Spatial planning for secured landfill using an expert geographic information system

Abstract

This study aims at developing an Expert Geographic Information System for secured landfill sites analysis called as EGIS. The EGIS is a package tool of an integrated Geographic Information System (GIS), Expert System (ES), Analytic Hierarchy Process (AHP), and Visual MODFLOW model. GIS represents a spatial data, ES represents a knowledge base about secured landfill siting, AHP applies for ranking of candidate sites, and the Visual MODFLOW model is used as a tool for predicting the possible groundwater impacts from the landfill site. The developed EGIS was applied to identify the preferred site for secured landfill in Khon Kaen province, Thailand. Prior to applying GIS, criteria for secured landfill were formulated by compiling criteria of US.EPA, MOInd and PCD. The formulated criteria are consisted of 23 criteria. The selected criteria for Khon Kaen Province inputted by users through ES, 16 criteria were used as the input to GIS model. The result of GIS models analysis showed that there were eleven candidate sites for secure landfill. The candidate sites were then ranked as top five sites by using AHP method based on fifteen factors considered from the selected criteria including 2 social factors. The top five candidate sites with AHP ratio of 0.322, 0.307, 0.226, 0.203 and 0.188 for site 3 (Tambon Pho chai, King Amphoe Kok Pho Chai), site 2 (Tambon Non Sa-at, Amphoe Wang Yai), site 1 (Tambon Tawad, Amphoe Wang Noi), site 11 (Tambon Hau Na Kham, Amphoe Kranuan), and site 4 (Tambon Phulek, Amphoe Banphai), respectively. Then compiling with the information of field investigation, site 4 was evaluated as the preferred site for secured landfill. In addition, GIS model is able to visualize subsurface information of the preferred site and to produce the necessary information for the Visual MODFLOW model’s input files. Under the designated condition, model simulation predicted that the lead contaminant from the preferred site would not reach any well within 7,300 days (20 years) after leaking. The study result showed that the development and application of EGIS was achievable.