Urban floods: A new reality that planners must budget for
The Chennai floods story is eerily similar to the one in Mumbai 10 years ago or the one in Srinagar last yearmumbai Updated: Dec 08, 2015 21:50 IST
Urban flooding has not received the attention it deserves in a country with rapid urbanisation. Heavy rain and flash floods inundating cities, sometimes with intensity not recorded in a century, is now an annual feature. The Chennai floods story is eerily similar to the one in Mumbai 10 years ago or the one in Srinagar last year.
The Mumbai flood of 2005 was considered as a wake-up call for official agencies and citizens. A decade later, Mumbaiites may know that the Mithi is actually a river, not a sewer drain; that the city has six rivers that empty out into the Arabian Sea; there is an early warning system in place and a disaster management control room; there are automatic rain gauges installed across the city and contour maps prepared.
But are we certain that we would be safer, better protected and more informed if the city were to again receive rainfall as it did on that fateful day in July 2005, a record 944mm in 24 hours? Going by the status update we receive from the government and media every July, it appears that Mumbai could be rendered just as helpless and unsafe as it was then. Has Srinagar learned its lessons, will Chennai learn? As long as urban floods are defined as these once-in-a-century events, the lessons will be missed.
The extremely intense floods such as Mumbai 2005 and Chennai this year may be unusual phenomena brought on by a rare combination of meteorological, hydrological and human factors, but urban flooding is more common than we realise it to be. Indeed, repeated incidences of urban floods in the last decade are as follows: Mumbai (nine times), Chennai (six times), Hyderabad (five times), Ahmedabad (seven times), Kolkata (five times), Bengaluru (four times) and Surat (thrice). This does not include Delhi, Srinagar and other metros, which have experienced floods fewer times.
That urban flooding is significantly different from rural flooding, calls for an altered flood management approach, and its management must be dovetailed into urban planning itself were recognised five years ago in the exhaustive guidelines developed, after years of consultations with multiple central and state agencies, by the National Disaster Management Authority (NDMA). It reaffirmed the causes of urban flooding: Rampant land-use changes, unregulated construction without accounting for natural water flows (such as the airports in Mumbai and Chennai), encroachments, sealing off natural drainage systems such as rivers and lakes, ageing storm water drains, improper waste disposal, and ineffective warning and information systems.
The guidelines have remained on paper. The separate nodal unit that the NDMA had recommended to be set up within the Ministry of Urban Development to deal with urban floods is not yet a reality. While the ministry goes about making smart cities with a ferocious energy, it misses or overlooks the need to account for urban flooding in a methodical manner, and get states and urban planning agencies excited about it.
The relationship between urban flooding and human encroachments on natural eco-systems is now too obvious. Mumbai has nearly 60% more built-up land today than it did 90 years ago, its river systems are seen more clearly on a map than in reality, and its lakes are smaller than ever. The story of urban development is similar in Srinagar, Chennai, Hyderabad, Guwahati and other cities that witnessed frequent urban floods in the last decade.
To continue to rapidly urbanise and expand our cities without factoring in urban flooding now would be a foolish thing to do indeed. With climate change phenomenon making urban floods the new normal, urban development plans would have to include ways to prevent such floods as well as create flood management systems. There is little evidence of this in Mumbai’s planning. The 2005 flood is treated as a one-off episode. Nothing could be more disastrous.