Agriculture Reference
In-Depth Information
Fig. 4.8
Supervised land classification of satellite images for years 1992, 2002, and 2005
Table 4.1
Land
use classifications of 1992, 2002, and 2005 for AOI
Number of Pixels
Area (ha)
1992
2002
2005
1992
2002
2005
Paddy
8,337
8,564
7,700
750.33
770.76
693
Vegetation
5,970
4,269
6,656
537.3
384.21
599.04
Mature tea
22,808
24,103 21,209
2,052.72
2,169.27
1,908.81
Young tea
5,082
4,538
8,709
457.38
408.42
783.81
Construction
4,944
6,825
4,397
444.96
614.25
395.73
Water body
244
1,266
894
21.96
113.94
80.46
Total
47,385
49,565 49,565 4,264.65 4,460.85 4,460.85
and decreased to 693 ha in 2005. Reduction of total pixels of paddy field might be
due to land filling, heap up of mining ore or fallowing of paddy fields. However, to
reach a proper conclusion, high resolution satellite image like LISS-IV is required.
Fluctuation in water bodies over the period might be due to temporal changes of
weather. However, an area of 21.96 ha which was recorded in 1992, represents the
perennial water bodies and the subsequent fluctuations are due to accumulation of
water in seasonal water bodies.
Construction sites, which were characterized by open land with or without man-
made structures, were observed. This area for the year 1992 is 444.96 ha. However,
it shows significant increase over a period of 10 years and its extent in 2002 was
observed to be 614.25 ha. Actual construction site, land clearing for agricultural
activities and pruning of existing tea fields can yield similar reflectance. Therefore,
the effect can be a short-term influence. However, further studies are required to
explain the anomaly in 2005 (Table
4.1
).
Total pixel area belonging to tea cultivation is 2,510.1, 2,577.69, and 2,692.62 ha
in 1992, 2002, and 2005, respectively. However, according to 2005 census report,
total tea extent in this division is 4,726 ha. AOI is only a fraction of Ratnapura divi-
sion and therefore supervised classification overestimated the tea extent. Similar
