3.1 Land use/cover classification and accuracy assessment
Our classified land-cover maps for 1985, 1998, and 2016 consisted of ‘rocks’, ‘rangeland type I’, ‘rangeland type II’, ‘water’, ‘agriculture’, ‘residences’, ‘forest’, ‘industry’ and ‘other’ thematic classes, and were produced with plausible classification accuracies (figure 2, Table 2). To increase the accuracy for the ‘agriculture’ class, lands with clean and green fallow, tilled soil and lands under crops were combined. To increase the accuracy of the ‘residences’ class, post-classification assessment was performed with a reverse comparison of the residences’ patterns; if they first appeared in 1985, they should also appear in the 1998 and 2016 maps (the assumption being that there was no reduction in residential area over time).
<Figure 2>
Table 2 shows the accuracy of maps and classes produced with a random forest classifier. The ‘agriculture’ thematic class had a high accuracy in all years. The accuracies for the ‘rangeland type I’, and ‘forest’ thematic classes were high as well. The user’s and producer’s accuracies for the ‘residences’ class varied from 0.67 to 0.80. The classes ‘rocks’, ‘other’, and ‘rangeland type I’ were the least accurate ones due to low spectral separability among these classes.
<Table 2>