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le 
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A 4 A 
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CIshika ^ A 
we. 7 
o fe, 
Fig.1 Landslide areas in Hokuriku District 
Dotted symbols in the figure is landslide areas 
study elevation data is key data to evaluate the 
landslide areas. In the past study we had made the 
elevation data from 1/25000 scale maps with a lot 
of works. For example elevation data of 
30m*30m mesh size for a sheet of 1/25000 scale 
map was made by four or five persons with two 
weeks. The 1st July in 1995 however, Geo- 
graphic Survey Institute of Japan published 
DEM of 50m*50m mesh size for the pilot areas. 
We adopted DEM data instead of hand made el- 
evation data. Figure 3 shows the map of elevation 
originally made by us. Mesh size is 30m * 30m. 
Figure 4 shows the map of elevation made from 
DEM which has 50m * 50m mesh size. Two 
figures have similar condition. It is shown that 
DEM of 50m * 50m mesh size data is able to 
extract watershed areas. We convert DEM of 
50m * 50m mesh size to 30m * 30m mesh size by 
     
  
f 
Sosogi 
  
    
  
  
  
  
  
Yanagida 
  
  
  
  
  
Fig.2 Investigation areas for landslide. 
Each square is about 10km long 
by 10km wide 
using bi-linear interpolation method. Inclination 
angle was computed from interpolated elevation 
data. 
3.2 SATELLITE DATA 
Ground surface temperature and NVI was used to 
evaluate Landsat TM data. It is well known that 
Landsat TM band 6 data (we call it thermal band 
Table.1 Thematic maps and Landsat TM data 
  
Thematic Maps 
Landslide Map 
Geological Map of Ishikawa 
Elevation Data 
  
Observed Date (Rainfall of a week before) 
  
  
  
  
  
  
6 April 1989 (0.0mm) 
Landsat TM Data 24 May 1989 (3.5mm) 
9 April 1990 (70.0mm) 
6 Nov. 1991  (34.5mm) 
21 May 1991 (-----mm) night-time 
787 
International Archives of Photogrammetry and Remote Sensing. Vol. XXXI, Part B4. Vienna 1996