Erosion Mitigation
Bamboo made gabion protecting vetiver grass to root
As structural mitigation against erosion and floods bamboo cages can be filled with locally available stones to protect land slide prone slopes and riversides. These gabions are very easy to produce by local people who live in bamboo regions, but require a lot more than just filling them with stones.
The main hurdle is to convince people that bamboo can actually serve for the time vetiver grass need to root three meters into the river bank.
The community has to be sufficiently motivated to treat the bamboo against insects, maintain the structures on a periodic schedule and plant the rooting grass.
Testing the strength of a bamboo gabion
To build the gabions, slats are cut in one bamboo pole leaving both ends intact. Then the entire pole is manually compressed from both ends and a spool shaped basket is automatically created. Bracing slats are then tied in with steel wire. The large number of these connections makes the structure surprisingly strong.
The spool formed bamboo gabion inspected
Windows can be cut anywhere to fill the gabion with stones and then closed again with more wiring.
Although some borax and waste motor oil treatment is recommended the gabions will not last forever. Therefore the long term solution is the planting of grass with deep-growing roots, such as Vetiver. The community has to be sufficiently motivated to treat the bamboo against insects, maintain the structures on a periodic schedule and plant the rooting grass.
Retaining gabions with rebar and bamboo anchor claw
In addition to the gabions there is also a system of retainers made from reinforcement bars and bamboo anchor claws. After drilling horizontal holes in the river bank with an auger, bamboo claws are inserted to retain the gabions. (see PDFs further on) All these prerequisites have to be comprised; otherwise a mitigation project like this will backfire. Bamboo is not known as a permanent construction material to local people, and the poor man's stigma is the worst problem to fight.
For more details:
Construction gabions....Mitigation_engineering: PowerPoint, Baguio, Philippines 2010....