Urbanization linked with past agricultural landuse patterns in the urban fringe of a deltaic Asian mega-city: a case study in Bangkok

Urban sprawl areas as mixtures of urban and rural landuses are being created increasingly rapidly in the suburbs of the mega-cities located on Asiaʹs river deltas. These landuse changes are causing serious environmental problems and dynamic urban growth controls are urgently needed. We examined landuse changes in the suburbs of Bangkok, and focused on the landform transformation that is inherent on deltas where the landuse is shifting from paddy fields to urban dwellings. The research was conducted through aerial photograph interpretation and field measurements. GIS was used for data analysis. We confirm that the present pattern of urban landuse has been profoundly influenced by past agricultural landuses, which in turn were adapted to the natural local environment. Areas subject to rice plantations with linear canal systems are occupied by townhouses, whereas areas subject to paddy fields with irregular canal systems are occupied by slum-type housing. Transect surveys indicate that the local people have responded to flooding expertly through artificial landform transformation. There was a statistical association between landlevel and landuse type. The volume of landform transformation that has occurred over the last half-century was calculated at 3.2 × 107 m3, equivalent to 64 km2 of area flooded to an average depth of 50 cm. Thus, landuse change has both horizontal and vertical components, which cannot be separated from each other. From these results, it is clear that past patterns of agricultural landuse and landform transformation are keys to effective landscape planning for mega-cities on the deltas of Asia.