#Thread
on Ponniyin Selvan
#Maps
Last year, I had the opportunity to work as map consultant in director Maniratnam's magnum opus,
#PonniyinSelvan
movie. Though seen only in bg, there was a lot of professional effort put into maps which must be the 1st in Indian film industry 1/n
Here's a compilation of my
#maps
which can help you in understanding the
#Bengaluru
#Water
situation a bit better.
Bengaluru is unofficially a hill station which is located nearly a kilometre above sea level.
Here is the story of how
@googlemaps
helped me recover items stolen in a moving train from my father.
My father was travelling from Nagercoil to Trichy in sleper class in Nagercoil - Kacheguda express. He had boarded at 1:43 AM from NCJ. The train was relatively empty & another
#Viz
: Ocean floor around India - If you're wondering how it would look like without the sea water.
Exaggerated relief. The Bengal and the Indus fans are the largest of their kind in the world. Their approx area marked here along with their canyons :)
#Map
shows literacy rate in South India (2011).
Each village/town in each Taluk is represented as one dot. Blue =Good, Red=Bad
So many stories in one map!
Short thread:
#Chennai
, lakes, and floods
I have written some threads about the flooding in Chennai, this one would focus specifically on the lake aspect.
#Map
below shows the flood forecasted areas in Chennai for an extreme amount of rainfall. If we carefully look into this
#Thread
:
Since many had asked this, Writing a short thread on the formation between India and Sri Lanka
Usually many get deceived by "static" satellite images and believe that the Tombolo section as permanent relics of a man made bridge.
Fun Geography fact:
96.7% of Indians live at an elevation lesser than or equal to that of
#Bengaluru
87.5% of Indians live at an elevation lesser than or equal that of
#Hyderabad
Map shows the areas of India which are at lower elevations than these cities
#HillStations
Short
#Thread
: Does the
#Cauvery
river need another dam?
Kaveri river is one of the most exploited watersheds in the world and yet there are many calls from both Tamil Nadu and Karnataka public to build one more mega dam
1/n
#Thread
: Here are my views on use of satellite images & maps in the Economic survey 2022.
Overall I have a mixed feeling. I am so glad and delighted that a section has been devoted in this manner but I am not happy how certain maps have been presented as they tend to mislead
Thread - India's flood plain issue:
There r so many flood incidents this year. One big problem s that we haven't mapped flood plains yet. Many crucial infra (road, railway) are built in flood plains with less care
Kabini Flood simulation shown here
FYI
@PrinSciAdvGoI
1/n
A Kutty (Short) Story with Satellite Images about a hamlet near Tirunelveli,
#TamilNadu
In 2003, the hamlet can be seen (marked in orange). It is next to Tirunelveli - Madurai railway line. There's a crossing (marked in black) through which people went to the nearby main road
#Viz
: Map shows the water divide in India
Surface water flow from rainfall to the left of green line flows into western seas (Arabian etc.) n the right of the green line drains into eastern waterbodies (Bay of Bengal etc.).
Endorheic Basins (that dont drain into sea) not shown
#Satellite
image from today morning at 9:15 AM showing the fog cover over Northern India.
Notice a hole in the fog cover over Delhi's urban agglomeration. The fog is lacking over there primarily because of urban heat island effect
#Thread
Many parts of
#Chennai
have been inundated after heavy rains (22 cm) last night. The city like all other in India faces a wide range of issues and it is UNLIKELY to solve any of the urban flooding related problems that it faces within the next 10 years.
Here's why
1/n
People used to scratch the paint and covers in bus seats, vandalize heritage buildings, rocks etc to record such messages. Now they are using Google Maps.
அடேய்களா...
#Viz
After seeing 2D map of rivers, many suggested to connect Himalayan rivers & SI rivers
Though Ganga originates at higher elevation,majority of it's course is at lower elev than SI rivers (let alone watersheds).Pumping wud be very costly
Forget Interlinking!
#WorldRiversDay
#Thread
A collection of geographical myths & unknown facts about
#Kanyakumari
1. Kanniyakumari is NOT the southern most point of mainland India, the southern most point is near star of the sea rock in nearby
#Kovalam
. In the last 20 years,it has been popularized as sunset point
Thread:
I'll summarise the
#Chennai
cyclone event and the flooding issue once again as I feel that there is a lot of misinformation floating around which could guide people and government in wrong way w.r.t future actions
#ChennaiFloods2023
1/n
#Short
Story/Thread :
In 2003, A stream/river (seasonal) was flowing in
#Dehradun
near Sahastradhara Road..
Satellite Image snapshot from Google Earth
1/4
#3D
Map for today:
Tamil Nadu, Sri Lanka, Kerala, and an Ocean without water.
Approx depths (w.r.t current mean sea level) marked for reference. Exaggerated Relief.
Thread:
I had earlier posted that I am not confident about Covid Nos & few asked explanation
Attaching satellite images where SWIR bands have picked up fire signals in crematoriums(orange colour). In most cases, this is 1st time detected or ten times intensity detected in past
Useless geographical fact for the day:
Did you know that
#Chennai
is slightly more "north" than
#Bengaluru
?
