Impact story

The Leuvenum stream: innovation lab for stream research

The Leuvenum stream is the innovation lab for stream research, not only for the Wageningen Environmental Research/ Vallei & Veluwe Water Board combination, but for Dutch water management in general. Here, new knowledge and innovations are put into practice to achieve the targets of the EU Water Framework Directive and other legislation. These include goals for water retention and storage, water safety, water quality, ecology, biodiversity and climate resilience. The knowledge obtained from this research can be applied within the catchment area and beyond.

The Leuvenum stream is now a showcase for the implementation of measures to introduce dead wood, and will also become a showcase for the creation of flood plain wetlands.

Ralf Verdonschot

Ecological gain

The Leuvenum stream system is unique in the Netherlands, both in terms of nature value and landscape value. Unfortunately, in the second half of the last century, the system went through a phase of strong degradation, resulting in the disappearance of unique natural values. By taking measures now to improve water quality/ hydrology and enhance biology, the stream will return to its former quality level, and may even exceed that.

Societal benefits

For society, the added value of restoring the stream has two dimensions:

Water safety downstream: increasing the retention capacity reduces the risks for local residents and adjacent plots downstream
The stream has an important recreational function (facets of this include tourism, experiencing nature, added value to forest areas). The stream now receives a lot of attention in the media, a sign of the increasing numbers of people appreciating the stream and of the increased appreciation of the measures that have been implemented (the stream has featured in nature programmes and other publicity has been generated)

Why are the measures and research in and around the Leuvenum stream special?

And can we translate the findings into conclusions and recommendations for other stream systems? The measures introduced and research done in the Leuvenum stream are special for various reasons. Firstly, because the measures implemented in the area work very well; so well that the area has become an example for site and water managers and scientists in the Netherlands and abroad. It is now a showcase for the implementation of measures to introduce dead wood, and will also become a showcase for the creation of flood plains.

Secondly, recovery projects have been carried out in the stream for a relatively long time, and these have also been monitored relatively well compared to many other projects in the country. The great interest in studying the stream dates back to the 1960s (including the studies conducted by the then National Institute for Nature Management) and there are even descriptions of the fauna from the beginning of the previous century; this makes it one of the best studied streams in the Netherlands. This is a perfect starting point for doing research and evaluating measures, because the changes that occurred in the system as a result of particular measures are clearly visible.

Thirdly, it is unusual for a stream of this size to be surrounded by so much land owned by conservation organisations. This makes the stream a perfect environment for experiments and testing of measures without causing problems for neighbours. In addition, the multiple stream structure of the stream facilitates scientific research (which sets strict criteria for a statistically substantiated test design). A clear test design is again very important for translating research results to other streams.

The problems facing the stream are found more widely on higher lying sandy soils, and therefore translatable to the situation in large parts of the Netherlands. The stream's unique location makes it possible to test all kinds of innovative research questions that cannot be realised in other places due to lack of space, intensive use of the adjacent land, etc. The Leuvenum stream is thus helping to advance stream restoration and water management.

Value of the conducted and upcoming research

As mentioned above, the innovative studies in the stream are very valuable for water management in the Netherlands (and beyond) in general. Wageningen Environmental Research and Vallei and Veluwe Water Board are thus playing an important role in the innovation of water management and recovery.

Future research will further examine the globally unique stream restoration measure of sand addition and will hopefully soon show the importance of restoration that involves connecting the stream to the dried-up stream valley. We will know how we can restore the sponge effect of a natural stream valley and what the benefits are for aspects such as water balance, nutrient flows and biodiversity. This is useful and directly practically applicable knowledge that can be used by water managers throughout the country.

Do you have a question about the Leuvenum stream? Ask our expert: dr. RCM (Ralf) Verdonschot

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Key research findings

Sand addition makes it possible to transform a incised and channelised stream into a more natural stream, where the lower lying parts of the valley are connected to the watercourse, and as a result
- a. This has a positive effect on the biodiversity in the stream valley; and
- b. Much more water can be captured during peak discharges resulting in a strong reduction of downstream peaks.
After a few months, sand addition results in a far more varied stream bed, consisting of a mosaic of habitat types and current velocities. Species associated with this type of stream benefit from the measure.

The places where sand addition was carried out have made a positive contribution to the stream's biodiversity and habitat. It is already clear that an innovative stream recovery measure has been developed in the Leuvenum stream, and that this contributes to achieving water targets such as those set by the EU Water Framework Directive. This measure can now be implemented in other parts of the catchment area and further afield.