Supporting climate change adaptation worldwide: a web application for exploring uncertain future changes in water resources

Abstract. While adaptation to changing water resources due to climate change is necessary everywhere, information about their potential future changes has not been easily accessible to most climate change adaptation processes. The free interactive web application Climate Change Impact of Water Resources (CCIWR) Explorer presents the output of a multi-model ensemble of global hydrological models. It provides state-of-the-art information to support participatory climate change adaptation processes worldwide. What makes the CCIWR Explorer unique is its ability to inform climate change adaptation decisions that account for stakeholder risk aversion. It not only shows the projected median future change in total water resources, groundwater resources, and evapotranspiration in the four seasons or annually, but also which fraction of the ensemble members project a change that stakeholders consider hazardous. Three visualizations are provided: Two map views as well as “Local Insights”, percentile boxes showing the range of future changes in individual 0.5° grid cells. The Explorer was evaluated regarding effectiveness, efficiency, operability, user engagement, and beneficialness. This was achieved through an online user survey, in which 21 pilot users familiarized themselves with the web application by completing two tasks before evaluating various aspects of the Explorer. On average, user satisfaction was high. Satisfaction and the number of correct answers are positively correlated with user expertise. Based on experiences with using multi-model ensemble projections to inform stakeholders in three participatory processes, we recommend that experts, such as water engineers and climate managers, consult the CCIWR Explorer to inform stakeholders. The Explorer is also suited to direct use by university students and researchers.