Difference between revisions of "Opijnen - Side Channel"
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==Site description== | ==Site description== | ||
| − | The river Waal is a major tributary of the Rhine. Near the village of Opijnen a number of groyne fields were closed off in 1984 by the construction of a longitudinal dike. | + | The river Waal is a major tributary of the Rhine. Near the village of Opijnen a number of groyne fields were closed off in 1984 by the construction of a longitudinal dike. This construction improves navigation conditions for ship traffic on the Waal by directing the flow more towards the center of the channel. This prevents unwanted sedimentation of the deep middle parts of the channel which are used by ships. The site is situated in the outer bend of a meander. By closing off these groyne fields the hydromorphological conditions were altered. Water flow was stopped, leading to static water bodies in the groynes. Also the sedimentation and erosion of the banks was hampered. |
==Measures selection== | ==Measures selection== | ||
Revision as of 08:48, 13 April 2010
Opijnen - Side Channel
Key features of the case study
Site description
The river Waal is a major tributary of the Rhine. Near the village of Opijnen a number of groyne fields were closed off in 1984 by the construction of a longitudinal dike. This construction improves navigation conditions for ship traffic on the Waal by directing the flow more towards the center of the channel. This prevents unwanted sedimentation of the deep middle parts of the channel which are used by ships. The site is situated in the outer bend of a meander. By closing off these groyne fields the hydromorphological conditions were altered. Water flow was stopped, leading to static water bodies in the groynes. Also the sedimentation and erosion of the banks was hampered.
Measures selection
National natural and ecology policy led to measures being taken to restore part of the natural flow and dynamics in the channel that the dike had severed. This was undertaken in 1994. To do this without influencing the main channel, openings were made at two points in the dike (entrance & outlet) and between the groynes. This allowed water from the main channel to flow through. In essence a side channel was created. The side channel has a flow during 99% of the year due to the bed level and the bottom sill at the entrance of the channel. The measure was taken in hopes of artificially creating biotopes that no longer exist along the heavilly modified river Rhine.
Success criteria
The project served as a pilot to monitor and analyse the effects. Scientific research was done on the channel to identify if the channel indeed served to (re)create habitat and biotopes that had disappeared due to channelization and artificial alterations of the Rhine and its tributaries in the Netherlands. The primary success criteria in this research were an increase in characteristic wading birds, fish and macro invertebrates.
Ecological response
Hydromorphological response
Monitoring before and after implementation of the project
Socio-economic aspects
Contact person within the organization
Extra background information
References
Related Measures
- Lower river banks or floodplains to enlarge inundation and flooding
- Remove or modify in-channel hydraulic structures
- Develop riparian forest
- Reconnect backwaters and wetlands
