Blr Floods - GRADIENT MATTERS. How steep is your SLIDE?

Summary

Highlights

• Bengaluru is equated to a large, naturally occurring water park due to its topography! 🌊
• Ancient Bengaluru had a sophisticated network of tanks to manage rainwater efficiently. 🏺
• Episodes of rain highlight the challenges of modern construction on historic water-filled areas. 🚧
• Topographic maps reveal much about how water flows across Bangalore's varied elevations. 📉
• This old rainwater harvesting system showcases incredible foresight in engineering. 🔧

Key Takeaways

• Bengaluru's landscape is like a giant water park with various gradients influencing water flow! 🌊
• Historical man-made tanks in Bengaluru are over a thousand years old, testament to ancient water management skills. 🏺
• Understanding these ancient systems can provide insights into modern flooding solutions. 🧐
• Using topographic maps can help identify how your location fits into this water network. 🗺️
• The whimsical analogy of Bangalore as a water park helps in visualizing its unique topography. 🎢

Overview

Chapters

• 00:00 - 00:30: Introduction to Bengaluru Natural Water Park This chapter provides an engaging introduction to the concept of Bengaluru as a large natural water park, using humor and local stereotypes. The narrator clarifies that they are not referring to the popular amusement park "Wonderla" but rather to the inherent design and natural water features of Bengaluru City itself. The chapter sets the stage for a deeper exploration of this theme, promising to reveal more in subsequent sections and hinting at the introduction of an intriguing app related to the topic.
• 00:30 - 02:00: Understanding Bengaluru's Flooding The chapter delves into the reasons behind Bengaluru's flooding issues, exploring both historical and current factors contributing to the city's water management challenges. The discussion includes a playful metaphor of Bengaluru as the world's biggest water park, highlighting the severity and absurdity of the situation. While some are eager to find solutions, the narrative acknowledges the complexity of the problem, pointing out that a deep understanding is necessary before definitive solutions can be presented.
• 02:00 - 03:00: History of Bengaluru's Irrigation The author is engaging in a detailed exploration to understand the reasons behind certain issues related to Bengaluru's irrigation system before deciding on the steps to address them. They have spent the past week doing extensive research, including discussions with experts, reading relevant literature, and personally visiting the Bengaluru tank network and Mahadevapura flood plains. This hands-on investigation is aimed at uncovering insights firsthand and sharing those discoveries with the audience, fostering a similar sense of revelation and understanding.
• 03:00 - 05:00: Bengaluru's Topography and Altitude The chapter discusses the intricate network issue affecting Bengaluru's topography and altitude. It emphasizes the need to unravel this problem methodically to understand its complexity. The chapter mentions insights from a previous episode dealing with the differences in rain patterns, metaphorically called 'red versus blue raindrops,' referring to historical climatic interpretations, possibly extending discussions from the 20th century.
• 05:00 - 08:00: Water Slides Analogy of Bengaluru The chapter discusses the transformation of Bengaluru, comparing it from high-tech Highlands to a 21st-century Silicon Valley. It mentions Mahadevpura, referred to as the Valley of the Great God. The narrative also reflects on the historical aspect of the city, specifically episode 2, which highlighted Bengaluru's original design with over 800 kilometers of interconnected man-made tanks, not lakes. These were strategically positioned at different elevations to efficiently capture rainwater for future usage.
• 08:00 - 13:00: Bengaluru's Ancient Tanks Heritage The chapter titled 'Bengaluru's Ancient Tanks Heritage' explores the historical significance of irrigation in Bangalore. It highlights how Bangalore has been a center for advanced irrigation techniques historically, with a focus on the concept of controlled flooding, which is essentially what irrigation is. The chapter emphasizes the importance of the monsoon season, as it is considered one of the most significant events of the year, providing necessary rainfall. The cultural fondness for rain and floods is noted, and the chapter frames irrigation as a specialized skill and an art form, essential for managing water during these times.
• 13:00 - 15:00: Challenges and Future Discussions This chapter discusses the significance of pre-monsoon rain, specifically focusing on the first raindrops that mark the transition from the hot summer to the onset of the monsoon season. It highlights the importance of these initial showers in changing the climatic conditions and possibly setting the stage for broader discussions on weather patterns and their impacts.

