4. Data sources
The change detection in the PWLS was derived from thefollowing sources.
1) Aerial photo (1:50,000) acquired in 1976
2) Multi-temporal Landsat data acquired on March 17,
1998 and February 25,2005which corresponded to
the dry season.
3) Topographic maps of the Royal Thai Survey
Department at the scale 1:50,000 which were used
for geo-referencing and supplement informa