Wednesday, 30 June 2010

Mapping a God

Niyamgiri in Western Orissa is currently the site for a number of controversial projects controlled by Vedanta Resources Plc (UK). The Dongria Khond tribe, who inhabit the region, revere the hill as a god and oppose plans to convert it into an open-pit bauxite mine.

This is a 100m-interval labeled contour map of the hill created using SRTM data. I'm thinking about using Landsat data along with spatial data from other sources to see whether visible changes have been generated by the extant projects.

Since this blog is primarily a cartographic display site, readers who are interested (and furious) like me can Google the words [Church England Vedanta bauxite Orissa Niyamgiri dongria khond human rights violations] in any order, or just access Amnesty International's extremely lucid and well-written report on the topic here, for more information.

Friday, 14 May 2010

Arunachal Pradesh: 3km and above

I've been working on some maps of Arunachal Pradesh; working with ArcGIS is NOT fun. However, ArcGIS together with some file-handling tools (Belvedere), basic Python scripting and ERDAS Imagine makes life a little easier. Not much, but a little:)

This particular set of maps was generated to identify high-elevation regions that may benefit from protected status. In this case, all regions above 3000m in altitude, in Arunachal Pradesh, were identified based on SRTM data. This information was then used to mask a composite Landsat image, which is my intended product.

This is a simple SRTM altitude map of the state.

This is a false-colour Landsat composite of bands 7,5 and 4. The Landsat scenes that comprise this image have been taken in the winter months of 1999, 2000 and 2001.

I've segregated the altitudes into two bands to create a mask; the red indicates areas that are above my target elevation of 3000m, while black indicates areas with an elevation below 3000m.

Finally, I've overlaid the altitude mask on my Landsat imagery and adjusted its transparency and colour so that areas above 3000m now show up very clearly. On the basis of pixel ratios, I estimate that these high-altitude regions make up slightly under 25% of Arunachal Pradesh's total land area.

Monday, 10 May 2010

Inverse Distance Weighting

This is a raster map (created by the inverse distance weighting technique) using NASA SRTM data as an elevation source. I've used red panda (Ailurus fulgens) presence/absence data collected by my colleague Tanushree; the scale is a gradient from white (high probability of presence) to black (low probability of presence). The underlying layer is a Landsat false-colour image.

There's no scale on this map because the skewed perspective means that the scale increases towards the horizon, and decreases towards the observer.

Thursday, 6 May 2010

This is a section of the Brahmaputra that flows through Assam. It's a beautiful river.

The Tso Kar Basin

The Tso Kar basin in southern Ladakh is one of the most beautiful places on Earth. It contains freshwater, saltwater, desert, alpine and wetland ecosystems in close juxtaposition at a height of 4600m above mean sea level. These maps show water surface and wetlands in 2000 and 2006. Play spot the difference?

Wednesday, 5 May 2010

Salutations to Ganesha

As the first post, this one has the dubious honour of explaining what this blog is about. Come on then, step up to the mike.


This is a portion of the Pangchen valley, in Western Arunachal Pradesh. It's sourced from bands 4 and 5 of the Landsat 5 Thematic Mapper sensor.