Sustainable measures for floods and landslides in north-eastern India

Vikramjiet Roy

To prevent hazards, India must develop a green economy that places sustainable building techniques at the centre of its growth strategy.

It is necessary that India moves quickly towards building sustainable infrastructure.

05th July 2022, Guwahati: Excessive rains have wreaked havoc, and landslides have hindered road, highway, and rail access to the north-eastern areas. Due to factors like construction practices in India's north-eastern region, pre-monsoon rains have created a series of geohazards such as landslides and flash floods. The flooding situation in Guwahati has drastically deteriorated into a more severe condition during the last ten years, as is widely documented.

Due to the unplanned growth of the city and the accompanying increase in population, there has been significant encroachment on wetland and low-lying areas, hills etc. The forest cover has shrunk. The loss of wetland and deforested slopes results in floods and waterlogging. Furthermore, the soil carried by rainfall from the city's flooded hills finds its way into the sewers quickly filling them up. Additionally, considering the lack of side drains on roadways and the nearly non-existent gradient and storm discharge conveyance, the wetland areas cannot manage the excessive downpour in the city.

These disasters affect not only people and communities but also economies, governments and transportation facilities on which we rely. Any reaction to floods and catastrophes must be swift and effective to restore the natural state of the affected area, contain the damage, and allow people to resume their lives. Removing water with a suitable drainage path can provide long-term improvements to that soil and solve various associated problems. The modern solution is to use a drainage geo-composite like MacDrain® to drain fluids underground from one place to another. Geotextiles attached to the drainage core of MacDrain on one or both sides stop soils from being washed out and, as a result, potentially avoid clogging the drainage core and collection pipes. They are designed to replace traditional drainage materials such as gravel and sands. Moreover, extreme rainfall causes a washout of structures and triggers landslides and floods. Deploying barriers for flood protection, raising embankments and strengthening support for temporary works are a few steps that can help mitigate the adverse effect.

Systems like FlexMac® DT can be used for such situations which consist of a multi-cellular structure made of hexagonal double twisted wire mesh. The mesh is reinforced with vertical steel rods and internally lined with a non-woven geotextile sleeve.

Also, 100 per cent vegetation cover across geographies is challenging to achieve on hilly terrains. It is also highly unsuccessful as vegetation may not survive and provide enough strength to the soil for several factors. For sustainable infrastructure development, soil conservation using new-age engineering technologies like hydroseeding, and the use of mattresses can be adopted. Mattresses are filled with stones at the project site to form flexible, permeable, monolithic structures such as riverbank protection and channel linings for erosion control projects. Also, synthetic or natural mats combined with hydroseeding are used to cover large slopes promoting vegetation growth.

Mr Vikramjiet Roy, Managing Director, Maccaferri India, commented, "India needs to build a green economy with sustainable construction practices at the core of its developmental plan to avoid such hazards. We all know that construction is an essential prerequisite to development. Buildings, roads, dams, ports, railways, industrial parks, special economic zones, and every other infrastructural development cannot be possible without construction practices. Now, India must swiftly shift toward sustainable infrastructure development to meet the infrastructure demands of an ever-growing population while also limiting its effect on the environment."

Maccaferri recently supplied specialized flexible wire meshes such as High Energy Absorption (HEA) Panel and Steelgrid® MO as components of secured drapery for rockfall protection. These wire meshes helped facilitate easy and quick installation on this challenging terrain along with Self Drilling Anchors (SDA) as surface anchors in January 2021, when Northeast Frontier Railway (NFR) in India was constructing a new railway line connecting the Garo Hills in Meghalaya with Assam. Maccaferri, with this project aimed to ensure an overall sustainable project, which entails environmental sensitivity, local ecology, economics, cultural sustenance, future possibilities and is financially feasible.