Shoring Up Sustainability : TechFab India Geotextile Bags protects the Banks of the Brahmaputra River in Tinsukia, Assam

Floods are among the most frequent natural calamities in India. India has witnessed several riverine floods historically that have affected millions of people, caused loss of lives, and damaged infrastructure and agriculture. An increasing number of flood events in recent times has heightened the importance of flood protection works and the raising of embankments in urban and rural plains. The high tractive shear stress of flowing water and the migration of soil particles lead to the progressive erosion of river banks. The damage to the natural banks reduces the bund height and may let the floodwater spill out of its banks, causing floods.

The river Brahmaputra has been the lifeline of northeastern Indian states for ages. This mighty river runs for 2880 km through China, India, and Bangladesh. Every year, the northeastern state of Assam experiences huge losses due to devastating floods in the river Brahmaputra. Tinsukia Town, located in the upper reaches of the Brahmaputra River in the state of Assam, experiences significant damage due to the floods during the monsoon season. The high intensity of floods in the Brahmaputra River and the steep topography of the region make the problem more complex and severe.

To provide a safeguard against the frequent floods in the region, the banks of the river Brahmaputra near Tinsukia needed protection at a few stretches while providing sustainable anti-erosion measures.

Solution
In river training projects, the conventional use of large boulders poses significant challenges. The mobilisation of substantial quantities within a limited contract period proves difficult and expensive. Furthermore, the extraction of such vast amounts of stones adversely impacts environmental equilibrium. The transportation and handling of these materials to the worksite necessitate heavy machinery, adding logistical complexities.

TechFab India’s innovative approach offers a compelling alternative. Geotextile bags, filled with locally available sand, emerge as a cost-effective solution, particularly in soil erosion control. The work was carried out on the left bank of the Brahmaputra River for a total length of approximately 700m, where the river bank was dressed to a slope inclination of 2H:1V for the maximum protected bank height of approximately 10m.

The geotextile bags (1.03 x 0.70 m in size), made of nonwoven polypropylene 400 gsm, have been selected for river bank and bed protection. These structures, permeable in nature, not only prove economical but also effectively control sedimentation. By utilising locally sourced materials, the project ensures sustainability while minimising the environmental footprint associated with conventional methods. TechFab India’s geotextile bags solution stands out as an efficient, eco-friendly, and economically viable choice for river bank protection in Tinsukia, Assam.

Installation of TechFab geotextile bags
The installation of geotextile bags followed a specific sequence. Initially, the area was set out according to the drawings. Geotextile bags and the necessary filling material were mobilised to the project site.
The excavated topsoil was then disposed of by tippers to a suitable distance from the bank side to reduce the overburden of the bank. Slope formation was conducted with necessary ramming to remove any undulations, correcting it to the desired slope before laying the nonwoven geotextile.

A layer of nonwoven geotextile was laid along the desired slope. This geotextile acts as a separator and filter at the interface of the embankment soil and protection works, helping to release pore water pressure by allowing the passage of water and trapping soil particles. Following this, the geotextile bags were filled on-site with locally available sand, adhering to the standard technical specifications of the project. Once filled, the geotextile bags were measured to confirm they met the desired weight and thickness specifications.

The bags were stitched using high-strength polypropylene multifilament (PPMF) yarns as per the standard technical specifications. For convenience, the bags were stored in batches or suitable multiples based on the available space at the site. The laying of geotextile bags for the launching apron was carried out when the river was in a lean flow condition or with the help of small boats to complete the activity on time. The placement of bags was supervised by the site in charge, with the work inspected periodically by the Authority.

Conclusion
The project successfully addressed erosion in Tinsukia by using TechFab Geotextile Bags, proving the effectiveness of innovative solutions in tough environments.

TechFab (India) Industries Ltd.
Web : www.techfabindia.com