Water and soil driven land design

Much of the landscape of the Netherlands is designed to act like a colander. Ditches and canals ensure that water is drained quickly, and if somewhere gets too dry, water can be pumped up and directed there. This kind of manipulation has become unsustainable. The impacts of climate change mean the country is increasingly facing weather extremes such as floods and extended periods of drought. Water and soil quality are under pressure and groundwater levels are falling. That’s why, in 2022, the cabinet decided to adopt a new approach, one in which policymaking is actually governed by water and soil itself. What this means in practice is that the spatial development of the Netherlands will be largely determined by the water and soil system. What can we do, where can we do it – and what can’t we do?

From Zeeland to Friesland

“For the past few decades, water levels in the Netherlands have been determined by land use function,” says Daan Verstand, a researcher in climate adaptation in rural areas. “But if policymaking is to be determined by water and soil itself, you need to reverse your thought process. You might then come to the conclusion that current forms of land use, and therefore the water system, are no longer appropriate. That can often be very complicated.” Verstand is the project leader for Laag Nederland 2050 (Low Netherlands 2050), a project in which researchers at Wageningen are taking a close look at three regions that they consider models for other low-lying parts of the Netherlands: Friesland, Waterland-East and Schouwen-Duiveland. They’re exploring possible future scenarios in those regions for landscape design.

The three regions they’re focusing on are currently grappling with serious water problems. In both Friesland and Waterland-East, peat oxidation is a problem. Lower water levels are causing the peat to dry out, which means it starts to rot. That process leads to land subsidence and also releases a lot of CO2. “In the past, the water board would have lowered the water level to ensure the land continued to be suitable for agricultural use,” says Verstand. “But if in your reasoning you take the water and soil themselves as a point of departure, you really don’t want to be pumping the water away. Instead, you need to be looking at what you can actually do if you maintain that water level. Also, the water boards are aware that pumping water away is getting increasingly expensive.”

In the other area being used as a model – Schouwen-Duiveland – there’s a different set of challenges. That area, like other parts of Zeeland, is particularly vulnerable to salinisation: an increase in the salt levels of the soil, groundwater and surface water. There are few opportunities here for supplying fresh water. “The construction of a freshwater pipeline from the major rivers is now being considered,” says Verstand. “You don’t have to do that: you can also figure out which areas can maintain their supplies of fresh water so you don’t increase your dependence on external water supplies. Because that dependence actually makes the system more vulnerable to drought, for example.”

Reeds, rice and recreation

The changing climate is increasing the urgency of challenges such as peat oxidation and salinisation. So what are the options that remain for Friesland, Waterland-East and Schouwen-Duiveland? Verstand and his fellow researchers are working on different future scenarios for the three areas. “Low Netherlands 2050 has a positive outlook. We know that if policy is governed by water and soil as a starting point, it substantially limits what we can do, but we’re inspiring stakeholders to consider the land-use opportunities that would be opened up under this approach.”

In Friesland, Wageningen researchers have come up with several land-use options. Verstand summarises these as follows: “They could include new forms of food production, such as blueberries, cranberries or even rice. Another option is the cultivation of fibre crops, for the production of construction and insulation materials, for example. This means growing crops such as cattail, elephant grass and reeds, or tree species that thrive in wet conditions and also contribute to biodiversity. But you can also take a different tack, and pursue recreational options, plant cultivation for medicinal purposes or an energy landscape with solar panels.”

For each type of land use, the Wageningen researchers are sketching out the possible ecosystem services as a building block for a revenue model. For instance, reducing emissions or sequestering CO₂ in peat could become an important source of income. WUR is reaching out to provincial governments, water boards, local authorities and farmers as part of this. “On Schouwen-Duiveland, farmers are actively working with us on these ideas. We recently organised a session where they drew on maps of the region to indicate where drought and salinisation are issues. They’re the experts in this area.”

