Adaptation of Water Supply to Changing Climate and Land-Use Activities, Case of Ljubljana Water Supply, Slovenia

A risk management methodology is presented for the adaptation of water supply to changing climate and land-use activities, considering socio-economic aspects. Several management options were selected for the case of the public water supply of Ljubljana, the capital of Slovenia. The major management actions for improving drinking water safety are (1) land-use limitations within the drinking water protection areas and (2) drinking water treatment. Trends in groundwater level are decreasing, above all in the area of well fields; therefore, artificial recharge and setting up a new independent well field were also considered. The management actions were evaluated according to several criteria, such as water supply risk reduction for the various users (drinking, agricultural, and industrial) and realization of the actions (cost, flexibility, and leg time). For management options, the ranking "Fuzzy Decimaker" tool was applied, which is based on a Multiple Criterion Decision Making (MCDM) technique. Ranking of management actions has shown that all management actions are good as they are clustering in the corner close to the ideal value. For a particular well field, farming limitations in the drinking water protection areas are the best and water treatment is the worst management action, which is due to high costs, low flexibility, and longer lag time.