AHP and GIS Based Multi Criteria Analysis for Sustainable Sewage Disposal: A Case Study in Badulla Urban Area

Sewage waste is one of the major environmental issues in Sri Lanka. Various studies reveal that about 50% of sewage waste is disposed of unscientifically in to open areas or water bodies. It creates problems to both the public health and the environment. As such, this study identified potential locations for sewage disposal sites using the Analytical Hierarchy Process (AHP) based Multi-Criteria Analysis (MCA) methods with Geographical Information System (GIS), for the Badulla Urban Area (BUA). Environmental aspects, geological and topographical aspects, and socio-economic aspects are identified as key parameters to be considered when doing land suitability analysis for sewage disposal in BUA. The study identified that of the total area, 87.36% of was not suitable, 1.10% less suitable, 9.37% moderately suitable, and 2.17% as suitable. Using the resultant classified suitability map, field verification was carried out to determine the final optimal site. Hence, the application of GIS-based MCA has been demonstrated as an appropriate methodology to solve multiple choices in sewage disposal site selection. This would be very much needed in the concept of city planning across the country.