Blr Floods - GRADIENT MATTERS. How steep is your SLIDE? Transcription

• 00:00 - 00:30 is Bengaluru really a large water park you know there were a lot of memes and videos that made fun of us but the trouble is they were right we are actually a large natural water park and one of the best designed ones in the world I'm not talking about wonderla I'm talking about the Bengaluru City Water Park I'm dead serious let's take a deep dive and find out more in this episode I will show you a very cool app that you can
• 00:30 - 01:00 play with we'll go a little deeper to understand why certain parts of Bengaluru flooded and at the end we'll have some fun at the world's biggest city water park or rather City in a water park episode 4 a lot of water has flowed under the bridge so far so it probably helps to summarize where we are at this point I know many of you are calling and writing to me and saying but what's the solution and my answer to
• 01:00 - 01:30 you is keep calm and worry on let's do the diagnosis first let's understand why it happens before we get to what to do next you know I have learned so much in the past week through talking to experts reading whatever I can find and going around the Bengaluru tank Network and the mahadevapura flood paints on bike and by foot to see for myself and I try to transmit the same aha that I felt when I found something out to you it is
• 01:30 - 02:00 a complex interconnected Network problem we have here literally from the cloud to the ocean so let's give it the respect it deserves and allow me to unpack it slowly one issue at a time in a logical sequence or at least what appears logical to me so we can understand the why part first after that we can get to what next in the first episode we got some answers from the cloud on red versus blue raindrops whizzed from the 20th century
• 02:00 - 02:30 high-tech Highlands in the Red Zone down to the 21st century Silicon Valley of the Blue zone or mahadevpura the Valley of the great God in episode 2 we saw how the entire area that corresponds to the current city of Bengaluru had over 800 kilometers of interconnected cascading man-made tanks not Lakes at different elevations anu's Chief role was to trap the rainwater store it use it for
• 02:30 - 03:00 irrigation allow it to drain out slowly not too fast interestingly Bangalore was an important center for AI from a long time AI as an actual irrigation most important event of the year was the arrival of the monsoon or the rains malay we like the rain because we like floods in fact irrigation is actually controlled flooding it's a specialized skill almost an art form and we were famous for capturing
• 03:00 - 03:30 every drop the first and the last you know what the first raindrops are called [Music] was all about capturing the pre-monsoon rain the first shower that changes the season from hot summer to the onset of
• 03:30 - 04:00 the rains they seem to have moved from catch the rain to send it down the drain and in episode 3 we saw the impact of black on Blue how we have merely built away in the floodplains below the flooding level and so when there is Heavy Rain which is not in our control we get flooding in some areas which is very much in our control don't get me wrong I'm not saying it's good or bad to construct in the floodplains all I'm saying is that if you do take adequate precautions it's
• 04:00 - 04:30 just common sense I want to show you a really cool website so just go to Google and login Bengaluru topographic map and you get the result or you can go straight to topographic hyphen map.com it's an incredible map and this is what it is you actually get to see Bengaluru as you can see it's all red and basically if you just click your Mouse anywhere you get the altitude above sea level so I'm just clicking randomly and I get 949
• 04:30 - 05:00 meters let me zoom in a little bit this is the high grounds area this is 954 that's just of Mercury Circle that is the highest point in Bengaluru 924 this is the entrance of carbon Park 926 Bangalore Cantonment station 928 malleshwaram 927 bull Temple do you notice that all these important points are all about 920 meters so if we just go back to an earlier time literally they are the skyline of
• 05:00 - 05:30 Bangalore if you stand at Bull Temple it's equally high as cabin park it's equally high as malleswaram and it's a little lower than what is today near Mercury Circle you get a sense of what the layer of the land was within the old city of Bengaluru and which are the high points now you know why kempegowda built his Towers at these high points they were watchtowers and from this height you could literally see the entire land around especially and advance foreign
• 05:30 - 06:00 cardinal directions but I knew they were not in the four directions and now it makes so much sense that if an army is advancing onto Bangalore it walks along the plains Along The Valleys along the gentle slopes it cannot work on the hills and it makes sense that you guard the entrance to the city where the valleys enter and so it's just the topographic map of Bangladesh suddenly put a lot of things to perspective I encourage you to find out how high is your house what's the altitude of your
• 06:00 - 06:30 office go out there log on to topographic hyphen map.com and play with it it is absolute fun now let's look closely at mahadevapura Valley and I've highlighted the four tanks and the four water Parts which by now you should be familiar with I've got the Agra tank the bellandur tank and the virtual tank which are the main big tanks but I've also got a couple of smaller ones Mahadev product tank and shield attack now look closely and see what I've done I've added a few more
• 06:30 - 07:00 locations and their altitude so right on top we have the high grounds at 9 40 meters but as you come here you have silk board at 885 Dum lure at 888 tin Factory at 885 itpl is pretty high 902 and virtual of course is the lowest at 865. so let's do a little thought experiment let's reimagine our city [Music] let's imagine our city is a giant water
• 07:00 - 07:30 park with lots of water slides [Music] where essentially what happens is you have several high points and all the slides eventually end up in one big pool of water at the bottom makes sense and so we were looking at four slides the slide from silk board the slide from dumb lure the slide from tin Factory and the slide from itpl which slide do you think is the most fun slide of all it's four water slides which are all starting at roughly the same height and all ultimately end up in Virtual
