During recent years, our understanding of how climate affects society has advanced greatly. In particular, a vigorous scientific debate on the role of climate in conflict has taken place. Despite advances in finding appropriate ways to study this link, research has so far overlooked a key pathway for societal effects of climate: water on land. Surface waters directly influence human society in many ways that could affect both conflict and cooperation, including resource availability, energy production, and infrastructure risk. This project will combine advanced econometric methods with a water model to separate human modifications of water flows from the remaining background climate signal in water variations. In this way, we will be able to understand how naturalized climate-dependent water flows govern societal responses.