Monitoring and Analysis of Deforestation Process using Satellite Imagery and GIS (Case Study in Myanmar)
3. Generating of Land Cover Change Map between 1989 to 1995
As a first step, the authors chose the study are is lower part of Myanmar. This are has variety of forest covers, which have been changed from 1989 to present time. The authors made field survey and collected ground truth data and reference information. The 1995 Landsat TM image and classified forest cover image were provided by JAFTA (Japanese Forest Technical Association).
As a pre-processing step for both 1989 Landsat TM and all AVHRR Time Series images, geometric correction (image registration), atmospheric correction, and sensor calibration for AVHRR image are conducted. 1995 Image has already geo-coded (Lambert Conformal Projection and resampled 50m spatial resolution) and used as reference co-ordinate system for other image processing.
To produce land cover map of 1989, we used both ISODATA classification (clustering) and supervised classification algorithms. To perform supervised classification, we create 21 training data sets made by Area Of Interest (AOIs) based on spectral differences in classified image, topographic features, previous knowledge and, applied maximum likelihood classifier.
Figure 3. Land Cover Classification of 1989
As a result, 8 classes were discriminated in this study and land cover map was produced. ISODATA CLASSIFICATION was just used to refine our training data sets. Land Cover Map
for 1995 was modified from JAFTA forest classification map. Originally classified image has 18 classes which were combined into eight classes.
Figure 4. Land Cover Area Comparision of 1989 and 1995.
Changes in land cover between the two dates (ie. 1989 and 1995) were detected by using Post classification comparison algorithm (Jensen, 1995). Pairs of classified TM image were compared pixel by pixel. Evergreen Forest, Mixed Forest and Deciduous Forest Were grouped into one class and named as Forest.
Table 2. Recode each Land cover type in two classification images
| 1989 classified Image |
Code |
1995Classified Image |
Code |
| Forest |
36 |
Forest |
37 |
| Scrub |
30 |
Scrub |
38 |
| Crop |
24 |
Crop |
39 |
| Bare |
18 |
Bare |
40 |
| Urban |
12 |
Urban |
41 |
| Water |
6 |
Water |
42 |
Table 3. Change Matrix from 1989 to 1995
| |
95 Forest |
95 Scrub |
95 Crop |
95 Bare |
95 Urban |
95 Water |
| 89 Forest |
1 |
2 |
3 |
4 |
5 |
6 |
| 89 Scrub |
7 |
8 |
9 |
10 |
11 |
12 |
| 89 Crop |
13 |
14 |
15 |
16 |
17 |
18 |
| 89 Bare |
19 |
20 |
21 |
22 |
23 |
24 |
| 89 Urban |
25 |
26 |
27 |
28 |
29 |
30 |
| 89 Water |
31 |
32 |
33 |
34 |
35 |
36 |
After re-coding and assigning in each land cover type, overlay each other and subtract 1989 land cover data from 1995 land cover data. The output values were between 1 to 36 according to their
change categories, shown in table 3.
The change categories are as follow,
-
Deforested are
(Forest to Scrub, Crop, Bare, and Urban)
- Reforested Area
(Scrub to Forest, Crop to Forest)
- Change to Scrub (Every land cover type changed to scrub except forest)
- Change to Crop (Every land Cover type change to crop except forest)
- Change to Bare (Every land cover type changed to bare except forest)
- Change to Urban (Every land cover type changed to Urban except forest)
- Land to Water (Every land type changed to water except forest)
Figure 5. Land cover Change Map between 1989 to 1995.
Table 4. Land covers changed types and area in hectares.
| |
95 Forest |
95 Scrub |
95 Crop |
95 Bare |
95 Urban |
95 Water |
| 89 Forest |
781,166.00 |
194,922.00 |
46,786.00 |
441.00 |
5,723.00 |
2,646.00 |
| 89 Scrub |
55,586.00 |
111,573.00 |
171,549.00 |
882.00 |
14,112.00 |
3,528.00 |
| 89 Crop |
24,255.00 |
95,256.00 |
878,031.00 |
3,528.00 |
18,522.00 |
18,963.00 |
| 89 Bare |
- |
1,764.00 |
38,367.00 |
882.00 |
3,528.00 |
8,379.00 |
| 89 Urban |
- |
8882.00 |
13,230.00 |
2,205.00 |
3,528.00 |
4,410.00 |
| 89 Water |
- |
3087.00 |
36,280.00 |
11,907.00 |
2,646.00 |
312,228.00 |
Table 5. Type of Deforestation and their area in hectares and percentage.
| Type of Deforestation |
Area In Hect. |
Percent |
| Forest To Scrub |
194,922 |
77.82 |
| Forest To Crop |
46,746 |
18.66 |
| Forest To Bare |
441 |
0.18 |
| Forest To Urban |
5,733 |
2.29 |
| Forest To Water |
2,646 |
1.06 |
According to the above figure, most of the deforestation caused by change forest to scrub land. 18% changes forest to Cropland and the 2.29% changes from forest to Urban / village.
