This project aims at resolving the source of unexpected excess water in major Arctic rivers, something that is both a topic of intense discussion in the community and also of major importance for hydrologists, climate scientists, ocean modelers, and ecologists, and whose implications extend beyond the Arctic region. I am collaborating with leading Arctic water and climate scientists at the University of New Hampshire, USA, in an attempt to resolve this unknown. The main working hypotheses of this project is that mobilization of groundwater or other pools of stored water, for example in the form of permafrost or ground ice, contribute with some portion of the excess discharge in Arctic rivers. The project will attempt to identify and characterize the areas where a potential contribution of stored water to surplus discharge in the Arctic may arise, assess a quantity range of this contribution, through a multi-modeling approach, and evaluate the agreement between different modeling approaches on where the water originates.