Guwahati: To Feel the Heat…

ENVIRONMENT MATTERS

Economic development is vital for a country, but mitigating the adverse impact of UHIs is equally important. To this end, several methods are being tried and many more can be tried. Using greener roof tops, using light coloured concrete, making road surfaces grayish and even pinkish (as some places in US have done as these colours are 50 percent better than black) are a few commonsense methods. 

Recently a bulletin from the Indian Meteorological Department (IMD) stating that Guwahati may witness a drop in its sweltering temperatures had brought sighs of relief to many who inhabit this fast-growing city of the North Eastern region.

Guwahati has seen an unprecedented increase in its average temperature in the last couple of months. On August 5th, the city recorded the highest ever (in history) temperature for the month of August. This was a scorching 38.6 degree Celsius, which is a 9 degree jump from the average temperature of 29 degree Celsius recorded just five years ago.

The sun had seemed relentless and the much anticipated rain, which had just months ago caused havoc throughout Assam triggering colossal floods and breaching embankments had almost become like an 'elusive object of desire'.

It is actually difficult to juxtapose the images of deluge (a recurring feature of Guwahati every time it rains) with that of the tormenting sun, blazing its wrath on the teeming multitudes of people.

Monsoon rains had eluded Assam since the first week of July. While the state saw 61 percent excess rain in June, rains were at a 39 percent deficit in July and also August. During the pre-monsoon period, Assam witnessed 760.7mm rainfall as against the normal 543.6mm.

The extremities in weather condition, is a warning or rather an announcement that climate change is real and is knocking at our doors. Unless we understand the gravity of the situation, we are heading towards an existential disaster.

Guwahati, which has been fashioned as a vibrant metropolis is now literally facing the heat. Unplanned concrete development, reduction of green cover, filling up of wetlands and large scale concentration of people has turned Guwahati into (according to environmental experts) an Urban Heat Island (UHI). This is essentially a condition where an urban area is relatively warmer than the suburbs.

This phenomenon can be attributed to the fact that the construction materials used in cities (for pavements, roads and roofs) such as concrete, asphalt (tar) and bricks have a higher heat retaining capacity and thermal conductivity. The urban geometry of cities (dimension and spacing of buildings within the city) also plays a vital role in compounding the heat load of the city.

Most of the cities, including Guwahati have areas that can be categorized as Urban Canyon (a narrow street lined by tall buildings).These areas experience greater heating and form a source point for UHI.

As cities develop, marshy soil is often used for constructions and rivers and wetlands are encroached upon. The prime wetlands of Guwahati are shrinking at an alarming rate. These are natural rainwater reservoirs and play a key role in sustaining the ecology. The beels or wetlands have been ravaged by construction, soil fill up and dumping of garbage. Incidentally, Deeporbeel has been drastically reduced through encroachment from 40 sq kms about 50 years ago to just 4 sq kms now.

With the loss of the wetlands, the city has lost its natural ways of regulating temperature, its flood channels and also its ability to transmit water into underground water reservoirs. This has also led to higher energy expenses as people now contend with hotter summers and colder winters. The city becomes vulnerable to floods and the water table fall slower and lower.

UHI decreases air quality and increases colonization of species that like warm temperatures, such as lizards and geckos. In addition, cities tend to experience heat waves which affect human and animal health leading to heat cramps, sleep deprivation and increased mortality rate.

Economic development is vital for a country, but mitigating the adverse impact of UHIs is equally important. To this end, several methods are being tried and many more can be tried. Using greener rooftops, using light coloured concrete, making road surfaces grayish and even pinkish (as some places in US have done as these colours are 50 percent better than black) are a few commonsense methods.

Assam Type houses, a unique civil engineering style of Assam that uses indigenous knowledge and local construction materials are an amazing testimony of ecofriendly and sustainable housing. These houses are also energy efficient and climate resilient. Beside their aesthetic value, these cottages, bungalows and mansions can be a systemic tradition-based instrument to reduce UHI.

There is however no substitute to increasing green cover while addressing the challenges of climate change. Trees clean the surrounding air by absorbing pollutant gases (NXOy, O3, NH3, SO2 and others) and cool the city and the streets. Trees also conserve energy (cutting air-conditioning costs by 50%) and save water and help to prevent water pollution. Moreover, trees help to prevent soil erosion; protect people from UV light and mask concrete walls thus muffling sounds from streets and highways.

Guwahati is experiencing one of the largest urban growth spurts in its history. It is still a city in transition. This presents a unique opportunity to look at urban planning and development through a long term strategic lens. The right economic, environmental and social impacts should be envisioned. Building informed consensus about future growth and development is crucial. Only progress of this kind will help to build a vibrant, inclusive and livable Guwahati.

By: Emon NC

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