According to the result of classification is noted that more classes than those of interest swamps and not swamps. Next, the pixels of each input image were
reclassified to get the swamps and not swamp classes. Based on the Ramsar Convention 1971 that swamps is one of the wetland forms that included
in the non-forested peat lands so for Image acquisition on 15 April 2000, swamps areas were formed from bare land, inundation area, shrub and paddy field. The
others were formed as not swamps areas. Meanwhile for Image acquisition on 16 May 2006, swamps areas were formed from bare land, inundation area, shrub,
mangrove and paddy field. The others were formed as not swamps areas.
4.1.4 Spatial Analysis
Spatial analysis was done by using threshold value for each parameter LST, NDWI and reclassification from supervised classification result. For the
supervised classification result, the swamps area were extracted from the classified image by using simple logic calculation to form a binary-image with the
swamps class assigned a value of 1 and all not swamps class to a value of 0. The simple logic for each images are as follows LOGIC 1:
• For image acquisition on 15 April 2000
If i1=bare land or i1=inundation area or i1=shrub or i1= paddy field then 1 else 0
• For image acquisition on 16 May 2006 If i1=bare land or i1=inundation area or i1=shrub or i1=mangrove or
i1= paddy field then 1 else 0
where : i1 = Land Cover Type
0 = Not Swamps Area 1 = Swamps Area
The result of image classification for image acquisition on 15 April 2000 and image acquisition on 16 May 2006 respectively after reclassify into 2 classes:
swamps and not swamps can be seen in Figure 18 and Figure 19. The percentage area of swamps and not swamps for each image can be seen in Table 15.
41
Figure 18 Swamps classification for image acquisition on 15 April 2000
Figure 19 Swamps classification for image acquisition on 16 May 2006
Table 15 Percentage of swamps and not swamps area for each image
Image Acquisition Area
Swamps Not Swamps
15 April 2000 84
16 16 May 2006
80 20
42
Information extraction using threshold value is applied to single-layered images, usually after their enhancement. The threshold values for each satellite
imageries can be seen in Table 16. The threshold value applied in this research, considered range value minimum – maximum value for each parameter. NDWI
value more than zero means the open water features in the area. Meanwhile, swamps area is a lowland region saturated with water. According to the definition,
so can be assumed that the swamps area have the water content less than open water. It indicates that swamps area had the NDWI equal or less than zero.
The threshold value of LST considered the range value of average swamps temperature in Banyuasin Regency about 23
o
C – 33
o
C. The other value of swamps temperature is based on the assumption that more saturated area has the
lower temperature. A threshold value in Table 16 was used to determine swamps area from
NDWI and LST to form a binary-image with the swamps class assigned a value of 1 and not swamps class assigned a value of 0. The method is an “if-then-else”
logic calculation through a band spectral signature analysis. A simple logic statement can easily extracted swamps area from image owing to its much simpler
signatures than those of original image. A simple logic statement can easily extracted swamps area from image owing to its much simpler signatures than
those of original image. The logic calculation can be expressed as follows LOGIC 2:
If i1=minimum of LST value and i1=maximum of LST value or i2=minimum of NDWI value and i2=maximum of NDWI value then 1
else 0
where : i1 = LST Values
i2 = NDWI Values 0 = Not Swamps Area
1 = Swamps Area
43
Table 16 Threshold in swamps area analysis
Threshold Para-
meter Image
Acquisition Range
Threshold Values
I LST
o
C 15 April 2000
16 May 2006 2 to 35
3 to 37
23 to 33 23 to 33
NDWI 15 April 2000
16 May 2006 -0.37 to 0.61
-0.66 to 0.38
-0.43 to 0 -0.43 to 0
II LST
o
C 15 April 2000
16 May 2006 2 to 35
3 to 37
23 to 33 23 to 33
NDWI 15 April 2000
16 May 2006 -0.37 to 0.61
-0.66 to 0.38
-0.35 to 0.1 -0.35 to 0.1
III LST
o
C 15 April 2000
16 May 2006 2 to 35
3 to 37
12 to 20 12 to 20
NDWI 15 April 2000
16 May 2006 -0.37 to 0.61
-0.66 to 0.38
-0.4 to 0.2 -0.4 to 0.2
Swamps area includes inundation area, bare land, paddy field, shrub and mangrove
Finally, swamps area and not swamps area distribution were obtained from overlaying process between the results of LOGIC 1 and LOGIC 2. The result
probability for the final result in swamps identification can be seen in Table 17.
