My hometown Chennai is facing one of the wettest monsoons of the century, recording close to 120cm of rainfall this month. Daily life for over 6.7 million people was disrupted and the media called attention to the situation. Unsurprisingly, there is virtually no data available to identify which parts of the city were most affected, and vulnerable to such climate phenomena.

To get a clearer picture of how the city has been affected, Sanjay, Aruna and I built a map based tool to report flooded streets using OpenStreetMap data. You can zoom into a locality, visualize which streets are reported as flooded (pink), and click on a street if you know it is flooded.


In the last 24 hours, over 2,500 streets have been reported as flooded by the citizens of Chennai using the tool. Although not individually verified, these contributions show patterns in the city and residential zones built around large waterbodies and wetlands that are vulnerable during the monsoon.

The map consists of a base layer of low lying areas created using elevation models from ISRO and NASA, and inundated areas from UNITAR. The map interactivity was built using Mapbox GL and is hosted on GitHub.

Do catch me or Aruna on Twitter if you would like to get in touch and expand this tool for your city.