Environments transition research in yusan national park After earthquake and typhoon

Table 1. Classification result in

Year Class	1993		1996  (After the typhoon)		1999 (After the earthquake)
	Area	Percent	Area	Percent	Area	Percent
Grass	14668.47	14.09	12877.2	12.37	13238.1	12.72
Bare	6583.28	6.33	9356.33	8.99	8543.47	8.41
Wood	81105.24	77.93	79303.5	76.2	78818.6	75.73
Water (river)	1114.14	1.07	1816.08	1.74	1089.73	1.05
Cloud	605.91	0.59	-	-	2326.42	2.24
Total	104077.04	104077.04	104077.04	104077.04	104077.04	104077.04

After classification we make an accuracy assessment according to the data on the spot. The result is user accuracy is 84.62% and producer accuracy is 83.78%.

2. Land Cover Transition analysis
We respectively compare the transition from 1993 to 1996 and 1996 to 1999. The conclusions are as follow:

1. Transition analysis of 1993 to 1996
   In 1993 to 1996, most part of land cover in the Park is similar. It shows that National Park is profit for environment nursling. But it also have 3.94% land cover situation translate from woods to bare land and 2.76% translate from grass to bare land. The big fire happened during these three years may be one of the reason.
2. Transition analysis of 1993 to 1996
   In 1996 to 1999,there are 78.16% land cover didn't change in these years. But similar as 1993 to 1996, there also have a part of plant disappears. Fortunately the transition from bare land to plant is also increase at these three years.
   
   To make a comprehensive survey from 1993 to 1999, Yusan National Park goes through two huge disasters and several fire accidents. It's a pleasure to see that most part of land cover is still remaining as before. But the 3% bare land translate situation is also a big problem needed to be concerned. Consider about the distribution of transitions, we overlay geology, topography and fire accidents distribution maps. It shows that the transitions always happen around the road, river and other human activities area. Obviously human activity is a serious problem in a natural nursing region.
3. Bare ground distribution analysis
   Bare land distribution is an important factor of disaster effects in national park. We search and collect the geology, topography, stature and some land use data for bare land analysis by Geographic information Systems. We take out the bare land part from image overlap with other land use maps. The conclusions are as fig1, fig2.
   
   
   Fig 1 bare land overlap with river at 1996
   Fig 2 bare land overlap with road at 1999
   As the overlap map shows, most bare land distribute around the road and river. Compare the distribution in 1996 and 1999 we also discovered that the bare around the river are critical after typhoon at 1996. The state of affairs shows that big rain must be one critical factor of bare around rivers.
   
   
4. Disasters Sensitivity analyses
   

To take one step ahead, we search and collect some sensitivity delimit correlation researches. And harmony with GIS and Remote Sensing data, we delimit the potential disaster sensitivity region for management organization. According to the regulation of mountainside safeguard and the direction of rock formation we mark off eight kinds of basic land units. To simplify the combination we pay much attention to the gradient factor. So we combine the eight classes to five. The flow chart of environment sensibility is as fig 3 and the result is as fig 4.