Heavy rainfall on Tuesday inundated parts of Tamil Nadu, including Chennai, and Puducherry, severely affecting daily life – yet again. Heavy to very heavy rainfall for Chennai, Tiruvallur, Kancheepuram, and neighbouring Puducherry is forecasted for Wednesday. The disruption from the inclement weather event is to the extent that a holiday was declaredon Tuesday for educational institutions in these districts and in Puducherry. Apart from water-logging in several areas, flight operations also took a hit – a flight from Colombo even made a retreat. Chembarambakkam lake is a key reservoir that provides drinking water to the city. The possibility of increasing discharge of excess water from this lake into Adyar river has made Chennai Collector E Sundaravalli announce for evacuation along the banks of Adyar river so people could move to safer areas. The suburban train services operating between Chennai Beach and Tambaram has also been hit due to severe rains in the cities. Puducherry was pounded by rains since Monday night and recorded 15.2 cm rain, ending on 08.30 on Tuesday. Chennai is a place of brutal summers with a scarcity of water, but when it rains, the coastal metropolis of over four million people often finds itself inundated by too much of it. And this year, the rains have been particularly deadly, killing at least 79 people across Tamil Nadu. The Army and the Air Force are at service to rescue marooned residents. Beneath all these current events, it needs to be understood that none of this is entirely unexpected. Some reasons for this situation are entirely the fault of the city’s administration – rapid urbanisation, destruction of critical wetlands, inadequate infrastructure are few to blame. Additionally, Chennai’s geography is such to precipitate the situation: the city is spread across a low-lying area and is flat like a pancake. The average elevation of the city is only about 6.7 metres above mean sea level, with many neighbourhoods actually at sea level. This makes drainage a challenge even under regular circumstances. Apart from the Cooum and Adyar rivers, Chennai’s periphery once hosted a massive wetland which provided a natural flood control barrier in the past. The Cooum has now been reduced to a massive, stinking sewer that snakes through the heart of the city, heaped with the waste generated by the metropolis. Rampant encroachment and urbanisation in its upstream reaches have sapped the ability of the Adayar river to carry flood water. Another key waterway, the Buckingham Canal, is also choked with silt and sewage. So, when Chennai floods, there aren’t enough unobstructed channels for the water to get out. And a rapidly expanding city has decimated the critical Pallikaranai marsh, which acted as a natural flood sink when the rains overwhelmed Chennai. The government has already spent large sums of money to clear up Chennai’s rivers and resuscitate its sewage infrastructure. But most of it is just good money gone down the drain.