Geography Reference
In-Depth Information
Table 6.6 Accuracy assessment of pre-classification change detection approach results
Initial LANDSAT-MSS-data (1975)
Final LANDSAT-TM-data (2007)
Total/possible
(1)
(2)
(3)
No change (1)
230
21
7
258
Natural vegetation to bare areas (2)
13
155
4
172
Bare areas to cultivated areas (3)
3
8
132
143
Other (4)
4
16
7
27
Total
250
200
150
600
Overall pre-classification change detection accuracy = 230 ? 155 ? 132/
600 = 86 %
changes (e.g., cultivated areas to bare areas, etc.). Therefore, the class ''other'' was
added for purposes of accuracy (i.e., the initial data), could be used to can rep-
resent the rest of the possibilities of the LULC-alternations between the two
compared dates. The overall accuracy was 86 %.
This method would be useful for assessment of the accuracy of change
detection mapping, where it is almost impossible to gather ground and/or reference
data for the relatively old dates (Table
6.6
).
6.3.2 Post-Classification Results
Measure of changes/quantity. Post-classification approach results (Figs.
6.12
and
6.13
, Tables
6.7
and
6.8
) were more obvious and detailed rather than those
resulting from a pre-classification approach (see
Sect. 6.3.1
). The total change in
the whole study area (5,062,082 ha, 100 %) between 1987 and 2007 was about
5,027,722 ha (99.32 %). Areas recording no changes were about 34,360 ha
(0.68 %). The greatest changes (Table
6.7
, Fig.
6.12
) were in the artificial surfaces
classification with a total change of 83.16 %, in which 38.77 % was changed to
cultivated areas and 35.08 % transformed to the bare areas class; natural vegeta-
tion with 68.33 %, where 42.95 % changed to cultivated areas and 24.00 % to bare
areas; natural water-bodies with 21.45 %, where 13.34 % changed to cultivated
areas; followed by cultivated areas with 17.86 %, of which about 6 % was
changed to each of the other two classes, i.e., natural vegetation and bare areas.
The bare areas class showed the most stability over time with 13.89 % change.
Three general trends in LULC-changes were found: negative values/loss, in which
the represented classes were artificial surfaces (-64.81 %) and natural vegetation
(-43.22 %); neutral value/stable, in which the represented class was bare areas
(0.23 %); and positive values/gain, which included cultivated areas (+35.49 %)
and natural water-bodies (+6.66).
Each LULC-class has three general trends (Table
6.8
): (1) The stable trend, that
represents the unchanged part of an individual class (e.g., cultivated areas:
1,080,987 ha) over the time period; (2) The positive trend (the horizontal direction
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