DOI: 10.14457/tu.the.2020.839
title: Economic expansion and land use change in Thailand: an environmental impact analysis using computable general equilibrium model

description: This study aims to develop the Computable General Equilibrium (CGE) model to simulate the impacts of economic expansions on land-use changes and examine the subsequent environmental impacts. First, the SAM table is constructed from the input-output table. Then, the study analyzes two levels, consisting of the national and regional models. Specifically, the regional model focuses on the special economic zone of Eastern Economic Corridor (EEC), covering Chonburi, Rayong and Chachoengsao provinces. The nested structure of the CGE model describes the spatial redistribution mechanism and selects production factors between agricultural land and urban areas. Therefore, the study consists of the following important results.(1) Demand changes: land price change is negatively related to change in demand for land. Also, changes in urban land demand significantly affect both variables than changes in rural land demand. As for the national level, the wholesale and retail trade sectors are greatly affected by changes in urban land demand. In the case of the EEC area, demand for urban land most affects the construction sector because of infrastructure investment.(2) Productivity improvement: improving the land utilization coefficient reduces the demand and rent for rural land areas because the land use capability has increased; on the other hand, the demand for urban land has slightly increased. However, better efficiency of land utilization in all simulations still leads to a greater economic value-added.(3) Environmental impact: increasing farming and urban areas lead to higher solid waste, water pollution, and air pollution. Specifically, the 1% increase in the urban area at the national level can increase pollution as follows: the solid waste increase by 0.051%, water pollution ̶ indicated by BOD ̶ increase maximum by 0.053%, and air pollution ̶ indicated by the volumes of CO2, N2O, NOx, CH4, and SO2 ̶ increase within the range of 0.039% - 0.053%. Whereas the increase in land efficiency leads to the low intensity of environmental impacts, urban solid waste increased by only 0.038%, and water and air pollution increased maximum by 0.041%. In the case of the EEC area, because the area is less than the nationwide, the fewer production quantities can be produced, the less the environmental impact. Overall, it has increased pollution by an average of 0.01% in urban areas. The construction sector also continues to have the greatest influence on environmental problems in the EEC.Therefore, we provide the following policy implications: (1) The government should legislate policies that improve land efficiency in provinces apart from Bangkok, especially special economic zones. The requirement is, for example, the determination of the land-use density trade-off green areas. (2) The waste disposal tax and the wastewater treatment fee need to be improved and considered to have a broader base of taxable units to make awareness society of the environmental problems. Also, the government needs to upgrade more air pollution control measures.