GARWARE'S EROSION CONTROL MATS STABILIZES SOIL

India has been investing at a prolific rate into infrastructure, urban development, highways, expressways and some ambitious high speed railway lines which are under construction or being planned for next decade.

While the consultancy firms, designers and engineers are involved in developing the most optimistic specifications, DPRs for these developmental projects, our home grown Indian MSMEs and niche market players also play a significant role in addressing few specific challenges where they have expertise in. One such challenge being faced in India or across the globe is erosion of soils and we here are discussing about how to address it in a bio-engineering approach which will be Environmentally Sustainable and compliments UNs Sustainable Development Goals (SDGs) Goal 9, 11, 12 & 13.

Let's understand erosion, its causes and solutions to mitigate associated risks. The erosion of topsoil is one of the major challenges faced in India and across the world. It may be due to natural factors like rainfall, winds, temperature changes, natural weathering or human induced factors like infrastructure developmental activities, construction involving large scale cutting or building high embankments. Factors such as topography, climate, soil type and vegetation cover mainly influence the erosion process. High intensity rainfall, flash floods can trigger erosion process even on some the stable embankment and cutting slopes.

Whatever be the reasons for this erosion it has been having a cascading effect and needs some engineering intervention to control it at the root of the problem. The run-off from rainfall leads to rain cuts on the soil slopes or embankments which in turn lead to failure of highway or railway embankment slopes or the hill cutting zones created for infrastructure or utilities. It's evident that healthy top soil, vegetative cover on ground and erosion are all interrelated.

To deal with this problem, Garware Technical Fibres has been using its unique bio-engineering solution “Garmat Supreme” erosion control mat (ECM) which is specifically designed to solve difficult erosion problems. The ECM is a photodegradable erosion control mat manufactured from long-term double net and 100 percent coconut fibre blanket with a 36-month functional lifespan.

The coconut fibre is equally dispersed over the entire area of the mat, giving the blanket a consistent thickness. Heavyweight photodegradable polypropylene netting with ultraviolet compounds to prevent deterioration and a sufficient mesh opening is used to cover the top and bottom sides of the coir blanket.

During the initial period of vegetation growth, the biodegradable mulch material provides a high level of protection. It also encourages vegetation development by conserving moisture and conditioning the soil. Synthetic nets improve the effectiveness of vegetation in both the short and long term. While the degrading coconut fibres provide the top soils with much needed nutrients, nitrogen content and initial support for vegetation growth.

The application of ECM can be slope as well as channel stabilization. The goal of slope stabilisation is to create an over layer that stabilises the soil, dissipates the effect of raindrops, and supports new plant. Through channel stabilization, it makes the open channels non-erosive. Apart from that it prevents deposition of sedimentation and provides adequate capacity for water management.

Need for vegetative cover

Now that we have learnt about Erosion Control Mat by Garware and its uses, let us try to understand the need for vegetative cover. One of the central uses of having a vegetative cover is that it protects the surface from erosion cause by water as well as wind. The vegetative cover helps to absorb the impact of rain & binds the soil particles. Additionally, it improves the ability of the soil to absorb water, controls velocity of runoff water & helps in removing subsurface water between rainfalls through the process of evapo-transpiration.

The mechanism to manage erosion is to maintain a balance of shear stress and shear strength. A slide happens when the shear stress on any surface of a soil mass exceeds the available shear strength. The total of the components attributable to cohesion and frictional resistance is the shear strength available. Shear strength is essentially a function of the effective normal stress and the effective angle of shearing resistance in materials with little or no cohesiveness. Due to a loss in shear strength and/or a rise in shear stress, a slope that was initially in a state of equilibrium could become unstable. A shallow or deep-seated failure could occur depending on the site conditions.

Garware's Rolled Erosion Control Products

Apart from the temporary (photodegradable) erosion control mats, Garware also offers permanent turf reinforcement mats under its range of rolled erosion control products (RECP). Garware's rolled erosion products have several benefits, including reducing soil erosion, conserving soil moisture, boosting seed germination, protecting seeds and seedlings from heavy rainfall, and allowing for better vegetation settling.

So, what's the difference between temporary and permanent RECPs? Temporary RECPs are employed in areas when natural vegetation is insufficient to provide permanent erosion protection. On the other hand, the permanent RECPs provide a long-term protection against soil erosion where natural vegetation cannot solely sustain expected flow conditions.

GTFL experience

Garmat has been conceptualized and created in line with the vision of GTFL to provide new age solutions for preserving the critical infrastructure while also saving the environment. It has been our aim since the beginning and our endeavours are always focused on that direction. GTFL is a forward-thinking company that is heavily influenced by Japanese Kaizen ideals. This means that the emphasis is on both ongoing enhancement of existing  products and the conceptualization of new ones.

Garware's ECM has a number of significant advantages over traditional biodegradable meshes composed of coir or jute, which are commonly used for erosion prevention. It gives significantly better covering of the surface, resulting in a high level of protection, because it is made up of a continuous mat of fibrous material. This is especially important in instances where the vegetation may take a long time to properly grow. During the early phases of growth, the mat provides protection, which helps to keep the vegetation alive. Ordinary meshes with open openings can only provide a much lower level of security.

GTFL's Geo-synthetics Division currently has a portfolio of offerings for the infrastructure and environmental sectors, including product supply, design and installation services, design and supervision services, and solely specialist design services, as needed. With GARMATSupreme erosion control mat, GTFL is continuing the important work of providing the best solutions through a product that is biodegradable and unique in its own capacity.

- Tiru Kulkarni

President- Geosynthetics Division, Garware Technical Fibers

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