Urban Change Study Using RS And GIS

To investigate the changes that have occurred in the city during the market economy a false colour image was created using SPOT XS bands of 1997. For the improvement of the interpretation and the detection of the boundaries between the selected classes of objects, band 3 of the colour image was edge-enhanced using a 3x3 convolution filter (central pixel 10 and other values -1). The created colour image is shown in figure5.



Then, on the enhanced image the selected classes were screen digitized. Furthermore, the digitized vector map was rasterised with a pixel size of 10m and the total number of pixels falling into each of the classes has been calculated. The result indicated that during a 7 year period ger area had increased by 50% while building parcels had increased by 48%. At the same time, population of the city had become 649.800. The reasons for these changes are:

1. due to the market economy people moved to the area with a good infrastructure;
2. during the market economy income of people has increased and the built houses are mostly cottages or houses with few floors, not like building blocks;
3. due to the new land law which gives a distinct right to land owners [6], the interest of people to own land parcels has increased.

A map indicating the changes occurred in Ulaanbaatar area during the market economy is shown in figure 6.



Conclusions
The overall idea of the study was to compare the general changes occurred in central part of Ulaanbaatar area during a centralized economy with the changes occurred during a market economy and describe the socio-economic reasons for these changes. For this purpose, multi-temporal RS and GIS data sets were used. As seen from the analysis, during the centralized economy significant changes occurred in the ger area of the city, while during the market economy significant changes occurred in both areas. Surely, this is just a rough estimation of the changes of the capital city. For the proper estimation, large scale maps and very high resolution satellite data (eg, IKONOS) or aerial photographs covering all areas should be used.

Acknowledgement
The authors are very grateful to Ms.O.Tsolmongerel and Ms.Sh.Tumentsetseg for digitizing a city map of Ulaanbaatar area, and Dr.P.Galsan for his valuable advice in the study.

References

1. Amarsaikhan, D., Tsolmongerel, O., 1997. Some Results Of Using Spatial Enhancement Techniques. Journal of Informatics, Ulaanbaatar, Mongolia, pp61-68.
2. Amarsaikhan, D., Ganzorig, M., Tsolmongerel, O., 1997. Comparison of Spectral Enhancement Techniques. Journal of Informatics, Ulaanbaatar, Mongolia, pp35-39.
3. Dirk Bolt, 1996. An Urban Community Strategy For Implementing Decentralization And Devolution Policies. ITC Journal 1996-1, pp18-28.
4. Hans de Brouwer, Carlos R Valenzuela, Luz M Valencia, Koert Sijmons, 1990. Rapid Assessment of Urban Growth using RS-GIS. ITC Journal 1990-3, pp233-235.
5. Jan Turkstra, 1996. Urban Growth And Land Use Options For Lower-Income Groups: A Case Study Of Villavicencio, Colombia. ITC Journal 1996-1, pp57-64.
6. Land Law of Mongolia, 1994. New Land Law of Mongolia. Ulaanbaatar, Mongolia.
7. Statistics Report, 1999. Statistics Report Intended to the 360th Anniversary of Ulaanbaatar. Ulaanbaatar, Mongolia.
8. Tsegmid, Sh., 1969. Physical Geography of Mongolia. Ulaanbaatar, Mongolia.