Example location of woody patches at the Leerinkbeek stream which is a tributary of the Ijssel river system in the Netherlands. Source: https://vliegvisverenigingheelweg.nl/beken.
An evaluation of water retention interventions and their local and regional effects in the discharge and water levels.
Fast flowing rivers may negatively affect the biodiversity and increase the high water levels in case of floods. In addition, fast flows may not allow to sufficiently recharge the groundwater levels which can ultimately cause more prolonged droughts. Therefore, river managers are considering to restore a more natural flow regime in the river tributaries or streams to increase their water storage capacity and/or infiltration to the ground water. Typical restoration measures in the Netherlands include the re-construction of the natural bends or the location of woody patches in the stream (see right photo). However, their effects are not clear regarding the discharge and water level changes particularly when generating an opposite stream course also known as backwater effect. Moreover, streams are typically assessed in isolation of their river system which is necessary to better plan these interventions on a regional scale.
Key goals: Fundamental understanding Innovative monitoring
Effects in the flow patterns and water levels due to typical stream restoration interventions and the coincidence in the discharge and rainfall patterns between a tributary and its river.
We analyzed intervention effects at the local and the regional level:
- At the local level, we first collected hourly data in four streams (water level and discharge) to look at the upstream and downstream effects of woody patches. We compared these measurements with calculations from the simplified representation of the woody obstruction (top right of the image). We also looked the flow pattern effects of two example locations with very sharp stream bends (top left of the image) by collecting discharge and water level data during low and high water levels.
- At the regional level, we looked at historical records (1999 to 2015) to understand the correlation of rainfall patterns and the coincidence of peaks in the discharge between a tributary and the river itself (bottom side of the image).
For whom and where?
River managers planning stream restoration projects in the Netherlands or abroad could take into account either the regional or local approach to decide about the strategic location of these type of interventions.
Data-collection methods: Field survey measurements Numerical modeling
Temporal scale: 1-10years Daily series Hourly series
Application development and findings
Findings at local level confirm that the geometry of the wood patch and the stream affect the relation between discharge and water level drop over the wood patches. Instead, medium and high discharge events in sharp bends show similarities in water level profiles (little changes in space and time), but differences in flow patterns due to backwater effects (i.e. opposite stream course). At regional level became evident that when a peak in the discharge coincides at the confluence between a tributary and its river, the backwater effect can increase. These findings were deduced from the following locations:
- The comparison of field measurements in four streams in the Netherlands (Tongelreep, Ramsbeek,. Leerinkbeek and Tungelroysebeek) and the outputs of a simplified representation.
- Measurements collected during the winter season of 2017-2018 for two sharp bends in the river Dommel.
- The coincidence at regional level between nine highest discharge peaks in the Meuse River and its tributaries, Dommel and Aa River.
Status for day-to-day practice
Water managers can take into account these insights to define the strategic location of a river restoration intervention. For example, backwater effects can be reduced by placing the wood patches at a strategic cross section. Our simplified representation was useful to predict these backwater effects but its limitations include the non-physical representation of the roughness coefficients due to the difficulties to measure this parameter in the field.
Key locations that we studied within this project from which two of them were part of the IJssel river system whereas the other were tributaries of the Maas river.
Spatial scale: Catchment Reach
Key locations: IJssel River (NL) Maas River (NL)
This section will be available as soon as possible.
Last updated: 19/06/2019
Explore the contact details to get to know more about the researchers, the supervisory team and the organizations that contribute to this project.
Wageningen University & Research
As soon as available, explore the storyline to get to know more about the main methods or prototype tools that were developed within this project.
Explore the output details for available publications to get a glance of the innovative components and implications to practice as well as the links to supporting datasets.
Research outputs are currently under review. Meanwhile, the following are the main conference proceedings for additional details about this project:
- Geertsema, T.J., Torfs, P.J.J.F., Teuling, R.J. , Eekhout, J.P.C., Hoitink, A.J.F. (2018). Parametric model of wood-induced backwater in lowland streams. In: Huismans, Y., Berends, K.D., Niesten, I., Mosselman, E (Eds.). The future river: NCR DAYS 2018 Proceedings. Netherland Centre for River Studies publication 42-2018, 8-9 February 2018, Deltares, Delft, pp. 82.
- T.J. Geertsema, P.J.J.F. Torfs, A.J. Teuling, A.J.F. Hoitink. Backwater development by woody debris in streams. In: A.J.F. Hoitink, T.V. de Ruijsscher, T.J. Geertsema, B. Makaske, J. Wallinga, J.H.J. Candel, J. Poelman (Eds.), Book of abstracts NCR days 2017, NCR Publication 41-2017, 1-3 February 2017, Wageningen University & Research, pp. 28-29.
- Geertsema, T.J., Hoitink, A.J.F., Teuling, A.J., Torfs, P., Weerts, A.H., Uijlenhoet, R. (2015). Simultaneous occurrence of discharge peaks in a large river and its lowland tributaries. In: G. Constantinescu, M. Garcia, D. Hanes (Eds.), Proceedings of the International Conference on Fluvial Hydraulics (River Flow 2016), 11-14 July, 2016, St. Louis, USA, pp. 1626-1632.
Take a look to the dissemination efforts and application experiences which are available in the news items and blogs.
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