Raj Bhagat P #Mapper4Life Profile picture
Earth Observer, Civil Engineer Tweets: Data-Driven Decision Making, GIS, Remote Sensing, Water, Urban Development, Environment, Maps
N.V.Ramanan Profile picture Chandrasekar Profile picture Guruprakash Ramesh Profile picture 5 subscribed
May 10 6 tweets 3 min read

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. Image Like many streams and canals in urban environment in India, this stream also didnt have any buffer in case of severe floods and jailed with concrete walls and no room for it to breathe. For most of the year, these streams carry sewage water. Image
Dec 25, 2022 18 tweets 5 min read
#Thread on Local Football

WorldCup is over. Though football has lost media attention in India,local football is living& thriving even under difficult situations

As my club is gearing up to organize a tourney, I'm writing this to show d love & troubles, d game faces
@Udhaystalin Image Contrary to perceptions & opinions, Football is quite popular in many places in India like my town (Nagercoil, Tamil Nadu). 300-500 people (mostly young) attend matches even when conducted during the peak of summer and during a working day. Photo taken during pre-match
2/n Image
Oct 3, 2022 5 tweets 2 min read
I am yet to write all my suggestions related to the climate action plan for Chennai which has been open for suggestions

But wanted to say this:
Please DON'T take all these sea level rise maps from the report that depends on climate central. These are INCORRECT.
@chennaicorp What is wrong:
1. Elevation models used for these analyses are incorrect
2. climate changed induced sea level rise wouldn't act like a bath tub where water rises just like that
3. There would be formation of new beaches and erosion and would be different from current topography
Oct 2, 2022 6 tweets 2 min read
1) Throughout the entire south west monsoon season, Bihar and the catchments of the rivers that flow through it have been facing deficit rainfall. But.. Image 2) Throughout the entire season, Kosi river has been flowing above warning level for every day and above danger level almost every day!

Isnt it odd that a river basin that is facing deficit and drought like situation have flood too simultaneously? Image
Aug 27, 2022 7 tweets 3 min read
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 The construction spree on top of the valley system started when the road was expanded along with a toll gate right on top of valley! And other builtup came along the highway too completely causing the valley system to be obstructed.

Jul 2, 2022 10 tweets 4 min read
Short #Thread:

Though heavy rainfall is the trigger, our construction practices of where and how are the biggest causes behind some of the most devastating landslides that are costing both lives and money for us.

1/n Image shows a relatively well vegetated hill slope in #Manipur in 2009
Jun 11, 2022 10 tweets 4 min read
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 Image The river settled some amount of sand in the sea and close to the mouths the sea was shallower and with lots of sand.

2/n Image
May 16, 2022 12 tweets 4 min read

#Visualization shows ownership of Cars, Bicyle, Two wheelers and also the households that dont own any of these

Why is this critical to know?

Prepared by @PratapVardhan @Stats_of_India
h/t @indiainpixels Before going into the thread, let us clarify about the data. The data is an end product of a survey which surveyed around ~6,40,000 households across India

Data represented in this viz are aggregated at state level so rural-urban or other geo nuances might be hidden

May 3, 2022 5 tweets 2 min read
This is a bridge across the #Chambal river near Morena (on the Madhya Pradesh side of the river), massive sand mining operations are happening right below the bridge! So many bridges across India have collapsed because of this activity More images...
Feb 14, 2022 22 tweets 8 min read
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 2)Vaan is one of the many islands found off the coast in Gulf of Mannar. The island along with others are now protected areas.

Vaan island is in the shallow continental shelf part of sea. 3 islands existed to south of it but they were all merged/modified for construction of port
Feb 2, 2022 18 tweets 7 min read
#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 One of the most highlighted map in the survey was that of night lights. It left many wondering whether India actually grew this way. The answer is no and yes. Night lights did increase over the longer period but it is way exaggerated in this map
Jan 21, 2022 4 tweets 2 min read
To protect the borders in #Kanniyakumari District, Travancore kindgom under guidance of Capt. Eustachius De Lannoy built South Travancore lines - a series of fortifications in ~1740s between the ocean & mountains & are now in ruins after being overrun by Company troops in 1809 Except Vattakottai fort, all the other sections of the lines are present as bunds or demolished and now used as roads. Some ruins of the bastions and redoubts are still visible in some places.

Google Earth/Maxar Rendition of Vattakottai fort overlooking the sea.
Jan 13, 2022 9 tweets 4 min read
India - State of #forest report from Forest Survey is out. If you get news articles (how forest covr increased/decreased), read it with caution. Will write detailed comments later, but some small fun for now:

In ch-13 maps, they have given Shaksgam away! Illegal to publish..
1/n They had some city level maps of forests.. And their statistics depended on boundary files and the file for Mumbai is riddled with gaps between subdivisions. There are white patches in between because someone didnt digitize it properly and these errors creep into stats
Jan 7, 2022 12 tweets 7 min read
#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 Palaymkottai was located in KeelKalaKootram, a revenue division in the east side of Porunai river (now called Thamirabarani). The fort itself was positioned to protect the lush farmlands & was at the intersection of the farmlands & pastures which designed its socio-cultural setup
Dec 27, 2021 5 tweets 2 min read
Time for another short story

A small river/stream existed near Angul #Odisha. The land around it was allotted to JSPL for development... The company thought the course of the river was too disturbing and decided to change the course of the river.
However there were other smaller streams that were draining into it (obviously) & since the new course didnt account it, they started stagnating (marked in white circle)
Dec 5, 2021 9 tweets 4 min read
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 In March 2021, the construction started in the river bed where we can see the machines in action. The canal was supposed to be built parallel to the main river but within the bed.

Nov 22, 2021 7 tweets 3 min read
#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 Image Case 1:
Nov 7, 2021 14 tweets 5 min read
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 Image Chennai Metropolitan region (in particular the city corporation) is relatively flat terrain and is very close to sea level. The agricultural activity in the region had prompted construction of thousands of lakes which were shallow and large in area Image
Oct 24, 2021 17 tweets 7 min read
Thread #Haldwani case:
After extreme rainfall in #Uttarakhand, a bridge failed across Gaula river near Haldwani

Rain wasn't sole cause, it just brought d collapse a bit earlier

Himalayan rivers exit mountains & enter plains with great intensity & it is a critical zone It is in this critical section is Haldwani where the Gaula river exits the himalayas and enters plains. Rivers bring huge amount of sediments with them to settle as well as they have high intensity flows during monsoon to erode

Visual shows the location of the bridge that failed
Oct 16, 2021 8 tweets 3 min read
#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 Even after the completion of phase I which was the runway in the northern side and the terminal, the minor valley was not affected significantly as it was all limited to the northern side. One quarry site also remained holding stagnant water.
Aug 18, 2021 19 tweets 10 min read
Viz: #Kaveri river watershed 😍

I would be posting some #maps about the river with finer details in this thread in coming days! Bookmark.. Image FAQ
Data: SRTM
Software: QGIS