• 07:30 - 08:00 tank obviously the most fun slide is the one with the biggest gradient the steepest slope so let's figure that out together [Music] now just imagine this is a cross section of any part of Bangalore and what happens when it rains all the water flows down so several hundred years ago this is how the typography of Bangalore was that when it rained water flowed down slope now what did we do we decided to catch the water and the valleys and so we erected these obstructions or dams through man-made
• 08:00 - 08:30 effort and created tanks so that when it rained this is what happened the tanks filled up and then in the summer we planted Paddy and other crops on the downstream side of the bun and we released the stored water from the tank using sluice gates to irrigate our fields and what happened if it rained too much the tanks overflowed [Music] now let's put some numbers to that let's assume that this highest point is 902 meters and the lowest point is 865.
• 08:30 - 09:00 that gives me an elevation of 37 meters over a distance of about 4 kilometers some of you may already be guessing which area this is wanna guess so this area was called patandur agrahara and this area was called varthur and on the way you had a place called and you had a place called now let's just fast forward to today has become itpl and in all the valleys just behind the Bund they've built
• 09:00 - 09:30 buildings that's a very good way of understanding what's happened so let's just see what happens when it rains and a raindrop lands in itpl and the Raindrop lands right here and flows straight down down here all the way to nalurhali it jumps over the buildings over there and heads straight towards SRI lavanta again jump sword and very happily Lands inwards Road that's one happy raindrop so for those of you interested you can see the exact altitude at the inlet and the exit point of each of these tanks it's just fascinating to understand the gradient so you can see the itpl slide
• 09:30 - 10:00 is just four kilometers long and almost Falls over almost 40 meters in contrast the silk board slide and the dumbro slide are like a long Lazy River Ride almost 12 to 15 kilometers long there's a fall of 10 meters till Belinda tank via the kga that they can literally play for round of golf and come and then the raindrops can slowly drift across the belindo tank which is over two kilometers and then gently fall another 10 meters toward tour and so you get the drift that the water slides from silk
• 10:00 - 10:30 board dumbler and Tin Factory are long lazy rides this is the itpl ride is a steep one and the essential point I'm trying to make here is that gradient matters because it affects the speed at which water comes and when we have a heavy rainfall event this is of critical importance because it decides how quickly the water comes Upstream Downstream we'll discuss more about that in the next part but the main lesson of this whole chart was Bangalore is not just an up and down City and we have a waterfall no we have an up which is
• 10:30 - 11:00 steep we have a down which is gentle slope but we also have many slopes of different gradients and all this put together make for a rather complex situation perfect for a fun water park but very difficult if you're trying to manage storm Waters one thing you must have noticed about the mahadevpura valley my favorite Valley now is that it is larger than the old city of Bengaluru and not only is it larger in size it is also a very gentle
• 11:00 - 11:30 undulating slope and all the water that flows through the valley on either side are the flood Plains or the Overflow zones and if you speak to anyone who's tried to cultivate Paddy this is absolutely ideal the water overflow this stays for a long time and in a sense in the past is to receive rain from the cloud and have Paddy Farms today I'm told we have data Farms sending stuff back to the cloud and so my message to all you folks out there in Delhi and Mumbai and Chennai
• 11:30 - 12:00 and Kolkata which I call Flat cities we are actually an up and down City we have highs we have lows we have a lot of fun slopes we got gradient and gradient matters and my challenge to all my fellow bangaloreans is this please find me a one kilometer stretch of road in Bengaluru that is absolutely flat there is no altitude variance from one end to the other use the app and find out and if you do please post your answer in the comments below I'm waiting
• 12:00 - 12:30 there is one last absolutely crucial information that just stunned me when I first heard it about how old these tanks are I mean if I asked you how old they are you may say 200 years 300 years maybe 500 would you believe there are over a thousand years old I'm serious Agra tank has a written history of over 1 100 years and I know all this because inscription stones have been recovered near the site they've been interpreted and they talk about the dates when these
• 12:30 - 13:00 tanks were actually created who created them the purpose etc etc foreign [Music] and the trouble is most of us don't even know this and all of us in Bengaluru owe a huge debt of gratitude to a team a team of Uday Kumar and other passionate individuals who are part of the Mythic Society and it's a project it's more a labor of love called
• 13:00 - 13:30 inscription stones of Bengaluru where they are meticulously identifying documenting interpreting and preserving hundreds of such stones that are found all across the city that we call Bengaluru today which actually captures the story of our city and one of the most important stories that I've been able to get out was that Bengaluru was part of an ancient but extremely sophisticated perhaps one of the oldest rain water harvesting systems anywhere in the world and unfortunately due to our
• 13:30 - 14:00 indifference and callousness we haven't tried to understand it and we have almost destroyed most of it over the past few decades this was a feat of human engineering over the centuries and this is something that I'm going to talk about on my next episode when I talk with sir m vishwesharaya India's finest engineer Statesman of the 20th century and the sun of the soil he was born a few miles Downstream from virtur and I really look forward to meeting him because I'm going to ask him what would
• 14:00 - 14:30 he have done to help protect Bangalore from floods and maybe there's something we can learn from him so until the next episode oh wait wait wait you know it's been a crazy week for me since I started these videos a lot of people are contacting me they think I'm some kind of expert I am not I'm just a regular Bangalore and who's curious who's trying to find out about why my city floods and whenever I find something out I tell you and so now when anyone asks me how are you my answer is high and dry
• 14:30 - 15:00 how about you [Music] foreign