N 
© 
Q 
Inclination Angle 
m Tw N 
OS s 
1 1 1 
O 
O 
O 
Oo 
À 
© 
ï 
— 
o 
1 
  
  
14 1 1 L L 1 1 1 1 
0 10 20 30 40 50 60 70 80 90100 
Proportion of Landslide 
  
Fig.9 Relationship between proportion of 
landslide areas to total area in each watershed 
and inclination angle on Minazuki district 
60 | 
  
55 
Geology 
DO 
Ov. 5 
Oo 
O 
O 
O 
A 
C, 
O 
30 Q © o 
25 1 1 1 L L 1 L 1 1 
0 10 20 30 40 50 60 70 80 90100 
Proportion of Landslide 
  
  
Fig.11 Relationship between proportion of 
landslide areas to total area in each watershed 
and geology on Yanagida district 
5.3 SHAPE FACTOR AND LANDSLIDE 
To access characteristics of each watershed , we 
introduced the factor F. F is the shape factor (A/ 
L)/L. A and L represent the area of watershed 
and length of the main river in watershed respec- 
tively. 
A/L represents averaged width of watershed . A/ 
L divided by L represents shape factor F. 
Figure 12 shows the relationship between shape 
factor F and proportion of landslide area to total 
area in each watershed. Figure 12 has very inter- 
esting results which did not realize in the past. 
When the proportion of landslide was over 70 % 
in the watershed the shape factor F increased 
sharply. 
  
  
Proportion of Landslide 
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
Fig.10 Relationship between proportion of 
landslide areas to total area in each watershed 
and geology 
  
0.14 F 
0.12 
T 
O1 
0.08 
u 
0.06 
0.04 D 
Oo 
0.02 - O Bb © 
0 L 1 1 1 
O 
O O 
o o0 
  
  
1 1 1 1 L 
  
O 10 20 30 40 50 60 70 80 90 100 
Proportion of Landslide 
Fig.12 Relationship between shape factor F and 
proportion of landslide areas to total area 
in each watershed 
5.4 THERMAL BAND DATA AND LAND- 
SLIDE 
Figure 13 and figure 14 shows the relationship 
between Band6 CCT data and the proportion of 
landslide area to total area in each watershed. 
Vertical axis of figure 13 shows CCT data of 
daytime. On the other hand, figure 14 shows 
Band6 CCT data of nighttime. Same district 
were selected on this analysis. These two figures 
has very interesting results because of opposite 
tendency appears clearly. We considered that the 
soils of landslide areas at near the ground sur- 
face has more water than that of non-landslide 
areas. At the daytime, the water in the ground 
keeps soil temperature at the low level. On the 
other hand, at the nighttime the water in the 
ground keeps soil temperature at high level. Asa 
790 
International Archives of Photogrammetry and Remote Sensing. Vol. XXXI, Part B4. Vienna 1996