Table 1 (below) compares land use in 1969 and 2003. The table shows that by 2003 all of the rice fields have changed use and the land area has increased by reclamation of marshland and the intertidal zone. The airport has more than doubled in size.
The estimated residential-commercial area in 1969, including infrastructure but not including the airport was 0.75 km2. This estimate is not shown in the tables below. (See Buildings for the calculation.).
A weakness of the methodology is that the topographic map shows institutional features,such as the airport perimeter, while the satellite image does not. (The analyst infers a perimeter based on roads and other features plus a modern road map.) Conceptually, the "drains" and the class "rice-fields" might also be considered institutional, since they might not be identifiable as such in a satellite image.
The land-use map for 2000 illustrates the importance of the definitional and conceptual aspects of interpreting the maps and the satellite images. "Other land" in 2003 has a sub-class "other" that was difficult to interpret and provisionally classed as "water on or near the surface" (ponds, rivers, drains, and waterlogged soil). Further analysis, assisted by infrared imagery, seemed to confirm this classification. The total area of land affected by surface water was estimated was 9.1 km2 (Table 2, below), an area greater than the combined area of rice-fields and marshland in 1969, 7.4 km2. This result appears paradoxical unless the institutional-definitional aspect of "rice-field" and "drains" is considered.
Topographic maps aim to define the quasi-permanent state of the landscape, while satellite images capture its transient state. Topographic maps have an institutional-definitional aspect lacking in satellite images. Land-use maps based on topographic maps may therefore be conceptually different from land-use maps based on satellite images.
