important crops besides rice production in Taiwan. 
With the expanding of Betel nut planting area and the annual raise of 
productivity, the increasing concern about the soil and water conservation impact has 
become one of the major environmental issue. Among these figures, the Betel nut’s 
planting area on slopeland has exceeded 40 thousand hectares. Pin-Ton, Chia-Yi, and 
Nanto are three major suppliers of Betel nut production area in Taiwan, which 
inherited the tendency to totally replace the fruit or tea farm. This study examined the 
ground truth by classified Landsat TM image and surface DGPS operation at Shu-Li 
river watershed in Nanto county. A GIS database was composed from geographic, 
geologic, hydrologic, and social-economic data of this watershed area to assist the 
extraction of Betel nut crop growth characteristics for accurate image classification. 
The output result can supply the information to watershed management institute. 
One of the focused issue in this study was satellite image classification. One to 
five thousand scaled aerial photo was used as the reference information for Landsat 
TM image classification accuracy examination. Ground surveying by the aided of 
GPS and Differential GPS (DGPS) was performed to extract the surface soil erosion 
simulation parameters. 
Background 
Shu-Li river watershed locates at the center of Taiwan, consists an area of 7400 
hectare. The elevation is between 373m and 1390m. Classified Landsat TM image 
shows on figure 1. There are three reservoirs with power plants, and one amendment 
pond in this study area. Warm Climate composes the annual average temperature 
around 21 degree centigrade. 
Bamboo, fruit trees and Betel nut are three dominated vegetation in this area. 
Among that cash crop growth, because of the suitable temperature and rainfall 
condition, as well as the ease for harvest and high economical return, Betel nut has 
become the majority crop in this watershed. The expanding of Betel nut growth area 
created several serious problems for the Shu-Li River watershed. From on-site 
research, Chen (1994) pointed out the Betel nut is not a good land cover vegetation for 
soil conservation practice. 
Farming activity on slope land developments not only enhance the water 
evaporation, increase runoff and soil erosion, but also lower the ground water level 
and degrade the nature environment. At the first growing stage of Betel nut crop 
growth, the huge slope land development could cause significant damage for soil and 
water conservation and raise soil erosion rate. It's also been reported for the micro 
climate changes due to the over development of natural forest. 
USLE & RUSLE are the most important model in soil erosion research. In USLE 
model application, Hu(1993) researcher estimated the hydrology and erosion impact 
from Betel nut farming at Lien-Hua-Chi area. In RUSLE model application, 
Hung(1992) and Chui (1992), demonstrated the process to estimate soil erosion 
for a specific watershed. In showing the capability of combining USLE and RUSLE 
with GIS application, Lua(1990) and Cheng(1994), simulate soil erosion for Chi-Lung 
River Basin and used GIS to evaluate the impact to erosion due to large area slope 
land development. As proved, USLE & RUSLE model are empirical model from 
field experiments, which restrain the real world application. In order to accurate 
estimate the soil erosion from that model, it is necessary to extract sufficient 
parameters for model calibration and validation. Fang (1993) and Wu(1994) has 
examined the parameter for Taiwan area from a series of field experiments and the 
comparison of model prediction result. In worldwide, there are also many researches 
in theory or application experiments by the assist of GIS linkage with soil erosion . 
prediction, such as “A Land information system for soil erosion control planning”, to 
specify ownership and location of parcels rates of soil erosion, and in order to 
establish priorities for controlling soil erosion etc.(Ventura S.J., 1988), “Revised 
universal soil loss equation” to know the development of RUSLE From USLE 
(Renard K.G., 1991), “Using the erosion production impact calculate (EPIC) model 
to estimate the impact of soil erosion”, to know the model and to simulation the soil 
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International Archives of Photogrammetry and Remote Sensing. Vol. XXXI, Part B7. Vienna 1996