3.3.2 Suitability Analysis
The suitability assessment was conducted by considering the land system analysis. According to Hardjowigeno et al. 2001, the suitability criteria for
paddy crops are divided into highly suitable S1, moderately suitable S2, marginally suitable S3, and not suitable N. The factors that analyzed to classify
the suitability class are limited only the constricted factors for paddy field in swamps area namely peat depth, pH, slope and salinity. Table 8 describes the
suitability criteria of the constricted factors for paddy field in swamps area. Figure 10 shows the suitability analysis framework.
Figure 10 Suitability analysis framework
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Table 8 Suitability criteria for paddy field Factors S1
S2 S3
N Peat depth cm
50 100
100-150 150-200
pH 5.5-7.0 7.0-8.0
or 4.5-5.5
8.0-8.5 or 4.0-4.5
8.5 or 4.0
Slope 3
3-8 8-15
15-25 Salinity
mmhoscm 3.5
3.5-5.0 5.0-6.6
6.6-8.0 Source : Hardjowigeno et al., 2001
Overlaying for vector datasets is conducted to obtain an aggregate of layers that determines the suitability. In vector data, the map overlay operation is
done in pairs. For a more than two layers to be overlaid, it will be taken several steps. In this research includes four map layers. So, to make its process integrated
into single process, the each vector data were converted into raster data in ArcGIS 9.3. After that by using weighted overlay processing with the same weighting for
each suitability maps, the combination layer map was produced and can be treated as single map to the next processing.
3.3.3 Accuracy Assessment
Methods for automated land features mapping are concluded with an accuracy assessment of their result Congalton, 1991. The validation sampling
points is used on this account. Accuracy assessment is done to verify the analysis and classification result using “point sampling accuracy” approach according to
“confusion matrix”. The confusion matrix summarizes the relationship between two datasets that are classification map and reference information or alternative
model. The accuracy assessment for this research use formulation below:
a. Omission Error as known as Producer’s Accuracy
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