It helps to have permeable paving

June 15, 2013 12:00 am | Updated May 25, 2017 05:36 pm IST

Keep the dust away and let water pecolate down, writes BIJU GOVIND.

In conservation of water, every drop counts. So leaving your front yard unpaved to let rainwater seep into the ground will be a good idea. But if pave you must, do it with the help of technology. It is a brilliant idea to keep the dust and dirt down but let the water percolate down.

Even after a particularly gruelling summer, much of the rainwater that the monsoon clouds send the way of the State still flows straight into the sea, without recharging groundwater. Rain and drought thus alternate in the State. To break the cycle, old habits such as concreting courtyards should die.

Employing the technology called permeable paving for parking areas, driveways, sidewalks and areas around buildings is one small way of conservation, M.V.L.R. Anjaneyulu, Professor, Department of Civil Engineering, National Institute of Technology, Calicut (NIT-C), says.

Usually, pavements are constructed using impervious materials such as concrete and a bituminous mix. So the rainwater runs off, leaving a negative impact on the environment by cutting off the natural groundwater recharge. Besides, concrete raises heat in cities, prevents growing of trees and destroys aquatic habitats.

Hence, engineers and architects are turning to the new technology known as permeable paving. “Unlike conventional materials and methods, permeable paving provides networks of void spaces, which allow water and air to pass through them. It is beneficial to the environment, and as a bonus, beautiful urban landscapes can be created from it,” Prof. Anjaneyulu says.

Despite the benefits, porous paving materials are still relatively unknown in urban design and construction, partly because engineers are yet to catch up with the technology.

The public is unaware that permeable paving is a viable alternative to concreting or tiling, he says.

Grass pavers

One of the permeable paving techniques is use of grass pavers in open cell or open joint types. The Indian Institute of Technology, Chennai, has adopted one such on its campus. “We have plans to do in NIT-C also,” he says.

Porous paving reduces pollution and improve urban hydrology by allowing water to seep into the ground. It lets pollutants seep into the soil, where they can degrade naturally instead of contaminating water supplies. The risk of flash floods comes down with such paving.

Typically, built-up areas are two degrees to eight degrees hotter than the surrounding countryside. “About 90 per cent of this heat increase is due to buildings and pavements, which absorb and store solar heat. Emissions from vehicles, buildings and factories make up the remaining one per cent to 10 per cent.

One of the solutions to reduce heat is use of porous pavements as they allow trees to grow,” Prof. Anjaneyulu says.

Porous pavements include grass or other vegetation in their structure, lending a significant cooling effect on the environment around them. These pavements may be cooler than asphalted roads.

Grass pavers merge natural environmental processes with urban infrastructure, developing beautiful urban spaces.

Porous pavements have been used in creative ways to create parking lots resembling parks, forested amphitheatres or elegant walks. Their ability to combine functionality and aesthetics make porous pavements a useful tool for designing urban landscapes, he says.

Prof. Anjaneyulu says the practice of concreting pavements or laying interlocking tiles increases the chances of pollution of waterbodies. Rainwater usually washes pollutants from the atmosphere, vehicles and animal waste into surrounding water supplies. Since impervious pavements cover large areas, these have become the most significant generators of urban runoff and pollution.

Another problem with impervious pavements is that they prevent stormwater from replenishing streams and underground aquifers. Run-off from storms sweeps through roads causing traffic blocks.

Detention basins are traditionally used to prevent flooding. However,s these are not a perfect solution and do nothing to improve water quality or replenish groundwater, he says.

Studies show that groundwater depletion is posing a severe threat with each passing year.

In the State, summer troubles begin in March and extend till the onset of the monsoon in June. Even rivers go dry.

Permeable paving provides networks of void spaces, which allow water and air to pass through them.


The new technology is one small way of conservation


Porous paving allows trees to grow with no hindrance.


It reduces pollution and improves urban hydrology.

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