| Geoscience and Environment |
ResultsAnalysis of the 1969 land-use map suggested the kind of irrigation system used in Bayan Lepas in 1969: a system based on flooding directly from river channels without impoundment in upland reservoirs. This was an unexpected outcome of the study. A corollary of this idea is that the rice farmers got only one crop per year from this system. This suggests that conversion of land to urban uses may not have been the cause of decline in rice farming.Industrialzation proceeded first on reclaimed land. Farm families traded rice farming for work in factories and service industries. Substantial advancement in education had prepared the younger generation for non-farm occupations. Land that had been used for rice-farming was redeveloped for urban uses. This suggests that state and federal governments planned and programmed development effectively, including the broad social aspects, and that they reacted quickly to new development opportunities as they were presented. From about 1970 onwards, factories began operating in Bayan Lepas. About half the factories are sited on land that was reclaimed from coastal marshes and the sea, not on land that was formerly used for agriculture. This unexpected outcome was revealed by comparing the coastline shown in the topographic map with the coastline in the satellite images. The industrial estate is shown clearly in a false-color composite image based on red, near-infrared and infrared bands. The same composite image made it possible to identify locations in the image with surface water. This suggests that further experimentation with band combinations might improve the quality of the land-use map, experimentation that is beyond the scope of this study. The methodology adopted for this study may be appropriate only because the analyst lacked other means to compare land use in 1969 and 2003. Serious conceptual problems arise in comparing topographic maps and satellite images: topographic maps aim to define the quasi-permanent state of the landscape; satellite images capture its transient state. Topographic maps have an institutional-definitional aspect lacking in satellite images. Land-use maps based on topographic maps must therefore be conceptually different from land-use maps based on satellite image. Potential for Further WorkThis project may provide the basis for further work, such as a study of changes in land use for a sample of small areas of Penang Island.Composite images and ratio images were prepared from the ASTER dataset to help interpret the land-use map. Variations among these supporting images suggest other processing strategies with potential to improve the quality of land-use classification. Exploration of such strategies could form the basis for future work. Alternatively, a series of three LANDSAT images spread over a period of several years could be analayzed using the appropriate routines in the IDRISI package. Fieldwork would be designed to verify results from the desk analysis. Experimentation with band combinations might improve the quality of land-use map produced from such data.
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