Chennai floods

@Ashish Rai: Chennai flood is not about rainwater harvesting at all. Late CM Jayalalitha made it mandatory in all buildings. Most old constructions added RWH and new complexes integrate it in their planning. The ground gets saturated very quickly and stops absorbing any more water. This year, Chennai received more rain in the Jun-Sep period and ground water level almost reached the surface in many localities. The actual problem is something quite different. I will answer in some detail to those unfamiliar with Chennai and its unique issues. 1. Chennai is a coastal city and is almost flat. Most areas are just a few meters above sea level. Natural draining has always been a problem. 2. Historically, Chennai has been built by filling up existing lakes and so most core city areas had lakes bearing their names (Egmore lake, Nungambakkam lake and so on). There are lake areas and lake view roads in many localities where no lakes can be seen. 3. Chennai receives its rain mostly during November-December (Northeast monsoon) unlike the rest of the country. Though the average annual rainfall is less compared to the other cities (which receive rain from SW monsoon), the intensity can be quite high because of the number of rainy days being less. In this cyclone, Chennai received a little over 500 mm of rain in a 48-hour span (Dec 3 AN to Dec 5 FN). This is almost 40% of the annual average rainfall. Also, during a cyclone, the sea level temporarily goes up. This caused the famed Marina Beach of Chennai to get submerged and become an extension of the sea with no sands visible anywhere. Also, existing water ways (Chennai has 3 minor rivers flowing within the city) get backed up by rising seawater and prevent draining. 4. The population pressure due to internal migration has resulted in a very unplanned expansion of Chennai. Since many current DMK ministers own real estate companies through benamis (not unlike the Italian mafia), they use their political power to occupy lakes, flood plains and natural run-off channels and convert whole areas of chennai into construction space. When you build houses over lakes, you should not complain when lakes take over your houses after a heavy rain-spell. In their greed for profits by real estate politicians and desperation for affordable housing by the common man, all ethics and guiding principles for construction (based on maximum flood level) have just been ignored. 5. The present government, known for their corrupt practices in the state (and when they are a part of the erstwhile central government too) have no care or sympathy for the general populace. That is why we saw the constituency of the chief minister (very aptly called Kolathur-Kulam means' lake' in Tamil) got flooded waist-deep after the first spell of cyclone driven rain). 6. In most cases flooding was a result of lakes getting filled and overflowing through breaches (or the floodgates being opened in the main water reservoirs). Since most natural drain channels have been filled by apartments, water straightaway entered these complexes and after more than a week of rain, their basements full of expensive cars still remain flooded. These problems cannot be solved with patchwork solutions. They call for a systemic change, which I do not see coming anytime soon. After a couple of weeks of government-bashing, people will go back to their routine and forget that it ever happened. more  

No rainwater harvesting. Nearly 90 per cent of the rainwater received by the State is wasted in the Bay of Bengal. https://www.dailypioneer.com/2023/columnists/chennai-bears-the-brunt-of-cyclone-michaung.html#vuukle more  

The oil spill crisis. https://epaper.hindustantimes.com/Home/ShareImage?Pictureid=1312f1e827f0 more  

Some things require rescuing, some a hands-off approach. more  

Fully agree. Indiscriminate construction without any thought on the environmental impact. See attachment. Citizens are egually responsible as they create the demand. more