Lifting Chennai out of drought

Chennai faced a devastating flood in 2015 that killed hundreds of people and displaced many more. Today, the southern Indian city’s four main reservoirs are virtually dry. This crisis is not only due to lack of water. Lack of proper management exacerbates dry conditions in Chennai and many other cities around the world.

Chennai gets its water from four main reservoirs—Puzhal, Cholavaram, Chembarambakkam and Poondi. Today, the first three have completely dried up and Poondi has very little water left. With the northeast monsoon still months away, relief is unlikely to come soon.

While last year’s poor monsoon season contributed to the current crisis, Chennai’s water scarcity has increased in recent decades, driven largely by unplanned urbanisation. Chennai’s population grew from about 500,000 to more than 11 million over the last century. According to WRI’s Aqueduct Water Risk Atlas, Chennai faces extremely high baseline water stress, meaning that on average more than 80% of available water supply is used up every year by agriculture, industries and consumers. At the same time, the water that is available is becoming increasingly polluted. Dumping untreated sewage into lakes is common practice in Chennai. These pollutants also seep into the soil and affect groundwater, further worsening the city’s water security.

What can be done?

Many have proposed ideas such as bringing water from other watersheds or investing in desalination plants to provide water to increasingly water-stressed Chennai. But bringing water from distant watersheds such as Cauvery or Krishna wouldn’t help the city in the long run, as these watersheds are also facing water-scarcity issues; Krishna, for example, didn’t provide relief for the city this year during the crisis. Desalination plants could address some of the concerns, but they are very costly and consume a lot of energy. Chennai’s government is in the throes of a crisis — a difficult situation in which immediate action must be taken to sustain residents until the monsoon comes. The city should also think about taking steps to help avert a similar situation in the future:

Harvest rainwater: The easiest technique for the city is to better enforce the existing rule on rainwater harvesting in buildings. Rapid urbanisation has increased the area covered by concrete, preventing groundwater recharge and rainwater absorption. Recharge points such as green spaces and wetlands need to be created across the city. These recharge points would allow the ground to absorb stagnant water on roads and increase groundwater levels. Corporates could also fund these solutions as part of their corporate social responsibility programmes.

Reuse wastewater: The Cooum and Adyar rivers carry a huge amount of sewage into the sea every day. Multiple lakes across the city have also been affected by sewage dumping. Small sewage treatment plants combined with apartment-level treatment systems could help treat the sewage without using up more space. The treated sewage water could be reused for non-potable purposes (running ventilation, AC systems, flushing toilets and landscaping) across the city while improving water quality overall.

Conserve lakes and flood plains: Chennai’s master plan must prioritise protection of lakes and associated flood plains. Flood plains are the biggest recharge points, and they also help prevent floods. Rapid construction over flood plains has made Chennai vulnerable to both floods and drought. The Chennai Metropolitan Development Authority should immediately take steps to stop construction over flood plains.

Open data: Part of the problem is that the government does not provide open and transparent data on water resources and uses, such as the extent of water pipes and how much water flows through them every day. More research and analysis could be done with open data, which could lead to better solutions.

Improve efficiency: Agriculture is the biggest water consumer in India and in Chennai. Any improvement in irrigation efficiency would increase water resources. It would be irrational to expect farmers, most of whom are small-scale, to implement high-cost irrigation systems. The government should explore and implement new financial models that would allow investment in and improvement of rural irrigation systems.

‘Day Zero’ (when all reservoirs go dry) is almost upon the city. It is imperative to start implementing sustainable solutions with a focus on integrated water resource management. Chennai, and other cities like it, could be water-secure again, but only if positive action begins now.

(Raj Bhagat Palanichamy is an Earth Observation specialist working with World Resources Institute-India in the fields of Urban Development and Water Resources)

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Printable version | Jul 19, 2021 2:30:25 PM |

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