#Map
shows the cities & their respective urban area at same scale and latitudes
It is critical to understand the past courses of
#Porunai
river (Thamirabarani) to study history better
#Korkai
once a thriving port city was closer to river & sea but is now kms away
Sedimentation by river & sea have changed the landscape
#Map
shows my version of old course
#DYK
: Nearly half of India's population lives in the Ganga-Brahmaputra hydroshed!
Map shows population share of each of the hydrosheds (derived from elevation data)
#Map
shows the submarine cable system which are in the ocean floor that is vital for Internet!
Every time we transfer data from an US/international server, that data travels in these cables 1000s of meters below sea surface..
In India cables land primarily in Mumbai & Chennai
#30DayMapChallenge
Map 2: Lines (Only one line though 😋)
#Viz
shows the elevation profile of Nilgiri Mountain Railway in Tamil Nadu which is an UNESCO world heritage site
#Map
showing Hebbal valley in
#Bengaluru
. Have said many times, more than lakes, the valleys are important to understand and reduce flood damages in cities
But we are building right in the middle of valleys.
Read Tweets below to see how the areas marked in red were affected
#Thread
-
#Bengaluru
Airport:
What exactly happened in Bengaluru airport that led to the flooding/stagnation a few days before?
My version:
Before the airport, area (marked in white) was in a ridge between 2 valleys, had cropland, quarries, a minor valey, open scrubland
1/n
Digitizing the village locations in Little Andaman..
Started digitizing village/town locations in India 4 years ago & it is almost over now 😍 so delighted!
This is my current work desk (no one asked but....)
#Thread
: A Problem in the making. Two major problems faced by
#Bengaluru
are flooding and traiffic. But just like any other Indian city, unbridled urbanization is aggravating these crises and is making sure that these problems would stay for longer
1/n
#30DayMapChallenge
Map 1: Points
Thermal anomalies observed across Northern India in the last one week. These are primarily stubble-burning crop fire incidents in
#Punjab
.
#Thread
Story with maps about Vaan Theevu, a small island off the coast of Thoothukudi, Tamil Nadu.
Animation shows how much the Island has changed over last 3 decades. It has been shrinking for a while.
Here's my take on the subject. Please do read this long thread!
1/n
#Satellite
observed night lights for
#Karnataka
(temporal composite)
Karnataka is a classic example of "primate city" where in 1 city (
#Bengaluru
) has over grown when compared with other cities
IMO: India's Megacity led growth trend is coming to an end (since 2015)
#Map
shows the number of Government of Hospital
#Beds
available per 10,000 people (2019).
We have to invest more in our health infrastructure in such a way it is geographically accessible, financially and socially inclusive manner
@zomato
Don't end it with Tamil. Build the app versions for Kannada, Telugu, Malayalam, Bengali etc. You dont have to wait for an incident to do these :)
Now that
#EVERGIVEN
is unstuck, what would it look like if it drifted to India & got stuck?
Mumbai - Marine drive: Between stadiums
It can be alternative to Kolkata-Howrah Bridge
Kanniyakumari: it can serve as a bridge between rock& mainland
Kochi: it can block the backwater!
#Visualization
of Western Ghats from the west. This is the
#topography
behind some of the wettest places in India
These regions (marked) recieve heavy
#rainfall
when
#monsoon
winds hit the western ghat escarpment in a process known as orographic lift
Short Story: 🧵
Near wonderla exit in
#Bengaluru
- Mysuru road, there existed a valley system (flow directions indicated below). Few irrigation tanks were also there in the valley (marked in blue).
1/n
Let me clarify once again on this usual forwarded message of NASA
#satellite
picture of India during
#Diwali
:
The actual image composite is NOT fake, Interpretation is wrong - I.e. it is not Deepavali night and has nothing to do with it.
So what is it?
It is a temporal
#Map
of
#Karnataka
shows the leading agricultural commodity produced in that village.
Villages will have more than one commodity. Map shows the first one as reported in Census 2011.
Short story/Thread:
There was a Madras high court order on lake encroachment & judge said "whether it is 112 crores or 1K crores, we will destroy it. Get bulldozers ready"
But my lord, Madurai Bench of Madras High court was constructed in lake
Old Satellite image attached
1/n
Short thread of satellite images
Story of a navigational canal that was built with ~12 crore rupees tax payer money in
#Ganga
riverbed in
#Varanasi
Uttar Pradesh.
h/t
@Indian_Rivers
Before the construction of the canal, this was the river Ganga
1/n
No Playgrounds, No setbacks for buildings, No trees 😡
Many of our
#schools
are mere concrete cubes that manufacture candidates for entrance examinations & are not a place of learning where children gain skills to become human beings
Some schools with satellite images shown:
Popular Request:
Linearly exaggerated relief of Mainland - India 😇
The reason why I didnt do this in the past is because when exaggerated linearly , Himalayas look like a wall and the finer details in Topography get lost
#Thread
on Koshi and Bihar Floods:
Though there are articles on Koshi River n flooding in Bihar, I prepared this thread to visually explain it!
