eucalyptus and Casuarina are commonly 
planted in these tree plantations. Big- 
sized trees of Pterocarpus indicus are 
usually growing far apart in the farmlands 
of most villages. 
3. METHODOLOGY 
The main project of this study involved 
interdisciplinary team approach in order to 
determine the existing situation in the 
study area to identify the development 
issues, biophysical and socio-economic 
conditions, and the relationship between 
people and their environment. 
The  interdisciplinary team work 
consisting of three functional groups were 
employed, consisting of biophysical and 
institution, socio-economic, and 
environmental remote sensing and 
geoinformation groups. lt is the work of 
the environmental remote sensing and 
geoinformation group that is being 
presented in this paper. 
STEPS OF WORK PERFORMED IN 
THE STUDY 
I. Data Collection 
This activity involved the collection of all 
the major and ancillary data required to 
meet the above stated objectives. Soil 
map, hydrological map, reservoir map, 
aerial photographs (1983) and land use 
map dervied from the landsat TM image 
taken in July 1993 and January 1994 were 
considered as the major sources of data. 
Crops requirements and the limitations of 
crops selected were also gathered. 
2. Map Preparation 
Using the available topographic map of 
Lop Buri Province sheet no. 5139 I, dated 
1969, base map of the study area were 
prepared prior to digitization. Different 
coverages of the study area were prepared 
separately but each had the same boundary 
of the area, following the boundary 
611 
provided by Kasetsart University. These 
coverages included : 
(1) the boundary map of the 
study area derived from 
the topographic map 
provided by Kasetsart 
University ; 
(2) the transportation map, 
i.¢. road network in 
1983 and in 1993 ; 
(3) the drainage patterns 
(main stream and its 
tributaries, canals or 
klongs) ; 
(4) reservoir map ; 
(5) land use maps in 1983 
and 1994 : 
(6) slope range map ; 
(7) geological map ; and 
(8) village location map 
The preparation involved some from of 
ground reference data. Eight (8) Ground 
Control Points (GCPs) were marked on all 
maps. For image processing purposes 
(with use of CCTs), GCPs are essential for 
computing a transformation matrix for use 
in rectifying an image (ERDAS Field 
Guide 1991). The GCP values were 
converted into Universal Transverse 
Mercator (UTM) values for the purpose of 
digitization. 
3. The Global Positioning System 
(GPS) 
Global Positioning System (GPS) is a 
satellite based navigation and positioning 
system that can accurately georeference 
and type of spatial information in almost 
any place of the earth. GPS is able to 
provide map coordinates of either 
latitude/longitude or the Universal 
Transvers Mercator (UTM), the elevation 
of the observation point, the time when 
the record was taken, the prescribed zone 
value of the point location and others. 
using 
4. Basemap Preparation 
ARC/INFO-GIS 
International Archives of Photogrammetry and Remote Sensing. Vol. XXXI, Part B4. Vienna 1996