which included late transplanted rice and direct seeded rice.
By using this algorithm, 85 percent of late transplanted rice
fields were separated from direct seeded rice fields.
Results
Spatial Distribution of Land Use / Land Cover
Ten land-use/land-cover classes were identified using spectral
matching techniques using
MODIS
temporal imagery and Land-
sat-8 (Plate 1). With average rainfall in the order of 600 mm/
annum and large areas under rainfed cropping, canal irriga-
tion from Tungabhadra Dam provides insufficient irrigation
to grow rice. The total irrigated area accounts for 287,993 ha
(Table 2). The important rice growing taluks (administrative
units) are Manvi and Sindhanur where a large area is irri-
gated under rice. The adoption of direct rice seeding is due to
shortage of labor, and it is a new phenomenon and expanding
along with transplanted rice cultivation which is essentially
large in extent. The use of temporal
RISAT-1
imagery helped
in identifying how rice was planted (direct seeded rice or
transplanted) and also ascertaining time of planting (early or
late transplanting). This information can be used to schedule
irrigation and estimate harvest dates for each type of practice.
It is clear that the head end of the canal has a larger extent
of transplanted rice than the tail end in Manvi and Sindha-
nur with irrigated mixed crops. Rainfed croplands occupy
the largest area of 351,895 ha in Raichur District. Pigeonpea
mixed with a cereal crop like sorghum is one of the important
and large cropping systems in the taluks of Lingsugur and
Raichur. Rangelands and shrublands are comparably large
which can be potentially used for rainfed agriculture.
Spatial Extent of Direct Seeded Rice and Transplanted Rice
Rice is a major crop in Raichur District, covering 130,343 ha in
2013, out of which transplanted rice covered 117,401 ha and
direct seeded rice 12,942 ha. The major rice area is located in
Manvi and Sindhanur taluks which are irrigated, depending on
ground water availability and rainfall. Of the total rice area, 52
percent is early transplanted rice, 38 percent is late transplant-
ed rice, and only 10 percent is direct seeded rice (Table 2 and
Plate 1). Variations within the direct seeded field are difficult
to identify due to the temporal deficit of the image acquisition.
Accuracy Assessment
The classification accuracies obtained from the 122 indepen-
dent ground data observation data points for the year 2014
were gathered from the study area (monsoon season). Accuracy
assessment was done using error matrix, a multi-dimensional
table in which the cells contain changes from one land-use
class to another. The statistical approach of accuracy assess-
ment consists of different multi-variate statistical analyses
(Congalton and Green, 1999; Jensen, 1996). The error matrix ac-
curacy varied from 75 percent to 92 percent across six cropland
areas. However, it must be noted that rice classes did not mix
with other classes. Overall, accuracy was 82 percent and kappa
was 0.78. So the uncertainty of about 18 percent is due to the
inter-mix among the other land-use/land-cover classes (Table 3).
Comparison with National Statistics and Other Studies
Statistics on taluk-wise rice area in Raichur District was ob-
tained from the Bureau of Economics and Statistics, Govern-
ment of Karnataka State, India. This data was used for com-
paring
RISAT-1
, Landsat-8, and
MODIS
-derived statistics. A high
correlation was found (Figure 4) between the two sources of
information on rice cultivation in the district.
T
able
2. E
stimated
A
rea
U
nder
D
ifferent
L
and
U
se
/L
and
C
over
(LULC)
C
lasses
in
R
aichur
D
istrict
LULC area
Area (ha) %
01. Irrigated-conjunctive-DS-rice
12,942 1.5
02. Irrigated-conjunctive-early TP-rice
67,418 8.0
03. Irrigated-SW-late TP-rice
49,983 5.9
04. Irrigated-conjunctive-SC-mixed crops
157,650 18.7
05. Rainfed-SC-pigeonpea/mixed crops
122,778 14.6
06. Rainfed-mixed crops/fallows
229,117 27.2
07. Rangelands/shrublands
152,442 18.1
08. Barren lands/shrublands/forests
37,060 4.4
09. Water bodies
9,241 1.1
10. Settlements
3,695 0.4
Total
842,326
T
able
3. A
ccuracy
A
ssessment
U
sing
G
round
S
urvey
D
ata
(T
wo
D
imensional
E
rror
M
atrix
)
Classified data
Reference data
Reference row total
Classified totals
Producers accuracy
Users accuracy
Kappa accuracy
01. Irrigated-conjuctive-
DS-rice
02. Irrigated-conjunctive-
early TP-rice
03. Irrigated-SW-late
TP-rice
04. Irrigated-conjunctive-
SC-mix
05. Rainfed-SC-
pigeonpea / mixed crops
06. Rainfed-mixed crops/
fallows
07. Other LULC
01. Irrigated-conjuctive-DS-rice
3
0
1
0
0
0 0 3
4 100% 75% 74%
02. Irrigated-conjuctive-early TP-rice
0
12
1
0
0
0 0 13 13 92% 92% 91%
03. Irrigated-SW-late TP-rice
0
0
7
1
0
0 0 9
8 78% 88% 87%
04. Irrigated-conjuctive-SC-mix
0
0
0
22
2
1 0 24 25 92% 88% 85%
05. Rainfed-SC-pigeonpea/mixed crops
0
0
0
1
19
2 1 27 23 70% 83% 78%
06. Rainfed-mixed crops/fallows
0
1
0
0
4
30 1 37 36 81% 83% 76%
07. Other LULC
0
0
0
0
2
4 7 9
13 78% 54% 50%
Total
3
13
9
24 27 37 9 122 122 84% 80% 77%
PHOTOGRAMMETRIC ENGINEERING & REMOTE SENSING
November 2015
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