Detection and Monitoring of High Economic Return Crop 
Growth Expanding for Watershed Area at Central Taiwan 
Tien-Yin Chou , Associate Professor,Dept.,of Land Management , Fen Chia University, Taichung, Taiwan 
Mei-Ling Yeh » Chih-Heng Liu » Graduate Assistant, Grad. Inst. of Land Management , Fen Chia University, 
Taichung, Taiwan 
Commission VII, Working Group 2 
Keywords : Land-use » Landsat » Classification » Vegetation 
Abstract 
The slopeland development which attracting the farmers to plant the Betel nut 
crop in order to get higher economic return has expanded widely in recent year 
especially at Central Taiwan area due to the mild weather and fertilized soil. 
This research detected and monitored the land development changes at Shu-Li 
River watershed that locates at central Taiwan and consists of three reservoirs and one 
amendment pond. The study used Geographic Information Systems (GIS) , 
Remote Sensing (RS), Global Positioning System (GPS) techniques, and Universal 
Soil Loss Equation (USLE) to estimate the soil erosion caused by Betel nut 
expanding. By identifying the internal and external cost for this watershed area, the 
non-market numerical economic cost and benefit value for the influence by this high 
economic return crop can be examined. This survey can replace the traditional on-site 
surveying with time and labor consuming and can provide a decision reference for 
local government for watershed management. 
Introduction | 
Slopeland counts for two thirds of the total land in Taiwan. Due to the rapid 
economic growth, the flat areas were full developed as urban land use and reduced the 
arable land area. There is a tendency to expand the development toward slopeland or 
even mountain area. From economical incentives, the result's impact has caused the 
suffering and degrading of the environment. Illegal or over-limited land use at sloped 
land area are a common phenomenon at Taiwan area and danger the sustainability of 
sensitive slope land. 
The concentrated precipitation from May to August brought almost 80 percent 
of the annual rainfall amount for Taiwan island. Along with the natural geologic 
steep relief for most river watershed, it is significant important for soil conservation 
and water preservation. In recent years, Betel nut has become one of rapid expanding 
crop growth material at many slopeland areas. The geographically over-limited Betel 
nut planting created high revenue for the farmer and satisfied the consumer. The 
negative impact to the environment and water resources can never be ignored. 
According to recent Taiwan Agricultural Yearbook, the Betel-nut planting area 
has reached totally 44671 hectare, which is over 1 percent of the total island area. The 
output income from Betel nut production in 1971 was 78,835 thousand dollars, and it 
reached to 10,310,025-thousand dollars in 1993. This output becomes the most 
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International Archives of Photogrammetry and Remote Sensing. Vol. XXXI, Part B7. Vienna 1996