Methods

For this project, factors such as Land use, major rivers and major roads were used with different weightage. Land use was given 55% usage, major rivers 35% and major road 10%. These weightages were purely based on assumption. Land use was given more weightage assuming that it was more important to consider land depending on its current use (water body, forest area, built up areas). Rivers were give 35% because it was more important to base the site relative to river since roads was the least important because constructing access road was easier than controlling river or land use.

i. Data sources:

Airport data was obtained from the ESRI website. Nepal’s airports were refined from the list of all airports around the world. The data for major rivers and majors roads were obtained from International Centre for Integrated Mountain Development (ICIMOD). They work to study and share information related to Hindu Kush Himalayas regions. Countries like Nepal, India, Afghanistan, Bhutan, etc. fall in this region.

ii. Projection used:

WGS_1984_UTM_Zone_45N projection was used with false easting 500000 and false northing 0, central meridian was 87 and the linear unit being in meters. This projection was used because Nepal lie in UTM Zone 44N and 45N. And the data are usually collected using the 45N projection.

iii. Software environment:

The software I used was ArcMap. The software uses a lot of memory which made the computer lag a lot at times. If I had more time, I would have tried transferring my map to ArcScene and get a 3D view of the site locations. I wanted to show the selected sites in Google map but due to time constraint I was not able to work on it. The data I used were all raster data. In the end, I had to convert the final map from raster to polygon to calculate areas.

iv. Analysis:

The river data was buffered for 1km distance and the road data was buffered for 100m distance. This was done basing on the assumption that it is most suitable when it is closest to existing road. And assumption that an airport should be at least some distance away from rivers. The Euclidean map was obtained from the buffered map, using the Euclidean distance tool. The map was then reclassified that represents closer to the road the better and farther from the river the better. After getting the Euclidean map, land use map was then reclassified according to suitability class. Shrubland/Grassland/Barren Area being the most suitable and Water body/Snow/Glacier/Built-up area the least suitable or unsuitable. All these tools were applied using the model builder which was a very helpful and easy to understand because of its flowchart format.

These three maps were then weighted using the raster calculator, River*.35+Road*.1+Landuse*.55, to get the weighted map. After the weighted map was obtained, majority tool was used to get a map that took the majority area from the surrounding up to 4 cells. The map was again reclassified in the range of 1 to 5. Where 5s are the most suitable and 1s is the least suitable area for airport site. The map was then changed to polygon using the conversion tool in order to calculate the areas of the site. The areas were calculated using the calculate geometry tool and the unit of the area is hectare. Only areas from southern plain was shown assuming it is most feasible because of the very less varying grade land structure. From the areas in the southern plain, different ranges of areas were selected which were large enough for at least a two runway airport.

Figure 2: Weighted Map