International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, Vol XXXV, Part B7. Istanbul 2004 
  
(3) 
(5) 
(6) 
Paddy field in each satellite images is picked up using digital 
land use map. Other land use area is replaced by 0 value. 
Paddy field image of Landsat/ETM+ is classified 40 classes 
(20 May) and 60 classes by unsupervised classification 
method (ISO DATA method). We set 60 classes because 
Landsat image (26 May) is covered with thin cloud in some 
parts. We made land cover map from classified image and 
ground survey. Flooded paddy is detected by RADARSAT 
images. 
At first, we decide flooded and non-flooded paddy field from 
classified RADARSAT image (20 May) and Landsat/ETM+ 
image (16 May). Flooded paddy at 17 May and non-flooded 
paddy means flooded paddy. Next, we decide flooded and 
non-flooded paddy using classified image from two images 
and RADARSAT image (26 May). Decision role is same 
above. Finally, we decide flooded and non-flooded paddy 
using classified image from three images and Landsat image 
(5 May). 
We calculated paddy field area and flooded paddy field area 
in each district. Comparing the total of paddy field and 
statistical value, we estimate flooded paddy field area. 
4. RESULTS AND DISCUSSIONS 
4.1 Characteristics of paddy field reflectance 
  
  
  
  
14 
9 Average & 
+ standard 
n estandar [] flooded(muddy) 
120 = i O flooded(clear) 
© H Yr wheat 
2 100 A bare condition 
Ss BF aD 
8 x 
& 80 X 
= Og, x $ 4 * 
2 * * 
2 
æ 60 * i 
2 Dx 
ae 
= 40 En * 
d "| 
20 
0 
Bandi Band2 Band3 Band4 Band5 Band? 
Bands of Landsat/ETM+ 
Fig.3 Reflectance in different paddy field condition(20 May, 2002) 
00 
  
  
  
  
10 
a8 13 7 May Average & 
= 5 + standard 
— o 26.May deviation 
:- 
o 
23.0 
© 
o 
o 
x 15 
o 
2 
e 710 
o 
= 
S. 715 
2 
5 
© 
=25 
flooded flooded wheat wheat bare bare 
paddy paddy condition condition 
paddy field condition 
Fig. 4 Coefficient of back scatter in paddy field 
Characteristics of Landsat/ETM+ image (20 May) are 
shown in Fig.3. Flooded paddy fields are clearly identified 
by bands. 
Characteristics of RADARSAT images (16 and 26 May) 
are shown in Fig.4. Backscatter coefficients acquired on 26 
May are relatively higher than that on 16 May. This reason 
depends on observing sensor angle and deference of beam 
mode. Standard deviation of each land cover is higher than 
that of Landsat image. Flooded paddy field is identified to 
others. 
4.2 Relationship between the total of estimated paddy 
field area and statistical value 
Estimated paddy field sum up on district unit is very high 
  
2,000 
1,500 
1,000 
    
  
y=1.12x 
500 
Estimation of paddy fields area (ha) 
  
  
  
n=32 
r°=0.999 
0 e P 
0 500 1000 1500 ; 2000 
Statistical area (ha) 
Fig.5 Comparison between estimated paddy fields area from 
satellite data and statistical data 
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