Scenario-Neutral Assessment of Climate Change Sensitivity of Low Flows and Droughts in a Water Resource Management Context

Assessing projected hydrological scenarios from a risk perspective facilitates water governance and management. This study, framed in an informed and contextualized potential impact assessment process, evaluates the physical sensitivity to climate change on low flows and droughts, in a water supply sector, for illustrative purposes. More specifically, we evaluated 28 neutral scenarios using the WaSiM-ETH model on six catchments in Quebec, Canada. Guided by CORDEX—RCP 8.5 projections, the 28 scenarios are constructed around seven annual temperature changes ranging from 0 °C to 6 °C and four non-uniform monthly changes in precipitation ranging from −10% to +20%. The results show, for example, that for a scenario involving a 10% increase in precipitation and a 3 °C rise in temperature, the low flows reductions (7Q2) would range from 15% to more than 30%, the deficit in water volume during the droughts would increase by 2- to 3-fold, and the duration would vary little. No clear correlation was found between low flows and drought behaviour, with each catchment responding individually to the same climatic changes. This study thus advocates a tailored and context-specific methodology to operationalize risk assessment and make water resource management more efficient.