Reasons for Chennai Rains and Lessons for the City
Chennai witnessed unprecedented rainfall in the month of November and December of 2015. The rains inundated most part of the city, bringing the normal life of the southern metropolis to a grinding halt for more than three days.
There are two angles to look at this episode, one is to find the reasons that caused such a large scale of rainfall and second is to find the cause that triggered huge damage to the city.
Chennai recorded a whopping 1218.6 mm of rainfall in November, almost three times the months average that stands at 407.4 mm. In December, the city received 539 mm of rainfall as against the monthly average of 191 mm that again was almost 3 times more than the normal rainfall in December.
The massive rainfall in Chennai created ripples at the climate change conference in Paris where India’s vulnerability to extreme weather was highlighted.
As such this phenomenon has to be seen from the perspective of global warming and climate change that have begun to show their impact on rainfall and drought pattern in the world.
The ongoing investigation on climate change has revealed that the oft repeat of the El Nino effect is causing drought during the southwest monsoon and triggers rains during northeast monsoon.
One of the reasons for heavy rains in Chennai was the ongoing El Nino weather pattern, which caused dry summers earlier and that extended up to October followed by wetter season in November and December.
It has to be noted that when rest of India experience winters; the East Cost of the country is governed by a separate weather system. As a result of the El Nino effect around this time, parts of West Bengal, Orissa, Andhra and Tamil Nadu receive rains.
This year, the El Nino effect was extremely strong, breaking 18 years old record. This was coupled with unusually-cold sea-surface waters near the Tamil Nadu and Kerala coast. This cold water surface, instead of moving eastward actually moved westward towards Tamil Nadu coast and that caused heaviest rainfall of the century. So Chennai downpour has to be seen as links between the frequency of El Nino and larger warming of the planet. However, El Niño affects was not alone responsible for such heavy rainfall. There was a combination of several other factors.
One being Upper Air Divergence where the lower-level moisture supply becomes high and upper air evacuation of the moisture also gets strong. Its combined effect makes the clouds become very intense. Such coincidence happens rarely but this did happen in case of Chennai, resulting in heavy downpour.
The heaviest rainfall in over a century caused massive flooding across the state, driving thousands from their homes, shutting auto factories and paralysing life in Chennai.
The floods have caused heavy damages to the city as offices were shut down and factories stopped their production. According to Assocham, the financial loss due to record-breaking rainfall in Chennai and several parts of Tamil Nadu may have exceeded Rs 15,000 crore. The insurance claims for damage to property, automobiles and other goods could rise to well over Rs 1,000 crore.
The disaster that occurred in Chennai could have been avoided had there been a better urban planning in place for the city. The main reason for the inundation of the city was the failure of maintaining an effective storm water drainage system.
Chennai's water bodies like the Cooum River, Adyar River and Buckingham Canal, which serve as the main rain water drain for the city, had all seen human encroachments over the years. The creeks and culverts have been blocked due to excessive dumping of the garbage.
Chennai and its neighbourhoods remain unrecognisable as what may have been a tank, lake, canal or river 20 years ago, is today the site of multi-storey residential and industrial structures.
As a result when the Chennai city and its suburbs were being pounded with rainfall exceeding normal limits, the non-functional drainage system catapulted the disaster. Had the government acted earlier to de-silt the water bodies, and spruced up the drainage system, perhaps the areas of the city that faced massive flooding could have avoided the damages.
It’s beyond doubt that the callous approach of the government to address the issues of encroachment and drainage system that aggravated the situation leading to huge damage to the private property.
Now when the normality has been restored the first thing the government should do is to set up a task force to review all on-going construction activity in the city and its suburbs. The authorities should take prompt action against illegal construction that is encroaching upon the tank, lake, canal or river. The CMDA must review of the land-use in accordance with the city’s master development plan.
The next priority of the government should be to maintain an effective storm water drainage system. This may call for investment in the laying of the sewer and sewage system, but such could be efforts in right direction to control future situation.
The devastating floods in Chennai points that fixing infrastructural problems of the metropolises like Chennai is more pressing task than making investments on building futuristic 'smart' cities in the country.
The Union government may consider making the country's metropolis as 'city states.' Since these megapolises have grown many folds in all aspects of urban development they can no more be seen as cities in the traditional sense. As such these cities have to be upgraded to ‘city states’ and such categorization may prioritise infrastructure development and be made more prepared to handle such kinds of future eventualities.
The positive take away from Chennai floods is that the city is well equipped to have waterways transport system as an alternate to surface transport system to ease. The floods have mapped the contours of the waterways of the city and it is left to the government to take a call on its development.
The development of the waterways transport system will decongest the heavy traffic on the city roads and ease its chaos and will definitely make Chennai the smartest city in the country.
Syed Ali Mujtaba