Over the past century, streams all over Western Europe have been straightened, enclosed, dammed up and adapted to handle as much and as fast a flow of water as possible. Together with eutrophication, this has led to a sharp decline in the ecological quality of brooks. Wageningen University & Research carries out research and provides advice on the management of stream valleys.
Stream valleys are characterised by a stream valley plain enclosed by higher ground, with a stream bed and river banks in between. The banks consist of sediment that is deposited when the brook overflows its banks. Often, besides the active stream bed, other water bodies are present in the valley.
In the previous century, brooks were straightened to increase the drainage capacity and thus reduce the risk of flooding. It now appears that brooks cut too deeply into the landscape, causing the surrounding landscape to dry up and the water to run off too quickly. As a result, upstream dehydration occurs and typical plants and animals disappear. These developments are counteracted by geomorphological stream restoration.
Geomorphological stream restoration takes into account:
- Restoring the habitat
- Making the brook/stream valley suitable for native organisms
- Retaining and storing water
- Climate change
- Restoring cultural-historical values.
Climate change will change the pattern of precipitation, causing periods of drought, but also periods of extreme rainfall. By constructing a buffer zone, the stream valley will be able to store more water. The buffer zone will reduce peak discharges because not all the water will end up in the stream at once, but will be discharged more evenly.
Ecology of the stream valley
The ecology of the area is also very important. For example, insects play a major role in the decomposition of organic material in the water. In order to increase the biodiversity in the stream valley, it is important to restore the watercourses. This creates a diverse landscape that is more attractive to animal and plant species. Introducing dead wood in the brook is a good way to increase the flow variation and heterogeneity of the brook, which also benefits the biodiversity and makes the brook valley more attractive.
Publications on brooks and stream valleys
A Bayesian network to simulate macroinvertebrate responses to multiple stressors in lowland streamsWater Research 194 (2021). - ISSN 0043-1354
Wood-induced backwater effects in lowland streamsRiver Research and Applications 36 (2020)7. - ISSN 1535-1459 - p. 1171 - 1182.
Over forty years of lowland stream restoration : Lessons learned?Journal of Environmental Management 264 (2020). - ISSN 0301-4797
Wood-induced backwater for lowland streams model: Wageningen University & Research
Lowland stream restoration by sand addition: Impact, recovery, and beneficial effects on benthic invertebratesRiver Research and Applications 35 (2019)7. - ISSN 1535-1459 - p. 1023 - 1033.
Connectivity and seasonality cause rapid taxonomic and functional trait succession within an invertebrate community after stream restorationPLoS ONE 13 (2018)5. - ISSN 1932-6203
Morphodynamic effects of riparian vegetation growth after stream restorationEarth Surface Processes and Landforms 43 (2018)8. - ISSN 0197-9337 - p. 1591 - 1607.
Oblique aggradation: a novel explanation for sinuosity of low-energy streams in peat-filled valley systemsEarth Surface Processes and Landforms 42 (2017)15. - ISSN 0197-9337 - p. 2679 - 2696.
Morphological assessment of reconstructed lowland streams in the NetherlandsAdvances in Water Resources 81 (2015). - ISSN 0309-1708 - p. 161 - 171.
Chute cutoff as a morphological response to stream reconstruction : The possible role of backwaterWater Resources Research 51 (2015)5. - ISSN 0043-1397 - p. 3339 - 3352.