BANGKOK’S URBAN SPRAWL: LAND FRAGMENTATION AND CHANGES OF PERI-URBAN VEGETABLE PRODUCTION AREAS IN THAWI WATTHANA DISTRICT

Urban sprawl is a global phenomenon that has transformed the surrounded agricultural lands over the fringe of megacities. Vegetable production areas in the Bangkok’s peri-urban area have been at risk for changing due to the influences of urbanization. This study on the prime vegetable production areas in Bangkok, Thawi Watthana district, aimed to: 1) understand and determine the land use changes to these areas, 2) clarify the landscape configurations of these areas to assess landscape fragmentation, 3) discuss and recommend land use planning policies and measures to conserve the existing peri-urban agricultural landscape. A geographic information system (GIS) database and three thematic map layers (land use, waterways, and roads) were created and analyzed to clarify land use proportions, changes in the vegetable production areas, and the land configurations during different periods from 1976 to 2015. The Spatial Analyst in the ArcGIS 10.3 program was utilized. The results showed that vegetable production areas in the district decreased at a rate of 20.38 ha/y, even though the district was designated as an agricultural area in the Bangkok’s land use planning policies. The fragmentation of the vegetable production matrix (indicated by patch number, patch density, and mean patch size) increased due to the immediate effect of the expanded road network construction and due to a later consequence of the contiguous roadside urban development. The remaining vegetable production areas were mostly away from the primary road leading to the Bangkok center city. The monitoring system on the fragmentation of agricultural lands is essential as a database to find suitable measures to control urban sprawl in various cities.