Designing spatial information system to facilitate agricultural land evaluation in Chiang Mai province

Thesis Abstract of AGS Students

Designing spatial information system to facilitate agricultural land evaluation in Chiang Mai province

Sirichai Chupraphawan (1993)

A spatial database was designed to manage and analyze spatial data sets with related attributes in raster and vector formats to facilitate land evaluation and land resource planning. The Prao district of Chiang Mai province was selected as the study area. The spatial databases consist of soil, land use, road, surface hydrology, administrative boundary and elevation. The spatial data were digitized by using the PC ARC/INFO package in a vector format and stored as map sheets in separate files. Data transformation was also done from the vector format to the raster format in IDRISI environment for further analyses.

A system shell was developed for linking spatial database and non-spatial database to display spatial information as thematic maps, for land evaluation process and for displaying the output maps. The system shell was also designed to interact with a user both in English and Thai languages in form of a pull-down menu under FoxPro 2.0 software environment on a microcomputer platform.

Four methods of suitability rating were used for land evaluation, the Fuzzy land evaluation, the Law of Minimum method, the Multiplication method, and the Modified Multiplication method. All of them were based on United Nations Food and Agriculture Organization (FAO) framework for land evaluation. Two variations of land use requirement (LUR) were tested, one was described by FAO and the other was defined by Department of Land Development (DLD).

KHAT statistics were used to compare the results of suitability ratings by different methods. It was found that there were discrepancies between the suitability maps evaluated by different LUR descriptions. The LUR is considered to be important information to deserve more attention for future development of land evaluation process in Thailand. The Modified Multiplication method and the Fuzzy land evaluation methods functioned reasonably well in rating land for its absolute and relative suitability respectively.

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