Quantitative vulnerability assessment of water quality to extreme drought in a changing climate

Projected changes in the global climate indicate warmer temperatures and a highly variable hydrologic cycle, portending significant societal effects, particularly those stemming from drought. Whereas the extent of drought-related effects ranges from humans to environmental systems, the impacts on water quality, in particular, require careful investigation. Such investigation should include the interlinkages across climate and stream quality variables and how risk translates for various watersheds, given their particularities with respect to land use, watershed characteristics, and infrastructure. To this end, this study investigated drought assessment and the water quality vulnerability to severe drought, with the goal of informing planning and mitigation as a means to enhance drought resilience. This study was conducted in the Nakdong River basin in South Korea, which is vulnerable to water quality degradation during severe drought. We propose a method to evaluate spatial-temporal droughts based on the water quality risk and to monitor environmental droughts using the probability of exceeding the target water quality to facilitate a resilient proactive response. The results of this study can be used to provide scientific drought monitoring information for assessing real-time water quality monitoring from meteorological drought information. In addition, we expect to categorize vulnerable drought areas and to suggest essential management measures and tailored countermeasures at a local scale.