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Development of glacial lakes in the Khumbu Himal - Part 3 
Glacier development Do the following for all of the dates: - On the GIS Tool for image: File>Open Theme select 'Imja_1976.shp', and choose Arbitrary and Map based. - Then: Tool>Information. Click on Polygon 1 and note the statistics on the Area (just the number without the decimal points, rounding off the number). Click on Polygon 2 (if available) and note the Area, etc. - Close Information and open the Edit>Theme tool. Click on Tool>New Attribute, name it 'Surface - OK- and fill in your figures for each polygon. Always hit the 'return' after each entry. - By clicking on 'Surface' you will see the statistics just below, which also include the sum. - Save the changes. - Follow the same procedure for the other years.
1. Did the total area of the glacial lakes increase or decrease from 1957 to 2003?
2. How much is the deviation between 1957 and 2003? 3. Between which dates is there the biggest difference? (e.g.: 1957 and 1976 or 1976 and 1986) There is also a radar image of 18 October 2007 which is not geocoded but can be used to calculate the surface. Use: Image>Measure tool. Select: Units>Meters and carefully digitise around the lake.
4. Has the surface increased or decreased since 2003? By how much?
You can also display the enlargement of the glacial lake graphically with ArcExplorer. Open ArcExplorer and add all the digitised themes and the map of 1957 to your view. Arrange the layers (1975-2003) chronologically, starting with the oldest theme on top and the latest on the bottom. The map should be at the very bottom. Here you can easily change the appearance of the themes to visualise the enlargement of the lake in an easy way. By double clicking on the theme, you can access the Theme properties and change the respective colour of each theme. For the style, choose 'solid fill'.
Last update: 16 April 2013
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