44
Table 17 Result probability for each threshold values
Thres hold
Probability LST
o
C NDWI Land
Cover Result
I 1
23 to 33 -0.43 to 0
Bare land, Paddy Field, Shrub, Inundation Area, Mangrove
Swamps 2
23 to 33 -0.43 to 0
Water bodies, Settlement, Cloud, Cloud shadow, Fish
pond, Forest Not
Swamps 3
12 to 22 -0.43 to 0
Bare land, Paddy Field, Shrub, Inundation Area, Mangrove
Not Swamps
4 12 to 22
-0.43 to 0 Water bodies, Settlement,
Cloud, Cloud shadow, Fish pond, Forest
Not Swamps
5 23 to 33
0.1 to 0.4 Bare land, Paddy Field, Shrub,
Inundation Area, Mangrove Not
Swamps 6
23 to 33 0.1 to 0.4
Water bodies, Settlement, Cloud, Cloud shadow, Fish
pond, Forest Not
Swamps
II 1
23 to 33 -0.35 to 0.1
Bare land, Paddy Field, Shrub, Inundation Area, Mangrove
Swamps 2
23 to 33 -0.35 to 0.1
Water bodies, Settlement, Cloud, Cloud shadow, Fish
pond, Forest Not
Swamps 3
12 to 22 -0.35 to 0.1
Bare land, Paddy Field, Shrub, Inundation Area, Mangrove
Not Swamps
4 12 to 22
-0.35 to 0.1 Water bodies, Settlement,
Cloud, Cloud shadow, Fish pond, Forest
Not Swamps
5 23 to 33
0.1 to 0.4 Bare land, Paddy Field, Shrub,
Inundation Area, Mangrove Not
Swamps 6
23 to 33 0.1 to 0.4
Water bodies, Settlement, Cloud, Cloud shadow, Fish
pond, Forest Not
Swamps
III 1
12 to 20 -0.4 to 0.2
Bare land, Paddy Field, Shrub, Inundation Area, Mangrove
Swamps 2
12 to 20 -0.4 to 0.2
Water bodies, Settlement, Cloud, Cloud shadow, Fish
pond, Forest Not
Swamps 3
23 to 33 -0.35 to 0.1
Bare land, Paddy Field, Shrub, Inundation Area, Mangrove
Not Swamps
4 23 to 33
-0.35 to 0.1 Water bodies, Settlement,
Cloud, Cloud shadow, Fish pond, Forest
Not Swamps
5 23 to
33 0.1-0.4
Bare land, Paddy Field, Shrub, Inundation Area, Mangrove
Not Swamps
6 23 to
33 0.1-0.4
Water bodies, Settlement, Cloud, Cloud shadow, Fish
pond, Forest Not
Swamps
45
For image acquisition on 15 April 2000, in Figure 20 can be seen swamps area distribution in area of interest under threshold value I. Figure 21 shows swamps
area distribution under threshold value II and Figure 22 shows swamps area distribution under threshold value III.
Figure 20 Swamps distribution of image acquisition on 15 April 2000 under threshold I
Figure 21 Swamps distribution of image acquisition on 15 April 2000 under threshold II
46
Figure 22 Swamps distribution of image acquisition on 15 April 2000 under threshold III
The percentage of swamps and not swamps area distribution for each threshold values for image acquisition on 15 April 2000 can be seen in Table 18.
Table 18 Percentage area of swamps and not swamps for image acquisition on 15 April 2000
Threshold Value Area
Swamps Not Swamps
I 85.2 14.8
II III
87.7 84.6
12.3 15.4
The threshold value I resulted the swamps area of 85.2 and not swamps area of 14.8. The threshold II resulted the swamps area of 87.7 and not
swamps area of 12.3 and for threshold value III, the swamps area covered 84.6 and not swamps area covered 15.4 from whole area of interest.
The threshold values II had the higher percentage swamps area of 87.7. It indicates that 87.7 from area of interest had the LST value around 23
o
C to 33
o
C, NDWI value around -0.35 to 0.1 and land cover type including bare land,
inundation area, shrub and paddy field.
47
For image acquisition on 16 May 2006, in Figure 23 can be seen swamps area distribution in area of interest under threshold value I. Figure 24 shows
swamps area distribution threshold value II and Figure 25 shows swamps area distribution threshold value III.
Figure 23 Swamps distribution of image acquisition on 16 May 2006 under threshold I
Figure 24 Swamps distribution of image acquisition on 16 May 2006 under threshold II
48
Figure 25 Swamps distribution of image acquisition on 16 May 2006 under threshold III
The percentage of swamps and not swamps area distribution for each threshold values for image acquisition on 16 May 2006 can be seen in Table 19.
Table 19 Percentage area of swamps and not swamps for image acquisition on 16 May 2006
Threshold Value Area
Swamps Not Swamps
I 75.2 24.8
II III
70.0 15.1
30.0 84.9
The threshold value I resulted the swamps area of 75.2 and not swamps area of 24.8. The threshold value II resulted the swamps area of 7.0 and not
swamps area of 30.0 and for threshold value III, the swamps area covered 15.1 and not swamps area covered 84.9 from whole area of interest.
The threshold values I had the higher percentage swamps area of 75.2. It indicates that 75.2 from area of interest had the LST value around 23
o
C to 33
o
C, NDWI value around -0.35 to 0.1 and land cover type including bare land,
inundation area, shrub, mangrove and paddy field. In the next analyzing, change detection was done by using the result of
image acquisition on 15 April 2000 under the threshold value II and image
49
acquisition on 16 May 2006 under the threshold value I as the result with the higher percentage than others. The swamps area distribution using image
acquisition on 16 May 2006 had smaller area proportion than image acquisition on 15 April 2000. It’s caused by the acquisition date of the image influencing the
temperature and water distribution in whole area of interest. It implies to the large area of swamp distribution. Swamps distribution obtained from image acquisition
on 15 April 2000 under threshold II analyzing have the area around 6,389 km
2
and swamps area distribution obtained from image acquisition on 16 May 2006 under
threshold I had the area is around 5,493 km
2
.
4.2 Accuracy Assessment