New life in the Leuvenum Forest

While Low Netherlands 2050 is focused mainly on how water and soil-led approaches would be applied to agricultural areas, other Wageningen projects are focused on nature reserves. In the Leuvenum Forest, a nature reserve in the northern part of the Veluwe region, WUR has been involved in the restoration of the Leuvenum stream for over a decade. The results are spectacular.

“Around the 10th and 11th century, people started interfering with the water by digging a canal in the woodland,” says Maarten Veldhuis, account manager and adviser at the Vallei en Veluwe water board. “This led to the creation of a fast-flowing stream that drained water away quickly. The strength of the current led to the stream gradually wearing away a deeper channel, which meant that, after a while, the water could no longer get out of the stream. This had major consequences for wildlife: the surrounding area no longer got wet, deer could no longer drink from the stream and aquatic vegetation disappeared.”

- Unfortunately, your cookie settings do not allow videos to be displayed. - check your settings

In partnership with WUR and Natuurmonumenten (the Society for the Preservation of Nature Monuments in the Netherlands), the Vallei en Veluwe water board embarked on a unique project: to raise the Leuvenum stream back up, using wood and sand. “It’s precisely the kind of material we gathered from the woodland for centuries,” notes Veldhuis. From 2014 to 2020, sand was deposited. Ralf Verdonschot, an ecologist at Wageningen Environmental Research, was closely involved. “We had to approach this carefully. If you just pour sand into the stream, it will kill everything in it. We made sure there were multiple sections where we didn’t deposit any sand. From there, fish and insects could reach the new sandy areas.”

Replenishing the sand in the Leuvenum stream had major hydrological impacts. The water could once again flood the woodland and sink into the soil. Previously, of the 10 million cubic metres of water flowing through the woodland every year, 2 million cubic metres used to remain there. The rest flowed through. Now it’s almost the other way around: 7 million cubic metres of water remain behind, replenishing the groundwater, while 3 million cubic metres flow through towards the Veluwerandmeer.

Within a few years, Veldhuis saw an “amazing ecological metamorphosis”. Drought-tolerant trees died off, but willows, alders and European white elms – typical of a wet woodland – returned. More plants grew, which brought more grazing deer. More flowers grew, increasing the number of butterflies. The stream also attracted rare species, including insects such as a type of water boatman, and the ‘beautiful demoiselle’ (a species of damselfly). And the positive effects went right down into the soil itself. “Soil pH is between 4 and 4.5 in the Veluwe region. That’s very acidic. “In the plains that get flooded with water from the stream, some 60 to 70 hectares, the pH level is 6.5,” says Veldhuis. “That’s very good for soil life, and soil life is the most important thing we have.”Verdonschot is equally enthusiastic about the changes in the Leuvenum forest: “The stream brought the forest back to life.” He sees the Leuvenum stream as a successful example of really being guided by water. “This is a nature-based solution. You make one intervention in the system, using natural materials, and then nature takes over.”

Nature may have flourished in the Leuvenum Forest, but there’s also been a clash of interests in the area. In the upstream agricultural areas, for example, the higher groundwater level caused problems for a farmer. “We commissioned independent research into the loss of income for farmers resulting from the restoration of the stream in this valley. We provided compensation for that damage jointly with the provincial government,” says Veldhuis.

Where to now for our water?

Verdonschot and Veldhuis see the Leuvenum stream as an example of how things should be done in other places. A few other projects involving sand replenishment are currently underway in the Netherlands, and there could be many more, according to Verdonschot. “There are plenty of other stream valleys where this could be appropriate. Right now, we’re looking mainly at nature reserves, but this could just as well be done in agricultural areas. There are many straightened streams there too, and drought is frequent.”

Low Netherlands 2050 is also already looking beyond the borders of Friesland, Waterland-East and Schouwen-Duiveland. “Based on the model areas, we’re now in the process of drafting a more general, overarching article. This will make the project more relevant to other stakeholders in the low-lying regions of the Netherlands,” says project leader Daan Verstand. “Some difficult and profound decisions have to be made. It can be helpful to take a long-term perspective with that: where exactly do we want to go with our water and soil, and what opportunities will that present?”