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— 1723 — 
Summary of Application to: 
Land Use Alterations on Forested Watersheds 
of the Republic of China 
Lee D. Miller Q. C. Sung 
Background and Objective of the Test: The island of Taiwan is 394 kilometers long by 144 
kilometers wide at its widest point. Its total area of 35,961 square kilometers is very closely 
equal to that of one Landsat frame. Approximately one-half of this area is rugged, moun- 
tainous terrain with 62 peaks which rise abruptly from sea level to over 3,000 meters along 
its eastern margin. Mean annual precipitation in these mountains range from one to two 
meters due to the continual orographic uplift process at work on the moisture laden tropical 
atmosphere. This combination of abrupt mountainous terrain and torrential rains has given 
rise to several major river systems which headwater in the mountains along the eastern edge 
of the island and flow westward across the narrower dimension of the island. These rivers 
currently fluctuate significantly in flow but their unit hydrographs are significantly moder- 
ated by extensive tree cover on the very steep upland slopes. 
The steep nature of these upland areas has preserved them from extensive development until 
recently. Unfortunately, population pressure has now grown to the point where, when 
coupled with certain ex-official policies, extensive upland forest clearing is taking place which 
converts the forested slopes into orchards and other truck crops which grow well in the 
cooler, high altitude climates. Serious landsliding frequently occurs in areas where the forest 
cover has been removed. These same watersheds have significant hydroelectric potential if 
sedimentation processes can be controlled, and at one location a major high arch dam is near- 
ing completion. 
It is clear to resource managers in Taiwan that they are headed toward watershed disaster if 
the present course of events is continued. Military restrictions on the collection of airphotos 
and maps, especially for use in field checking, have limited the clear, objective monitoring of 
the extent and development of this problem. Gradual progress is being made toward the al- 
teration of these policies, but even if airphotos were now readily available and freely used the 
application would be hard pressed to keep up with the dynamic nature of the alteration of 
critical watershed forest cover. 
The objective of this test was to determine if the digital analysis of Landsat imagery would 
provide a mechanism for continual monitoring of the status of forest cover on these upland 
watersheds. Because of the coarser resolution of the Landsat imagery relative to low altitude 
airphotos it has been certified as unclassified and placed in the public domain by the military 
of the Republic of China. Thus, success in the fulfillment of the stated objective might pro- 
vide the basis for both a politically and technically practical monitoring system. 
The original analysis efforts reported on this topic were supported by an agency of the Gov- 
ernment of the Republic of China and by Colorado State University. The interpretation of 
the forest alteration process and its significance as outlined above are those of the first author. 
Study Site: The results described here are a reinterpretation of the results of a test applica- 
tion of the digital analysis of Landsat imagery for mapping the general land cover of the entire