摘要：Metropolitan cities like Chennai facing rapid urbanisation. This results in informal extension of cities in peri-urban and rural areas. Once the city expands the problem arising is the water supply and sewage treatment system. In the present work an attempt is made in site suitable selection of Decentralised treatment plants (DCTP) with appropriate waste water treatment technologies using GIS techniques. Multicriteria analysis were performed by the combination of Analytical Hierarchy Process (AHP). Six thematic maps were considered such as population density map, landuse map, slope map, soil map, cost map and technology. Different classes were identified for each thematic maps. Using Analytical Hierarchy Principle (AHP) [1] (Saaty, 2000), a paired comparison matrix was prepared for criteria classes and individual class weights and map scores were worked out. These weights were applied in linear summation equation to obtain a unified weight map containing due weights of all input variables. Finally all the weighted maps were reclassified to arrive the best suitable site location of decentralised treatment plants.
