williams wrote:Govt need to build 4 or 5 storm water channels around the city. The channels can eventually drain into the sea. It is a simple common sense work city PWD can undertake to stop this kind of disaster in future. That said, it is great to see the people working together calmly to help each other.
It's not so simple. True, the natural channels are blocked by silt, encroachments and etc., and lakes built up over, or shrunk in size, leading to less water retention capacity. But that's not all. There have been storm water drains built in various places to alleviate flooding, and
they have worked to an extent. For instance, Velachery has a 6 feet wide drain to take excess water away from the locality, into the Pallikaranai marsh. This has helped to an extent in the past few years. This past month, though, this drain has been draining to full capacity, but
the quantum of water is so much that it cannot drain fast enough. Hence the flooding visuals we see about Velachery. But even this month, unlike in years past when this drain wasn't there, the water was drained off in a day or two, and areas notorious for flooding within Velachery were back to normal. Another example the baby channel built in the Cooum as part of its cleaning. Due to this, areas like Anna Nagar and Mogappair didn't experience prolonged flooding, and the water drained relatively quickly.
The same problem repeats now, with a twist though. The Pallikaranai marsh is full, and it's own drain to the ocean goes through the Buckingham canal, which also is full. So this time around, the water won't drain as fast simply due to lack of space. The quantum of rain we got this month is unbelievable, and so flooding will happen. Look at the stats: on Tue alone, Chennai received 27.5 cm of rain. Heck, suburbs like Tambaram received 49 cm of rain on Tuesday, which is on top of the earlier spells of rain, which cumulatively totaled 108.8 cm in Nov, the normal average being only 40cm for the entire month! The entire month of Dec gets only 19 cm usually, and that was exceeded in a single day, with more to come. There is only so much we can do against nature's fury.
Heavy rain events happen once in a decade, and some flooding happens. But this time around is a once in a century event. We may not be able to prevent them fully, but at least ensure that the water drains off soon. This past month, for all their faults, the city admin had ensured that - they proactively acted upon standing pools of water and even broke up roads to drain the water. The reason? Preventing outbreak of water borne diseases, especially dengue. It is a testament to their effort that no outbreak happened in the past month. Could they have done better? Of course, but they did try their best.
In general, one cannot build structures optimised for once in a century events.
Having said that, a few things can be done to improve things. Clear all existing waterways and desilt their mouths regularly. This includes the Cooum, Kosathaliyar, Adyar, and the Buckingham canal. Then expedite the canal works from the Pallikaranai marsh direct to the sea, instead of letting it drain to the Buckingham canal as it currently does. That will add a good amount of capacity. Unfortunately, the SG didn't implement this project for some reason, and the CAG rapped them for this last week. Mark out flood plains and stop notifying layouts here. The city has lots of room to expand, use the interiors for planned layouts that are not on flood plains. The well planned radial roads here ensure good traffic movement, so these layouts will be attractive to prospective buyers. Relocate all garbage dumps away from flood plains. The Thoraipakkam one itself is causing most of the problems. Lastly, stop dumping the damn sewage into the rivers - the biggest cuplrits in this are the govt agencies themselves. Idiots.
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