2. THE STUDY AREA AND ITS 
VICINITY 
2.1 General Description : 
The study area is a part of Khok Charoen 
District, Lop Buri Province in the upper 
central region of Thailand. Specifically, it 
is located in the Yang Rak Sub-district 
with latitude 15?15' to 15?27' and 100?52' 
to 101^00' (figure 1). 
2.2 Climate of the Study 
Area : 
Based on the 11 year climatic record from 
the Meteorological Department, (1983- 
1993) it was indicated that the average 
annual rainfall varies from 1,053.9 mm to 
1,324 mm. The rainy season lasts from 
May through October, and during 
November to April the dry season. High 
amount of precipitation usually falls 
during the months of August, September 
and October. The average annual raindays 
varies from 66.5 to 101.0 days. 
22 Slope and Topography : 
The study area has a slope gradient raging 
from 0% to more than 40%. The villages 
are usually occupying the flatter areas 
(about 0-996). Farmlands are in the 0- 
16% slope category. The mountain areas 
have slope gradient of more than 40%. 
Majority of the study area (45.4%) has a 
slope category of 0 to 2% while areas of 
more than 40% covers only about 4.7% of 
the total area. The elevation of the study 
area ranges between 80 to 560 meters 
from mean sea level (msl). 
2.4 Soils and Geology : 
Soils in the study area are residual which 
developed from granitic materials. Soil 
depth varies from shallow to very deep. 
Textural profiles are clay, loam, clay 
loam, sandy clay loam, silty clay loam, silt 
loam, fine loamy loam, sandy loam, and 
gravelly clay loam. Large areas exhibit 
color profile of very dark grayish brown to 
very dark brown over very dark grayish 
brown to dark brown. 
610 
Large portion of the study area have 
drainage characteristics of moderately 
well-drained to well-drained while small 
portions exhibit à somewhat poorly 
drained characteristic. Permeability is 
generally moderate to slow while surface 
run off is medium to rapid. Large portions 
of the area have ground water table at 
several meters all year round. Few areas 
have ground water above 1.5 meters for 2- 
3 months during the rainy season while 
the paddy fields are usually saturated for 
3-4 months in a year, 
2.5 Sources of water and 
use : 
The sources of water in the study area are 
rain, ground water, reservoir and springs. 
for majority of the villagers, rain is the 
major source of water for drinking. Each 
house ín all the villages has several big 
water tanks which are filled with water 
during the rainy season, enough to meet 
the requirement in the dry season. A 
number of reservoirs also exist in the 
study area to meet partial water 
requirement in farming and household. 
During the dry season, however, these 
reseroirs contain little water, some dried 
up, and cannot meet the water 
requirements, so most of the farmlands are 
idle in the dry season. 
2.6 Wildlife : 
A variety of wildlife are still present in the 
area. Many different species of insects 
had also been observed. Some detailed 
list of amphibians, reptiles, birds and 
mammals which can be found in the study 
area is documented by the study group. 
27 Vegetation : 
Vegetation in the villages and vicinities 
are of the types of forest and fruit trees. 
Fruit trees belonging to the family 
Leguminosae are common. Mango and 
coconut trees are also growing in some 
villages. In the northern part of the study 
area, tree plantations exist. Species of 
International Archives of Photogrammetry and Remote Sensing. Vol. XXXI, Part B4. Vienna 1996