Vreugderijkerwaard - Side channel

Vreugderijkerwaard - Side channel

• « Change Map size
• View in Google Earth

Site description

The Vreugderijkerwaard is a floodplain situated on the river IJssel, a tributary of the Rhine in the Netherlands. The area is characterized by a number of river dunes, which are a rare occurrence for the Netherlands. Since 1982 the area has been subjected to extensive grazing to preserve and develop the rivePart of the area, namely the river dune part, has been the property of a nature conservation organisation since 1962. This has led to a variety of rare plant species occurring in the area. The IJssel river was artificially connected to the Rhine in roman times, leading to the Rhine being the main factor of the IJssel's flow. The river was largely fixated through the use of groynes. Part of the natural meanders were removed through channelization measures.

Measures selection

Through the Vreugderijkerwaard a side channel was dug. This was done with for the Room for the River project in which flood protection,by increase in water retention area, and ecological recovery are linked. The project was co-funded by the EU-IRMA project. The measure of a flowing side channel was chosen to increase dynamic river processes in the otherwise fixated IJssel system. The side channel is artificially limited in its flow by divers. This measure was taken to avoid sedimentation of the main channel. The side channel has a flow-through of 1.5% of the average flow-through of the main channel. The flow speed of the side channel is lower then that of the main channel. This leads to sedimentation of sand and clay. To avoid the formation of islands in the channel and clogging of the channel a sand trap was installed.

Success criteria

In the project plan four main goals were formulated for the project:

1. Maintaining the unique river dunes in the area
2. Increasing diversity
3. Increasing river dynamics and promoting communities of organisms that benefit from higher dynamics
4. Attention for relations and connections to tributaries of the IJssel.

Another (secondary) goal was to keep recreational use of the area intact.

Related Measures

• Improve water retention
• Trap sediments
• Increase flood frequency and duration in riparian zones or floodplains
• Link flood reduction with ecological restoration
• Allow/increase lateral channel migration or river mobility
• Remove sediments
• Remove or modify in-channel hydraulic structures
• Lower river banks or floodplains to enlarge inundation and flooding
• Reconnect backwaters and wetlands
• Remove hard engineering structures that impede lateral connectivity
• Restore wetlands

Related Pressures

• Channelisation / cross section alteration
• Alteration of instream habitat
• Embankments, levees or dikes
• Sedimentation and sediment input
• Sand and gravel extraction
• Loss of vertical connectivity