A research study submitted in partial fulfillment of the requirements for the degree of Master of Science, School of Environment, Resource and Development

Research Studies Project Report (M.Sc.) - Asian Institute of Technology, 1993

In last two decades, many irrigation projects have been constructed in the western Thailand. It resulted in great changes in agricultural production and land use. The study aimed to investigate the land use change in South Suphan Buri province by using remote sensing and GIS techniques and analyze irrigation impact on the land use change. Three Periods of land use maps were produced to detect the land use change. The first map is land use in 1969. The second map is in 1985. The third map is in 1991 which was obtained by classifying Landsat TM image. Maximum likelihood classification method was used in image processing. In the season the image was received, part of sugar cane was harvested in the region and soil was exposed after harvest. It caused mistaken classification between sugar cane field and built-up area, because of their similar spectral reflectance characteristics. GIS supported image processing technique was used to distinguished built-up from sugar cane field. The image classification results are satisfied for sugar cane and rice field, but insufficient for small l and use types s u c h as built - up, water bodies. The three periods of land use maps demonstrate that land use in south Suphan Buri changed greatly from 1969 to 1991. Large amount of orchard was replaced by sugar cane cultivation. Sugar cane expanded from west to east in the area. Major rice field which grows in wet season is reducing in the area while second rice which grows in dry season is increasing. Irrigation played an important role in crop cultivation and land use change in the area. Water supplement by irrigation in dry season promote the cultivation of second rice and sugar cane. Under the new water condition, crops are re-selected to achieve best benefits.