GIS Blog

GIS in Action – Crowd Sourced Mapping of Earthquake Impacts in Nepal

This post looks at how GIS is being used in a crowd sourcing way to respond to humanitarian needs around the world. 

Recent event in Nepal have been eerily familiar – many of will know what it’s like living in the shadow of aftershocks and the long road ahead.  There are lots of ways we can help, like contributing money or donating supplies.  Those with a geospatial bent now have another way to contribute to work on the ground, and not just in Nepal, but in many other places and on a variety of different projects, but specifically with helping to build up accurate maps of places affected by some sort of problem.  This is crowd sourcing at its geospatial  finest, methinks.

Let’s start by looking at Humanitarian Open Street Map and their OSM Tasking Manger in particular.  This website is allied with Open Street Map (OSM), a crowd sourced mapping tool along the lines of Google Maps but more like Wikipedia in that anyone can contribute.  I’ll have more to say about OSM in another post, but for now, let’s have a look at the Tasking Manager:



There are a number of projects listed here, all related to Nepal.  Each can be clicked on, leading you to a gateway of a requested task.  Organisations (the Nepalese government and NGOs in this case) put requests in for mapping tasks needed and anyone, anywhere, with an internet connection can help.  Here’s the page for the first one shown above


On the map we’re taken to the project area which has been broken up into quadrants, and a common mapping task for each.  Status is indicated by the colour of the square.  Clicking on the “Instructions” button takes you to this page:


This pages gives us some background on what’s needed.  At top left, the “Entities to Map” tells us that they’re needing “roads, buildings, settlements, waterways” to be mapped.  Further down, under “TAGGING GUIDE” we’re told that they’d like us to “Trace all roads. Often in the mountains, only paths exist. Trace these paths and assure to connect them to the road network”.  Later on we’ll see that we can do this on top of a recent satellite image.  So for this task we’re helping to map the roading infrastructure as part of the response.  Whatever data we add are then available to the Nepalese government for their own mapping and analysis.  Neat, eh?  Let’s go to the “Contribute” page and see how it works.


We’re just about ready to start mapping.  We could click the “Take a task at random” button to be taken to one of the unattended to squares.  Alternatively, we can pick one based on the legend at lower left:


From this we can see that 4 areas are currently being worked on.  The grey ones haven’t been worked on yet.  Any labelled as Done have been mapped by someone but not checked for accuracy by someone higher up the food chain.  Those that have been Validated have been mapped and checked and are now part of the global Open Street Map database.  Let’s have a look at a random task:

RandomTaskWe’ve zoomed in to one of the unvalidated squares and are just about start mapping.  To take part I’ll first need to log in to Open Street Map and then I’ll click “Start Mapping”:


Above, the drop-down menu for “Edit with” is shown.  We’re going to be looking at a satellite image and using some built in tools to create lines on any roads that we see.  I’ll click the iD editor and let’s see how it looks.


A new tab has opened and we can now see a satellite image as a backdrop plus some editing tools.  We can see familiar GISy things like Points, Lines and Areas.  We can also see that someone’s already been doing some work on this area.  If you look at one of the earlier images you’ll see there’s some information on who’s done that work and when.  If we want to contribute, we would scan around this image and either adding new data on roads, tracks and paths if they haven’t been digitised in yet, or making corrections where appropriate.  When we’re finished, we can move back to the original tab and click Unlock or Save.  This saves what changes I’ve made and will alert someone at HOT that this areas needs to be reviewed.  Again, once this area has been validated, it’s labelled as Done and we’ve helped in some small way with the response to their earthquakes.  All from the comfort of our own desktop.  Back at the main HOTOSM page you can have a look through all the different projects and levels of completion.  They range quite widely, from disasters to wildlife mapping, to social impacts.  A good chance to put your geospatial skills to good work.

Another example of this is


This based on the same idea of citizen mappers.  As with HOTOSM, you’re able to map features based on satellite imagery.  As you can see above, they’re focused on damaged buildings, major destruction, damaged roads/bridges and the presence of tents/shelters.  Clicking on “Start searching” takes you here:


One difference with Tomnod is that you make use of pre- and post-event images so you can assess what’s been damaged or where tents or shelters have been established.  There is a similar type of online editor that allows you to digitise and tag what you see on the map.

There are more sites of this kind out there, built on the idea that we can visually interpret what’s on satellite imagery as a contribution to the earthquake response.  We’ve probably all heard the stories of remote areas that have yet to be reached by search and rescue.  Here we can directly help with that, with the satellite images taking us easily to those difficult to reach places – we can be the eyes in the sky to help let the people on the ground know what’s happening.





• 18/05/2015

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