Hello,
@Barty! Welcome to the forum!
The average annual rainfall of Chennai is 140 cm or 55 in. The months of mid-October to mid-December are the most rainy ones. In 2005, the highest annual rainfall was recorded here at about 257 cm or 101 in. Chennai does receive moderate to heavy rainfall each year.
However, just last year during the month of December, Chennai experienced its worst rainfall yet. Airport shutdown, train shutdown, factory shutdown and emergency evacuation for residents were done. For the most part, the storm at that time was exceptionally strong. The rainfall at that time exceeded the normal limits about three times more.
During the month of November then, Chennai received 1,218 mm, again, this was over 3 times than normal. The normal monthly rainfall was at 404 mm. On the first day December last year, 344 mm of rainfall was recorded. The city's main reserves, rivers and tanks were overflowing at this time and also contributed to the floods.
Aside from the airport shutting down, electricity was also shut down. Businesses were forced to shut down for 21 days resulting in an economic crisis as well. Worst part though is that about 65 people died in this tragic disaster.
The storm itself was strong but we cannot deny that there has been some failures on the part of the government, and maybe the people as well. This incident lead to the discovery of the poor infrastructures in the city. The city has been a major business hub and so there was an increase in the people and vehicles. However, not many infrastructures were built to handle them.
The reservoirs weren't planned that well, as they weren't able to handle the huge gush of water that time. Drainage systems were filled with silt and garbage as well. Perhaps, to better avoid this incident in the future, the government and the people need to work together. Chennai is fast becoming an urban city and certain measures has to be done to prevent this disaster from happening in the future.
As I've said, the people also has some part in it. Low lying areas aren't meant to be lived in, yet real estate constructions are done there. Some even with multiple storeys. And if the government says that the area is not suitable for living, still, people stand their ground. Maybe because their line of work is still in the city. So we go back to the government to provide some forms of occupations for people in the rural areas.
There are many reasons as to why the flooding and raining occurred. Generally, rain is a part of the life of the residents in Chennai. The flooding though isn't that normal. And that's one thing that can be fixed by both the people and the government.
I hope this helps.