[Mystic]

This subject has been dealt in various threads in different perspectives. In this monsoon in 2023, I had seen live on how a couple of hours of rain can bring metros to its knees.

Being a civil engineer myself couple of decades back but jumped to IT, the civil engineer in me makes my blood boil on why we are in such a mess now?

No rains, no crops and no food. We need rains but we need to deal with them. If nature is not in favour of us due to our geographical position on this planet, we as humans must find a solution to adopt to such situations. Just see Netherlands ( means land below sea level) on how they are managing the situation. Even in our own Hyderabad, the storm water drains created hundreds of years back by Nizams work perfectly compared to the newer drains created in last couple of decades.

Why does this concern comes up during monsoons only and every body forgets after the rains are over. I still remember couple of years back when Chennai was devastated by rains. I was lucky that I left from our Chennai home to Bangalore home few hours before complete Porur area was flooded. My in laws in Chennai were marooned and NDRF has to come in boats to help them.

What is the root cause for the present situation. During rains it is frightening to take our automobiles in subways. Is there no permanent solution? After having searched on internet about the Mother Nature and El Nino effect on India during monsoon, I conclude that more than nature, it is more of a bad planning and careless construction of buildings disobeying the basic rules of nature on occupation of water bodies with concrete structures obstructing the free flow of storm water.

In our civil engineering class, our Professor told us that high ways are called highways because they are built at higher elevation and should not be immersed in water during rainfall hindering the smooth transportation.

May be we as Indians are adopting to the situation in our own way as automobile owners by buying SUVs with higher CG so that we can wade through the inevitable waters in monsoons year after year with no solution in the horizon.

[RM Motorsports]

Here is my view and how things changed around me and resulting in flooding in my lane. I have been staying in Matunga, Mumbai since last 40 years. The lane i am staying had all 3 story buildings and each building had a compound with trees and gardens. Never ever my lane was flooded since last 5 years. Since last 10 years all three story buildings around have redeveloped and turned into 8-15 story towers. The compound gardens of old buildings have disappeared and become parking lots.

Since past 5 years i have noticed whenever it rains heavily for a few hours, my lane starts flooding. All the rainwater which was absorbed by the gardens around old buildings now flows back on the road. The foundation of all new buildings is now all concrete which prevents rainwater from absorbing into the ground.

So ya I figure out that one reason of easy flooding is concrete jungle coming around everywhere which is preventing rainwater to get absorbed into the ground like earlier times. I would say flooding is somewhat MAN-MADE.

[shankar.balan]

The main reason is that all storm water drains and other drainage systems are clogged with leaf, debris, litter and the like.
Our inland waterways, canals and the like, are all absolutely full of litter, muck, debris, waste and sewage as well. Plastic bottles, coated paper tea cups and plates from roadside vendors and sundry flotsam and jetsam make for a potent clogging mix.
Its also a fact that our corrupt officials and the powerful builder-politician nexus allow all low lying areas which were once water catchment areas, to become built up completely.
For a perspective on inland waterways and canals just take a look at the Cooum River and Buckingham Canal in Madras. Or any of the small canals criss crossing different parts of Bangalore. And ref low lying areas all built up take a good look around Arumbakkam and Palavanthangal in Madras and S T Bed, KR Puram, Yemalur, Challaghatta, HSR Sector 5-6-7 and the like in Bangalore.
There is nowhere for the excess run off of water, to go. So water backs up and causes flooding during heavy rain.
All the newer areas built after the 1980’s are prone to these troubles. Whereas the areas which came up in earlier times are not.
Most of these woes are self inflicted man made - like continuous lifelong ‘self-goals’.

[PreludeSH]

If we build in valleys, pre-existing canals connecting lakes and even inside lakes what else would happen ? We dont like having buffer zones or natural habitat and tend to fill up every piece of land.

In addition our storm water drains are not maintained properly. On some roads where there is a inlet into the drain, we can even see the inlet being at slightly higher level than the road itself

We have stupid people in charge. They just want work to be done in whatever way, for whatever lesser money in the project (not total cost)

[Rajeevraj]

Originally Posted by Mystic

What is the root cause for the present situation. During rains it is frightening to take our automobiles in subways. Is there no permanent solution?

The reasons are fairly straightforward.

• We just keep on constructing. There is absolutely no control.
• Continuous construction may be inevitable considering our country and population dynamics, the larger problem comes when we don't carefully consider where we build. Whether it is lake beds, buffer zones, valleys, hill side, sea shore.
• Further more, when we construct, we don't think about the drainage and water run off. We mostly go the opposite way, first build out to maximum and then we realize-Oh there is no drain network or it is not sufficient.
• Extreme weather events are on the rise. This is fairly new phenomenon. Where extreme weather events are happening more regularly. Even places which have handled heavy rains are unable to handle these extreme conditions.

Now coming to the roads itself. With all the construction and lack of drainage, the only open areas for water to go are the roads. Once they get there, there is no place to exit also. So roads get flooded. In addition, poor quality work means that road construction standards are not met or maintained. Roads are supposed to slope slightly towards both sides. To allow water to run off quickly. Does not happen in most cases.

Solution? Difficult. Once the monsoons are over, the outage dies down and everyone forgets and the cycle repeats.

[silverado]

1) Old drainage system not upgraded since British Era
2) People throw plastic and the like in drainage causing blockage
3) Nullahs being dumped with waster choking flow of water which then spills sideways

4) Climate change causing frequent cloudburts like events in a smaller area.

If you see this year we were flooded with videos of cars being swept away in some many places across india. Climate change is real and it is showing its dark face across Asia which is the most affected.

