Spatial UTA (S-UTA) – A new approach for raster-based GIS multicriteria suitability analysis and its use in implementing natural systems for wastewater treatment

•S-UTA is a new approach for supporting GIS-based suitability analysis.•An ArcGIS add-in that supports S-UTA has been developed.•S-UTA is performed to identify suitable locations for NSWT.•Comparative analysis with other well established methods is conducted.

The identification of sites for locating new natural systems for wastewater treatment (NSWT), such as stabilization ponds and constructed wetlands, should combine multiple crucial factors (environmental, design, social and economic), and thus the implementation of multicriteria decision-making (MCDM) methods is required. In addition, the spatial nature of the site selection process necessitates the use of geographic information systems (GISs) because they are unanimously recognized as the most appropriate tool capable of supporting sophisticated spatial decision making. The resulting multicriteria spatial decision support systems (MC-SDSSs) provide a consistent framework for dealing with conflicting objectives while integrating the decision makers' (DMs') preferences in spatially related patterns/problems. A map-based, interactive UTAII implementation is presented, which provides a link between a well-understood decision support method and exploratory geographic visualization. Spatial UTA (S-UTA) is applied in a real case study concerning the ranking of candidate sites for implementing natural systems for wastewater treatment in the Evros–Rodopi prefectures of northeastern Greece. Finally, the obtained results are compared with those derived using other MCDM approaches to evaluate the performance of S-UTA in GIS-based land use suitability analyses.