Image: Topography of
#Bihar
Despite being far from sea most of Bihar people live at an elevation lesser than 100m similar to Kerala
On 15th January, an underwater volcano erupted in
#Tonga
. It sent shockwaves across the globe.
#Shockwave
reached India around 7:30 PM & moved across country for next few hours. The change in pressure was recorded by IMD's weather stations
Animation shows the change in pressure
#Thread
Another city, another neighbourhood, another stream but same story
This is about a nala that flows through the dense urban concrete jungle of
#Hyderabad
city. It flows through Padma colony of nallakunta neighbourhood and eventually joined Musi river.
Government institutions like IMD charge lakhs/Crores of rupees for accessing historical weather data created with taxpayer money. But they provide the same to select institutions (ex: IISc) free of charge. Researchers outside would never get to study or publish in such domains
#Viz
- Kanyakumari District
DYK: Even though closer to sea, many mountain peaks in Kanyakumari district are taller than peaks found in 15 Indian states (Punjab, Haryana, Bihar,UP, Jharkhand, Chattisgarh, MP, Maha, Telangana, AP, Odisha, Rajasthan, Gujarat, Tripura, Goa)
#Home
Due to popular request:
#Satellite
observed Night lights for
#TamilNadu
(Temporal Composite)
Tamil Nadu also has a primate city,
#Chennai
but unlike Bengaluru which is 8 times larger than Mysuru, Chennai is larger by 4 times than the next largest city in the state (
#Coimbatore
)
#Satellite
observed night lights for
#Karnataka
(temporal composite)
Karnataka is a classic example of "primate city" where in 1 city (
#Bengaluru
) has over grown when compared with other cities
IMO: India's Megacity led growth trend is coming to an end (since 2015)
Meandering of River
#Ganga
- Animation shows the dynamic nature of the river and how it's course changed in the last 3 decades in
#Bihar
.
These are the ones which we're trying to control using Embankments. Shown with a Google Maps backdrop for reference.
#Rampur
is the most commonly found name in India as per the Census' village list.
#Map
shows the villages named Rampur. The name is highly concentrated around UP, Bihar, WB
This is based on what was analysed by
@zeusisdead
Underlying data is from
@MapMakinMeyers
Short
#Story
of a river, a sea, a fishing village, and a groyne
Satellite image from 2005 shows the delta of Porunai river (Thamirabarani) in Thoothukudi district of Tamil Nadu.
1/n
What would PM2.5 observations depicted in 3D look like?
Satellite observations of PM2.5 across
#India
from 2018 shown in visualization. Gangetic plains become a big mountain range peaking around Southern
#Delhi
Map of
#Karnataka
showing villages which have
#Coconut
as one of the top agricultural produce.
Coconut which is native to coastal regions is being grown at inland even at heights of 800m (& greater) above sea level!
#Map
Nearly a billion people in India would have faced high temperatures (above 38 degree celsius) today and around 80% of it might have faced 40 degree celsius today.
#heatwave
#Map
shows
#India
divided into 4 sections of equal population sorted based on height above mean sea level
Each colour denotes a quarter of India's population
25% of people live at an elevation less than 60m
Another 25% live between 60m & 165m
The role of Western Ghats:
#Map
shows 2020 rainfall overlaid on a terrain map. Left side is Kanyakumari District which received more rainfall and on the right side is Tirunelveli Dist which is rainshadow!
#Visualization
shows the topography of the region around
#Bengaluru
& the water divide is shown in red colour
Surface water to the left side of the ridge line flows into Cauvery River & water to the right side flows into Ponnaiyar/Dakshina Pinakini/South Pennar
Thread of some beautiful
#satellite
images captured last week
1. Waves crashing in the mouths of
#Godavari
river, Andhra Pradesh. The sand deposited causes the waves to break farther from the coastline
#Map
showing the ratio of workers in work other than
#Agriculture
to the total number of workers as per census 2011
Each dot depicts a village/town in each subdistrict (slightly normalized based on total workers)
Red : More agricultural workers
Blue : Less agricultural workers
1. Short term disaster responses & on ground actions - Excellent
2. Forecasting and associated preparedness - Excellent
3. Hotspot Management - Good
4. Storm water drain plan - In works
5. Streetscape plans - Requires work
6. Rehabilitation plan for low lying areas - not in place
One more fun geographical fact:
25% of Indians live at an elevation lower than / equal to that of the top of the Thiruvalluvar statue in
#Kanniyakumari
#Map
shows areas corresponding to them. States like Bihar, Assam which don't have a coast are at lower elevation
Please note
#Thread
of maps on Palayamkottai, now part of
#Tirunelveli
As a city,Palayamkottai has a recorded history for more than a thousand years. It reached its zenith during the British era & was called as "Oxford of South India"
My first thread in 2022 is a tribute to
#ThoPa
Cheering you up!
#Viz
shows the famed
#Kolli
hills road in Namakkal district
Inorder to achieve a vertical displacement of nearly a kilometer & reach a place 3.5 kms far (aerially from the base), the road takes ~70 hairpin bends thus covering a distance of more than 20 Kms....