Gabion Mattresses are a useful engineering solution, designed by Maccaferri to both mitigate flooding and protect banks from the aftermath of flooding and erosion.
Maccaferri is a global active force when it comes to the provision of flood mitigation and bank protection solutions. One primary product line used to mitigate flooding and erosion are Gabion Mattresses. In March 2003 Maccaferri India completed a flood mitigation project close to Paradip (India) that exemplifies aptly how Gabion Mattresses can be used against the flooding of rivers. We revisited the project in 2016 to check on its performance.
The River Mahanadi is situated 14 Km ahead of Paradip. The rivers Mahanadi and Debi were flooded following the devastating cyclone which hit the state of Orissa in the year 1999. The embankments and the river bank were severely eroded and thus required extensive reconstruction. Since the site is close to the Bay Of Bengal, small tidal waves (in the range of 0.2m-0.5m) are present in the river channel throughout the year.
These waves, combined with the velocity generated (2-3 meters/sec) have been instrumental in dislodging the existing protection work using rip-rap in some stretches and bamboo piling work in some other stretches. The average slope of the riverbank (after erosion) was observed by experts to be in the range of 1:1. The consultant wanted to provide a flexible solution that would eliminate extensive earth work.
The project turned out to be a World Bank aided project. The project involved the launching of pre -filled Gabion mattress in India. In the rehabilitation process, the eroded embankments and banks had to be reconstructed. The Gabion mattress was placed at a depth of 20 meters underwater. The Mattress were placed at a 12-meter distance from the bank. Ultimately, the embankment was reconstructed using locally available earth fill, compacted to 90% of the maximum dry density, as per Ministry Of Surface Transport standards.
The side slope of the embankment was protected with a 0.6m solid stone pitching. The dangerously unstable nature of the river banks called for a customized and premeditated solution that was executed as follows:
- the slope was stabilized via the loose dumping of 30-40 kg of rocks (rip rap used to form a bank slope of 1:2)
- a permanent protection of the formed bank slope was installed using a Gabion revetment.
The Gabion revestment is made up of a Gabion Mattress that is filled with the required size boulders on the river bank. After the filling of the unit is complete, the structure is lifted by a 10 T Jib Crane and is loaded on a 200 T capacity barge. Following this, the barge is shifted into the placement location by a tug. The units are finally placed accurately and uniformly into position, without imposing local stress on the mesh at the lifting points.
Currently, after 13 years, the Gabion Mattress installation continues to protect the bank successfully. For more information, please contact us.
For more technical details, please download the Case History.