One of the challenges to managing water resources and understanding their sources is the heterogeneity created by interactions among hydrological, ecological and anthropological processes and how it is best characterized. An option recently applied to other scientific disciplines is identifying and analyzing the emergent phenomena of complex systems or networks, which are far from equilibrium and whose components self-organize into novel structures/processes via their collective interactions with each other and the environment. A new level of organization and complexity emerges that cannot be predicted from or attributed to the components alone. Deriving predictions based on functionally emergent properties (top-down) of watershed systems differs considerably from making predictions based on reductionist models (bottom-up) of those systems.

River networks have been shown to function as hierarchically nested processes from which stability emerges as a property that buffers variation and extreme events. It is the connectivity and interactions (over a range of spatiotemporal scales) among geomorphic and hydrologic components of watersheds or river networks that give rise to the emergent properties. There are a number of statistical and representative sampling techniques available to identify and quantify component connectivity, the importance of which is exemplified by the extent to which connectivity affects the way that rainfall events alter moisture, heat and carbon fluxes associated with drought. In essence, events transmit information through connected components of watersheds, such that accrued information is at the root of a system’s emergent properties. This presentation highlights some of the ways that emergent properties, which have been influential in expanding the perspectives applied to other sciences, are now being applied to water resources and the associated systems.