[NomadSK]

Ok, here’s my perspective on flooding at Mumbai. This is what I came to know from one of my friend who’s a BMC engineer and was incidentally involved in the study/fact finding committee, after the notorious 2005 Mumbai floods. About Why we are facing this chronic issues every year. I wish it was as easy as described by others.

Simple hydrology logic would be, inflow = outflow will result in no flooding over a fixed catchment area. Drainage system of any area is designed based on Intensity/Duration/Frequency curves of the rainfall. I bet in each of problematic cities these curves haven’t been revised/updated for a long time or having insufficient data to play with. Probably we are playing with the data which is 100’s of year old. I would broadly categorize these problems into four categories;

1) climate change
2) inadequate design
3) rapid urbanization
4) poor maintenance

Efficient drainage system are based on statistical analysis of past rainfall events and the data is generally collected over 50/100 years interval to get to the conclusion.

The current drainage system which was put in place was in British era. It is capable of handling 25mm/Hr of rain and that too at low tide. This intensity is generally exceeded on routine basis in Mumbai. The peak rainfall intensity for a 15min duration exceeds 72mm/Hr which is way above the drainage capacity of the system. When recent IDF curves have been established for Mumbai with a design capacity of drainage system as 25mm/Hr, it has shown a reoccurrence period of less than one year. The whole drain system works with the aid of gravity, with no mechanical means of lifting stations or pump stations to aid the drainage. And to add salt to the injury, certain parts of the city are below Sea level. God save Mumbai if high intensity rains comes during the time of high tide. There is a clear need for upgrading/overhauling the drainage system of Mumbai.

Now what limitations BMC faces to carry out the job;

Lack of information/drawings of the existing utilities. No map of underground cables/pipes/services. So upgrading drainage is nearly impossible, unless the intent is from the top top level.

Slums on drains, encroachment along drains, political unwillingness to change the status quo. Unfortunately these are vote banks.

Lack of civic sense, clogging of drains with debris plastics garbage disposal in drains

Lack of proper maintenance - de-silting of drains or cleaning of drains.

Large numbers of drains are found to be inadequate. Crossing of utility lines which creates hinderance to to normal outflow.

Interconnection of the storm water drainage and sewer water drainage.

Different agencies involved in carrying out the work. Or shifting utilities.

Lack of intent/funding to carry out the drainage up-gradation.

Last but not the least - CORRUPTION, the less I would speak on this the better.

And This isn’t only for Mumbai, we are seeing the environmental changes across the globe due to global warming. Even gulf countries which never faced much rainfall during the last century are seeing considerable amount of wet days during the years and cities are getting severely flooded, becoz it was never anticipated in the first place to have so much of rains in a short span of time and was never designed to cater this rainfall. And a friend in Norway told me, that last few years it hasn’t been snowing the way it used be. So we can see the trend across.

[fhdowntheline]

We are a dirty country, there is no other way to put it. Most of our urban landscape is filled with dirt, debris (construction debris, domestic waste). Add to that lack of town planning, creating lopsided urban clusters resulting in uneven stretching of water/electricity/sewage systems. Natural terrain/topography is ignored for the sake of creating artificial landscapes. We are able to barely survive only because we value heroism over risk mitigation. When flooding occurs you see NDRF and their boats coming out in the blink of an eye. But no one ever thinks of why this may be happening. Expert committee's views on degradation of the Hill/forest regions are conveniently ignored, but disaster relief (from highest level of govt) measures take place in full swing.

[IamNikhil]

Every major metro city in India sees a flood-like situation every monsoon, yet the authorities are always caught sleeping. Doesn't get any more ridiculous than this. Every year you will see different govt departments playing football and passing the buck to one another every time a grave situation develops. ZERO ACCOUNTABILITY!

Our country basically lacks the political will to take errant officers to task, usually because all of them enjoy their respective political backing. This game of quid pro quo is what is the real infestation in a democracy.

[Mystic]

History repeats itself. Same day in December of 2015, I had witnessed the flooding in Manapakkam area of Chennai. I was a bit fortunate that I left Chennai just in time by few hours to Bangalore in my Scorpio wading through water and somehow reached the Bangalore highway. My in laws were not so lucky in Manapakkam home as the water came almost 2.5 feet into their home. NDRF eventually rescued them after our frantic tweeting for help from Bangalore. I had to drive back to Chennai again to open the locker in my Bank which was under water for a couple of hours. Luckily, there were no important documents.


There is no point in looking into breaking news every couple of years on the havoc rains cause in all important cosmopolitan cities. It is either Mumbai, Bangalore, Hyderabad, Chennai etc. What is the root cause. Why we cannot find a solution to it. This thread has some good observations on the root causes. Hope somebody in a responsible concerned Department looks and takes some action.

[ABHI_1512]

80% of the flooding problem in the cities will be get solved if people stopped throwing plastics around which ultimately chokes the drainage system. De-silting of the sewage canals every year also helps big time. Of course, the cities besides the sea or major rivers, for example- Mumbai, Chennai, Calcutta have their own difficulties during heavy rainfall in conjunction with high tide. Blaming the authorities is easy and which is justifiable even but people have to be aware about their own surroundings too.

[deathwalkr]

Filling up of lowlands, clogged waterways and drainages, rampant encroachments.

[SuperGirl_Dad]

Hot from the yesterdays (Dec 4th) chennai rains: just search for Purvankara lake view apartments, Chennai in X(twitter). See how encroachments were made towards the lake and its water escape canal.

Sampler of natures way of reclamation of canals

https://www.youtube.com/watch?v=h6mSKd43gZQ

https://www.youtube.com/watch?v=jm3mgW3zc3E

This is why roads flood up .