Geographic Information System (GIS) are 
computer-based systems that are used to 
store and manipulate geographic 
information (Aronoff, 1989). These 
systems are powerful sets of tools for 
collection, storing, retrieving at will, 
transforming, and displaying spatial data 
from the world for a particular set of 
purpose (Burrough, 1986). 
5, Digital Image Processing 
ERDAS software was employed to assist 
in the following digital image processing 
steps : 
^ Image rectification and 
restoration 
Image enhancement 
* Image classification 
- Unsupervised classification : 
The type of image classification which the 
use of CLUSTER program in ERDAS 
software. The classified output is useful 
for field checking and for choosing the 
training samples in the supervised 
classification. 
^ Supervised classification : 
The type of image classification to which 
classes identified was based on the a priori 
information i.e. information gathered in 
the field, and is considered as the best 
technique in identifying land use/land 
cover on the image through the digital 
analysis process where the training 
samples was established. 
6. Slope Classification 
The output of the digital elevation model 
(DEM) process in ERDAS TOPO module 
is a slope map which was developed for 
further use. 
3, Land suitability analysis for crops 
The FAO Framework for Land Evaluation 
(1976) served as the basis for the land 
suitability studies undertaken by the team. 
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To facilitate in the processing of data in 
the ARC/INFO GIS software using linear 
combination method, important decisions 
were first determined. These included the 
following : a) parameters considered, b) 
crop requirements, c) score/ranking of the 
condition in the parameters used, and d) 
assigning weights to each parameters for 
final analysis. 
4. RESULTS AND 
CONCLUSION 
4.1 Land —use/Land cover 
maps : The land use/land cover maps of 
the study area were compiled for two 
different periods, namely, for 1983 and 
that of 1993/4, The 1983 land use/land 
cover map was originally compiled by 
Kasetsart University based on aerial 
photographs, taken on November 22, 1983 
at a scale of 1:13,000. The land use 
classes were then normalized to be 
conforned to the land use/land cover 
classification scheme for use with remote 
sensor data adopted by the US Geological 
Survey (Lillesand and Kiefer, 1987). 
(1) The land use/land cover classes of 
1983 were determined to be as follows : 
Classes Hectare % 
Mixed Deciduous 2,195.15 27.97 
Forest 
Dry Dipterocarp 499.71 6.37 
Forest 
Brush and Shrubs 530.20 6.75 
Plantation 6.45 0.08 
Other Agricultural — 4,130.28 52.62 
Areas 
Paddy Fields 431.18 5.50 
Villages 14.78 0.19 
Water Bodies 12.18 0.16 
Kasetsart Research — 28.49 0.36 
Station 
Roads 
Streams 
TOTAL 7,849.04 100.00 
  
(2) Land use/land cover classes for 
1994 are determined to be as follows : 
International Archives of Photogrammetry and Remote Sensing. Vol. XXXI, Part B4. Vienna 1996