We are writing the handbook ourselves, laying the foundation for future projects in Limburg and the rest of the country. Not only in technical terms as regards innovation, but also in terms of the approach to the local community and programme, and the integrated collaboration.’ Wout: ‘Three years ago, we as a water authority mainly looked to the rest of the Netherlands. That’s gradually starting to change; the other water authorities are coming to us to see how we are organising and tackling this programme together.’