Editorial: Water hazard

NEW DELHI: Cyclone Fengal wreaked havoc across 14 districts of Tamil Nadu, impacted 69 lakh families and 1.5 crore people. In Chennai, which has gone through the travails of inundation time and again during the end of the year, the lessons from each subsequent iteration of the monsoon seems to have been lost on the administration. It has now become an annual affair for citizens in low-lying areas to pack up their valuables, park their automobiles on flyovers, and move to safer terrains in the event of a storm or torrential rains.

As always, the post-mortem of any such episode involves the game of finger-pointing, passing the buck to previous governments, and of course, zeroing in on causes like extreme weather and climate change as the factors responsible for such urban maladies. For people in Chennai, the reality of encroachments on water bodies that are shrinking by the day, leading to excess runoff of water that floods the city, is not something to be wished away.

A report compiled by six organisations including the National Environmental Engineering Research Institute, Nagpur tells us that between 2015 and 2020, the number of waterbodies shrank from 119 to 64, which reduced their size from 101.23 sq km to 67.3 sq km.

This was a consequence of expansions in urban and mixed residential areas, essentially rising urbanisation. The report forecast that by 2025, Chennai might have to contend with just about 62 water bodies encompassing an area of 64.6 sq km. Some of the regions where waterbodies shrank included Tiruvallur, which lost about 98.67% of its resources; Uthukottai lost 94.13%; Avadi 94.25%; Ponneri 70.68%. Obviously, such losses entail a huge blow to building infrastructure — pegged at $ 12.7 bn in 2025.

Those who believe that a surge in rainfall might have something to do with these episodes of waterlogging, might have to eat their words. The researchers said that during the said five year period, there were only minor changes in rainfall patterns, approximately a variation of just 3%.

It is a matter of concern that in spite of the downpour witnessed in Chennai, close to two thirds of the lakes in Chengalpattu and Kanchipuram are yet to be filled. According to farmers in the region, encroachments in the catchment zones as well as the canals leading to the waterbodies have choked the flow of water, leading to such dismal spells of replenishment. The Chembarambakkam lake, which is the source of drinking water for Chennai has a full capacity of 3.64 tmcft, while it has been filled to a level of 2.79 tmcft.

There are as many as 909 lakes controlled by the water resource departments in the two districts; however, just about 309 lakes had reached their full capacity by Monday.

There’s a laundry list of things we need to get right, so that we are better placed to deal with the uncertainties posed by a warming planet. Experts have sought for the rejuvenation of waterbodies to restore their full retention capacity.

Apart from the desilting of canals for the optimum flow of water to the lakes and expediting work on stormwater drains, there is a need to adopt green infrastructure models, which include stormwater harvesting, permeable pavements and rain gardens. Sustainable urban planning should be the order of the day, with emphasis on improved drainage and early warning systems to mitigate the threat of adverse weather events.