Including Climate Change Resilience in Multi-Criteria Decision Analysis of Potential Drinking Water Sources - Method Development for Early-Stage Water Supply Planning

Abstract

Drinking water is a fundamental resource for societal functioning and human health. Sweden has historically had good access to high-quality raw water, but climate change is increasingly posing challenges to both water availability and quality. Therefore, it is essential to consider these factors in the early stages of planning and decision-making regarding new potential drinking water sources. A common approach for selecting new drinking water sources is the application of multi-criteria decision analysis. In this study, the decision support tool WISER was used, which incorporates relevant criteria, scoring, and weighting through a multi-criteria deci sion analysis framework. The aim of the study was to develop a method to integrate climate resilience as a key aspect in multi-criteria decision analysis and apply this within a case study. Two different versions of the method were developed. In the first version, new criteria addressing climate change resilience were added. In the second, this aspect was incorporated into the already existing set of criteria. Both versions were subsequently applied in a case study carried out in Västra Götaland County, Sweden. The case study includes three potential drinking water sources: a groundwater source, an artificial infiltration facility, and a surface water source. The results indicate that both methodological versions are applicable for incorporat ing climate resilience, although they exhibit different strengths and weaknesses. To assess future capacity under different climate scenarios, hydrological modelling was conducted using the SWAT+ software, simulating surface water flows and ground water recharge for the period 2070-2100.