GIS Application for the Determination of Geological Barriers: A Case Study of Landfill Site Selection in Songkhla Province, Thailand

  • Charusiri P. Department of Geology, Faculty of Science, Chulalongkorn University, Bangkok, Thailand
  • Ladachart R. National Research Center for Environmental and Hazardous Waste Management, Chulalongkorn University Bangkok, Thailand


The Songkhla area has been selected for geological barrier investigation due to its being the most fast-growing region of the southern Thailand. Geographic Information System (GIS) was applied to integrate several kinds of data and information involved for landfill site investigation. We subdivided our methodology into 3 steps starting with the construction of lithological barrier maps by analyzing from Lithology using space-borne image interpretation. The next step involved the making of a clay barrier map. Well data from 540 sites, and the lithological records form boreholes were queried to analyze in area of high potential barrier properties. The last step included the overlay of the clay barrier map with the lithological map to render a map of various potential geological barriers. The geological barrier map together with survey indicated 25 places in Songkhla area that have good potential geological barriers. Comparison among four existing landfill sites in the study suggests that two landfills are situated on the non-qualified geological barriers, namely, the Songkhla and the Sadao municipalities. One site in the Ban Pru municipality is located upon the medium-qualified geological barrier and the other in the Hat Yai municipality resting on the high qualified geological barrier. In this study, we also further subdivided high potential areas on the basis of slope characteristic. Then the most appropriate sites for landfills were selected including the areas in Hat Yai to Sadao and south of Saba Yoi city where good-qualified geological barriers lay underneath.