DOT Desk: The approach is cost-effective when applied to small, slow-flowing rivers.
When riverbank erosion—one of Bangladesh’s major natural disasters—displaces thousands of families each year, state-sponsored bamboo and bio-engineering intervention, to mitigate riverbank erosion, provides significant prospects to reduce the destruction, reports the Dhaka Tribune.
Erosion and channel-shifting during the monsoon—more specifically, during the rising and recession stage—results in serious damage to livelihoods in Bangladesh. However, the problems can be reduced by constructing low-cost bamboo structures; with the added advantages of agricultural land reclamation as well as navigational channel development, experts say.
As typical riverbank protection methods with sand-filled mattresses or concrete cubes are expensive, the cost-effective, local technology—using locally-available material and manpower—provides a sustainable way to stem river erosion, they claim.
“Conventionally, spurs, groynes, revetments—or a combination of them—are used to manage and mitigate river erosion and related problems.
However, these structures are too expensive to adapt to the longer reaches of the large-scale alluvial rivers of Bangladesh,” said Moniruzzaman Khan Eusufzai, a senior scientific officer of the River Research Institute (RRI) under the Ministry of Water Resources.
“A 100-meter conventional structure costs Tk40 crore, a 100-meter bamboo structure costs only Tk4 lakhs. Therefore, bamboo bandals [bundles] are important as a low-cost alternative that can be adaptive when necessary; with local socio-economic and environmentally- friendly conditions,” Moniruzzaman told the Dhaka Tribune.
According to RRI research, the key mechanism of bandals is their ability to shift sediment loads, towards the bank line, where water flows at a reduced velocity.
“This bank-shifting is also utilized to divert water flows towards the center line of the channel, to facilitate natural dredging; reducing riverbank erosion,” Moniruzzaman explained adding that: “on the basis of empirically-understood working principles of bandals, they are used to mitigate riverbank erosion and navigation problems.”
After receiving positive results from the protective experimental work— using bamboo structures in different districts over the last couple of years—now the government has been implementing another pilot project on a tributary of Brahmaputra in Rowmari upazilla under Kurigram district.
Financed by the Climate Change Trust Fund (CCTF), the Tk1.6 crore project—consisting of three bamboo structures of 4.9km—began in Bolodmara Kheyaghat, Phuluarchar, and its surrounding area, in mid-October.
The project will be completed in March, 2019.