04 Feb 2021: From droughts to floods: Chennai's water problem needs immediate solving
Chennai, India's sixth-largest city and home to 11 million people, witnessed its worst floods in 2015. Four years later, the city's taps infamously ran dry in the summer of 2019.
The southeastern city has now become a case study, highlighting the potential consequences of industrialization, urbanization, and extreme weather conditions.
Experts now warn that these flood-drought cycles could only become more intense.
Context: 3 rivers flowing through Chennai are all polluted
Chennai is a low plain city with a natural ecosystem comprising three rivers, five wetlands, and six forest areas. However, the three rivers are all heavily polluted.
As a trading link, the city boomed and its rapid urbanization paved the way for more houses and greater industrialization, albeit with poor planning.
The city also gets an average 1,400mm of rainfall a year.
Fact: Cyclones in Bay of Bengal worsen flood problem
Further, cyclones in the Bay of Bengal cause water from the sewage-filled rivers to flood Chennai's streets. The rainfall is also uneven—90% of it falling during the monsoon season in November and December. When rains fail, Chennai has to rely on huge desalination plants.
Reason: As Chennai grew, its lakes and ponds disappeared
Between 1893 and 2017, Chennai's water bodies shrank from 12.6 square kilometers to about 3.2 square kilometers, Bloomberg reported citing researchers at Chennai's Anna University.
Most of that loss occurred in the past few decades. Notably, Chennai's IT corridor was constructed in 2008 on 230 square kilometers of marshland.
It is estimated that around 60% of Chennai's groundwater will be critically degraded by 2030.
Fact: 'Politics, business have visions too short-sighted'
"The two most powerful agents of change—politics and business—have visions that are too short-sighted," Nityanand Jayaraman, a writer and environmental activist who lives in Chennai, told Bloomberg, "Unless that changes, we are doomed."
2015 floods: Chennai faced worst floods in century in 2015
The lack of places available to hold precipitation, flooding increased, and in 2015, Chennai faced the worst deluge in a century.
In a single day, the city received 494mm of rain. Over 400 people were killed and 1.8 million were displaced.
Floodwaters reached as high as the second floor of some buildings in the IT corridor.
Day Zero: In 2019, Chennai hit Day Zero
In the summer of 2019, Chennai hit Day Zero: the day when a city's taps dry out.
The government was forced to truck in 10 million liters of water a day.
Chaotic scenes unfolded as people lined up to fill water containers for hours.
Reports had emerged of tankers being hijacked and violence also erupted in some neighborhoods.
Fact: Chennai saw wettest January this year
Chennai had its wettest January in decades this year, receiving more than 10 times the normal rainfall for the month. "Such heavy rainfall was not normal when my parents and grandparents were young," Arun Krishnamurthy—founder of Chennai based non-profit Environmentalist Foundation of India—told Bloomberg.
Future: Rising temperatures, lesser rainfall estimated in future
Tamil Nadu has predicted that the average annual temperature will rise 3.1°C by 2100 from 1970-2000 levels.
Annual rainfall is estimated to fall by 9%. Precipitation during the June-September southwest monsoon—which feeds reservoirs and irrigates crops—will notably reduce.
Further, the flood-prone cyclone season in the winter is likely to become more intense.
This would result in worse floods and droughts.
Plan: Greater Chennai Corporation now supporting 'City of 1,000 Tanks' initiative
The government's efforts to replenish groundwater have failed to exceed the pace at which the water is being extracted.
The Greater Chennai Corporation is now supporting an initiative called City of 1,000 Tanks to restore some temple tanks and build hundreds of new ones.
Planned green slopes will absorb and filter heavy rains, recharge the groundwater, and store water for use during dry months.
Plan: Project should take 5 years to have an impact
Sudheendra NK—director of Madras Terrace Architectural Works, which is involved in the project—told Bloomberg, "When a critical mass of people take up all this then a significant difference will be noticed..."
Sudheendra said the project should take up to five years to have an impact. However, with Chennai adding roughly 2.5 lakh people every year, it's a race against time.