Geographic Coordinate System (GCS)
Most of the spatial data and maps of Nepal are based on two System.
1. Everest 1830 is mostly used in topographic maps and maps produced by governmental agencies like Department of Survey.
2. WGS84 is used in most of the images and maps available over the internet are referenced in this system.
Nepal lies in UTM zone between 44 and 45. The 44 zone covers western half of Nepal and 45 covers the eastern half. This projection is based on WGS84
Due to greater expansion in east-west direction of Nepal, Survey Department of Nepal uses Modified UTM (MUTM) for increasing accuracy in cadastral survey. Based on Everest 1830 the two zones are modified into three zones differentiated by longitude of the coordinate as 81, 84, and 87 covering west, central and eastern Nepal respectively.
Transformation between the two PCS
There is a slight difference between these UTM and MUTM system used in Nepal. We can do geographic transformation from one PCS to the other one by using following parameters:
Similarly, In order to do geographic transformation from WGS 1984 (Source GCS) to Everest 1830 (Target GCS) we use same method with same values with negative signs in front.
Geological Map of Nepal published by Department of Mines and Geology (DMG,1994).
The topography of Kathmandu valley has changed a lot over the years. The rapid urbanization specially after 2070's has made Kathmandu valley a concrete hub with overall change of the land use pattern and drainage pattern. The narrowing of river channels, encroachment of small tributaries has disturbed the water path flow increasing the risk of flooding in the valley.
The topography and land use of Kathmandu valley around 1994 can be seen in the following Topographic map.
What change do you see in your area currently compared to this 1994 map?
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