The Water Engineering and Management department studies natural defences against water. This ‘nature-based engineering’ does not just revolve around civil engineering and water, but also ecology, for example. ‘nature has always been changing, but never as abruptly as it does now.’
The Netherlands has been fighting a battle against water for centuries. This symbolism of water as the enemy was popular among 20th-century engineers. In the 21st century, there is more focus on natural processes and we speak of water management instead. But what will the Dutch water landscape look like in another century? The Water Engineering and Management department seeks the balance between nature and human needs.
Nature-based
In nature-based engineering, the aim is to build in collaboration with nature. Kathelijne Wijnberg is a professor of Coastal Systems and Nature-based Engineering and researches these and other natural solutions for coastal protection. She explains the concept: ‘A well-known example is the Sand Motor, an artificial sand dune near Kijkduin.
We used to dump a lot of sand on the coast every few years to prevent erosion, but in doing so we disrupted the ecosystem. The Sand Motor uses natural currents to gradually add sand to the beach and dunes over many years, ensuring that the dunes remain a safe water barrier while allowing vulnerable nature to flourish.’
The concept of nature-based engineering is not black and white. You cannot simply label technological solutions as either ‘nature-based’ or not. As Wijnberg points out: ‘It’s a spectrum where, at one end, you let nature take its course completely and at the other end, you have a strictly technological solution.’ Denie Augustijn, Associate Professor of Civil Engineering, adds: ‘The purest form of nature-based engineering is, for example, allowing a river free rein, but we don’t have that kind of space in a country like the Netherlands.’
Bee highway
There is, in fact, a wide range of different measures by which you can cooperate with nature to a greater extent in water management. Augustijn gives a few examples: ‘In one of our studies, we’re investigating what effect herb-rich plants have on the strength of a dike. These plants have a much more varied root layer than the grass that usually grows there. And in addition to creating a sturdy dike, all these beautiful flowering plants also form a kind of bee highway.’
'We actively seek out cooperation in these areas, not just with water managers but also with ecologists, among others. Nature-based engineering serves many different functions in nature. Besides acting as wave breakers, our salt marshes in the Wadden Sea are important for biodiversity and CO2 storage. This natural coastal protection preserves all kinds of unique species and captures CO2 while also reducing waves. If you can maintain all these functions, you kill several birds with one stone.
All these different interests often result in complex challenges. 'It's about finding the right balance. We want to base processes on nature as much as possible, without neglecting the importance of other functions. For instance, how can you give the river as much space as possible without it immediately over flowing if there are heavy rains. And if you give a river or stream free rein, you want to avoid one farmer suddenly gaining more land at the expense of another.'
Climate change
Despite the complex challenges, water managers are increasingly turning to these more natural solutions. This is largely due to the effects of climate change. 'According to the most recent climate scenarios by the Royal Netherlands Meteorological Institute (KNMI), it's possible that the sea level will rise by seventeen metres by the year 2300,' says Augustijn. 'With such prospects, there is no point in continually raising dikes. We need to come up with much more resilient solutions.'
Wijnberg points out that accelerated climate change is forcing us to rethink our approach. 'Nature has always been changing, but never as abruptly as it does now. With our highly urbanised delta, we are now facing challenges. We need to consider whether to stick with our current approach or adapt to the changing nature.'
Sustainability
‘At the same time, it’s important to stay realistic. Nature-based is not the solution to all problems.’ For example, there is still only limited knowledge about its sustainability. This is what Markus Berger, professor of Multidisciplinary Water Management, focuses on. ‘The problem is that everyone assumes that natural solutions are sustainable,’ Berger explains. ‘But how ‘green’ are they really? Just take the Sand Motor; all that sand has to come from somewhere. The impact of such concessions is still often overlooked.’ Berger also explores the life cycle of nature-based engineering, a relatively new approach. He emphasises its complexity: ‘Natural processes - like nature itself - don’t really have a finite lifespan. We need to compare traditional and nature-based solutions in order to develop protocols to properly analyse the life cycles of nature-based solutions.’ Ultimately, the researchers want to ensure that water managers draw inspiration from nature in a more structural way. ‘We want to make nature-based thinking mainstream,’ Augustijn stresses. It’s all about finding the right balance between the many different needs of society and nature; embracing adaptability.
